Measures for the concentrator to improve the quality of iron concentrate and reduce production costs

Selected Works of Professor Chen Wen from Changsha Research Institute of Mining and Metallurgy:

Since the introduction of the thought of the iron and silicon-reducing silicon (mixed) of the academician Yu Yongfu, the domestic concentrating plant has gradually changed from pursuing the quality and recovery rate of the iron concentrate to the pursuit of improving the quality of iron concentrate, energy saving and emission reduction, and increasing economic benefits. New technologies, new processes, new equipment and new pharmacy suitable for various types of iron ore to improve quality, reduce cost and increase efficiency have been developed, and remarkable results have been achieved.

A process using pre

Pre-selection refers to the pre-separation of some tailings by a suitable beneficiation method before the ore enters the grinding operation. Due to the rapid development of metallurgical industry, more and more demand for iron ore, coupled with the development of the mining industry, the use of advanced mining methods and large-scale mining equipment, ore grade mined decreased, increasing the dilution rate. In order to improve the grade of grinding ore, save energy consumption in the plant, and reduce the amount of grinding, in recent years, magnetic pre-selection processes have been widely used in magnetic separation plants at home and abroad.

Bengang Shantou Iron Ore Concentrator, before the crushing into the self-grinding, the 350-0mm ore is preselected with CTDG1516 large ore permanent magnetic dry magnetic separator, throwing waste yield 12-13%, so that The grade of grinding ore increased by 3.62 percentage points, the recovery rate of magnetic iron was over 99%, and the annual economic benefit reached more than 10 million yuan. The first selection of the Changling Gongchangling Concentrator, using the CTDG-1220N large ore permanent magnetic dry magnetic separator to pre-select the 75-0mm medium crushed product, the ore grade is 31.61%, the concentrate grade is 33.68%, and the tailings yield is 8.73. %, grade 9.97%, iron recovery rate of 97.04%, annual economic benefit of 43.5 million yuan. Shougang Water Plant Concentrator adopts C80 type permanent magnet magnetic pulley for 12-0mm fine crushed products, dry pre-selection of one coarse and one sweeping process, can discard the yield of 8-9%, grade 10.50% qualified tailings, improve the grade of grinding ore 1-1.5 percentage points. The amount of tailings discarded is basically equal to increasing the grinding amount of a system, which creates favorable conditions for the high-quality concentrate to improve the quality of the concentrate.

Kunming Steel Wangjiatan Lingtie Mine uses the generalized magnetic separator developed by Changsha Research Institute of Mining and Metallurgy to carry out coarse pre-selection of 0-6mm ore. The grade of siderite can be increased from 31.45% to 35.18%, and the pre-selection effect is remarkable. The total reserves of Jiuganggou iron ore in Jiugang are 270 million tons. The main iron minerals are mirror iron ore, siderite and limonite, all of which are weak magnetic iron ore; the gangue minerals are jasper, barite and quartz . In order to improve the iron grade of ore processing in the ore dressing plant, in August 2002, the Huashugou iron ore mine completed a pre-selected tailing project with an annual capacity of 4.5 million tons. The tailing equipment used the permanent magnet of Outokumpu Company of the United States. The magnetic separator, pre-selection of 15-30mm grain grade lump ore, can throw out the qualified tailings with a yield of 13.66% and a grade of 10.43%. The iron grade of the ore is increased from 34.12% to 37.86%; for the 0-15mm grain size The pre-selection of the fine ore was carried out, and the tailings yield of the thrown was 11.04%, the grade was 12.13%, and the iron grade of the ore was increased from 31.90% to 34.35%. The iron ore mine's cut-off ore grade has been reduced, transportation costs and ore processing costs have been reduced. After the project was put into production, the direct economic benefit was more than 5 million yuan in 2005.

Another advantage of the pre-selection process is that it can throw qualified tailings of coarser size, and directly filling it into the goaf can not only solve the tailings discharge problem, but also reduce the filling cost, and has good environmental benefits and economy. benefit.

