WO2011048446A1

WO2011048446A1 - Granulated batch for foam glass and method of production of said granulated batch

Info

Publication number: WO2011048446A1
Application number: PCT/IB2009/055994
Authority: WO
Inventors: Vladimir Valentovich Jegorov; Sergej Borisovich Rodin; Semion Sergejevich Rodin
Original assignee: Uab "Stikloporas"
Priority date: 2009-10-22
Filing date: 2009-12-30
Publication date: 2011-04-28
Also published as: RU2439005C2; RU2009139009A

Abstract

The following inventions fall into the category of production of light bulk construction material based on glass, in particular, the means of production of foam glass or foam silicate commercially marked as e.g. PENOSTEK, that are also heat-insulating and fire-resistant materials and can be used, for example, for thermal insulation and fire protection of vehicles, buildings, and equipment, as an aggregate added into concrete constructions and in other areas of technology. The invention suggests granulated batch for foam glass production containing fine ground glass with particles of maximum 65 microns (65-88 % by weight of the batch), liquid glass (5-15 % by weight); foaming agent that includes glycerin with CaCO₃ or MgCO₃ or BaCO₃ or SrCO₃ (1-2 % by weight); water (5-15 % by weight), kaolin or kaolinite (1-3 % by weight). This set of ingredients in the mentioned proportions within the batch is original and ensures more homogeneous mixing and better quality of the foam glass produced from glass waste that is a result of household waste recycling and utilization. In fact, the following technical solutions are aimed at solving environmental issues and the issues of waste utilization.

Description

GRANULATED BATCH FOR FOAM GLASS AND METHOD OF PRODUCTION OF SAID GRANULATED BATCH

Technical Field

[1] The following inventions fall into the category of production of light bulk construction material based on glass, in particular, the means of production of foam glass or foam silicate commercially marked e.g. as PENOSTEK, that are also heat-insulating and fire-resistant materials and can be used, for example, for thermal insulation and fire protection of vehicles, buildings, and equipment, as an aggregate added into concrete constructions and in other areas of technology.

Background Art

[2] Positive features of foam glass, areas of its application, its production technology have been widely acknowledged. This foam glass heat-insulating porous material is known to be produced mainly by the means of sintering fine glass powder with gasifier and usually comes in a form of small-sized granules used e.g. as aggregate. There are various granulated foam glass production methods, such as crushing and grinding of utilizable glass or glass products to form granulated fine disperse glass powder for further production of foam glass batch by adding foaming agent (for example, see Demidovich B.K. Production and Application of Foam Glass. Ed. Nauka i Technika, Minsk, 1972, pages 100-122; Shil F. Foam Glass. Ed. Construction Literature

Publishing House, Moscow, 1965, pages 14-18; patent RU2307097, C03C 11/00, 27.09.2007).

[3] The requirement to describe foam glass production, briefly review batch composition and its production methods, highlight the information on the analogues causes certain inconvenience; therefore, descriptions of references of the widely accepted analogues of the suggested technological solutions have been combined according to the issue.

[4] There are various additions, compositions, mixtures, and components used for

production of batch that serves as the basis of the end-product, i.e. foam glass. Two of the most effective batch compositions and production methods are: the first - specific founding of glass of the required chemical composition; the second - using composition based on the glass powder which is the product of cullet (waste glass) of heterogeneous or homogenous chemical composition, and selection of gasifier with the subsequent foaming while heating the complete mass of glass. Glass powder is produced either by the means of grinding, or by using melted glass masses (for example, see patents RU2023982, C03C 11/00, 30.04.1995; US4192664, C03B 19/08, 1980; US3403990, 65-22, year 1968), or crushed window, container glass etc. (e.g. RU2149146, C03C 11/00, 20.05.2000; RU2051869, C03C 11/00, 10.01.1996;

US4198224, C03B 19/08, 1980). In certain cases, finely crushed melted glass is used for foam glass production (RU2361829, C03C 11/00, 27.11.2008; DE2010263, C03C 11/00, 1979).

[5] The choice of method and composition for foam glass production depends on a range of independent features and local conditions, such as availability of the required raw materials,

[6] ecological issues, composition and nature of the utilized waste, cost of energy

resources, demand and cost-efficiency of certain foam glass and characteristics. The variety of factors is the reason for a wide range of specific compositions and technologies in this area of production.

