Separation recycling method for aluminum electrolysis refractory electrolyte

Abstract

The invention discloses a separation recycling method for an aluminum electrolysis refractory electrolyte. The method includes the following steps that (1) the aluminum electrolysis refractory electrolyte is levigated and constituents are analyzed; (2) a sulfuric acid solution is prepared; (3) powder and the sulfuric acid solution are reacted at the temperature of 100-300 DEG C, gas is exhausted out and a solid material residues; (4) the solid material is cooled and dissolved with water; (5) filtering is performed; (6) when LiF and KF are not contained, Al(OH)3 precipitated from NaOH is added;(7) after Ca(OH)2 and Na2SO4 are added and reacted, filtering is performed; (8) when the LiF and the KF are contained, NaOH is added so that the pH value can reach 7-8, and then filtering is conducted after a Na2CO3 solution is added for reacting, or filtering is conducted after NaOH is added for reacting; and (9) mixed filter liquor is subjected to evaporation, concentration and filtration and raffinate is subjected to evaporation and dehydration. The separation recycling method is easy to operate, all useful constituents can be separated and resources can be fully recycled.

Description

technical field [0001] The invention relates to the technical field of separation and recovery of industrial aluminum electrolysis waste electrolytes, in particular to a method for separation and recovery of refractory electrolytes in aluminum electrolysis. Background technique [0002] In the process of industrial aluminum electrolysis production, an electrolyte with cryolite as the main component is used, and the main components of the electrolyte are NaF and AlF 3 Composition of cryolite, alumina and CaF 2 ; Some electrolytic aluminum plants in China also contain relatively high levels of LiF and KF in their electrolytes. [0003] Aluminum smelters in China contain two types of refractory electrolytes: one is the electrolyte with high carbon content that is fished out of the electrolyte melt in the electrolytic cell during the aluminum electrolysis production process, and is usually called "anode carbon slag" by the smelter ", this kind of anode carbon residue is called...

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Problems solved by technology

[0003] Aluminum smelters in China contain two types of refractory electrolytes: one is the electrolyte with high carbon content that is fished out of the electrolyte melt in the electrolytic cell during the aluminum electrolysis production process, and is usually called "anode carbon slag" by the smelter ", this kind of anode carbon residue is called "anode carbon residue containing lithium and potassium" according to whether the electrolyte contains high LiF and KF, but there is no LiF and KF or anode carbon residue with very little LiF and KF content It is called "lithium-free and potassium-free anode carbon slag"; because this electrolyte contains a relatively high content of carbon, generally 30-80%, it cannot be used, and it was often landfilled in the past, but this will cause environmental damage impact; now this treatment method has been banned, so the separation and recovery of anode carbon slag has become an important research topic at present; there are not many separation methods for anode carbon slag at present, and the existing flotation and combustion methods not only cannot The anode carbon slag can be effectively separated and recovered, and it will also cause new pollution; another difficult-to-handle electrolyte produced by industrial aluminum electrolytic cells is called a high-lithium and high-potassium electrolyte. In industrial aluminum electrolysis production, due to this electrolyte The content of LiF and KF in the aluminum alloy is too high, and the sum of the two accounts for more than 10% of the electrolyte components, which has a great negative impact on the production of aluminum electrolytic cells (it is not easy to generate a complete cell structure, and the current efficiency decreases ); At present, there is no effective treatment method to separate LiF and KF from the electrolyte component, resulting in more and more LiF and KF in the electrolyte component, so it can only be taken out from the electrolyzer, and then added with low Lithium-low-potassium electrolyte method is used to reduce the concentration of LiF and KF. There are more and more high-lithium-potassium electrolytes taken out of the electrolytic cell, but there is no way to deal with them, and they cannot be reused. Cause a lot of burden, also caused a waste of resources