With China's rapid economic development, the domestic demand for iron ore increasing in recent years, substantial growth in iron ore imports in 2000, imports of 69.97 million t, in 2002 increased to 111 million t, 2004 reached 2.08 billion tons. To a certain extent, this has caused a surge in iron ore prices worldwide, resulting in a large loss of foreign exchange. Under this circumstance, it is very important to study the development progress of iron ore beneficiation technology at home and abroad, and make good use of the existing domestic mineral resources to effectively suppress the price increase of iron ore and promote the sustained, healthy and stable development of the national economy.
The vast majority of China's iron ore is lean iron ore, accounting for 97.5% of the total reserves. Among them, 48.8% of magnetite, 20.8% of vanadium- titanium magnetite, 20.8% of hematite, 3.5% of mixed ore (magnetic-red, magnetic-Ling, Chi-Rendrite symbiotic ore), and 3.7% of siderite. Limonite is 2.4%. The average grade of ore is 32.67%, which is 11 percentage points lower than the average grade of world iron ore. Due to the low quality of domestic iron concentrate, it not only seriously affects the sales and sustainable development of iron concentrates in China, but also affects the production cost and economic benefits of blast furnaces. Therefore, China should also actively research and develop iron concentrates for counter-floating deep selection and grading de-sludge. New equipment such as new processes and large flotation columns, large-volume wear-resistant high-frequency vibrating fine screens and new composite force field sorting machines. High-grade, low-SiO 2 and other iron concentrates are produced from low-grade, high-SiO 2 magnetic iron shale to meet the needs of the development of China's steel industry. This paper briefly reviews the research and application of new technologies and equipment for iron ore beneficiation in China in recent years.
I. Research and application of new equipment for mineral processing
(1) New high-efficiency SLon vertical ring pulsation high gradient magnetic separator
In 1988, the first SLon21500 strong magnetic separator (mesh sorting medium) was selected for fine-grained hematite in Magang Gushan Concentrator, and achieved good technical indicators. The strong magnetic separator is in structure and sorting medium. In many aspects, the improvement has been made, from the network medium to the rod medium, which has made breakthroughs in the selection and maintenance of sorting. From the end of 2001 to 2002, the first and second workshops of Qidashan Concentrator were used in the stage grinding 2 classification 2 coarse grain re-election 2 fine grain weak magnetic 2 strong magnetic 2 reverse flotation process using SLon21750 strong magnetic separator 10 sets, all The technical indicators of the process are: 30.15% of the original ore grade, 67% of the iron concentrate grade, and a recovery rate of 75.86%. See Table 1.
Table 1 SLon21500 strong magnetic separator (2mm rod media) and on-site production
Comparison of SHP22000 Strong Magnetic Separator Sorting Index
At present, Panzhihua Titanium Plant uses 10 SLon21500 strong magnetic separators when recovering -45Lm ilmenite; Magang Gushan Hematite ore dressing plant uses 6 SLon21750 and 4 SLon21500 beneficiation to recover fine-grained hematite; Meishan uses 18 Taiwan SLon21500; Anshan Iron and Steel Donganshan Concentrator uses 10 SLon21750, a total of 60 in the concentrator.
(2) Magnetic separation column 2 electromagnetic pulsation low-weak magnetic field magnetic weight concentrator This equipment adopts sequential alternating power excitation mechanism, and the magnetic field force is shifted under the pulsation sequence in the sorting chamber, and the high-speed rising water flow is introduced from the lower part of the sorting chamber, and the rising water flow The upward rushing force and the downward magnetic force exert two opposite forces on the slurry, so that the monolithic magnetite particles and the fused-rich body are subjected to continuous downward magnetic force and magnetic agglomeration and magnetic chain gravity. To the bottom cone discharge port, become a high-grade magnetite concentrate. The slime, monomeric gangue, magnetite and gangue depleted organisms are discharged into the tailings from the overflow. The magnetic separation column tailings are mainly connected to the ore body and need to be reground. Again, the test results are shown in Table 2.
