Since 2003, the iron and steel sales of China, a mineral processing equipment in Henan Province, have gradually increased, and the demand for iron concentrate powder has also been rising. Due to the increase of demand, there are more concentrator with different grades and levels in China. At the beginning of 2005, influenced by the national macro-control of iron and steel, the price of iron concentrate powder fell sharply.
Problems existing in raw material crushing and grinding system
The particle size of crushed ore before grinding in a small concentrator is about 25mm, which greatly reduces the grinding efficiency of the mill. Because the mill is a fine grinding equipment, the grinding efficiency of 25mm (mm) ore is very low when it is ground below 80μ m (micron), because the grinding efficiency of the mill is low. At this time, the power consumption of 1 ton medium hardness ore is about 25KWH. Advanced crushing technology has crushed the ore to the particle size below 10mm, and the power consumption of grinding 1 ton ore is only about 13KWH. The method is to add a fine crusher to the raw material coarse crushing system, so that the ore particle size before grinding is reduced from 25mm to 10mm, and fine crusher crushing 1 ton ore requires 5KWH. Before grinding, the ore is finely crushed by fine crushing equipment, which reduces the power consumption of crushing system 1 ton ore by 7KWH. In addition, the consumption cost of hammer liner consumed by fine crushing equipment before grinding is obviously lower than that of ball mill and liner. A concentrator with an annual processing capacity of 654.38+10,000 tons can save 400,000 yuan in electricity and material consumption by adopting advanced technology in the grinding process.
Henan mineral processing equipment adopts energy-saving and high-yield crushing equipment. There are many fine ore crushing equipment, but there are few ideal equipment for users to choose from. According to the shortcomings reflected by the main users, the hammer head and liner in the crusher are frequently consumed and replaced, with low output and high power consumption, difficult maintenance, long time and low equipment operation rate. For example, hammer crushers, whether vertical shaft hammer crushers or horizontal hammer crushers, have a short service life, with the shortest replacement once every three to five days and the longest replacement once every half a month. The consumption of hammer head and liner 1 ton of ore is as high as 1 yuan, and the crushing 1 ton of ore is 7 kwh. Here, they recommend an energy-saving bearing cone crusher with low wearing parts consumption, long service life, high output, stable discharging granularity and low power consumption to users. The power consumption can be reduced from 7 kWh/ton of ore in other fine crusher to 5 kWh/ton of ore. The service life of lining materials can be increased from one week to half a year, and the consumption of wear-resistant steel such as lining plates and hammers for crushing 1 ton ore is about 0.2 kg/ton, which is reduced to 0.0 1 kg/ton ore, which is nearly 20 times higher. For detailed information about this equipment, please refer to the instruction manual of energy-saving bearing cone crusher.
Henan mineral processing equipment selects energy-saving and high-yield grinding equipment.
1. At present, the main bearings of ordinary grinding ball mills used in the market are babbitt tile bearings, which have large running resistance and high oil consumption. The bearing of large mill needs to be equipped with lubrication station, which is difficult to maintain. The power consumption of grinding 1 ton ore is about 25 KWH. At present, the main bearing of energy-saving ball mill adopts rolling bearing, and the power consumption of grinding 1 ton ore is about 18KWH. Dry oil lubrication can save more than 80% lubricating oil every year. The main bearing lubrication station is removed from the large mill and only needs to be maintained once a year, and the equipment operation rate can reach 100%.
2. Liners of ordinary ball mills are strip, stepped and wavy. The disadvantage of these linings is that they will bend and deform when worn to a certain thickness, so they cannot be used. Another disadvantage is that the surface shape of the lining plate is simple, the contact area between the steel ball and the lining plate is small, the grinding ability is not enough, and the grinding efficiency is low, resulting in low mill output. Here, users are recommended to adopt double U-shaped liner, which has the advantage of corrugation along the circumference of the mill barrel; There are grooves along the axis of the milling cutter. When the mill is running, the height of the grinding body increases, and the contact surface between the grinding body and the lining plate is more, which improves the grinding efficiency. Compared with the common mill, this liner can increase the output by more than 6%.
Improve the classification performance of concentrate after grinding, reduce over grinding and improve the grade of concentrate powder.
The ground mineral powder of a concentrator directly enters a magnetic separator for magnetic separation. For example, in a concentrator in Jiaocheng, Shanxi Province, the ore powder after ball milling is directly magnetically separated without classification, resulting in uneven particle size. Coarse ore powder has low grade; Although superfine mineral powder has high grade, its magnetic field strength is low and its adsorption capacity is poor. With the water flowing into the tailings, the grade of iron concentrate powder is low and the tailings phenomenon is serious. It is suggested that the manufacturers of this beneficiation technology must classify and screen the ground mineral materials before magnetic separation. Because different ores have different particle sizes of monomer dissociation 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 is too low; If the particle size is too fine, it will mainly waste the grinding capacity and grinding time of the mill. Because the particle size of ore below 10μm, the grinding time will increase by 2% with each increase of 1% of the ore powder, and the power consumption and the wear of the steel ball liner will also increase by 2% accordingly. Therefore, doing everything possible to reduce the content of over-ground minerals is the most effective way to increase mill output, reduce power consumption and improve the recovery rate of iron concentrate. After adopting grouping screening measures, the minerals with unqualified particle size are returned to the mill for regrinding, and the minerals with qualified particle size are sent to separation in time, which not only improves the concentrate grade, but also improves the grinding efficiency of the mill.
There are many methods of mineral classification, among which the spiral classifier is the most primitive classification equipment. The grouping method is simple and the classification accuracy is slightly poor, so it is generally applied to the classification of minerals discharged from primary grinding. When the particle size of the final product of iron concentrate reaches 65438±80 μm%, the spiral classifier can be used for the first grade classification. High frequency fine screen can be used for secondary classification. If the particle size of the final product of iron concentrate powder is required to be less than 65438+80μm%, and the proportion of large particles is small, the high-frequency vibrating screen can be used for classification, and the middling under the screen can be magnetically separated on the premise of not seriously wearing the high-frequency screen; The coarse ore on the sieve is sent back to the mill for regrinding. Another classification device is a hydrocyclone. At present, many large-scale concentrator have used hydrocyclones to replace the spiral classification equipment after the primary and secondary mills. This method can not only classify the thickness of mineral powder, but also improve the pulp concentration before magnetic separation and reduce the number of primary dewatering equipment. The equipment is also used for pulp classification and concentration before gravity separation of non-magnetic mineral powder, and good results have been achieved. For the classifier, high-frequency screen and hydrocyclone, please refer to the relevant mineral processing equipment manual and the company's operating instructions.
To sum up, the low-grade concentrator has improved the product grade by more than 66.5% through technical transformation, thus obtaining a better sales price. Through the technical transformation of equipment, the production power consumption decreased by more than 25% and the output increased by about 30%. The consumption of steel products such as liners, hammers and steel balls is reduced by more than 15%, which makes the comprehensive economic indicators reach the domestic advanced level, improves the economic benefits of enterprises, increases the competitiveness of enterprises, and creates good conditions for the continuous development and growth of enterprises in the future.
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