RU2542027C1 - Charge for obtaining foam glass - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: charge for obtaining foam glass is made from finely crushed silicate glass of the following composition, wt %: SiO₂ - 60-72.5; CaO - 4.5-7.0; MgO - 1.5-3.5; Al₂O₃ - 1.0-2.5; Na₂O - 12.5-16.5. Glass is made on the base of trotyl and nitrobenzene production. Dolomite in an amount of 1.5-2.2% of the total charge weight is added to glass.

EFFECT: extension of the raw material base and improvement of the environment ecology.

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Description

The invention relates to the field of building materials, in particular to a technology for producing foam glass designed for thermal insulation of building structures of buildings and structures, as well as sound-absorbing, architectural and structural building material.

At present, foam glass is widely used in construction as structural and finishing materials. This material is made in the form of blocks, tiles and in the form of granules. Foam glass is a lightweight porous glass material with uniformly distributed cells (pores) with a diameter of 0.1-6 mm separated by thin walls (Glass technology. L.M. Butt, V.V. Pollyak. M .: Gosstroyizdat, 1960. C .304). The cellular structure of the foam glass can be obtained:

a) the introduction into the composition of the glass mixture of substances that cause abundant foaming in the process of glass melting;

b) the penetration of the glass melt by air or other gases;

c) foaming softened glass under vacuum;

d) foaming the ground glass with foaming agents, for example, soap root, in the cold, followed by fixing the structure by sintering the glass particles (cold method);

e) sintering a mixture of powdered glass with a blowing agent (powder method) (Glass. Handbook. A. A. Appen, M. Aslanova, N. P. Amosov, M. V. Artamonova and others. Edited by N. M. Pavlushkina. M., Stroyizdat, 1973, 487 p. (P. 164)

In industry, for the manufacture of foam-glass plates and blocks, the powder method is mainly used, which consists in sintering a mixture of finely ground glass powder with a blowing agent. Carbon substances (coke, coke, soot), various carbonates (limestone, marble, dolomite), pyrolusite and many others (Glass technology. L.M. Butt, V.V. Pollyak. M. Gosstroyizdat, 1960. S.304).

Block foam glass has a number of qualities that make it useful for both ultra-low temperature insulation (minus 180 ° C) and ultra-high (plus 400 ° C). Moisture permeability and vapor permeability of foam glass are equal to zero. Foam glass is heat-resistant, has high strength at low density. Unlike cellular gas-filled polymer materials, foam glass is resistant to chemically and biologically active environments, as well as to thermal effects. The quality and properties of block foam glass depend on its density, pore size and distribution, pore wall thickness, volumetric water absorption, etc.

The disadvantages of foam glass include the high costs of equipment, raw materials and technological energy.

There are various known blends, mixtures, compositions, ingredients that are used to obtain the final product - foam glass. The use of certain compositions for the production of foam glass may be due to a number of features of local conditions and tasks, for example, the presence of a specific raw material base, environmental problems, the composition and nature of the utilized garbage and waste, the cost of energy, the need and economic feasibility of using foam glass, for a specific purpose and given characteristics. The consequence of this diversity is the creation of a large number of compositions and technologies that take into account the specific features of such production.

So, for example, silicate glass fight is used as the basis of the most common initial blends (Schill F. Foam glass. - M .: Publishing House of Construction Literature, 1965, p.15-19; RF patent No. 2307097, С03С 11/00, application No. 2005131266, published on 09.27.2007, bull. No. 27). Advantages of such blends: cheap feedstock; disadvantages: the difficulty of collecting and preparing cullet, the low quality of the foam glass due to the inconstancy of the composition of the glass of cullet, which does not guarantee the stability of the quality of the foam glass in mechanical and automated production. The closest (prototype) is a mixture for foam glass containing 98.5-98.7 mass. % finely ground to a specific surface of 4000-4200 cm ² / g glass composition, mass. %: SiO ₂ - 70.6; CaO - 6.0; MgO - 2.7; Al ₂ O ₃ - 5.0; Na ₂ O - 13.8; Fe ₂ O ₃ - 0.72; K ₂ O - 1.9; SO ₃ - 0.3 and 1.5-1.7 mass. % of the blowing agent is anthracite (Demidovich BK Foam glass. Minsk, "Science and Technology", 1975, p.6-9). Advantages of using such a charge: high quality foam glass, due to the constancy of the composition of the glass; disadvantages: high cost of finished products.

