Prospect of iron ore beneficiation technology development

Major breakthrough in mineral processing

At present domestic iron ore dressing plant processes mainly magnetite and hematite two categories, including magnetite concentrate production accounts for about three-quarters of China's iron ore production, and most of the domestic iron ore mine in terms of innovative mineral processing technology The main types of ore are also targeted.

I. Progress in magnetite ore dressing process

China's iron ore resources are relatively abundant, and in terms of reserves, it is second only to Russia, Canada, Australia and Brazil. 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 process”, “full magnetic separation sorting process”, “ultrafine crushing-wet magnetic separation tailing process” ".

(1) Stage grinding, weak magnetic separation-reverse flotation process

Due to the fine size of the magnetite currently selected in China, the negative impact of magnetic agglomeration in the selection is becoming more and more obvious, which makes it more and more difficult to improve the concentrate grade by a single magnetic separation method. The magnetic separation method is combined with anion reverse flotation. As a result, the complementary advantages in the process of selecting magnetite ore are conducive to improving the grade of concentrate of magnetite ore. Stage grinding, weak magnetic separation-reverse flotation process is one of the more effective processes for iron reduction and iron reduction in iron concentrates in China. Angang Steel Changling Concentrator uses a reverse cation flotation process. After a rough selection, the final concentrate and reverse flotation foam are obtained by concentrating magnetic separation, grinding, regrind the product through dewatering tank and multiple sweeps. The tailing and magnetic separation concentrates are returned to the reverse flotation operation, and the concentrate grade is increased from 64% to 68.89%. The SiO 2 content in the concentrate is reduced to less than 4%, and the iron recovery rate is over 98%. Taiyuan Jianshan Iron Mine adopts an anion reverse flotation process. After high-efficiency flotation reagents, one rough selection is selected three times. The concentrate grade is about 65.5% and the SiO 2 content is about 8%. The concentrate is obtained after transformation. The iron grade is above 68.9%, the SiO 2 content is below 4%, the recovery rate of reverse flotation operation is about 98.5%, and the physical and chemical properties of the concentrate slurry meet the requirements of long-distance pipeline transportation.

(2) 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. Mine ore concentrator belonging Shougang selected Anshan poor magnetite ore and banded gneissic structure, the metal in mineral magnetite, hematite a small amount, the whole magnetic separation process is selected from the mine Shougang The plant has been used for many years, and its iron concentrate grade has been maintained at around 67%. It has won the national championship of iron concentrate quality. 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.

(3) 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 SiO 2 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.

Second, the progress of red ore beneficiation process

China's red mineral resources are large in reserves and poorly selectable, mainly distributed in Liaoning, Hebei, Gansu, Anhui, Inner Mongolia, Henan, Hubei, Shanxi, Guizhou and other places. The easy-to-select magnetite resources in China are facing an increasingly shortage situation. The reserve magnetite mines are obviously insufficient. Most of the relatively well-selected red iron mines have entered the deep mining period, and the mining cost has increased year by year. The red ore beneficiation has always been China. A major problem in the mineral processing industry. In recent years, China's mineral processing science and technology workers have persistently carried out mineral processing and research, and developed new mineral processing chemicals, processes and equipment for the specific characteristics of red mines, which has made a major breakthrough in China's red ore beneficiation technology, and the technological indicators have reached the international advanced level.

(1) Continuous grinding--magnetic separation-flotation combined process

Anshan Iron and Steel Co., Ltd. Concentrator in the study compared the "continuous grinding, weak magnetic - strong magnetic - anion reverse flotation process", "continuous grinding, weak magnetic - strong magnetic - acid positive flotation process", "stage grinding After re-election - magnetic separation - acidic positive flotation, "continuous grinding, weak magnetic - strong magnetic - cationic reverse flotation process" and other processes, according to the experimental results, the use of "continuous grinding, weak magnetic - strong magnetic - The anion reverse flotation process, the structure of the process is reasonable and compact, and has strong adaptability to changes in ore properties and stable production. After the transformation of the Tuanjuntai concentrator according to this process, under the condition of 29.60% of the original ore grade, the index of refined ore grade is more than 67.59%, the tailings grade is 10.56%, and the metal recovery rate is 82.24%. At present, in addition to the Tuanjuntai concentrator, the Qidashan Concentrator and the Donganshan Sintering Plant have completed the technical transformation according to this process. The Sijiaying Concentrator, Wuyang Red Iron Ore Concentrator and Gongchangling Red Iron Ore Concentrator have already Construction started according to this process and significant progress was made. The Guanmenshan and Hujiamiao Red Iron Ore Dressing Plants based on this process are also under construction.

