In order to achieve the purpose of desulfurization, dephosphorization and slag removal, the raw materials of limestone require: low S content (less than 0.015%); High activity degree (> 350mL); The particle size control is 0.01~ 1mm; The surface passivation ensures good ductility and fluidity to overcome the disadvantages of easy moisture absorption, hard storage and transportation. In addition, the commonly used by refining outside the furnace injection spray lime powder metallurgy method, also requires fine lime powder particle size and uniform, and active degree is high, waterproof, low content of S and surface passivation, facilitate storage transport.
For hot metal pretreatment and refining outside the furnace process requirement for lime powder in use in the process design processing lime powder pulverizing equipment, here are several pulverizing equipment of pulverizing effect are introduced and compared.
limestone Raymond mill
The limestone Raymond mill is also called suspension roller mill or pendulum mill. It is commonly used for grinding fine equipment, which is mainly used in metallurgy, building materials, chemical industry, mining and other mineral materials. Powder grinding range is a variety of non-flammable and explosive materials with a hardness of less than 7. The size range of grinding finished product (0.125 ~ 0.04mm, i.e., 100 eyes ~325 eyes, which can reach 500 items) is adjusted according to different requirements. The limestone Raymond mill is mainly composed of main engine, analyzer, fan, product cyclone separator, micro-powder cyclone separator and duct.
Raymond mill works: limestone grinding machine allows feed particle size of the block material, the uniform feeding device continuously into the host, grinding, grinding powder by blower after circulation wind flow, with the analysis on the host at the top of the machine for grading. The fine - sized powder will enter the large cyclone collector with the air flow, and the finished product will be discharged after collecting. The air flow from the upper end of the large cyclone collector flows into the blower, and the entire wind system is closed loop, and most of it flows under negative pressure.
Because of the moisture in the mill materials, the vaporization of vaporization into the gas during grinding and the gas leaking into the air ducts under negative pressure in the whole air duct, resulting in the increase of wind volume in the circulation wind road. This increase of air volume, from the blower and the main engine intermediate wind tube into the small cyclone collector. With the current and the wind, a few fine powders are brought into the atmosphere. After being collected by a small cyclone, it is discharged by another pulverized tube, which is discharged into the atmosphere by the exhaust pipe at the top of the small cyclone collector.
The structure features of limestone Raymond mill: the three-dimensional structure is small and the whole set is strong. From the block, it is expected that the finished product can be independently produced into a production system. The fine uniformity of finished product and 99% of the screening rate are difficult to be found in other mill equipment. The transmission device adopts sealed gearbox and belt wheel, which is stable and reliable. All the important parts are made of high quality steel, the wear-resistant parts are high performance wear-resisting material, the whole machine has high wear resistance and reliable operation. The electric system adopts the centralized control, the grinding workshop can realize the unattended operation, and the maintenance is convenient. It is worth noting that feed capacity is more sensitive in limestone Raymond mill, if the feed is insufficient, the equipment running under load, will have a bigger noise, and the equipment main body and the vibration of the equipment foundation to produce significantly.
The investigation found that some of the manufacturers who used limestone Redmond to grind lime powder had removed one of the suspension rolls and some had removed the cyclone. The main reason is: the water content of the raw material lime itself is low, the steam produced in the grinding process is small, and the influence on the air pressure inside the mill is small. The required finished lime only requires that the particle size reach a certain range (usually < 1mm up to 100%), without grading, and fine powder can be used as the finished product; The local environmental protection requirements are not high.