Raymond Mill's history 1906 and C.V.Grueber founded CurtVonGrueber Machinery Factory in the southern suburbs of Berlin, and used his patent in the United States to produce the first Maxecon mill, which was used as coal grinding equipment in MOABIT Power Station in Bevage, Berlin. The grinding energy reached 5T/H, and nearly 600 sets were sold in a few years, which were used in the grinding field of different industries. BEWAG plans to build a coal mill with higher output at the same time. After E.C.Loesche became a shareholder and took charge of CurtVonGrueber Machinery Factory, he decided to purchase the raymond centrifugal ring roller mill patent published by the United States and produce the first generation raymond mill system. Its structure is that a rotating spindle with a plum blossom frame is erected in the center of the machine, and three or more self-rotating grinding rollers are hung on the plum blossom frame. The rotating shaft rotates at a certain speed, which drives the grinding roller to swing outward, and is driven by centrifugal force to press against the grinding ring embedded in the inner wall of the cylinder. When the material enters the grinding area, the material is brought to the front area of the grinding roller under the action of plow-shaped guide blades below the grinding roller. Because the grinding force (centrifugal force) of Raymond coal mill roller is limited by the diameter and speed of the roller, the mill at that time was only suitable for soft, low-ash and easy-to-grind coal materials. However, the coal quality in Germany is hard and has high ash content, which requires higher grinding power. Raymond mill with this structure is difficult to meet the requirements of grinding, so Raymond mill has not been popularized in Germany. At that time, Raymond coal mill was just suitable for the grinding requirements of coal quality in the United States, so Raymond coal mill was widely popularized and applied in the United States.
1925, E.C.Loesche summarized the use characteristics and structural deficiencies of the first generation of Raymond mill, and decided to further improve the grinding structure of Raymond mill, and developed a mill with the opposite grinding principle, which was called improved Raymond mill. The main structural feature is that the bowl-shaped grinding ring rotates, the grinding roller is pressurized by the mechanical spring load to increase the grinding force, and the material is fed into the bowl-shaped grinding ring from the center and brought into the grinding roller by the rotating centrifugal force. The grinding roller shaft is fixed on the unidirectional movable rocker arm, and the grinding force of each rocker arm is controlled by an adjustable spring. The ventilation of this improved Raymond mill system has two ways: positive pressure and negative pressure direct blowing. This type of Raymond Mill patent was quickly purchased by American Combustion Engineering Company. Because the improved raymond mill still has the problem of ring roller grinding, although the roller diameter increases slightly, the grinding force does not increase much. Later, Raymond Branch of American combustion engineering company developed a new generation of Raymond mill called VR mill. This Ramon mill has many similarities with the Lech mill in structure. It is worth noting that it is different from Lechermill's conical grinding roller and plane grinding disc, but adopts cylindrical grinding roller and grinding disc, and the inclined grinding surface angle of the grinding disc is 65438 05 degrees. During inspection and maintenance, the grinding roller is equipped with a turnover device similar to Lechermill, and also equipped with a protection device to prevent metal contact between the grinding roller and the grinding disc. In addition, the grinding roller can be lifted in advance before the mill starts, which can reduce the starting torque of the motor. In the industrial application of Raymond mill in the United States, it is usually used to prepare pulverized coal. The fineness of the product varies between 250-325 mesh, and the fineness and output of the product can be adjusted during operation. Hardness and Mohs hardness
Hardness: Because it is a destructive test, it can only be used for unrefined raw stone or non-precious ore. There are two scales of hardness, one is absolute hardness and the other is Mohs hardness (a relative hardness).
Mohs hardness: based on ten common minerals, scratch each other to distinguish which is hard and which is soft. Traditionally, Mohs hardness is used in mineralogy or gemology.
Mohs hardness is divided into ten grades. Talc, gypsum, calcite, fluorite, apatite, orthoclase, timely, topaz, corundum and diamond.
The purpose is to generally characterize the pore size of molecular sieve, and its conversion formula is:
Cm = 16/ mesh
There are English and American systems. English means the number of holes per square inch.
Comparison between new ultra-fine Raymond mill and traditional Raymond mill: Raymond mill, also known as Raymond mill, mill, Raymond mill and high-pressure suspension roller mill, is a widely used grinding equipment. Raymond mill is a kind of grinding equipment widely used in mines, cement plants and chemical plants, and it is one of the important equipment for deep processing of nonmetallic minerals. Raymond mill has been introduced to China for more than 20 years. Because of its stable performance, strong adaptability and high cost performance, it has been widely used in non-metallic mineral processing. However, with the extensive development of nonmetallic minerals in the application field of ultrafine powder, downstream enterprises have higher and higher requirements for nonmetallic minerals. In particular, the requirements for product fineness are higher. This makes the traditional Raymond Mill seem powerless. These traditional problems in raymond mill have been puzzling mineral processing enterprises and equipment manufacturers. These problems are mainly manifested in: