Preparation method of high-purity magnesium oxide

Abstract

The invention belongs to the technical field of inorganic material preparation, and particularly relates to a preparation method of high-purity magnesium oxide. The method comprises the following steps: (1) preparing a magnesium chloride solution from magnesium chloride hexahydrate, and performing preheating; (2) performing centrifugal spray drying on the magnesium chloride solution at 650-750 DEGC to obtain anhydrous magnesium chloride powder; and (3) cooling the anhydrous magnesium chloride powder, putting the cooled powder into a heat-insulation rotary kiln, introducing excess water vapor,performing pyrolysis and cyclone separation to obtain the product magnesium oxide, and recovering tail gas to obtain hydrochloric acid. The method provided by the invention utilizes one-step dehydration of bischofite to produce the high-purity anhydrous magnesium chloride, and then utilizes the anhydrous magnesium chloride and the excess water vapor to prepare the magnesium oxide in the heat-insulation rotary kiln; and the method has the characteristics of a simple production process, a stable process, short production time, reduced energy consumption and production costs, and easy realization of industrialized scale-up production.

Description

technical field [0001] The invention belongs to the technical field of preparation of inorganic materials, and in particular relates to a preparation method of high-purity magnesium oxide. Background technique [0002] Magnesium oxide is an inorganic chemical product with important industrial uses in magnesium salt products. The higher the purity of magnesium oxide, the less impurity content, the better the performance. Excellent performance includes ultra-high melting point, good magnetic permeability and Excellent insulation performance and other physical properties, as well as specific chemical properties, are widely used in metallurgy, industrial catalysis, ceramics, construction, military industry, medicine, plastics and rubber and other fields. [0003] At present, most of the domestically produced magnesia is a common chemical raw material, and most of the high-purity and ultra-fine magnesia depends on imports. Therefore, the research on high-purity and ultra-fine mag...

AI Technical Summary

Problems solved by technology

[0005] Magnesium oxide is prepared by calcination of solid ore magnesite. This method has simple process and low cost, but the product has high impurity content and is difficult to remove, and will produce a large amount of carbon dioxide, which will pollute the environment. In the environmentally friendly 21st century, this method will face greater challenges

[0006] Magnesium oxide is prepared by precipitation method, which is rich in salt lake magnesium resources in my country. Precipitants such as soda ash, ammonia, ammonium bicarbonate, milk of lime, etc. are added to liquid magnesium resources such as salt lake brine and seawater to form magnesium ions in concentrated brine and seawater. The reaction forms magnesium carbonate, magnesium bicarbonate, magnesium hydroxide and other precipitated magnesium salts, and then calcined under certain conditions to obtain magnesium oxide products. The common point of the precipitation method is that chemical precipitants need to be consumed during the production process, so the process is relatively Complicated, relatively high production cost, but the process equipment of the precipitation method is relatively complicated, and the investment cost is high

Moreover, the utilization rate of the magnesium element in the brine raw material solution is not complete, and the chlorine element is transferred to a large amount of solid by-products of low value.

[0007] The direct pyrolysis method of brine is to place brine or bischofite in the air and heat it to a high temperature to undergo a thermal decomposition reaction to generate magnesium oxide products. However, due to the high-temperature hydrochloric acid gas produced by pyrolysis is highly corrosive, it requires high equipment and increases Reduced investment in equipment, limiting the promotion of the application

So far, there is still no pyrolysis device for the pyrolysis process of magnesium chloride, low energy consumption, large-scale, continuous pyrolysis production