(II) Stage grinding--re-selection--magnetic separation--flotation combined process

Since 2001, Qi Dashan Concentrator has replaced the phase grinding and re-election-strong magnetic-acid positive flotation process and the second selection of the selected workshops by phase grinding and re-election-strong magnetic-anion reverse flotation process. After the roasting magnetic separation process in the workshop, the concentrate grade of the selected workshop increased from 63.60% to 66.21%, and the concentrate grade of the second selection workshop increased from 63.26% to 66.80%. At present, the entire plant has been iron concentrate since April 2004. The grade has been stable at over 67%, the grade of tailings has also dropped from the original 12.5% ​​to 11.14%, the SiO 2 has been reduced from the original 8% to less than 4%, the grade of iron concentrate has increased by 3.8 percentage points before the transformation, and the grade of tailings has decreased. 1.36 percentage points, the first-class product rate is over 99.80%. Anshan Iron and Steel Donganshan Plant also obtained the technical index of 64.49% concentrate grade and 76.11% metal recovery rate.

(3) Strong magnetic-reverse flotation-baking combined process

At present, the reduction and roasting magnetic separation process of domestic red iron ore is not widely used due to its high cost and low iron concentrate grade. The process is mainly suitable for iron ore with large burning loss such as limonite and siderite. Due to the low theoretical grade of this type of iron ore, the iron concentrate with low impurity content is obtained through strong magnetic-reverse flotation, and then the iron grade of the product can be greatly improved by ordinary roasting or production of pellets, which is still high quality. Ironmaking raw materials. According to the experimental study of the iron ore of Jiangxi Tiekeng limonite, the Maanshan Mine Research Institute shows that the iron grade of the roasting product can reach more than 65%. Compared with the combined roasting, magnetic separation and reverse flotation processes, the production cost is large. The decline has made this type of iron ore economically exploitable.

Third, major progress in mineral processing equipment

In recent years, the improvement of China's iron ore beneficiation process has been supported by new mineral processing equipment and advanced foreign equipment, especially in recent years in crushing, grinding classification, sorting (including re-election, magnetic separation, flotation, etc.) Many new high-efficiency equipments have been developed or introduced in the aspects of dewatering, filtration, etc., and have been successfully applied, providing equipment guarantee for the progress of mineral processing technology.

(1) Crushing equipment

For decades, China's metal mines have been striving to save energy and reduce consumption and improve economic efficiency. "More and less grinding" is the basic principle. The progress of the crushing equipment is mainly manifested in the development and application of a new type of external moving 颚 颚 颚jaw crusher , double cavity jaw crusher , double cavity rotary crusher, impact jaw crusher and other original, practical crushing equipment. However, there is still a certain gap between the technical and operational effects of these devices compared with the crushing devices introduced abroad. High-efficiency cone crushers from foreign companies such as Metso and Sandvik reduce the final crushing size by an average of 5 to 8 mm. The high-pressure roller press that has been developed in China to replace fine crushing and one-stage rough grinding is currently undergoing industrial tests in mines such as Maanshan Nanshan Mining Company. In addition, the current column mill has certain applications in some mines in China. This kind of equipment has a large energy saving and consumption reduction, which can increase the output of the system by 30%-50%, and the equipment operation rate is high, which has little impact on the environment.

(2) Grinding equipment

Since the ball mill is a mature device with many advantages, the research of grinding equipment is mainly focused on energy saving and mill liner. The energy saving and consumption reduction of the mill is mainly reflected in the specifications of the grinding equipment, the grinding medium, the structural performance of the equipment, the arrangement of the grinding equipment and the process flow. Development of a mill liner experienced from the metal plate (manganese steel, high chromium alloy steel, a nickel hard alloy or the like) to a non-metallic liner (rubber lining), and then to develop a magnetic liner, the magnetic liner enables The mill has the advantages of small load, long service life and low noise. The magnetic lining has been successfully applied in Benxishan Shantie Iron Mine, Anshan Qidanshan Concentrator, Baotou Steel Concentrator and other enterprises, and has achieved remarkable economic benefits. In addition, there has been some progress in the research on the automatic control of grinding and grinding aids.

