Fourth, flotation tank inflation control (1) The inflation flow rate of the gas pipe is kept stable by the adjusting device. Figure 12 shows a closed-loop adjustment block diagram of the flotation air flow, which has a good effect on stabilizing the aeration volume of the flotation cell. In addition, the air pressure of the gas pipe can be kept stable, which also has a certain effect on stabilizing the aeration volume of the flotation cell. In Figure 12, pressure control can be achieved by simply replacing the flow transmitter (measurement) with a pressure transmitter (measurement). (2) The flotation index is controlled by adjusting the amount of inflation of the flotation tank. This is a more common method used in the selection of factories. A control system diagram for controlling the flotation aeration amount according to the flotation concentrate flow (concentrate grade) as shown in FIG. In the copper- nickel mixed flotation stage, the set value of the concentrate flow rate is first determined according to the nickel-containing grade in the ore, and then the amount of concentrate is ensured by adjusting the aeration amount of the flotation tank. When the concentrate flow rate is decreased, the amount of inflation is increased, the tank level is increased, and the scraping amount is increased. Another control is to determine the given value of the concentrate grade according to the copper grade in the ore, and then adjust the aeration volume of the flotation tank according to the concentrate grade. When the concentrate grade is below a given value, the amount of aeration is reduced to increase the concentrate grade. This control method is more sensitive and quicker than controlling the dose, and is simpler than controlling the tank level. [next] The flotation process is more complicated, and the amount of control is affected by various factors. For example, the recovery rate depends not only on the amount of the agent added but also on the nature of the ore, but also on the level of the flotation cell. Therefore, the control of a single parameter often does not fully meet the requirements of the process. In a high-level automation plant, multi-parameter comprehensive control is usually used to obtain better results. For example, Figure 14 shows a closed-loop control consisting of three closed-loop controls, such as flow, liquid level, and dosing, and two closed-loop controls of concentrate grade, flow, and liquid level. The measured value of the concentrate grade and the given value are controlled by the algorithm I to control the dosing, and it is determined whether the adjustment of the aeration amount changes the liquid level or directly adjusts the liquid level. In the algorithm I, it is determined whether the change of the inflation amount is within the range of the floatable inflation amount, and the inflation amount is insufficient or the inflation amount is excessive, which affects the flotation effect (ie, does not affect the range of the inflation amount of the flotation). Within the selected range, it is determined to adjust the amount of inflation to change the liquid level (called fine adjustment); if it is not within the range of flotation, it is determined to adjust the liquid level (called coarse adjustment). Stabilize by fine or coarse adjustment The purpose of the concentrate grade. Algorithms II and III complete the adjustment of the aeration amount and the liquid level, respectively. Algorithm I can achieve multi-parameter integrated control, and can also achieve optimal control or adaptive control, but the control mathematical model is different. This should be selected according to the actual process requirements. The optimization control is based on the stabilization control, keeping the foam layer height and the crude zinc recovery rate of the flotation cell substantially constant or small, and then calculating the economic effect of the new copper sulfate given value according to the above formula. Control every 6 minutes until you get the best results. [next] Figure 15 shows how the control scheme works. The ore slurry is fed into the pump pool, sent from the pump pool to the overflow tank, and evenly distributed to each spiral chute through the slurry distributor. A pumping back pressure level gauge is installed in the pumping tank to transmit the pressure signal to the differential pressure transmitter. The output signal of the differential pressure transmitter is simultaneously sent to the recorder and the regulator to record the pump pool level value and adjust The amount of water fed into the pump pool is achieved by controlling the liquid level of the pump pool. Ductile Iron Sand Castings,Sand Casting,Malleable Cast Iron Sand Casting Product,Cast Iron Sand Casting Hebei Chunfeng International Trade Co., Ltd , https://www.cfcastiron.com
There are two ways to control the amount of flotation tank inflation: 
V. Multi-parameter integrated control of flotation process
6. Optimal control of the beneficiation process
Stabilization control of the beneficiation process does not result in the best economic results in the beneficiation process. Therefore, in order to achieve the best economic results in the beneficiation process, it is necessary to control (optimized control) according to the best comprehensive economic indicators.
