ferrosilicon smelting operations power supply and raw materials

The power supply upstream of the ferrosilicon furnace is usually produced in a continuous way in an electric arc furnace. The current supplied by the transformer enters the furnace filled with charge through the electrode. During the entire melting process, the electrode is always inserted deeply and steadily into the charge, without setting an arc. The melting process relies on the heat of the arc and the heat of resistance that occur when the current passes through the electrode and charge.

The work must be carried out in strict accordance with the power supply system of the electric furnace. The electrode must be properly raised before power is applied. The three-phase ammeter should be balanced, and the current fluctuations should not exceed 25%. The voltage and current used in normal melting in electric furnaces of various capacities are about 84 V for 1800 kVA electric furnaces and about 96 V for 3200 kVA electric furnaces.

Electricity consumption per hour during normal smelting should be at least 5% of the load.

Distribution of raw materials

In the process of ferrosilicon smelting, a large amount of hot furnace gas is generated in the furnace. In order to fully utilize the energy of hot furnace gas, maintain good air permeability of raw materials, accelerate the chemical reaction in the furnace, increase the furnace temperature, and expand the "crucible", the surface of the material must be distributed in a wide and flat cone.

Controlling the appropriate surface height of raw materials, especially controlling the height of large raw material surfaces and maintaining a wide and flat cone, is a problem that needs to be paid attention to frequently during operation. If the surface of the raw material is too high, not only the silica in the furnace raw material will easily roll down to the bottom of the cone, but also the surrounding raw material will have poor air permeability, the depth of electrode insertion will decrease, the high temperature zone will move upwards, the heat loss will increase dramatically, the furnace bottom temperature will decrease, the "crucible" will decrease, the slag removal will be difficult, and the condition of the furnace will deteriorate. When the surface of the material is too low, and the surface of the raw material in the furnace core is flat and concave, on the one hand, the highly concentrated heat in the furnace core cannot be fully utilized, and a large amount of heat will be dissipated and wasted; On the other hand, the furnace surface is greatly reduced due to the high temperature, the resistance of the raw material is greatly reduced, the electrode insertion depth is greatly reduced, the "crucible" is reduced, the condition of the furnace is deteriorating, and the operating conditions are poor. As can be seen from the above, too high or too low the surface of the raw material is not conducive to smelting. Therefore, it is necessary to control the appropriate surface height of the raw materials. Generally, the surface height of the material should be close to the upper edge of the furnace mouth, and the height of the cone is 200-300mm.



When the permeability of the furnace is good, it can not only fully utilize the thermal energy of the high-temperature furnace gas to preheat the charge and reduce the silicon loss due to volatilization, but also help reduce the temperature gradient in the furnace, improve current distribution, ensure deep and stable electrode insertion, thereby expanding the "crucible". However, in fact, in The ferrosilicon smelting process is difficult to maintain good permeability in the furnace from start to finish. For example, a charge that is far from the electrode is easily permeable.

To eliminate the phenomenon of insufficient amount of reducing agent, it is necessary to stabilize the electrode, expand the cone, often punch the eye and carefully punch the furnace. When firing the kiln, a certain amount of coke should be added according to the actual situation and the amount of coke in the batch should be increased.

To eliminate the phenomenon of excess reducing agent, the amount of coke in the batch should be reduced and the control of the kiln wellhead should be strengthened. If the reducing agent is too excessive, an appropriate amount of silica can be added around the electrode. When silicon carbide is formed in the furnace, some iron filings can be added to break it down.

An excess or lack of reducing agent will reduce the "crucible" of the electric furnace, worsen the condition of the furnace, increase the electricity consumption of the electric furnace and reduce the rate of silicon recovery. Therefore, it is necessary to maintain an appropriate carbon content.