Anshan Magnetic iron ore is an important iron ore resources, for magnetite, magnetic separation is the most effective and most economical method Anshan magnetite beneficiation belong metamorphosed sedimentary deposits, is a disseminated iron ore, The natural type of ore is mainly iron-bearing quartzite , composed of quartz (or amphibole) and magnetite (sometimes imaginary hematite). Iron ore is divided into two types: lean ore and rich ore, and is mainly characterized by strip-like structure. In the practice of magnetic separation production in China, most of the ore processing plants dealing with magnetite ore use stage grinding and stages. The selection process. In order to meet the growing demand for iron ore quality in the iron and steel industry, and to produce high-quality concentrates and ultra-pure concentrates, a large number of experimental research work has been carried out at home and abroad. For example, some concentrators have increased the number of sorting; some concentrators have magnetic separation The concentrate is repeatedly selected to separate the continuum and the monomeric quartz mixed in the magnetic separation concentrate; some of the concentrating plants add excitation and fine sieving and grinding to form a loop, and the sieved product is sent to the Grinding Machine for re-grinding. The undersize product is magnetically selected to reduce the amount of silicon in the concentrate, so that high quality iron concentrate can be obtained. For the separation process of magnetite hematite mixed iron ore, great progress has been made in recent years, especially the application of strong magnetic field magnetic separator to treat hematite ore, which can directly select a large number of qualified final concentrates. Some use the magnetic weight combined process to select, but also achieved a good beneficiation index. The ore processed by a factory is a typical Anshan-type lean magnetite ore. The iron minerals in the ore are mainly magnetite, with a small amount of imaginary hematite and limonite. The gangue mineral is mainly quartz. Followed by pyroxene, hornblende, mica , feldspar, etc. The ore is in the form of a strip-like structural strip consisting of an iron mineral layer and a gangue mineral layer. The embedding grain size of the magnetite in the ore is generally 0.2 - 0.3 mm, and the continuous mineral state of the useful mineral in the ore is compared. simple. The particle size of quartz in the gangue mineral is generally 0.2-0.5 mm and the particle size of the pyroxene is relatively fine. The looseness coefficient of ore and rock is about 1.5. The ore has a Platt hardness of 8 to 12 and belongs to medium hard ore. The density of magnetite is 3200kg/m3, the rock density is 2700kg/m3, and the ore grade is generally 26%~27%. To handle this type of ore, the plant uses a stage grinding process and a phase selection process, as shown in Figure 7-1. In this process, the ore is first coarsely ground to -200 mesh, accounting for 30% -40%, so that the gangue mineral layer and the iron mineral layer are substantially dissociated, and the coarsely ground product is partially separated by a rough selection. Need to re-grind and re-select the coarse concentrate. After the coarse concentrate has been honed, -200 mesh accounts for 65% -70%. At this point, most of the iron minerals and gangue minerals are separated by monomer. After the fine grinding, the coarse concentrate is again subjected to secondary magnetic separation to remove some qualified tailings: the secondary magnetic separation concentrate is fed into the fine sieve, and the sieved product enters the cone hydraulic classifier to be upgraded again, and the fine-grained product and fine The undersize products of the sieve are combined, subjected to a second magnetic separation, a portion of the tailings is discarded, and the final concentrate is obtained. The coarse satin product of the hydraulic classifier enters a ball mill for regrind. The secondary ball mill and the hydrocyclone and the conical hydraulic classifier form a closed loop. The beneficiation index obtained by this process for treating such magnetite is: the original ore grade is 26.87%. Concentrate grade of 68.59%, 76.45% metal recoveries The ore processed by a factory is also Anshan-type magnetite. The main metal minerals in the ore are magnetite, imaginary hematite and hematite, followed by limonite and a small amount of carbonate minerals. The main gangue mineral is quartz, followed by the actinite chlorite, mica, dolomite and other ore structures. The main magnetites are strip-shaped and massive. The magnetite is mostly self-crystallized and semi-automorphic, and some of them are coarse-grained. . There are still a small number of fine-grained veins, which are wrapped by stone. The crystal grain size of minerals is very uneven. The magnetite particle size is 0.174-0.043mm, the coarse one is 0.711mm, the fine one is 0.005mm or less, less than 15um. The following accounted for 4 76%, and some were present in inclusions. The average particle size of iron minerals is 0.05 mm. The quartz particles in the ore are all below 1 mm, mostly 0.025~0.125mm and 0.125~0.062mm, with an average ore hardness of 0.078mm, f=10~18 and density of 3.3. After the plant's magnetic separation workshop was put into production, a single magnetic separation process was set up between the two stages of closed-circuit grinding. After two sections of ore grinding, the ore size is -200 mesh, accounting for 80% to 63% of the concentrate grade. In order to improve the final concentrate grade, the plant reforms the original process and adds fine after the stage grinding. The sieving re-grinding operation, the stage grinding, fine sizing and re-grinding process start production, and the process flow is shown in Figure 7-2. It can be seen from the flow chart that after the ore is sorted by the stage grinding stage, the final concentrate and tailings are obtained after two stages of fine screening, one section of grinding and three sections of magnetic separation. After magnetic separation plant to increase fine sieve and then grinding operations, concentrate grade increased by about 3%, which is a major advance in the mineral processing technology. However, after adding fine screening and re-grinding operations, the process flow is more complicated, and the number of working sections is large, which brings many difficulties to operation, management and maintenance. As a result of the increased grinding and conveying equipment, the consumption of electrical energy and various materials is increased, and the cost of beneficiation is increased. In particular, the process does not make full use of the uneven grain size of the ore. The separation between the first and second stages of grinding only discards the final tailings and does not obtain the final concentrate, so that the iron minerals that have reached the monomer dissociation are obtained. The over-grinding has affected the improvement of metal recovery rate, increased the load of the secondary grinding machine, and wasted equipment capacity. In order to solve the above problems and reduce the production cost, the engineering and technical personnel of the plant proposed to reform the existing process, and adopt the phase grinding and magnetic weight combined process instead of the single magnetic separation and fine screening regrind process, such as Figure 7.3 shows. The stage grinding and magnetic weight co-option process fully utilizes the non-uniformity of the ore crystal grain size. After the stage grinding, the magnetic concentrate can be used to sort out the final concentrate and tailings. Reduced secondary grinding, thus reducing unnecessary over-grinding and metal loss, which is beneficial to improve metal recovery. Compared with the stage grinding, fine screening and regrind process, the new process is more reasonable, the number of equipment is reduced, the regrinder and part of the conveying equipment can be omitted, and the production operation, technical management and maintenance are all advantageous. In addition, it can be seen in the new process flow that the stage grinding and the magnetic weight combined selection method are used to carry out the fine and fine particle sorting after the fine screening and splicing, and the spiral chute and the triple barrel magnetic separator respectively recover the coarse and fine concentrate. Generally, the magnetic separator removes most of the coarse tailings in advance, and the medium ore is subjected to secondary grinding. Returning to the original loop is a few prominent features of the process. After more than two years of industrial test results, this process can be selected to save energy and increase revenue and improve economic efficiency. At present, the magnetic separation workshop of the plant has adopted the new process of phase grinding magnetic re-election to replace the current single magnetic separation and fine screening regrind process. WEISS MACHINERY CO., LTD. , https://www.weissmachinerys.com