[7] Therefore, among the closest analogues of the suggested composition of granulated batch for foam glass production, batch that proves efficient use of carbonates, i.e. the batch containing ground glass and carbonate gasifier, can be mentioned (patent RU2266874, C03C 11/00, 10.11.2003). However, analogue possibilities of utilizing glass waste have not been discussed with the proper attention.

[8] One of the closest analogues of methods of batch production for foam glass is a

method that involves mixing glass-forming component and powder-like additives with carbon-containing gasifier. Glass-forming component of the gasifier is the water alkali solution of sodium and/or potassium (liquid glass) silicate, the concentration of which amounts to 50-70 % (weight percent), while fine cullet glass is used as the powder-like additive (patent RU2255058, C03C 11, 27.06.2005). Nevertheless, the possibilities of utilizing heterogeneous glass waste have not been discussed as well.

[9] Using glass waste and occasional glass waste in construction material production is considered to result in a wide range of the raw material that differs in its composition and features. Glass of different composition and sort is known to differ significantly in its physicochemical and technical characteristics, and waste management for extracting glass waste of similar characteristics is inefficient. At the same time, most common foam glass production technologies can be used only with raw materials of stable characteristic rather than occasional glass and waste glass. World-wide environmental campaigns have been demanding new approach and development of new energy efficient waste management technologies.

[10] The following inventions and their technological effectiveness are, first of all, aimed at solving environmental issues related to utilization of various glass waste including heterogeneous (by composition and form) waste; ensuring efficient utilization and possibility to produce foam glass by using non-standard glass of variable composition, at the same time constantly improving the quality of end-products (construction materials that contain foam glass); and providing wider range of glass waste management technologies.

Based on the considered issue, the set technological outcome, and all the essential features of the inventions present in the closest analogue-prototype of the suggested batch composition and its production method, granulated batch for foam glass production and its production method can be presented according to the method (technology) of granulated foam silicate production (patent RU2291126, C03 C 11/00, 2007-07-10).

The granulated batch for the foam glass contains fine ground glass, carbonate agent, liquid glass, and water, as mentioned in the method.

This well-known method of foam silicate gravel production is formed of several stages: the stage of drying and secondary crushing of the cullet and pore agent (foaming agent, gasifier) to form the mixture of carbonate and carbon materials, e.g. at mills; ground batch feed to the storage hopper; dosage and pore formation prior to mixing; mixing of batch in drum mixers, granulation of batch by using liquid (soluble) glass water solution and by e.g. drum granulator; preliminary drying and sintering of the produced batch granules. The concentration of carbonate pore agent mixed with the carbon agent may amount to 5 to 95 % (weight percent). The produced granulated batch is further fed to the furnace for forming foam silicate gravel at the temperatures of 300 to 900 °C.

The description of the established method (patent RU2291126) is considered to be fairly informative. Nevertheless, the description and references to the outbound materials lack deeper insight into features related to waste management and instability of raw material and end-product characteristics. For example, the range of fluctuations of raw material density has been omitted, whereas raw material density is one of the most essential characteristics of cullet and is apt to significant changes that probably are the reason for variations of pore agent concentration from 5 to 95 % (weight percent). Other optimum numerical indicators of all the ingredients of raw material have not been mentioned as well. This is the obstacle in application of the discussed method, as well as other known methods, when it comes to managing glass waste of various characteristics. This is also related to the issues of determining the complete batch composition, if you have to deal with occasional cullet lot and production technology to form granulated product from this cullet.

Disclosure of Invention

Technical Solution

As noted above, the inventions and their technological result are, first of all, aimed at solving environmental issues that are faced when utilizing various glass wastes, producing batch and construction foam glass from these secondary raw materials; cost reduction and improvement of end-product quality given the wide range of types and characteristics of the feedstock (waste).

[17] The composition of granulated batch shall include the following prototype ingredients: fine ground glass (refined cullet as a result of e.g. waste utilization), liquid glass, foaming agent (pore agent), including carbonate agent, and water (e.g. in liquid glass solution). Beyond the prototype, the composition also includes glycerin and kaolin or kaolinite. The concentration (weight percentage, %) of the mentioned ingredients is as follows:

[18] Liquid glass 5-15;

[19] Foaming agent, including glycerin 1-2;

[20] Water - 5-15;

[21] Kaolin or kaolinite 1-3;

[22] Ground glass (sieved) - the rest.

