RU2703036C1 - Method of making heat-resistant concrete mixture and method of making articles from heat-resistant concrete mixture - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to methods of producing concrete mixture and heat-resistant concrete articles suitable for making lining of industrial heat and refractory units, in particular for lining firing bricks and other units. In the method of producing heat-resistant concrete mixture, which includes mixing chamotte filler and self-decomposing ferrochromium slag, according to the invention, chamotte filler used is chamotte flue dust in amount of – 11.1…12.2 %, self-decomposing ferrochrome slag in amount of 13.8…15.4 %, additionally, the following is added: spent aluminum alloys etching solution – 40.0…42.0 % and nickel slag in amount of 30.4…35.1 %, mixing is carried out in a reactor at pH 7.7…8.5 and T = 150…155 °C, then mixture is ground to particle size 4…7 mm in disintegrator. Besides, the technical result is achieved due to that in the method of making articles from heat-resistant concrete mixture containing self-decomposed ferrochrome slag and chamotte filler, including its hardening, according to invention, said concrete mixture is produced according to said composition, compacted on vibrating bench, and hardening is performed in hot treatment in hot air chamber at temperature 150…155 °C for 6 hours and obtain article with strength equal to and less than 85…90 MPa. Proposed method makes it possible to efficiently use production wastes that do not find wide industrial application, improve environment, obtain strong heat-resistant concrete products.

EFFECT: improvement of environment ecology due to use for production of concrete mixture of production wastes processed with low power consumption, and production of heat-resistant concrete products with high strength (at least 85…90 MPa).

2 cl, 1 dwg, 2 tbl

Description

The invention relates to methods for the production of concrete mix and heat-resistant concrete products suitable for the manufacture of lining of industrial thermal and refractory aggregates operating at temperatures up to 1300 °, in particular for the lining of brick kiln cars and other heat-insulating aggregates.

A known method of manufacturing a heat-resistant concrete mixture, including mixing chamotte aggregate, finely ground additives (chamotte and calcined hydrated alumina cement), ferrochrome slag and water glass, and a method of manufacturing products from heat-resistant concrete mixture, including hardening (SU 590291, 1976).

This method has the disadvantage that it is not economical to use for the manufacture of heat-resistant concrete mix using scarce alumina cement.

There is also a known method of manufacturing refractory materials using concrete technology for lining brick firing cars and other thermal units, comprising mixing fireclay aggregate of two fractions (less than 8 mm and less than 3 mm), self-decaying ferrochrome slag, liquid glass (density 1.39-1.41 g / cm ³ ) and foams based on synthetic foaming agent or hydrolysers in protein (RU 2145311, С 04 В, 1998).

The disadvantages of this method are the low mechanical strength of the lining elements of thermal units in the temperature range of 20-1300 ° C (up to 20 MPa), increased porosity and low heat resistance of concrete (30-40 water heat exchangers).

A known method of manufacturing a heat-resistant concrete mixture and a method of manufacturing products from heat-resistant concrete mixture (RU 2284305), which is the closest invention to the technical essence.

This method of manufacturing a heat-resistant concrete mixture involves mixing chamotte aggregate and self-decaying ferrochrome slag, moreover, chamotte fractions of 5-10 mm and less than 5 mm are used as chamotte aggregate, and after this mixing caustic soda is introduced into the resulting dry mixture in the form of an aqueous solution in the following the ratio of components, mass. %:

Chamotte fraction 5-10 mm - 30-32

Chamotte fraction less than 5 mm - 30-32

Self-decaying ferrochrome slag - 22-26 Hard caustic soda - 2-4 Water - 10-13

Then, from the resulting mixture, products are made, the mixture is compacted with vibration, and hardening is carried out during heat treatment according to the following regime:

Raising the temperature to 60-70 ° C for 2.0-2.5 hours

Exposure at 60-70 ° C for 14 hours

Raising the temperature to 90-95 ° C for 1.5-2.0 hours

Raising the temperature to 110-120 ° C for 2.0-2.5 hours

Exposure at 110-120 ° C for 10 hours

Lowering the temperature to 50-70 ° C for 3-4 hours (US Pat. RF No. 2284305, С04В 28/08, 2006).

The disadvantages of such methods are the high consumption of ground fireclay and increased energy consumption for heat treatment of the concrete mixture.

The technical task of the invention is to improve the environment due to the use for the production of concrete mixtures of production waste processed with low energy consumption and obtaining heat-resistant concrete products based on it with high strength (not less than 85 ... 90 MPa).

The technical result of the proposed method is achieved by the fact that a method of manufacturing a heat-resistant concrete mixture, comprising mixing fireclay aggregate and self-decaying ferrochrome slag, according to the invention, fireclay dust is used as fireclay aggregate in the amount of 11.1 ... 12.2%, self-decaying ferrochrome slag in the amount of 13.8 ... 15.4%, in addition, add: the spent etching solution of aluminum alloys (silumin) - 40.0 ... 42.0% and dump nickel slag in the amount of 30.4 ... 35.1%, mixing carried out in a react ore at pH = 7.7 ... 8.5 and T = 150 ... 155 ° C, then the mixture is ground to a particle size of 4 ... 7 mm in a disintegrator.

