RU2681172C2 - Method of producing mineral wool - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing mineral wool. Method for producing mineral wool includes loading fuel, mineral raw materials into a furnace, melting mineral raw materials and producing mineral wool. In the quality of the fuel in the first alternative, a mixture of cinders of baked anodes with a coal lining scrap is used with the following ratio of components: 75–95 % by weight of calcined anodes, 5–25 % by weight of coal lining scrap. According to the second alternative, a mixture of butt ends of baked anodes with coal lining scrap and coke is used as fuel in the following ratio of components: 45–90 % by weight of calcined anodes, 5–30 % by weight of coal lining scrap, 5–25 % by weight of coke.

EFFECT: technical result is the expansion of the raw material base of the fuel to produce mineral wool, increasing heat transfer, recycling aluminium production waste, reducing emissions of harmful gases into the atmosphere.

1 cl, 2 tbl, 5 ex

Description

The invention relates to the production of heat-insulating materials during the melting of raw materials in cupola furnaces, and in particular to fuel for the production of mineral wool used for heat and sound insulation.

A known method of cupola melting of cast iron and oxide materials on anthracite, including loading materials into the cupola shaft and supplying blast into the oxygen zone, which allows replacing coke with anthracite (patent RU 2335718. IPC F27B 1/00, С21С 1/08, publ. 10.10.2008 .). The main disadvantage of the method of melting on anthracite is its low thermal stability, as a result of which, upon rapid heating above 800 degrees Celsius in the cupola and high pressure of the column of the metal charge, it cracks into small pieces, which reduce the free section of the cupola and lead to disruption of the melting course, and even turn into dust, the oxygen channels clog; as a result, the fire goes out and the melt freezes, which leads to failure of the entire cupola, it is necessary to manually knock out the solidified melt from the inside.

A known method of producing mineral wool (MF Sukharev et al. "Production of heat-insulating materials", "Higher School", 1981, p. 32-59), including loading the source of mineral raw materials - blast furnace slag, in a cupola. To increase the acidity modulus, a correcting additive - a deoxidizer (diorite), which has a higher acidity modulus than the initial mineral raw material, has been added to the composition of mineral raw materials. Foundry (or blast-furnace grains larger than 40 mm) coke are used as fuel. The disadvantage of this method is that mineral wool has a small acidity module - not more than 1.2-1.25, as well as high coke consumption, which is an expensive component. The disadvantages of this method include the need to use a special deoxidizing additive, melting and uniform mixing of which with the main component of the smelting - molten blast furnace slag is an additional problem.

A known method for cupola melting of cast iron and oxide materials on lean coals, including loading charge materials and fuel into fuel spikes, supplying blast heated to 450-550 ° C, in which a mixture of 40% birch wood and 60% lean coal is used as fuel at a height loading materials into the cupola 4.0-4.5 m. (Pat. RF No. 2407804, IPC С21С 1/08, С03В 5/12, publ. 12/27/2010.). The disadvantage of this method is its high reactivity, which is associated with the enormous porosity (80-87%) of lean coals, which negatively affects the reliability of operation, since at temperatures above 800 ° C, it quickly burns up or breaks down, which leads to clogging of the oxygen channels charge.

A known method of producing mineral wool (Pat. RF №2439006, IPC С03С 13/06, publ. 01/10/2012.), Which includes loading into the cupola cupola source mineral raw materials, fuel and deoxidizing additives, melting mineral raw materials and producing mineral wool, coke obtained from a mixture containing a product of delayed semicoking of heavy oil residues is used as fuel. The disadvantage of this method is the appearance of caustic dense smoke at the initial stage of ignition with the release of sticky volatile substances and low mechanical strength of semi-coked oil residues, which can lead to solidification of the molten melt in the charge due to its cooling.

Closest to the claimed (prototype) is a method of producing mineral wool according to the patent of the Russian Federation No. 2238332 (IPC C03B 37/06, C03C 13/06, publ. 03/20/2005.), Which includes loading into the furnace the source of mineral raw materials and fuel, melting of mineral raw materials and production of mineral wool, where a mixture of coke, lean coal and / or anthracite is used as fuel. A disadvantage of the known solution is low mechanical strength, at combustion temperatures above 800 ° C, as well as a small acidity modulus of the final product - mineral wool.