[23] CaC0₃ or MaC0₃ or BaC0₃ or SrC0₃ are used as carbonate foaming agent.

[24] In case average density of the used ground glass increases, concentration of glycerin should be reduced and carbonate agent of higher specific density should be used.

[25] The method batch production for foam glass includes the stage of ground glass production with possible preliminary refinement to remove additives and impurities during cullet washing with water and drying; further crushing; dosage and mixing of ground glass with carbonate foaming agent and glass forming component (liquid glass water solution); further granulation and partial drying of the acquired granules, as described in the prototype. Moreover, this batch production method involves preliminary sieving of solid fine batch components to extract particles of maximum 5 microns; measuring

[26] average density of ground glass; producing liquid glass water solution and glycerin water solution with carbonate component (for example, calcite or magnesite forming foaming agent), each solution in separate containers paying attention to the prescribed proportions with the maximum water content amounting to 5 % of the total batch weight. Further, both liquid glass solution and foaming agent are independently mixed together by simultaneously and gradually feeding them in the prescribed doses to the mixer of e.g. planetary-screw type with the ground pre- wetted glass being already in the mixer. The ingredients are mixed to form the desired homogenous wet batch. (It is possible to add water or liquid glass solution to the mixture). The batch, together with water, is further fed to the plate granulator. Formed granules are further fed to the furnace for preliminary sintering. The concentration (weight percentage) of components in batch weight ready for sintering is as follows: liquid glass and water - 5-15 % each; foaming agent - 1-2 ; ground glass - the rest.

[27] The suggested batch production method may also involves the stage of sorting

granules by size and adding 1-3 % (weight percent) of kaolin or kaolinite powder that covers the surface of granules during e.g. their powdering. The stage takes place after the granules have been produced in the granulator and prior to preliminary sintering. It is also recommended to measure the proportion of components under maximum and minimum allowed density of ground glass during batch production for experimental purposes. The proportion should be measured with reference to liquid glass density. It is also recommended to measure the average density of batch mixture after the mixing stage, and adding to the mixture a minimum amount of water sufficient to receive wet granules. The average density is considered to be a set value. The size of granules and quantity of batch is further adjusted by increasing the feed of water within the set limits and controlling the density of the batch during its production. At the same time, proportion of glycerin and foaming agent can be increased by decreasing the density of the batch. On the other hand, in the case of increased density of the batch, the proportion of glycerin can be decreased, in this way controlling the quality of the mixture.

[28] It is important to stress the achievements in technological results, because until

recently, little have environmental issues and practical useful utilization of secondary raw materials and waste been considered with proper respect. At present, the significance of the issue has been accepted world-wide. The suggested plan also contains costly inefficient technologies that facilitate waste utilization and environment protection, which proves that these technologies should be regarded as progressive. Producing such construction materials as granulated foam glass by using good quality standard raw materials and widely- accepted technologies would be easier; however, the suggested inventions offer improvement of utilization technologies that have been proven to be industrially applicable by the experiments. The set of major essential features declared in the independent expressions of the formulae of the inventions has not been discovered during data patent information search. This helps distinguish dependent expressions of the formulae and prove the novelty criteria related to the declared group of inventions. In terms of technology level, the choice of analogue- prototype should be mentioned. The analogue-prototype is fairly close to the already established technical solutions in its essence and implementation. On the other hand, it contains a great deal of informational background that reveals previous insufficient attention to utilization and various waste recycling, fast technological process of foam glass production in case of unpredicted significant change of raw material characteristics and foaming process. For example, questions related to the necessity of

[29] monitoring such characteristics as density of the processed glass (which can change 2-3 times within one cycle) have not been discussed in a proper way, while methods of managing such processes are practically absent in IPC documentation. This leads to the conclusion that despite the relative awareness of the methods of production of granulated foam glass and its ingredients, certain day-to-day operational management of technological operations and components of batch (for example, in the case of rapid change of the nature of processed household waste) have not been studied yet. This means that the given inventions suggest new approach in the development of existent technologies, which points to the difference between the suggested technological solutions and the already established ones, and proves the conformity of these inventions with the criteria on technology level.

