GB1568817A

GB1568817A – Glass-former comp
– Google Patents

GB1568817A – Glass-former comp
– Google Patents
Glass-former comp

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Info

Publication number
GB1568817A

GB1568817A
GB46919/75A
GB4691975A
GB1568817A
GB 1568817 A
GB1568817 A
GB 1568817A
GB 46919/75 A
GB46919/75 A
GB 46919/75A
GB 4691975 A
GB4691975 A
GB 4691975A
GB 1568817 A
GB1568817 A
GB 1568817A
Authority
GB
United Kingdom
Prior art keywords
fluid medium
glass
drops
process according
beads
Prior art date
1975-11-13
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)

Expired

Application number
GB46919/75A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)

Sovitec SA

Original Assignee
Sovitec SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
1975-11-13
Filing date
1975-11-13
Publication date
1980-06-04

1975-11-13
Application filed by Sovitec SA
filed
Critical
Sovitec SA

1975-11-13
Priority to GB46919/75A
priority
Critical
patent/GB1568817A/en

1976-11-01
Priority to US05/737,344
priority
patent/US4063916A/en

1976-11-03
Priority to ZA766590A
priority
patent/ZA766590B/en

1976-11-04
Priority to DK499476A
priority
patent/DK499476A/en

1976-11-04
Priority to SE7612302A
priority
patent/SE420592B/en

1976-11-04
Priority to NO76763760A
priority
patent/NO141045C/en

1976-11-05
Priority to AU19372/76A
priority
patent/AU504674B2/en

1976-11-05
Priority to IT69644/76A
priority
patent/IT1070068B/en

1976-11-05
Priority to BE1007743A
priority
patent/BE848006A/en

1976-11-05
Priority to CA265,028A
priority
patent/CA1085557A/en

1976-11-05
Priority to FR7633820A
priority
patent/FR2331524A1/en

1976-11-08
Priority to ES453395A
priority
patent/ES453395A1/en

1976-11-09
Priority to AT0831676A
priority
patent/AT373570B/en

1976-11-10
Priority to CH1417076A
priority
patent/CH611583A5/xx

1976-11-10
Priority to LU76167A
priority
patent/LU76167A1/xx

1976-11-10
Priority to NL7612492A
priority
patent/NL7612492A/en

1976-11-10
Priority to JP51135829A
priority
patent/JPS5262324A/en

1976-11-11
Priority to DE19762651545
priority
patent/DE2651545A1/en

1980-06-04
Publication of GB1568817A
publication
Critical
patent/GB1568817A/en

1983-01-20
Priority to JP58007993A
priority
patent/JPS6031779B2/en

Status
Expired
legal-status
Critical
Current

Links

Espacenet

Global Dossier

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239000012530
fluid
Substances

0.000
claims
description
122

239000011324
bead
Substances

0.000
claims
description
108

239000011521
glass
Substances

0.000
claims
description
90

HEMHJVSKTPXQMS-UHFFFAOYSA-M
sodium hydroxide
Inorganic materials

[OH-].[Na+]
HEMHJVSKTPXQMS-UHFFFAOYSA-M
0.000
claims
description
86

238000000034
method
Methods

0.000
claims
description
64

230000015572
biosynthetic process
Effects

0.000
claims
description
36

239000004115
Sodium Silicate
Substances

0.000
claims
description
32

KGBXLFKZBHKPEV-UHFFFAOYSA-N
boric acid
Chemical compound

OB(O)O
KGBXLFKZBHKPEV-UHFFFAOYSA-N
0.000
claims
description
32

239000004327
boric acid
Substances

0.000
claims
description
32

NTHWMYGWWRZVTN-UHFFFAOYSA-N
sodium silicate
Chemical compound

[Na+].[Na+].[O-][Si]([O-])=O
NTHWMYGWWRZVTN-UHFFFAOYSA-N
0.000
claims
description
32

229910052911
sodium silicate
Inorganic materials

0.000
claims
description
32

XLYOFNOQVPJJNP-UHFFFAOYSA-N
water
Substances

O
XLYOFNOQVPJJNP-UHFFFAOYSA-N
0.000
claims
description
32

238000007496
glass forming
Methods

0.000
claims
description
31

XSQUKJJJFZCRTK-UHFFFAOYSA-N
Urea
Chemical compound

NC(N)=O
XSQUKJJJFZCRTK-UHFFFAOYSA-N
0.000
claims
description
29

239000004202
carbamide
Substances

0.000
claims
description
29

VTYYLEPIZMXCLO-UHFFFAOYSA-L
Calcium carbonate
Chemical compound

[Ca+2].[O-]C([O-])=O
VTYYLEPIZMXCLO-UHFFFAOYSA-L
0.000
claims
description
26

239000000463
material
Substances

0.000
claims
description
22

239000000126
substance
Substances

0.000
claims
description
22

238000010304
firing
Methods

0.000
claims
description
21

238000010438
heat treatment
Methods

0.000
claims
description
14

239000007787
solid
Substances

0.000
claims
description
14

229910000019
calcium carbonate
Inorganic materials

0.000
claims
description
13

239000004615
ingredient
Substances

0.000
claims
description
13

KWYUFKZDYYNOTN-UHFFFAOYSA-M
Potassium hydroxide
Chemical compound

[OH-].[K+]
KWYUFKZDYYNOTN-UHFFFAOYSA-M
0.000
claims
description
12

238000006243
chemical reaction
Methods

0.000
claims
description
12

DGAQECJNVWCQMB-PUAWFVPOSA-M
Ilexoside XXIX
Chemical compound

C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+]
DGAQECJNVWCQMB-PUAWFVPOSA-M
0.000
claims
description
11