The task is to expand the raw material base of fuel for producing mineral wool, to reduce the cost of the production process, increase heat transfer, utilize aluminum waste, and reduce the emission of harmful gases into the atmosphere.

The problem is solved in that in the method of producing mineral wool, including loading fuel, mineral feed into the furnace, melting mineral raw materials and producing mineral wool, according to the invention, cinder anodes or a mixture of fired anodes with a scrap of coal lining are used as fuel, or a mixture of cinders of calcined anodes with scrap coal lining and coke, or a mixture of scrap coal lining with coke. Moreover, cinder anodes and scrap coal lining are used with a ratio of components from 75 to 95 and from 5 to 25 wt. % respectively. Or cinders of calcined anodes, scrap coal lining and coke are used with a ratio of components from 45 to 90, from 5 to 30, and from 5 to 25 wt. % respectively. Or scrap coal lining and coke are used with a ratio of components from 5 to 50, and from 50 to 95 wt. % respectively.

The claimed method differs from the prototype in that, in the fuel composition, in the charge melting, the method of producing mineral wool uses cinder anodes and / or coal lining scrap - aluminum production wastes, or mixed with each other and with coke.

From the prior art, the use of electrode combat as an additive for cupolas is known, however, in the known technical solutions, it performs the function of a single spike, that is, as a nozzle for passing oxygen. For example:

в патенте РФ №2186122 - электродный бой в количестве 15-25% используют в качестве огнеупорной насадки в газовых вагранках с огнеупорной насадкой, и используется как источник углерода для обогащения науглероживания чугуна, а не как топливо.

in the patent of the Russian Federation No. 2186122 - an electrode fight in the amount of 15-25% is used as a refractory nozzle in gas cupolas with a refractory nozzle, and is used as a carbon source for enrichment of carbonization of cast iron, and not as fuel.

в патенте РФ №2044059 - графитовый материал в газовых вагранках используется для поддержания температуры выделяемой при сжигании газа в вагранке, то есть, как и в патенте РФ №2186122 не подразумевается использование электродного боя как самостоятельного топлива.

in the patent of the Russian Federation No. 2044059 - graphite material in gas cupola is used to maintain the temperature emitted when burning gas in the cupola, that is, as in the patent of the Russian Federation No. 2186122, the use of electrode combat as an independent fuel is not implied.

в патенте РФ2194230 - предлагает использование электродной стружки в составе подины газовой вагранки для повышения вязкости расплава, по средствам внедрения окиси алюминия через стружку и не подразумевает использования электродного боя как самостоятельное топливо.

in patent RF2194230 - proposes the use of electrode chips in the hearth of a gas cupola to increase the viscosity of the melt, by means of introducing aluminum oxide through the chips and does not imply the use of electrode combat as an independent fuel.

в патенте РФ №2243465 - предлагают использовать как огнеупорная холостая колоша для повышения содержания углерода в чугуне, и не подразумевает использования электродного боя как самостоятельное топливо.

in the patent of the Russian Federation No. 2243465 - it is proposed to be used as a refractory blank spike to increase the carbon content in cast iron, and does not imply the use of electrode combat as an independent fuel.

в патенте РФ №2219450 - в составе холостой огнеупорной колоши газовой вагранки используют коксовые брикеты и отходы механической обработки заготовок графитизированной продукции, спрессованных и спеченных при температуре спекания 1300-1350°С, но температура расплава минеральной ваты больше 1350°С, что в совокупности с механической нагрузкой приводит к разрушению брикетов, закупориванию воздушных каналов в вагранки и последующему затвердеванию расплава. Заявляемое изобретение лишено таких недостатков, так как не разрушается при механических нагрузках и температурах выше 1500°С.

in the patent of the Russian Federation No. 2219450 - in the composition of the blank refractory ears of the gas cupola, coke briquettes and waste from the mechanical treatment of graphitized products blanks pressed and sintered at a sintering temperature of 1300-1350 ° C are used, but the temperature of the mineral wool melt is more than 1350 ° C, which together with mechanical load leads to the destruction of briquettes, clogging of the air channels in cupola furnaces and the subsequent solidification of the melt. The claimed invention is devoid of such disadvantages, as it does not collapse under mechanical loads and temperatures above 1500 ° C.

