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Magnesium Manufacturer: Introduction to the Preparation Process of High-Purity Magnesia
The preparation of high-purity magnesia involves using magnesium-containing compounds as raw materials; part of these are first calcined to produce light-burned magnesia, which is then further melted or re-calcined to obtain High-purity magnesia , a portion is directly calcined or pyrolyzed to obtain high-purity magnesium oxide.
What are the methods for preparing high-purity magnesia from magnesite?
I. Direct Calcination of Magnesite
This method can be divided into two-step calcination and one-step calcination. The second step of calcination employs high-quality magnesite. First, the material is subjected to preliminary calcination in a kiln, with the temperature controlled at around 1273 K, to produce lightly calcined magnesia. Subsequently, mechanical crushing and ball milling are carried out to eliminate the “pseudomorphosis” phenomenon during ball milling while minimizing the particle size of the magnesium oxide powder. The magnesium oxide powder is then sintered under controlled conditions to obtain the final product. This process features a wide range of raw material sources, a simple procedure, and low production costs. However, due to the difficulty in separating impurities present in magnesite, the purity of the resulting magnesium oxide typically struggles to exceed 99%; this limitation can be overcome by selecting higher-purity raw materials and optimizing impurity-removal techniques. Specifically, magnesite is mixed with graphite powder to form a lightly calcined magnesia powder, which is then uniformly blended with a rare-earth magnesium alloy and compacted into pellets before being sintered at high temperatures to yield high-purity magnesia. This process can produce high-purity magnesia with a purity exceeding 99.8% and a bulk density of at least 3.50 g/cm³.
Compared with the two-step calcination process, the one-step calcination eliminates the light-burning activation step and directly sinters high-purity magnesium oxide. One-step roasting of magnesite concentrate. High-purity magnesia , including a mixing and briquetting unit and a high-temperature calcination unit. After thorough mixing in the mixer, magnesite concentrate and binder are fed into a briquetting press to form high-density pellets, which are then subjected to one-step calcination in a high-temperature shaft kiln, yielding magnesium oxide with a purity of ≥97.5% and a bulk density of ≥3.20 g/cm³.
II. Magnesium Ammonium Leaching Method
Light-burned magnesium oxide obtained by calcining low-grade magnesite is reacted with an ammonium chloride solution, and the ammonia generated in the reaction is absorbed by pure water. After the reaction, impurities remain in the slag. Following separation of the liquid phase from the waste slag, the leachate can directly react with the recovered ammonia to form magnesium hydroxide, which is then converted into magnesium oxide through a two-step calcination process. In this process, the ammonium chloride mother liquor can be recycled. Using the ammonium leaching method, magnesium oxide with a MgO content of 99.97% and a density of 3.41 g/cm³ was obtained. Although this method yields magnesium oxide of high purity and excellent performance, the process design is lengthy and the operational management in actual production is challenging.
III. Magnesia Carbonization Method
Solid ores such as magnesite are calcined to form a powder, then digested and carbonated with carbon dioxide; the resulting basic magnesium carbonate precipitate is filtered and thermally decomposed, followed by dehydration and drying to yield light-grade magnesium carbonate, while further calcination produces light-grade magnesium oxide. The compacted green bodies, after dead-burned, yield High-purity magnesia High-purity magnesia with a purity of 99.21% and a bulk density of 3.38 g/cm³ was obtained via carbonization. The carbonization method offers several advantages, including strong selectivity, non-corrosiveness, high recovery rates, wide availability of raw materials, and ease of recycling.
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Henan Mingmei Magnesium Technology Co., Ltd.
Phone:+86-392-3658888 / 3659999
Email:hnmingmei@163.com
Address: Hebi National Economic and Technological Development Zone, Henan Province
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