Iron ore process optimization

Guangdong big top iron ore is located in Heyuan City in Guangdong Province Lianping, from Heyuan city about 70km, ore type high-temperature hydrothermal replacement contact with magnesium skarn deposits, are open-pit mining. Mineral ore for use mainly magnetite, and with the illusion of a very small amount of hematite, limonite, hematite, cassiterite, occasionally a very small amount of harmful sulfide minerals such as sphalerite pyrite, non-metallic minerals are clinohumite, diopside, garnet, magnesium, iron spinel. Big Top beneficiation plant after several renovation and expansion, has formed the ore processing nearly 400 million t, 1.8 million t of concentrate production scale. It is worth mentioning that in the late 1990s, due to the overall downturn of the mine, other companies built a new concentrating plant in the mining area of ​​Dading Iron Mine, processing iron concentrates (annual processing capacity of 500,000 tons), to At the end of 2002, the workshop had been discontinued for other reasons. At the beginning of 2006, the concentrator was re-acquired by Dading Iron Mine and became the second workshop of Dading Iron Mine. Due to the good nature of the previous ore, the production process from the crushing system to the concentrate dewatering system is very simple. In order to put the workshop into production as soon as possible, the mine after the acquisition will overhaul the production equipment of the workshop. However, after a period of production, due to the change of ore properties, the process is difficult to adapt to the existing mining conditions, production efficiency is low, product quality Lower, it is difficult to meet the requirements of sales. It is imperative to transform the production process of the workshop.

First, the crushing process

The original crushing system process is three-stage open circuit breaking, and the flow chart is shown in Figure 1. The process has a grain size of -450mm and a final particle size of 35mm, which directly affects the production efficiency of the ball mill. The ore particles are listed.

Figure 1 The crushing process before the transformation

Table 1 Analysis of the grain size of the ore before the transformation (mm)

It can be seen from Table 1 that the final product of this process has a maximum particle size of 35 mm, a large coarse fraction, and an unstable content of fine fraction, and the ratio of fine particles to -12 mm is less than 20%, which has an effect on the efficiency of grinding. Larger. Mainly because the process is open and broken. At the same time, the sampling and analysis of waste waste rock, the grade of waste rock reached 8% to 13%, the grade fluctuations are large, mainly because the size of the broken product is large, and some of the continuous body enters the waste rock, otherwise the waste rock is difficult to throw.

Second, the transformation plan

The general idea of ​​the transformation is to change the original open road crushing into closed circuit crushing. The specific measures are as follows: 1 Remove the original vibrating screen and throwing waste device, and build a first level crushing bin (about 30m ³ ) in the space. The belt feeding with frequency conversion speed control enters the fine cone, which can be adjusted according to the material filling condition of the crushing chamber; 2 Considering the production capacity of the existing 2 fine crushed PYD1200 cones is difficult to meet the needs of closed-circuit production, and the crushing effect is poor. One of the PYD1200 is changed to the HP300 cone. Considering the high efficiency of the HP cone, the HP300 cone is normally operated, and the PYD1200 cone is operated under special conditions. 3 The cone discharge belt is extended and the belt slope is increased to 8%. Install a 2YAH1536 vibrating screen on the head of the belt, and add 3 belt conveyors. The material on the screen will enter the upper buffer mine with these 3 conveyors. 4 The 2mm part of the vibrating screen will be transported through the sand pump. Wet magnetic separation, after the waste is thrown into the classifier, the sand returning part directly into the ball mill, the overflow becomes magnetic powder after magnetic separation; 5 the middle grain size of the vibrating screen is -12+2mm part The process flow after the transformation is shown in Figure 2. The grain size of the ore is shown in Table 2.

Figure 2 The crushing process after the transformation

Table 2 Table of grades of milled ore after transformation (mm)

It can be seen from Table 2 that the process after the transformation completely realizes closed-circuit crushing, and the final product has 95% of the -12mm fraction, and the -12mm fraction can reach 20%, and the crushing granularity is obviously improved. In addition, after the transformation, the full-grain throwing is realized. According to the sampling analysis of the waste rock, the grade of waste rock is 6% to 9%, the grade of grinding can be increased by 5%, and the grinding efficiency is obviously improved.