The technical result, the solution of which the invention is directed, is to utilize the joint waste of the production of energy-saturated materials - TNT and nitrobenzene and to reduce the cost of foam glass production while maintaining its quality.

The technical result is achieved by the fact that in the charge to obtain foam glass, including finely ground to a specific surface of 4000-4200 cm ² / g silicate glass and a blowing agent, glass of composition, mass, is used as silicate glass. %: SiO ₂ - 60-72.5; CaO - 4.5-7.0; MgO - 1.5-3.5; Al ₂ O ₃ - 1.0-2.5; Na ₂ O - 12.5-16.5, made from the joint waste from the production of TNT and nitrobenzene, and dolomite in the amount of 1.5-2.2% of the total mass of the charge is used as a blowing agent.

The production of energy-saturated compounds, such as TNT and nitrobenzene, is accompanied by the formation of a significant amount of waste. So, for example, in the purification of raw trotyl, tens of thousands of tons of sulfite liquor are formed - the mother liquor for the production of trotyl containing sodium salts of asymmetric TNT isomers, nitrophenols, nitroacids, nitrite and sodium nitrate, soda, sodium sulfate and sodium sulfite, sulfide and sodium chloride (E .U. Orlova. Chemistry and technology of high explosives. Chemistry, 1973. - 688 p.). Often the production of TNT and nitrobenzene are located on the territory of one enterprise. After receiving nitrobenzene, it is separated from the nitrating mixture of acids (nitric and sulfuric), and then washing with ammonia water. The nitrobenzene production mother liquor contains about 8-10% of organic (nitro derivatives of benzene) and inorganic compounds dissolved in water, the main of which is ammonium sulfate.

According to current regulations, the neutralization of the toxic mother liquor of nitrobenzene production is allowed to be carried out together with sulfite liquors of TNT production. For this, the mother liquor of nitrobenzene is drained into the storage with the mother liquor (sulfite liquor) of TNT. According to the technology currently adopted, the mixture of mother liquors of trotyl and nitrobenzene after preliminary evaporation to a 30-40% concentration by solid residue is sent to incineration, and the resulting ash is dumped. Under the influence of precipitation, it turns into toxic effluents that pollute groundwater, which leads to a significant deterioration of the ecological situation.

Recycling of waste large-scale chemical plants through their use in the manufacture of glass can improve the environmental situation in the areas of TNT and nitrobenzene production and significantly reduce the cost of foam glass production while maintaining its quality.

The manufacturing process of silicate glass, and foam glass based on it, is as follows.

Waste from the production of energy-intensive compounds - a mixture of mother liquors from the production of TNT and nitrobenzene after chemical analysis is mixed with the required amount of silica. The introduction of water with the mother liquor solution into the mixture facilitates its hydration, which, along with the presence of weak alkalis in the solution, leads to the formation of a uniformly distributed film of alkaline compounds on the surface of quartz sand particles, and this, in turn, favorably affects the processes of silicate formation. In addition, the moistening of raw materials also has a beneficial effect on the homogeneity of the charge (Chemical technology of glass and glass. Artamonova M.V., Aslanova M.S., Buzhinsky I.M. et al. Edited by N.M. Pavlushkin - M., Stroyizdat, 1983, p. 65). The temperature of the mother liquor should be 50-60 ° C. The silica prepared in this way is mixed with the other ground components of the charge, one of which is a solid joint waste from the production of TNT and nitrobenzene - a cinder of mother liquors of energy-intensive compounds. It is worth noting that, thanks to the existing technology for neutralizing the mixture of mother liquors for the production of TNT and nitrobenzene by burning, the cinder that forms is a finely divided homogeneous composition that does not require long additional grinding. A typical chemical composition of a calcine mixture of mother liquors of trotyl and nitrobenzene is given in table 1.

