DE2213675A1 - Vitrifiable mixture and method and equipment for its manufacture - Google Patents

Description

Dr. F. Zumsteln sen. - Dr. E. Attmann Dr. R. Koenigsberger - Phya. R. Holzbauer

Dr. F. Zumstoin jun.

Patenlanwalle

8 Munich 2, Bräuhausstraße 4 / III

BOUSSOIS SOUCHOIT NEUVESEL Cas BD

Vitrifiable mixture, and method and plant for its Manufacturing.

The invention relates to a vitrifiable mixture, for the production of glasses of various types, such as urodium lime glasses, Barasilicate glasses and aluminum oxide and silicates containing glasses. The invention also relates to the method for producing this mixture and the installation for exercising it this process for the preparation of this mixture.

There have been numerous investigations so far

employed to improve the melting of the vitrifiable mixtures used to make the glass. These investigations concerned in particular the composition of the vitrifiable Mixture, which in particular can contain various auxiliaries, such as blast furnace slag and alkaline lyes, in which aluminum oxide can also be dissolved, as well as the physical state of the vitrifiable mixture, which is in particular the shape of pellets, lozenges or granules may have.

It is known that physical access

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stand of vitrifiable mixtures in the form of caked Elements such as pellets or granules · a significant increase allows the melting rate of the vitrifiable mixture. ■ - ·

Various methods are also known for briquetting or granulating a vitrifiable mixture to be used, such as extrusion with subsequent parting, pressing or compaction. However, these methods are practical not suitable if they are applied directly to a vitrifiable mixture with the usual grain size, as this is a there is excessive wear and tear on the manufacturing material.

In addition, the duration of the preparation

not negligible, and in the case of high-capacity production, too much and expensive preparatory material is required.

It has also been suggested that this

To remedy the disadvantage that a rotary drum or a granulating plate are used as the granulating apparatus. The experience shows, however, that these are practically not vitrifiable with any common Mixtures can be used, the grain size of which is not very fine and spreads over a wide range (from about 0.1 to 2 mm). This results in a poor yield of the granulating plate, which leads to reintroduction of the Requires products in the manufacturing process, complicates the plant and increases the cost price in an inadmissible manner elevated. The use of the granulating plate for industrial production is therefore excluded, if not ensured it can be seen that the efficiency thereof is practically $ 100.

To remedy these restrictions is

has been provided, the lasable mixture before its formation to grind to independent elements.

This grinding can be done in two ways:

a) By grinding each raw material separately. According to a previously proposed method, the Constituents and especially the most difficult to melt substances, such as silica, ground to such a fineness,

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that more than $ 50 of the same have a dimension less than 20 microns to have. This condition requires very expensive treatments and numerous measures (numerous frequent grain size analyzes, Need for a high degree of purity, lack of iron, which is introduced by the balls of the mill risk of evaporation, difficulties in transport and mixing). Experience has also shown that when the particles have the above fineness, the melting rate paradoxically, it decreases, probably as a result of superficial sintering of the mixture in the bath containing the Prevents gases from escaping. For all of these reasons, such a method has not found practical application.

b) By grinding all of the vitrifiable mixture. On this simultaneous grinding of the components of the Mixture, for example by means of a ball mill, follows according to a known technique granulation with the rotary drum It has also been proposed, as indicated above, to use the granulating plate to form the granules. The use of this Apparatus is common in the cement industry, but this is not the case in the glass industry, as experience has shown has that it was difficult to get a very high yield with this apparatus. So it would be with a vitrifiable mixture, at which more than 50 $ of the ingredients are submicron in size, the yield of granulation with the granulating plate less than $ 50, what a reintroduction of the products in the manufacturing process and would limit the hourly yield in manufacturing

The invention aims to remedy these disadvantages and limitations.

For this purpose, according to the invention, the vitrifiable mixture, which is produced by a ground mixture of products, such as sand, limestone, dolomite, carbonates and others vitrifiable Products is formed, characterized in that an elementary sample of the mixture following fineness conditions enough .:

their specific surface is between 1500 and 7500 cm / g, and preferably between 2800 and 6000 cm / g;

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the particle size distribution of its constituents is such that the residue on a sieve with a mesh of 150 microns is between 0 and 35 $ _f and preferably between 0.5 and 12 $.

Experience has shown that these conditions, with their simultaneous eriüHang a remarkable Allow an increase in the melting rate of the mixture. The reference to a sieve with a mesh of 150 microns comes about because such a sieve is generally used to identify the grain size of a mixture will.

