RU2559259C1 - Method for preparing glass batch - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to glass industry, in particular, to the methods for preparing glass batches. The raw materials were co-ground until at least 50% of the ingredients were 10 mcm, the resulting mix was compacted and heated at the rate of 5 to 20°C per minute, avoiding foam formation, to a temperature of 700-1300°C and kept at a maximum temperature for 3 hours maximum. The grinding can be accomplished either by wet or by dry grinding. The batch moisture content for grinding was between 40 and 80%. The dry ground batch was compacted within 1 hour upon completion of grinding process.

EFFECT: achieved microhomogenous glass batch with high melting characteristics, maintaining batch homogeneity, avoiding its stratification, dusting and losses in storage and during transportation.

3 cl, 4 ex

Description

The invention relates to the glass industry, in particular to methods for preparing a mixture for the production of glass.

A known traditional method of preparing a glass mixture by drying, grinding, sieving (sand - sieve No. 08; chalk - sieve No. 1.1; dolomite and limestone - sieve No. 09; sulfate - sieve No. 1.2; soda - sieve No. 1, 1; pegmatite and feldspar - sieve No. 07, etc.), weighing the raw materials (according to the recipe of the charge), loading them into the mixer, moistening and mixing (Pavlushkin NM Chemical technology of glass and glass materials: Textbook for universities - M.: Stroyizdat, 1983, p. 94-100).

The disadvantages of this method of preparing a glass mixture are:

- stratification of the obtained bulk charge during its transportation and storage;

- dusting of the charge when loading into a glass furnace;

- low activity of raw materials, requiring high temperatures when cooking glass, and also increasing the cooking time;

- not high uniformity of the resulting glass.

There is also known a method of preparing a glass charge (Eurasian patent No. 004463, С03В 1/00, 2004) by dispersing a traditionally prepared glass mixture to a particle size of at least 10 μm, the dispersion being carried out with moistening up to 30%, and the moisture content of the charge is maintained until loading into a glass melting furnace.

The disadvantages of this method of preparing a glass mixture are:

- wetting the slurry to 30% water according to physicochemical parameters is not suitable for all charge compositions, since coagulation-crystallization interaction may occur during grinding with insufficient moisture, leading to complete agglomeration of the slip mass,

- feeding the mixture with 30% humidity to the glass melting furnace will lead to a significant increase in the content of [OH ^- ] groups in the glass, which will entail a lower degree of silicon-oxygen motif cohesion, and less chemical stability of the glass. Closest to the claimed is a method of preparing a glass mixture (Eurasian patent No. 014546, С03В 1/02, С03В 19/02, 2010) by mixing, moistening up to 20-22%, grinding in a ball mill for 4-6 hours components, and drying the resulting slurry, resulting in the formation of solid briquettes.

The disadvantages of this method of preparing a glass mixture are:

- wetting the slurry to 22% water according to physicochemical parameters is not suitable for all charge compositions, since coagulation-crystallization interaction may occur during grinding with insufficient moisture, leading to complete agglomeration of the slip mass inside the mill,

- drying the slip at temperatures of 100-150 ° C cannot provide high contact strength between the batch particles in the briquette; therefore, during transportation, the briquettes will crack and crumble, which will lead to loss of the batch, reduction of its uniformity, dusting and delamination.

The objective of the invention is to obtain a homogeneous at a micro level glass mixture with increased cooking ability, eliminating delamination and dusting of the glass mixture, ensuring the preservation of the achieved high level of uniformity of the glass mixture during its transportation and storage.

The problem is solved as follows:

The raw materials are subjected to joint grinding until at least 50% of the components have a size of not more than 10 microns, the resulting mixture is compacted, then heated at a speed of 5 to 20 ° C per minute, preventing foaming, to a temperature of 400-1300 ° C , and maintained at a maximum temperature of not more than 3 hours. Grinding is done by wet or dry method. Wet grinding is carried out at a moisture content of the mixture from 25 to 80%. When grinding by dry method, the charge is compacted no later than 1 hour after the end of the grinding process.

Fine grinding, on the one hand, leads to a decrease in the grain size of the charge, which increases the contact area between its components and, accordingly, increases the yield of the products of their interaction. On the other hand, the intense mechanical action that occurs during grinding due to the accumulation of structural defects leads to an increase in the internal energy of the substance. This reduces energy costs for transfer processes, chemical interaction, phase transformations, and more. In addition, during joint grinding, the mixture of the components of the mixture is mixed, and the homogeneity of the resulting mixture is at the level of grinding fineness, in our case, at the micro level. Thus, joint fine grinding ensures the transfer of a significant portion of the homogenization process from the furnace to the stage of preparation of the charge. As a result, the glass mixture obtained after the grinding operation has homogeneity at the micro level, increased chemical activity and increased cooking ability.

The stage of additional heat treatment to a temperature corresponding to the end of silicate formation, following grinding and compaction, allows:

firstly, to ensure the interaction of components with their maximum activity, i.e. at lower temperatures and less energy;

secondly, due to the sintering of the mixture to obtain a workpiece of high strength, which will maintain the achieved uniformity of the briquette, exclude its destruction, prevent dusting, delamination and loss of the mixture.

The gradual heating of the charge ensures the consistent passage of all chemical reactions between its components, including those reactions during which gaseous substances are released. Reducing the gas content of the mixture leads to easier clarification during cooking. Heating must be carried out at a rate of temperature rise that does not cause foaming of the briquette, in other words, does not lead to the retention in the charge of an excess amount of gas that impedes clarification.

The implementation of the method.

