Study On Aluminum Electrolysis "Two Decreasing And One Saving" And Its Realtive Technology Applications

By the influence of international financial crisis and continuously rising of the electrovalence, it is predicted that the development of domestic aluminium electrolysis industry will face the huge challenges in the future. One of the key measures to make the domestic aluminium electrolysis companies get out of the trouble and realize the sustainable development is to implement energy saving and emission reduction and reduce the production cost. Meanwhile, with the subsidizing of national support project "low temperature and low voltage aluminum electrolytic new process", this text carries out the study of "two decreasing and one saving" technology, which tests with5cells and centres on reducing the cells’voltage and saving anode carbon consumption for technology breakthrough so as to get the aluminum electrolysis energy conservation and emission reduction technology. The main research results of this paper are as follows:(1)To improve the furnace construction process control of the test cells, and strict process management mainly in aspects of material quality, cathode carbon assembly,paste temperature,air pressure, paste adding amount, carbon paste tamping,which can guarantee the carbon steel pressure drop not exceeding55mv when going on the400A current test for the assembled cathode carbon by the DC welding machine and make sure the uniform current distribution of the cells after the baking start, without biascurrent, so as to avoid the problems such as the stub melting and anode falling out etc.(2)By the reasonable cell baking start and final-period management, optimizing the technical condition match, fixing the aluminium level by hearth and aluminium level and voltage relationship and improving the employee’s technical skill to avoid the alumina sediment inside the cells by personal factors. After the test cells run one year, the hearth pressure drop can realize300mv and is lower54mv than the contrast cells.(3) He precondition of the short cathode and anode distance production is steady cell conditions, and fixes the best electrolysis tempreture and aluminium level to realize the regulation and control for the test cells’stability by hearth, aluminium level and voltage. After one year’s groping for the test cells, the best match process technical conditions are found:the cells’temperature should be between930-945℃, the set voltage of cells should be3.8v, the average voltage can drop down to3.85v and the measured average cathode and anode distance should be4.05cm.(4)The modified anode improves greatly the physics and chemistry indexes of prebake carbon, the most obviously is resistivity of the test cells is lower15-35μΩ.m than contrast cells, the volume density higher0.15-0.20g/cm3, air reaction residue loss higher8.9%, CO2reaction residue higher10.9%, porosity lower than8%. The average anode voltage drop of the test cells is106mv and is lower46mv than contrast cells. The anode service cycle time can be extended to36days and is longer8days than normal anode. The operate cathode and anode exchange workload can reduce25%, and the average gross anode consumption is416kg/t-Al.(5)The material and energy balance is not only the basis of the normal aluminium electrolysis production, but also mutually relate and influence with other indexes. The carbon loss rate of the test cells is0.77kg/h and is lower2.48kg/h than the contrast cells. The aluminium fluoride consumption of the test cells is0.26kg/h and is lower0.176kg/h than the contrast cells. The electrical energy efficiency of the test cells is51.1%and is higher4.28%than the contrast cells.