SU1671719A1 - Electrolyte for refining aluminium - Google Patents

Abstract

This invention relates to non-ferrous electrometallurgy, in particular to the production of high-purity aluminum. The goal is to improve the quality of the aluminum produced by reducing the sodium content in it. In the process of refining aluminum, an electrolyte of the following composition is used, wt%: potassium chloride 13–27, barium chloride 65–85, aluminum fluoride 2–8. Table 1.

Description

The invention relates to electrometallurgy of non-ferrous metals, in particular to the production of high-purity aluminum.

The purpose of the invention is to improve the quality of the aluminum produced due to the reduction of its sodium content.

In the electrolyte for refining aluminum, which includes barium chloride and aluminum fluoride, potassium chloride is additionally introduced at the content of components, wt.%:

Potassium Chloride 13-27

Barium chloride 65-85

Aluminum Fluoride 2-8

The density of the proposed melts is in the range of 2.45-2.6 g / cm3, ie, it meets the requirements imposed on electrolytes for the three-layer method: heavy refined aluminum and lighter than the anode alloy; therefore, the process does not undergo any changes. The absence of sodium ions in the melt ensures the purity of the resulting aluminum. The greater potassium excretion potential and its lower solubility in aluminum are

compared with sodium, it produces aluminum of the required purity for potassium.

At present, HF aluminum contains on average about 0.003 wt.% Sodium, which does not satisfy the foundry process. Experimental testing of the proposed electrolyte with the existing process parameters shows the absence of sodium and traces of potassium in the final product. Replacing expensive fluorides with cheap potassium chloride, as well as lower (more than 2 times) concentration of aluminum fluoride in the electrolyte, reduces the cost of melt and the intensity of its hydrolysis, which leads to a decrease in electrolyte consumption.

The lower limit of barium chloride content, as well as the upper limits of aluminum fluoride and potassium chloride, are determined by the melt density: it is less than 2.45 g / cm, which makes it impossible to use such melts for three-layer refining. The upper limit of the concentration of barium chloride and, respectively /

WITH

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Specifically, the lower limits of potassium chloride and aluminum fluoride are determined by the onset temperature of melt crystallization in this case exceeds 800 ° C, which also makes it difficult to use them for three-layer refining.

The limits of the change in the content of electrolyte components are selected on the basis of the experimental results obtained and are given in the table.

The sodium content of refined aluminum is less than 10%. and potassium 1-5G4 -1 (G%.

The lower limit of the concentration of aluminum fluoride is also determined by the need to ensure high-grade aluminum by impurities of iron, silicon, etc. This is explained by the possibility of their anodic dissolution with technological parameters of the refining process at a concentration of aluminum fluoride of 2 wt.%.

Claims (1)

The economic efficiency of the proposed solution is determined by the difference in prices for the components of the electrolyte and the reduction of their consumption. Only the replacement of sodium fluoride with potassium chloride at the same consumption (4 kg / ton of aluminum) gives an economic effect in the amount of 1.1 rubles / ton of aluminum. Electrolyte for aluminum refining using a three-layer method containing barium chloride and aluminum fluoride, characterized in that, in order to improve the quality of aluminum produced by reducing its sodium content, reducing its cost, it additionally contains potassium chloride at the next component content, wt.%: Potassium Chloride 13-27 Barium chloride 65-85 Aluminum Fluoride 2-8