In addition, the technical result is achieved due to the fact that, the method of manufacturing products from heat-resistant concrete mixture containing self-decaying ferrochrome slag and chamotte aggregate, including its hardening, according to the invention, the manufacture of the specified concrete mixture is carried out according to the above composition, compact it, and hardening carried out during heat treatment in the chamber with hot air at a temperature of 150 ... 155 ° C for 6 hours, and get the product with a strength equal to and more than 85 ... 90 MPa.

Self-decaying slag of low-carbon ferrochrome containing, macc. %: SiО ₂ -26 ... 29; A1 ₂ O ₃ -5 ... 8; CaO-48 ... 51; MgO-12 ... 16; Cr ₂ O ₃ -3.5 ... 5.5 and FeO-1.0 ... 1.5 are produced by the Chelyabinsk Ferroalloy Plant in huge volumes, do not find wide industrial use, are partially used for the manufacture of silicate bricks, and about 50% are stored in dumps.

Sump nickel slag containing, mass. %: SiO ₂ -41.8; Al ₂ O ₂ -7.3; CaO-12.5; MgO-10.8; FeO-24.5, manufactured by the Chelyabinsk Nickel Plant, has increased activity and after the introduction of special additives it can be used to replace part of the cement in the manufacture of building materials and heat-resistant slag metal, but all these proposals have high costs and are not yet implemented.

Fireclay dust, containing, mass. %: SiO ₂ -59.1; A1 ₂ O ₃ -29.7; MgO-2.7 and Fe ₂ O ₃ -3.4, is produced in significant quantities at the Chelyabinsk Metallurgical Plant upon receipt of chamotte and is used partially in circulation, the excess is dumped into the dump (Rational use of natural resources of the Chelyabinsk region. V. Barkhatov, Dobrovolsky I.P., Kapkaev Yu.S. - Chelyabinsk: Publishing House Chelyab.gos.un-ta, 2015).

Spent etching solution of aluminum alloys (silumin), containing, mass. %: NaOH-2.9 ... 3.4; Na ₂ SiO ₃ -9.6 ... 101; NaAlO ₂ -46 ... 49; H ₂ O-39 ... 42, which is obtained in significant amounts when alkali is treated with aluminum alloy products before assembly of units (for example, motors at the Chelyabinsk Automotive Plant) and has not yet found wide industrial application.

A method of obtaining concrete mixture from the specified waste composition for the manufacture of heat-resistant concrete products based on it consists of reacting silicon oxide from chamotte ablation dust with an alkali solution and sodium aluminate from a spent solution of etching aluminum alloys (silumin) and simultaneously calcium oxide of low-carbon ferrochrome slag with active aluminum hydroxide released during this interaction with the formation of aluminosilicate binder and alumina cement.

A known method of obtaining in industrial conditions aluminosilicate binder based on liquid sodium glass and aluminum oxide by heat treatment at a temperature of 150 ° C for 6 hours. Aluminosilicate bonds are mixed with liquid glass, depending on their chemical composition and processing conditions. So, for example, a bond of the composition Na ₂ O / A1 ₂ O ₃ = 5.95 is mixed with 3-module liquid glass in all volume ratios. When the ratio of Na ₂ O / A1 ₂ About ₃ = 2.90 mixing of the ligament occurs to a ratio of 50/50. In the composition with a ratio of Na ₂ O / A1 ₂ O ₃ 10/90, the maximum proportion of Al ₂ O ₃ can be no more than 1.5%, in the composition of 20 / 80-4.5%, and in the composition of 50 / 50-6, 5%.

With this treatment, the following reaction proceeds (1):

Such a bond has high strength and heat resistance and is used for the manufacture of refractory materials (glue, putties, plates, etc.). It was also established that when the specified limits for the content of aluminum oxide are exceeded, the fluidity of the binder decreases and it thickens, and when the content of aluminum oxide in it decreases below the specified limits, the strength of concrete obtained on its basis significantly decreases, which is confirmed by the data in Table 1 [Sychev M Inorganic adhesives. -L., Chemistry, 1984, S.93.].

Considering the above and due to the fact that it is not economically profitable to use liquid glass and alumina for the manufacture of this aluminosilicate binder, it was proposed to use industrial wastes in the above ratio when processing them in a reactor equipped with a high-speed stirrer under the following conditions: pH equal to 7.5 ... 8.5, the temperature of the process is 150 ... 155 ° C, while the following reactions proceed (2-5):

After completion of the reactions (termination of steam evolution), a predetermined amount of dump nickel slag is fed into the reactor, the mixture is mixed well and then transferred to a disintegrator. In a disintegrator, the mixture is crushed to a particle size of 4 ... 7 mm, while its activity increases due to its physical and mechanical treatment, while the following reaction proceeds with the formation of alumina cement (6)

An increase in particle grinding below 4 mm leads to a decrease in process productivity and an increase in energy consumption, and grinding a mixture of more than 7 mm reduces the strength of heat-resistant concrete.