Example 1

The components of the glass mixture - 61.75 mass. % SiO ₂ , 20.75 wt. % Na ₂ CO ₃ , 17.5 wt. % CaCO ₃ served in a planetary mill where they are moistened to 50 mass. % water and joint grinding to a state where 50% of the grains of the mixture have a size not exceeding 10 microns. Additive 50 mass. % water is sufficient to exclude the formation of a coagulation structure in the suspension of the charge. The mill has a lining based on SiO ₂ , and grinding bodies of the same composition. This method of preparation of the mixture involves the adjustment of the mixture taking into account the grinding of the lining material and grinding media. The resulting slip mass is poured into metal pallets and dried in a tunnel oven at a temperature of 250 ° C, during which batch briquettes are formed.

Dried briquettes will be placed in refractory boats and heat treated in a gradient tunnel furnace. The highest firing temperature is 900 ° C, it is sufficient to shrink the material and complete the stage of silicate formation. The rate of temperature rise during the promotion of briquettes through the furnace (maximum heating rate of the material) is 10 ° C per minute, which does not cause foaming of the briquettes.

Example 2

The components of the glass mixture - 49.1 mass. % SiO ₂ ; 35.5 mass. % PbO; 14.2 mass. % K ₂ CO ₃ ; 1.2 mass. % N ₂ CO ₃ served in a planetary mill where they are moistened to 40 mass. % water and joint grinding to a state where 50% of the grains of the mixture have a size not exceeding 10 microns. Additive 40 mass. % water is sufficient to exclude the formation of a coagulation structure in the suspension of the charge. The mill has a lining based on SiO ₂ , and grinding bodies of the same composition. This method of preparation of the mixture involves the adjustment of the mixture taking into account the grinding of the lining material and grinding media. The resulting slip mass is poured into metal pallets and dried in a tunnel oven at a temperature of 250 ° C, during which batch briquettes are formed. Dried briquettes will be placed in refractory boats and heat treated in a gradient tunnel furnace. The highest firing temperature is 700 ° C, it is sufficient to shrink the material and complete the stage of silicate formation. The rate of temperature rise during the promotion of briquettes through the furnace (maximum heating rate of the material) is 5 ° C per minute, which does not cause foaming of the briquettes.

Example 3

The components of the glass mixture - 36.8 mass. % SiO ₂ ; 27.7 mass. % Al ₂ O ₃ ; 26.3 mass. % SrCO ₃ ; 9.2 mass. % TiO _{2 is} fed to a planetary mill where they are hydrated to 60 mass. % water and joint grinding to

state when 50% of the grains of the charge have a size not exceeding 10 microns. Additive 60 mass. % water is sufficient to exclude the formation of a coagulation structure in the suspension of the charge. The mill has a lining based on SiO ₂ , and grinding bodies of the same composition. This method of preparation of the mixture involves the adjustment of the mixture taking into account the grinding of the lining material and grinding media. The resulting slip mass is poured onto metal pallets and dried in a tunnel oven at a temperature of 250 ° C, during which batch briquettes are formed. Dried briquettes will be placed in refractory boats and heat treated in a gradient tunnel furnace. The highest firing temperature is 1300 ° C, it is sufficient to shrink the material and complete the stage of silicate formation. The rate of temperature rise during the promotion of briquettes through the furnace (maximum heating rate of the material) is 20 ° C per minute, which does not cause foaming of the briquettes.

Example 4

The components of the glass mixture - 61.75 mass. % SiO ₂ , 20.75 wt. % Na ₂ CO ₃ , 17.5 wt. % CaCO ₃ is fed to a planetary mill where they are dry milled to a state where 50% of the grains of the charge have a size not exceeding 10 microns. Due to the fact that materials with different hardness during grinding behave differently (soft materials, such as talc, chalk, etc., envelop harder particles, preventing them from dispersing), for their most complete dispersion and mixing, the loading of raw materials of different hardness is carried out at different times. First of all, for preliminary grinding, the hardest raw materials (quartz sand, feldspars, etc.) are fed, then the remaining softer components are added to them. The mill has a lining based on SiO ₂ , and grinding bodies of the same composition. This method of preparation of the mixture involves the adjustment of the mixture taking into account the grinding of the lining material and grinding media.

Immediately after grinding, the mixture is fed to pressing, where it is shaped into briquettes. Next, the briquettes are placed in refractory boats and heat treated in a gradient tunnel furnace. The highest firing temperature is 900 ° C, it is sufficient to shrink the material and complete the stage of silicate formation. The rate of temperature rise during the promotion of briquettes through the furnace (maximum heating rate of the material) is 10 ° C per minute, which does not cause foaming of the briquettes.

The proposed method of preparing the mixture allows to obtain a glass mixture homogeneous at a micro level, which has an increased cooking ability, as well as to maintain the achieved level of uniformity of the glass mixture, to avoid delamination, dusting, and loss of the mixture during storage and transportation (even over long distances). Together, this will create a centralized production of a glass charge and provide for the needs of many glass manufacturers.

Information sources

1. Pavlushkin N.M. - Chemical technology of glass and glass. - M.: Stroyizdat, pp. 94-100.

2. Eurasian patent No. 004463, С03В 1/00, 2004

3. Eurasian patent No. 014546, C03B 1/02, 2011

Claims (3)

1. A method of preparing a glass mixture by mixing, grinding raw materials, followed by compacting and drying the mixture, characterized in that the mixture is crushed until at least 50% of the components reach a size of no more than 10 microns, and the resulting mixture is additionally heated at a speed of 5 up to 20 ° C per minute to a temperature of 700-1300 ° C and maintained at this temperature for no more than 3 hours. 2. The method according to p. 1, characterized in that the grinding is carried out at a moisture content of the mixture from 40 to 60%. 3. The method according to p. 1, characterized in that the grinding is carried out by the dry method, and the charge is compacted no later than 1 hour after the end of the grinding process.