The mixture is brought into granule form preferably by incorporating a binder, which at least formed in part by the oxides entering the composition of the glass, the desired mechanical Gives strength and prevents the formation of dust. This binder can in a manner known per se by sodium silicate or formed by an alkaline sodium or potassium hydroxide solution.

Within the preferred range (2800

to 6000 cm / g and screen residue at 150 microns between 0.5 and $ 12) experience has shown the unexpected result that even under normal industrial conditions (i.e. without strict monitoring of the working conditions) the yield of the granulation with the apparatus mentioned in came close to $ 100. The unexpected relationship between the fineness conditions of the vitrifiable mixture to increase the melting speed and the practically unit yield of the granulation with the granulating plate under industrial conditions is one of the discoveries on which the present invention is based.

Experience has also shown that it is

granulation was possible even outside the preferred range defined above, in the laboratory and in a small amount to make with the granulating plate with an acceptable yield, provided that the granulation is particularly carefully monitored.

According to a preferred embodiment of the

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Invention is sufficient for the production of a soda lime glass with a binder formed by sodium silicate or slaked lime, the composition after grinding and the following characteristics before granulation: ■

Limit values Preferred values

- specific surface area 1500-7500 cm ² / g 35ΟΟ-6ΟΟΟ cm ² / g ■ grain size distribution:

- Sieve residue at 315 microns $ 0-3 $ 0-1

- Sieve residue at 150 microns $ 0-35 $ 0.5-5

- Sieve residue at 100 microns 3 - 60 $ 10 - 25 $

- Sieve residue at 60 microns 15-65 $ 20-50 $

In the above-mentioned pail of a soda lime glass, an alkaline sodium or potassium hydroxide solution can be used as a binder can be used, which is a maximum of 25 to 50 $ the Replaced all of the alkaline bodies, the mixture suitably after grinding but before granulation the following must meet preferred characteristics:

- specific surface area from 2800 to 6000 cm ² / g

- Sieve residue at 315 microns 0 to

- Sieve residue at 150 microns 0.5 to

- Sieve residue at 100 microns $ 10 to $ 30.

This for each of the named binders

specified preferred characteristics allow a granulation yield from practically $ 100.

With regard to the grain size distribution

Experience has shown that the screen residue is at 150 microns the most critical feature was.

According to a further characteristic of the invention, the grain size distribution is such that the proportion of particles smaller than 20 microns in size does not exceed $ 30.

A third preferred one to consider

The factor is the homogeneity of the vitrifiable mixture in grain form, which is between + $ 1.5 for each grain.

Compliance with this homogeneity factor

has for the purpose that in every grain (its diameter expediently between 8 and 12 mm and whose weight is between 0.5 and 1 g) the overall composition of the vitrifiable

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Finds mixtures with an accuracy of + $ 1.5.

Experience has shown that the vitrifiable mixtures of the above type have the following technical advantages will be obtained:

a) A surprising increase in melt rate of $ 85 to $ 110, depending on the fineness of the mill vitrifiable mixtures within the limits, which with. the granulation in relation to the use of the unground and non-granulated mixture are compatible. Referring to the same unground and ungranulated mixtures the known processes mention a possible increase in melt rate of only $ 30 to $ 60.

b) A given specific surface area of the ground vitrifiable mixture is the degree of wear of the balls and parts of the mill and the energy consumption is lower than if each component were milled separately.

c) Excellent mechanical strength of the grains that remove dust during handling brings in discontinuation.

d) If the mixture is with a binder

is granulated, the above conditions make it possible to achieve a yield of $ 100 when granulating with the granulating plate obtained, which is very important for the economic importance of the process. The invention thus uses the unexpected relationship between the most favorable conditions for the fineness and the grain size distribution for melting the mixture on the one hand and for its granulation on the other.

All of these advantages allow

with the usual sodium lime glasses under the usual manufacturing conditions to double the use of the ovens, or to manufacture glasses at lower temperatures with the same use, This results in lower energy consumption and an increase in the life of the oven. With bad For fusible glasses, such as glasses containing aluminum oxide and silicates, it is sufficient to reach a melting temperature, which is comparable to that of the sodium lime glasses under normal conditions.

The following are non-limiting

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Examples describe certain particular embodiments of the invention.