2 using multiple crushing and grinding process

The energy consumption of crushing and grinding operations accounts for 50-70% of the total energy consumption of the concentrating plant. The energy consumption of grinding operations accounts for more than 80% of the energy consumption of grinding operations. The effective way to reduce the energy consumption of grinding operations is to reduce the energy consumption. Grinding ore particle size, that is, more crushing and less grinding. The main measure is to adopt a new type of crushing equipment with large size, large crushing ratio, high efficiency and low consumption, which reduces the particle size of the ore. In recent years, China's factory has introduced the high-efficiency hydraulic cone crusher from foreign companies such as Sandvik and Metso to reduce the grain size of the ore into 12(10)-0mm, and the energy saving effect is obvious. For example, the crushing system after the expansion of Taishan Jianshan Iron Mine has replaced 6 domestic 2200-type cone crushers (2 pieces in medium and 4 pieces in fine crushing) into imported Metso HP-500 type crushed with large production capacity and good crushing effect. The machine and Sandvik H-8800 crusher make the crushed product particle size -12mm content reach 90%, the overall capacity of the concentrator is increased by more than 8%, and the hourly power consumption is 128KW.

The use of a high-pressure roller mill is also an effective measure to reduce the size of the ore. Due to the working principle of laminating crushing, the high-pressure roller mill has high energy utilization rate, and the energy consumption of ore crushing is generally 0.8-3.0 KW•h/t, which is about 30% more energy-saving than conventional crushing equipment, and the system output is increased by 25-30%. . It has been promoted and applied in domestic iron ore dressing plants. The Mashan Iron and Steel Nanshan Iron Mine Concavation Concentrator has broken the 18-0mm fine crushed product to 3-0mm by introducing a German Koeppern RP630/17-1400 high-pressure roll mill to make the processing capacity of the concentrator 5,500,000 t / a is increased to 7,000,000 t / a.

3 Apply new technologies and equipment

The main influence of the magnetic separation concentrate grade is the continuous body of magnetic iron mineral and quartz gangue. It is impossible to separate the continuum by multiple magnetic separation. Only the cation or anion reverse flotation technology is used to utilize the continuum. After the action of quartz and flotation reagents, the surface of the quartz can be adhered to the bubbles to be easily floated, and the separation of the continuum and the iron minerals can be achieved to achieve the purpose of desiliconization and improving the quality of the iron concentrate. The sorting technology has a good effect. From 2002 to 2008, the production technical indicators of the ore dressing plant rebuilt and expanded by the anti-flotation technology in China's iron ore dressing plant are shown in Table 1.

Table 1 female (male) ion collector reverse flotation desilication process is mainly concentrator production index

Further improving the demand for quality of domestic iron concentrates has also led to the research and development of high-efficiency new mineral processing equipment. Since 2000, a number of selected equipment for selecting magnetite ore have been developed in China, such as magnetic-gravity combined magnetic-heavy pulsation low magnetic field magnetic weight concentrator (magnetic separation column, panning magnetic separator), magnetic force and Particle size screening combined magnetic field screening machine, fine mesh MVS electromagnetic high frequency vibrating mesh screen and multi-magnetic BX weak magnetic separator, etc. These selected equipment can effectively disperse the magnetic agglomeration of materials, and discharge the poorly connected organisms and The gangue minerals improve the grade of iron concentrate, and some of the production indexes of magnetite ore plants are shown in Table 2.

