RU2045495C1 - Raw material mixture for manufacture of building products - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: raw material mixture for manufacture of building products contains component from group including tripolite, diatomite, opoka 75-99% and alkali effluent (in terms of dry matter) of caprolactam production 1-25% Mixture characteristics: firing temperature 80-1100 C; compression strength 55.4-91.7 MPa; bending strength 30.1-56.8 MPa; density 1020-1460 kg/cu.m. EFFECT: higher efficiency. 3 tbl

Description

 The invention relates to the building materials industry and can be used for the production of ceramic bricks, stones, blocks and tiles.

Known raw mix for the manufacture of wall ceramic products, including the following components, wt. clay shales from overburden of phosphorites 74-85; clay 10-25 and sulphate mixture waste caprolactam production 1-5 [1]
When brick is fired, sulfur dioxide, chlorine and the corresponding acid fumes are formed from this raw material mixture resulting from chemical reactions of Na ₂ SO ₄ and NaCl contained in the sulfate mixture with its other components. All these substances have a harmful effect on the human body, cause corrosion of technological equipment, do not allow to utilize the heat of exhaust gases, for example, for drying raw brick, and pollute the environment. Non-decomposed, as well as secondary sodium sulfate formed during firing, is a water-soluble salt that forms efflorescences on the surface of the brick, reducing its durability and decorative properties. Sulfate and sodium carbonate, sulphate contained in the mixture decompose at temperatures above 850 ^C. The resulting decomposition of reactive sodium oxide participating in the formation of neoplasms, interacts with the components of the clay (SiO _2, Al ₂ O _3, FeO, etc. .) only after amorphization m. e. at a temperature above 900 ° ^C. Because of this brick firing temperature of 1000-1050 ^o C.

In addition, brick from known raw mixture has a higher density and lower strength due to the presence of an inert (non-reactive) having a stable crystal lattice of silicon oxide (β-quartz) interacting with other oxide-mixture at a temperature above 1050 ^{° C,} and at temperature of 1000-1050 ^{° C} it is advantageously in the form of inclusions of inert and does not participate in the formation of a durable ceramic crock.

Known raw mix for the manufacture of ceramic products containing active silica 72.4-74.7% ash TPP 7.7-11.0% alkaline soap waste chemical industries 15.3-17.6% [2]
This mixture has significant disadvantages. The presence of sulfur compounds in the ash composition, and in most soap production waste, for example, soap liquors up to 10% NaCl, causes the negative effects described above. The components included in the composition of alkaline soap waste do not provide the formation of polymerized particles of colloidal composition of micelles, which contribute to the convergence of solid rock particles at the drying stage, increasing their surface of the reaction interaction during the firing process. This factor, as well as the low content of active NaOH in the waste (0.1%), which promotes the formation of a liquid phase, predetermines the occurrence of mainly solid-phase reactions during firing, which ultimately explains the relatively low compressive strength (268-305 kg / cm ² ) calcined at a temperature below 1100 ^about With products from this mixture. The need to conduct the firing at a temperature above 1100 ^{° C} requires higher fuel costs and costs for refractory materials for the production and frequent furnace repair and trolleys.

 The three-component composition of the mixture, in comparison with the two-component, significantly complicates the production line and increases the cost of production.

Known raw mix for the manufacture of small piece building products, including, by weight. diatom material 64-70; limestone 10-16; soap liquor 16-25 [3]
The disadvantages of this raw material mixture are: increased costs for equipment and energy costs associated with the need for fine grinding of diatom material and limestone (before passing through a 1 mm sieve) and the complication of obtaining a homogeneous mixture of three components (the need to pass the mixture through a 1.5 mm sieve); High-temperature firing products (1100 ° ^C) and their relatively low compression strength (412-466 kg / cm ²⁾ due to loosening semifinished structure emits carbon dioxide and the reaction proceeds in the solid phase; the formation of “dutiks” and spalling in products from the contact of active CaO larger than 0.5 mm with atmospheric moisture (since limestone is milled to 1 mm, naturally there are particles in the mixture over 0.5 mm that pass into the product when fired) ; the release of chlorine during the firing of products, the harmful effect of which has already been noted above.

Closest to the recommended is a raw material mixture for the manufacture of building products, including, by weight. component from the group: tripoli, diatomite, flask 66-72; calcium chloride production waste 6-12; soap liquor 20-24 [4]
The high content of chlorides and sulfates that make up soapstone liquor and waste from the production of calcium chloride has a harmful effect on humans, equipment and product quality, as noted above. The release of a significant amount of gases (SO ₂ , Cl, CO ₂ , hydrocarbons) during firing products leads to the destruction of the integrity of the product, the displacement of the sintering process in the temperature zone above 1000 (1120 ^about C) and a decrease in strength. The content of sulfates in the mixture does not allow to obtain facial ceramic products from it due to fading and punctures on their surface. In addition, the increased content of carbonates and sulfates in the mixture causes the formation of gelenite and anhydride in the products, which also reduce the strength of the products. The low (0.1%) content of free alkali in the soap base liquor, the high content of calcium oxide in the mixture and the release of a large amount of gases from the products during firing predetermine the occurrence of mainly reactions in the solid phase. Sintering of the material occurs at high temperature, which requires high fuel consumption and increases the cost of refractory materials for furnaces and trolleys. The strength of the products from the mixtures indicated in the prototype is also not very high for compression of 498-510 kg / cm ² and bending of 15.9-29.6 kg / cm ² .

