Using the dynamic sieve jig exhausting technology to improve the automation degree of coal preparation

January 29, 2020

Due to the popularization of mechanized top coal mining technology, the pinch and roof vermiculite will enter the coal, which will increase the proportion of lump coal and coal ash sharply, while the traditional jig draining, heavy medium drainage and selective crushing machine Due to the complexity of the system, large investment, narrow application range and high noise, it has been unable to adapt to the requirements of the new situation. Therefore, there is an urgent need for a lump coal discharge device with high sorting precision and simple system. The moving sieve jig was developed under this circumstance. China began to study the moving sieve jig in 1986. In 1989, the first moving sieve jig was developed and the series of moving sieve jigs was serialized. It soon became the preferred lump coal for large coal preparation plants. Main equipment for drainage equipment and thermal coal preparation plant.
First, structural characteristics and working principle
1. Structural features
The moving sieve jig consists of three parts: the main machine, the hydraulic drive system and the electric control system.
1) Host
See the schematic diagram of the main structure of the moving sieve jig. It is mainly composed of a tank body, a moving sieve mechanism, a lifting wheel device, a chute, a driving actuator and the like.
Tank: The tank is mainly used for water-containing medium, and also serves as a support for lifting wheels, moving screens, oil motors and cylinders. When the water is injected into the tank to a certain height, excess water flows out from the overflow port at the discharge end of the tank to ensure a certain level of liquid level in the tank.
Moving screen mechanism: There is a weir in front of the moving screen mechanism, and an adjustable gate is arranged at the front end of the weir to adjust the size of the opening. There is a discharge wheel below the weir, which is driven by a hydraulic motor to control the amount of discharge.
Lifting wheel device: It consists of a lifting wheel and a transmission.
A lifting plate is arranged in the lifting wheel for lifting the sorted light and heavy products from the water medium and discharging them out of the machine.
Chute: The product chute is designed as a double-layer structure, the upper layer is light product and the lower layer is heavy product.
Drive actuator: The drive actuator of the moving screen is a hydraulic cylinder, which is mounted on the main beam of the cylinder bracket; the driving actuator of the discharge wheel is a hydraulic motor, which is mounted on the tank body through the electronic control system and the hydraulic station. The valve block adjusts its motion characteristics.
2) Hydraulic drive system
The hydraulic drive system mainly consists of a fuel tank, an Oil Pump, a motor unit, a main cylinder control valve block, an oil motor control valve block, and a cooling system.
The reciprocating motion of the moving screen and the operation of the draining wheel are achieved by a hydraulic system.
The hydraulic drive system is available in two configurations. The first is to use all imported formulations. The second is to use some of the main parts imported, the other is made in China. After years of research and practice, domestic hydraulic systems have achieved considerable reliability. And the price is much cheaper.
The hydraulic system developed in China adopts the international advanced two-way cartridge valve control technology. It has the advantages of small size, high precision, convenient installation and maintenance, no leakage, etc. It can control direction, flow and pressure.
3) Electrical control system
The electric control system is the control core of the moving sieve jig. By controlling the electrical components in the hydraulic system, the coordinated movement of various parts of the equipment is realized to achieve the purpose of material sorting. The control function and reliability of the electronic control system directly affect the working performance of the moving sieve jig. Therefore, in the design of the electronic control system, based on the foreign advanced technology, it not only pays attention to the application of new technology and new devices, but also Considering the reliability of each part, it is fully functional, easy to operate, and has high reliability.
The electric control system of the moving sieve jig consists of a signal detection part, an input and output interface, an LCD touch display screen, a PLC programmable controller, and a strong electric control circuit. It mainly completes the sequence start and stop of each power component, the reciprocating motion of the moving screen and the control of the motion curve, the detection and control of the meteorite bed, the detection, display, online adjustment of the main process parameters, the sound and light alarm and display of the system fault. The control of the moving screen motion curve and the stable adjustment of the thickness of the vermiculite bed are the core control contents of the dynamic screening control system.
The operation of the system completes the movement parameters and adjustment parameter settings and alarm information by operating a touch mode display. The image is intuitive and easy to adjust. It is an advanced human-machine interface method in the field of automatic control.
1.2 Working principle
When the moving sieve jig is working, the tank body is filled with a certain height of water. The moving sieve mechanism located in the water is driven by the hydraulic cylinder to reciprocate around the pin shaft. After the raw coal is fed into the moving sieve mechanism, A bed of a certain thickness is formed on the sieve plate. When the moving sieve mechanism rises, the water medium moves downward relative to the particles. When the moving sieve mechanism descends, the water medium forms an upward flow relative to the moving sieve mechanism, and the particles interfere with sedimentation in the aqueous medium to realize stratification according to density.
In the course of work, the looseness is determined by the motion characteristics of the moving sieve mechanism. The layered light product passes over the overflow weir and falls to the rear end of the lifting wheel, which is lifted by the lifting wheel and discharged to the outside of the machine. The heavy product is discharged by the drainage wheel, falls into the front end of the lifting wheel, is lifted by the lifting wheel, and is poured into the lower layer of the chute to be discharged outside the machine. The permeable fine-grained material is discharged from the bottom discharge opening of the tank by a dewatering bucket elevator.
The schematic diagram of the moving sieve jig is shown in Figure 1.
The sorting process is as follows: The moving sieve mechanism 5 is reciprocated upward and downward around the pin shaft 13 under the driving of the hydraulic cylinder 6. After the raw coal is fed into the moving sieve mechanism, a bed layer is formed on the sieve plate 3, and the moving sieve is used for the upper and lower movements to make the bed layer loose. After multiple jigging, the materials are layered according to the density. The layered light material passes over the overflow weir 8 and falls into the rear section 10 of the lifting wheel, and is lifted by the lifting wheel and discharged into the clean coal chute 11 to be discharged outside the machine; the heavy product is discharged from the draining wheel 1 and falls into the front section of the lifting wheel In the 9th, it is lifted by the lifting wheel and discharged into the rock chute 12 to discharge the machine; the fine mesh material is dropped into the bottom of the cone and discharged by the dewatering bucket elevator.
The moving sieve jig has a large processing capacity, and the processing capacity per unit area can reach 40-70 t/h. According to the classification of many users, when sorting 300-25 mm grain-sized block raw coal, I=0.07~0.104, The quantity efficiency is 95-98%, the upper limit of the treatment granularity is high, and the sorting particle size range is wide, which is of great significance for simplifying the process of sorting or draining the lump coal. After years of research and development, the dynamic sieve jig has good reliability, strong adaptability, less auxiliary equipment, simple system, energy saving and water saving. The electricity consumption per ton of coal is only 0.3-0.45 degrees, and the circulating water volume per ton of coal is 0.3 m3. The water consumption per ton of coal is <0.1 m3, and the slime water system is simple, which can truly realize the closed cycle of washing water. As the main selection equipment, it has been widely used in the construction of new coal preparation plants and old factories, especially in the cold and water-deficient areas.
Finally, this case fully demonstrates that the dynamic sieve jig can fully improve the degree of coal preparation automation in coal preparation plants in various places, and can truly improve the automation degree of the coal preparation plant and improve the automation efficiency and automation degree of coal preparation. In particular, in this area, especially in the cold and water-deficient areas, there is a great prospect, and the degree of automation of coal preparation is used to improve the economic benefits of the coal preparation plant.
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