For the sorting of weak magnetic red (brown) iron ore, in addition to the commonly used Slon-type vertical ring pulsating high-gradient magnetic separator, the near-Earth Sand Mining and Metallurgy Research Institute has developed a fine-grained weak magnetic red (brown). The new high-efficiency ZHI-type combined wet-type strong magnetic separator of iron ore has the advantages of high separation magnetic field strength, good recovery effect on fine-grained minerals and high recovery rate. The machine uses a coarse screen plus three compartments sorting disc structure, supporting the front compartment specialized filters to remove crude means of mechanical pulp inclusions and a minor amount of coarse particles of slag, the main sorting using a gradient of up to 104 Gauss dielectric multilayer induced magnetic poles The medium parameters corresponding to the three plates form a weak magnetic separation system of 0.1-0.3T on the upper plate to recover a small amount of ferromagnetic magnetite and pseudo-hematite. The middle plate is a medium magnetic separation system with 1-1.5T magnetic field strength. It is used to recover medium-grained hematite. The magnetic field strength of the lower plate is as high as 1.7-1.8T. It is extremely effective for recovering fine-grained hematite and limonite, and the second section of the Anhui Lilou Iron Mine The results of the selected split flow test show that, under the same conditions of the ore supply, compared with the Slon vertical ring magnetic separator, the iron concentrate grade obtained by the ZHI type strong magnetic equipment is 0.3 percentage points higher, and the tailing grade is 10.09 lower. Percentage points, the recovery rate of magnetic separation operations is 26.57 percentage points higher.

Table 2 new apparatus specifications iron ore sorting

2.4 R & D of new pharmaceutical processing

Due to the fine grain size of the poor hematite ore in China and the serious muddying during the fine grinding process, the anti-flotation technology of the anti-sludge mud is widely used in China. The anesthesia developed by the technology for the gangue minerals is mainly quartz. The combination of four chemical systems, such as NaOH, causticized starch, lime and fatty acid collectors, which are used efficiently by iron ore, has become a classic pharmaceutical system and has been used until now, although various research institutes and enterprises have introduced new types of anionic collectors. Hundreds of schools have contend, but for more than 20 years, there has been no fundamental technology beyond the principle process established at the beginning of the process development, four kinds of reverse flotation reagents, and flotation temperature above 30 °C.

In recent years, the main achievement in the research and development of anionic flotation reagents has been the development of an anionic flotation agent for the efficient use of refractory iron ore in Yuanjiacun Iron Mine, Anhui Lilou Iron Mine, etc. The main feature of this type of iron ore is the vein. In addition to quartz, stone minerals also contain a considerable proportion of iron-containing silicate minerals such as hornblende and chlorite. The newly developed medicinal agents not only have good selectivity for chlorite and hornblende, but also have The temperature adapts to a wide range and is resistant to mineral mud. The industrial applications of some newly developed pharmaceutical agents in recent years are listed in Table 3.

Table 3 Industrial application of new anionic agents

It can be seen from the table that for Anhui Lilou Iron Mine, the flotation index obtained by using the new agent is greatly improved under the condition that the new agent and the on-site original agent are in the same amount; for Taigang Jianshan Iron Mine and Division In the case of Jiaying Iron Mine, the direct effect of using new drug flotation is that the dosage of the drug is greatly reduced when the flotation index is similar. Compared with the original agent in the field, the flotation temperature of the three mines after the new agent was reduced, and the flotation temperature of the Sijiaying iron ore was the largest, up to 15 °C. It can be seen that the calculation of energy saving and emission reduction by reducing the flotation temperature of Sijiaying Iron Mine by 15 °C can save the investment of boiler and heating equipment and the operating cost of 24.24 million yuan/year, and the savings of other pharmaceutical costs is 6.0516 million yuan/year. cost reduction benefits are substantial; while the temperature is reduced very significantly improve the environmental benefits of 300 million t processing plant on an annual basis the amount of processing can be less 60 600 t raw coal per year, according to industrial boilers each burning one ton of standard coal, to produce Carbon dioxide 2.62t, sulfur dioxide 8.5kg, nitrogen oxide 7.4kg calculation, less than 158,800 tons of carbon dioxide, 515.1t of sulfur dioxide, 448.44t of nitrogen oxides per year; the temperature reduction can also effectively improve the working environment of employees and protect workers. Physical and mental health.

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