Method for preparing magnesium-based flame retardant from magnesium-containing wastewater

Abstract

The invention discloses a method for preparing a magnesium-based flame retardant from magnesium-containing wastewater, which comprises the following steps: (1) adding an aluminum-containing compound into Grignard magnesium-containing wastewater, sufficiently stirring to react for 0.5-3 hour, lowering the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering insoluble substances for the next batch of reaction; (2) supplementing and adding soluble aluminum salt according to a certain proportion to enable the amount of substance of aluminum ions to be 1 / 4-1 / 2 of the amount of substance of magnesium ions, and stirring and dissolving to obtain a mixed solution A of magnesium-aluminum metal salt; (3) preparing an alkaline mixed solution B from sodium hydroxide and sodium carbonate according to a certain ratio; and (4) quickly mixing and co-precipitating the two solutions A and B to obtain magnesium-aluminum composite hydroxide slurry, crystallizing for 3-36 hours at the temperature of 60-100 DEG C, centrifugally filtering, washing and drying to obtain the magnesium-based flame retardant. According to the method, magnesium resources in the Grignard magnesium-containing wastewater are fully utilized, and the obtained magnesium-based flame retardant has wide application, has the advantages of environmental friendliness, comprehensive utilization of resources and the like, and has a good industrial prospect.

Description

technical field [0001] The invention belongs to the field of resource utilization of waste water, specifically relates to the comprehensive utilization of magnesium resources in waste water containing magnesium, and in particular provides a method for preparing magnesium-based flame retardants by using waste water containing magnesium. Background technique [0002] Grignard reaction is widely used in the synthesis of high value-added products such as medicine, spices, and special silicone monomers. During the Grignard reaction process, a large amount of magnesium-containing wastewater will be formed. The wastewater has a strong acidity, and dumping it anywhere will cause environmental pollution. A large amount of dumping will affect the acidity and alkalinity of the soil, change the soil quality, and the water quality will also change greatly. The waste water has high salt content, and at the same time dissolves some organic matter, has high COD content, low biodegradability...

AI Technical Summary

Problems solved by technology

CN200410073583 discloses the recovery of magnesium ions by generating magnesium sulfate. This recovery process needs to concentrate a large amount of waste water, and then add concentrated sulfuric acid to generate magnesium sulfate, which requires higher energy consumption. At the same time, concentrated sulfuric acid causes serious corrosion to equipment.

CN101130485 discloses the recovery of magnesium ions by generating magnesium chloride. Magnesium chloride is a water-soluble salt, and the waste water needs to be evaporated to dryness. The energy consumption is high. At the same time, the obtained magnesium chloride often contains organic impurities, and its use is limited because of its low purity.

CN101665258 discloses a process for recovering magnesium salts from Grignard wastewater. First, alkali metal hydroxide is used to adjust the pH value of wastewater, and then carbonate is added for precipitation to obtain basic magnesium carbonate, which avoids the formation of magnesium hydroxide by direct precipitation. The solid-liquid separation problem of colloidal precipitation is difficult. The alkali consumption of this process is large, the salt concentration in the wastewater after magnesium extraction has not decreased, and the difficulty of wastewater treatment has not changed. At the same time, the practical application of the basic magnesium carbonate obtained is not wide

[0004] Judging from the research results of existing reports, the focus is on how to precipitate magnesium ions or evaporate to dryness to obtain crude magnesium salts, without fully considering the final use and product value of the obtained products, which has little practical significance