For the manufacture of products, the mixture is then placed in molds in which the mixture is compacted on a vibrating stand, after which the molds with the mixture are dried in the chamber with hot air at a temperature of 150 ... 155 ° C for 6 hours, and the product is obtained from heat-resistant concrete with a strength of more than 85 ... 90 MPa:

Examples. Prototypes of concrete products were obtained on a bench installation (the technological scheme is shown in the drawing)

The technological scheme for the manufacture of heat-resistant concrete mixture and products from heat-resistant concrete mixture includes: 1 - the capacity of the spent solution for etching aluminum alloys (silumin); 2 - bunker of fireclay dust-entrainment; 3 - hopper of self-decaying slag of low-carbon ferrochrome; 4 - hopper of dump nickel slag; 5 - reactor with a high-speed stirrer; 6 - intermediate capacity; 7 - slurry pump for pumping the mixture; 8 - disintegrator; 9 - hopper of the finished mixture; 10 - vibration stand; 11 - dryer with samples; 12 - hot air fan; 13 - a rack.

1. In the reactor 5, equipped with a high-speed mixer, the spent etching solution of aluminum alloys (silumin) is loaded from the tank 1 in a predetermined volume, and their hopper 2, fireclay dust-fly, is fed into the reactor with the stirrer working, and the above reactions proceed (1 and 2), the temperature rises to 100 ... 120 ° C and liquid glass forms.

2. To prevent exceeding the content of the above alumina limits in the mixture, the calculated amount of self-dissolving slag of low-carbon ferrochrome, the calcium oxide of which binds the excess aluminum hydroxide to calcium aluminate, is charged simultaneously with the indicated reagents, while the temperature in the reactor rises to 150 ... 155 ° С and the above reactions (3 and 4) proceed with the formation of calcium aluminate and aluminosilicate binder (when the alumina in the mixture decreases below 4.0 wt.%, the concrete strength decreases and, while increasing its more than 6.0 wt.% slurry thickens).

3. After completion of the reactions (termination of steam evolution), the calculated amount of dump nickel slag is fed from the hopper 4 to the reactor 5, the mixture is mixed well and then transferred to the disintegrator 8 by the slurry pump 7, in which it is crushed to a particle size of 4 ... 7 mm and alumina cement and hardened aluminosilicate binder of the above composition are formed by reaction (5). In addition, astringents in the mixture increase due to the physicomechanical action of disintegrator grinders on it.

4. The mixture is filled to the specified size with a mixture of metal molds and the mixture is compacted by vibration of the molds on a vibrating stand 10, after which they are fed into the drying chamber 11, in which when drying with hot air supplied by a fan, the concrete mixture gains strength to the specified limits.

Four experiments were carried out to obtain concrete mix and products from it with a different ratio of components by mixing the spent etching solution of aluminum alloys, chamotte dust-fly and self-decaying slag of low-carbon ferrochrome in a laboratory reactor with a stirrer (until the evolution of steam ceases). Then, the calculated amount of dump nickel slag was fed into the reactor 5, and the mixture was ground in a laboratory disintegrator to 5 mm, and then dried at a temperature of 150 ° C in a muffle furnace for 6 hours.

After cooling the mixture, samples were formed from it — beams measuring 40 × 40 × 160 mm and samples — cubes 50 × 50 × 50 mm, and the mixture was compacted. After hardening for 24 hours under natural conditions, the samples were subjected to compressive strength tests. The test results are shown in table.2.

The data show that the claimed composition and method of manufacturing a concrete mixture and products from it is characterized by increased heat resistance (from 57-112 to 102-116 cycles) and product strength due to the intensification of the formation of aluminosilicate binder and alumina cement, as well as due to their physic - machining of concrete mixture in a disintegrator (from 40.4-82.4 to 85.1-91.2 MPa).

In addition, the proposed composition allows you to effectively use production waste that does not find wide industrial application, improve the environment, receive more durable heat-resistant concrete products. The method does not require high energy consumption for grinding components due to dump decaying slags and the use of more efficient equipment for the process — a reactor with a high-speed stirrer and a disintegrator.

Claims (2)

1. A method of manufacturing a heat-resistant concrete mixture, comprising mixing fireclay aggregate and self-decaying ferrochrome slag, characterized in that fireclay dust is used as fireclay aggregate in an amount of 11.1 ... 12.2%, self-decaying ferrochrome slag in an amount of 13, 8 ... 15.4%, in addition, add: the spent etching solution of aluminum alloys (silumin) - 40.0 ... 42.0% and dump nickel slag in the amount of 30.4 ... 35.1%, mixing is carried out in a reactor at pH 7.7 ... 8.5 and T = 150 ... 155 ° C, then the mixture is ground in a disintegrator particle size of 4 ... 7 mm. 2. A method of manufacturing products from a heat-resistant concrete mixture containing self-decaying ferrochrome slag and chamotte aggregate, including hardening, characterized in that the manufacture of the specified concrete mixture is carried out according to claim 1, compacted on a vibrating stand, and hardening is carried out by heat treatment in the chamber with hot air at a temperature of 150 ... 155 ° C for 6 hours.

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