SU1752829A1 - Method of starting aluminium electrolyzer after overhaul - Google Patents

Abstract

Usage: electrolytic I aluminum production. SUMMARY OF THE INVENTION: A lumpy circulating electrolyte with a cryolite ratio of 2.9–3 and a calcium fluoride content of 3.5–4.8 wt.%, Washed down with a liquid electrolyte, is used as the starting raw material; the lumpy electrolyte is completely melted at elevated life, and then reduce it to the worker on schedule: 1 day, - 9-7, 2 days - 7-6, 3 days. - 6-5,8, 4 days, - 5.8-4, 5-8 days .- 5-4.8, 9 days, - 4.8-4.5 V. Using the proposed method allows to reduce start-up costs and improve the quality of aluminum powder in the post-launch period. 1 tab.

Description

The invention relates to non-ferrous metallurgy and can be used in the electrolytic production of technical aluminum.

The purpose of the invention is to reduce the cost of starting the Electrolyzer and improving the quality of the aluminum-fiber material in the post-launch period.

In the method of launching an aluminum electrolyzer after an overhaul, a solid refined circulating electrolyte is used as a starting material, having a cryol ratio of 2.9-3.0 and containing 3.5–4.8 wt.% Calcium fluoride, and the decrease in voltage up to the working schedule

1SUT9.0-7.0 V

2Sut7.0-6.0 V

3S6.0-5.8 V

4 days 5.8-5.0 V 5-8 days 5.0-4.8 V 9 days 4.8-4.5 V. The cryolite ratio of the circulating electrolyte used is 2.9-3.0 with calcium fluoride content of 3.5 - 4.8 wt.% Was chosen to ensure, during the post-launch period, an optimal 1 cryolite ratio of 2.7-2.8 and an optimal electrolyte composition, which ensures a return to the normal process conditions without additional adjustments of the electrolyte composition. The selected electric start-up mode ensures high grade of the metal in the post-launch period and reduces the time for the bath to return to normal operation.

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Example. A solid refined circulating electrolyte with a cryolite ratio of 2.9, calcium fluoride content of 4.8 wt.%, In an amount of 8.4 tons, is loaded on the periphery of the electrolyzer shaft. Then the bottom is heated and 7.1 tons of fresh liquid electrolyte is poured. A cell is connected and a voltage of 20 V is established until the electrolyte is completely melted in the bath. Thereafter, the voltage is reduced to 9 V and further to the operating voltage according to the graph above. The metal is poured during the first days after start-up and by the end of 5 days the metal mirror rises to 340-350 mm and the electrolyzer goes to normal operation. After 3 days after pouring aluminum take metal analysis. In the bath metal grade A6.

The data on pilot start-ups of electrolyzers during the development of the technology are given in the table.

An analysis of pilot launches shows that when using solid refined circulating electrolyte as a starting material, which has a krilite ratio of 2.9–3.0 and containing 3.5–4.8 wt.% Calcium fluoride, keep on schedule: 1 day9.0-7.0 V

2Sut7.0-6.0 V

3S6.0-5.8 V

0

4 days5.8-5.0 V

5-8 days 5.0-4.8 V 9 days 4.8-4.5 V,

the electrolytic cell reaches a more rapid output to the normal technological regime with the production of A5-A6 grade metal, the consumption of fluoride salts at the start is reduced.

Claims (1)

Invention Formula The method of starting an aluminum electrolysis cell after a major overhaul, including loading starting material into the mine, pouring molten electrolyte, electrically switching the electrolyzer to increased voltage and reducing it to the worker, and pouring liquid metal, characterized in that improvement of the quality of aluminum-raw material in the post-launch period; solid starting-up recycled electrolit is used as starting material; it has a cryolite ratio of 2.9-3.0 and contains 3.5-4.8 wt.% calcium fluoride, and a decrease in the voltage to the worker is kept on schedule: five 0 1 day 2 day 3 day 4 days 5,6,7,8 days 9 days. 9.0-7.0 V 7.0-6.0 V 6.0-5.8 V 5.8-5.0 V 5.0-4.8 V 4.8-4.5 V 8.5 2.9-3.0 4.5 6.8 8.5 2.9-3.0 4.5 6.8 8.5 2.8 4.5 6.8 8.5 8.5 8.5 2.9 4.5 6.8 9.0-7.0 7.0-6.0 6.0-5, 5.8-5.0 5.0-4.8 4.8-4.5 AO eight 2.9 4.5 6.9 9.0-7.0 7.0-5.0 5.0-4.8 4.8-4.5 - - AO 10 2.9 3.0 6.8 9.0-7.0 7.0-6.0 6.0-5.8 5.8-5.0 5.0-4.8 4.8-4.5 AO 12 The voltage rise is conducted at a speed of 5–10 V / h, the voltage is reduced in two stages: at the first at a speed of 5–10 V / h to 8–8.5 V, and at the second - at a speed of 0.3–5 0.5 V / h to voltage 4.0-4.4 V 9.0-7.0 7.0-6.0 6.0-5.8 5.8-5.0 5.0-4.8 4.8-4.5 AO 9 9.0-7.0 7.0-6.0 6.0-5, 5.8-5.0 5.0-4.8 4.8-4.5 AO eight 9.0-7.0 7.0-5.0 5.0-4.8 4.8-4.5 - - AO 10 9.0-7.0 7.0-6.0 6.0- 5.8 5.8-5.0 5.0-4.8 4.8-4.5 AO 12 In the process of entering the mode, the module is reduced to 2.6. Disrupted process mode See the peeling of coal blocks -J l N5 00 NJ CHO The electrolyte temperature rises. The day of the formation of a stable crown was required 8.5 2.9 5 Do not start up when the content of CaFg 5 wt.% Due to the danger of carbonization of the bath 3.1 U.5 6.8 9.0-7.0 7.0-6.0 6.0-5.8 5.8-5.0 5.0-4.8 4.874.5 AO 5 8.5 3.0 4.5 6.8 9.0-8.0 8.0-7.0 7.0-6.0 6.0-5.0 5.0-4.8 4.8 -4.5 AB Yu 8.5, 3.0 4.5 6.9 9.0-7.0 7.0-6.0 6.0-5, B 5.3-5.0 5.0-4.8 4, 8-4.5 A5 The electrolyte module at the exit to the mode decreases to 2 ,, 9. Elevated electrolyte temperature Power consumption increases, rubbing of fluoride salts Normal mode