150000001875
compounds
Chemical class

0.000
claims
description
11

239000003607
modifier
Substances

0.000
claims
description
11

238000001816
cooling
Methods

0.000
claims
description
10

239000007788
liquid
Substances

0.000
claims
description
10

239000000047
product
Substances

0.000
claims
description
8

229910052796
boron
Inorganic materials

0.000
claims
description
7

239000007795
chemical reaction product
Substances

0.000
claims
description
7

239000003795
chemical substances by application
Substances

0.000
claims
description
7

ZOXJGFHDIHLPTG-UHFFFAOYSA-N
Boron
Chemical compound

[B]
ZOXJGFHDIHLPTG-UHFFFAOYSA-N
0.000
claims
description
6

238000001704
evaporation
Methods

0.000
claims
description
6

230000008020
evaporation
Effects

0.000
claims
description
6

BVKZGUZCCUSVTD-UHFFFAOYSA-L
Carbonate
Chemical compound

[O-]C([O-])=O
BVKZGUZCCUSVTD-UHFFFAOYSA-L
0.000
claims
description
5

BPQQTUXANYXVAA-UHFFFAOYSA-N
Orthosilicate
Chemical compound

[O-][Si]([O-])([O-])[O-]
BPQQTUXANYXVAA-UHFFFAOYSA-N
0.000
claims
description
5

230000002378
acidificating effect
Effects

0.000
claims
description
5

229910052910
alkali metal silicate
Inorganic materials

0.000
claims
description
5

229910052751
metal
Inorganic materials

0.000
claims
description
5

239000002184
metal
Substances

0.000
claims
description
5

238000001694
spray drying
Methods

0.000
claims
description
4

239000000470
constituent
Substances

0.000
claims
description
3

230000002401
inhibitory effect
Effects

0.000
claims
description
3

239000002609
medium
Substances

0.000
description
98

239000000243
solution
Substances

0.000
description
64

CDBYLPFSWZWCQE-UHFFFAOYSA-L
Sodium Carbonate
Chemical compound

[Na+].[Na+].[O-]C([O-])=O
CDBYLPFSWZWCQE-UHFFFAOYSA-L
0.000
description
42

239000000203
mixture
Substances

0.000
description
35

VYPSYNLAJGMNEJ-UHFFFAOYSA-N
Silicium dioxide
Chemical compound

O=[Si]=O
VYPSYNLAJGMNEJ-UHFFFAOYSA-N
0.000
description
34

239000007864
aqueous solution
Substances

0.000
description
26

AXCZMVOFGPJBDE-UHFFFAOYSA-L
calcium dihydroxide
Chemical compound

[OH-].[OH-].[Ca+2]
AXCZMVOFGPJBDE-UHFFFAOYSA-L
0.000
description
25

235000011121
sodium hydroxide
Nutrition

0.000
description
25

239000000920
calcium hydroxide
Substances

0.000
description
24

235000011116
calcium hydroxide
Nutrition

0.000
description
24

229910001861
calcium hydroxide
Inorganic materials

0.000
description
24

239000007789
gas
Substances

0.000
description
24

229910000029
sodium carbonate
Inorganic materials

0.000
description
21

239000011734
sodium
Substances

0.000
description
18

239000000377
silicon dioxide
Substances

0.000
description
17

229940083608
sodium hydroxide
Drugs

0.000
description
17

239000005388
borosilicate glass
Substances

0.000
description
16

229910052708
sodium
Inorganic materials

0.000
description
15

238000004519
manufacturing process
Methods

0.000
description
13

238000002156
mixing
Methods

0.000
description
11

238000002360
preparation method
Methods

0.000
description
10

238000012986
modification
Methods

0.000
description
9

230000004048
modification
Effects

0.000
description
9

239000002253
acid
Substances

0.000
description
7

229910021538
borax
Inorganic materials

0.000
description
6

239000004328
sodium tetraborate
Substances

0.000
description
6

235000010339
sodium tetraborate
Nutrition

0.000
description
6

230000001174
ascending effect
Effects

0.000
description
5

230000001413
cellular effect
Effects

0.000
description
5

238000012545
processing
Methods

0.000
description
5

239000007921
spray
Substances

0.000
description
5

239000007858
starting material
Substances

0.000
description
5

239000000725
suspension
Substances

0.000
description
5

239000002585
base
Substances

0.000
description
4

239000006060
molten glass
Substances

0.000
description
4

230000003472
neutralizing effect
Effects

0.000
description
4

VWDWKYIASSYTQR-UHFFFAOYSA-N
sodium nitrate
Chemical compound

[Na+].[O-][N+]([O-])=O
VWDWKYIASSYTQR-UHFFFAOYSA-N
0.000
description
4

238000003756
stirring
Methods

0.000
description
4

238000013019
agitation
Methods

0.000
description
3

238000000354
decomposition reaction
Methods

0.000
description
3

JKWMSGQKBLHBQQ-UHFFFAOYSA-N
diboron trioxide
Chemical compound

O=BOB=O
JKWMSGQKBLHBQQ-UHFFFAOYSA-N
0.000
description
3

-1
e g
Inorganic materials

0.000
description
3

238000005507
spraying
Methods

0.000
description
3

PNEYBMLMFCGWSK-UHFFFAOYSA-N
aluminium oxide
Inorganic materials

[O-2].[O-2].[O-2].[Al+3].[Al+3]
PNEYBMLMFCGWSK-UHFFFAOYSA-N
0.000
description
2

239000005385
borate glass
Substances

0.000
description
2

238000001035
drying
Methods

0.000
description
2

239000000945
filler
Substances

0.000
description
2

239000012634
fragment
Substances

0.000
description
2

239000013067
intermediate product
Substances

0.000
description
2

VTHJTEIRLNZDEV-UHFFFAOYSA-L
magnesium dihydroxide
Chemical compound

[OH-].[OH-].[Mg+2]
VTHJTEIRLNZDEV-UHFFFAOYSA-L
0.000
description
2

239000000347
magnesium hydroxide
Substances

0.000
description
2

229910001862
magnesium hydroxide
Inorganic materials

0.000
description
2

235000012254
magnesium hydroxide
Nutrition

0.000
description
2

230000007935
neutral effect
Effects

0.000
description
2

238000006386
neutralization reaction
Methods

0.000
description
2

239000002245
particle
Substances

0.000
description
2

239000008188
pellet
Substances

0.000
description
2

239000012071
phase
Substances

0.000
description
2

BWHMMNNQKKPAPP-UHFFFAOYSA-L
potassium carbonate
Chemical compound

[K+].[K+].[O-]C([O-])=O
BWHMMNNQKKPAPP-UHFFFAOYSA-L
0.000
description
2

230000001105
regulatory effect
Effects

0.000
description
2

239000004317
sodium nitrate
Substances

0.000
description
2

235000010344
sodium nitrate
Nutrition

0.000
description
2

239000003381
stabilizer
Substances

0.000
description
2

238000003860
storage
Methods

0.000
description
2

WYFCZWSWFGJODV-MIANJLSGSA-N
4-[[(1s)-2-[(e)-3-[3-chloro-2-fluoro-6-(tetrazol-1-yl)phenyl]prop-2-enoyl]-5-(4-methyl-2-oxopiperazin-1-yl)-3,4-dihydro-1h-isoquinoline-1-carbonyl]amino]benzoic acid
Chemical compound

O=C1CN(C)CCN1C1=CC=CC2=C1CCN(C(=O)\C=C\C=1C(=CC=C(Cl)C=1F)N1N=NN=C1)[C@@H]2C(=O)NC1=CC=C(C(O)=O)C=C1
WYFCZWSWFGJODV-MIANJLSGSA-N
0.000
description
1

150000008044
alkali metal hydroxides
Chemical class

0.000
description
1

239000004411
aluminium
Substances

0.000
description
1

229910052782
aluminium
Inorganic materials

0.000
description
1

XAGFODPZIPBFFR-UHFFFAOYSA-N
aluminium
Chemical compound

[Al]
XAGFODPZIPBFFR-UHFFFAOYSA-N
0.000
description
1

239000005354
aluminosilicate glass
Substances

0.000
description
1

ANBBXQWFNXMHLD-UHFFFAOYSA-N
aluminum;sodium;oxygen(2-)
Chemical compound

[O-2].[O-2].[Na+].[Al+3]
ANBBXQWFNXMHLD-UHFFFAOYSA-N
0.000
description
1

239000012736
aqueous medium
Substances

0.000
description
1

239000007900
aqueous suspension
Substances

0.000
description
1

229910052810
boron oxide
Inorganic materials

0.000
description
1

239000011449
brick
Substances

0.000
description
1

230000009172
bursting
Effects

0.000
description
1

125000005587
carbonate group
Chemical group

0.000
description
1

150000004649
carbonic acid derivatives
Chemical class

0.000
description
1

239000000919
ceramic
Substances

0.000
description
1

229910010293
ceramic material
Inorganic materials

0.000
description
1

238000010276
construction
Methods

0.000
description
1

230000003247
decreasing effect
Effects

0.000
description
1

238000007599
discharging
Methods

0.000
description
1

238000011049
filling
Methods

0.000
description
1

239000000499
gel
Substances

0.000
description
1

150000004679
hydroxides
Chemical class

0.000
description
1

238000011065
in-situ storage
Methods

0.000
description
1

229910052738
indium
Inorganic materials

0.000
description
1

238000009413
insulation
Methods

0.000
description
1

DNHVXYDGZKWYNU-UHFFFAOYSA-N
lead;hydrate
Chemical compound

O.[Pb]
DNHVXYDGZKWYNU-UHFFFAOYSA-N
0.000
description
1

239000007791
liquid phase
Substances

0.000
description
1

239000000395
magnesium oxide
Substances

0.000
description
1

CPLXHLVBOLITMK-UHFFFAOYSA-N
magnesium oxide
Inorganic materials

[Mg]=O
CPLXHLVBOLITMK-UHFFFAOYSA-N
0.000
description
1

AXZKOIWUVFPNLO-UHFFFAOYSA-N
magnesium;oxygen(2-)
Chemical compound

[O-2].[Mg+2]
AXZKOIWUVFPNLO-UHFFFAOYSA-N
0.000
description
1

238000012423
maintenance
Methods

0.000
description
1

238000005259
measurement
Methods

0.000
description
1

238000002844
melting
Methods

0.000
description
1

230000008018
melting
Effects

0.000
description
1

239000003973
paint
Substances

0.000
description
1

239000011148
porous material
Substances

0.000
description
1

229910000027
potassium carbonate
Inorganic materials

0.000
description
1

239000002244
precipitate
Substances

0.000
description
1

238000001556
precipitation
Methods

0.000
description
1

239000002243
precursor
Substances

0.000
description
1

230000002035
prolonged effect
Effects

0.000
description
1

230000001737
promoting effect
Effects

0.000
description
1

239000000376
reactant
Substances

0.000
description
1

229920005989
resin
Polymers

0.000
description
1

239000011347
resin
Substances

0.000
description
1

150000003839
salts
Chemical class

0.000
description
1

239000005361
soda-lime glass
Substances

0.000
description
1

229910001388
sodium aluminate
Inorganic materials

0.000
description
1

HUAUNKAZQWMVFY-UHFFFAOYSA-M
sodium;oxocalcium;hydroxide
Chemical compound

[OH-].[Na+].[Ca]=O
HUAUNKAZQWMVFY-UHFFFAOYSA-M
0.000
description
1

239000008259
solid foam
Substances

0.000
description
1

239000011343
solid material
Substances

0.000
description
1

238000007711
solidification
Methods

0.000
description
1

230000008023
solidification
Effects

0.000
description
1

239000002904
solvent
Substances

0.000
description
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238000004017
vitrification
Methods

0.000
description
1

Classifications

C—CHEMISTRY; METALLURGY

C03—GLASS; MINERAL OR SLAG WOOL

C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES

C03B19/00—Other methods of shaping glass

C03B19/10—Forming beads

C03B19/108—Forming porous, sintered or foamed beads

C03B19/1085—Forming porous, sintered or foamed beads by blowing, pressing, centrifuging, rolling or dripping

