Application and improvement of moving sieve jigging

1 Introduction to moving sieve jigging

Moving Screen core to discharge refuse technology, is the use of moving jigger sorting blocks of coal and gangue separate pieces. When the moving sieve jig works, the water in the tank body maintains a certain liquid level, and the sieve bed located in the water is driven up and down around the pin shaft under the driving of the hydraulic cylinder rocker arm. After the material enters the moving sieve jig, it moves forward due to the movement of the rocker arm and the extrusion of the feed. When the sieve bed rises, the water medium moves downward relative to the material particles; when the sieve bed descends, the water medium forms an upward flow relative to the sieve bed, and the material particles interfere with sedimentation in the aqueous medium, and the particles are loosened and pressed on the sieve bed. Density stratification. After the layered light material passes over the overflow weir, it enters the rear end of the lifting wheel of the moving sieve jig, and the upper layer of the pouring chute is lifted by the lifting wheel to be discharged outside the machine; the heavy material is discharged through the drainage wheel, and the falling wheel is lifted. The front end is lifted and then the lower layer of the discharge chute is discharged to the outside of the machine; the permeable material is dehydrated by the bucket elevator and then enters the dewatering screen.

At present, the domestic advanced coal preparation production process mainly includes heavy medium selection and dynamic screening jigging. The moving sieve drainage process is applied to the washing and processing of large coal and vermiculite. The sorting efficiency and precision are equivalent to the heavy media separation. The two have the following advantages compared with the dynamic sieve drainage.

(1) The production process is simple, the equipment is small, and the running cost is low.

(2) Automatic washing of water, the amount of washing water is small.

(3) The operation is simple and the maintenance workload is small.

2 Application of moving sieve jigging

The optional coal of Xinglongzhuang Mine is extremely easy to select coal. There is very little coal in the coal (about 10%), the vermiculite is purer and the ash is higher (about 90%), and the original coal has a particle size of 50mm or more, accounting for 26.67%. Suitable for use with moving sieve jigs.

2.1 Process flow adopted by Xinglongzhuang Coal Mine Coal Preparation Plant

The raw coal from the mine is pre-classified by vibrating screen. The large coal and 50-300mm large coal and vermiculite are transported to the moving sieve workshop; the raw coal below 50mm enters the mixed coal storage and transportation system; the large piece of vermiculite and lump coal above 300mm enters the manual selection and loses The belt conveyor is shown in Figure 1. The original selective crusher is reserved, and the moving sieve workshop cannot be used for normal production, and is not used normally.

50-300mm large coal and vermiculite, after secondary screening, the sieved material enters the mixed coal storage and transportation system; the sieved objects are sorted by moving sieve jig, and the separated vermiculite is transported to the limestone warehouse; After the hoist is dehydrated, it enters the coal storage and transportation system; the selected lump coal is removed by the clean water oblique turbine, dehydrated and transported to the coal bunker or crushed and transported into the product warehouse.

2.2 Process indicators and effect analysis

According to the sorting performance data of the moving sieve jig and the contract with the manufacturer, the design capacity of the single cabinet of the ROM JIG20500808 type moving sieve jig is 238t/h, and the imperfection I value is less than 0.11. After the selection, the lime content is greater than 80%, and the impurity content in the product is less than 5X10-7.

The dynamic screening and jigging production system is based on the relevant standards issued by the State and the former Ministry of Coal, sampling, screening, floating and sinking tests, coal sample analysis, single machine test results: production capacity of more than 280t / h, imperfection I The value is 0.097. After sorting, the lime content is 81.45%, and the impurity content in the product is 1.79X10-7.

After the production of the moving screen jigging and drainage system was put into production, significant economic benefits were achieved. According to the financial statements of Xinglongzhuang Coal Mine in the first half of 2000, the production of the sifting and smashing production system was put into operation from January to June, increasing the sales profit of 16.808 million. Yuan, from this calculation, the investment payback period is 1.5a.

3 Improvement and innovation

3.1 Improve the process system

The production system originally designed and built can only produce 50-300mm lump coal and 2 kinds of products broken to 50mm or less. In order to meet the different needs of users, optimize the product structure, and install a grading screen before the product enters the warehouse to realize the hierarchical storage of lump coal. Screening is carried out before loading, so that the limit rate of the product is strictly controlled. Additional production and storage routes will be built to realize automatic coal blending.

3.2 Changing the way the permeable material is discharged

In the original design, the permeable sieve of the moving sieve jig, after the sedimentation in the lower sieve chamber, was alternately opened and closed by two Φ250mm hydraulic flapper valves, and discharged outside the machine. The disadvantages of this method are as follows:

(1) The two discharge valves are hydraulically driven, increasing the complexity of the hydraulic system and control system.

(2) The debris in the undersize chamber is easy to get stuck in the valve, and the accident rate is high.

(3) The amount of washing water is large.

(4) The discharged permeable material must be treated with a dewatering screen.

In response to the above problems, a bucket elevator is used to replace two hydraulic flapper valves. After the sieve is removed by the bucket elevator and dehydrated by itself, it is directly mixed into the sieved material of the secondary sieve and enters the coal storage and transportation system. .

3.3 Strengthening the impurity removal function

The overflow of the ROM JIG20500808 moving sieve jig is on the side of the tank. The guiding idea of ​​the design is that the overflowing water and floating debris (such as wood chips) on the surface of the water reach the moon along the A line, and the debris is blocked by the net scorpion. The washing water overflows and the tank body maintains a certain liquid level.

However, in practical applications, it is found that floating debris is difficult to reach the overflow mouth, but the C and D lines along the direction of the man-made material directly traverse the sides of the discharge chute. In view of this situation, two overflow ports were changed at the E and F2 points of the troughs on both sides of the discharge chute, which not only retained the guiding idea of ​​the original design, but also strengthened the decontamination of the moving sieve jig itself. Features.

3.4 Reform of hydraulic system

In the original design, the moving sieve jig has two main and auxiliary hydraulic pumping stations. Since the two hydraulic venting valves that discharge the permeable material are omitted, it is recommended that the manufacturer install the main and auxiliary hydraulic pumps. The stations merge into one hydraulic pump station.

The spring on the moving sieve jig damper is used for about 3 months under the frequent impact of the sieve bed, and it is broken. After replacing the domestic new spring, the normal use is no more than one month. In order to achieve long-term normal production, it is decided to increase the system back pressure and increase the rated working pressure of the bypass check valve from 0.3 MPa to 0.5 MPa. Thereby increasing the force load of the hydraulic cylinder, reducing the impact force of the spring, and achieving the intended purpose.

4 Conclusion

Through the application and improvement of the moving sieve drainage, the dynamic screening and drainage technology is an advanced and reliable technology for separating lump coal and vermiculite, which has a high return on investment and broad development prospects, but in specific applications, it should be noted. The following points:

(1) The optionality of raw coal, the proportion of optional grades, the purity of vermiculite and other factors are prerequisites for the selection of moving sieve jigs.

(2) try to eliminate gross coal iron and soft debris.

(3) Strive to reduce the transportation links between coal and lump coal.

(4) Equipment layout should be reserved for the maintenance space of the moving sieve jig, the auxiliary equipment connection should be compact, and the scraper conveyor should be used to transport materials.

(5) Reasonably arrange the grading screen and crusher to facilitate the optimization of product structure in the future.

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