The development of low iron fused magnesia

The development of low-iron fused magnesia strengthens the construction of magnesite ore supply bases

The magnesia refractory raw material industry is a typical resource-based industry. Since China's reform and opening up in the 1980s, the price of fused magnesite has increased rapidly due to the rapid increase in the demand for magnesia raw materials, and the low entry barriers for primary raw material processing have caused serious damage to the rational development of magnesite. Due to economic reasons, the price of the magnesite super ore is about 5 times that of the third grade ore. Extensive mining, the phenomenon of mining rich and abandoning poverty is serious, resulting in a great waste of resources, and more serious is the misalignment of mining and stripping. The author participated in the “point adjustment” of 12 key magnesite mines in Liaoning in 2005. It was estimated that the debts of rock stripping amounted to more than 100 million tons at that time. The situation has not fundamentally changed since then, which has caused difficulties in mining some high-quality ore. In recent years, special-grade mines in the original sense have been very rare, first-grade mines are in short supply, and the declining ore quality has caused the average MgO content of magnesia to drop by more than 0.5%. Light burnt magnesia powder manufacturer

Ramming material export for intermediate frequency furnace

Therefore, in order to use limited resources in a reasonable and effective manner, relevant laws and regulations must be carefully implemented. The magnesite mines and old mines with an annual mining volume of more than 300,000 tons should be further integrated, and large-scale mining and intensive operation should be implemented; detailed information on existing mining areas should be implemented. Investigation, mining according to mining design, key mines to make up for the debts of rock stripping, prolong the service life of mines; promote the beneficiation technology, comprehensive utilization of low-grade ores. At present, relevant companies have gradually realized that only relying on raw ore to produce raw materials can no longer maintain the production of high-quality raw materials; only by beneficiating and purifying raw ore, can they produce high-quality primary raw materials and ensure the normal production of raw materials. Following the successful launch of the flotation system in the Haicheng Magnesium Mine General Plant, many companies have built flotation projects, and other companies have begun preparations. At the same time, the comprehensive utilization of flotation tailings is also under study.

In the next 3 to 5 years, the promotion of magnesite flotation technology, the use of Tibetan cryptocrystalline magnesia and the subsequent processing of high-purity Mg(OH)2 produced by Qinghai "Salt Lake Magnesium Extraction" will be China's magnesia production Provide high-quality raw material supply guarantee.

Production of high-quality light burnt magnesia

According to foreign exchange data, the global annual consumption of light burned magnesia (CCM) is about 10 million tons. China is the world's largest producer of light burned magnesia, with an annual output of 3.5 million to 4 million tons. In Japan, the United States and other countries, the ratio of light burned magnesia used for sintered magnesia to non-refractory materials was 80:20 in the 1990s, and then gradually changed to 70:30, and is now roughly 65:35. Large-scale light burning plants built abroad have a wide variety of products and a wide range of uses. Therefore, not only should focus on the development of light burned magnesia (CCM) use and application to refractory materials, but also should vigorously cultivate new magnesite material industries such as magnesium chemical industry and magnesium building materials to adjust the product structure of light burned magnesia. Only by establishing a large-scale light-burned magnesia centralized production base and forming a scale effect can there be reasonable investment, so as to adopt advanced roasting technology and furnaces to solve the problems of energy saving and emission reduction, development of low-carbon economy, and CO2 recovery from the source.

In order to produce high-purity magnesia with the "two-step calcination" process in the southern area of Central Liaoning, not only the traditional reverberatory furnace light burnt magnesite nugget ore, but also the light burnt magnesite flotation concentrate from foreign suspension furnaces was introduced. Magnesite crushed ore is lightly burned in rotary kiln, boiling furnace, and new type suspension furnace. For example, the commissioning of a multi-storey furnace (MHK) of a certain enterprise and the large-scale jet suspension furnace for roasting Al(OH)3 in the non-ferrous metal industry and the decomposing furnace outside the cement industry kiln provide favorable conditions for the selection of light-burning magnesia kilns.

