RU2052403C1 - Method for burning solid fuel and melting of slag - Google Patents

Abstract

FIELD: production of devitrified glass slags. SUBSTANCE: method involves loading solid fuel into a furnace and, additionally, limestone, ash-slag waste and sodium sulfate in a relation, wt.-%: solid fuel, 45-62; limestone, 35-30; ash-slag waste,18-5; sodium sulfate, the balance. Fuel is coal containing up to 15 wt.-% of CaO + MgO while ash-slag waste - spent material of thermal power stations running on said coals. Bubbling proceeds at an intensity of 250-2500 nm⁶ of gas per 1m³ of melt. EFFECT: higher efficiency. 3 tbl

Description

 The invention relates to a power system and the construction industry and can be used to produce slag metal when burning solid fuel in a bubbled melt.

 In the power industry, when burning solid fuels at thermal power plants, a huge amount of ash and slag waste is generated, which is practically not disposed of and thrown into ash dumps. These wastes contain a significant amount of oxides of silicon, aluminum, calcium, magnesium, iron, non-ferrous metals and are of great economic importance for the production of various building materials. Of particular interest is the use of ash and slag waste for the production of slag metal, which in their performance is significantly superior to materials such as ceramics, stemalite, stone casting, etc.

A known method of burning solid fuel and obtaining slag by sparging an oxygen-containing oxidizing agent through a melt bath with a blast intensity of 2800-3000 nm ³ / h · m ³ and the fuel supply to the melt from above.

 The disadvantage of this method of producing acidic slag silicate melt, which without additional refinement cannot be used for specific purposes of obtaining building materials, including for the production of slag metals. The completion of the slag melt outside the furnace unit after its release requires large energy, capital and operating costs.

 The purpose of the invention is the production of slag melt in the form of finished slag metal and the creation of technology as close to waste-free as possible.

This is achieved by the fact that in the method of burning solid fuel and smelting the slag by sparging an oxygen-containing oxidizing agent through a molten bath and supplying fuel to the melt from above, bubbling is carried out with an intensity of 250-2500 nm ³ / gas per 1 m ^{3 of} melt, fuel containing in the mineral part the sum of calcium and magnesium oxides up to 15 wt. served together with limestone, ash and slag waste from thermal power plants and sodium sulfate in the ratio, wt. solid fuel 45-62; limestone 30-35; ash and slag waste of thermal power plants 5-18; sodium sulfate rest. Coals with a content of calcium and magnesium oxides of up to 15 wt.% In its ash are used as solid fuel. and as ash and slag waste, waste from thermal power plants operating on the same coal. When additives exceed the declared limits, slag will be obtained that does not meet the OST requirement for slag metals or the content of the sum of calcium and magnesium oxides 40-45 wt. or the content of the sum of silicon oxides and aluminum 45-50 wt. which is confirmed by the calculated data given in table 1. The calculations were performed when burning Donetsk coal grade ASH with the chemical composition of ash, wt. SiO ₂ 51.4; Al ₂ O ₃ 22.4; Fe ₂ O ₃ 15.3; CaO 3.8; MgO 1.6; TiO ₂ 0.7; K ₂ O 3,3; Na ₂ O 1.5. As ash and slag waste accepted waste from the ash dump with chemical composition, wt. SiO ₂ 42.9; Al ₂ O ₃ 17.2; Fe ₂ O ₃ 11.2; CaO 3.7; MgO 1.4; TiO ₂ 1.5; K ₂ O 2,9; Na ₂ O 1.4; C 17.8. In the calculations, it is assumed that the carbon of fuel and ash and slag waste burns completely, and the extraction of iron in the metallized phase (matte) is 90 wt.

Table 2 shows the calculation of the yield and composition of slag components loaded into the furnace per 100 kg of each component. According to semi-industrial tests of coal combustion, it is accepted that the carbon of fuel and ash and slag waste of Donetsk coal of the ASh grade of chemical composition mentioned above burns out completely, and the extraction of iron into the metal phase is 90 wt. It is also assumed in the calculation that the CaO yield from limestone is 56 wt. and Na ₂ O from sodium sulfate, respectively, 43.6 wt. The data in table 2 are the source for calculating the composition of the slag obtained as a result of coal combustion and smelting. This calculation is shown in table 3, according to which examples 2 and 4 correspond to the boundary conditions of the range of values for coal and limestone, and example 3 is intermediate. The data of these examples correspond to the OST requirements for slag metals in the content of the sum of oxides CaO + MgO = 40-45 wt. and oxides SiO ₂ + Al ₂ O ₃ = 45-60 wt.