Thus, in the known methods, the use of scrap of coal lining and / or cinders of calcined anodes as an independent fuel is not known, that is, from the prior art, solutions having features matching the distinguishing features of the claimed invention have not been identified, which allows us to conclude that the claimed invention meets the condition of patentability "inventive step".

Anodes are consumables of electrolyzers in which aluminum is smelted from alumina. Calcined anodes differ from ordinary ones by lower energy consumption during smelting (aluminum smelting is the most energy-consuming process in all metallurgy), as well as their environmental friendliness, significantly reducing emissions of gases and extremely harmful resinous substances into the atmosphere.

Cinders of annealed anodes are obtained by working off annealed anodes in electrolytic cells of aluminum plants and have the following properties: physical state - solid; carbon content from 80%; total sulfur content from 0.5% to 3%; aluminum oxide content from 0.5 to 2%; ash content up to 20%; iron content from 0.05 to 0.4; humidity from 0.3 to 2.5%; others up to 8%; dimension from 100 mm.

The scrap of the coal lining of aluminum electrolysis cells is obtained in the production of primary aluminum, during which, during the electrolysis of cryolite - alumina charge, the coal part of the cathode lining becomes unusable. During the overhaul of the cathode assembly of the electrolyzer, the spent lining is removed using a hydraulic hammer from the cathode casing and replaced with a new one.

Scrap coal lining consists of: sodium - from 6 to 10%; aluminum from 1 to 8%; aluminum oxide from 4 to 10%; carbon from 60 to 80.1%; silicon (dioxide) - from 3 to 7%; iron (oxide) - from 0.4 to 1.5%; others up to 20%.

The optimum particle size distribution of the fuel mixture entering the cupola is the fraction (90 ÷ 240) mm, the flakiness is not lower than 2 groups according to GOST 8267-93 in edition No. 3 of 04.24.2002.

The inventive method is illustrated by examples, the results of which are given in tables.

During industrial tests, to determine the effectiveness of the cupola furnace, the dosage of coke, scrap of coal lining, and calcined anode cinders increased from 5% to 100% in proportions in increments of 5%.

The characteristics and chemical composition of fuel ash and mineral components are given in table 1.

In table 1, the following notation is used:

C is carbon, wt. %;

D is the size of the pieces of fuel, mm

Embodiments of the embodiments below.

Mode 1 - the existing mode of operation of a cupola furnace for the production of mineral wool. In modes 2, 3, 4, 5, the obtained results of tests performed at existing plants producing mineral wool are shown. Measurements were made using automated systems included in the plant's automated process control system.

The purpose of the experiment: Reduction of energy consumption in obtaining heat energy, due to the use of aluminum production waste (coal lining scrap and calcined anode cinders) as a fuel in mineral wool production as fuel.

The raw material for the production of mineral wool is gabbro-diabase, dolomite, slag.

 Gabbro Diabase - 58%  Dolomite - 13%  Slag - 29%

1. For comparison, during the experiment in the existing operating mode, taken as a control, the following was used as fuel:

 Coke - one hundred%

2. When conducting an industrial experiment, the following composition was used as fuel:

 Coke - fifty%  Coal lining scrap - fifty%

When a scrap of coal lining is introduced into the fuel component of the charge, the temperature of the melt and the temperature of the gases at the outlet increase.

3. Operating mode 3. When conducting an industrial experiment, the following composition was used as fuel:

 Coke - 25%  Coal lining scrap - thirty%  Cinder Anodes - 45%

4. In an industrial experiment, fuel was used

 Cinder Anodes - one hundred%

When cinder anodes are introduced into the fuel component of the charge, the temperature of the melt and the temperature of the gases at the outlet increase.

