This article describes the latest beneficiation automatic control technology that sinonine has mastered.
Part3:Flotation automatic control
Flotation is usually made up of roughing, scavenging and cleaning operations, which are made up of a series of floatation machines in series or in parallel. The pulp and air in flotation tank, fully mixing, through a series of complex physical and chemical reaction, valuable metal particles selectively adhered to the air bubbles and be carried upward into a froth layer of gas liquid solid three-phase composition, by mechanical scraping or automatic overflow has become a typical product of flotation concentrate the process as shown in figure 1. The main contents of floatation control are liquid level control, air charge control and reagent dosing control.
Fig1.Flotation automatic control flowsheet
1.Flotation liquid level control
The liquid level of the floatation machine is one of the most important technological parameters of flotation operation, and the adjustment of liquid level is also the most important work of the floatation workers. The main factors that affect the liquid level of the flotation machine include the amount of feed and the amount of circulating foam. When the feed volume or circulating foam volume fluctuates greatly, the floatation level will also fluctuate greatly. At this time, the discharge volume of the flotation machine needs to be adjusted to ensure the stability of the floatation tank level. Figure 2 shows the principle diagram of the floatation level control. The flotation liquid level detection can vary according to the type of device using ultrasonic, laser, pressure difference of different form and principle of sensor; actuator according to different flotation equipment can be used in pipe type valve or throttle device installed in the middling box; controller and conventional PID controller.
Fig2. principle diagram of the floatation level control
The liquid level control principle shown in Fig. 2 treats each flotation cell as an independent loop system, so that the PID parameters of each loop are relatively simple, which is a very practical solution. However, when the production fluctuates frequently and the control loop is not adjusted in time, the level of the whole floatation process presents a "turbulence". The flotation production index is deteriorated, and the product recovery rate is greatly reduced.
The flotation tank with buffering capacity and large inertia, in order to improve the response ability of the single level loop, the main interference factors as the input level feedforward controller, controller changes for interference factors early response, is an effective method to improve the response ability of the single level loop. As shown in Figure 3, the adjustment amount of the opening of the previous operation as the feedforward input of the current operation controller can better achieve the level stabilization of the whole floatation process.
Fig3. Feedforward control of the floatation level
2.Flotation machine air charge control
The air charge of the floatation tank should be adjusted according to the characteristics of the mineral properties and the concentration of the pulp, so as to meet the need of mineral flotation. Figure 4 gives a diagram of the control principle of the air charge in each flotation cell. The air flow meter and the regulating valve are installed on the air supply pipe for each flotation cell, and the PID control can be used.
Fig4.Flotation machine air charge control
3. Floatation froth image processing system
In the process of flotation, the contact and collision between ore particles and bubbles, the color, brightness, size, rupture and generation rate of mineralized foam reflect the degree of mineral enrichment and flotation. The flotation operation includes observing the state of foam, regulating the operating parameters such as dosage, liquid level and inflating quantity, stabilizing the flotation production, and ensuring the recovery rate and concentrate grade. Sinonine company has been carry out research on image processing technology of flotation froth, hoping to use the image processing system instead of manual inspection observation, and through the bubble characteristic quantization parameters, combined with the grade measurement, recovery index, using expert system intelligent control method such as optimizing setting for liquid level, aeration quantity and medicine value, to improve the flotation condition and increase the recovery rate and concentrate grade objective. The optimization control principle of floatation index based on the information of foam image processing is shown in 5.
Fig5. Floatation froth image processing system
Due to the variety of mineral properties and the complex mechanism of flotation, the characteristic parameters of the floatation foam should be different in different operations. The following aspects can be taken into account in the implementation of the following aspects:
1) Closely follow the operating workers to focus on bubble characteristics and corresponding method of operation, for example according to the moving speed of adjustment of inflation amount or bubble level value; the operation process of "learning" down and interval quantization, finally establish the mathematical relationship between the liquid level and the volume of bubbles and the set value of the characteristic parameters, and then replace the manual automatically adjust the volume of air charge, or liquid level.
2) The production process of mineral properties vary greatly, recommends the use of Flotation Bubble change soo feature recognition of ore properties, chemical and process automatic retrieval set formula, can greatly improve the reagent lag adjustment, avoid tracking operation ore properties change, not timely made of metal loss.
3) The flotation index is optimized by on-line analysis of grade combined with the characteristic parameters of foam.
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