SU1757456A3 - Method of making construction products - Google Patents

Abstract

SUMMARY OF THE INVENTION The TPP ash is mixed with a binder based on a water soluble sodium salt, injected in an amount of 5.5-14 wt.% Based on the mass of dry ash, molded and immediately calcined when exposed to a temperature of 250-900 ° C for a time determined by the formula t 1: (at + b), where t is the firing time, h; t is the burning temperature, &C: a is a coefficient equal to 10 b is a coefficient equal to 0.25 h. 2 tabl., 1 sludge.

Description

The invention relates to the building materials industry and can be used for the production of bricks, stone blocks, tiles, tiles for housing, civil and industrial construction.

There is a known method of making wall ceramics, according to which the fly ash is pre-ground to full passage through a sieve of 900 holes / cm; then mixed with the secondary cement dust in the ratio of components, wt.%: fly ash 55-85; secondary cement dust 15-45. The mixture is mixed with water to a moisture content of 21-23%. The products are molded by pressing, after which they are dried, raising the temperature from 30-35 ° C to 100-120 ° C for 15-20 hours. The products are fired at 1080 ° C and held for 2 hours.

The disadvantages of the method are low efficiency of utilization of fly ash, high firing temperature and low compressive strength of products.

There is a method in which the ash TPP is mixed with fuel slag and liquid glass in the following ratio,%: fly ash (fine fraction) 72-77; fuel slag 20-25; liquid glass 3. The resulting mixture is molded by pressing under a pressure of 21-35 MPa and dried for 5 hours at 160 ° C. Then the temperature is raised to 53b ° C for 4 hours, held for 2 to 6 hours and the temperature is raised to 1080 ° C with a speed 35-79 ° C / h Total firing cycle time 24-30 h.

The method is characterized by a long duration, high firing temperature and a large bulk density of the obtained products.

A known method of manufacturing wall products in which the TPP ash is preliminarily calcined at 800-820 ° C for 2-2.5 hours, then mixed with diluvial clay in a ratio,%: ash 70-75; clay 25-30. The resulting mixture is molded into bricks, dried and baked according to the mode: temperature rise to 250 ° С at a rate of 4 deg / min; from 250 ° C to 600 ° C at a rate of 10 deg / min; from 600 to 800 ° C - 4 degrees / min; from 800 to 1150 ° С - 10 degrees / min; holding at 1150 ° C 30 min.

The disadvantages of the method are the complexity of the heat treatment, the high firing temperature, and the low compressive strength of the resulting products.

In order to increase the strength and increase the time of setting, it is proposed to shut the solution with an alkaline solution.

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shutting solution with alkaline component. The pre-blast granulated slag is ground together with Portland cement clinker to a grinding fineness of at least 3000 cm2 / g, then the resulting shutter is closed with a solution of the alkaline component (soda, potash, caustic alkali, soluble silicates with a silicate module from 0.5 to 2.5) At the same time, the ratio of components is maintained within the following limits, in May,% granulated blast furnace slag, an alkali metal compound in terms of sodium oxide h3 -12; Portland cement clinker 1-9.

The method of obtaining a binder does not allow the use of ash from thermal power plants, requires long-term milling and, consequently, is accompanied by large energy consumption.

There is a known method for the manufacture of building products, according to which the ashes of thermal power plants, bo powder of glass, granulated phosphorus slag are sieved, each component separately, through a 0.08 sieve. Then, 3-7 wt.% Ash of thermal power plants are weighed, 7-15 May% bo powder of glass, 67-70 may% granulated phosphorus slag thoroughly mix the dry ingredients together, add 10-11 may. alkaline solution and stirred until a homogeneous wet mass is obtained. The resulting mass is molded into articles by pressing at a pressure of 5-10 MPa. The products are dried at 60-100 ° C for 2 hours and calcined at 9QO-950dC for 1-3 hours.

The disadvantages of the method are low utilization efficiency of TPP ash because of its low content in the composition, high energy consumption associated with the need to obtain a bog glass powder, screening and multiple mixing of components, drying products and a high firing temperature, a large volume mass of products.

The closest to the technical essence is the production construction goods, in which the dry ash with the addition of 10-15% clay and coal waste is moistened with a 3% solution of liquid glass and orthophosphoric acid of extraction production to a moisture content of 13-16% by weight of dry powder After thorough mixing, the products are formed by semi-dry pressing, placed in an oven, the temperature is raised at a rate of 1.5-2.0 degrees / minute until the ash begins to soften or 20-30 ° higher and maintained at this temperature for 1 hour.