Best Mode

[30] The main aim of the given inventions is to provide the possibility to produce quality transportable granulated batch for further production of quality foam glass by using occasional waste and glass waste at minimum production cost. The main difficulty of implementation of the idea is the fact that production of high quality foam glass requires melting glass of the constant pre-determined composition according to established standard procedure. However, standard cheap procedure of waste utilization cannot ensure constant pre-determined composition during batch production and further production of glass. The quality of the product is also determined by fineness of ground components, which also requires process management. The suggested inventions provide constant control of produced batch weight and density with reference to the density of the ingredients (which is also the main criterion of their selection).

[31] According to the invention, the suggested granulated batch for foam glass contains only fine ground glass, liquid glass, water, and mixture of carbonate ingredient and glycerin as the foaming agent, and kaolin or kaolinite of the following proportions (weight percent): liquid glass - 5-15 ; water - 5-15 %, foaming agent, glycerin included - 1-2 ; kaolin or kaolinite - 1-3 ; sieved ground glass - the rest, 65 to 88 %. CaC0₃ or MaC0₃ or BaC0₃ or SrC0₃ of up to 1% mixed with glycerin are used as carbonate ingredient. Such composition and the determined concentrations are not random. Significant weight of water and liquid glass dissolved in it are partially related to the fact that the density and weight of these two constituents may considerably influence the average density and weight of the complete batch, thus providing the possibility of compensating for the deviations of cullet density. According to the Great Soviet Encyclopedia (GSE, volume 24-1, 1976), the density of glass may change within the range of 2200 to 8000 kg/m₃ (less in the field) depending on the components of glass. Moreover, density of ground glass and other components of the same sort change according to the fineness of crushed ingredients. The density of liquid glass and water may differ 1.5 times; however, their density is much lower than the density of the glass. In the case of the determined proportions, liquid glass and water may considerably decrease the density and adjust other physical features of the whole batch, penetrate between the pores of the ground glass. During mixing process, this feature significantly influences homogeneousness of the produced batch and distribution of the foaming agent, which allows the liquid glass and water act as process regulators by changing their proportions within the set limits. This may apply, for example, if batch density is

[32] to be adjusted. Glycerin, the same as liquid glass, possesses good dissolubility in water qualities, and, as proven by tests, it also stimulates formation of homogeneous mixture and, being a foaming agent, provides favorable environment for gradual penetration of carbonate ingredients into the batch. According to preliminary data, in the case of increased density of cullet, carbonate foaming agents of higher density can be used, for example, BaC0₃ (witherite) is recommended to replace CaC0₃, as the density of the former is 1.5 times higher. The choice (and proportions) of kaolin or kaolinite (1-3 %) is based on the tests and ensures better quality of batch and foam glass granule surface. Such composition and stated proportions of ingredients have not been tracked during patent search, which allows assuming the novelty of the composition.

[33] The suggested method of granulated batch production can be presented as the

following list and description of determined sequence of technological operations:

[34] Al. The primary stage of implementation of the suggested method is waste collection and management, which, though excluded from the suggested formula of the invention, is the initiating part that sets all the further operations related to production and quality management of the batch, the quality of which is directly related to the quality of raw material. Waste collection includes primary selection and storage of various glass wastes that are visually suitable for recycling. Further, the selected waste, e.g. dirty jars and bottles, is stored in washing containers (reservoirs with reinforced floor and a device resembling a power hammer for crushing glass). Crushing is proceeded by pressure washing of the cullet with industrial water. Water level inside the container can exceed the level of cullet (immersive washing). After soaking, the water is drained preferably only from the upper level and the floor of the reservoir, and filtered for reuse and possible repetitions of the operation.

[35] A2. Cullet is further crushed and washed to acquire cleaner and finer fractions. At this stage, other ball mill type devices and special containers with washing equipment, where finer crushing of cullet to form ground powder is performed, are used. Special attention is paid towards refinement of the cullet of any dirt or additives that are unacceptable in foam glass production. Thus, cullet is forwarded through e.g. magnetic or other separators to remove metal or other additives and contaminated glass fragments of the cullet that are not suitable for processing. The acquired cullet is filtered through large-scale sieves and further dried and, possibly, sent in for secondary separation.

[36] A3. In order to acquire maximum 5 microns particles of the ground glass, fine

crushing of the collected glass is performed again in special cullet crushers, ball or hammer mills, fine grinders, with possible re-sorting, washing and drying of glass powder in special washing and sorting machines, breaking into fractions of 3, 4, 5 microns, for example, by sieving and accumulating in storage hoppers with batch- weighers, where the average density of ground glass is also measured.

