(1) Working principle of high efficiency concentrator
Increasing the particle size of the solid particles in the slurry and the settling area of ​​the concentrator can increase the processing capacity of the concentrator. Adding a flocculating agent to the concentrator to agglomerate the fine particles into a mass can increase the particle size of the settled particles, and placing the inclined plate in the ordinary concentrator can increase the settlement area, shorten the sedimentation distance of the particles, and improve the concentration efficiency. The high-efficiency concentrator and the concentrator with the inclined plate show its outstanding advantages from the above two aspects. Test and industrial production show that the high-efficiency thickener has a diameter of only two-thirds to one-half of the diameter of the ordinary thickener under the same processing capacity, and the floor space is about one-ninth of that of the ordinary thickener. One quarter, and the processing capacity per unit area can be increased by several times to several tens of times.
(2) Structure of high-efficiency concentrator
The structure of the tank, the truss and the transmission part of the high-efficiency concentrator is substantially the same as that of the ordinary concentrator. The main reason for its high concentration efficiency is that there is a special feeding cylinder. There are three main types of high-efficiency concentrators commonly used abroad: Eimco-BSP, Dorr-Oliver and Enviro-Cldar. The structure of the feed cylinder of the Amcor high-efficiency concentrator is shown in Figure 1. The cylinder is divided into three vertical mechanical mixing chambers and concentric with the central vertical axis of the thickener. The slurry is fed into the exhaust system, and the brought in air is discharged, and then enters the mixing chamber through the feeding pipe, and is fully mixed with the flocculating agent, and then directly fed to the grit layer through the feeding pipe which is radially distributed in the lower part of the mixing chamber. Upper part. After the liquid is filtered through the upper layer of the grit layer, it rises into an overflow, and the floc remains in the grit layer and enters the underflow. [next]
The structure of the Doll-Oliver high-efficiency concentrator is shown in Figure 2(a). The device has a special structure of the ore cylinder, as shown in Figure 2 (b). The slurry fed to the concentrator is divided into two strands, which are respectively fed to the upper and lower annular plates of the ore cylinder, and the two flows in opposite directions, so that the shearing force caused by the ore is minimized. When a certain concentration of flocculant is uniformly mixed with the slurry after being fed into the middle of the feeding cylinder, the formed floc flows smoothly from the region where the shearing force is the smallest to the concentration in the thickener.
The structure of the Enviro type high-efficiency concentrator is shown in Figure 3. The center has a reverse cone-shaped reaction tube. The slurry flows up from the lower part of the circulation tube in the center of the reaction tube along the feeding tube, enters the reaction tube through the upper part of the circulation tube, is stirred by the rotating impeller, and is fully mixed with the flocculant. Then enter the grit layer from the bottom of the reaction tube. The solution passes through the upper portion of the grit layer and moves upward to form an overflow that enters the weir. The machine has a radial or peripheral overflow tank. [next]
(III) Industrial application of high-efficiency concentrator At present, the high-efficiency concentrator used abroad has a diameter of more than 40 meters. In the United States, Canada and Australia iron ore (concentrate and tailings), the election of coal (mainly coal tailings), uranium (acidic mine water and counter-current washing), phosphate, SO2 washing residue power plants and non-ferrous metals Widely used in industry.
The area required to treat a unit weight of solids using a high efficiency concentrator is much lower than that of a conventional concentrator. Therefore, the use of high-efficiency concentrators saves investment and reduces floor space. The cost of the added flocculant and control system can be compensated for from the savings in infrastructure costs. For example, in the hydrometallurgical plant, the investment in the automation facility was compensated for two years due to the application of the high-efficiency concentrator in the automatic control to stabilize the underflow concentration and increase the recovery rate of the washing operation.
In recent years, China's mining industry has also developed a high-efficiency concentrator. In the industrial test, the small diameter GX-3.6 high-efficiency concentrator was used to treat the tailings of iron ore beneficiation , and good results have been achieved. The test results show that when the ore concentration is 12.48%, the concentration of the condensate underflow is 26.71% and 44.45%, and the suspended matter content in the overflow is 268.89 mg/L and 266.61 mg/L, respectively. . The processing capacity per unit area is 5 times higher than that of ordinary concentrators, reaching the level of similar equipment abroad. The high-efficiency concentrator is used to treat the tailings of the concentrator, which can realize high-concentration transportation of tailings, save energy, increase the utilization rate of return water, and reduce environmental pollution. The social and economic benefits are remarkable. However, there is currently no equipment for efficient concentration of any slurry. Therefore, the current high-efficiency concentrator still cannot completely replace all ordinary concentrators. This is because the flocculant is not suitable in any case. For example, it is not advisable to use flocculants or add flocculants when subsequent operations are not economically economically viable. In addition, when the compressibility of the slurry is very poor, or the process requires the concentrator to have a large reservoir capacity and a buffering effect, and the concentration of the grit is high, it is not suitable to use a high-efficiency concentrator.
(4) Automatic control of high-efficiency concentrator
The automatic control of the concentrator increases the concentration efficiency, ensures a higher concentration of the underflow and the desired overflow, and keeps the underflow evenly discharged. The automatic control system diagram and schematic diagram of the high-efficiency concentrator are shown in Figures 4(a) and (b) respectively.
Main control items:
(1) The amount of flocculant added. By measuring and calculating the feed concentration and feed flow rate, the ratio of the solid content in the slurry to the flocculant addition amount is kept constant, and a sufficient amount of flocculant is maintained in the slurry. Changing the number of revolutions of the flocculant pump can control the amount of flocculant added.
(2) Underflow concentration and height of the compression layer. The underflow concentration is interlocked with the rotational speed of the underflow pump, and the underflow concentration is controlled by controlling the number of revolutions of the underflow pump. When the underflow concentration is high, the number of revolutions of the pump is increased, the amount of lift is increased, and the concentration of the underflow is thickened by thickening; on the contrary, the number of revolutions of the pump is reduced, the amount of lift is correspondingly reduced, and the concentration of the underflow is thickened. The pump speed remains the same only when the underflow concentration meets the requirements. There is a certain correspondence between the height of the compression zone interface and the number of revolutions of the underflow pump and the flow of the underflow, so the number of revolutions of the underflow pump must meet the requirements of these two parameters. The underflow pump keeps the underflow concentration constant between the upper and lower speeds. If the rotation speed is too large, the material in the compression zone of the thickener is easily evacuated, resulting in a decrease in the concentration of the underflow. If the rotation speed is too slow, the concentration of the underflow is increased, and the discharge is not smooth, which may cause blockage of the discharge pipe. The optimum speed of the underflow pump should control the optimum height of the compression zone interface in order to better play the role of the sediment layer.
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