(3) Fine particle screening and grading equipment

In recent years, through the continuous introduction and digestion of foreign advanced technology, China's fine-grain screening and grading equipment has reached the international level. MVS high-frequency vibrating mesh screen has been widely used in the upgrading and impurity-reducing process of iron ore concentrates in China's metallurgical mines. It has been successfully applied to mining enterprises such as Shougang Concentrator, Benxi Steel Concentrator, Anshan Iron and Steel Concentrator, and Wuhan Iron and Steel Concentrator. The production practice proves that by using the fine sieve instead of the traditional nylon fine sieve, the screening quality efficiency can be increased from less than 30% to 50% or higher, which obviously improves the efficiency of the regrinder, and improves the quality of the iron concentrate while reducing impurities. Save energy. In addition, GYX31-1207 high-frequency vibrating fine screen can also effectively improve the grade of iron concentrate. The equipment has good mechanical properties, good screening efficiency and long service life of the screen. It has been successfully in Heishan Iron Mine. application. The new oblique narrow flow grading equipment has the characteristics of large unit area capacity, high classification efficiency, high cost performance and wide application range in the grading process. It has been effectively used in the cloud tin company Huang Maoshan processing plant and lead mine in Yunnan Lan Cang.

American Derrick high-frequency fine screen has also been applied in China's magnetite concentrator. After Laiwu Mining Company and Lunan Mining Company used this fine screen instead of ordinary nylon fine screen, the processing capacity of raw ore increased by more than 25%, and the grade of concentrate increased by nearly 1%.

(4) Magnetic separation equipment

The progress of magnetic separation equipment in China is relatively fast. From weak magnetic to strong magnetic, from electromagnetic to permanent magnet, from dry to wet, people have done a lot of research work and made great progress. Horizontal magnetic separation equipment. At present, the magnetic separation equipment developed in China mainly includes: a. Wet weak magnetic separation equipment, typically including φ1050 series permanent magnet cylinder magnetic separator, LP series vertical disc permanent magnet magnetic separator, BX series new high efficiency permanent magnet magnetic separation Machine, new BK series special permanent magnet magnetic separator, YCMC series permanent magnet pulsation magnetic separator, magnetic separation column, etc.; b. permanent magnet bulk ore dry magnetic separator, representative of CTDG series permanent magnet bulk Ore dry magnetic separator; c. medium magnetic field permanent magnet cylinder magnetic separator, representative of ZC, WCT series medium magnetic permanent magnet cylinder magnetic separator. d. Strong magnetic separator, mainly CS series induction roller type strong magnetic separator, Shp series flat ring type strong magnetic separator, Slon series vertical ring pulsation high gradient strong magnetic separator, DPMS series open gradient permanent magnet strong magnetic separation Machine, YCG series coarse-grain permanent magnet roller type strong magnetic separator.

(5) Magnetic- reselection equipment

At present, the composite beneficiation technology has made great progress. The magnetic-re-selection equipment developed and applied mainly includes a magnetic separation column, a magnetic agglomeration re-selector, a low field strength self-weight jig, and a CSX series magnetic field screening machine. They are characterized by a composite force field, in addition to magnetic force, gravity and hydrodynamics, which is a combination of magnetic separation and re-election. The various forces play a complementary role, thus increasing the selectivity of sorting. These devices are now used in actual production, and magnetic separation columns and magnetic agglomeration re-selectors are widely used.

Bengang Nanfen and Shantoushan Concentrator use magnetic separation column to improve the quality of the magnet concentrate. The iron grade of the concentrate can be increased to over 69%, and the SiO 2 content in the concentrate is reduced to less than 4%. The rate reached 98.57%. The Tonggang Shipu Iron Ore Concentrator uses 8 ∮600 magnetic separation columns to increase the concentrate grade from 65.5% to 67.48%. Baotou Steel Concentrator uses magnetic separation column to treat industrial analysis of weak magnetic separation concentrate. The concentrate grade increased from 61% to 65% and the SiO 2 content decreased from 3.5% to 2.13%.