Table 2 Selected experimental results of medium and low grade magnetite concentrate in magnetic separation column (%)
The sorting principle of the machine and the magnetic condenser used in the Anshan-type magnetite quartzite and the magnetic 2-weight concentrator developed by Russia in the early 1990s in the Shougang Mining Company Waterworks and Dashihe Concentrator in the late 1980s The selection principle is similar. Both of the magnetite concentrates milled in 2 to 3 stages are used to remove the coarse-grained ferrosilicon continuous body, improve the iron grade of the magnetite concentrate and reduce the SiO 2 content. Since 1994, the machine has been applied in more than ten ore dressing plants such as Tongshishigou Iron Mine and Jilin Sifangshan, with good results.
Second, the research and application of new mineral processing technology
After China's accession to the WTO, in order to survive and develop in the market competition, the iron and steel blast furnaces have higher and higher requirements for the furnace charge. The ore dressing plant uses the reverse flotation process for deep selection of re-elected or magnetically selected iron concentrates, and the technical indicators for sorting are greatly improved.
(1) Significant progress in hematite beneficiation technology
Hematite is an important iron ore resource in China and one of the main types of difficult ore in China. In recent years, with the successful development and application of new processes, new equipment and new pharmaceuticals, hematite mineral processing technology has made major breakthroughs.
Anshan Iron and Steel Station Concentrator is the key construction project of the National “Eighth Five-Year Plan†with a design scale of 9 million t/a. The plant is the first in China to adopt the continuous grinding-weakening magnetic-strong magnetic-anion reverse flotation process. Once completed and put into production, once the process is put into production, it shows the huge advantage of the reverse flotation process in improving silicon and reducing silicon. Efficient beneficiation agents also play a key role. At present, the ore dressing technical indicators of the plant are: 29.86% of iron ore, 67.53% of iron concentrate grade, 6% of SiO 2 and 82.24% of iron recovery.
Anshan Qidashan Concentrator, processing 8 million tons of iron oxide ore containing 30% iron. The process flow before 2001 is: 75~25mm into the second-selection workshop for reduction roasting magnetic separation process, 20~0mm into the first-stage workshop stage grinding coarse subdivision selection, coarse re-election (spiral chute) 2 fine-grain magnetic separation (strong and weak magnetic separator) 2 petroleum sulfonate acidic flotation. The technical indicators are: the original ore contains 28.49%, the iron concentrate contains 63.60%, SiO 2 >10%, the tailings contain 11.36%, and the iron recovery rate is 73.20%. In 2001, both workshops were based on anion reverse flotation technology as the core of “stage grinding, coarse subdivision, coarse re-election (spiral chute) 2 fine-grain magnetic separation (weak magnetic, strong magnetic separation) 2 anion anti-floating The process was selected for transformation. From 2003-01 to July, the technical index was 29.64% of the ore containing iron, the concentrate containing 67.56%, the SiO2 was reduced to 4.5%, the tailings containing 10.67%, and the process transformation was quite successful [3] It basically meets the requirements of Anshan Iron and Steel Company for the mineral processing technical indicators of its iron ore mines, and partially exceeds the foreign iron ore dressing technical indicators of the same type.
(2) Magnetite ore dressing technology has reached a new level
Magnetite ore dressing is the main body of iron ore beneficiation, accounting for more than 70% of domestic iron concentrate production. Since the beginning of the 21st century, with the development of the steel industry, the requirements for raw materials are getting higher and higher. In order to meet this requirement, many units and mines have done a lot of research and development work around “lifting iron and reducing siliconâ€. On this basis, different technical solutions have been adopted to carry out technical transformation of the concentrator, and remarkable results have been achieved. Technology has reached a new level [4] .