C—CHEMISTRY; METALLURGY

C03—GLASS; MINERAL OR SLAG WOOL

C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS

C03C11/00—Multi-cellular glass ; Porous or hollow glass or glass particles

C03C11/002—Hollow glass particles

Description

PATENT SPECIFICATION ( 11) 1 568 817
U ( 21) Application No 46919/75 ( 22) Filed 13 Nov 1975 ( 19) N X ( 23) Complete Specification Filed 9 Nov 1976 ( 44) Complete Specification Published 4 Jun 1980
X ( 51) INT CL 3 C 03 B 19/10 LE ( 52) Index at Acceptance f C 1 M 440 441 PB ( 72) Inventors: DANIEL DE VOS ALFRED BERGER ‘D PAUL-MARIE MICHEL ( 54) GLASS-FORMER COMPOSITIONS ( 71) We, SOVITEC S A, a Belgian Body Corporate of Rue Leopold 19-21, Charleroi, Belgium do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particulary described in and by the following statement:
This invention relates to a process of making glass beads by forming a feedstock 5 containing glass-forming material and subjecting small quantities of such feedstock to heat treatment to convert them into glass beads The invention also relates to feedstock compositions suitable for use in such process, and the glass beads formed thereby.
Various processes are known for making glass beads In one known process a supply of molten glass is divided into drops which are projected through a cooling zone in which they 10 solidify This process involves the mechanical handling of a molten glass feedstock, for which expensive apparatus is required It is technically difficult to project a continuous flow of molten glass in the form of small drops The higher the glass temperature the more severe are the demands on the construction and maintenance of the apparatus The lower the molten glass temperature the more difficult is it to form drops of controlled size and to 15 achieve reasonably high production rates The said known process is moreover not capable of producing glass beads which are of cellular form.
It is also known to produce glass beads from pellets or fragments of a solid feedstock which can be prepared at temperatures well below glass melting temperatures In some cases pellets are moulded at elevated temperatures from a mixture incorporating powdered 20 glass In other cases fragments of a solidified composition incorporating glass-formers are prepared by a sequence of steps preparatory to being converted to glass beads The numerous steps involved in the preparation of the feedstock in such prior processes makes them very laborious and such preparation requires quite expensive apparatus.
In addition to being complex and expensive, the processes above described using a 25 pelletized or fragmented solid feedstock suffer from the limitation that they are not capable of producing extremely small glass beads such as are now occasionally in demand for various industrial purposes.
It is an object of the present invention to provide a process whereby, starting from a glass-former composition, glass beads can be more easily prepared A further object of the 30 invention is to provide a process wherein high production rates can be achieved in plant of relatively small scale, using a single furnace Yet a further object is to provide a process which can easily be carried out so as to produce cellular glass beads of very small sizes.
According to the present invention, a process of making glass by forming a feedstock containing glass-forming material, and subjecting small quantities of such feedstock to heat 35 treatment to convert them into glass beads, is characterised in that the feedstock is prepared as a fluid medium comprising an aqueous liquid in which all or most of the glass-forming material is dissolved, and drops of such fluid medium are converted to glass beads by causing the drops to travel in separated condition first through a heating zone at glass-forming temperature to cause evaporation of liquid and formation of glass from the 40 glass-forming material, and then through a cooling zone to cause the glass to solidify.
This process is much more easily performed than the previously known processes hereinbefore described The formation of drops of a fluid feedstock of suitable composition can be achieved at room temperature and does not require elaborate processing steps.
Various useful glass formers can be dissolved in water or other aqueous media to form a 45 1 568 817 solution Conventional mixing apparatus can be used in the formation of the feedstock The formation of the feedstock into drops can be achieved very easily by spraying Very high production rates can be achieved.
Another important advantage of the invention is that cellulated beads can be produced in various predetermined sizes, including sizes below the minimum attainable by the prior 5 processes The production of such beads does not entail complication of the process or apparatus All that is required is control of certain processing conditions, as will hereafter be explained.
For the purposes in view the fluid medium should be of low viscosity Preferably the fluid medium comprises at least 60 % by weight of water Such compositions are highly fluid and 10 by reason of this fact they can very easily be divided into drops, even drops of very small sizes, e g substantially below 1 mm in diameter.
Glass-forming material or so-called «batch» compositions of well known types can be used in carrying out the invention Such compositions usually comprise one or more glass network formers, glass modifiers, and one or more stabilizers The glass forming material 15 may comprise a product (glass-former) which is in itself vitrifiable by firing Alternatively the fluid medium may contain in dissolved state separate glass-formers which react together to form a said vitrifiable reaction product when the temperature of the composition is raised to a certain level It is preferable for the entire glass-former or batch composition, including any glass-modifier and stabilizer which may be present, to be in solution in the liquid It is 20 however within the scope of the invention to prepare and use a feedstock wherein a certain amount of the glass-forming material, e g a proportion of one or more ingredients thereof, is in undissolved state From this explanation it will be understood that the term «fluid medium» as used in defining the process according to the invention includes a medium containing solid particles in suspension in the liquid However it is preferable to employ a 25 medium wherein suspended particles (if any) are of colloidal size Such media remain homogenous without agitation or stirring.
In certain processes according to the invention the fluid medium forming the drops includes one or more glass-formers for forming a borosilicate or silicoborate glass Such glass-forming material may comprise sodium silicate and a boroncontaining compound or a 30 reaction product of such substances Borosilicate and silicoborate glasses are particularly well adapted for forming glass beads for use in manufacturing a range of different industrial products In preparing the fluid medium constituting the feedstock, sodium silicate and a boron-containing compound reactive therewith may be employed in relative proportions selected according to the eventual glass composition required, as in conventional glass 35 manufacture.
The process according to the invention is of course not restricted to the production of beads of borosilicate or silicorborate glasses As a further example, the fluid medium forming the drops may contain a glass-former or glass-formers which is or are converted by the firing step to an alumino-silicate glass The fluid medium may e g contain an aluminium 40 compound as one of two reactant glass-formers Such compound may be in colloidal solution in the liquid phase.
In preferred embodiments of the invention, the fluid medium forming the drops contains one or more dissolved glass-formers which would normally form a gel, but also includes a dissolved ingredient or ingredients which inhibit(s) such gel formation Such fluid media are 45 recommended because generally speaking glass-formers which form a gel in water lead to glasses which have the most satisfactory properties for use in various industrial products By incorporating a substance which inhibits gel formation, considerable advantages are achieved The preparation of the fluid medium can take place in advance of the formation of the drops without it being necessary to resort to substantial heating or agitation to form 50 and maintain the medium in fluid condition.
For achieving the best results, the fluid medium contains a dissolved reaction product or dissolved reaction products of an alkali metal silicate, e g, sodium silicate with an acidic boron-containing compound e g boric acid (H 2 B 03), boric anhydride (B 203) or borax (Na 2 B 4 07 10 H 20), and a p H modifier which inhibits gel formation Such reaction products 55 are precursors of borosilicate and silicoborate glasses By way of example, the fluid medium may be one obtained by addition of sodium silicate to neutralised boric acid solution, the boric acid being used in a proportion by weight of more than 25 % with respect to the weight of the anhydrous silicate.
Preferably one or more alkali metal hydroxides, e g sodium or potassium hydroxide is 60 used as neutralising agent in preparing the fluid medium Such hydroxides have properties which make them particularly suitable The most favoured neutralising agent is sodium hydroxide Such compound can be used as such in the preparation of the feedstock.
Alternatively the sodium hydroxide can be formed in situ in the fluid medium by reaction between other ingredients, e g sodium carbonate and calcium hydroxide 65 1 568 817 In the firing stage of the process the evaporation of the water vapour creates pressure which generally result in the formation within the individual drops, of cells which become «frozen-in» during the cooling stage so that the corresponding glass beads are of cellular form, whether unicellular or multicellular.
Whether or not cellular beads are formed depends on a number of different parameters 5 The influential factors, which will be referred to again later in this specification, include the firing conditions and the composition of the feedstock itself Assuming cellulation to be a desired result in a given case, its attainment can be encouraged at the feedstock preparation stage by including in the feedstock one or more solid or dissolved substances giving rise to the evolution of gas in the firing zone The invention includes processes wherein the fluid 10 medium contains such a substance or combination of substances In some cases the fluid medium contains such a substance which decomposes or burns in the firing zone In other cases the fluid medium contains substances which react under the temperature conditions in the firing zone, with evolution of gas.
In certain processes according to the invention, a metal carbonate is present in the 15 feedstock Metal carbonates are very suitable gas-evolving substances A very satisfactory way in which to form a medium comprising such a metal carbonate and caustic soda as p H regulator is to employ sodium carbonate and slaked lime as ingredients in the preparation of the fluid medium These ingredients react to form sodium hydroxide and calcium carbonate, the latter substance forming a disperse phase in the aqueous liquid During 20 firing to glass-forming temperatures, gas is evolved due to decomposition of the carbonate and the caustic soda and calcium carbonate yield Na 2 O and Ca O which participate in and favourably influence the formation of the glass In this example the suspended calcium carbonate in the feedstock accordingly serves both as a glass-former and as a cellulating 1 agent 25 Another very satisfactory gas evolving substance is urea The invention includes processes in which the fluid medium contains urea This gas-former is available at low price.