Develop low-cost and high-grade magnesia

It is generally believed that the global high-end refractory material market requires 98% MgO content of high-grade magnesia, the bulk density of sintered magnesia is 3.40 g/cm3, and the bulk density of fused magnesia is 3.50 g/cm3. The annual consumption of high-grade magnesia in high-temperature industrial sectors such as steel and cement is about 1 million tons.

The total annual output of sintered magnesia in China is about 4 million tons. Around 1980, the export volume of cheap Chinese natural magnesia soared, and it has always occupied the international low-end magnesia market. In general, the current supply of low-end magnesia in the market exceeds demand, and the output of this part of sintered magnesia should be controlled, especially the production of re-burned magnesia should be gradually reduced. Due to the decline in ore grades and the rise in fuel and labor prices, the quality of mid-range magnesia and high-purity magnesia has declined significantly. In the future, the market demand for mid-range and high-purity magnesia will increase, because the trend of mid-range sand to replace heavy burned sand and high-purity sand to replace part of fused sand upward is obvious.

After more than 30 years of disorderly mining, it is an indisputable fact that high-quality magnesite ore has decreased and the quality of magnesia has decreased. At present, relevant enterprises gradually realize the importance of ore flotation and purification, and it is an inevitable trend to promote mineral processing technology. Starting with ore beneficiation to improve the grade of ore, use energy-saving and efficient light-burning equipment to produce high-activity light-burned magnesia, and improve the quality of high-purity sand through production methods such as dry high-pressure dry ball and clean fuel high-temperature calcination. It is also necessary to explore new processes and processes for the production of magnesia, in order to produce high-grade sintered magnesia with a 98% MgO content and a bulk density of 3.40 g/cm3 at a low cost. The construction of a large-scale production plant integrating mineral processing and high-purity magnesia production is in line with the future development direction.

Improve fused magnesia technology and equipment

Due to the extremely competitive price of China's fused magnesia, a large number of western seawater magnesia manufacturers have closed down. At present, in the world market of fused magnesia with MgO content >98.5%, China occupies 90% of it, and its application is more extensive. However, this product has high energy consumption and requires high-quality raw materials. Therefore, the comprehensive promotion of improved technical equipment measures in the fused magnesia industry will help reduce energy consumption and control quality, which is an inevitable trend for future development

At present, Liaoning's magnesia-based synthetic raw materials mainly include fused magnesia chromium sand, sintered magnesia calcium sand, sintered magnesia alumina spinel sand, sintered magnesia alumina iron sand, etc., with an annual output of more than 200,000 tons. Magnesia-calcium refractories have excellent performance, but their application is limited due to the hydration problem of CaO. Therefore, the water-repellent problem of magnesia-calcium refractories should be studied. It should be pointed out that, due to the presence of CaO, magnesium-calcium refractories have the effect of removing sulfur and phosphorus impurities in steelmaking; while CaO exists, it is impossible to not hydrate, only to prevent its hydration.

With the increase in environmental protection, chromium-containing refractories will withdraw from the market, and the research and production of alternative products is imperative. Therefore, MgO-Al2O3, MgO-CaO, MgO-ZrO2, MgO-SiO2 should be further developed and produced for different purposes. , MgO-Fe2O3, MgO-CaO-Fe2O3, MgO-Al2O3-ZrO2, MgO-CaO-ZrO2, MgO-Al2O3-Fe2O3 (FeO) and other high-quality synthetic magnesium raw materials.

Generally speaking, as a non-renewable and indispensable strategic resource, magnesite is the focus of all related work in the future to limit and reduce its mining and improve its resource utilization. Therefore, the country should greatly reduce the export quota of magnesia and restrict the export of low-value-added raw materials and ordinary magnesia products.

At the same time, enterprises with mining resources and conditions are encouraged to carry out large-scale technological transformation and equipment renewal, or to decentralize the mining of raw materials, and to concentrate on the construction of a number of large-scale raw material bases. Rock stripping in mines, purification of low-grade ore, construction of large-scale light-burning and calcining equipment, and industrialization of new sand making processes require a lot of capital and new technical support, and there are certain risks. I hope that relevant national departments will provide policies, funds, and technology. And other aspects of support.