| The iron ore resource in China is very rich, only behind Brazil, Australia, Ukraine, Russia, and ranking fifth in the world. By the end of 2013, there are about 82 billion tons ore resources reserves in China, and the retained reserves of iron ore resources are about 780 billion tons. Compared with foreign iron ore, the iron ore resources in China is much more difficult to be separated because of its characteristics of larger lean ore, rich associated elements, complex components, small mine dimensions, although the iron ore resources in China is rich.As a representative large iron mine in China, the resources of iron in Dahongshan Iron Mine is rich, geological resources reserves of mineral right range up to 568 million tons, and the amount of iron ore, copper ore and copper metal is 485 million tons,82 million tons and 539400 tons, respectively. Due to the exists of isomorphous iron in the gangue minerals, which leads to the high specific magnetization coefficient and density of silicate gangue, the specific magnetization coefficient of silicate gangue is very similar to hematite limonite; in addition, magnetite and hematite limonite have fine embedded granularity, the account of-19μm of magnetite and hematite limonite are more than 15% and 33%, respectively; part of hematite limonite structure is like oolitic, the difference of hardness between magnetite and hematite limonite is large, the particle of magnetite is coarse and hard to be ground, while the particle of hematite limonite is fine and easy to be ground, which leads that partial iron mineral are easier to be over-crushed or have less dissociation degree, and mud phenomenon will be happened and lower flotation efficiency. Therefore, during actual production process, the grade of tailings in Dahongshan Iron Mine is more than 16%, and shows the characteristics of "Two low-Four high-Three nearly", namely the grade of sub-concentrates and the proportion of magnetic iron are low. The content of silicates, silicon of strong magnetic concentrates and sub-concentrate, the micro fine of the products of crushing, grinding and tailings and iron in tailings are high. And the density, surface chemical properties and specific magnetization coefficient of main gangue minerals is nearly to iron mineral.During the research, which use the refractory iron ore of Dahongshan iron concentrator as the main object of study, a series of "Increase output", "Drop tailings" and "Quality improving and Silicon reduction" research and an industrial applicaton tests are carried out. On the basis of small laboratory experiment, a series of industrial application tests on technical process and key technology to recovery iron effectively are carried out, which made the obvious features of research and innovation achievements.(1) The SAB crushing process was improved to the SABC crushing process, and blind flanges transformation of NO.2 beneficiation plants’ semi-autogenous mill, raised the handling capacity of semi-autogenous mill successfully. After blind flanges transformation, the handling capacity of NO.2 beneficiation plants can add 383.5 kilotons every year, and the output of iron concentrates can add 181.8 kilotons every year.(2) On NO.2 beneficiation plants, through the drop tailings flow of combined high magnetic-centrifugal separator-shaking table separate tailings of second-stage high magnetic separation, the iron grade of NO.2 beneficiation plants tailings could be reduced from 16% to 13%. Through the combined magnetic-gravity flow of one roughing-one cleaning-one scavenging separate tailings of first-stage high magnetic separation, the iron grade of NO.2 beneficiation plants tailings could be further reduced to 11.5%. Through the depth drop tailings flow of high magnetic- shaking table- high magnetic separate final tailings of NO.2 beneficiation plants, finally, the iron grade of NO.2 beneficiation plants tailings could be reduced to 8.11%.(3) The first time large-scale application of a new-type centrifugal separator equipment in China, which solved the technical problem of improving the quality of high silica-bearing fine high magnetic iron concentrates, and leaded the trend of large-scale continuous centrifugal concentrating machine applied in ultra-fine hematite mineral recovery in the domestic. The content of -45μm is 58.6% in magnetic concentrates with high content of silica, the mosaic size of iron and quartz is fine and the symbiosis relationship of them is complicated; when using green and economic technology to improve the quality of iron and reduce silica, the grade of concentrates and the content of silica raised from 50% to 61% and droped from 15% to 5.8%, and the rate of increasing and reduction were 22.0% and 61.33%, respectively.(4) A reverse flotation for desilication was carried out, which use the sub-concentrates with high content of silica as the main object. Under the conditions (a grinding fineness-45 μm is 70%, using a new collector YB), an iron concentrates with a recovery of 89%, through a reverse flotation with one roughing, two concentrates and two scavengings, was obtained. The grade of iron concentrates increased from 35% to more than 52%, the rate of increasing was 48.57%.(5) Through the application of key integration technology in three concentrators, respectively. The technical index and processing capacity has been greatly improved; the iron average grade of tailings reduced to 10.8%, iron metel losses 192200 tons annually. The iron grade of 50%, SiO2 content of 9% pellet-grade concentrate was improved to iron grade of 62%, SiO2 content of 7% high quality pellet-grade concentrate. The grade of sub-concentrates, pellet concentrates and silica increased from 35% to 52%, respectively. There were saved 3708 tons of coke annually, and emission loads of sulfur dioxide and carbon dioxide were decreased 520 tons and 34 kilotons, respectively. Over the last three years, there were added 1.516 billion yuan of profits and 197 million yuan of taxes, and indirectly saved about 811 million yuan of the smelting cost at the same time.
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