Method for producing ultra-high purity aluminium sulfate from fly ash

Abstract

The invention discloses a method for producing ultra-high purity aluminium sulfate from fly ash, which comprises the following steps: mechanically activating fly ash, decarbonizing by floatation, removing iron by magnetic separation, extracting aluminium with sulfuric acid, separating solids from liquid, removing iron by resin adsorption, concentrating the low-iron aluminium sulfate solution, washing acid by alcoholization with organic alcohol, and dehydrating and drying the aluminium sulfate to obtain the ultra-high purity aluminium sulfate in which the content of Fe is lower than 0.2ppm. The ultra-high purity aluminium sulfate is better than the strictest technical requirements for Solid Type II First-Grade (low-iron product) and Solid Type III (high-aluminium low-iron fine product) in HG / T2225-2001 Industrial Aluminium Sulfate and Class I Solid (for drinking water) in HG2227-2004 Water Treatment Agent-Aluminium Sulfate. The invention has the advantages of simple technique, short procedure, easily controlled production process, high aluminium extraction yield, low production cost, low impurity content in the product and stable product quality.

Description

technical field [0001] The present invention relates to the process method of recycling and comprehensive utilization of fly ash, in particular to a method for producing ultra-high-purity aluminum sulfate from fly ash. After the liquid is separated, it is passed through a cation exchange resin to absorb and remove iron, and an ultra-high-purity aluminum sulfate with a Fe content of less than 0.2ppm can be prepared. Background technique [0002] Fly ash is a medium-grade aluminum ore rich in aluminosilicates, and with the continuous depletion of bauxite resources in my country, the use of fly ash to extract aluminum has a very broad application prospect. Aluminum salt is an important chemical raw material with a wide range of uses. Among them, aluminum sulfate and aluminum chloride are mainly used for drinking water, industrial water, wastewater and sewage treatment, papermaking, printing and dyeing, leather tanning, and can also be used as fire-fighting materials and their w...

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Problems solved by technology

In the aforementioned patent application for hydrochloric acid leaching extraction, since the concentration of hydrochloric acid solution cannot be very high, generally only 20% to 30%, a large amount of extra water needs to be consumed, and hydrochloric acid is easy to volatilize, causing hydrogen chloride gas to leak. , hydrochloric acid has a large corrosion effect on metal equipment, thus limiting the popularization and application of this technology

[0004] China Invention Patent Application No. 94100813.4 adopts the sulfuric acid acid leaching method to extract aluminum sulfate, and discloses a method for producing aluminum sulfate using fly ash as raw material, using fly ash as raw material, adding 50% to 60% sulfuric acid, and soaking for 12 to 24 hours , heated at 100°C for 2 to 4 hours, filtered while it was hot, washed the filter cake repeatedly to be neutral, combined the filtrates, boiled and concentrated to 15 to 20 Baume degrees, and filtered with suction to obtain aluminum sulfate crystals. The raw materials are easy to obtain and the process is simple. Low cost and other characteristics, but because the original fly ash did not remove iron, and the acid leaching solution did not take effective iron removal measures, resulting in high impurity components in aluminum sulfate products, and product use is limited

200810011311.2 discloses a method for preparing aluminum sulfate using fly ash, including the following steps: mechanical activation, sulfuric acid heating and pressure leaching reaction, generation of basic aluminum sulfate, adding sulfuric acid to the basic aluminum sulfate liquid, converting into aluminum sulfate solution, evaporation Concentration, cooling and crystallization to obtain aluminum sulfate crystals, the patent application for this invention aims to improve the extraction rate of aluminum, which involves the complex process of forming the intermediate basic aluminum sulfate, and the obtained aluminum sulfate crystals contain more impurities. It is difficult to prepare ultra-high-purity aluminum sulfate products, and the popularization and application are limited

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