The fluid medium constituting the feedstock may incorporate in addition to the ingredients hereinbefore referred to, any other ingredient, compatible therewith and with 7 j the formation of the glass beads, for improving the process or the product 30 In one advantageous way of forming the drops of fluid medium which are converted to glass beads, the fluid medium is fed to one or more sprayers from which the fluid medium issues in drops The subdivision of the fluid medium into drops can be assisted by the action of one or more gas streams.
In some processes according to the invention the fluid medium is actually formed in the 35 form of drops by delivering separate fluid streams containing different constituents of the fluid medium into one or more gas streams in which the materials of the different fluid streams coalesce in the form of drops This latter procedure affords special advantages if thedrops are to be formed of a fluid medium which if it were pre-formed would need to be kept at elevated temperature and/or in agitated or stirred condition to avoid precipitation or gel 40 formation such as would prevent the medium from being formed into drops in the required manner By forming the medium ab initio in the form of drops as above referred to the need for such pre-heating or stirring can be obviated.
The sizes of the drops can be easily controlled for producing beads of required sizes.
Preferably the drops are entirely or substantially entirely of a size not exceeding 2 mm in 45 diameter It is very satisfactory to form drops in the size range 01 to 1 0 mm The formation of such small drops is easily accomplished due to the physical nature of the fluid medium, particularly if it comprises a very dilute solution as hereinbefore recommended.
The drops of fluid medium may be projected into one or more gas streams whereby they are kept in separated condition while the glass-forming material becomes converted to glass 50 and whereby the resulting vitreous drops are carried into a cooling zone where they solidify sufficiently to allow them to come into contact with each other without mutual adherence.
The structure of the beads on solidification is influenced by the temperature/time curve during the heat treatment of the drops and the chemical nature of the glass-forming composition The higher the viscosity of this composition at any given moment, the higher 55 is its resistance to flow under the influence of gas pressure generated by evaporation of the solvent and/or by decomposition of any gas former such as a urea which may be present.
Preferably the temperature in the firing zone corresponds with a glass viscosity of about lk 10,000 centipoises e g from 5000 to 20,OO O c P When forming beads of ordinary soda-lime 6 ( 1 t glass, it is suitable for the temperature in the firing zone to be about 1000 ‘C 60 The invention includes processes wherein the fluid medium and the temperature/time curve relating to the treatment in the firing and cooling zones are such that the drops are wholly or mainly converted to hollow glass beads i e beads in which the glass is substantially confined to an outer shell Such outer shell may be without pores or cells but generally the shell is of microcellular form Such hollow beads have various important 65 1568 817 industrial uses, e g as filler in concrete and ceramic mixes, due to their low bulk density.
The formation of such hollow beads is promoted by rapid heating of the drops and a brief residence time in the firing zone so that droplets of fluid medium are subjected to practically instantaneous surface drying with formation on each droplet of a surface skin.
Under the action of the heat, entrapped gas expands causing expansion of the droplets 5 Rapid vitrification and cooling of the skins prevents their collapse.
While the performance of a process according to the invention generally results in the formation of hollow beads as above referred to, conditions may be such that the resulting beads or a large proportion of them are of porous or solid foam structure throughout their cross-section 10 The sizes of the initial drops of the fluid medium influences the sizes of the final beads.
Generally speaking, the larger the size of an initial drop the more tendency is there for such drop to become disrupted and transformed under the influence of internal gas pressure into a plurality of smaller drops This factor enables glass beads of very small sizes to be produced without forming initial drops of the same or a smaller order of size 15 The invention includes processes as hereinbefore defined wherein the fluid medium, the sizes of the initial drops thereof and the temperature/time curve relating to their treatment in the firing and cooling zones are such that at least some of the drops are disrupted by gas pressure and form droplets of smaller size, and such smaller droplets become converted into glass beads In certain of such processes according to the invention the initial drops are all 20 or mostly smaller than 500 microns and the glass beads formed therefrom are in the size range 10 to 250 microns.
As an alternative, for forming very small beads, the fluid medium may initially form drops of such small sizes that they are substantially instantaneously dried in the firing zone and undergo conversion to glass beads without exploding or otherwise splitting into smaller 25 droplets Drops which are of such small sizes, even down to 10 microns in size, can be formed e g with the aid of ultrasonic vibrations as will hereafter be exemplified The invention includes processes in which the drops are initially all or mostly below 100 microns in size.
The invention includes glass beads formed by a process as hereinbefore defined 30 The invention also includes fluid media for use in such processes, such media comprising stable solutions of glass forming material Thus the present invention includes a fluid medium suitable for use as feedstock in the formation of glass beads, such medium comprising an aqueous liquid containing one or more dissolved products of reaction of an alkali metal silicate with an acidic boron-containing compound, and a p H modifier 35 inhibiting gel formation The boron-containing compound is preferably selected from boric acid, boric anhydride and borax.
Such fluid media are particularly suitable for use in glass bead manufacture as hereinbefore defined The said media can be prepared, stored if need be, and easily sprayed and fired as drops of required sizes depending on the sizes of the glass beads which it is 40 desired to manufacture The fluid media can be devoid of suspended solid ingredients tending to settle on standing for prolonged periods If any suspended solid ingredient is present then the homogeneity of the medium can be preserved or restored during or after storage by simple stirring.
Such fluid media also have other potential uses For example they can be spray-dried at 45 temperatures far below glass-forming temperatures to produce prills of glass-forming material Such prills can be handled and stored as an intermediate product which can be converted into glass beads by introducing the prills into a furnace at glass-forming temperatures To assist in formation of such prills, the fluid medium may contain one or more additional ingredients for promoting coherence of the quanta of glass-forming 50 material in the individual drops on spray-drying thereof However a sufficient binding function will normally be fulfilled by the alkali metal silicate.
In the preparation of such fluid media according to the invention it is necessary, in order to prevent gel formation, to neutralise the acidic boron-containing compound by addition of a base (the p H modifier) before bringing the silicate and boroncontaining compound 55 together.
In preferred fluid media according to the invention the p H modifier is sodium or potassium hydroxide.
Particularly advantageous fluid media according to the present invention are those obtained by addition of sodium silicate to neutralised boric acid solution, the boric acid 60 being used in a proportion of more than 25 % by weight with respect to the weight of the anhydrous silicate.
The invention includes fluid media as hereinbefore defined wherein the medium contains a solid or dissolved substance or a combination of such substances which will give rise to the evolution of gas on introduction of the medium into a heating zone at spray-drying or 65
A Rlass-forming temperature Such media are very useful in the production of cellulated glass beads or in the production of spray-dried prills serving as an intermediate product in the formation of such beads In certain of such media according to the invention the medium contains a said solid or dissolved substance which will decompose with evolution of gas on heating of the medium in a said zone Preferably said gas-evolving substance is a metal 5 carbonate or urea.
A particularly preferred fluid medium according to the invention is one in the preparation of which sodium hydroxide has been employed as a neutralising agent inhibiting gel formation and the medium incorporates suspended calcium carbonate.
Hollow glass beads made by a process according to the invention have various potential 10 uses due to their low bulk density and thermally insulating properties By way of example, such hollow beads can be incorporated as filler in concrete, plasters, resins, paints and ceramic materials The beads can also be used as a loose filling material in cavity walls for thermal insulation purposes, and they can be sintered together to form cellular glass bricks or other structures 15 Examples will now be given of processes and fluid medium according to the invention In the course of these examples, reference will be made to the accompanying diagrammatic drawings in which:
Figure 1 shows a plant for manufacturing glass beads by a process according to the invention; and 20 Figure 2 shows a modified spraying appliance for use in a plant as illustrated in Figure 1.
Example 1
Hollow beads of soda-lime glass were manufactured in a plant as represented in Figure 1.
This plant comprises four vessels 1, 2, 3 and 4 for holding quantities of starting materials 25 The vessels have stirrers driven by motors (not shown) Vessel 1 contained an aqueous solution of commercial sodium silicate ( 380 Baumd) Vessel 2 contained an aqueous solution of calcium hydroxide at 80 WC Vessel 3 contained an aqueous solution of sodium carbonate at 80 WC Vessel 4 contained an aqueous solution of urea at 60 WC.
Calcium hydroxide solution and sodium carbonate solutions from vessels 2 and 3 were fed 30 into a mixing tank 5 in a ratio corresponding with 2 64 parts by weight of calcium hydroxide per 3 41 parts by weight of sodium carbonate The solutions were intimately mixed in tank 5 by means of its stirrer and a reaction occurred between the calcium hydroxide and sodium carbonate, resulting in the formation of a solution containing sodium hydroxide, calcium carbonate and a small residual amount of dissolved sodium carbonate 35 The solution formed in mixing tank 5 and sodium silicate solution from vessel 1 were fed into a principal mixer 6, likewise fitted with a stirring device, in proportions corresponding with 100 parts by weight of sodium silicate per 2 64 parts by weight of calcium hydroxide and per 3 41 parts by weight of sodium carbonate At the same time water was fed into the mixer 6 via supply line 7 to bring the viscosity of the fluid medium in the mixer to 2,300 40 centipoises.
On a first run, a valve 8 between the vessel 4 and the mixer 6 was closed so that urea was not used in the process.
The fluid medium formed in tank 6 contained dissolved sodium silicate and sodium hydroxide, and calcium carbonate in suspension In the formation of glass beads from this 45 fluid medium as will now be described, those three constituents together served as glass-forming material and the calcium carbonate additionally served as a cellulating agent.