[37] A4. Storage hoppers with batch- weighers also serve as containers for preparing water supplying doses of water to the mixers. The proportion of water in relation to the weight of glass powder is 20 % per one (1) feed (with certain reserve amount).

[38] At this stage, it should be noted that ingredient proportions mentioned in the description and formula of the inventions are applicable to the total weight of all components of one feeding lot, taking into account possible weight tolerance and deviations. However, weight and volume batching of ingredients is recommended to be based on the fixed weight of cullet in 1 lot. Total weight of 1 cullet lot

[39] that is marked and referred to as full loading is approximately 20-30 % higher than the weight of glass in it. This is accordingly noted and included into in-line documentation.

[40] A5. Loading of storage hoppers and other operations are simultaneously accompanied by dosage of glycerin (pore agent) in separate containers in certain volumes (batching), e.g. 0.1; 0.2; 0.4 % of glass powder weight in 1 load.

[41] A6. Loading of storage hoppers and other operations are simultaneously accompanied by dosage of carbonate foaming agent (CaC0₃ (calcinite or chalk) or MaC0₃ or BaC0₃ or SrC0₃). Usually, only one certain carbonate, for example, calcinite, is selected for one load. However, in case of several various loadings, even if they take place during one working shift, different carbonate foaming agents of different volumes might be used depending on the features of cullet and batch requirements. This requires preparation and availability of various batches with different ingredients in the warehouse, for example, ingredients in certain volumes (batching) of 0.1 ; 0.2 ; 0.4 % by weight of glass powder in 1 load.

[42] A7. Operations A5 and A6 are proceeded by batch mixing of glycerin and selected carbonate as 1: 1, forming standard 1 % by weight of glass powder in 1 load, to combine foaming agent from different containers. During the process, the volume can be doubled while preserving the proportions of ingredients or while changing the proportion of one of them based on certain parameters of batch.

[43] A8. Loading of storage hoppers and other operations are simultaneously accompanied by dosage of liquid glass (binding) in several batches, for example, 1, 2, 5, and 10 % by weight of glass powder in 1 load. It is recommended to produce batch in cycles, in separate lots; however, continuous cycle is possible if stored raw material is used and lots are combined.

[44] A9. Loading of storage hoppers and other operations are simultaneously accompanied by production of kaolin or kaolinite powder in separate containers of 1 % by weight of glass powder (3 doses per 1 lot) for batch powdering or rolling (for visual consumption control).

[45] Al l. Operations A4 and A8 are proceeded by preparation of liquid glass water

solution by mixing water with liquid glass in set proportions, water weight being less than liquid glass weight and constituting maximum 5 % of the total estimated weight of batch (per 1 loading). This is based on the fact that part of water is used for preliminary wetting of glass powder, and part of water is added in the course granulation.

[46] A12. The next stage is production of batch granules. The mixer of e.g. planetary- screw type is thoroughly cleaned and filled with estimated weight of ground glass (batching) of the known dry density and a small dose of water from the feeder. Water is necessary to remove dust and stimulate mixing. Water mixtures of liquid glass and foaming agent are poured into separate small-size mixers. The mixers and the main mixer are actuated, and, during the mixing process, liquid glass and foaming agent solution are added into the ground glass in the main mixer for thorough mixing. During the mixing process, samples of the acquired batch lumps are taken every 10-15 minutes. The lumps form as the result of operation by screw auger of the mixer, with the pitch of the screw being set according to the required diameter of granules. Density and volumes of lumps are measured by weighting and immersion into water. Quality of the mixture; its homogeneousness; the need of water and liquid glass addition within the set limits in the mixer and the granulator; and the need of additional mixing

[47] are determined by the density and visual quality of the batch. Total working time of the mixer may amount to 20-40 minutes per 1 loading. Temperatures range within the positive temperature mode.

[48] A13. The batch is further fed from the mixer to the granulator e.g. of plate type, where the final form of granules is created by rolling. The process can be implemented by using inclined pivot rotation plate. During granulation process, water necessary for wetting and smoothing of granule surface is fed to the granulator. Simultaneously or a little later, doses of kaolin or kaolinite are fed by parts to the granulator. Kaolin or kaolinite performs the function of rolling material for batch during granulation. Total time of granulation amounts to 15-20 minutes per 1 cycle. The operation of the mixer and the granulator is preliminary tested.