1, Anshan magnet quartz rock ore. Angang Steel Changling Mining Company's concentrator treats 9.5 million tons of ore annually. The production process before 2001 is stage grinding, single magnetic separation, fine screening and regrind process. The fine iron screen has an iron grade of 64.5% and a particle size of -74μm. 90%, the iron concentrate grade after filtration is 65.55%, and SiO 2 is 8.31%. In order to expand the living space and maintain sustainable development, the company carried out a cationic reverse flotation test with fine mesh sieved iron concentrate as raw material. In 2001-December and 2002-2008, the first and second flotation workshops were rebuilt and put into production. By the end of 2002, the grade of iron concentrate after the transformation reached 68.89% on average, SiO 2 decreased to 4.09%, flotation tailings contained 10% to 12% of iron, flotation concentrate operation rate was 92%, and iron operation recovery rate was 98.5%. The quality of iron concentrate has reached the international advanced level. The process is characterized in that only one cationic amine salt is used as a collector, and the type and system of the medicament are simple and low in cost. The low temperature of the flotation slurry (only 15 to 17 ° C) is significant for reducing the production cost of the Gongchangling Concentrator in the high and cold zone. Taiyuan Jianshan Concentrator and Shandong Laigang Hanwang Concentrator also carried out anion reverse flotation reform. The experimental results show that the technical indicators are good [1 , 5] .
2. High temperature hydrothermal skarn magnet ore. Wuhan Jinshan store magnetite, use of weak magnetic separation - Floating sulfur - fine sieve - magnetic separation process, the iron ore grade increased to more than 67.5%, SiO 2 to 3% or less, sulfur, 0.07% to 0.05% At present, the production process is being transformed. The WISCO Daye Iron Mine carried out an experimental study on iron reduction and silicon reduction. The test iron concentrate grade was 64%, sulfur was about 0.4%, and the industrial production process was being reformed.
(III) Significant progress in comprehensive recycling of multi-metal iron ore
Type of multi-metallic ore mainly Baiyun'ebo rare earth-containing iron and other metal associated, Vanadium and titanium magnetite and in Daye, Jinling, Lu copper-containing magnetite. Over the years, many research, design and colleges and universities in China have carried out a lot of research work on multi-metal iron ore, and achieved technological breakthroughs in many aspects, and successfully applied to industrial production, making great progress in multi-metal iron ore beneficiation technology. [7] .
Baiyunebo ore is iron, niobium and rare earth-based multi-metal deposits in symbiosis. The ore is divided into two types: magnetite and oxidized ore. In the 1970s, Baotou Steel Concentrator used weak magnetic separation iron-flotation rare earth-strong magnetic separation iron and roasting 2 magnetic separation to treat oxidized ore, and the production index was poor. In 1986, Baotou Steel cooperated with Changsha Research Institute of Mining and Metallurgy, and adopted a weak magnetic-strong magnetic-flotation process. By 1993, all the oxidized ore series of the ore dressing plant was transformed according to this process, and good indicators and effects were obtained. The iron concentrate grade was 60%～61%, fluorine 0.78%, phosphorus 0.12%, iron recovery rate 71%～73%; rare earth concentrate grade ReO 50%～60% (recovery rate 12.55%), rare earth mineral grade ReO 34.5% (recycling 6.01%), the total recovery rate of rare earth is 18.56% [8] . Industrial trials for the recovery of rare earths from magnetite systems have recently been successful, producing ReO 45% to 50% rare earth concentrates. At present, the rare earth concentrate is produced from the iron-rare earth beneficiation process. According to the rare earth oxide, the actual annual output reaches 60,000 tons, accounting for more than 70% of the national output. Baotou Steel Concentrator uses a weak magnetic-strong magnetic-flotation process to comprehensively recover iron and rare earth. It solves the dolomite ore dressing technology and significantly improves the new process of iron and rare earth.