The fluid medium was fed from mixer 6 via line 9 into a container 10 fitted with a stirrer, in which container the viscosity of the medium was measured Depending on this measurement the flow of water into the mixer 6 via the water supply line 7 was regulated so 50 as to keep the viscosity of the fluid medium at about 2,300 c P After passing through a filter 11, the fluid medium was delivered by a pump 12 to spray heads 13 in the fluid medium was atomised by means of compressed air delivered via air line 14 from a compressor 15 The spray heads 13 discharged the fluid medium as drops smaller than 500 microns in size The drops were discharged directly upwardly into a furnace 16 fired by gas burners 17 located at 55 the furnace base The gas temperature at the bottom of the furnace was 1100 C.
On contact with the ascending currents of hot gas in the furnace many of the drops of fluid medium became disrupted by internal pressures generated by evaporation of water and decomposition of calcium carbonate and formed drops of still smaller sizes All of the o drops were carried upwardly within the furnace by the hot gas streams During their ascent, 60 and as the temperature of the drops increased towards 750 ‘C, solid material in the individual drops became converted to a vitreous skin or envelope At the same time expansion of gas entrapped in the drops increased their volumes The approximate average residence time of the drops within the furnace was 2 seconds.
The drops, in the form of hollow glass beads, were discharged from the top of the furnace 65 1 568 817 1 568 817 into a conduit 18 leading tangentially into a cyclone separator 19 having a central top opening 20 for the discharge of gases and a bottom apex aperture 21 for the discharge of the beads During their movement along conduit 18 and within the cyclone separator, the beads became cooled sufficiently for them to be collectable in bulk without mutual adherence of the beads The beads were discharged from the cyclone separator into a hopper 22 and from 5 there onto a conveyor 23 for transportation to a delivery point where they could be stored or packaged or put directly to industrial use.
The hollow glass beads were composed of glass of the following approximate composition by weight:
10 Si O 2: 70 % Na 2 O: 25 % Ca O: 5 % 15 The hollow beads were mostly in the size range between 10 and 250 microns and they had a bulk density of 0 1 to 0 3 g/cm 3 The majority of the beads were formed by microcellular shells.
In a second run, the same processing conditions were observed but the valve 8 was opened to cause urea to be introduced into the compositon of the fluid medium formed in 20 mixer 6 in a proportion of approximately 3 % by weight based on the weight of the sodium silicate Hollow glass beads were formed as in the first run but they had a slightly lower bulk density.
Example 2 25
The plant represented in Figure 1 was used for forming hollow glass beads in the following manner.
Vessel 1 contained finely divided silica as marketed under the Trade Mark FARSIL 28 by Sanson S A of France, dissolved in an aqueous solution of sodium hydroxide at 80 ‘C and containing 4 3 kg of sodium hydroxide per 12 9 litres of water Vessel 4 contained an 30 aqueous solution of urea at 60 ‘C, containing 200 g of urea per 10 litres of water.
Vessels 2 and 3 contained respectively an aqueous solution of calcium hydroxide and an aqueous solution of sodium carbonate, both solutions being at 80 ‘C.
The solutions from vessels 2 and 3 were fed into mixing tank 5 in proportions corresponding with 3 707 kg of sodium carbonate per 1 545 kg of calcium hydroxide In the 35 tank 5 a reaction took place with formation of sodium hydroxide and a precipitate of calcium carbonate A small excess amount (about 1 %) of the sodium carbonate remained in solution.
The contents of tank 5, the silica solution from vessel 1, and the urea solution from tank 4 were introduced into the mixer 6 in proportions corresponding with 10 kg of silica per 3 707 40 kg of sodium carbonate, per 1 545 kg of calcium hydroxide, and per 500 g of urea The temperature of the fluid medium in the mixer 6 and during its delivery to the furnace 16 was maintained at 80 ‘C and water was fed into the mixer 6 at a rate which maintained the viscosity of the fluid medium at 2,000 c P Under those conditions the silica, sodiumhydroxide and urea remained in solution whereas the calcium carbonate formed a disperse 45 phase of the medium.
The fluid medium was sprayed into the furnace 16 as in Example 1.
The product collected from the apex of the cyclone separator consisted of glass beads all or most of which were hollow and in the size range 10 to 500 microns The glass shells of most of the beads contained microcells The glass of which the beads were composed had 50 the following approximate composition by weight:
Si O 2 60 % Na 2 O 33 % Ca O 7 % 55 When the foregoing example was modified by replacing a part or the whole of the calcium hydroxide starting material, by hydrated magnesium oxide (Mg(OH)2) and/or hydrated alumina (Al,03 3 H 20) similar results were obtained, but with corresponding modification 60 of the composition of the glass Similar results to those obtained in that example were also achieved when part of the sodium carbonate starting material was replaced by potassium carbonate.
1 568 817 7 Example 3
Plant as represented by Figure 1 was employed for manufacturing hollow glass beads in the following manner.
The vessels 1 and 4 contained respectively a commercial sodium silicate solution of 380 Be and an aqueous suspension of precipitated calcium hydroxide Vessels 2 and 3 were not 5 used The calcium hydroxide suspension contained 100 g of calcium hydroxide per 200 cc of water The calcium hydroxide suspension was mixed in mixer 6 with the sodium silicate solution fed from vessel 1 in proportions corresponding with 100 g of calcium hydroxide in cc of water per kilogram of sodium silicate.
The sodium silicate solution and the calcium hydroxide suspension in vessels 1 and 4, also 10 the mixture in mixer 6 were maintained at a temperature of 90 WC The viscosity of the mixture in mixer 6 was maintained at 100 c P.
The fluid medium formed in mixer 6 was sprayed into the furnace 16 and conversion to glass beads took place as in Example 1 The furnace temperature, at its hottest zone, was 1000 ‘C The drops discharged into the furnace were below 400 microns in size 15 The product collected from the cyclone separator 19 was constituted by glass beads the majority of which were hollow beads below 350 microns in size, formed from droplets formed by bursting of the drops initially sprayed into the furnace The glass forming the beads had the following approximate composition by weight: 20 Si O 2 64 % Na 2 O 21 % Ca O 14 % 25 The beads had a bulk density of about 0 3 g/cm 3.
In a modification of the foregoing process, the calcium hydroxide was replaced by magnesium hydroxide and hydrated alumina Similar results were obtained except for the modification of the glass composition consequent upon the modification of the starting material 30 Example 4
Sodium borosilicate glass beads were produced in the following manner in plant as represented in the accompanying drawing.
The vessel 1 contained an aqueous solution of commercial sodium silicate ( 380 B 6) 35 Vessels 2 and 3 respectively contained an aqueous solution of calcium hydroxide and an aqueous solution of sodium carbonate, both solutions being at 80 WC These solutions were fed into mixing tank 5 in proportions corresponding with 640 g of sodium carbonate per 310 parts by weight of calcium hydroxide In tank 5 a reaction occured resulting in the formation of a solution of sodium hydroxide containing suspended calcium carbonate 40 The contents of tank 5 were fed into principal mixer 6 together with aqueous silicate solution from vessel 1, an aqueous solution of boric acid at 80 WC and containing 830 g of acid per 5 litres of water, from vessel 4, and an aqueous solution of sodium nitrate containing 200 g of the salt per 3 litres of water, which was fed in from a further storage vessel (not shown) The supply streams to mixer 6 correspond with 10 kg of sodium silicate 45 per 640 g of sodium carbonate per 310 g of calcium hydroxide per 830 g of boric acid per 200 g of sodium nitrate.
The viscosity of the fluid medium in mixer 6 was adjusted by addition of water as required to maintain a value of 1,200 c P.
The fluid medium was sprayed into furnace 16 as drops from 50 to 250 microns in size 50 The furnace temperature at its hottest zone was 950 WC On contact of the drops with the hot ascending gas streams in the furnace, all or most of the drops split into a plurality of smaller drops.
Borosilicate glass beads in the size range 10 to 300 microns were collected from the cyclone separator 19 Nearly all of the beads were of hollow structure comprising 55 microcellular shells The bulk density of the beads was 0 1 to 0 2 g/cm 3 The beads were composed of a borosilicate glass of the following approximate composition by weight:
Si O 2 60 % Na 2 O 25 % 60 B 203 10 % Ca O 5 % In another run the foregoing conditions were modified by replacing the boric acid in 65 1 568 817 vessel 4 by borax This involved a corresponding modification of the composition of the borosilicate glass but otherwise the results were similar.
Example 5
Sodium borosilicate glass beads were produced in the following manner using plant as 5 represented in the accompanying drawing.
The vessel 1 contained a hot solution in caustic soda ( 800 C) of fine silica as marketed under the trade mark FARSIL 28 by Sanson S A of France The solution contained 4 3 kg of silica per 12 9 litres of water.
The vessels 2 and 3 respectively contained an aqueous solution of calcium hydroxide and 10 an aqueous solution of sodium carbonate, both solutions being 80 WC Solutions from these vessels were fed into mixing tank 5 in proportions corresponding with 2 84 kg of sodium carbonate per 1 85 kg of calcium hydroxide In tank 5 a reaction occurred resulting in an aqueous solution of sodium hydroxide containing suspended calcium carbonate.
The solution from tank 5 was fed into the principal mixer 6 together with hot silica 15 solution from vessel 1 and an aqueous solution of boric acid at 60 WC contained in vessel 4, the solution containing 6 24 kg of the acid per 30 litres of water The mixing ratio in the mixer 6 corresponded with 4 3 kg of silica per 2 84 kg of sodium carbonate per 1 85 kg of calcium hydroxide per 6 24 kg of boric acid.
The viscosity of the fluid medium in mixer 6 was maintained at 2,500 c P 20 The fluid medium was sprayed into furnace 16, whose maximum temperature was 9000 C.
On contact with the hot ascending gases in the furnace most of the drops of fluid medium exploded, to form smaller drops.
Borosilicate glass beads were collected from the cyclone separator 19 These beads were in the size range 10 to 250 microns Most of them were of hollow structure with 25 microcellular shells, and their bulk density was 0 2 to 0 3 g/cm 3 The borosilicate glass had the following approximate composition by weight:
Si O, 50 % Na 2 O 25 % 30 B 203 18 % Ca O 7 % Example 6 35
Sodium borosilicate glass beads were formed in the following manner in plant represented in Figure 1 of the accompanying drawing.
Vessel 1 contained an aqueous solution of commercial sodium silicate ( 38 Baume).
Vessel 2 contained an aqueous solution of boric acid at 809 C Vessel 3 contained an aqueous solution of sodium hydroxide of 50 % concentration at 80 WC 40 Boric acid solution and sodium hydroxide solution from vessels 2 and 3 were fed into mixing tank 5 in order to form in this tank a neutral solution This neutral solution was supplied to the principal mixer 6 together with sodium silicate solution from vessel 1, an aqueous solution of urea from vessel 4, and water via supply line 7 The urea solution contained 200 g of urea per 10 litres of water and was at a temperature of 60 WC The mixing 45 ratio in mixer 6 corresponded with 10 kg of sodium silicate per 1 1 kg of boric acid per 200 g of urea and the addition of water was regulated to give the fluid medium in mixer 6 a viscosity of 500 c P.
Due to the neutralisation of the acid by the sodium hydroxide the fluid medium in mixer 6 showed no tendency to gel formation 50 The fluid medium was sprayed into furnace 16 as drops below 500 microns in size The temperature at the bottom of the furnace was 1000 C Under the action of the ascending hot gas streams most of the drops entering the furnace exploded, forming drops of smaller sizes.