 The aim of the invention is to reduce the firing temperature of ceramic wall products, increase their strength characteristics, utilize chemical production wastes, and eliminate harmful emissions into the atmosphere.

 The problem is achieved in that the raw material mixture for the manufacture of building bricks, including silica-containing raw materials and caprolactam production waste, contains silica-containing raw materials (silica, diatomite, tripoli) as alkali-containing raw materials, and caprolactam production alkaline waste as the alkaline waste ratio of components: wt.

Amorphous siliceous
breed (diatomite, flask, tripoli) 75-99
Alkaline effluents
caprolactam
(in terms of dry matter) 1-25
The use of amorphous-siliceous rocks in an amount of 75-99 wt. together with the alkaline runoff of caprolactam production (ShchSPK) in the amount of 1-25 wt. provides a dense and durable structure of raw brick as a result of the interaction of amorphous silica, which is part of amorphous-siliceous rock, with the sodium salts of mono-dicarboxylic acids SHCHSPK still in the process of drying the brick (100 ^about C) and the formation of polymerized particles of colloidal silica micelles, enveloping solid particles contained in the rock, bringing them closer and increasing the surface of the reaction interaction in the firing process. The increased density of the raw brick contributes to the prolongation of the process of burning up of organic substances ShchSPK and its completion in the field of elevated temperatures. During combustion, organic substances create a reducing environment and pore material (product). Active NaOH, which is 20 times greater in alkali-silicate complex (2.0% versus 0.1%) than in soapstone, and Na ₂ O is the thermal dissociation product of mono- and dicarboxylic acids of alkali green alkali sulfate, interacts with amorphous silica to form alkaline silicates: 2Na ₂ O ˙ SiO ₂ ˙ Na ₂ ˙ SiO ₂ and Na ₂ O ˙ 2SiO ₂ . Reducing environment and the proximity of particles of amorphous silica, due to the formation of micelles as well as the presence in the mixture of the other oxides (FeO, Al ₂ O ₃₎ promotes the formation of highly silicate and sodium melt at a temperature of about 600 ^{° C,} which reacts with the solid phase, activating process sintering particles. As a result of crystallization of the melt, strong minerals are formed (albite, oligoclase, sodium ferrosilicate), which determine the high strength properties of the products. When the content of the mixture is less than 1% SCHSPK melt formation is shifted to higher temperatures (> 800 ^C). When the content of alkali metal oxide in the mixture exceeds 25%, an excessive amount of a highly mobile (with low viscosity) melt enriched with Na ₂ O is formed, which actively reacts with crystalline silicates and destroys the structural framework of the ceramic crock, reducing its strength.

 Thus, the use of the proposed mixture allows to obtain high-strength products with low density at low firing temperatures, and the absence of harmful substances in the components of the mixture makes the process of obtaining products from the proposed mixture environmentally safe and eliminates equipment corrosion.

 For the manufacture of products, the Kamyshlov diatomite, Balashayka flask, Tripoli and ShchSPK containing sodium salts of organic acids 26.48 were used as raw components of the mixture; resins 6.80; cyclohexanol 0.009; cyclohexanone 0.008; sodium hydroxide 2.0, water 64.703.

The chemical compositions of diatomite, flask and tripoli are given in table. 1. The manufacture of samples is as follows. Amorphous siliceous rocks (diatomite, flask, tripoli) was ground to pass through a sieve of 3 mm, and then mixed with SCHSPK which can be used in liquid form, as a paste or dry form, after dehydration at ¹⁰⁰ ° C, and and after a preliminary calcination at 200-700 ^C. The dried SCHSPK also milled to a particle size less than 3 mm. After mixing the components, the mixture was moistened to 15% humidity and formed by semi-dry pressing at a pressure of 130 kg / cm ² sample cylinders with a diameter and height of 50 mm and plates 150 x 20 x 10 mm. Molding can also be carried out in a plastic way, in which case the molding moisture will be 30%
Samples were dried at ¹⁰⁰ ° C for 2 hours and then calcined at 680-1000 ^{° C} (depending on the content of the mixture SCHSPK) and held at maximum temperature for 30 minutes. The rate of rise of the firing temperature to the maximum was 10 deg / min. The samples were cooled for 2-3 hours. Depending on the ratio of the components in the mixture and the firing temperature, the samples have a color from milky white to bright red.

 The compositions of the raw mix are given in table. 2, and the indicators of the obtained samples in table. 3.

 The highest firing temperature indicated in the table. 3 is the maximum for each composition. With an increase in the firing temperature above the maximum, deformation or swelling of the samples is observed, and at a temperature below the minimum, their qualitative indicators sharply fall.

Thus, the advantages of the proposed mixture before mixtures given in the prior art (NN 10, 11, 12) and in the analogues are: temperature calcination products of the proposed mixture to ^about 300-400 C below, that ensures a significant reduction of energy consumption for production, the increase in life the service of furnaces and trolleys, as well as the reduction in the cost of materials for their manufacture, since the need for refractories is reduced: at a lower density, and therefore mass, the strength of products from the proposed mixture is higher than that of products from mixtures specified in prototype and analogues; when firing products, no harmful substances are released.

Claims (1)

 RAW MATERIAL MIXTURE FOR PRODUCTION OF CONSTRUCTION PRODUCTS, including a component from the Tripoli group, diatomite, flask and alkaline production waste, characterized in that it contains alkaline stock production of caprolaclam in the following ratio of components, wt. Component from the Tripoli group, diatomite, flask 75 99
Caprolactam production alkaline stock (dry) 1 25

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