The total iron ore reserves in my country are about 46.232 billion tons (excluding Taiwan Province), of which the reserves above grade C are about 22.03 billion tons [1, 2], accounting for about 17.86% of the world's total reserves. The characteristics of my country's iron ore are: (1) There are many lean ore and few rich ore. The average grade of the ore is low, with lean ore accounting for 97.5% of the total reserves and only 2.5% of the rich ore entering the furnace. (2) The types of ore are complex, with many oxidized ore, polymetallic symbiotic ore and refractory ore, and the embedded granularity is fine. Therefore, almost all the mined ores need to be processed to improve the grade of smelting raw materials and the degree of comprehensive utilization of useful ingredients. In the 21st century, mineral resources, as an important national strategic resource, as an important basic raw material for social and economic development, play a pivotal role in the construction of the national economy and the construction of national defense science and technology. With the rapid growth of my country's iron and steel production, the demand for iron raw materials for blast furnace smelting has greatly increased, and the requirements for quality have become higher and higher. Iron ore mines are faced with huge opportunities and challenges and should do a lot. However, the grade of domestic iron ore is getting lower and lower, and blast furnace ironmaking has stricter and stricter requirements on the grade of iron ore, and foreign high-quality iron ore is continuously imported. Strongly impact the domestic iron ore market. In order to survive in this general situation, iron ore can only strengthen its own technological transformation, contact the actual situation of the mine in terms of mine management, mining technology, etc., continue to explore, and actively cooperate with universities and research institutes to strengthen new technologies. Development and application.

Fortunately, in recent years, under the active efforts of our country’s mineral processing workers, we have continued to explore, innovate, actively explore, seize opportunities, and dare to challenge. Development has supported the development of national economic construction.

1. A major breakthrough has been made in the beneficiation process

At present, the iron ore processed by domestic concentrators mainly includes magnetite and hematite. The output of magnetite concentrate accounts for about 3/4 of my country’s iron concentrate output, and most of the domestic iron ore mines are undergoing technological innovation in beneficiation. The two types of ores are also mainly targeted.

1.1 Progress in the beneficiation process of magnetite ore

my country's iron ore resources are relatively rich, second only to countries such as Russia, Canada, Australia and Brazil in terms of reserves [3]. Among the iron ore resources, Anshan-type iron ore is the most widely distributed and is the most important iron ore deposit in my country. Its reserves account for more than half of the country’s total iron ore reserves, and its scale is generally relatively large. Its ore type is magnetite Mainly, it is the main type of ore selected by domestic iron ore concentrators. The more successful new processes that have emerged in recent years are representative of: "stage grinding, weak magnetic separation-reverse flotation process", "full magnetic separation process", "superfine crushing-wet magnetic separation tailing process" ".

1.1.1 Stage grinding, weak magnetic separation-reverse flotation process

Due to the fine particle size of the magnetite currently selected in my country, the negative impact of magnetic agglomeration in the separation has become increasingly obvious, making it more and more difficult to rely on a single magnetic separation method to improve the concentrate grade. Combining the magnetic separation method with anion reverse flotation To achieve the complementary advantages in the process of separating magnetite, it is beneficial to improve the grade of magnetite concentrate. The stage grinding, weak magnetic separation-reverse flotation process is one of the more effective processes for improving iron and reducing silicon in iron concentrates in my country. The Gongchangling Concentrator of Anshan Iron and Steel Co., Ltd. adopts the cationic reverse flotation process. The final concentrate is obtained through one roughing and one selection. The reverse flotation foam is concentrated and magnetically separated and then ground. The re-grinded product is subjected to dehydration tank and multiple sweep magnetic separation. The tailings and magnetic separation concentrates are returned to the reverse flotation operation for re-election. The iron grade of the concentrate is increased from 64% to 68.89%, the SiO2 content in the concentrate drops to below 4%, and the iron recovery rate is above 98%. Taigang Jianshan Iron Mine adopts anion reverse flotation process, with high-efficiency flotation reagents for one roughing, one selection and three sweeping. Before the transformation, the grade of the concentrate is about 65.5%, and the content of SiO2 is about 8%. After the transformation, the iron concentrate is obtained. The grade is above 68.9%, the SiO2 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.

1.1.2 Full magnetic separation process

The full magnetic separation process is based on the existing stage grinding, weak magnetic separation-fine sieve regrind and reselection process flow, and then use high-efficiency fine sieve and high-efficiency magnetic separation equipment for selection. Compared with the reverse flotation process, the process flow is simple, the process is reliable, the investment is low, the construction period is short, and the operation is easy. The ore selected by the Shougang Mine Concentrator belongs to the Anshan-style lean magnetite. The ore is in a banded and gneissic structure. The metal mineral is mainly magnetite, with a small amount of hematite. The full magnetic separation process is in the Shougang Mine Concentrator. After many years of application, its iron concentrate grade has been maintained at about 67%, and it has won the national champion of iron concentrate quality [6]. The domestic full magnetic separation process with high-frequency vibrating screen, BX magnetic separator, magnetic separation column, disc filter, etc. as the main equipment was first adopted in Bengang Nanfen Concentrator and Waitoushan Concentrator. The entry point of this process is accurate. , There are few openings, which is both reasonable and economical for optimizing the overall process flow and achieving the ultimate goal of reducing silicon and increasing iron. The application results show that the iron grade of the concentrate can be increased to about 69.5%, the SiO2 content in the concentrate drops to below 4%, the tailings grade and metal recovery rate remain basically unchanged, and the new processing cost is less than 20 yuan/t.