 Example 1 is prohibitive in the lower value of coal and the upper value of limestone and ash, resulting in slag with an excess of the sum of oxides CaO + MgO = 45.2 wt.

Example 5 is prohibitive in the upper value of coal and the lower value of limestone and ash, resulting in a slag with an excess of the sum of oxides SiO ₂ + Al ₂ O ₃ = 50.22 wt.

Czhiganie solid fuel and smelting the slag by bubbling an oxygen-containing gas through the molten bath with the blast intensity of less than 250 Nm ³ / · h per 1 m ³ of the melt leads to incomplete combustion of carbon fuels and deficiency of heat bubbling the melt that will lead to melt freezing and stop the process .

The burning of fuel with an oxygen-containing gas supply rate of more than 2500 nm ³ / h per 1 m ^{3 of} melt to the melt bath will lead to excessive melt blowing, increased spray absorption, incomplete absorption of oxygen in the melt and mechanical burning of the fuel, which will sharply reduce the technical and economic performance of the fuel combustion process .

 The method is as follows.

Fuel (coal) is fed from above to the furnace through an intensively sparged oxygen-containing blast slag melt through the loading devices. At the same time, limestone, ash and slag waste from thermal power plants and sodium sulfate are loaded into the furnace in a predetermined proportion. In the process of burning fuel in a bubbling melt due to oxygen from the blast, supplied through tuyeres with an intensity of 250-2500 nm ³ / h · m ³ , the combustible components of the fuel are burned and its mineral part, limestone and ash and slag are melted. Due to the fact that the fuel combustion process is carried out in a reducing atmosphere (oxygen excess coefficient α≈0.95, iron and other metals of the mineral part of the fuel and ash and slag are recovered and the melt is divided into metallized (matte) and non-metallized (slag) phases. and limestone fuel additive The liquid homogeneous slag obtained during the smelting process, corresponding to the composition of slag crystals, is discharged through a slag siphon for the production of slag metal products, matte (metal alloy) is periodically removed from the process through special devices for further processing, and high-temperature gases with a temperature of ≈1450 ^о С are sent to a recycling plant to generate heat energy.

The proposed method of solid fuel combustion and slag smelting is implemented in a pilot plant with a cross-sectional area of 2 m ² in the area of blast tuyeres. 1000 kg / h of coal (Donetsk ASh) with a carbon content of 30.5 wt. and ash content Ap = 38.5 wt. 600 kg / h of limestone (CaO = 56 wt.), 150 kg / h of ash and slag waste from Kharkov State District Power Station-2, and 35 kg / h of sodium sulfate were added to coal. The melt was sparged with oxygen enriched (O ₂ = 45 vol.) Air with a flow rate of 1400 nm ³ / h. The slag melt was discharged through the slag hole, and the metallized phase through the matte hole. As a result of tests, a slag melt of medium composition was obtained, wt. CaO + MgO = 42.57; SiO ₂ + Al ₂ O ₃ = 49.17; K ₂ O + Na ₂ O = 5.3, which corresponds to the OST requirement for slag metals.

 Using the proposed method of burning solid fuel and smelting slag in the form of slag metal allows, in comparison with the prototype, to obtain slag in the form of a finished product for the production of slag metal products.

Claims (1)

METHOD FOR BURNING SOLID FUEL AND MELTING SLAG by bubbling an oxygen-containing gas through a bath of silicate melt and supplying fuel to the melt from above, characterized in that the bubbling is carried out with an intensity of 250 - 2500 nm ³ gas per 1 m ^{3 of} melt, fuel with a total amount of oxides in the mineral part calcium and magnesium up to 15 wt.% served together with limestone, ash and slag waste from thermal power plants and sodium sulfate in the ratio, wt.%:
Solid fuel with a content of CaO and MgO up to 15 wt.% - 45 - 62
Limestone - 30 - 35
Ash and slag waste from thermal power plants - 5 - 18
Sodium Sulfate - Else

Images