Quality of Anode. Overview of Problems and Some Methods of their Solution Part 2. Improving the quality of the anode

Abstract

Laboratory studies have shown that charging the components of the anode mass increases the rate of wetting and impregnation of dust by the pitch in 2-3 times, as evidenced by the shorter time interval during which the moistened coke was immersed in the pitch melt. The algorithm for obtaining anode mass according to the proposed technological scheme is the following. The components of coke batch - bunches of different fractional composition from bunkers 2 by metering devices 3 and transport screws 5 are fed to preheater 6 where they are heated to a temperature of 200-220 ° C. Further, the heated components of the coke batch are fed into the mixer 11. Coke dust before entering the mixer 11 by the dispenser 4 from the bunker 1 is fed into the dust preheater 9 where it is also heated to a temperature of 200-220 ° C. Pitch, preheated to a temperature of 200-2400C, is fed into the dispenser 8. Further heated coke dust and pitch enter high-voltage charging units 7, where they acquire electrical charges for 1-3 seconds, pitch-negative, and coke dust-positive. At the same time, the voltage at the electrodes of high-voltage charging stations is in the range of 24000-50000 V DC. Charged in this way, pitch and coke dust also enter mixer 11, where they are mixed for 3-4 minutes with each other and with coke batch. From the mixer 11, the finished anode mass is fed into the extruder 10 to form briquettes. In general, the process of anode preparation takes 4-5 minutes, which is 2 times lower than with "traditional" technology. The presented technology allows essentially to raise productivity of the manufacture equipment of an anode mass at the expense of time reduction of mixing more than in 2 times. Reducing the mixing time of components reduces the specific electricity consumption for anode production by 20-25 kW / t, taking into account the energy consumption of the high-voltage charging unit. An increase in the degree of impregnation of coke dust with pitch reduces the anode fall-off under the conditions of the active electrolyzer and reduces the yield of coal foam by 5-7 kg / ton of Al. Reducing the yield of coal foam reduces the time of the electrolyzer in the depressurized state by an average of 0.2-0.25 hours during the day, which reduces the specific fluoride emissions by 0.1-0.2 kg / ton Al.