I. Introduction Liaoning Province Paishanlou gold mine is a Jicai, elections, the rule of large-scale modern gold mine. The beneficiation part adopts the whole mud cyanide carbon slurry process, which has large-scale and complicated equipment, and completely adopts the process characteristics of a single series of continuous production. At the beginning of the construction of the mine, it was designed and constructed in accordance with the principles of high efficiency, energy saving, automation and advanced. The beneficiation automation control part was commissioned exclusively by the Northeast University Automation Research Center. In 1998, it passed the acceptance of the State Economic and Trade Commission. The beneficiation process automation control system can realize real-time monitoring of the equipment, and can realize the collection, alarm and related technical parameters of the process parameters such as concentration, liquid level, material level, flow rate, pressure, temperature and pH value. Achieve efficient operation of equipment. Improve labor productivity, reduce metal loss and increase the recovery rate of mineral processing. Second, the introduction of mineral processing process The crushed ore after the ore is crushed into the MQG3245 wet lattice ball mill for rough grinding by the belt feeder and belt conveyor. The ball mill is discharged into the 2-FG2400 sorghum double helix classifier for classification; the classifier returns to the sand and returns. l The ball mill constitutes a closed circuit and grinds, and the overflow of the classifier enters the pump pool, and is fed to the φ500 hydrocyclone through the slurry pump for secondary grading; the overflow product enters the φ1500 high-efficiency thickener for pre-dip concentration; the concentrated pulp The pump is used to drive into the leaching tank, and activated carbon and sodium cyanide are added for adsorption; while the cyclone sinks into the φ3260 wet overflow ball mill for re-grinding. Its discharge into the pump pool, which constitutes a secondary closed-circuit grinding. The gold-loaded charcoal that adsorbs gold hits the desorption column for desorption. The adsorbed pulp enters the filter press. The slag after pressure filtration is transported by the belt conveyor to the dry heap of the tailings mine, and the returned return water is returned to the process. Third, the automatic control of the beneficiation process (1) Grinding system 1. Grinding system control plan Under certain grinding conditions, a section of fineness is used as the control object, and the belt feeding to the mining machine is used as the control parameter to realize the automatic control of the whole system. The automatic control block diagram is shown in Figure 1. Figure 1 Grinding system control According to the process requirements, the grinding fineness is set to a certain value, and the fineness of the grinding is detected by the particle size analyzer. The computer compares the detected value with the set value, and the deviation is calculated and output to the belt feeder motor: The ore supply to the belt is adjusted accordingly by changing the motor frequency. In order to achieve a better grinding fineness. If the fineness is high, the amount of ore added is increased, but the load of the ball mill cannot be exceeded; the fineness is low. Then reduce the amount of minerals. At the same time, the changes of the parameter curves of 1, 2 ball mill current, return sand water supply, concentration, etc. are monitored to ensure that the 1 and 2 ball mills operate within the load. According to the trend of the parameter curve, the operating system is adjusted accordingly. If the amount of returned sand is unstable, the amount of returned sand is unstable, and there will be some fluctuations in fineness and ore supply. It should be adjusted in time to achieve stable operation of the system. At the same time, the second-stage grinding classification control is used to adjust the overflow concentration of the second-stage classification as the control target. The frequency converter and water supply amount are used as control parameters. This process is also based on the on-site monitoring of the change in fineness, in order to determine the grading concentration, so that the automatic control of the two-stage grading concentration can be achieved by adjusting the opening of the water supply solenoid valve and the pump speed. The grinding process is shown in Figure 2. Figure 2 Grinding process (II) Control characteristics of grinding system Application conditions: Grinding fineness should be determined according to ore properties and process requirements; grinding equipment conditions are fixed, grading equipment and process parameters are certain. System advantages: 1. The process parameters and equipment operation changes can be monitored in real time through the computer. Equipment maintenance and process parameter adjustment are carried out according to the change situation, and automatic grinding can be realized after the system is stable. 2, through the human process indicators to explore, can establish the best control program, and can be changed and tested by computer. 3. When the system is unstable, a manual and automatic control method can be implemented to achieve a better control effect. There is a problem: 1. The exploration of the process parameters requires the technician to operate, and it takes a certain time to complete. 2. The adjustment process has a certain hysteresis. 3. The nature of the ore changes and the system feed water is unstable, which may cause system fluctuations. Manual manual intervention adjustment should be performed at this time. (2) Thick system 1. Thick system control scheme The dense system control target: 1 a certain range of ore discharge concentration to meet the leaching process requirements; 2 a dense interface within a certain height to meet the working load of the thickener, the control parameters are the flocculant addition amount and the pump rotation speed. When the feeding amount of the thickener is constant, the concentration of the mine and the interface are taken as the control targets, and the computer automatically adjusts the opening degree of the flocculant and the frequency of the inverter of the discharging motor according to the deviation between the detected value and the set value. To achieve automatic control of the target value. If the concentration is too high and the interface is low, the frequency will be increased, the amount of ore discharged will be increased, and the amount of flocculant added will be reduced accordingly; if the concentration is low and the interface is high, the amount of flocculant added will be increased, and the amount of ore discharged will be reduced. To achieve the desired concentration and interface. When the amount of feed changes, the concentration and interface also change, and the computer adjusts the amount of flocculant according to the detected data, so that the system tends to be reasonable and stable. When the computer controls the overrun. If the concentration is too high or the interface is too high, an alarm will occur and manual manual adjustment can be performed. The dense process flow and control are shown in Figure 3. Figure 3 Thick process and control 2, thick system control features Application conditions: The upper limit of the control interface should be determined according to the model of the equipment: the upper and lower limits of the concentration of the ore should be determined according to the requirements of the beneficiation process: the flocculant required to be prepared must have uniform texture and stable flow. System advantages: (1) Reduce the amount of manual control, control the concentration and the interface is accurate and stable. (2) The concentration, flow rate and interface process parameter curves can be monitored in real time. The concentration can be adjusted at any time according to the production requirements. (3) When the automatic control is not ideal, the system can implement manual manual intervention adjustment. There is a problem: (1) The field test equipment should be calibrated regularly. Make sure it is measured accurately. (2) The speed of the pump and the amount of flocculant added must be coordinated. Otherwise, the system will not work stably due to the mutual coupling of its control functions. Fourth, the conclusion The automatic control system of the gold dressing of the Paishanlou gold mine in Liaoning Province has proved through operation that the control system is reliable and technically feasible. It basically realizes the signal monitoring, information collection, related data processing and related control of the process. Especially the automatic control process in the grinding classification and thickening process. It has the characteristics of high technical level, strong operability, simple and convenient, etc. This will undoubtedly bring great economic and social benefits to the enterprise, and make the management level of the enterprise to a new level. 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