What are the methods to improve the grade of iron concentrate?

Many domestic iron ore concentrators are on the verge of small profits and losses due to backward beneficiation technology, outdated and crude equipment, and small scale of manufacturers. Since 2003, my country’s steel supply has gradually increased, and the demand for iron concentrate powder has also continued to rise. Due to the increase in demand, many mineral processing plants of different levels have emerged in my country. In early 2005, subject to the constraints of the country’s steel macro-control, the price of iron ore concentrate dropped sharply. Many iron ore concentrators have no mines of their own, backward beneficiation technology, old and crude equipment, small scale manufacturers, low grade concentrates, low supply quotations, and supply difficulties. This type of concentrator is on the verge of small profits and losses. How to make this type of manufacturers develop, be profitable and competitive is an important issue facing the leaders of this type of mineral processing plant.
After many years of research on designing mineral processing equipment and manufacturing mineral processing products, the state-owned Zhengzhou Mining Machinery Factory has summarized a complete plan for the mineral processing plant to improve product quality, reduce production costs, and improve economic benefits. After the existing backward mineral processing plants have undergone technological and equipment transformation, their product quality and production costs can reach the level of domestic advanced mineral processing plants. After analysis, the backward mineral processing plant has the following problems that should be solved: 5mm is reduced to 10mm, and the power consumption of the fine crusher for crushing 1 ton of ore is 5KWl. Instead, use fine crushing equipment to finely crush the ore before grinding. In this way, the power consumption of 1 ton of ore in both crushing and grinding systems can be reduced by 7KWF. Moreover, the cost of the hammer head lining plate consumed by the fine crushing equipment before grinding is significantly lower than the cost of the steel balls and lining plate of the ball mill. An ore dressing plant that processes 100,000 tons of ore annually can save 400,000 yuan in electricity and material costs by adopting advanced technology in the crushing and grinding process.
Problems in raw material crushing and grinding systems
The particle size of the ore crushed before grinding in a small-scale mineral processing plant is about 25mm, which greatly reduces the grinding power of the mill. Since the mill is a fine grinding equipment and the coarse crushing power of the mill is low, the grinding power when grinding 25 mm (mm) ore to below 80 microns (um) is very low. At this time, 1 ton of medium-hard ore requires about 25KWH of electricity. The advanced crushing process has now broken the ore to a particle size of less than 10mm. At this time, the power consumption of the mill to grind 1 ton of ore is only about 13KWH. The method is to add a fine crusher to the raw material coarse crushing system to reduce the particle size of the ore in front of the mill from 25mm to 10mm. The fine crusher consumes 5KWH of electricity to crush 1 ton of ore. Instead, use fine crushing equipment to finely crush the ore before grinding. In this way, the power consumption of 1 ton of ore in both crushing and grinding systems can be reduced by 7KWH. Moreover, the cost of the hammer head lining plate consumed by the fine crushing equipment before grinding is significantly lower than the cost of the steel balls and lining plate of the ball mill. An ore dressing plant that processes 100,000 tons of ore annually can save 400,000 yuan in electricity and material costs by adopting advanced technology in the crushing and grinding process.
Choose energy-saving, high-yield crushing equipment
There are many fine crushing equipment for ores, and there are few ideal equipment for users to choose from. According to major users, the shortcomings are that the hammer head and lining plate in the crusher are consumed and replaced frequently, and the unit-time output value is low and the power consumption is high. , maintenance and repair are difficult and time-consuming, and the equipment operating rate is low. For example, in hammer crushers, whether it is a vertical shaft hammer crusher or a horizontal hammer crusher, the hammer head has a short service life. The shortest one has to be replaced every three to five days, and the longest one only needs to be replaced every half a month. once. The cost of hammer head and lining plate is as much as 1 yuan for 1 ton of ore, and the power consumption for crushing 1 ton of ore is 7KWH. Here they recommend to users an energy-saving bearing cone crusher with low consumption of wearing parts, long service time, high output value, stable discharge particle size, and low power consumption. The power consumption can be reduced from 7KWH/ton of ore in other fine crushers to 5KWH/ton of ore. tons of ore. The service life of lining plate consumption materials can be increased from one week to half a year. The lining plate and hammer head wear-resistant steel consumed for crushing 1 ton of ore is about 0.2 kg/ton of ore, which has dropped to 0.01 kg/ton of ore, which has dropped by nearly 20 Times as much. To learn more about this equipment, please refer to the operating instructions of the “Energy-Saving Bearing Cone Crusher”.