The invention is primarily applicable to soda lime glasses, which account for about $ 90 of world glass production represent. The main components of these glasses are silica, alkaline and alkaline earth oxides and aluminum oxide and correspond roughly to the following conditions:

SiO ₂ $ 66 to $ 75

Alkaline Oxides

(Na ₂ O, K ₂ O) $ 8 to $ 18

alkaline earth oxides

(CaO, MgO, BaO) $ 6 to $ 15

Alumina 0.5 to $ 3.5

The following binders can be used with these mixtures:

- Sodium and potassium in the form of alkalis, which are 20 to 40 $ of the total alkaline contained in the glass Represent oxides;

- sodium silicate. (SiO, Na ₂ ), which 5 to

Represents $ 20 of the total alkaline oxides contained in the glass ;

- slaked lime Ca (OH) ₂ , which 50 to

Represents $ 100 of the total calcium oxide in the jar.

The use of sodium silicate or slaked lime as a binder, as stated above, does not change the fineness parameters of the ground vitrifiable vegetable if one wants to obtain a granulating efficiency of about $ 100. In contrast, the use of alkaline lyes for a comparable grain size facilitates granulation and enables the melting rate to be increased. example 1

For the yeast production of 1000g mirror glass, its

different constituents in oxide weights have the following percentages:

SiO ₂ 70.70

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₂ O ₃ 0.65

^Ia 2 ° -J 14.65

CaO 9.85

MgO 3.95

SO ₃ 0.20

one assumes the following mixture:

Sand 678.50 g

Limestone 63.71 g

Dolomite 197.48 g

Feldspar 20.70 g

CO ₃ Na ₂ 203.50 g

SO ₄ Na ₂ 21.26 g

SiO ₃ Na ₂ (binder) 30.60 g

This mixture is made in such a way that

after grinding and homogenizing, but before granulating, the following unit conditions are sufficient:

Specific surface area: 4300 cm / g sieve residue at 350 microns: 0 # Screen residue at 150 microns: 1.5 Screen residue at 100 microns: 12.5 The homogeneity of the granules is adjusted to +1.29 δ.

The strength of the granules, after drying in an air stream at 5O ⁰ C is 8 kg.

If one goes with the one in communication 56 of

Seventh International Glass Congress (Brussels 1967) Method of A. and F. PONS the melting rate of the vitrifiable mixture prepared according to the invention comparing with that of the same unground and ungranulated mixtures, an improvement of $ 85 is found.

If you can improve the fineness by grinding finely

brings it to such a value that the specific surface area becomes 5800 cm / g, an increase in the melting rate is obtained from $ 110 versus the same unground and non-granulated mixture.

Above a certain fineness, however, the mowing animal becomes too large and no longer compensates for it

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an advantage obtained from a greater melting rate.

At the same time, experience has shown that the above mixtures according to the invention make it possible to use the granulating plate one (by the ratio of the amount of exiting granules to the amount of powdery material introduced defined) granulation yield of $ 100.

The granules of the present invention have

a remarkable resistance to abrasion, as the following comparative tests have shown:

There were granules corresponding to vitrifiable mixtures as well as granules corresponding to raw cement products made with the same specific surface. These granules were placed in a drum of 100 mm diameter and 225 mm mm in length, the outer surface of which was formed by a sieve with a mesh size of 1.2 mm, and which is 1 Rev / min.

Purely the comparison of the abrasion resistance, printed out The following values are obtained as a percentage of the material emerging from the drum through the mesh of the sieve: Number of revolutions glass granules cement granules 25 0.003 0.3

50 0.005 0.6

75 0.009 1.0

100 0.011 2.5

The measurement of the homogeneity can be carried out on the

Granules can be made by means of a calcimeter into which the material of a previously ground granule is sent, this calcimeter being calibrated in puncture of the complete chemical analysis of the vitrifiable mixture. As an example, it should be stated that the degree of homogeneity of + 1.5 $ required according to the invention for the composition of each granule is to be compared with the degree of homogeneity of + 3 $, which was determined on samples of 100 g of the usual vitrifiable mixtures.
Example 2 .

For the production of 1000 g of a pressure-resistant

Bottle glass, the various components of which have the following percentages in oxide weights:

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SiO ₂ 70.85

Al ₂ O 2.54

₂ 0.19

Pe ₂ O, 0.08

CaO 9.28

MgO 1.57

^Well 2 °! 15.19

κ ₂ ο)

SO, 0.30

the following mixture is assumed:

Sand 625 g

Feldspar 140 g

Limestone 138 g

Dolomite 42 g

Sodium carbonate 203 g

Sodium sulfate 16g

Sodium silicate

(Binder) 30.4 g

After grinding and homogenizing, however

Before granulation, this mixture corresponds to the following fineness conditions :

Specific surface 3600 cm / g particle size distribution:

■ Sieve residue at 315 microns: 0.5 9 ^ sieve residue at 150 microns: 2 fl sieve residue at 5 00 microns: $ 13 homogeneity + $ 1.5.

