Technology--Key influencing factors and process technology optimization of prebaked anode quality (Part 2)

In the previous article, "Technology--Key influencing factors and process technology optimization of prebaked anode quality (Part 1)", we mainly expounded the influence of raw material quality and process technology on the quality of prebaked anodes. This article continues to explore the optimization of anode calcination, forming, roasting and other process technologies immediately before the previous article, for the reference of enterprises.

1. Optimization of calcination process

1.1. Improve the batching accuracy of petroleum coke

Almost all of the petroleum coke batching scales designed by the project have the problems of poor weighing accuracy and inability to weigh some of the feeding ports. At present, through the improvement of lengthening the tail of the belt scale, changing the groove type idler to flat type idler, shortening the distance between idlers and moving the weighing position back, the weighing accuracy of the petroleum coke batching scale is below 3%.

1.2. Adjust the negative pressure system of the retort furnace

Negative pressure is the basis for the temperature control of the retort furnace fire channel. The negative pressure system of the retort furnace is adjusted from the large negative pressure operation to the small negative pressure operation, and the retort furnace fire channel is realized by adjusting the amount of calcined coke back. The temperature is controlled more stably, and the calcined coke discharge amount reaches 105kg/h·can.

1.3. Improve the feeding method of collected dust powder of calcined coke

The ash discharge chute leading to the center of each bin is installed at the ash discharge port of the dust collector, and the dust collected in the calcined bin is uniformly discharged with the calcined coke to achieve stable coarse and fine particle size of the calcined coke.

2. Molding process optimization

2.1. Stable ball mill purity

The purity and dosage of the ball mill powder directly affect the particle size distribution of the dry material in the formula and the amount of coal tar pitch, so stabilizing the purity of the ball mill powder is the core of the stable material. By adjusting the amount of fine coke added, the amount of collected dust powder, the supplementary method of steel balls, the opening of the damper and the speed of the classifier, the purity of the ball mill powder is maintained at 60-65%.

2.2. Improve the production formula

The production formula is the core of the raw anode production process, and its basic principle is to make the mixed material reach the best close-packed state, so that the raw anode can obtain the best internal structure and physical and chemical properties. On the basis of referring to the production formulas of other manufacturers and the adjustment experience of previous production formulas, strengthen the control of the particle size, focusing on stabilizing the +8 and +5 particle sizes, and reducing the 2-0mm particle size to less than 30%.

2.3. Optimizing the kneading molding process

Before the process improvement, a scale conveyor was used to transport the kneaded paste. The paste showed the characteristics of large heat dissipation and large internal and external differences. For this reason, the kneading molding process was greatly adjusted. The following kneading molding process was confirmed: the dry mixing temperature was 95-105°C, the wet mixing temperature was 160-164°C, the kneading time was 28-30 minutes, and the molding temperature was 148-155°C.

3. Optimization of baking process

3.1. Adjust the baking operation mode

In order to make the baking effect of the pre-baked anode more homogeneous, reduce the heating rate of the anode and prolong the high temperature time of the anode, the six-chamber operation mode is adjusted to the six-chamber semi-operation mode.

3.2. Optimize the baking process of the turning furnace chamber

When the smoke exhaust rack is in the 70# and 71# furnace chambers, increase the negative pressure to 170pa, let the volatile matter move forward, and move the smoke exhaust rack when the temperature reaches 600 °C, which can make full use of the heat of the flue gas to preheat the next furnace chamber . When the smoke exhaust rack stays in the 72# furnace room for 20 hours, the smoke exhaust rack is moved to the connecting flue of the 1# furnace room, and the connected flue is preheated. Determine whether to move the furnace to the next furnace chamber by observing whether the temperature of the smoke exhaust rack reaches 260 °C.

The movement of the combustion rack is based on 4P. When 4P is in the 67# furnace room, it needs to be moved 4 hours in advance to the 68# furnace room, 2 hours in advance when it is moved to the 69# furnace room, and it does not need to be moved to the 70# furnace room in advance. The 71# furnace room needs to be moved 4 hours in advance, the 72# furnace room needs to be moved 2 hours in advance, the 1# furnace room does not need to be moved in advance, and the burning rack can be moved to 1# in advance 12 hours.

When the combustion frame of the 1# furnace chamber is 6P, when the furnace is moved forward, on the basis of the specified time for moving the furnace, the furnace is pressed for 6 hours and the furnace is moved later. The total time is that the combustion frame stays at 1# for more than 18 hours. When the burner is in the 72# furnace chamber, the target temperature of the burner should be lowered from 1150°C to 1120°C.

Through the above method of moving the furnace, the combustion of volatile matter is two holes earlier than before, the temperature of the 4P product in the 1# furnace chamber is increased from 400 °C to 490 °C, and the final temperature of the anode is increased from 1000 °C to 1050 °C.

Practice has shown that by strictly controlling the quality of raw materials and optimizing the key process technologies of calcining, forming and roasting in the production process of prebaked anodes, the appearance qualification rate of green anodes has been increased from 62.1% to 98%, and the appearance qualification rate of anodes has increased from 89.6% to 89.6%. 99%, the anode primary rate was increased from 13.7% to 48%, and the quality of prebaked anodes was significantly improved.