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The method has the following disadvantages: low efficiency of using ash, as the mixture contains additional ingredients in the amount of 26-3%, high energy costs due to the long time of rise of the firing temperature (from 12 to 17.5 hours); a large volume mass of products due to the high firing temperature of products.

The aim of the invention is to increase the efficiency of disposal of ash, reducing energy consumption and bulk density of products.

This goal is achieved by the fact that in the method of manufacturing building products, including mixing TPP ash with a binder based on a water-soluble sodium salt, molding and roasting, the binder is used in an amount of 5.5-14% by weight based on the mass of dry ash sodium oxide, and roasting is carried out immediately after molding when exposed to a temperature of 250-900 ° C for a time determined by the formula

aiTb

where t is the firing time, h;

t is the burning temperature, ° С;

a - coefficient equal to h 1grad

b - coefficient equal to 0.25 hours

The proposed method has the following technical advantages: using only one ash of a thermal power plant as a charge dramatically increases the efficiency of using ash; the content of water-soluble sodium salt in the range of 5.5-14 wt.% from the mass of dry ash in terms of sodium oxide provides the ultimate strength of products under compression from 42 to 62 MPa (prototype 14-23), volume 17 g / cm (prototype frost resistance of more than 50 cycles (prototype 24-60 cycles).

When the content of the compound is sodium less than 45 wt.% Of the mass of dry ash, a significant decrease in the strength of the products is observed.

When the content of the sodium compound is more than 14 wt.% Based on the mass of dry ash, a further increase in the strength of the products under compression is not observed, the bulk density does not decrease, and the leaching of the sodium compound begins upon exposure to water.

When baking wet products after molding, products with a uniform matte surface and regular strength are obtained. When exposed to air, i.e. during natural drying, a coat of alkali metal carbonate appears on the surface of products, after firing, the surface

weight from 1.21 to 1.1 1.32-1.72 g / cm3), MOf

50

55

products are devoid of noble texture, durability of products becomes irregular in thickness. Calcination of wet products immediately after molding makes it possible to reduce energy costs and increase the productivity of the method by eliminating the operation of drying products. At the same time, this provides for obtaining products with a lower bulk density without introducing additional substances and operations.

Firing products at temperatures below 250 ° C makes it possible to exceed the compressive strength of the products and somewhat reduce the bulk density of the products relative to the prototype, however, this results in low frost resistance of the products. Heat treatment of products at temperatures above 250 ° C allows to obtain high frost resistance while simultaneously improving other characteristics of the products (increasing strength and reducing bulk density). Obtaining higher technical characteristics of products in a lower temperature range (250 ° C and higher) as compared with the prototype (900-950 ° C) is a new super-effect, since according to classical ideas, an increase in the technical characteristics of ceramic products can be achieved even more. an increase in firing temperature. However, lowering the firing temperature reduces energy consumption and the bulk density of products.

Determination of the firing time depending on the firing temperature according to the equation t 1 / (at + b) allows you to set the optimal technological mode of the process in a wide temperature range (250 ° C and higher), which reduces energy consumption and provides a more flexible technology for producing products with adjustable properties compared to the prototype.

Example 1. A solution of caustic soda in an amount (wt.% In terms of sodium oxide) is added to the ash of TES-1: 4.5; 5.0; 5.5; 6.5; 13; 14; 15 by weight of dry ash. Stir the mixture thoroughly until a uniform wet mass is obtained. Bricks are molded from the mixture obtained using the extrusion method. Pressing pressure 5,0-7,5 MPa. Immediately after molding, the product is subjected to heat treatment at a temperature of 250 ° C for 2 hours. The obtained products are tested according to GOST 530-80, GOST 8462-85, GOST 7025-78.

Example 2. A solution of caustic soda in an amount (wt.% In terms of sodium oxide) is added to the ash of TES-2: 4.5;

5.0; 5.5; 6.5: 13: 14; 15 by weight of dry ash. Stir the mixture thoroughly until a homogeneous wet mass is obtained. Bricks are molded from the completed mixture by pressing. Pressing pressure 5,0-7,5 MPa. Immediately after molding, the product is subjected to heat treatment at a temperature of 250 ° C for 2 hours. The resulting products are tested according to GOST 530-80; GOST 8462-85, GOST 7025-78.

Example 3. A solution of caustic soda in the amount of 5.5 is added to the ash of TES-1.