Example 3 .

To make the same glass as for

Example 1; however, using a 50 # strength sodium hydroxide solution as The following mixture is assumed for the binder:

Sand 697.50 g

Limestone 63.71 g

Dolomite 197.48 g

Feldspar 20.70 g C0, Na _{or similar}

141.95 g 209342/0711

SO ₄ Na ₂ 21.26 g

In addition, an aqueous sodium hydroxide solution (50% soda lye) is applied to the granulating plate in an amount of 131.00 g used.

After grinding and homogenizing, but before granulation, the mixture has the following unit properties:

Specific surface 4150 cm / g particle size distribution:

Sieve residue at 315 microns: 0.5 % Sieve residue at 150 microns: 0.7 $ Sieve residue at 100 microns: 15.5 ^ Homogeneity: + 1.5 #.

After the granules have been granulated and dried at 110 ^° C. for 30 minutes, the strength of the granules is 10 kg.

When you consider the melting speed of the so

When comparing the mixture produced with that of the same unground and ungranulated mixture, one represents an improvement of $ 90 while the granulating yield on the granulating plate Is $ 100.

According to a further characteristic of the invention, the production of vitrifiable mixtures is provided, which can easily hydrolyze the alkaline halides.

For this purpose, the alkaline

Salts (sodium carbonate and sulfate) replaced with sodium chloride. Example 4.

In the context of the above application, the

Production of the same glass as in Example 1 based on the following mixture:

Sand _c 678.50 g

Limestone 77.00 g

Dolomite 178.30 g

Feldspar 20.70 g

Sea salt 301.00 g

Sodium silicate (binder) 30.60 g. After grinding and homogenizing, that has Mixture of the following JP unit properties:

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Specific surface area 4200 cm ² / g particle size distribution:

Screen residue at 315 microns: 0.8 ^ Screen residue at 150 microns: 1.2? S Screen residue at 100 microns: 14.5 1 ° The homogeneity is + 1.3 #.

After drying at 40 ⁰ C, the grain of which still contain water Tfo, a mechanical strength of 8 have kg.

The hydrolysis treatment, which consists in applying to the granule water vapor in a ratio of 500 g to 1 kg per kg of directing the vitrifiable mixtures is carried out for one hour while gradually warming between 200 ⁰ C and 79O ⁰ C. The hydrolysis reaction corresponds to the following formula:

2 NaCl + H ₂ O ^ r = * 2 HCl + Na ₂ O.

The chlorine content remaining in the grains is less than 0.5 $> so that the yield of the hydrolysis reaction is over 99 * 5 ° .

One can do that in the context of this application

explain favorable results obtained by the fact that the granules coming from the granulating plate have a variable Have water content (around $ 10 to $ 15). When heated this Granules, part of the water takes part in the hydrolysis reaction, while the other part is excreted, but in the process Each grain creates small channels that allow the water vapor participating in the reaction to reach the interior of the To penetrate the granule, which also makes a slight exit allow the residual gases. These conditions largely favor the hydrolysis reaction.

The invention is also applicable to borosilicate glasses

applicable. This is how glasses are called whose content of B ₂ O is greater than 5%, while the content of alkaline oxides does not exceed 10%.

The binders that can be used with these glasses are:

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- Soda or Potassium in) $ 50 to $ 100 of the total Porm of lye) contained in the glass

- alkaline silicates J alkaline oxides

- Slaked lime $ 50 to $ 100 of the total in

CaO contained in the glass.

Example 5 «

For the production of 1000 g of a Pyrex glass,

its various constituents in oxide weights as follows to have :

SiO ₂ 79.42 the following mixture is assumed: 795.40 G B ₂ O ₃ 12.60 sand 8.00 G Al ₂ O ₃ 2.92 limestone 46.72 G CaO 0.42 14.60 G Na ₂ O 3.66 223.00 G K ₂ O 0.98 hydrogenated aluminum oxide 72.00 G. CO ₃ K ₂ Boric acid Sodium silicate (binder)

After grinding and homogenizing, however

Before granulation, this mixture has the following unit properties :

Specific surface 3500 cm ² / g particle size distribution:

Sieve residue at 350 microns: $ 0 Sieve residue at 150 microns: $ 0.5> Sieve residue at 100 microns: 14 ° Homogeneity: + $ 1.3.

