Method for duplex deposition of high-purity magnesium hydroxide by liquid ammonia-ammonia

Abstract

The invention provides a method for depositing highly pure magnesium hydroxide with a liquid ammonia-ammonia twofold-gang and relates to a method for continuously producing the highly pure magnesium hydroxide with a bischofite as raw material and ammonia and ammonia water as a precipitant. The treated bischofite is prepared into a solution with the concentration of 0.5 mol / L-4 mol / L, the precipitant is supplied by ammonia gas at the early stage of the reaction, then the precipitant is provided by the ammonia water reclaimed from the decomposition of the reaction product, ammonium chloride, the ammonia gas supplements the rest amount and the reaction process can be carried out continuously or intermittently. The method can be used for producing the magnesium hydroxide with the granularity of 10 microns-100 microns and the purity of 99 percent-99.999 percent. The product, ammonium chloride, adopts alkaline splitting and vacuum ejection flow to reclaim the ammonia gas, prepare the ammonia water for recycling utilization. The product produced by the invention has large granule size, high purity, more specifications, low cost, high equipment utilization rate, high reliability and stability of the technique, 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. In China, ammonia method is used to prepare magnesium hydroxide, but these research works cannot realize 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 the continuous and intermittent production process can be randomly controlled. So far, no relevant literature reports with similar technical characteristics have been seen. [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 raw material ...

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

Images