The Taigang Shoukou Iron Ore Concentrator uses a variable-diameter magnetic concentrator to treat the northern ore with a very fine grain size. The grade of iron concentrate is increased from 63.88% to 66.01%. The research results of the Shougang Waterworks Concentrator using electromagnetic gathering machine instead of the ordinary permanent magnet magnetic gathering machine prove that the iron concentrate grade can be increased by more than 2 percentage points, and it also indicates that the coarse particle size can be selected.

(6) Flotation equipment

Flotation equipment is widely used in iron ore beneficiation operations. At present, the flotation equipment widely used in China is mainly various types of flotation machines, and the types are self-aspirating mechanical agitating type, pneumatic mechanical stirring type and inflatable type. The research on the flotation machine mainly focuses on the flotation machine tank structure, impeller shape, impeller speed, impeller diameter, stator and so on. The use of teaching more includes XT series flotation machine, BF series flotation machine, JJF series flotation machine, CF series flotation machine, etc. In recent years, the new type mainly has XTB rod flotation machine, and fine grain downstream flotation Separation machine and XPM type jet flotation machine. In addition, the original is widely used in the coal industry flotation column, Chinese Academy of Sciences academician Yu Yongfu first time in China will be the most advanced micro-bubble-type "flotation column" successfully applied to iron ore cation, recently conducted a successful Anshan Iron and Steel Company The industrial test not only greatly simplifies the process, but also the selected iron ore is more pure.

(7) Filtration and dewatering equipment

In recent years, there have been major breakthroughs in filtration and dewatering equipment. The new filtration and dewatering equipment mainly includes disc vacuum filter, filter press and ceramic filter. The latest research and development also includes membrane filtration technology. The disc vacuum filter is optimized for the characteristics of high density, fast sedimentation speed and high viscosity of metal minerals. The utility model has the advantages of firm and reasonable structure, stable operation of the filter disc, strong automatic stirring of the speed regulation, reliable sealing of the shaft end, and no leakage of the slurry. At present, more than 300 disc filters of nearly 100 concentrating plants have replaced the original filters, and the filtration index has been significantly improved. The ceramic filter uses the micropores on the ceramic plate to produce capillary action. Under the condition of no external force, the liquid enters the micropores of the ceramic plate by capillary action, and under the negative pressure generated by the vacuum pump, the solid and the liquid are separated. purpose. The ceramic filter used in the Donganshan concentrator of Anshan Iron and Steel Co., Ltd. showed that the filtration equipment coefficient was increased from 0.227t/(m 2 .h) to 0.757t/(m 2 .h) compared with the barrel internal filter. The filter cake moisture was 13.48% fell to 9.41%. At present, the Donganshan Concentrator has replaced the original cartridge internal filter with 50% of ceramic and disc filter equipment.

Fourth, the mineral processing agent is constantly updated

The progress of mineral processing pharmacy has played an important role in the development of China's iron ore beneficiation process, especially the development of iron and silicon reduction. Domestically developed iron ore flotation reagents mainly include collectors and inhibitors, and collectors are divided into three categories: anion collectors, cation collectors, and chelate collectors.

In recent years, China's mineral processing workers have mainly modified and mixed fatty acids and petroleum sulfonates, which have significantly improved their selectivity and enhanced their ability to capture, especially in the case of anion reverse flotation collectors. progress. The new high-efficiency anion collectors SH-37, MZ-21 and RA-515 have been successfully applied in the red iron ore dressing plant of Anshan Iron and Steel Plant Selection Plant, Qi Dashan Plant and Donganshan Sintering Plant respectively. Iron concentrate grade It has reached 66%~67%, and the cost of ton concentrates has been reduced by more than 15%. The adaptability to temperature has been enhanced and the economic benefits are remarkable. The new high-efficiency collectors MD-28 and MH-80 for the upgrading of magnetite concentrates have been promoted and applied in Lunan Mining Company and Taishan Jianshan Iron Mine, respectively, and the grade of magnet concentrate has increased to over 69%. The newly developed MH-88 special effect collector is used to select the poor iron ore from the Wuyang Temple in Wuyang, and obtains a good indicator of the iron concentrate grade of more than 65% and the metal recovery rate of 72.56%.

