Process for preparing magnesium hydroxide whiskers and calcium sulfate from phosphorus tailings

Abstract

The invention discloses a process for preparing a magnesium hydroxide whisker and calcium sulfate by using phosphate tailings as raw materials. The process comprises the following steps: mixing phosphate tailings obtained through flotation with hydrochloric acid to react and obtaining a mixed solution containing magnesium chloride and calcium chloride after impurity removal and filtration; mixing the phosphate tailings with sulfuric acid to react and obtaining a magnesium sulfate solution after impurity removal and filtration; mixing the two solutions and obtaining a calcium sulfate precipitate and magnesium chloride filtrate after reaction and filtration; adding alkali liquor to the magnesium chloride filtrate and obtaining a liquid-solid mixture containing a basic magnesium chloride whisker after reaction and aging; adding an alkaline solution later and obtaining the magnesium hydroxide whisker after reaction and aging; returning ammonia gas recovered through gas stripping of the filtrate to the section for producing the magnesium hydroxide whisker and returning the liquid phase after gas stripping to the acidolysis section after the liquid phase is crystallized to remove ammonium chloride. The process has the beneficial effects that the phosphate tailings are used as the raw materials to produce the magnesium hydroxide whisker and the byproduct calcium sulfate, and meanwhile, higher value application of the phosphate chemical solid wastes and cleaner production are achieved by recycling surplus ammonia gas.

Description

technical field [0001] The invention belongs to the field of waste resource utilization and functional nanometer materials, and in particular relates to a process for producing magnesium hydroxide whiskers and calcium sulfate by using phosphorus tailings as raw materials. Background technique [0002] Phosphate rock is the main fertilizer needed for global agricultural production—the raw material of phosphate fertilizer, an important guarantee for global food production; it is also a raw material for the production of fine chemical products. More than 90% of the phosphate rock grade in my country is lower than 26%, with an average grade of about 17%. With the continuous mining and utilization of phosphate rock resources, the development and utilization of low-grade and refractory phosphate rock resources have attracted the attention of many researchers. The content of magnesium, iron and aluminum oxides in most low-grade ores in my country is high, and it needs to go throug...

AI Technical Summary

Problems solved by technology

[0012] The purpose of the present invention is to provide a process for producing magnesium hydroxide whiskers and calcium sulfate using phosphorus tailings as raw materials, effectively solving the comprehensive problems of phosphorus tailings accumulation and environmental pollution, and improving the comprehensive utilization rate of magnesium resources associated with phosphate rocks; The by-product calcium sulfate can be used for plaster bandages, making plaster models, chalk, handicrafts, etc. At the same time, the solid waste filtered out during the acid hydrolysis process can be used for building materials