Method for preparing high-purity magnesium oxide with serpentine as raw material

Abstract

The invention relates to a method for preparing high-purity magnesium oxide with serpentine as a raw material. The method specifically comprises the steps that: (1) serpentine is crushed, and is activated by calcining; (2) 50wt% of hydrochloric acid is added to the calcined and activated mineral powder for carrying out acid leaching; heating, refluxing, and stirring are carried out; pump filtration is carried out, and a filtrate is collected; (3) ammonium bicarbonate is added and a pH value is regulated to 8-9; the mixture is settled and aged for 10-30min; pump filtration is carried out, and filtrate is collected; and (4) ammonium bicarbonate is continued to be added into the filtrate, until no precipitate is formed; a reaction is carried out under a temperature of 10-30 DEG C, such that basic magnesium carbonate can be obtained; bake-drying and pyrolysis are carried out, such that high-purity magnesium oxide is obtained. The method provided by the invention has the advantages of simple process, low cost, and suitability for industrialized productions. With the calcining activation method, difficulty for removing iron ions and a small amount of calcium component from a high-content magnesium salt of a traditional chemical purification method is solved. Leaching rate of magnesium oxide in serpentine can be higher than 93.53%, and magnesium oxide purity can be higher than 99.78wt%.

Description

technical field [0001] The invention relates to a preparation method of magnesium oxide, in particular to a method for preparing high-purity magnesium oxide by using antigorite as a raw material. Background technique [0002] Serpentine is an alteration product of olivine, which is a general term for a hydrous magnesium-rich silicate mineral with the general formula Mg 3 Si 2 o 5 (OH) 4 , whose structure is a 1:1 layered silicate mineral composed of silicon-oxygen tetrahedron and magnesium hydroxide octahedron. According to the shape of its internal structural layer, it is divided into lizardite, antigorite and chrysotile. The content of magnesium oxide in antigorite is generally more than 36%, and antigorite mineral resources in my country are very rich. The discovered mining areas include Jiangsu Donghai, Anhui Xiexian, Hubei Yichang, etc., and each mining area has an antigorite reserve. Both are above 500 million tons. [0003] As an important inorganic chemical prod...

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Problems solved by technology

[0006] Chinese patent 88109734.9 proposes a method for producing magnesium carbonate / or magnesium oxide and porous silicon dioxide using serpentine as a raw material. The method is first calcined at 400-800°C for 2-4 hours, and then treated with inorganic acid for separation. This patent considers the possibility of efficiently recovering magnesium from serpentine magnesium-containing leaching solution, but these processes do not consider the leaching rate of magnesium enough, especially under simple normal temperature and pressure, it is difficult to leach valuable metals in silicates. It will inevitably lead to unsatisfactory leaching effect of target metals such as magnesium. In this patent, Mg 2+ The leaching rate can only reach more than 85%, and the above-mentioned patent uses sulfuric acid as a solvent for extraction, which will generate calcium sulfate precipitates, resulting in incomplete decomposition of mineral powder, and the formed silica gel is also difficult to separate

[0007] Chinese patent 89106821.X proposes a comprehensive utilization process of serpentine tailings. In the process of neutralization, milk of lime is used as a neutralizing agent, which allows a large amount of calcium oxide to be mixed into the magnesium chloride solution while removing iron. Ca in MgO 2+ Content is one of the most important indicators to measure product quality, and in the carbonization process, this method is the same as the traditional dolomite method to produce magnesium oxide, using CO 2 In the two-step method, it has been proved impossible to completely separate calcium and magnesium in the carbonization process. In addition, this method has a long process, low recovery rate, and serious pollution of chloride ions washed away.

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