Rational use of dry selection coal preparation technology to enhance coal quality

With the increasingly fierce competition in the coal market, the quality of raw coal in the Donghai mine has been seriously affected, which has increased the difficulty of coal sales in the mine. In response to this phenomenon, Donghai Mine has adopted limited mining of high-ash coal seams, controlled the mining of semi-coal rock into coal warehouses, tried to achieve coal-rock sub-assembly and transportation, and strengthened the management of coal mining face roof, but it did not fundamentally The role of ash reduction and quality improvement has not only changed the sales situation, but also caused the increase of the cost per ton of coal and the decline of production, which seriously affected the economic benefits of the whole mine.

There is no coal preparation plant in Donghai Mine. The method used to drain and reduce ash from raw coal and improve coal quality is a problem that plagues the mine. The vast number of engineering and technical personnel of Donghai Mine have made sufficient investigation and investigation, and demonstrated the comparison. Coal to solve this problem. Its investment use does bring considerable economic benefits.

l Coal quality analysis

1.l coal quality status

The current mining coal seam of Donghai Mine is No. 32 and No. 35, the coal ash content of the recoverable coal seam is 36% to 38%, and the raw coal ash is 4l% to 43%. Due to the imbalance of mining proportions, the five-and-a-half coal briquette team used continuous transportation and directly entered the coal bunker. Therefore, the plutonium rate reached 11%. The mined coal is only picked up by hand to improve the coal quality, so that the -50 mm vermiculite is mixed into the commercial coal, so that the commercial coal ash content is about 38%, which greatly exceeds the user's requirements and seriously affects the sales of coal. The coal quality of Donghai Mine is shown in Table 1.

1.2 Raw coal screening test results

The test results of raw coal screening are shown in Table 2.

1.3 Analysis of coal quality data

From the analysis results of coal, it can be seen that the properties of coal in the East China Sea are as follows:

(1) l/3 coking coal with high ash, low sulfur and low calorific value, which can be used as power coal or man-made coal blending;

(2) The quality of raw coal is poor, and the rate of niobium is high. Only when coal processing is carried out can the quality of the product be lowered and the requirements of users can be met;

(3) The coal ash with a particle size of more than 25mm is high, the calorific value is low, and the mass of less than 25mm is relatively good, indicating that most of the vermiculite is concentrated in the coal of more than 25 mm.

(4) Most of the vermiculite in the raw coal is carbonaceous shale , the ash content is about 70%, it is not easy to be crushed, and it is not easy to muddy when it meets water;

(5) According to the optional curve drawn by the floating-sink test data, it can be found that the sorting density is nearly 2.0, which is difficult to select coal.

2 Selection of dry coal preparation plan

2.1 program selection

According to the characteristics of the coal quality of the mine, there are two kinds of schemes that can be considered: the selection of the moving sieve jig and the drainage; the selection of the composite dry sorting machine. After market research and careful analysis, it is believed that the water-saving moving sieve jig that has appeared in recent years has relatively high water consumption and relatively high sorting precision. If a moving sieve system is used, a new washing system, slime dehydration and Precipitation and other supporting facilities, combined with the large size, high vibration and high installation conditions of the moving sieve jig, the investment is much higher than the dry selection.

And compound dry coal preparation and the movable sieve jigger, selective crusher selected from water and other methods as compared with simple equipment, easy operation and adjustment, sorted suitable particle size range, assist matching system is not complicated, need not increase the number The characteristics of civil engineering, etc., thus have the advantages of less investment, quick installation, less land occupation, no water use, no coal slurry water pollution, energy saving, and low production cost. After careful comparison of various programs, the mine decided to use dry method for coal preparation.