[49] A 14. The material prepared in the plate granulator is dried at the temperature ranging from 150°C to 400°C for 10 to 60 minutes e.g. in tunnel furnace with the aftercooling. This may lead to overheating of working premises; therefore, sufficient ventilation for keeping the temperature within +10°C to + 40°C is required.

[50] A15. Operations 12, 13, and 14 are proceeded by e.g. visual sorting the acquired granules by size and quality. The process of granule production is completed by drying the granules. The granules can further be fed to the heating furnace for foaming to produce foam glass or temporarily stored at the warehouse.

[51] A 16. The distinctive feature of the suggested technology is its anticipation of

possible instability of characteristics of raw material as a result of waste utilization. Major parameters subject to changes are densities of the ground glass and, accordingly, of the batch. The process is managed by measuring current density of the batch, with the density of the ground glass being the determining parameter; and by changing the proportions. According to the tests, in the case of decreased density of the batch and ground glass, the proportion of glycerin, liquid glass, and water should be decreased within the set limits. In the case of increased density, the proportion of the ground glass should be increased.

[52] The above set of operations forms the process of production of the product

(granulated batch and foam glass) that meets high quality standards, which shows the technological result of the invention. Tested system and equipment have been created for implementation and approbation of the suggested technologies. Production process does not require large areas; however, single complex of collection and management of other types of household waste, supply stability and recycling are required. The set and sequence of technological operations can also be ensured by standard or modified equipment of different manufacturers; however, this requires certain test operations related to various raw material types and certain equipment.

Claims

[Claim 1] 1. Granulated batch for foam glass production containing fine ground glass, liquid glass, foaming agent, carbonate agent, and water, c h a r a cterizedin that it contains glycerin that acts as a foaming agent, and kaolin or kaolinite in the following proportions (weight percent): Liquid glass - 5-15;

Water -5-15;

Foaming agent, including glycerin - 1-2;

Kaolin or kaolinite - 1-3;

Ground glass (sieved) - the rest.

2. Batch according to claim 1, characterized in that it contains carbonate foaming agent CaC0₃ in proportion up to 1 % in the mixture with glycerin.

3. Batch according to claim 1, characterized in that it contains carbonate foaming agent MaC0₃ in proportion up to 1 % in the mixture with glycerin.

4. Batch according to claim 1, characterized in that it contains carbonate foaming agent BaC0₃ in proportion up to 1 % in the mixture with glycerin.

5. Batch according to claim 1, characterized in that it contains carbonate foaming agent SrC0₃ in proportion up to 1 % in the mixture with glycerin.

6. Method of batch production for foam glass comprises the following stages: production of ground glass with possible prerefining from additives and dirt during cullet washing and drying process; further refinement, dosing, and mixing of cullet with carbonate foaming agent, and adding glass forming component as liquid glass water solution, further granulation and partial drying of the acquired granules, c h a r a cterizedin that solid refined components of batch are pre-sieved to extract particles of maximum 5 microns; average density of ground glass is measured; liquid glass water solution is prepared in separate container and certain part of water solution of glycerin and carbonate component (limestone or magnesite) that act as foaming agent are added into the container; liquid glass and foaming agent are gradually fed to the mixer, for example of planetary- screw type by simultaneous independent mixing of the mentioned components with ground glass to achieve the set density and homogeneousness of the batch mixture; the batch mixture, together with water, is further fed to the plate granulator; once the granules are formed, they are fed to the furnace for preliminary sintering; the proportions of components in the batch weight ready for preliminary sintering are as follows (weight percent): liquid glass and water - 5-15 % each; foaming agent - 1-2 ; ground glass - the rest.

7. Method according to claim 6, characterized in that the batch production stage that features sorting of granules prior to preliminary sintering by size, and adding kaolin or kaolinite powder 1-3 % by weight into the batch to powder the surface of granules.

8. Method according to claim 6, characterized in that during the production of batch the test measurement of proportions of components in the case of maximum and minimum allowed density of ground glass with reference to liquid glass density and the density of the batch mixture after mixing and adding minimum part of water necessary to form wet granules; the proportion is considered to be prescribed and the size of granules and quantity of batch are further adjusted by adding more water within the set limits and controlling the density of the batch during its production.

9. Method according to claim 6, characterized in that during the production of batch the proportion of glycerin in the foaming agent increasing in the case of decreased density of the ground glass; the proportion of glycerin decreasing in the case of increased average density.