RU2556188C1 - Method for obtaining aluminium and silicon alloys in aluminium electrolysis units - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method involves preliminary processing of crushed aluminosilicate raw material containing the used bottom, alumina and electrolyte by mechanical activation both separately and mixed with alumina, periodic loading of the treated raw material to the electrolysis unit and electrolysis process of the melt with formation of silumin directly in an electrolyte bath.

EFFECT: high dilution speed of raw material; reduction of voltage and consumption of power and increase of service life of an electrolysis unit.

Description

The invention relates to non-ferrous metallurgy, and in particular to the production by electrolysis of aluminum-silicon alloys (silumins), widely used in industry.

The method is well known [Tabereaux A.T., Ms. Mihn C.J., Production of aluminum-silicon alloys from sand clay in Hall cells. Light Metals, 1978, p.209-222], according to which sand (silica, SiO ₂ ) is loaded into the electrolyzer producing aluminum, simultaneously with the main raw material - alumina. Using this technology, the dissolution of alumina and especially silica occurs very slowly, accompanied by the appearance of a precipitate on the bottom of the electrolyzer and, consequently, an increase in heating voltage, electrolysis temperature, increased energy consumption and, as an additional consequence, a decrease in the service life of aluminum electrolysis cells.

The closest in technical data is the method of producing alloys by dissolving the mullites that are part of the waste hearth of aluminum electrolyzers [BJ⌀rn Moxnesl, Håvard Giklingl, Halvor Kvande2, Sverre Rolseth3 and Kjetil Straumsheiml. ADDITION OF REFRACTORIES FROM SPENT POTLINING TO ALTIN Al-Si ALLOYS, Light Metals 2003 Edited by Paul N. Crepeau TMS (The Minerals, Metals & Materials Society), 2003]. The authors loaded the ground powder of spent hearth together with alumina powder into an industrial electrolyzer. On the electrolyzer with a current strength of 115 kA, the loading of the spent electrolyte powder containing mullite was accompanied by:

1. The formation of sediment on the bottom.

2. By raising the temperature to 1000 ° C.

3. The need to reduce current strength and, therefore, performance.

4. According to the proposed method, the feedstock containing silicon oxides is subjected to preliminary mechanical activation in order to reduce grain sizes to 10-20 microns and create a crystalline or pseudocrystalline structure containing defects. The chemical potential of such silica is significantly higher. The high chemical potential of SiO ₂ accelerates the dissolution process, as is well known in chemical technology.

The technical result of the invention is to change the conditions for the production of aluminum-silicon alloys, in which silicon oxide or compounds containing silicon oxide, for example mullite (3Al ₂ O ₃ · 2SiO ₂ ), are subjected to preliminary treatment by mechanical activation, either separately or in a mixture with alumina, the main raw materials feeding the electrolyzer.

The claimed method differs from the prototype in that the acceleration of dissolution of the starting material is observed at an activation time of 5-60 seconds in a planetary mill with an energy ratio of 50 g. By visual observation, it was found that the dissolution rate increases by 2–3 times, and no precipitate appears.

These differences allow us to conclude that the proposed technical solution meets the criterion of "novelty." Signs that distinguish the claimed method from the prototype are not identified in other technical solutions in the study of this and related fields of chemistry and, therefore, provide the claimed solution with the criterion of "inventive step".

The technical result is achieved by the fact that in the method for producing aluminum-silicon alloys in aluminum electrolysis cells, it is new that in order to increase the dissolution rate of the initial aluminosilicate raw material, the initial product is subjected to mechanical activation with parameters: grain size 10-30 μm, activation time 5-60 s , power ratio of the mill 20-50 g. Also new is that only the silicate part of the charge loaded into the bath is subjected to mechanical activation, and a charge mixture containing alumina and silicon-containing raw materials is used as mechanical activation, using silica, for example, pure sand, or the silicate part of the bottom of aluminum electrolysis cells.

The invention consists in a method for producing aluminum-silicon alloys by preparing raw materials (alumina-silica mixture) followed by electrolysis in industrial aluminum electrolyzers of cryolite-aluminosilicate melts.

Preparation of raw materials by mechanical activation in a certain parametric mode of indicators (grain size of silicate material 5-25 μm, residence time in the mill 5-60 seconds, with an energy ratio of the last 20-50 g) provides a dissolution rate 2-3 times higher than in the mode used in the prototype. The use of mechanical activation, a new technology for the preparation of silicate raw materials will provide a high rate of its dissolution, lower voltage and energy consumption, and a longer battery life.

Claims (1)

A method of producing aluminum-silicon alloys in an aluminum electrolysis cell, comprising preparing a charge mixture containing aluminosilicate raw materials, including spent hearth and spent electrolyte of an aluminum electrolyzer and alumina, loading a charge mixture into an electrolyzer followed by electrolysis in molten electrolyte in an aluminum electrolysis cell, characterized in that preparation of the charge mixture is carried out by mechanically activating it in a mill with an energy ratio of 20-50 g and a grain size of 10-30 m km at an activation time of 5-60 s.