Table 1 The chemical composition of cinder mother liquors of TNT and nitrobenzene Component The content of components,% Sodium sulfate 55.5 Sodium carbonate 24.6 Ammonium sulfate 9,4 Sodium chloride 8.0 Iron Oxide (Fe ₂ O ₃ ) 1,1 Carbon 1.3 Moisture 0.1 Quality response to TNT positive

The resulting mixture is loaded into crucibles, which are fed into the furnace at a temperature of 900-1100 ° C. Glass is melted at a temperature of 1300-1350 ° C. Due to the presence of sodium, magnesium, and ammonium sulfate carbonates in the charge, chemical processes in the charge begin at relatively low temperatures (330-350 ° C).

At 780-880 ° C, the liquid phase appears due to eutectics of magnesium and sodium silicates with silica and double carbonic salts with Na ₂ CO ₃ (Chemical technology of glass and glass metals. Artamonova MV, Aslanova MS, Buzhinsky I. M. et al. Edited by N.M. Pavlushkin, - M, Stroyizdat, 1983, p. 107). However, the presence of various salts of sodium and ammonium (cooking accelerators) in the waste composition leads to the appearance of fusible compounds, the melts of which are formed earlier (Glass technology. Butt L.M., Polyak V.V. - M., State Publishing House of Literature on construction, architecture and construction, 1960. S.132-133).

Carbon (in the form of soot), which is present in the cinder (from 1.1 to 5%), as well as organic reducing agents introduced into the charge as part of the mother liquor of energy-intensive compounds and gaseous products of its decomposition, directly participate in the reactions of sodium sulfate reduction. H ₂ , CH ₄ , etc., which create a reducing atmosphere in the charge. In the case of a low soot content in the cinder, a carbon-containing material in the form of coal or sawdust is additionally introduced into the charge.

The recovery of sodium sulfate begins at 740-800 ° C according to the reaction

Na ₂ SO ₄ + 2C = Na ₂ S + 2CO ₂

It is worth noting that the water present in the cinder and the mother liquor accelerates the formation of silicates. This is due to the formation of caustic soda, which interacts with silica more energetically than soda

Na ₂ S + 2H ₂ O = 2NaOH + H ₂ S;

2NaOH + SiO ₂ = 2Na ₂ SiO ₃ + H ₂ O

Silicate formation starts at 865 ° C

Na ₂ SO ₄ + Na ₂ S + ₂ SiO ₂ = ₂ Na ₂ SiO ₃ + SO ₂ + S

CaO + SiO ₂ = CaSiO ₃

Homogenization requires an increase in the temperature of the glass melt to 1300-1350 ° C. The presence of sodium sulfate, sodium chloride and ammonium sulfate (up to 3%) in the mixture helps to accelerate the process of manufacturing glass melt, its clarification and homogenization (Handbook for the production of glass. Edited by II Kitaigorodsky. AI Berezhnoy, Yu.A. Brodsky, Z.I. Bronstein and others; Edited by N.M. Pavlushkin, M., State Publishing House of Literature on Construction, Architecture and Construction, 1963. P.160-162).

To assess the quality of the glass melt obtained on the basis of the joint waste of energy-intensive compounds, laboratory experimental melts of glass blends were performed: the maximum temperature for heating the glass melt was 1300-1350 ° C, and the exposure time of the molten glass at the maximum heating temperature was 35-60 min. Glass blends were designed to obtain silicate glass composition: wt.%: SiO ₂ 72,0; Al ₂ O ₃ 1.5; CaO 7.0; Na ₂ O 16.5; MgO 3.0. For comparison, glass melt samples of the same composition were made from carbonate blends prepared using traditional raw materials.

