Preparation of a-Al2O3 fine powder and ultrafine powder and ultrafine powder are also called fine powder and ultrafine powder. With its particle size as the criterion, a-Al2O3 fine powder with a aluminum oxide abrasive particle size of not more than 90um is generally referred to as micropowder or ultrafine powder. The particle size limits of both fine powder and ultrafine powder are not unified in various industries. The refractory industry at home and abroad generally uses 5um as the limit between the two.
For ball mill pulverization, as the ball milling time increases, the fineness of the raw material becomes finer, and the speed of thinning is faster at the initial stage and slower at the later stage. This is because the pulverized fine powder forms aggregates under the action of molecular cohesion and prevents further pulverization; at the same time, the fine powder acts as a buffer for large particles Effect, making larger unpulverized particles difficult to further pulverize. For fine powder.
Al2O3 is the main component in bauxite. The higher the content, the better. Therefore, the smelting of brown corundum requires the use of high-quality bauxite as much as possible. After the emery abrasive material is crushed to a certain fineness, a grinding aid is added. It is characterized by adding excessive carbon reduction in the middle stage and decarburizing agent in the later stage. However, when the ball milling time is extended to a certain limit, the pulverization effect is reduced.
At present, the production of industrial alumina requires an aluminum-silicon ratio of not less than 3.0 to 3.5. Other oxides are regarded as impurities. SiO2 is a harmful impurity in the production of alumina by the alkaline method. The high content of SiO2 in bauxite will reduce the production efficiency of smelting brown corundum or the production of industrial alumina and increase the impurity component. Al2O3-H2O crystalline compounds can be prepared by artificial methods.
The quality requirements of high alumina bauxite include chemical composition, dehydration degree, particle size, etc., because these factors will affect the brown corundum smelting technical indicators and product quality to varying degrees. High alumina bauxite is the raw material to provide Al2O3, which is the main component of green carborundum. The higher the Al2O3 content, the better the various technical indexes of smelting corundum. With the increase of Al2O3 content, the unit power consumption decreases.
As we all know, special refractories are a group of new refractories developed on the basis of traditional ceramics and refractories, also known as high temperature ceramics. Ceramic is named after technology. Usually, products made by powder making, molding, sintering and other processes are called ceramics. It can also be said that special refractories are refractory products made of ceramic production process. The slurry shall have good suspension and fluidity.
For this reason, some factories are committed to the production of sintered corundum directly by one-step grinding of industrial alumina. After the material is adsorbed on the particle surface, it can not only de coagulate, but also improve the aluminum oxide sandblasting media grinding efficiency due to the reduction of the particle surface energy. The addition of grinding aid can reduce the water consumption, improve the dispersibility and the fluidity of mud, which is conducive to the smooth progress of ultrafine grinding.
Generally, adjust according to the actual stick color. That is to say, the former and the middle stage are reduction smelting period, and the later stage is oxidation refining period. After the reduction smelting period, it enters into the oxidation refining period. During the oxidation refining period, the unmelted layer on the upper surface of the furnace pool shall not be too thick, and the material shall not be added any more. At this time, decarburization begins.