A method for preparing aluminum hydroxide by using ammonia water to decompose fly ash dissolution liquid

Abstract

Relating to the aluminum hydroxide production field, the invention specifically discloses a method of decomposing a fly ash dissolution solution by ammonia water to prepare aluminum hydroxide. The method includes: subjecting fly ash to ammonia process roasting, dissolving the product in water at 50-95DEG C and performing separation so as t o obtain an aluminum sulfate solution containing iron ions; removing the iron ions from the solution by a cation exchange resin technique to obtain an aluminum sulfate refined solution; absorbing the roasting generated ammonia with water to obtain ammonia water for decomposition of the iron removed aluminum sulfate solution, firstly using ammonia water to adjust the pH of an early stage solution, then adding a seed crystal to adjust the pH of a second-stage solution, and finally adjusting the end point pH value; and remaining the state for certain time, thus obtaining aluminum hydroxide with a large particle size. The method provided by the invention adopts the ammonia water obtained by absorption of ammonia produced in the roasting process to decompose the iron removed solution, the pH of the solution is easy to control, the aluminum hydroxide produced by decomposition is easy to realize solid-liquid separation, and the process is simple and is in favor of industrialization.

Description

technical field [0001] The invention belongs to the field of aluminum hydroxide production, in particular to a method for preparing aluminum hydroxide by using ammonia water to decompose fly ash dissolution liquid. Background technique [0002] Fly ash is a solid waste from coal-fired power plants. At present, my country's annual discharge of fly ash is hundreds of millions of tons, and the total stockpiles of fly ash in my country are more than one billion tons. The discharge of a large amount of fly ash not only occupies a large amount of land, but also seriously pollutes the environment, which constitutes a double damage to the ecology and the environment. Therefore, the comprehensive utilization of fly ash has great practical and long-term strategic significance. Similarly, my country is a country that is not rich in aluminum resources, and bauxite can no longer meet the future demand for minerals. According to the current growth rate of alumina production and the was...

AI Technical Summary

Problems solved by technology

There are also some problems in the extraction of alumina in fly ash by this alkaline method. The calcium silicate slag produced by the sintering method can only be used as cement raw materials, and the amount of slag produced is larger, which will cause more pollution; Coal ash equipment requires large investment, high energy consumption and high cost

At present, some enterprises adopt sulfuric acid method and hydrochloric acid method. These two methods require high corrosion resistance of equipment, large equipment investment, and poor reliability; while the preparation process of ammonium sulfate sintering method is a reduction process, and the amount of slag is small; The reaction system is a weak acid system, and the equipment is easier to solve, which is conducive to industrialization

Images