The invention is also applicable to the so-called

Glasses containing aluminum oxide and silicate can be used, which are the main components in the oxide weights of the glass produced contain :

Silica. $ 55 to $ 80

Alumina $ 10 to $ 30

Oxide from the series MgO, CaO, ZnO 2 to 15 # 209842/0711

Oxides from the series Na ₂ O, K ₂ O ₁ Ii ₂ O 1 to 7 $ The binders that can be used are soda or potassium in the form of lye, or alkaline silicates or slaked lime. Even in small doses, these binders can replace all of the alkaline or alkaline earth carbonates. The aluminum oxide added in the form of kaolin has considerable binding properties even in small doses.
Example 6.

For the production of 1000 g of a glass containing aluminum oxide and silicate, its various components have the following percentages in oxide weights:

SiO ₂ 71.10

18.00 0.30

CaO 0.28

Ha ₂ O 0.63

Li ₂ O 3.55

₃
BrO ₅ 0.30

₃ 1.00

₂ 2.00

ZnO 1.80

ZrO ₂ 1.34

the following vitrifiable mixture is assumed:

Sand 516.00 g

Kaolin 448.00 g

Boric Acid 5.30 g

Limestone 5.00 g

CO ₃ M ₂ 87.53 g

Sb ₂ O ₃ 10.00 g

TiO ₂ 20.00 g

ZnO 18.00 g

ZrO ₂ . 13.50 g sodium silicate (binder) 12.00 g.

Known methods are used to melt and refine this unground and ungranulated mixture a temperature of 1680 ° C is required.

After grinding and homogenizing »but before granulating, this mixture has the following properties:

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22nd 13675 4250 cm / g 0 1 13th fo + 1 , 5 *.

Specific surface: Grain size distribution:

Screen residue at 315 microns

Screen print level at 150 microns

Screen print level at 100 microns

homogeneity

For melting and refining the glass underneath

Output from the above granulated mixture only a temperature of 153O ⁰ C is required.

The invention also has a method for

Manufacture of vitrifiable mixtures of the above type as an object.

According to the invention, this production process is a premixing of the mixture with the following Comprises grinding, characterized in that the large grains supplied by the mill are fed back into it and that the parameters of the grinding process and the returned Amount can be adjusted so that the fineness specified above is obtained for the mixture.

To achieve the desired fineness of the

The following quantities in particular can be influenced in a ball mill:

- the quantity of raw materials supplied at the entrance

- the dimensions of the returned grains and the amount of them

- the speed of the mill

- the active load on the mill (amount and dimensions of the balls).

According to the invention it is provided in particular to return the grains to the mill, their dimensions 150 microns, and a recycle rate of about 2 set to 10. This means in particular that the ratio between the amount of large returned grains and that of the raw material fed to the mill is between the above limits.

The control of the specific surface

can be done quickly with the apparatus LEA and NTJRSE and the particle size distribution by quickly measuring the sieve residue

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a sieve of 150 microns and possibly 100 microns »

The necessary adjustments can be made without difficulty by those skilled in the art for a given vitrifiable Mixture can be determined so that these the inventive Fineness conditions.

Endeavor to establish these conditions

one is committed to maintaining it throughout the manufacturing process.

Milling is preferably followed by drying

ahead of the vitrifiable mixture, which is done either with the flame of a propane burner or with hot air. The temperature of the gases or the hot air varies depending on the moisture content of the raw material between about 150 and 250 ^° C.

According to an advantageous feature of the method according to the invention, the totality of the components of the mixture, including the phase serving as a binder, subjected to Yorm mixing prior to the grinding process

This premixing is preferably carried out by placing these ingredients in a mixer with a vertical Axis (e.g. an EIRICH mixer) during a given time (from e.g. 3 to 5 minutes).

The premix according to the invention is thereby

It is noteworthy that no water is introduced into the mixer since the only aqueous phase present is that of the binder originating when this is formed by an alkaline lye.

According to another feature of the invented

According to the method according _{to the invention} , this comprises a process for homogenizing the mixture coming out of the mill.

This process is carried out appropriately

mixing and stirring the ground raw material in a bed with fluidized bed.

Thanks to this homogenization which precedes the granulation, the granules according to the invention can provided homogeneity conditions can be met more easily.