5% by weight of dry ash and mix thoroughly until a uniform wet mass is obtained. the resulting mixture is molded bricks under a pressing pressure of 5.0-7.5 MPa. Immediately after forming the product, separate batches are subjected to heat treatment at temperatures of 100, 200, 250, 300, 500, 750, 900 ° C for 2.9; 2.2; 2.0; 1.8; 1.3; 1.0; 0.7 hours, respectively.

5 Example 4. A solution of soda ash in the amount of 5.5 wt.% Based on the mass of dry ash is added to the ash of TES-1 and the mixture is thoroughly mixed until a homogeneous wet mass is obtained. From received

Mixtures molded bricks at a pressing pressure of 5.0-7.5 MPa. Immediately after molding, the product is subjected to heat treatment at a temperature of 900 ° C for 0.7 hour. Example 5.

5 solution of bicarbonate soda in the amount of 5.5 may% by weight of dry ash and mix the mixture thoroughly until a homogeneous wet mass is obtained. The resulting mixture is molded bricks at a pressure

0 pressing 5.0-7.5 MPa. Immediately after molding, the product is subjected to heat treatment at a temperature of 900 ° C for 0.7 hour.

Example 6. TES-1 ash is added

5 A solution of caustic soda in an amount of 5.5% by weight based on the mass of dry ash and thoroughly mixed until a homogeneous wet mass is obtained. Bricks are molded from the resulting mixture at a pressing pressure.

0 5.0-7.5 MPa. Immediately after molding, the product is heat treated under the following conditions:

t 250 ° C; t 1 h; 2 h; 3 hours; Estimated time 2 hours;

5-1,500 ° C; g 1 h; 2 h; 3 hours; Estimated time 1.3 hours;

t 900 ° C; t 1 h; 2 h; 3 hours; estimated time of 0.7 h.

The results are summarized in table. 2. As can be seen from the obtained data, the addition of sodium compounds to the ash of TPPs

less than 5.5 wt.% leads to a decrease in the strength and frost resistance of the obtained products. Adding a compound higher than 14 May% is not economically feasible. In addition, this leads to leaching of the alkali metal compound in water. In the range of 5.5-14 wt.%, An increase in the strength and a decrease in the bulk mass of the products relative to the prototype is achieved.

Variations in the quantitative ratio of the ash components (TPP-1 and TPP-2) do not have a noticeable effect on the final result.

Adding sodium compound to the solution of mixing in the range of 5.5-14 wt.% In terms of Na20 leads to a decrease in the lower limit of the firing temperature range to 250 ° C, which ensures a reduction in energy costs for the production of building products while improving their performance

At the same time, the claimed method, in comparison with the prototype, increases the efficiency of ash utilization to 86-94.5 wt.%.

The drawing shows the experimental dependence of the calcination time of the products on the calcination temperature for various sodium compounds (caustic soda, bicarbonate soda, calcinated soda).

Dots marked with an asterisk refer to caustic soda formulations; the points indicated by the circle refer to formulations with bicarbonate soda; the points indicated by the box refer to soda ash formulations.

The proposed mathematical dependence of the firing time of products on the firing temperature t 1 (at + b) satisfactorily describes the process in the case of using various alkali metal compounds in the temperature range of 250-900 ° C

Comparison of the amount of time required for firing products at a given temperature, calculated by the formula and according to the prototype, shows that the calculation by the formula ensures the achievement of the required technical characteristics of products during firing for at least a long time and thus makes it possible to reduce energy costs.

Thus, the proposed method

provides a new positive effect for the national economy of the country, which consists in increasing the efficiency of ash utilization, reducing energy consumption and the bulk density of products.

Claims (1)

Invention Formula A method for manufacturing building products, which includes mixing TPP ash with a binder based on a water-soluble sodium salt, molding and roasting, and so that, in order to increase the efficiency of ash utilization, to reduce energy consumption and the bulk density of products, the binder is used in the amount of 5.5-14 wt.% from the mass of dry ash in the calculation of sodium oxide, and roasting is carried out immediately after molding when exposed to a temperature of 250-900 ° C for a time determined by the formula g 1: (at + b), where g is the firing time, h; t is temperature, ° С; a is a coefficient equal to h t deg -1, b is a coefficient equal to 0.25. Table  The content of the compound is indicated in terms of NatO; heat treatment time calculated by the formula. ABOUT 0.5 100 300500 700 900 BURNING TEMPERATURE, ° C