Choose energy-saving, high-yield grinding equipment
1. The main bearings of ordinary grinding ball mills currently used in the market are Babbitt bearings, which have high working resistance and high oil consumption. The bearings of large mills need to be equipped with lubrication stations, which are difficult to repair and maintain. Grinding 1 ton The power consumption of ore is about 25 kilowatt hours (KWH); the rolling bearings used in the main bearings of energy-saving ball mills now consume about 18KWH for grinding 1 ton of ore. Use dry oil lubrication to save more than 80% of lubricating oil annually. The large mill eliminates the lubrication station of the main bearing, requires maintenance only once a year, and the equipment operating rate can reach 100%.
2. The linings of ordinary ball mills are bar-shaped, ladder-shaped, and corrugated. The disadvantage of these linings is that when the linings are worn to a certain thickness, they will bend and deform, resulting in inoperability; another flaw The surface shape of the lining plate is simple, the contact area between the steel ball and the lining plate is small, the grinding capacity is insufficient, and the grinding efficiency is low, resulting in low output value of the mill. It is recommended that users choose double U-shaped lining plates. The advantages of this lining plate are that it has corrugations along the circumferential direction of the mill barrel and grooves along the axis of the mill. When the mill is working, the grinding body is raised to a large height, and the contact surface with the lining plate increases the grinding efficiency. This kind of lining plate increases the output value by more than 6% compared with ordinary grinding machines.
Improve the classification performance of the concentrate after grinding, reduce the phenomenon of over-grinding, and improve the grade of the concentrate powder
In some mineral processing plants, the finely ground ore powder directly enters the magnetic separator for magnetic separation. For example, in a mineral processing plant in Jiaocheng, Shanxi, the ball-milled mineral powder is directly magnetically separated without classification. As a result, the particle size of the mineral powder metallurgy is uneven. Coarse-grained ore powder is of low grade; although finer ore powder is of high grade, its magnetic field strength is low and its adsorption capacity is poor. As the water flows into the tailings, the grade of the iron concentrate powder is low, and the tailing phenomenon is serious. Suppliers of this mineral processing technology are reminded that the ground materials must be graded and sorted, and then magnetically separated. Because different ores have different monomer dissociation particle sizes at the highest grade. If the particle size is too coarse, the impurities in the ore cannot be separated, and the grade of the ore will be too low; if the particle size is ground too fine, the grinding capacity and grinding time of the mill will be wasted. Because the ore particle size below 10 μm is added to the ore powder by 1%, the grinding time will be increased by 2%, and the power consumption and the wear of the steel ball liner will be increased by 2% accordingly; therefore, every effort is made to reduce the over-grinding mineral deposits. It is the most effective way to increase the output value of the mill, reduce power consumption and increase the recovery rate of iron concentrate powder. After adopting the group screening method, the mineral deposits whose particle size does not meet the requirements are returned to the mill for regrinding, and the mineral deposits whose particle size reaches the required particle size are sent to sorting in time, which not only improves the grade of the concentrate, but also improves the grinding efficiency of the mill. .
There are many ways to classify mineral deposits, among which the spiral classifier is the most primitive grading equipment. The grouping method is simple and the classification accuracy is slightly poor. It is generally used in the classification of one-stage grinding and discharge products. When it is required that the final product particle size of iron ore concentrate is minus 80 μm and the sieve reduction reaches 100%, a spiral classifier can be used for the first stage of classification; a high-frequency fine screen can be used for the second stage of classification. If the final product particle size of iron concentrate powder metallurgy dies is required to be minus 80 μm and the content is less than 100%, the proportion of large particles is relatively small, and the wear of the high-frequency screen is not serious, a high-frequency vibrating screen can be used Classification is carried out, and the medium ore under the screen is magnetically separated; the coarse ore above the screen is returned to the mill for regrinding. Another type of classification equipment is the hydrocyclone. Nowadays, there are many large-scale mineral processing plants that have removed the spiral classifier equipment after the first- and second-stage mills and replaced them with hydrocyclones. This method can not only coarsely classify ore powder, but also increase the concentration of slurry before magnetic separation and reduce the need for first-level dehydration equipment. This equipment is also used to classify and concentrate the slurry before re-selection of non-magnetic ore powder, playing an outstanding role. How to choose classification and selection equipment, please refer to the relevant mineral processing equipment manual and the company’s classifier, high-frequency screen, and hydrocyclone operating instructions.
To sum up, the low-level mineral processing plant has improved its product quality by more than 66.5% through technological transformation, allowing it to obtain an excellent supply quotation. Through the transformation of equipment technology, its production power consumption has been reduced by more than 25%, and the output value has been increased by about 30%. The consumption of steel materials such as lining plates, hammer heads, and steel balls has been reduced by more than 15%, bringing the comprehensive economic indicators to the domestic advanced level, improving the manufacturer’s economic benefits, increasing the manufacturer’s competitiveness, and laying the foundation for the manufacturer’s future continuous development and strength. Excellent conditions were created.