What are the calcining processes of siderite?

The main component of siderite is ferrous carbonate, which is generally in the form of granular crystals or dense blocks, spheres, and gels without crystals. The color is generally gray-white or yellow-white, and can turn into brown or brown-black after weathering. Mohs hardness 4, which decreases with increasing manganese and magnesium content in the composition. Siderite of hydrothermal origin is commonly found in metal veins; siderite of sedimentary origin is common in shale layers, clay layers and coal seams. In the oxidation zone, it is easily hydrolyzed into limonite and forms an iron cap. When siderite accumulates in large quantities and the content of harmful impurities such as sulfur and phosphorus is less than 0.04%, it can be mined as iron ore. Siderite mines in my country are mainly distributed in Hubei, Sichuan, Yunnan, Guizhou, Xinjiang, Shaanxi, Shanxi, Guangxi, Shandong, Jilin and other provinces (regions), especially in western provinces such as Guizhou, Shaanxi, Shanxi, Gansu and Qinghai. Mineral resources account for more than half of the province’s total iron ore resource reserves. Since the theoretical iron grade of siderite is low and often coexists with calcium, magnesium, and manganese, it is difficult to achieve an iron concentrate grade of more than 45% using ordinary mineral processing methods. Generally, gravity separation (jigging, heavy media), coarse-grained strong magnetic separation, roasting magnetic separation and their combined processes are mostly adopted for the beneficiation of single siderite ore with coarse grains or coarse grains embedded in them. For iron ore, roasting and magnetic separation are most effective.

The Daxigou siderite mine in Zhashui County, Shaanxi Province is the largest siderite base in my country. The ore composition is simple. The iron minerals are mainly siderite, followed by limonite and a small amount of magnetite. The iron minerals are also due to Isomorphism contains a certain amount of Mg2♦ and MiP. Based on the characteristics of a high percentage of MgC03 molecules, it can be called magnesite. Gangue minerals are mainly quartz and sericite, followed by chlorite, ankerite, muscovite and barite.
Wuhan University of Technology conducted a neutral atmosphere roasting experiment on Shaanxi Daxigou siderite ore, and examined the effects of roasting temperature, roasting time, cooling method, etc. on the roasting magnetic separation effect. The results show that by applying neutral magnetization roasting-dry natural cooling-off-site magnetic separation technology, the roasted ore roasted under TOOT for 70 minutes is first closed and cooled to 400-SOOT, and then discharged into the air to cool to room temperature, strong magnetic properties can be formed. The magnetic separation process test of magnetite and 7-Fe203 roasted ore obtained good indicators of concentrate iron grade of 59.56% ~ 59.37% and iron recovery rate of 72.03% -73.72%. Xi’an University of Architecture and Technology aims at the problems of small gas-solid contact area, high energy consumption, uneven ore quality, and prone to “over-burning” and “under-burning” in the traditional accumulation siderite roasting process of Daxigou siderite mine in Shaanxi Province. Experiments on suspended magnetized roasting of fine-grained siderite were carried out. Suspension roasting is roasting in a state where gas and solid particles are in violent motion with each other. Compared with roasting processes such as shaft furnaces and rotary kilns, suspended roasting has the advantages of large gas-solid contact area, rapid heat and mass transfer, fast reaction rate, and high roasting ore quality. It has the advantages of uniformity, low roasting energy consumption, and easy implementation of large-scale production. The results show that roasting fine-grained siderite in a suspended state has a large gas-solid contact area and a fast reaction speed. It can reach good indicators in 3 minutes of roasting. During the natural cooling process of roasted ore, different discharge temperatures have different effects on the properties of roasted ore. . 500~ 400<^ is the area of intense phase change. Airtight cooling of the roasted ore to below 400T and contact with air will have little impact on product quality; rapid cooling of the roasted ore in the air can obtain better quality products, such as iron ore concentrate. The grade reaches 60. 07%, and the iron recovery rate is 90. 77%. Changsha Mining and Metallurgy Research Institute conducted industrial tests at the Daxigou Iron Mine in Shaanxi based on the properties of Daxigou siderite. The roasting-magnetic separation-reverse flotation process developed by the research and development achieved a roasted ore grade of 30.08% and a final concentrate grade of 30.08%. The indicators are 61.48%, total tailings grade 8.25%, and metal recovery rate 83.83%.
The Wangjiatan Iron Mine of Kunming Iron and Steel Co., Ltd. is mainly composed of siderite, with occasional limonite scattered. The metal sulfide is mainly pyrite, followed by chalcopyrite and sphalerite; the gangue mineral content is relatively high. It is quartz, followed by sericite and chlorite. Other trace minerals include dolomite, calcite, zircon, apatite and monazite. Siderite in the ore is divided into two types: fine particles (particle diameter less than 0.2mm) and medium-coarse particles. The former are mostly euhedral or semi-euhedral granules, some of which are in the shape of bamboo leaves. The crystal grain size is relatively uniform, mostly between 0.02-0.15mm. The crystal grains are closely embedded with each other to form aggregates or are disseminated with quartz and sericite. Mixed with gangue minerals such as chlorite.