Hollow glass beads comprising microcellular shells were collected from the cyclone separator 19 The beads were below 250 microns in size and had a bulk density from 0 1 to 55 0.2 glcm 3 The approximate composition by weight of the borosilicate glass forming the beads was:
Si O o 65 5 % Na O 19 5 % 60 B 203 15 % Hollow beads of a range of different borosilicate glasses can be formed by increasing or decreasing the proportion of boric acid used in the composition of the fluid medium in the 65 A 7 1 568 817 foregoing example and provided the proportion of sodium hydroxide used is correspondingly varied to ensure neutralisation of the medium, gel formation will be avoided By way of example the boron oxide content of the formed glass could be increased to above 50 % by increasing the proportion of boric acid in the fluid medium and in that case the glass has a lower softening temperature so that lower furnace temperatures could be used 5 A further possible modification of the foregoing example resides in the use of calcium hydroxide as base instead of the sodium hydroxide Another possible modification involves the addition of sodium aluminate, e g, in a proportion of 100 g per 10 kg of sodium silicate, so as to improve the chemical resistance of the hollow glass beads produced in the process 10 1 Example 7
Borosilicate glass beads were produced in plant as shown in Figure 1.
The vessel 1 contained a solution formed by dissolving finely divided silica as marketed under the Trade Mark FARSIL 28 in a solution of caustic soda at 90 WC The solution contained 1 kg of silica per 430 g of caustic soda and 1 3 kg of water 15 The vessel 4 contained a solution of borax in water in a concentration corresponding with 800 g of borax per 3 litres of water.
The two solutions were mixed in mixer 6 in proportions corresponding with 800 g of borax per killogram of silica The mixture formed a gel This gel was converted to a solution by heating the contents of the mixer 6 to 90 WC and agitating the mixture for 1 to 4 hours by 20 means of a rotary agitator rotating at about 2000 revolutions per minute.
The solution formed in that way had a viscosity of about 50 c P The solution was sprayed into the furnace 16 and conversion to glass beads took place as in Example 1 The drops discharged into the furnace were less than 100 microns in size.
The borosilicate glass beads collected from cyclone 19 were hollow The glass 25 composition in percentages by weight was approximately as follows:
Si O 2 61 5 % Na 2 O 20 3 % BO 3 18 2 % 30 The beads were less than 150 microns in size and had a bulk density of about 0 4 g/cm 3.
Example 8 35
Sodium borosilicate beads were formed using plant as described with reference to Figure 1 of the accompanying drawings.
Vessel 1 contained finely divided silica as marketed under the Trade Mark FARSIL 28, dissolved in a hot aqueous solution of sodium carbonate The silica and sodium carbonate were present in proportions corresponding with 10 kg of silica per 7 35 kg of sodium 40 carbonate per 24 litres of water The solution was at 80 WC.
Vessel 2 held in aqueous solution of boric acid at 60 WC, containing 5 19 kg of the acid per litres of water.
Vessels 3 and 5 were not used The contents of vessels 1 and 2 were fed into principal mixer 6 in proportions corresponding with 10 kg of silica per 5 19 kg of boric acid, and water 45 was added via supply line 7 to bring the viscosity of the fluid medium in the mixer to 1,000 c P.
In order to avoid gel formation, the contents of the mixer were maintained at a temperature of 90 WC and vigorously stirred for a period of 1 hour.
The fluid medium at the said temperature was sprayed into furnace 16 in which the 50 bottom temperature was 1,1000 C Most of the drops of fluid medium were disrupted on entering the furnace to form a larger number of drops of smaller sizes.
Sodium borosilicate glass beads of hollow form were collected from the cyclone separator 19 The beads were in the size range 10 to 250 microns and had a bulk density of 0 25 g/cm 3.
The glass forming the beads had the following approximate composition by weight: 55 Si O 2 58 % Na 2 O 25 % B 203 17 % 60 In a second run, the foregoing example was modified by feeding a hot aqueous solution of urea at 60 WC into the mixer 6 in a proportion corresponding with 500 g of urea per 10 kg of silica In this case the formed hollow glass beads were found to have a bulk density of 0 17 g/cm 3 65 a 1 568 817 In a further modification of the said foregoing example, an aqueous solution of sodium silicate of 40 % concentration of 380 Baum 6 was used as starting material in vessel 1, instead of the solution of silica in caustic soda The sodium silicate solution was kept at 80 ‘C This sodium silicate solution was mixed in mixer 6 with boric acid solution from vessel 2, and with aqueous urea solution at 60 ‘C from vessel 4, in proportions corresponding with 1 kg of 5 sodium silicate per 0 620 kg of boric acid and per 20 g of urea, and water was added to bring the viscosity of the fluid medium in mixer 6 to 3,000 c P In order to avoid gelification of the medium the contents of the mixer were heated to 900 C and agitated over a period of 8 hours This fluid medium was then sprayed into the furnace under the same conditions as those in the said foregoing example Hollow sodium silico-borate glass beads of a similar 10 size range and bulk density were obtained, the beads being formed of glass having the following approximate composition by weight:
B 203 50 % Si O 2 38 6 % 15 Na 2 O 11 4 % Example 9
Silico-borate glass beads were manufactured in apparatus similar to that shown in Figure 20 1 but with the following modification.
The spray heads 13 at the bottom of the furnace were replaced by atomisers of the form represented in Figure 2 which shows one spray head in cross-sectional elevation The atomiser comprises a body 30 defining a central passageway 31 and a plurality of secondary passageways 32 (of which two appear in the drawing) angularly spaced around the axis of 25 passageway 31 In use fluid media are forced into the body 30 so as to flow along passageways 31, 32 from left to right in the aspect of the drawing The exit end portions 33 of the secondary passageways 32 converge so as to terminate in the immediate vicinity of the exit end of the central passageway 31 An annular chamber 34 is common to the aforesaid secondary passageways 32 and a radial feed channel 35 leads into this annular 30 chamber from the periphery of the body 30 Downstream from the exit ends of the passageways 31, 32 there is a hub or cap portion 36 which is connected to the body 30 by strips 37 which are angularly spaced around the longitudinal axis of the sprayer.
When the central passageway 31 on the one hand and the secondary passageways 32 on the other hand are fed under pressure with streams of different fluid media the streams 35 collide adjacent the exit ends of the passageways while at the same time a part of the formed fluid mixture strikes the hub or cap 35 and the impact creates an ultrasonic vibrationary field which causes division of the fluid mixture into very small droplets, for example one or several dozens of microns in size Atomisers or so-called pulverisators of this type are commercially available For example suitable pulverisators are marketed under the Trade 40 Mark «Sonicore» by Ultrasonic Corporation of the United States of America.
In the process the subject of this Example vessel 1 contained a 40 % aqueous solution of sodium silicate at 380 BB, maintained at a temperature of 90 ‘C The vessel 2 contained a solution of boric acid containing 5 19 kg of acid per 40 litres of water and maintained at a temperature of 60 ‘C Vessel 3 contained a urea solution of 60 ‘C 45 The boric acid solution from vessel 2 was mixed with the urea solution from vessel 3 in tank 5.
The central passageway 31 of each atomiser was connected to vessel 1 via a pump, whilst the annular chamber 34 of each atomiser, feeding the secondary passageways 32, was connected to vessel 5, also via a pump The mixing ratio between the boric acid and the urea 50 in tank 5 and the rates of supply of the solutions from vessel 1 and tank 5 to the atomisers were such as to achieve in each atomiser a mixing ratio corresponding with 0 62 kg of boric acid per 20 g of urea per killogram of sodium silicate.
The droplets discharging from the atomisers were about 50 microns in size Although the drops combined boric acid and sodium silicate, gel formation did not occur The drops were 55 transformed very rapidly under the heat of the furnace into hollow glass beads The beads were less than 70 microns in size The glass had the following approximate composition in percentages by weight:
B 103 50 % 60 Si O 2 386 % Na 2 O 114 % Certain examples of stable fluid media according to the present invention have already 65 11 1 568 817 11 been incorporated in Examples 4 to 6 Those media are very suitable not only for use in processes according to the invention wherein the medium is directly formed into hollow glass beads, but also in other processes, e g, in processes wherein drops of the fluid medium are treated at temperatures sufficient to dry them and convert them to solid prills but insufficient to convert them into glass beads The following are further examples of the 5 preparation of fluid media according to the invention which can be used in either of such ways.
Example 10
1 g 6 5 kg of Na OH flakes were dissolved in 6 5 kg of water at 50 ‘C 11 6 kg of boric acid 10 were then added to this solution The boric acid was neutralised by the Na OH by an exothermic reaction 2 kg of urea was then dissolved in the resulting hot solution This solution, containing the neutralised acid and the urea, was mixed with 100 kg of sodium silicate of 380 Baum 6.
The liquid medium resulting from the foregoing steps is useful as a feedstock for the 15 preparation of solid prills or borosilicate glass-forming material The fluid medium shows no tendency to gel formation so that special measures such as prolonged agitation and heating to high temperatures is not necessary for maintaining the fluid medium in a fluid condition in which it can be easily divided into drops By way of example solid prills of Z borosilicate glass-forming material can be produced by spray-drying the fluid medium It 20 suffices to spray the medium into a drying shaft in which the drops are dried by ascending currents of hot gases at temperatures causing rapid evaporation of the water, e g.
temperatures in the range 3000 to 550 ‘C The resulting prills can be collected and packaged or stored, or transported to a following processing stage The prills can be converted to hollow beads or borosilicate glass by firing them at glass-forming temperatures 25 The quantity of boric acid used per 100 kg of sodium silicate can be varied provided that the quantity of caustic soda used in each case is appropriate for neutralising the solution before addition of the sodium silicate.
J 6 The caustic soda could be entirely or in part replaced by another base.
Example 11
1.75 kg of Na OH flakes were dissolved in 1 75 kg of water at 50 ‘C 2 7 kg of boric acid were then added to this solution The boric acid was neutralised by the Na OH 2 kg of urea was then dissolved in the resulting hot solution This solution, containing the neutralised acid and the urea, was mixed with 100 kg of sodium silicate of 38 Baum 6 35 The fluid medium according to the invention, produced by the foregoing step, is less costly then the medium prepared according to Example 11 Like that medium, it does not form a gel and it can therefore also be easily prepared and sprayed The medium can be spray-dried to form prills of borosilicate glass-forming material for conversion to borosilicate glass in a subsequent processing stage, or can be converted to borosilicate glass 40 beads by spraying the fluid medium directly into a heating zone at glassforming temperature.