Panzhihua vanadium-titanium magnetite reserves account for 87% of China's total vanadium-titanium magnetite reserves. Its main useful minerals are vanadium titano-magnetite and ilmenite. The design scale of the Midi Concentrator, built in 1978, was 13.5 million t/a, and the vanadium-titanium magnetite was recovered by a single weak magnetic separation. In 1979, a titanium plant with a capacity of 50,000 t/a (titanium concentrate) was built to treat the iron ore tailings of the densely concentrating plant. In 1990, the titanium plant was expanded to a scale of 100,000 t/a. The process has been modified several times to form a beneficiation tailings with a particle size of 0.045mm, and a +0.045mm re-election-strong magnetic-desulfurization flotation-electrical separation process to obtain a coarse titanium concentrate with a TiO 2 content of 47% or more; -0.045mm particle size In part, the selection process of strong magnetic-desulfurization flotation-ilmenite flotation is carried out, and the grade of fine-grained titanium concentrate is 47.3%~48%, which can make the titanium plant produce 30,000-50,000 per year of titanium concentrate. t. At present, the titanium indicator and output of Panzhihua Titanium Industry Co., Ltd. are shown in Table 3 [9] .
Table 3 Titanium index and output of Panzhihua Titanium Company
Third, the proposal
1. Targeted research on fine-grained refractory weak magnetic iron ore beneficiation process, including some mines that have been produced but have insufficient indicators and new mines to be developed to improve the technical and economic indicators of old mine production and meet new mines. Construction needs.
2. Although China's iron ore resources are limited, it is necessary to import a large number of foreign high-quality iron ore. However, it must be recognized that domestic iron ore still has a capacity of 200 million to 250 million tons per year, which can be used to produce 60 to 70 million tons of iron ore raw materials. Therefore, we will strengthen the progress of iron ore beneficiation technology in China and further strengthen the iron drop. Silicon research work to improve the quality of iron concentrate is crucial to the improvement of the overall efficiency of China's steel industry.
3. Continue to carry out research on new processes, new equipment, new pharmaceuticals and new materials, further improve the equipment level of the concentrator, improve process indicators, reduce energy consumption, thereby reducing ore production costs and enhancing competitiveness.
4. Make full use of China's iron ore resources. While improving the grade of concentrates, we must pay attention not to reduce or reduce the recovery rate indicators, and further improve the comprehensive utilization of resources.
5. The use of flotation columns in iron concentrate anti-flotation has many advantages over traditional flotation machines. However, the current anti-flotation of iron concentrates in China has not carried out research and industrial application of flotation columns. It can strengthen research and application in industrial production, improve the effect of anti-flotation and silicon reduction, and improve the recovery rate of iron concentrate.
references
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[2] Li Weibing et al. Research Status and Development Direction of Red Iron Ore Dressing Technology in China [J]. Metal Mines, 2005 (3) .
[3] Li Weibing. Analysis and Suggestions on the Problems Existing in the Production Process of Qidashan Iron Ore Dressing Plant [J]. Foreign Metal Mines, 2002 (6) .
[4] Liu Dong. Improvement and suggestion of iron reduction and silicon reduction process for iron concentrate [J]. Mining Engineering, 2003 (2 ~ 3) .
[5] Chen Zhanjin et al. Zoujie Angang iron concentrate iron lifting and silicon reduction work
[6] Liu Zhengguo. Comprehensive research on iron selection from sintering ironmaking [J]. Mining Express, 2003.4.
[7] Yan Hongquan. Review and Prospect of Baiyun Ebo Mineral Processing Technology [J]. Mining Engineering, 2003 (1).
[8] Yu Yongfu. Practice of the pilot production of the new technology of magnetic flotation in the middle and lean oxidized ore processing plant of Baotou Steel Concentrator [J]. Mining Engineering, 1992 (1).
[9] Zhang Guanglie. Progress in China's iron ore beneficiation technology [C]. Exchange materials of the 10th National Conference on Powder Engineering Annual Conference, 2004.11.
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