Changsha Mining and Metallurgy Research Institute conducted roasting and flash roasting experiments on Wangjiatan siderite ore, and examined the effects of roasting atmosphere, roasting temperature, roasting time, roasting feed layer thickness, etc. on the roasting effect of siderite, and the effects of roasting The ore has been subjected to mineral processing tests such as grinding fineness, weak magnetic concentrate reverse flotation, and weak magnetic separation to reduce sulfur in Chu ore; a flash roasting test has been conducted on fine-grained minerals. The results show that the highest grade of iron Chu ore obtained from roasted ore beneficiation is 59.80%; using conventional roasting technology to treat Wangjiatan siderite will result in a higher sulfur content in the iron concentrate; flash cutting can reduce the sulfur content during the roasting process. For the purpose of sulfur, the sulfur content of iron concentrate is less than 0.20%, and at the same time, a recovery rate of 4.72% higher than that of conventional roasting can be obtained. Liu Ningbin and others introduced the laboratory and field tests of Wangjiatan siderite sintering by soil method, sintering machine sintering, as well as the test situation of siderite roasting and magnetic separation laboratory. Studies have shown that using the indigenous sintering process to sinter Wangjiatan siderite is one of the methods to effectively develop and utilize Wangjiatan siderite resources; adding a certain amount of hematite powder can improve the pelletizing and granulating performance of Ran siderite and The earth burning effect has a positive effect; by selecting the appropriate material structure and determining the appropriate process and operating parameters, earth sinter can be produced that meets the needs of blast furnaces below 100m3; the use of machine burning is the best way to develop and utilize the Wangjiatan siderite resources. One of the fastest ways to choose and get results. Using 10.00% Wangjiatan siderite in equal amounts to replace low-iron powder acidic sinter production in the secondary combustion will have varying degrees of impact on the sintered output, quality and technical and economic indicators. The results of the use of blast furnaces show that the second burnt ore produced by adding Wangjiatan siderite can meet the production needs of small and medium-sized blast furnaces if the charge structure is appropriate, and will not have any obvious harmful effects on the furnace conditions; using 10.00% siderite The equivalent amount of iron ore can replace the production of low-iron powdered acidic sinter, which can produce certain economic benefits; the results of roasting and magnetic separation of poor-quality siderite show that after roasting, a larger part of the siderite can be Turn into strong magnetic minerals, and use weak magnetic separation to obtain iron concentrate with a concentrate grade of 56.07%-57.83%; use rotary kiln magnetization roasting and weak magnetic separation to process lower-grade Wangjiatan siderite The mine is technically feasible. The sorting index of 700=C roasting magnetic separation is better, the total concentrate grade is 57. 83%, the rough separation tip ore grade is 58. 86%, the yield is 58. 88%, and the recovery rate is 91. 19%. The silica content in the roasted ore is relatively high, above 31.00%, and can be reduced to less than 5.08% after sorting; the sulfur content in the roasted ore is as low as 0.190% and as high as 0.659%. After sorting, The corresponding content in the concentrate drops to a minimum of 0.068% and a maximum of 0.312%.
Chongqing University conducted experimental research on the roasting, beneficiation, sintering and metallurgical properties of Weiyuan siderite in the laboratory, and proposed various alternative utilization processes and methods for Weiyuan siderite. Weiyuan siderite has high iron content and low sulfur and phosphorus content. It is actually a composite ore of hematite and siderite rather than a single siderite. Weiyuan siderite “02” content is as high as about 26%, which is the biggest flaw of this type of ore. Research shows that after the ore is oxidized and roasted, a concentrate with high iron content and low SiO2 content can be obtained by water washing and beneficiation; if all is crushed to -6mm, after washing, drying and screening to remove the -0.8mm particle size, iron-containing ore can be obtained. For tip ores with an iron content of about 50% and a SiO2 content of at least 20%, the concentrate recovery rate can reach 70%; through reduction roasting and magnetic separation, a concentrate with an iron content of about 58% and a SiO2 content of about 10% can be obtained. Its concentrate recovery rate can reach 35% -40%; using modern magnetization roasting magnetic separation method, its mineral processing effect and economic benefits will be better; 6-30mm oxidation roasted ore has particularly good reducing properties, and the reduction degree can reach 100% The oxidized roasted ore of Weiyuan siderite has good sintering performance. Under the condition of 8% fuel ratio, the sinter has high yield, high mechanical strength and good metallurgical properties.
The scientific research team led by Academician Yu Yongfu implemented flash magnetization and burning technology on refractory and lean iron ore resources rich in siderite (including raw ore and mid-range ore), and achieved difficult-to-separate iron ore resources in seconds. Magnetization roasting process for selecting lean iron ore resources. The realization of flash magnetization roasting technology will help greatly improve the iron recovery rate of difficult-to-select weakly magnetic minerals, shorten the existing industrial production process, reduce energy consumption, and improve the utilization rate of my country’s iron ore resources.
Siderite resources are widely distributed in my country, with various types and complex compositions. In comparison, roasting and magnetic separation can significantly increase the magnetism of the product, and the iron grade can be effectively improved. Compared with strong magnetic separation and flotation, it has obvious advantages. superiority. Flash magnetization roasting and microwave roasting technology are the technical trends in siderite roasting treatment. They have the advantages of significant effects, high efficiency, and relatively economical investment costs.