Claims (1)

WHAT WE CLAIM IS:-
1 A process of making glass beads by forming a feedstock containing glassforming material, and subjecting small quantities of such feedstock to heat treatment to convert 45 them into glass beads, characterised in that the feedstock is prepared as a fluid medium comprising an aqueous liquid in which all or most of the glass-forming material is dissolved, and drops of such fluid medium are converted to glass beads by causing the drops to travel in separated condition first through a firing zone at glass-forming temperature to cause evaporation of liquid and formation of glass from the glass-forming material, and then 50 through a cooling zone to cause the glass to solidify.
2 A process according to claim 1, characterised in that said fluid medium contains at # least 60 % by weight of water.
3 A process according to claim 1 or 2, characterised in that the fluid medium forming the drops includes one or more glass-formers for forming a borosilicate or silicoborate glass 55 4 A process according to any preceding claim, characterised in that the fluid medium forming the drops contains one or more dissolved glass-formers which would normally form a gel but contains a dissolved ingredient or ingredients which inhibit(s) such gel formation.
A process according to claim 3, characterised in that said fluid medium contains products of reaction of an alkali metal silicate with an acidic boroncontaining compound, 60 and a p H modifier which inhibits gel formation.
6 A process according to claim 5, characterised in that the fluid medium incorporates sodium or potassium hydroxide as said p H modifier.
7 A process according to any preceding claim, characterised in that the fluid medium contains a solid or dissolved substance or a combination of such substances giving rise to the 65 12 1 568 817 12 evolution of gas in the firing zone.
8 A process according to claim 7, characterised in that the fluid medium contains a substance which decomposes in the firing zone with evolution of gas.
9 A process according to claim 8, characterised in that the fluid medium contains a metal carbonate 5 A process according to claim 8, characterised in that the fluid medium contains urea.
11 A process according to any preceding claim, characterised in that the fluid medium is fed to one or more sprayers from which the fluid medium issues as said drops.
12 A process according to any of claims 1 to 10, characterised in that the fluid medium 10 and the drops are formed simultaneously by delivering separate fluid streams containing different constituents of the fluid medium into one or more gas streams in which the materials of the different fluid streams coalesce in the form of drops.
13 A process according to any preceding claim, characterised in that the drops are entirely or substantially entirely of a size not exceeding 2 mm in diameter and preferably in 15 the size range 01 to 1 0 mm.
14 A process according to any preceding claim, characterised in that the temperature in the firing zone corresponds with a glass viscosity of 5000 to 20,000 c P.
A process according to any preceding claim, characterised in that the fluid medium and the temperature/time curve relating to the treatment in the firing and cooling zones are 20 such that the drops are wholly or mainly converted to hollow glass beads.
16 A process according to any preceding claim, characterised in that the fluid medium, the sizes of the initial drops thereof, and the temperature/time curve relating to their treatment in the firing and cooling zones are such that at least some of the drops are disrupted by gas pressure and form droplets of smaller size, and such smaller droplets 25 become converted into glass beads.
17 A process according to claim 16, characterised in that the initial drops are all or mostly smaller than 500 microns and the glass beads formed therefrom are in the size range to 250 microns.
18 A process according to any of claims 1 to 15, characterised in that the initial drops 30 are all or mostly below 100 microns in size.
19 A process of making glass beads substantially according to any of the Examples herein.
Glass beads formed by a process according to any preceding claim.
21 A fluid medium suitable for use as feedstock in the formation of glass beads, 35 characterised in that the medium comprises an aqueous liquid containing a dissolved reaction product or dissolved reaction products of an alkali metal silicate with an acidic boron-containing compound, and a p H modifier inhibiting gel formation.
22 A fluid medium according to claim 21, characterised in that said p H modifier is sodium or potassium hydroxide 40 23 A fluid medium according to claim 21 or 22, characterised in that the medium is one resulting from the addition of sodium silicate to neutralised boric acid solution, the boric acid being used in a proportion of more than 25 % by weight with respect to the weight of the anhydrous silicate.
24 A fluid medium according to any of claims 21 to 23, characterised in that the 45 medium contains a solid or dissolved substance or a combination of such substances which will give rise to the evolution of gas on introduction of the medium into a heating zone at spray-drying or glass-forming temperature.
A fluid medium according to claim 24, characterised in that the medium contains a solid or dissolved substance which will decompose with evolution of gas on introduction of 50 the medium in a said heating zone.
26 A fluid medium according to any of claims 21 to 25, characterised in that sodium hydroxide has been employed as said p H modifier and the medium incorporates suspended calcium carbonate.
27 A fluid medium according to claim 21 and substantially as used in any of the 55 Examples 4 to 6, 10 and 11 herein.
HYDE, HEIDE & O’DONNELL, Chartered Patent Agents, 47 Victoria Street, 60 London SW 1 H OES.
Agents for the Applicant.
Printed for Her Majesty’s Stationery Office, by Croydon: Printing Company Limited, Croydon, Surrey, 1980.
Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A LAY,from which copies may be obtained.
1 568 817

