SU1025747A1 - Method for smelting ferrosilicon in closed electric furnaces - Google Patents

Description

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This invention relates to ferrous metallurgy, in particular to ferroalloy production, and relates to the smelting of ferrosilicon.

There is a known method of smelting ferrosilicon, which includes loading of a charge consisting of quartzite, chips, and a yaride reductant, manually or with a charging machine on the furnace top. In this case, a cone of the charge is formed around the electrodes, and the reducing agent in the column is taken with an excess in comparison with the stoichiometrically necessary amount.

The mixture is continuously smelted with periodic releases of metal and slag from the furnace.

The disadvantage of this method is the gradual disruption of the furnace due to the sintering of the top furnace, due to a decrease in electrical resistance and a decrease in the depth of immersion of the electrodes due to the increased content of carbonaceous materials around the electrodes.

There is also known a method of smelting ferrosilicon, including the continuous introduction of the charge into the gap between the electrodes and the roof. The carbon content in the charge is also in excess of the calculation for the complete recovery of silicon from quartzite h.

The mixture is continuously smelted with periodic releases of metal and slag 2.

For this method, an increase in the content of carbonaceous materials around the electrodes is characteristic, and hence the sintering of the furnace top, the formation of fistula gas plumes on it, and as a result, there are periodic breakdowns in the course of electric furnaces.

The closest to the proposed technical essence and the achieved effect is a method of smelting ferrosilicon in closed electric furnaces, which includes feeding a mixture with a carbonaceous reductant to the head, and the missing amount of C + O-SO) is continuously fed to the mixture to the electrodes, supporting around them a layer 100-200 mm thick. The mixture is continuously smelted and periodically release metal and slag 3.

A disadvantage of the known method is that the presence of an excess carbonaceous reductant at the electrodes leads to a fast and abrupt

the drop in the electrical resistance of the entire bath and the corresponding drop in the power of the furnace, and the lack of a reducing agent in the rest of the charge causes its sintering in the center and on the periphery of the furnace. In addition, when smelting ferrosilicon in powerful furnaces due to the difference in the sizes of quartzite and coke in the cones at the electrodes

 stratification of the charge, the electrodes form layers with an excess of coke, and at the soles of the cones - with a deficiency. With the growth of furnace power, the size of the cones and the stratification of the charge in them increase, which leads to destabilization of the process and a decrease in the technical and economic indicators of the smelting of ferrosilicon in large furnaces compared to less powerful ones.

0 The purpose of the invention is to reduce specific energy consumption and increase productivity.

This goal is achieved by the fact that according to the method of smelting ferrosilicon in closed electric furnaces, which includes supplying the charge with a carbonaceous reducing agent to the top of the furnace and the carbonaceous amount of the reducing agent to the mixture, continuous melting of the mixture and periodic metal and slag emissions, the mixture is supplied with the content of carbonaceous reducing agent 0 , 98 from the required, and the rest

5, part of it is periodically fed into the furnace during the penetration on the soles of the charge cones.

When commissioning a closed electric furnace of 63 MVA, the harmful effects

0 stratification of the charge leads to a sharp destabilization of the process. When a calculated amount of coke is introduced into the mixture (150-155 kg per 300 kg of quartzite), an area with low electrical resistance is formed at the electrodes for several days. The current load increases sharply, which leads to the need to switch to low voltage and turn off the CPC with a corresponding loss of power and technical and economic indicators.

A study was made of the content of coke in the charge cone near the electrodes during the smelting of ferrosilicon, and its empirical dependence was found (in% of the given distance from the electrode

K 208-P4g. The analysis of this dependence and the actual measurements of noKa3biBarot, that for a 63 MVA furnace, the distance from the electrode to the end of the sole of the cone t, 5 m, when 15Q kg of coke are added to the charge, at the electrode, in a layer 1 m thick, the mixture will go off with the average content of reducing agent about 17 kg. In order to reduce the coke content to 150 kg, you need to enter it within 137 kg into the initial mixture, and give the total OS in the outer layer with an additive. Further Research; The results of which are given in the examples confirmed this position and allowed us to specify the limits of the content of the reducing agent in the charge loaded under the electrodes and the weight of the cdx additives on the soles of the cones. For closed high-power electric furnaces, the content of the reducing agent in the stack above 98 calculated does not stabilize the process, but below 80 leads to its lack at the electrodes and to the breakdown of the technological course. Examples The testing was carried out on a 63 MIA round closed three-electron furnace, producing 10 7 sh kS% ferrosilicon. From furnace pockets, the charge 1 is supplied by the 5 trubottechki to the loading hoppers of the vault, under which they form cones with dimensions from the electrode to the base 1, 7 m. During the research, the coke content in the charge charged through the funnel reduces-c, and the amount missing from the calculation (from 2.0 to 6.0 tons) is set 1 time per shift to the soles of the cones. The electric furnace operates with a linear voltage of 220-250 V and an active power from kQ to 50 MW. In the first case, coke in the amount of 150 kg is added to 300 kg of quartzite at the rate of the usual excess (102-104). In the near-electrode cones, the charge stratifies and a layer of carbon rich in the electrodes forms. So will melt by a known method. Subsequently, part of the coke coke is removed and set on the soles of the charge cones at the electrodes. The results of the furnace are given in the table.

Kiln operation, days Coke content in kg

The content of the reducing agent in koloshe,% of the calculated Coke on the base of the cones, t / day

The content of the reducing agent in the charge, to the estimated

Specific power consumption, kW. h / t

Productivity, t / day

The best results were obtained by reducing the weight of coke to kg (93-9t from the estimated required),

nineteen

22

H5 120 110

150

5.1 8.0 18.2 16.7

102.3 101.5 103.2 10A, 1 101.0

6300

5010 5070 5980

129.9 203.9 215.3 138.5 155.0

55

and satisfactory results were obtained in the range of 80-98. Above and below these limits electric furnace

510257 in

sharply worsens its work, and its energy consumption, and at 6-b5

indicators are falling. improve performance.

The proposed method allows

stabilize the smelting process Expected economic effect

ferrosilicon in powerful enclosed elec- ters of 1t of about 320 thousand rubles. in year

tropiche, at 5-25 to reduce the specific one electric furnace with a capacity of 63 MVD.

Claims (1)

METHOD OF FERROSILICIUM Smelting in closed electric furnaces, including feeding a mixture with a lack of a carbon reducing agent to the top and a missing amount of a carbon reducing agent per charge, continuous melting of the mixture and periodic releases of metal and slag ”characterized in that, in order to reduce specific energy consumption. the mixture is introduced with a carbon reducing agent content of 0.80-0.98 of the required, and the rest of it is periodically fed into the furnace during penetration on the soles of onus charge. and,. ,, 1025747 I