As an important national strategic resource, mineral resources play an important role as an important basic raw material for social and economic development. Iron ore faces huge opportunities and challenges, and should have a lot to do. However, the quality of domestic iron ore is getting lower and lower, while the quality of iron ore concentrate in blast furnace ironmaking is becoming more and more strict, and the import of high-quality iron ore from abroad is continuously imported. Strongly impact the domestic iron ore market. At present, the iron ore processed by domestic concentrators mainly consists of magnetite and hematite. Among them, the output of magnet concentrate accounts for about 3/4 of the output of iron concentrate in China, and most of the iron ore mines in China are in the process of mineral processing technology innovation. The main targets are also the two types of ore. China's iron ore resources are relatively abundant, and in terms of reserves, it is second only to Russia, Canada, Australia and Brazil [3]. Among the iron ore resources, Anshan-type iron ore is the most widely distributed and is the most important iron deposit in China. Its reserves account for more than half of the total iron ore reserves in the country, and the scale is generally large. Its ore type is magnetite. Mainly, it is the most important type of ore selected by the current domestic iron ore dressing plant. The more successful new processes that have emerged in recent years are mainly: “stage grinding, weak magnetic separation – reverse flotation processâ€, “full magnetic separation sorting processâ€, “ultrafine crushing-wet magnetic separation tailing process†". 1. Full magnetic separation process The full magnetic separation process is based on the existing stage of grinding, weak magnetic separation, fine screening and re-grinding process, and then selected by high-efficiency fine screening and high-efficiency magnetic separation equipment . Compared with the reverse flotation process, the process is simple, the process is reliable, the investment is saved, the construction period is short, and the operation is easy. The ore selected from the Shougang Mine Concentrator is an Anshan-type lean magnetite. The ore is in the form of strips and hemps. The metal minerals are mainly magnetite, with a small amount of hematite. The whole magnetic separation process is selected in the Shougang Mine. For many years, its iron concentrate grade has been maintained at around 67%, and has won the national championship of iron concentrate quality [6]. The domestic full magnetic separation process with high-frequency vibrating screen, BX magnetic separator, magnetic separation column and disc filter as the main equipment is first adopted in Benfen Nanfen Concentrator and Shantoushan Concentrator. The process is accurate. The opening is small, which is reasonable and economical for optimizing the overall process flow and achieving the ultimate goal of reducing silicon and iron. The application results show that the iron grade of concentrate can be increased to about 69.5%, the SiO2 content in the concentrate is reduced to below 4%, the tailing grade and metal recovery rate are basically unchanged, and the newly added processing cost is less than 20 yuan/t. 2. Ultra-fine crushing-wet magnetic separation tailing process The process is to finely crush the ore to 5 mm or less, and then perform wet magnetic separation and tailing with a permanent magnet medium field magnetic separator. This process is particularly important for energy saving, efficient use of extremely poor iron ore and improved final iron concentrate quality. In order to develop and utilize iron ore with a grade of less than 20%, the Magang Gaocun Iron Mine has used a high-pressure roller mill to crush the ore to less than 3 mm, and the midfield strong wet magnetic separation to remove about 40% of the coarse tailings. The iron grade is increased to about 40%. After re-grinding and re-election, the final iron concentrate is obtained. The final iron concentrate grade is over 65%, the SiO2 content is below 4%, and the tailings grade is below 10%. In addition, Shandong Laiwu Iron Mine, Jinling Iron Mine, etc. use the hammer crusher-wet permanent magnet midfield strong magnetic separation process, the size of the selected material is -5mm, accounting for more than 80%, and the yield can be thrown by 30%~40%. Coarse tailings. 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Analysis of Mine Mineral Processing Technology in China at Present Stage
Our total iron ore reserves of about 46.232 billion t, of which more than C-class reserves of about 22.031 billion t [1,2], accounting for 17.86 percent of total world reserves. The characteristics of China's iron ore are: (1) more rich ore, less rich ore. The average grade of ore is low, the lean ore accounts for 97.5% of the total reserves, and the rich ore only accounts for 2.5%. (2) complex type of ore, oxide ore, and multi-metallic hard dressing stone coexistence ore more, and embedded in fine particle size distribution. Therefore, almost all of the mined ore needs to be processed by beneficiation to improve the comprehensive utilization level of smelting raw materials and useful ingredients.