Method for preparing aluminum oxide from aluminum ash in slag-free manner

Abstract

The invention discloses a method for preparing aluminum oxide from aluminum ash in a slag-free manner, which comprises the following steps: proportionally introducing chlorine into aluminum ash, controlling the reaction temperature and time, introducing water vapor after completing primary denitrification, removing residual nitrogen, fluorine and chlorine to obtain impurity-removed aluminum ash and adsorption steam, and condensing the adsorption steam to form an adsorption solution; adding a corresponding amount of lime into the adsorption solution, reacting to obtain a defluorination solution, adding SO2 for neutralization to obtain an ammonium sulfate solution, and concentrating the solution to obtain an ammonium sulfate product; adding alkali liquor at a corresponding proportion to conduct alkali dissolution treatment on the impurity-removed aluminum ash, thus preparing a liquid phase and a slag phase; and additionally mixing a Bayer process solution with an alkali solution, and carrying out seed crystal decomposition and roasting to obtain the aluminum oxide product. According to the method, a two-stage steam impurity removal mode is adopted, so that the removal efficiency of nitrogen in the aluminum ash is greatly improved, fluorine residues are effectively removed, the aluminum ash is subjected to impurity removal through alkali dissolution treatment, corrosion to equipment is small, and implementation is easy.

Description

technical field [0001] The invention belongs to the technical field of aluminum ash utilization, and in particular relates to a method for realizing harmless utilization of valuable components in aluminum ash by using steam pretreatment and alkali dissolution technology. Background technique [0002] Aluminum ash is one of the main wastes in the aluminum smelting process. Every ton of primary aluminum / aluminum material will produce 180~290kg of aluminum ash slag, and the annual discharge of millions of tons. Aluminum ash is included in the list of hazardous wastes due to nitrogen, fluorine, chlorine and other reasons. [0003] In recent years, relevant practitioners have carried out a lot of research work on the efficient and high-value utilization of aluminum ash, such as "A method for comprehensive utilization of waste aluminum ash and slag forming blocks, public number : CN109402672A "main steps include: (1) aluminum slag is mixed with binding agent, water and stirred to...

AI Technical Summary

Problems solved by technology

[0007] Although the existing methods can also realize the comprehensive utilization of aluminum ash, there are many problems such as complicated process and high energy consumption, and water immersion is often used in the pretreatment process, and the ammonia and fluorine-containing liquid phase produced enters with the water leaching slag. Subsequent process; if no pretreatment is carried out, nitrogen, fluorine, and chlorine will also affect the subsequent process