Cationic collectors are primarily amine collectors for the flotation of siliceous minerals, including fatty amines and ether amines. There are not many concentrating plants using amine collectors in China, and there are few kinds of pesticides, mainly based on 12-carbon fatty amines and mixed amines. Angang Steel Gongchangling Plant adopted a new cationic collector YS-73. In addition, the new cationic collector GE-601 developed by Wuhan University of Technology has the characteristics of low temperature resistance and high efficiency, which can not only solve the problem of dodecylamine, but also can directly throw tail by magnetic tailing. Streamline the process.

The chelate collector forms a stable chelate with metal ions on the surface of the mineral, and its selectivity is significantly higher than that of the fatty acid collector. For example, water-soluble carboxymethyl starch is used in industrial production in Anshan Iron and Steel Plant Selection Plant, which greatly simplifies the preparation process of the medicament and reduces the production cost. The annual benefit is more than 3 million yuan. The iron ore desulfurization special activator MHH-1 has obvious effects on the removal of sulfide ore in iron concentrate, especially pyrrhotite with strong magnetic properties and poor floatability. Compared with other activators, MHH-1 It has the characteristics of low dosage, low cost and obvious desulfurization effect. At present, the product has been successfully applied in many mines. Therefore, the development of this product provides a new way for iron concentrate to reduce iron and reduce sulfur.

V. Development direction of China's iron ore beneficiation technology

Although some ore processing technology and concentrate quality of iron ore in China have reached the international advanced level, the characteristics of iron ore in China are poor, miscellaneous, fine and various, and the new requirements of iron and steel industry for iron concentrates have been proposed to Chinese mineral processing workers. New challenges. Therefore, China's metallurgical mine beneficiation technology has a deeper development:

(1) While promoting the application of high-quality iron concentrate beneficiation technology represented by magnetic separation-reverse flotation and high-efficiency magnetic separation (magnetic re-election), the beneficiation process should be as efficient and simple as possible, so it should be strengthened. Research on mineral processing equipment and beneficiation process to achieve the best results in the most appropriate process. The reverse flotation process has important application prospects for improving the recovery rate of metals, and research on reverse flotation reagents should be actively strengthened.

(2) While continuing to pay attention to the technology of iron reduction and iron reduction in iron concentrates, we should pay attention to the research of other harmful impurities technologies, including S, P, K, Na, F, etc. in the future.

(3) Research on the fine-layered red iron ore and composite polymetallic red iron ore beneficiation technology should be further strengthened to further improve the utilization rate of lean red iron ore in China.

(4) In the aspect of grinding and sorting equipment, in the future, we should do a good job in the introduction and cooperative development of energy-saving superfine crushing equipment. We should increase the introduction and digestion of foreign advanced technology and equipment, and improve the overall technical equipment level of China's iron ore as soon as possible. . At the same time, we will consider the development and research work of the coarse-grain tailing process and related equipment. The development of energy-saving beneficiation equipment capable of effectively recovering fine-grained iron minerals should be further strengthened, including permanent magnetization of strong magnetic equipment, fine-grain flotation machine and flotation column. More in-depth study of multi-cylinder magnetic separators with multi-segment selection performance.

(5) In the aspect of mineral processing chemicals, emphasis should be placed on the development of agents that are adaptable to various ores, high-efficiency, low-temperature-resistant, and non-toxic; research on simultaneous preparation and simultaneous addition of pharmaceutical agents; High-efficiency collector for quartz silicate-like gangue minerals and application range for expanding reverse flotation process.

(6) The current research on flotation equipment is mainly to the direction of large-scale and energy-saving, the lower limit of flotation granularity is reduced, and the composite force field is introduced into the flotation machine. In addition, the automatic control of the flotation machine should also be strengthened. the study. There is still a lot of work to be done on the application of flotation columns in iron ore mines, which has great prospects.

(7) In the aspect of filtration and dewatering equipment: 1 research and development of high-efficiency filter media; 2 development of multi-functional integrated components to enhance sealing; 3 development of composite filtration technology equipment; 4 equipment large-scale, energy-saving and automation.

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