Table 2 shows the composition of glass blends to obtain alumina-magnesia glass composition, mass. %: SiO ₂ - 72.0; CaO - 7.0; MgO - 3.0; Al ₂ O ₃ - 1.5; Na ₂ O - 16.5 and its characteristics.

table 2 Quality of glasses made on the basis of joint waste from the production of TNT and nitrobenzene and according to traditional technology Charge Glass Technology The composition of the charge,% Firing temperature / holding, ° С / min Specific
density,
g / cm ³ Solubility in water,% Color uniformity Based
a joint
departure
productions
TNT
and nitrobenzene Sand 43.83
Ash 29.22
Chalk 1.08
Dolomite 10.36
Clay 2.41
Coal 1.84
A mixture of mother liquors 9.3
(solid) 1350-1400 / 35-45 2.54-2.55 1.16-1.18 Light blue
homogeneous
cracks Based
traditional
materials Sand 59.30 Soda 21.95 Chalk 1.46 Dolomite 14.00
Clay 3.26 1350-1400 / 35 2.35-2.50 1,5-2,2 Light green, uniform, bubbles and cracks

As can be seen from the tabular data, the total content of the combined waste of the TNT and nitrobenzene production in the charge used to produce glass according to this invention is more than 35%, which significantly reduces the cost of the charge for glass production and allows you to completely utilize the current waste from the production of TNT and nitrobenzene.

The method for producing foam glass is as follows: samples of silicate glasses are crushed to particles with a diameter of 0.2 mm or less. As a blowing agent, dolomite is used in an amount of 2% of the total mass of the charge, which is also crushed to a powder size of 0.2 mm or less. The components thus prepared, after weighing, are thoroughly mixed and then subjected to co-grinding to a specific surface of 4000-4200 cm ² / g. The resulting mixture is loaded into a disassembled steel mold. A thin layer (1.5-2 mm) of Mertel paste-like refractory mastic based on refractory powder and kaolin clay is carefully applied to the inner surface of the steel mold. After coating the form with mastic, it is dried in an oven at a temperature of 350 ° C for 15 minutes.

A tightly closed mold with a charge is placed in an oven at a temperature of 450 ° C. Within 15 minutes, the furnace is heated to 800 ° C, after which the heating is stopped, and the furnace is rapidly cooled to a temperature of 500-600 ° C, thereby freezing the cellular structure of the foam glass. The following is annealing of the foam glass and cooling.

Samples of foam glass based on glasses made from the joint waste of the production of TNT and nitrobenzene and traditional materials were obtained. The quality of the foam glass samples is shown in table 3.

Table 3 The quality of the foam glass samples Technology Tempera-
firing round / aging, ° С / min Tensile strength
under compression, MPa (kg / cm ² ) Specific
density, g / cm ³ Water absorption,% Structure From glass
based on joint
waste 800/10
800/10 5.90 (59.0)
8.30 (83.0) 0.25
0.33 15.0
8.0 Medium
pores From glass
based on traditional
raw materials 800/10
800/10 4.27 (42.7)
4.75 (47.5) 0.39
0.40 13.0
18.0 Large
pores

As can be seen from the results obtained, the quality of the foam glass samples obtained from the joint waste of the production of TNT and nitrobenzene and traditional materials is almost the same. Characteristics of foam glass samples obtained on the basis of experimental and traditional blends correspond to the main indicators of industrial samples of foam glass manufactured, for example, for heat-insulating structural blocks (Products and materials from foam glass. Technical specifications TU 5914-001-73893595-2005. Developed by ZAO “ Perm production of foam silicates ”).

Thus, the production of samples of foam glass based on silicate glass, made from the joint waste from the production of TNT and nitrobenzene, leads to the cheapening of foam glass without reducing its quality.

Claims (1)

The mixture for producing foam glass, including finely ground to a specific surface of 4000-4200 cm ² / g silicate glass and a blowing agent, characterized in that glass composition is used as silicate glass, wt.%: SiO ₂ - 60-72.5; CaO - 4.5-7.0; MgO - 1.5-3.5; Al ₂ O ₃ - 1.0-2.5; Na ₂ O - 12.5-16.5, made from the joint waste of the production of TNT and nitrobenzene, and dolomite in the amount of 1.5-2.2% of the total mass of the charge is used as a blowing agent.