Third, the grinding process

(1) Original grinding process

The original grinding process of the workshop is two single semi-opening and semi-closed one-stage grinding two-stage magnetic separation grinding production process (Fig. 3), in which the classification equipment for forming closed circuit with grinding is a linear vibrating screen. The size is 0.4mm, and the material on the linear screen can enter the 1 ^# or 2 ^# ball mill through the forward and reverse of the belt. Due to the nature of the ore in the early stage, the grinding fineness reaches -200 mesh, the content of 30% concentrate can reach more than 62.0%, and the dewatering of concentrate is combined with natural stacking and excavator extrusion, and the sales cost is very high. Big. As the nature of the ore changes, the concentrate grade drops to 59%, making it difficult to meet the needs of the sales market. In order to ensure product quality, it is imperative to improve the fineness of grinding. Since the screening efficiency of the linear sieve itself is low, if the mesh size is further reduced, the screening ability and efficiency are directly affected, and the circulation amount is too large, and the processing amount of the mill is difficult to be improved. Therefore, only relying on a linear screen to control the fineness of grinding, the fineness of grinding is difficult to improve, the original grinding production process is difficult to meet the product quality requirements, and due to the high moisture content of the concentrate, the loss of concentrate transportation is serious, Under the principle of minimizing downtime and saving investment, it is planned to carry out technical transformation of the grinding process.

Figure 3 Grinding process before the transformation

(2) Reform plan

The general idea of ​​the transformation is to change the grinding process to the second stage grinding stage, and use the existing idle equipment as much as possible to save the transformation time and reduce the impact on production. The modified grinding production is shown in Figure 4. The specific measures are:

1. Considering that the existing two linear screens have a long service life, the girders are broken many times, and because the eccentric shaft structure is adopted, the failure rate is high and the maintenance workload is large, so the USL model straight line adopting the eccentric block structure is decided. The screen was replaced by the ZKX type, and the mesh size was adjusted to 0.3 mm.

2. Considering that the space on the site and the height difference are small, add a platform above the 2# ball mill , install 2 Φ500 cyclones (idle equipment, one work and one spare), sanding and linear sieve on the screen material (+ The 0.3mm part) enters the second section of the grinding (2 ^# ball mill), and the original 2 ^# mill's feeding belt is removed.

3. Establish a sand pumping station on the side of the magnetic separator, adding 2 sets of 8/6E-AH sand pumps (one work and one standby), equipped with variable frequency speed control to control the pump pool liquid level and sand pump speed to achieve the voltage stabilization effect. . The lower part of the linear sieve (-0.3mm) is thrown into the sand pump after being discarded by the magnetic separator, and is sent to the cyclone by the sand pump for control classification.

4. Add a Φ1050×2100mm magnetic separator as a selection, and the cyclone overflowing directly into the magnetic separation operation.

5. Install a 60m ² vacuum disc filter under the selective magnetic separator. After the magnetic separation concentrate enters the filter for dewatering, the part of the ore is transported to the concentrate shed by the moving belt.

6. Add a Φ1000mm disc type magnetic separator in the middle of the tailings pipe to collect all the tailings slurry in the workshop for recycling, and the recovered medium ore will be returned to the production process.

After the transformation, the content of 1 grinding fineness -200 mesh can be increased from the original 30% to 40% to 55% to 65%, the product quality is stable above 62%, meeting the sales requirements; 2 the concentrate water is obviously improved. The water content drops below 8%, which greatly reduces the sales cost and the loss of product mines. The grade of 33 tailings has dropped from 9% in the past to about 6% at present, and about 800 tons of medium ore with about 40% of iron can be recovered every month. , reducing the loss of resources; 3 Although the fineness of grinding is greatly increased, the production capacity after transformation still reaches the production level before the transformation.

Figure 4 modified grinding process

Fourth, the conclusion

Through the optimization and optimization of the overall process of the second dressing workshop, the economic indicators of the beneficiation have been significantly improved, and the expected targets have been achieved. The economic benefits of the enterprises have increased significantly, mainly including:

1. Give full play to the crushing effect of the HP series of cones, and the grain size of the grinding is obviously improved. For this reason, the coarse ball of a grinding dress is further adjusted. The ball is changed from the original maximum diameter φ130mm to the current φ100mm, steel. The ball consumption has dropped by 50g/t, and the service life of the mill liner has been significantly improved.

2. The grade of the grinding mill is obviously improved, and the waste rock is reduced.

3, grinding fineness control can meet the requirements, product quality is guaranteed, and meet the sales requirements.

4. The grinding efficiency is obviously improved. Although the fineness of grinding is greatly increased, the production capacity has not decreased, and the output before the transformation is reached.

5. The product moisture is controlled, which reduces the mine consumption of the product.

6. The waste after the fine crushing and the final tailings grade are controlled, reducing the loss of resources.

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