A mechanochemical conversion and recovery method of sodium-containing and fluorine-containing compounds in aluminum electrolysis hazardous waste residue

Abstract

The invention relates to a method for mechanochemical conversion and recovery of sodium-containing and fluorine-containing compounds in aluminum electrolysis hazardous waste residue. The invention crushes, grinds and homogenizes the hazardous waste slag to obtain hazardous waste powder with particles ≤ 200 μm, and then adds hazardous waste powder, sodium compound and fluorine compound conversion agent, cyanide conversion agent, grinding aid and water to the conversion In the mill, the high-energy mechanical force acts synchronously on the mechanochemical conversion reaction of sodium-containing and fluorine-containing compounds, so that the sodium-containing compounds in the hazardous waste powder are transformed into soluble sodium compounds without fluorine, and the fluorine-containing compounds in the hazardous waste powder are transformed into Insoluble and harmless mineral fluorine compounds, cyanide compounds in hazardous waste powder are oxidized into harmless N 2 or NH 3 and CO 2 , so as to completely remove the hazards of fluoride and cyanide in the hazardous aluminum electrolytic waste residue, and realize the harmless and resourceful recycling of the hazardous aluminum electrolytic waste residue. The invention has the advantages of simple process, easy large-scale production, low production cost, no pollution of three wastes and environmental friendliness.

Description

technical field [0001] The invention relates to a method for mechanochemical conversion and recovery of sodium-containing and fluorine-containing compounds in aluminum electrolytic hazardous waste residue, and belongs to the technical field of harmless and resourceful utilization of solid waste in the electrolytic aluminum industry. Background technique [0002] By 2017, China has built about 45 million tons of aluminum electrolytic production capacity, and the actual output exceeds 36 million tons, accounting for more than 50% of the global electrolytic aluminum production capacity. Aluminum electrolytic cells generally need to be shut down for overhaul after 4 to 6 years of use, and all waste lining materials (referred to as overhaul slag) are taken out. Overhaul slag is an inevitable solid waste in the electrolytic aluminum production process. About 10-30kg of overhaul slag is discharged from the electrolytic production of 1 ton of primary aluminum. The overhaul slag of e...

AI Technical Summary

Problems solved by technology

[0042] The current wet treatment technology has at least the following main problems: first, a large amount of salty and fluorine-containing wastewater is not effectively treated, causing secondary pollution; the produced H 2 、CH 4 , NH 3 The gas is not controlled and utilized; the generated HF causes serious pollution

Second, the recovered electrolyte and carbon materials contain too many impurities and cannot be used directly

Third, the process route is cumbersome, the technology is complicated, the equipment is severely corroded, and the processing cost is too high

Fourth, due to factors such as the difference in capacity and age of the electrolytic cell in the hazardous waste residue of aluminum electrolysis, and fluctuations in composition, it is difficult to control the production process

[0043] The current fire treatment technology has at least the following main problems: First, the tail gas that produces a large amount of entrained HF and dust needs to be treated

Second, the recovery of electrolyte salt is not complete, and it needs further treatment if it remains in carbon materials or slag

Third, the electrolyte salt with a low melting point melts and agglomerates in the furnace, resulting in a large residual amount of incomplete oxidation and combustion of the carbon material. The melting and agglomeration in the furnace leads to deterioration of production conditions and poor production stability

Fourth, it is difficult for the reaction materials to achieve uniform mixing at the molecular level, resulting in incomplete conversion reactions

Fifth, the equipment is seriously corroded and the energy consumption is high

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