A method for preparing high-quality mullite by coal gangue electrothermal method

Abstract

A method for preparing high-quality mullite by electrothermal method of coal gangue, which is carried out according to the following steps: (1) pulverize the calcined coal gangue, carbonaceous reducing agent and additives respectively; Powder, carbonaceous reducing agent powder and additive powder are mixed with water and pressed into agglomerates; (3) drying to remove moisture, and placing them in a submerged arc furnace for electrothermal smelting at a temperature of 1000-2000 °C. (4) Physically separate the mullite slag phase from the metal phase; then pickle and purify the mullite slag phase to produce high-quality mullite. The method of the invention improves the economic added value of coal gangue, reduces the accumulation of solid waste, has wide source of raw materials, low price, short process flow, low production cost and low energy consumption.

Description

technical field [0001] The invention belongs to the field of solid waste recovery, in particular to a method for preparing high-quality mullite by electrothermal method of coal gangue. Background technique [0002] Coal gangue is solid waste generated during coal production and processing, and is a symbiotic resource of coal. It is associated with coal during the coal formation process. The ash content is usually greater than 50%, and the calorific value is generally 3.5-3.8MJ / kg; according to statistics, its emissions The amount is about 15% to 20% of the raw coal output of coal mines. The stacking of coal gangue in my country has formed more than 1,500 gangue hills. The gangue stored in coal mines in the country is about 4 billion tons or more, covering an area of ​​nearly 300,000 mu. With the development of the coal industry With continuous development, the amount of gangue discharged from mines is increasing day by day, and the amount of accumulation is increasing year by ...

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Problems solved by technology

[0003] At present, the method of dealing with coal gangue in my country is mainly a large amount of simple stacking or arbitrary discharge, and a small part is used for the synthesis of organic compound fertilizers, the preparation of kaolin, zeolite molecular sieve or rubber and plastic fillers and other industrial fields, and the recycling rate is extremely low; coal gangue caused The pollution mainly includes air pollution, leaching pollution, radioactive element pollution, geological disasters and coal gangue explosion, etc., which have caused a huge impact and damage to our country's environment and human health.

[0004] Mullite is an aluminosilicate mineral of aluminum with a composition in the 2Al 2 o 3 ·SiO2 2 to 3Al 2 o 3 ·SiO2 2 Between, its Al 2 o 3 The content ranges from 62 to 100%, which is a high aluminum material; 3Al 2 o 3 ·SiO2 2 Mullite has a low elastic modulus of 200GPa, which is about Al 2 o 3 , half of SiC; thermal expansion coefficient is small, about Al 2 o 3 , ZrO 2 Half of that of SiC, which is similar to SiC; therefore, mullite has excellent properties such as high refractoriness, high load softening temperature, thermal shock resistance, chemical corrosion resistance, good creep resistance, volume stability, and strong electrical insulation. It is an ideal high-grade refractory material and is widely used in metallurgy, glass, ceramics, chemical industry, electric power, national defense and other fields; at present, the industrial preparation of high-quality mullite mainly adopts wet chemical method or by adding LiF, AlF 3 and other additives to realize the low-temperature synthesis of mullite, but the process parameters are not easy to control, the production cycle is long, and it is difficult to meet the requirements of large-scale production

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