According to an advantageous feature of the invented

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According to the method, a binder is added to the vitrifiable mixture before grinding and granulation, which at least in part by one of the in the composition of the Oxides contained in the glass are formed.

According to another essential characteristic

According to the invention, the mixture of the constituents of the vitrifiable mixture is fed to a granulating plate for granulation.

This mixture can be sprinkled with water

be, or according to a variant embodiment, if the binding agent is formed by an alkaline liquor, this can serve to sprinkle the remainder of the mixture.

The use of a granulating plate for

Granulating vitrifiable mixtures is known. However, this remedy has so far been practical because of the large sieve residue des ^ eller not applied, while the inventive Preferred fineness conditions allow to obtain an industrial yield on the granulating plate of $ 100, which is an unexpected result.

The critical character of the inventive

must have preferred fineness conditions (specific surface 2800 to 6000 cm / g - sieve residue at 150 microns between $ 0.5 and $ 12) is clear from the experiments below emerge:

a) Specific surface 1500 cm ² / g particle size distribution:

Screen residue at 315 microns $ 1 Screen residue at 150 microns $ 32> Screen residue at 100 microns $ 58. In the laboratory one receives under large

Difficulty with a professional a granulating yield of $ 80. On an industrial scale, the yield is on the granulating plate on the order of $ 20, and the homogeneity is equal to + 10 $, so that the use of the granulating plate is excluded in industrial terms.

However, the use of these granules allows the melting rate of the mixture to be increased.

b) Specific surface 2200 cm / g particle size distribution:

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Screen residue at 315 microns 0.5% screen residue at 150 microns $ 25> Screen residue at 100 microns $ 35. In the laboratory you can use a specialist

granulation with a yield of 100% can be carried out on the granulating plate. The yield is noticeable industrially $ 70, and the homogeneity is + 5%, so the industrial Use of the granulating plate is still excluded.

The granules obtained in this way give an increase in the melting rate compared to the unground non-granulated mixture of | 50 $.

c) Specific surface 6800 cm ² / g grain size distribution:

Sieve residue at 315 microns 0 $ Sieve residue at 150 microns 0 $ Sieve residue at 10μ microns 7 _f 5 $ · In the laboratory, granulation can be carried out with a granulating plate with a yield of close to 100 $. The homogeneity of the grains obtained is + $ 5.

A granulation yield can hardly be achieved industrially

exceeded $ 60. This can be explained by that the powder that is too fine has a tendency, on the granulating plate, to be too small elementary granules with a value between 150 and micron

250 / lying diameter to bake together. Too fine a powder therefore behaves like a powder with a coarser grain size

Here, too, one obtains an increase in the melting rate compared to the loose mixture.

According to a further characteristic of the invention, the granules are subjected to a drying process, before they are either fed to the furnace or to storage. The residual moisture must be pure grains without halides between $ 3 and $ 5. When containing halides Granules can retain this moisture depending on the subsequent treatments vary between $ 0.5 and $ 15.

If the binder used is an alkaline liquor and drying is performed in a drying drum, in which the gas temperature is 130 bis'15O ⁰ C.

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Pure gets a drying time of 30 minutes For example, the residual moisture of the granules is $ 4.

If the binder used is matronsilicate

or slaked lime, drying can help achieve a Residual moisture of $ 3.5 can be done in two ways:

- In a drying drum, gas temperature 50 to 55 ⁰ C, drying time 6 hours

- in a grid
Gas temperature 200 to 25O ⁰ C Dry Time 20 minutes.

The invention also relates to an installation

to practice the above process and to make the granulated vitrifiable mixture.

This system is characterized by

that it contains a ball mill, behind which a dynamic one Voter is arranged, which separates the large grains and a circuit to return these grains to the entrance the mill feeds "

Further features of the invention emerge from the description below referring to the drawing emerged.

Pig. 1 is an overview diagram of the various operations of the "method.

Fig. 2 is a simplified schematic of an industrial plant.

In Pig. 1 are those forming the mixture

Raw materials are shown schematically, namely at 1 the sand, at 2 the limestone, at 3 the dolomite, at 4 the carbonate, at 5 the other ingredients, if any, and at 6 the binder.

These ingredients are fed to stage A, where they experience a premix, whereupon they at B one Drying and subjected to a grinding process at C. If appropriate, stages B and C can be combined with one another because the two operations occur at the same time.

The starting material of the grinding process is fed to a screening stage D, where the large grains are separated (with a diameter of over 150 microns) takes place which

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7 can be returned to the treatment process.