2.2 Composite dry sorter structure, sorting principle and characteristics

2.2.1 Structure

The composite dry sorting machine adopts the self-generated medium (fine coal contained in the raw coal) and the air to form a gas-solid two-phase mixed medium sorting; the mechanical vibrating makes the sorting material do the spiral turning movement to form multiple sorting; Sorting is performed using the buoyancy effect of the particle interaction produced by the gradually increasing bed density. The composite dry sorting machine has a structure as shown in Fig. 1.

The composite dry sorter consists of a sorting bed, a vibrator, a plenum, a frame and a hanging device.

2.2.2 Sorting principle

The sorting principle of the composite dry sorter is that under the condition of making the material spirally reversed, the combination of vibration force and wind force causes the bed to be loose and the ore particles to be stratified by density. Mixed media separation (clean coal section) formed by autogenous medium (powder coal) and air in different sections, and utilizing the buoyancy effect of particle interaction (middle coal section 1. Forming a different from any coal preparation The comprehensive sorting mechanism of the equipment is shown in Figure 2.

2.2.3 Features

(1) Less investment, no water, simple process, less equipment, small floor space, no need to build a factory;

(2) Low production costs and high labor productivity. The processing fee per ton of raw coal is only about 2 yuan, which is lower than all coal preparation methods. Due to the small amount of labor, the labor productivity can reach 50~80t/work;

(3) The recovery rate of commercial coal is high. Compared with washing, no coal slime is produced, not only can the fine-grained coal be effectively recovered, but also the coal dust collected by the dust-removing system can be completely recovered;

(4) The moisture of the commercial coal after the selection is low. Not only does it not increase the moisture of the raw coal, but it also has a certain dehydration effect. Reduce the influence of the moisture of the washing product on the calorific value of the commercial coal;

(5) It can produce a variety of products with different ash, which is beneficial to the operators to obtain the maximum economic benefits under the conditions of satisfying the users of commercial coal;

(6) The construction period is short and the production is fast. The composite dry selection system is a steel structure and assembled coal preparation plant. It is assembled according to the installation location map provided by the equipment manufacturer. Generally, it can be installed, commissioned and put into production within half a month;

(7) Smooth operation, small maintenance and simple operation. The composite dry sorter has no transmission components. The vibration motor has no fault operation and is guaranteed to be 1.0×104 h.

After the Donghai Mine improved the coal quality program and carried out the feasibility analysis of the dry coal preparation technology, according to the output of the mine, two FGX-9 dry sorters were put into operation in 2001, and the treatment capacity reached 120 t/h, which satisfied the production. need.

2.3 Operation and sorting results

2.3.1 Sorting effect

Since the dry selection system of Donghai Mine has been put into operation since January 2001, the operation of various equipments has been in good condition. During the whole production process, the mine paid attention to the production technology inspection and quality measurement work, and timely feedback various information to guide the operation. Seek the best sorting results and economic benefits.

Statistical analysis of the effect of sorting in 2005 is shown in Table 3.

After dry coal preparation, the raw coal of Donghai Coal Mine is sorted by sorting machine. After the selection, the coal ash content is reduced by 8%-10% compared with the original coal, the calorific value is increased by 2512-3349kJ/kg, and the commercial coal yield is above 75%. .

2.3.2 Benefit Analysis

The annual processing capacity of the East China Sea mine is 1.2 million tons. The sieve material above 25mm accounts for 30% of the raw coal. Therefore, the raw coal of the dry sorter is 360,000 t/a, and the coal price is increased by 5 yuan for each 1% increase in ash. t, then the price per ton of coal after the dry selection is increased by 50 yuan. The processing fee for the dry selection system is 3 yuan/t, and the annual profit increase of each mine is shown in Table 4.

3 Conclusion

After years of actual operation of the East China Sea Coal Mine, Donghai Coal Mine has a full understanding of the composite dry coal preparation technology. This coal preparation technology is both economical and affordable. The coal preparation technology is deeply loved by the coal mining enterprises for its unique characteristics. The successful case of the coal preparation technology has a good guiding role for coal preparation plants and coal preparation enterprises.

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