GB46919/75A
1975-11-13
1975-11-13
Glass-former comp

Expired

GB1568817A
(en)

Priority Applications (19)

Application Number
Priority Date
Filing Date
Title

GB46919/75A

GB1568817A
(en)

1975-11-13
1975-11-13
Glass-former comp

US05/737,344

US4063916A
(en)

1975-11-13
1976-11-01
Process of making glass beads from liquid medium feedstock

ZA766590A

ZA766590B
(en)

1975-11-13
1976-11-03
Process of making glass beads and fluid medium for use as feedstock in the formation of glass beads

DK499476A

DK499476A
(en)

1975-11-13
1976-11-04

PROCEDURE FOR THE MANUFACTURE OF GLASS PEARLS AND LIQUID MEDIUM FOR USE AS A FEEDING TUBE IN THE FORMATION OF PLASPERLER

SE7612302A

SE420592B
(en)

1975-11-13
1976-11-04

SET FOR MANUFACTURING GLASS Beads AND LIQUID MEDIUM

NO76763760A

NO141045C
(en)

1975-11-13
1976-11-04

PROCEDURE FOR MANUFACTURE OF HOLE OR POROIC GLASS BULBS

CA265,028A

CA1085557A
(en)

1975-11-13
1976-11-05
Process for making glass beads

IT69644/76A

IT1070068B
(en)

1975-11-13
1976-11-05

PROCEDURE FOR THE MANUFACTURE OF GLASS BEADS AND FLUID COMPOSITION USED FOR THE MANUFACTURE OF GLASS BEADS

BE1007743A

BE848006A
(en)

1975-11-13
1976-11-05

PROCESS FOR MANUFACTURING GLASS BEADS AND FLUID COMPOSITION USED FOR THE MANUFACTURING OF GLASS BEADS,

AU19372/76A

AU504674B2
(en)

1975-11-13
1976-11-05
Making glass beads

FR7633820A

FR2331524A1
(en)

1975-11-13
1976-11-05

PROCESS FOR MANUFACTURING GLASS BEADS AND FLUID COMPOSITION USED FOR THE MANUFACTURING OF GLASS BEADS

ES453395A

ES453395A1
(en)

1975-11-13
1976-11-08
Process of making glass beads from liquid medium feedstock

AT0831676A

AT373570B
(en)

1975-11-13
1976-11-09

METHOD FOR PRODUCING GLASS BEADS WITH CELL STRUCTURE AND FLOWABLE OR LIQUID MEDIUM FOR PRODUCING SUCH GLASS BEADS

CH1417076A

CH611583A5
(en)

1975-11-13
1976-11-10

LU76167A

LU76167A1
(en)

1975-11-13
1976-11-10

NL7612492A

NL7612492A
(en)

1975-11-13
1976-11-10

METHOD OF MAKING GLASS BEADS.

JP51135829A

JPS5262324A
(en)

1975-11-13
1976-11-10
Glass bead production method and raw fluid for production of glass bead

DE19762651545

DE2651545A1
(en)

1975-11-13
1976-11-11

PROCESS FOR THE MANUFACTURING OF GLASS BEADS AND THE PRODUCTS OBTAINED THEREOF

JP58007993A

JPS6031779B2
(en)

1975-11-13
1983-01-20

Expandable bead manufacturing material

Applications Claiming Priority (1)

Application Number
Priority Date
Filing Date
Title

GB46919/75A

GB1568817A
(en)

1975-11-13
1975-11-13
Glass-former comp

Publications (1)

Publication Number
Publication Date

GB1568817A
true

GB1568817A
(en)

1980-06-04

Family
ID=10443066
Family Applications (1)

Application Number
Title
Priority Date
Filing Date

GB46919/75A
Expired

GB1568817A
(en)

1975-11-13
1975-11-13
Glass-former comp

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US
(1)

US4063916A
(en)

JP
(2)

JPS5262324A
(en)

AT
(1)

AT373570B
(en)

AU
(1)

AU504674B2
(en)

BE
(1)

BE848006A
(en)

CA
(1)

CA1085557A
(en)

CH
(1)

CH611583A5
(en)

DE
(1)

DE2651545A1
(en)

DK
(1)

DK499476A
(en)

ES
(1)

ES453395A1
(en)

FR
(1)

FR2331524A1
(en)

GB
(1)

GB1568817A
(en)

IT
(1)

IT1070068B
(en)

LU
(1)

LU76167A1
(en)

NL
(1)

NL7612492A
(en)

NO
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NO141045C
(en)

SE
(1)

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(en)

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Glaverbel, Brüssel/Bruxelles

GAS-FILLED HOLLOW GLASS BODIES, METHOD FOR THE PRODUCTION AND USE THEREOF

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1985-06-21
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Amorphous and isotropic metal silicate(s) – in which metal is lead, zinc, and/or alkaline earth metal; for mfg. glass

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Glass-ceramic green sheet, multilayer substrate, and manufacturing method thereof

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W. R. Grace & Co.-Conn.
Method of making small hollow glass spheres

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1975-11-13
GB
GB46919/75A
patent/GB1568817A/en
not_active
Expired

1976

1976-11-01
US
US05/737,344
patent/US4063916A/en
not_active
Expired – Lifetime

1976-11-03
ZA
ZA766590A
patent/ZA766590B/en
unknown

1976-11-04
DK
DK499476A
patent/DK499476A/en
not_active
Application Discontinuation

1976-11-04
NO
NO76763760A
patent/NO141045C/en
unknown

1976-11-04
SE
SE7612302A
patent/SE420592B/en
unknown

1976-11-05
IT
IT69644/76A
patent/IT1070068B/en
active

1976-11-05
AU
AU19372/76A
patent/AU504674B2/en
not_active
Expired

1976-11-05
CA
CA265,028A
patent/CA1085557A/en
not_active
Expired

1976-11-05
BE
BE1007743A
patent/BE848006A/en
not_active
IP Right Cessation

1976-11-05
FR
FR7633820A
patent/FR2331524A1/en
active
Granted

1976-11-08
ES
ES453395A
patent/ES453395A1/en
not_active
Expired

1976-11-09
AT
AT0831676A
patent/AT373570B/en
not_active
IP Right Cessation

1976-11-10
JP
JP51135829A
patent/JPS5262324A/en
active
Pending

1976-11-10
NL
NL7612492A
patent/NL7612492A/en
not_active
Application Discontinuation

1976-11-10
LU
LU76167A
patent/LU76167A1/xx
unknown

1976-11-10
CH
CH1417076A
patent/CH611583A5/xx
not_active
IP Right Cessation

1976-11-11
DE
DE19762651545
patent/DE2651545A1/en
not_active
Withdrawn

1983

1983-01-20
JP
JP58007993A
patent/JPS6031779B2/en
not_active
Expired

Cited By (2)

* Cited by examiner, † Cited by third party

Publication number
Priority date
Publication date
Assignee
Title

DE3417585A1
(en)

*

1983-05-13
1984-11-15
Glaverbel, Brüssel/Bruxelles

GAS-FILLED HOLLOW GLASS BODIES, METHOD FOR THE PRODUCTION AND USE THEREOF

GB2177083A
(en)

*

1985-06-21
1987-01-14
Glaverbel
Manufacturing vitreous beads

Also Published As

Publication number
Publication date

SE7612302L
(en)

1977-05-14

NO141045C
(en)

1980-01-09

LU76167A1
(en)

1977-05-18

FR2331524B1
(en)

1982-06-11

AU1937276A
(en)

1978-05-11

JPS58130135A
(en)

1983-08-03

ZA766590B
(en)

1977-12-28

ES453395A1
(en)

1977-11-01

FR2331524A1
(en)

1977-06-10

AT373570B
(en)

1984-02-10

BE848006A
(en)

1977-05-05

JPS5262324A
(en)

1977-05-23

AU504674B2
(en)

1979-10-25

CA1085557A
(en)

1980-09-16

NL7612492A
(en)

1977-05-17

NO141045B
(en)

1979-09-24

SE420592B
(en)

1981-10-19

ATA831676A
(en)

1983-06-15

NO763760L
(en)

1977-05-16

US4063916A
(en)

1977-12-20

JPS6031779B2
(en)

1985-07-24

DE2651545A1
(en)

1977-05-26

DK499476A
(en)

1977-05-14

IT1070068B
(en)

1985-03-25

CH611583A5
(en)

1979-06-15

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Legal Events

Date
Code
Title
Description

1980-08-20
PS
Patent sealed [section 19, patents act 1949]

1986-07-09
PCNP
Patent ceased through non-payment of renewal fee

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