Continuous preparation method of high-purity magnesium hydroxide

Abstract

The invention provides a method for continuously preparing highly pure magnesium hydroxide which relates to a method for continuously producing highly pure magnesium hydroxide with bischofite as raw material and ammonia as precipitant. The method is characterized in that: a treated bischofite is prepared into a solution with the concentration of 0.5 mol / L-4 mol / L, the bischofite solution and ammonia gas are added continuously after the reaction begins and the chemical reaction for depositing the magnesium hydroxide is carried out continuously. Characteristics of the reaction vessel utilization ratio, the productive capacity of unit volume, technical reliability and stability and so on of the method are greatly improved compared with intermittent reaction technology. The base liquid does not need to be replaced or heated repeatedly, thus energy-saving effect is distinct and labor productivity is high. The method can be used for obtaining magnesium hydroxide with the granularity of 10 microns-100 microns and the purity of 99 percent-99.999 percent. The ammonia nitrogen treatment of the tail solution adopts a commercial method that meets environmental protection requirement. The product produced by the invention has large granule size, high purity, more specifications, low cost, high equipment utilization rate and low one-time investment and has no pollution to the environment.

Description

technical field [0001] The invention belongs to the technical fields of metallurgy, inorganic non-metallic materials and chemical industry. Background technique [0002] At present, foreign countries use brine or seawater as raw material and milk of lime as precipitant to prepare magnesium hydroxide. There are domestic researches on using ammonia method to prepare magnesium hydroxide, but none of them can achieve continuous production, or the purity of the product cannot reach the technical requirements. standard. The magnesium hydroxide product of this technology has large particles, high purity, and continuous production process. So far, there has been no relevant literature report that has the two characteristics of high product purity and continuous production process. [0003] Now the commonly used process of using bischofite as raw material to prepare magnesium hydroxide is summarized as follows: [0004] (1) Lime brine method [0005] with MgCl 2 ·6H 2 O is the r...

AI Technical Summary

Problems solved by technology

The concentration of free ammonia in the reaction system is high, which is easy to cause environmental pollution

There are reports on the preparation process of high-purity magnesium hydroxide, but its production process is intermittent, that is, the production process is "configure the reaction bottom liquid - heat the bottom liquid - inject high-concentration magnesium chloride solution and ammonia gas - stop the injection process after reaching a certain capacity ——Filtration”, each batch of products needs to repeat the above process

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