5. When conducting an industrial experiment, the following composition was used as fuel:

 Coal lining scrap - 25%  Cinder Anodes - 75%

The experiment showed that it is possible to use scrap coal lining and cinders of calcined anodes in mineral wool production. During the experiment, there is no decrease in performance. The temperature and viscosity of the melt were within the bounds of the technological map of the cupola furnace for producing mineral wool. The physical and mechanical parameters of the products correspond to TU, fuel consumption decreased to 23% with the addition of coke + scrap of coal lining + cinder, coke + scrap of coal lining, cinder of annealed anodes + scrap of coal lining, cinder of annealed anodes while maintaining the same performance.

The temperature in the furnace does not drop. The air entering through the tuyeres interacts with the carbon of the fuel by the reactions:

С + 0.5О ₂ = СО + 110964 kJ / mol;

C + O ₂ = CO ₂ + 395052 kJ / mol.

The resulting CO in the presence of free oxygen burns out:

CO + 0.5O ₂ = CO ₂ + 248088 kJ / mol.

At the surface of the pieces of fuel, the concentration of CO ₂ and the temperature of the gases increase. CO ₂ will move into the gas stream, where its concentration is low. Partially, CO ₂ interacts with the hot carbon of the fuel by the reaction:

С + СО ₂ = 2СО - 173124 kJ / mol.

There is free oxygen O ₂ which burns to CO ₂ , i.e. the gas stream is enriched in CO ₂ and depleted in oxygen. The cupola zone where there is free oxygen is called the oxygen zone. At the end of the oxygen zone, the gas temperature reaches its maximum, the process of CO ₂ reduction with heat absorption and with an increase in the CO content is enhanced. The cupola zone, where the concentration of CO in cupola gases increases, is called the reduction zone. Thus, the active part of the cupola located from the tuyeres to the melting zone can conditionally be divided into two zones: oxygen, where the gas stream still contains O ₂ and combustion ends mainly with the formation of CO ₂ , and the reduction, where there is practically no free oxygen, the products combustion is enriched with CO due to the reduction of CO ₂ . These factors affect the processes in the furnace.

Scrap of the coal lining and cinder of annealed anodes are necessary to replenish the fuel part of the cupola and reduce fuel consumption, since they are very dense and burn slowly, so the fuel burns out in the cupola more slowly, but at the same time they have greater heat transfer, which is proved by experiment, thereby reducing the yield harmful gases into the atmosphere and coke consumption due to higher heat transfer. You can work on a 100% cinder of calcined anodes, with oxygen supply at a blast temperature of at least 630 ° C.

Table 2 shows the results of monitoring atmospheric emissions at existing plants producing mineral wool. Measurements were made using automated systems included in the plant's automated process control system.

When using aluminum waste instead of coke as fuel for a cupola furnace, a reduction in harmful emissions into the atmosphere is observed.

Unlike coke coal briquettes, when combustion temperatures are reached above 1000 degrees Celsius and external mechanical stresses, pieces of aluminum waste are not destroyed, but, on the contrary, there is a uniform and gradual fading with maintaining the desired temperature;

Unlike coke, aluminum production wastes have a rhomboid shape, burn out longer, give a higher temperature, which allows air to pass through the charge better and in large quantities, as a result of which the melt of mineral raw materials is faster.

Replacing part of the coke in the fuel with cinder anodes and / or scrap of carbon electrodes can not only save on expensive foundry coke for the manufacturing process of mineral wool, but also reduces the number of additives used in the composition of the mineral raw materials, providing the necessary acidity modulus of the resulting final product - Mineral kata, as well as to eliminate huge waste landfills of aluminum production - cinders of calcined anodes and / or coal scrap electrodes.

The claimed invention allows to solve the problem of expanding the raw material base of fuel for producing mineral wool, reducing the cost of the production process, increasing heat transfer, recycling aluminum production wastes, and reducing the emission of harmful gases into the atmosphere.

Claims (4)

A method of producing mineral wool, including loading fuel, initial mineral raw materials into a furnace, melting mineral raw materials and producing mineral wool, characterized in that a mixture of calcined anodes with scrap of coal lining is used as fuel in the following ratio, wt.%: cinder anodes                 75-95 coal lining scrap                   5-25 or a mixture of cinders of calcined anodes with a scrap of coal lining and coke in the following ratio of components, wt.%: cinder anodes                 45-90 coal lining scrap                   5-30 coke                                                       5-25