Preparation method of aluminum fluoride for aluminum electrolytic cell

Abstract

The invention relates to a preparation method of aluminum fluoride for an aluminum electrolytic cell. The preparation method comprises the following steps of adding alkali into a lithium, aluminum andpotassium-enriched electrolyte leaching solution to adjust the PH; controlling proportion of Al3<+>, F<-> and OH<-> to carry out a precipitin reaction to obtain a certain amount of precipitate, wherein the reaction temperature is 20-110 DEG C and the reaction time is 20-120 min; and calcining the obtained precipitated product for 1-3 hours at 350-650 DEG C to obtain anhydrous aluminum chloride. By adding alkali and controlling the proportion of Al3<+>, F<-> and OH<-> to obtain hydroxyl aluminum fluoride and calcining the hydroxyl aluminum fluoride to obtain aluminum fluoride, more than 90wt%of Al3<+> and F<-> can be recovered simultaneously to the highest extent. In the process, other impurities are not introduced, and the alkali metal loss rate is low. The preparation method is simple to operate, makes preparation for follow-up lithium precipitation and is low in treatment cost.

Description

Technical field [0001] The invention relates to a method for preparing aluminum fluoride for aluminum electrolytic cells, and belongs to the field of metallurgy. Background technique [0002] my country’s bauxite is mainly distributed in Shanxi, Henan, Guangxi, Guizhou and other places. Alumina is produced from bauxite. As an important raw material for electrolytic aluminum, the consumption of alumina is increasing. my country’s original small high-quality bauxite The mine is nearly exhausted, and most companies have to mine and use a large amount of low- and medium-quality bauxite to produce alumina. However, alumina produced from low- and medium-quality bauxite contains many impurity elements, such as Li and K. The lithium content of the alumina produced in many regions exceeds 0.03%. Generally speaking, the alumina content of more than 0.03% is called lithium-rich alumina. According to relevant investigations and studies, the domestic lithium-rich alumina production accounts f...

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Problems solved by technology

[0003] For the recycling of waste lithium-rich potassium-aluminum electrolytes, Chinese patent specification CN105293536A chose inorganic acid leaching during the treatment process, Chinese patent specification CN105543504B chose roasting pretreatment before inorganic acid leaching, and patent 201910609881X chose heat treatment before inorganic acid leaching Salt leaching, the leaching solution is then directly used for lithium precipitation after removal of impurities. However, these leaching solutions contain a large amount of Al and F resources and have not been recycled. If they are not treated effectively, it will not only lead to waste of resources, but also affect The next step in lithium sinking

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