Due to the presence of large area single thickener, and the slurry pump to be repeatedly sent to Yang et al., So many mineral processing plant are two to five thickener assembled into a multilayer thickener used. The most complicated construction of the multi-layer thickener is the mud seal groove (or the interlayer gate), and its structure is shown in Fig. 5. It can be seen from the figure that the mud sealing groove is fixed on the layer spacing groove of the intermediate layer to prevent the upper layer slurry from flowing directly to the lower layer and blocking the overflow of the next layer from returning to the upper layer. [next] The most critical part of the mud seal is the discharge gap, which is the distance between the inner and outer scrapers and the lower end of the mud seal and the mud seal. This gap is very important. If the gap is too small, the ore supply is larger than the discharge amount, which causes the thick machine to accumulate. When it is serious, the mud seal is blocked. If the gap is too large, there is no accumulation around the mud seal. It was quickly drained, causing excessive discharge. If the concentration is too small, the mud sealing tank will not function as a mud seal, and the layers will become integrated, and the lower layer overflow will also flow from the mud sealing tank to the upper layer, thereby affecting the washing effect. Therefore, the discharge clearance should generally be controlled between 25 and 60 mm. When the treatment of the ore is small, a small value can be taken, and vice versa. In the late 1970s, a new type of high-efficiency thickener was installed at the Elandsrand gold mine in South Africa, the Silver King Company in Nevada and the Houston International Mining Company. The Love Landsland gold ore body uses it to collapse the slurry that overflows from the cyclone, while the Silver King and Haustown Company use the countercurrent decantation washing of the slurry. Because the efficiency of the thickener is 10 times or even 20~30 times higher than that of the ordinary thickener, it has the advantages of small area, low investment, high efficiency, low energy consumption, and easy automatic control. Since its application has been expanding, it has been widely used in concentrates, washing of tailings pulp and concentration of mud, and has a tendency to gradually replace conventional thickeners. Speciality Silicones,Linear Polysiloxane Compounds,Silicone Oil For Treadmill,Silicone Oil For Lubricant Henan Minmetals East New Materials CO. LTD. , https://www.minmetals-east.com
Multi-stage countercurrent washing consisting of multiple single-layer thickeners in series, which is characterized in that each thickener is flat on the ground, so the floor space is large, the capital cost is high, and the slurry between the thickener and the thickener It must be connected with the overflow pump by sand pump or water pump, with many equipments, inconvenient management and high power consumption. However, the operation is simple, the concentration of the discharge of each thickener is easy to control, the clarification effect is good, the washing efficiency is high, and it is not easy to cause an accident, and even if an accident occurs, a plurality of thickeners are easy to handle.
Thickeners used in washing operations in domestic cyanide plants generally use multi-layer thickeners, especially in three-layer applications, but also in double-layer and four-layer. Some are used in combination with single and multi-layer, and some are used in combination with several multi-layer thickeners. The multi-layer thickener is characterized by simple structure, small floor space, convenient operation and management, low power consumption and good washing effect. However, in addition to the lower layer of ore discharge concentration can be controlled by the work, the pulp concentration of the other layers is not easy to control, and the required grain size should not be too thick, and should be uniform, the ore amount should be as balanced as possible, otherwise it is easy to block the discharge port.
As can be seen from Fig. 4, the slurry flow direction is fed from the upper layer, and finally discharged from the lower layer through the middle layer. The additional wash water is fed from the lower layer, and the lower layer overflow is pressed into the wash water conditioning tank by the extrusion of the lower layer slurry, and then flows into the middle layer as a wash water. The same layer of overflow is pressed into the wash water conditioning tank, and then the upper layer is washed. The overflow of the upper layer is the noble liquid. This is the three-stage countercurrent washing process of the three-layer thickener. 
Many of the gold selection plants in China are commonly used in 2-3 layer thickeners. The continuous washing process of a three-layer thickener in a cyanide plant is shown in Fig. 6. The ore size of the plant used for cyanidation is 88% -0.037mm, the mass fraction of ore gold is 27.8%, and the ore discharge is 57.72%. The washing recovery rate was 98.86%.