Optimized control of the beneficiation process, two basic algorithms, namely the tuned algorithm (EVOP) and the adaptive mathematical model, are used in the concentrator. A concentrator uses an adaptive mathematical model method for optimal control in the zinc floating circuit. The optimum set value of the copper sulfate agent is controlled to maintain a high zinc concentrate grade and has a good economic effect. The economic criterion is used as the objective function to reflect the economic effects of zinc concentrate products. A regression analysis between the barium sulfate agent and the zinc grade (output variable) to determine the control algorithm for the copper sulfate setpoint:
CuSO 4 =K p {K 1i x a +I li x b -(K li-1 x a +I li-1 x b )}+K l {K li x a +I li x b +x c } ( 8)
Where K p and K 1 ——— are the proportional and integral term coefficients, respectively;
x a ——— The change in the economic effect corresponding to the Zn% increase in the coarsely selected concentrate is positive;
x b ———The value of the economic effect change corresponding to the Zn% increase in the sweeping tailings is negative;
x c ———the amount of copper sulfate used, lg/t, is negative;
K l , I l ——— to optimize the surrounding parameters, determined by the following regression analysis;
Crude concentrate concentrate Zn%=K 0 +K 1 CuSO 4
Sweeping tailings Zn%=I 0 +I l CuSO 4
Zn%———% of zinc grade.
Seven, spiral chute feeding automatic control
The spiral chute is a re-election device . In order to simplify the operation and stabilize the sorting index, the spiral chute is required to be uniform in ore, flow and concentration stable. The control solution of the magnetic solution shown in Fig. 15 ensures that the flow and concentration of the slurry in the spiral chute are constant, meeting the above requirements.
When the pump speed is fixed, if the sand pump wear is not considered, the lift will be stable. Due to the serious wear of the sand pump, an overflow tank is added to compensate for the change of the sand pump before and after the wear of the sand pump. That is, when the sand pump is not worn, the lift is large, and the excess slurry is returned through the overflow, and gradually with the sand pump. Wear, the amount of lift is gradually reduced, and the amount of return is also reduced. In a relatively short period of time, the amount of circulating slurry returned can be considered as a fixed value. The amount of slurry discharged from the overflow trough to the spiral chute is stable, and the diameter of the discharge port can be determined according to the required amount of slurry and the height of the overflow trough. The slurry distributor divides the slurry evenly into several equal parts. A plurality of slurry cutters are installed between the slurry distributor and each of the spiral chutes, and the flow direction of the slurry can be changed as needed: either into the spiral chute or returned to the pump pool through the pipe. The number of cutters can be determined based on the fluctuation range of the slurry flow rate and concentration. Due to the use of a rotary slurry distributor, the slurry distribution is relatively uniform. Therefore, a concentration measuring cylinder is installed between the distributor and a spiral chute, and the measured slurry concentration is sufficiently representative. The slurry flow rate in the concentration measuring cylinder should be smooth without rotation. The density of the slurry was measured by a gas-blown differential pressure densitometer and converted to a slurry concentration. The change of the pulp density is converted into a pressure signal and sent to the positive and negative pressure chambers of the differential pressure transmitter. The output signal of the differential pressure transmitter is simultaneously sent to the ribbon indicator and the recorder for indication and recording. The ribbon indicator has an upper and lower limit alarm. When the slurry concentration exceeds the maximum allowable value, the ribbon indicator will emit a high signal. At this time, the spiral chute below the cutter will be put into operation, and this part of the slurry will not return to the pump. The pool cycle reduces the level of the sand pump pool and the level control system increases the water supply. After a set of slurry cutters are actuated, if the slurry concentration still exceeds the maximum allowable value, the second, third, and... cutters will act in succession until the slurry concentration returns to the allowable range. Conversely, if the slurry concentration is lower than the allowable minimum value, the ribbon indicator will emit a low signal, and the program controller will cause the set of pulp cutters to be in the low position through the actuator, at which time the spiral chute below the cutter stops working. This part of the slurry will be returned to the pump pool. After a set of slurry cutters are actuated, if the slurry concentration is still below the minimum allowable value, the second, third, ... cutters will move in succession until the slurry concentration returns to the allowable range.
It can be seen from the above that the slurry flow rate through the slurry distributor is stable, but with the different pulp concentration, the pulp cutter is at a high or low position, the number of working tables of the spiral chute is also different, and the amount of slurry returned to the pump pool is also changed. The amount of water supplied to the pumping tank is adjusted by the liquid level detecting control system to stabilize the concentration of the slurry fed into the spiral chute within the required range.