Keywords: melting, industrial, silicon smelting, electric furnace, flue gas, purification, industrial electric furnace, low consumption, dust removal, emissions,

R & D of industrial silicon smelting furnace flue gas purification technology

　　industrial silicon flue gas control of electric furnace is currently the primary problem that governments at all levels attach great importance to and manufacturers urgently need to solve. 1 when it comes to flue gas treatment, we think of advanced governance technology and investment, how to deal with the problem. According to many years of production practice experience, the size of the amount of smoke produced has a great relationship with the manufacturer is technology and management. Enterprises with stable production technology and advanced management, high product quality, low consumption, good dust removal effect, and emission standards. Enterprises with poor technical management have poor product quality, high consumption and serious pollution. In the production process, in addition to the impact of equipment structure, the control of production operation technology directly affects the amount of flue gas in the electric furnace. At present, there are many people studying the value of recovering 1 tons of silicon micropowder, and few people studying the value of 1 tons of silicon in the furnace. To solve the economic and technical problems of industrial silicon manufacturers, thoroughly control flue gas and improve economic and social efficiency, the measures are:

　　(1) Reduce the amount of flue gas and improve the technical level of production operation. Improper operation technology is the main reason for the increase of smoke volume. The problem of most manufacturers is that the structure parameters of the electric furnace do not match, high voltage, high output, overload and wrong electricity caused serious fire, the ratio is not strict, and the improper smelting method causes serious fire. Industrial silicon smelting is carried out continuously in the state of electric furnace submerged arc. Arc closing operation shall be done during operation, timely feeding and ramming furnace, and the ratio of charge resistance and current voltage shall be adjusted. The advantages of arc closing operation are: the structure of the charge layer in the furnace can form a complete system, and the charge sinks in turn; Arc light is not exposed to maintain the blast furnace temperature; The electrode consumption is balanced and stable to avoid electrode breakage; The material surface temperature is low, which improves the utilization rate of electric furnace equipment; The amount of dust is less, which can make the electric furnace operation have a better environment. Regardless of the size of the electric furnace capacity, it can be closed arc operation, which is an important measure to reduce the amount of flue gas, improve the recovery rate of silicon, reduce consumption, and solve the vicious circle between operation and soot purification.

　　(2) the choice of flue gas purification equipment. Smelting 1 tons of industrial silicon produces about 2000-2600M3; The flue gas is mixed with a large amount of cold air after being burned at the furnace mouth. The silicon powder stays in the air for a long time, is not easy to settle, has large specific resistance, is oily, and its viscosity increases with the increase of temperature. Therefore, in order to purify and collect silicon powder, it is necessary to carry out a series of treatments such as secondary combustion cooling and pre-dust removal on the flue gas. Select 25-30M3 for the secondary combustion chamber of 6300KVA electric furnace;; Pre-dust collector adopts secondary cyclone dust collector; The heat exchanger is controlled by circulating feed water. Fan power is 180-250KVA; The dust collector adopts positive pressure large bag dust collector, and the equipment mostly adopts non-standard parts according to the actual situation.

　　(3) the principle of purification. A spark trapping device is used for full combustion to collect the unburned carbon particles with sparks, thus eliminating the possibility of sparks burning the filter bag. Some coarse particles are separated in the cyclone dust collector to reduce the amount of dust. Cooling is carried out through a heat exchanger to reduce the viscosity of silicon dust, and then it is sent to a bag filter by a fan. The silicon dust is filtered in the cloth bag, and the filtered pure gas is emptied.

　　(4) Investment estimation: The total investment cost includes steel flue, secondary combustion chamber, heat exchanger, filter bag room, filter bag, auxiliary equipment and civil engineering. Taking 6300KVA industrial silicon furnace as an example, the general investment only needs about 600000 yuan. The equipment mainly includes one high-temperature induced draft fan and 180-250KVA power motor. Other facilities adopt brick-concrete structure and non-standard steel according to the actual site, and the construction period is 2-3 months. 8000KVA industrial silicon electric furnace needs to invest about 800000 yuan.

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