The modern aluminum industry uses cryolite-alumina melt electrolysis. The molten cryolite is a solvent, the alumina is used as a solute, the carbon body is used as a positive electrolytic aluminum electrode, and the aluminum liquid is used as a cathode. After a strong direct current is applied, the electricity is applied at two poles in the electrolytic cell at 950 ° C - 970 ° C. Chemical reaction, ie electrolysis. The anode product is mainly carbon dioxide and carbon monoxide gas, which contains a certain amount of harmful gases such as hydrogen fluoride and solid dust. In order to protect the environment and human health, the anode gas needs to be purified to remove harmful gases and dust and then discharged into the atmosphere. The cathode product is aluminum liquid, and the aluminum liquid is taken out from the tank by vacuum lifting bag, sent to the foundry workshop, purified and clarified in the holding furnace, cast into aluminum ingot or directly processed into a strand blank, a profile, and the like.
Aluminum electrolysis production can be divided into three categories: side-inserted anode rod self-baking tank, upper anode rod self-baking tank and prebaked anode tank.
The production of electrolytic aluminum from self-baking tank has the characteristics of simple equipment, short construction period and low investment, but it can not be treated by flue gas, serious pollution environment, difficult mechanization, high labor intensity, not easy to enlarge, low yield of single tank, etc. The shortcomings that have been overcome have been basically eliminated.
At present, most countries and production companies in the world are using large pre-baked tanks. The current intensity of the tank is very high, not only high degree of automation, low energy consumption, high single-slot production, but also meets the requirements of environmental regulations.
China has completed industrial trials and industrialization of modern pre-baked tanks of 180kA, 280kA and 320kA. The technology improvement and transformation centered on energy saving and environmental protection standards have promoted the conversion of self-baking production technology to pre-baked tanks, which has achieved great success.
According to the production process of electrolytic aluminum, the production cost of electrolytic aluminum is roughly composed of the following parts:
(1) Raw materials: alumina, cryolite, aluminum fluoride, additives (calcium fluoride, magnesium fluoride, etc.), anode materials;
(2) Energy costs: electricity (DC and AC), fuel oil;
(3) Labor costs: wages and other management fees;
(4) Other expenses: equipment loss and depreciation, financial expenses, transportation expenses, taxes, etc.
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