With the increase in the amount of lean ore mining and the need to strengthen mining and increase the recovery rate of mining, the problem of depletion of ore caused by the surrounding rock and stone mixed in the ore is becoming more and more prominent. To reduce the processing plant capital investment, to reduce production costs, energy saving, it is carried out before the preselection ore ores into the mill, and has more than 30 selected from iron ore field applications, good results in. Nearly 30 pre-selected methods have been used in the magnetite ore plant, mainly for dry sorting of magnetic pulleys. There are two types of magnetic pulleys, electromagnetic and permanent magnet. They are mostly permanent magnets. The specifications are 1200*1275, 1050*1400, 1100*1100, 800*800, 800*1200, 1000*970, 600*800mm and other different forms. A variety of specifications. Mineral ore from the rock has selected a variety of particle sizes between 350 ~ 0mm to 15 ~ 0mm, tailing rate is generally about 10%. The surrounding rock throwing rate can reach about 80%. The pre-selection method for weak magnetic iron ore is mainly re-election and strong magnetic separation. The re-election method was applied earlier, and the strong magnetic separation method was applied in the 1980s. Strong magnetic separator is mainly CS series magnetic separator, selected size 14mm or less in recent years developed a neodymium-iron-boron permanent magnet material magnetic separator bar chain that can handle the ore 15-4mm. The re-election is mainly to apply the vibration chute. The maximum strength of the ore can be up to 75mm, and the throwing rate can reach 20%~50%, as well as the trapezoidal jig. The large-grip jig that has appeared in the past 80 years can handle ore of 75mm, 50mm and 30mm, and the throwing rate is 20% to 50%. The development of the circular jig has also obtained industrial test results. Single Tub Washing Machine,Single Tub Semi Automatic Washing Machine,Shoe Washing Machine Ningbo Wutongshu Electric Appliance Co., LTD , https://www.washingmachinewts.com