The homogenization stage with a bed with fluidized bed is shown schematically at E, while the Granulation at F and drying at G take place. The dry ones Grains are placed either in the oven H or in the storage room J fed.

The method according to the invention is preferably carried out by means of a system of the type shown in FIG.

in

taken, which below at the same time / one only by way of example given numerical example is described, which concerns the daily production of 250 tons of granules.

In Pig. 2 you can see the mixer at 11 (e.g. an EIRICH mixer with a vertical axis with a capacity of 2 tons).

The mixer 11 receives the vitrifiable mixture with the following composition per ton:

sand 527.7 kg limestone 59.8 kg dolomite 138.7 kg Feldspar 16.0 kg Sea salt 234.1 kg

Moisture content of the mixture 2.4 *.

Sodium silicate
(Binder) 23.7 kg

These ingredients are for 4 minutes

premixed so that the total duration of the process (feed, mix, Emptying) takes 10 minutes, so that the mixer can prepare 11 12 tons per hour.

The premixed material is fed to the buffer sieve 12, the output of which is controlled by an apparatus 13 Dosing is connected, which is feeding one into a ball mill 15 built-in dryer 14 controls.

The dryer 14 contains a Masut burner, the combustion gases of which cause the mixture to be dried. For a vitrifiable mixture with 2.4 $ moisture, the temperature of the combustion gases 15O ⁰ C. The dryer 14 allows the reduction of the moisture of the vitrifiable mixture to 0.5? °>

The mill 15 is a ball mill. The ball mills and their steel accessories can vary depending on their

209842/0711

Adjustment and the moisture content of the raw materials introduce 60g to 400g iron per milled ton. There is no disadvantage to this for bottle glasses and window glasses. Pure white glasses, however, in which the content of FepO should be less than $ 0.025 must, as well as for vitrifiable mixtures containing alkaline halides, the use of non-metallic spheres (e.g. made of sea pebbles or corundum).

The mill has the following parameters, for example:

output 580 hp

Diameter 3 m

Length 6 m

inner ceramic coating

Corundum balls of 20 mm

Diameter.

The mill 15 is set so that the screen residue at 150 microns is less than $ 1.5

The following can be provided for this:

- A filling level (filling level of the mill) of $ 35 corundum balls.

- A speed of 18.4 rpm.

- A large grain repatriation rate of $ 250.

The mill 15 thus produces 12.6 tons in the Hour.

The output of the mill 15 is marked with a Chain hoist 16 in connection, which feeds a bunker 17, which with a dynamic selector with rotating Wings is provided, which acts as a sieve to separate the grains with a diameter of over 150 microns. These grains are returned to the mill 15 through the chute 18 which it sends back to the dryer 14

The ^ est of the mixtures with the right one

Grain size is increased by an air conveyor 19 to a chain hoist 20 supplied, which feeds two identical homogenizing silos 21, 22, which are equipped with a system for blowing in Compressed air are provided, which brings the granular mixture into the state of a bed with fluidized bed. The overpass of the goods from the silo 21 into the silo 22 takes place through

209842/0711

the debris device 23.

The homogenized mixture discharged from the conveyor 24 has the following composition:,.

Specific surface 4200 cm / g particle size distribution;

Sieve residue at 315 microns 0 #

Sieve residue at 150 microns $ 1.3>

Screen residue at 100 microns $ 11.2.

The homogenized mixture is through the

Conveyor 24 fed to the buffer sieve 25, which via a device 26 feeds a granulating plate 27 with controlled dosage, the turntable of which with the one required for the granulation Water is sprinkled.

This water is supplied in such a way that the

The ratio between the water and the moist material is kept constant and e.g. at 16 ^.

The hourly output of the granulating plate 27 is 11.9 tons.

The granules thus formed are supplied to the rotating drum of a dryer 28, which receives the gases from a burner 29, which produce an average room temperature of 52 ⁰ C.

The grains remain in the dryer for 20 minutes. You will be discharged at 30.

The residual moisture of the grains is $ 12.

Their diameter is 8 to 10 mm.

Its mechanical strength is 8 kg.

Their homogeneity is + $ 1.1.

The homogeneity tests were carried out on the granules and on the powder after homogenization. In both cases the result was + $ 1.1.

209842/0711

Claims (1)

hy) Vitrifiable mixture, especially for Sodium lime glass, borosilicate glass and aluminum oxide and silicates containing glass, which is produced by a ground mixture is formed by products such as sand, limestone, dolomite, carbonates and other vitrifiable products. \ i net that an elementary sample of the mixture satisfies the following fineness \ .i conditions: - their specific surface is about between 1500 and 7500 cm / g, and preferably between 2800 and 6000 cm / g; - The grain size distribution of its constituents is such that the screen pressure level with a sieve with a mesh size of 150 microns approximately between $ 0 and $ 35 preferably between $ 0.5 and $ 12. 2.) Mixture according to claim 1, characterized in that it has the shape of granules, thanks to the Addition of a binder which is at least partially formed by an oxide which is made up of those in the composition of the glass contained is selected. 3.) Mixture according to claim 2 for production a sodium lime glass in which the binder is sodium silicate is or slaked lime, characterized in that it has the following Peinheitsbedingungen after grinding and before granulation enough : Specific surface area: 1500 to 7500 cm ² / g and preferably 3500 to 6000 cm ² / g
Grain size distribution: Screen print level at 315 microns 0 to 3 # and preferably 0 to 1 $. Screen printing level at 150 microns $ 0 to $ 35 and preferably $ 0.5 to $ 5. Screen printing level at 100 microns $ 3 to $ 60 and preferably $ 10 to $ 25. Sieve residue at 60 microns $ 15 to $ 75 and preferably $ 20 to 50. 4.) Mixture according to claim 2 for the production of a soda lime glass, in which the binder is an al- 209842/0711 kaiische lye is characterized in that it is after Grinding and corresponds to the following preferred unit codes before granulation: Specific surface area \ 2600 to 6000 cm ² / g grain size distribution: Sieve residue at 315 microns from 0 to Sieve residue at 150 microns from 0.5 to sieve residue at 100 microns from 10 to 5.) Mixture according to one of claims 1 to 4 »characterized in that the percentage of particles with dimensions less than 20 microns is less than or equal to 30 #. 6.) Mixture according to one of claims 2 to 5, characterized in that the homogeneity for each granule about between + $ 1.5 in relation to the total mix lies. 7.) Mixture according to one of claims 2 to 6, characterized in that the mean dimension of the grains is approximately between 8 and 12 mm, the unit weight the granule goes from about 0.5 to 1g. 8.) Mixture according to one of claims 2 to 7f which is to be hydrolyzed before melting, thereby characterized in that at least some of the alkaline salts are formed by sodium chloride, in particular in the form of sea salt will. 9.) A method for producing a vitrifiable mixture according to any one of claims 1 to 8, in which the mixture is milled, characterized in that the large grains are returned to the mill, and that the parameters of the grinding process and the degree of recirculation are set so that the specified fineness for the mixture is obtained. 10.) The method of claim 9 _t characterized in that the return is carried out for the grains having a dimension exceeding 150 microns. 11.) The method according to claim 9 or 10, characterized in that the degree of return of the large Grains about between ^ 2 and 10. 12.) Method according to claim 9 or 10, 209842/071 1 characterized in that all components of the mixture including the phase serving as a binder before Grinding are subjected to a premixing process. 13.) Method according to one of claims 9 to 12, characterized by a homogenization process of the mixture after the grinding process. 14 ·) Method according to claim 13 »characterized in that that the homogenization of the mixture by converting the ground mixture into the state of a bed takes place with fluidized bedding. 15 ·) Method according to one of claims 9 to 14, characterized in that the mixture of ingredients the mixture is fed to a granulating plate for granulation. 16.) Method according to one of claims 9 to 15, characterized in that the components of the mixture be subjected to drying before grinding 17 ·) Method according to claim 15, characterized in that that the formed grains are dried after exiting the granulating plate. 18.) Method according to one of claims 9 to 17, characterized in that at least some of the alkaline salts are replaced by alkaline halides, e.g. sodium chloride, formed, and that these are hydrolyzed in the heat before the vitrifiable mixture is added * 19 ·) Annex to exercise the procedure according to one of claims 9 to 18, characterized by a ball mill (15), behind which a dynamic voter (17) is arranged which separates the large grains and a circle to return them to the entrance of the mill (15) feeds. 20.) Plant according to claim 19, characterized in that that it has a homogenization point behind the mill (15), which through at least one silo (21) is formed which is provided with means for creating a bed with fluidized bed. 21.) Annex for the exercise of the procedure according to Claim 19 or 20, characterized by one behind the mill arranged granulating plate (27). 209842/0711 Blank page