1.1.3 Superfine crushing-wet magnetic separation and polishing process

The process is to finely crush the ore to 5mm or less than 3mm, and then use a permanent magnet mid-field strength magnetic separator for wet magnetic separation and throwing. This process is of great significance for energy saving and consumption reduction, effective utilization of extremely poor iron ore and improvement of the quality of final iron ore concentrate. In order to develop and utilize iron ore with a grade of less than 20%, the Gaocun Iron Mine of Maanshan Iron & Steel Co., Ltd. used a high-pressure roller mill to finely crush the ore to less than 3mm. The medium field strength wet magnetic separation removed about 40% of the coarse-grained tailings. The iron grade of iron ore is increased to about 40%, and the final iron concentrate is obtained after regrinding and re-selection. The final iron concentrate grade of this process is above 65%, the SiO2 content is reduced to below 4%, and the tailing grade is below 10%. In addition, Shandong Laiwu Iron Mine, Jinling Iron Mine, etc. adopt the hammer crusher-wet permanent magnetic midfield strength magnetic separation process. The particle size of the selected materials is -5mm, accounting for more than 80%, and the yield rate can be 30%-40%. Of coarse-grained tailings.

1.2 The progress of red ore beneficiation technology

my country's red ore resources have large reserves and poor selectivity, mainly distributed in Liaoning, Hebei, Gansu, Anhui, Inner Mongolia, Henan, Hubei, Shanxi, Guizhou and other places. The domestic easily beneficiated magnetite resources are facing an increasing shortage. The reserve magnetite mines are obviously insufficient. Most of the relatively well-selected red iron ore mines have entered the period of deep mining, and the mining cost has been increasing year by year. Red ore beneficiation has always been our country. A big problem in the beneficiation industry. In recent years, our country's beneficiation scientific and technological workers have been unremittingly researching on beneficiation, and developed new beneficiation reagents, processes and equipment based on the specific characteristics of red ore. This has made my country's red ore beneficiation technology a major breakthrough, and the process and technical indicators have reached the international advanced level.

1.2.1 Continuous grinding-magnetic separation-flotation combined process

Angang Diaojuntai Concentrator has studied and compared "continuous grinding, weak magnetic-strong magnetic-anion reverse flotation process", "continuous grinding, weak magnetic-strong magnetic-acid positive flotation process", and "stage grinding" After the process of gravity separation-magnetic separation-acid positive flotation", "continuous grinding, weak magnetic-strong magnetic-cationic reverse flotation process" and other processes, according to the experimental results, it is determined to adopt "continuous grinding, weak magnetic-strong magnetic" "Anion reverse flotation process", which has a reasonable and compact structure, strong adaptability to changes in ore properties, and stable production. After the Diaojuntai Concentrator was transformed according to this process, under the condition of 29.60% of the original ore grade, it achieved the index of 67.59% or more of concentrate grade, 10.56% of tailings and 82.24% of metal recovery rate. At present, in addition to the Diaojuntai 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 Concentrator have been Construction began according to this process, and significant progress has been made. Guanmenshan and Hujiamiao red iron ore beneficiation plants based on this process are also under planning and construction.

1.2.2 Combined process of stage grinding-gravity separation-magnetic separation-flotation

Since 2001, the Qidashan Concentrator has adopted the stage grinding, gravity separation-strong magnetic-anion reverse flotation process to replace the stage grinding, gravity separation-strong magnetic-acid positive flotation process and the second separation in the first separation workshop. After the roasting and magnetic separation process in the workshop, the grade of concentrate in the first concentrator increased from 63.60% to 66.21%, and the grade in the second concentrator increased from 63.26% to 66.80%. At present, the entire concentrator started iron ore concentrate in April 2004. The grade has been stable at more than 67%, the tailings grade has dropped from 12.5% ​​to 11.14%, and SiO2 has dropped from 8% to below 4%. The iron concentrate grade has increased by 3.8% compared to before the transformation, and the tailings grade has dropped by 1.36. Percentage points, the first-class product rate is over 99.80%. Anshan Iron and Steel's Donganshan Concentrator also adopted this process to obtain technical indicators of 64.49% concentrate grade and 76.11% metal recovery rate.

1.2.3 The combined process of strong magnetic-reverse flotation-roasting

At present, the domestic red iron ore reduction roasting magnetic separation process is not widely used due to its high cost and low iron ore grade. This process is mainly suitable for limonite, siderite and other iron ore with large burning loss. Due to the low theoretical grade of this type of iron ore, firstly obtain iron concentrate with low impurity content through strong magnetic-reverse flotation, and then through ordinary roasting or production of pellets, the iron grade of the product can be greatly improved, and it is still of high quality. Raw materials for ironmaking. The test results of Maanshan Mine Research Institute on Jiangxi Tiekeng Limonite and other iron ore show that the iron grade of roasted products can reach more than 65%. Compared with the combined process of roasting, magnetic separation and reverse flotation, the production cost is substantial. Decline, so that this type of iron ore has economic exploitation value.

