Currently, the total output of sintered magnesia in our country was 4 million to 4.5 million tons per year. Following the industry habit, light burning magnesium ball can be roughly divided into heavy burning magnesia, medium grade magnesia, high purity magnesia. Before the 1980s, for more than 30 years, the production of sintered magnesia in China was mainly undertaken by the former Anshan Iron and Steel Dashiqiao magnesia Mine, which successively adopted shaft kilns of 25 cubic meters, 32 cubic meters, 40 cubic meters, 47 cubic meters and 55 cubic meters, using coke as fuel and massive magnesite as raw materials. The refired magnesia with 92% MgO content is produced by one-step calcination and manual discharge, which provides raw materials for steelmaking open hearth bricks in China. Magnesia manufacturer
The defects of this process are: the ore utilization rate is low, the fine particle ore can not be used; High impurity content, ash in coke will cause pollution to magnesia, so that the content of SiO2, Al2O3 increase, Z high MgO content can only ensure at 92%; The continuous operation is poor. Large magnesite ore is decomposed by heat and produces small particles attached to the kiln wall. The materials in the kiln are prone to "clump". The density of magnesia is low. The magnesite decomposes in the kiln and releases CO2 to become lightly fired MgO, but its MgCO3 "master salt false" still exists, which is not conducive to the further densification of magnesia. The bulk density of sintered magnesia is only between 3.0 g and 3.1 g per cubic centimeter. Serious environmental pollution, magnesite decomposition of a large number of CO2 and burning flue gas mixed with fine coke particles and light burning dust fly out of the kiln, pollution of the environment, high temperature flue gas treatment is difficult. At present, Chinese heavy magnesia is still calcined in solid fuel shaft kiln with secondary and tertiary ores, the content of magnesia MgO is 90%~92%, and the bulk density per cubic centimeter is more than 3.10 grams. Refired magnesia is the main raw material for the production of ordinary magnesia fired bricks and amorphous refractory materials. The current annual output of Liaoning Province is estimated at 2.5 million tons. Due to the use of tertiary mines, low product price and market, it is difficult to eliminate at present. Medium grade magnesia. In order to increase the density and purity of magnesia, the process research and industrial tests of two-step burning magnesia are carried out in our refractory industry. The application of new technology and process suitable for national conditions has promoted the technological progress of sintered magnesia production. In the early 1980s, Haicheng magnesia produced medium grade magnesia with MgO content ≥95% and volume density ≥ 3.20 grams per cubic centimeter by light firing of high quality magnesite in reflector furnace, fine grinding with Ramen grinding, semi-dry two-stage press ball and shaft kiln calcining of coke. The results spread rapidly, forming economies of scale with an annual output of hundreds of thousands of tons. Since then, the process has been widely used to produce synthetic sand products such as synthetic magnesium-calcium sand.