2. Significant progress has been made in mineral processing equipment

In recent years, the improvement of the level of iron ore beneficiation technology in my country has been supported by new types of beneficiation equipment and advanced foreign equipment, especially in recent years in crushing, grinding, classification, and separation (including gravity separation, magnetic separation, flotation, etc.), Many new high-efficiency equipment has been developed or introduced in dewatering and filtration, and has been successfully applied, which provides equipment guarantee for the advancement of mineral processing technology.

2.1 Crushing equipment

For decades, my country's metal mines have been working hard to save energy, reduce consumption, and improve economic efficiency. The basic principle is "more crushing and less grinding". The progress of crushing equipment is mainly manifested in the development and application of innovative and practical crushing equipment such as new external movable jaw even-swing jaw crusher, dual-cavity jaw crusher, dual-cavity rotary crusher, and impact jaw crusher. However, there is still a certain gap between these equipment in terms of technology and use effect compared with the crushing equipment introduced from abroad. The high-efficiency cone crushers of foreign companies such as Metso and Sandvik reduce the final crushing particle size by an average of 5-8mm. The domestically developed high-pressure roller press that can replace fine crushing and one-stage coarse grinding is currently undergoing industrial trials in mines such as Maanshan Iron and Steel Nanshan Mining Company. In addition, the current column mill is also used in some domestic mines. This type of equipment has a large energy saving and consumption reduction range, which can increase the output of the system by more than 30%-50%, and the equipment has a high operating rate and has a small impact on the environment.

2.2 Grinding equipment

Because the ball mill is a mature equipment with many advantages, the research on grinding equipment is mainly focused on energy saving and mill lining. The energy saving and consumption reduction of the mill is mainly reflected in the specifications of the grinding equipment, the grinding medium, the structure and performance of the equipment, and the configuration of the grinding equipment and process flow. The development of mill liners has gone from metal liners (manganese steel, high chromium alloy steel, hard nickel alloys, etc.) to non-metal liners (rubber liners), and then to magnetic liners [7], using magnetic liners The plate can make the mill load small, long service life, low noise, etc., magnetic liner has been successfully applied in Benxi Iron and Steel's Waitoushan Iron Mine, Anshan Iron and Steel's Qidashan Concentrator, Baotou Iron and Steel Concentrator and other enterprises, and achieved remarkable economic benefit. In addition, the research on automatic control of grinding and grinding aids has also made certain progress.

2.3 Fine particle screening and classification equipment

In recent years, through the continuous introduction and digestion of foreign advanced technology, my country's fine-grain screening and grading equipment has reached the international level. MVS high-frequency vibrating screen has been widely used in the iron concentrate quality reduction process of my country's metallurgical mines. It has been successfully used in the Shougang Concentrator, Benxi Iron and Steel Concentrator, Anshan Iron and Steel Concentrator, Wuhan Iron and Steel Concentrator and other mining enterprises. Production practice has proved that using this fine sieve to replace the traditional nylon fine sieve, the screening efficiency can be increased from less than 30% to 50% or higher, which significantly improves the efficiency of the remill, and improves the quality of the iron concentrate while reducing impurities. Save energy consumption. In addition, GYX31-1207 high-frequency vibrating fine screen can also effectively improve the grade of iron ore concentrate. The equipment has good mechanical performance, good screening efficiency, and long service life of the screen. At present, it has been successful in Heishan Iron Mine. application. The new oblique narrow flow classification equipment has the characteristics of large production capacity per unit area, high classification efficiency, high cost performance, and wide application range in the classification process. At present, it has been effectively used in the Huangmaoshan Concentrator of Yunxi Company and Yunnan Cancang Lead Mine.

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

2.4 Magnetic separation equipment

The development of magnetic separation equipment in my country is relatively fast. From weak magnetic to strong magnetic, from electromagnetic to permanent magnet, from dry to wet, etc., 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 magnetic drum type magnetic separator, LP series vertical disk permanent magnetic separator, and BX series of new high-efficiency permanent magnetic separators Machine, new BK series special permanent magnet magnetic separator, YCMC series permanent magnet pulsating magnetic separator, magnetic separation column, etc.; b. Permanent magnetic bulk ore dry magnetic separator, representative of CTDG series permanent magnet bulk Dry-type magnetic separator for ore; c. Medium magnetic field permanent magnetic cylinder magnetic separator, representative of ZC, WCT series medium magnetic permanent magnetic cylinder magnetic separator. d. Strong magnetic separators, mainly CS series induction roller type strong magnetic separators, Shp series flat ring strong magnetic separators, Slon series vertical ring pulsating high gradient strong magnetic separators, DPMS series open gradient permanent magnet strong magnetic separators Machine, YCG series coarse-grain permanent magnetic roller type strong magnetic separator, etc.

2.5 Magnetic-reselection equipment