    The trough classifier is mainly used in the re-election process. The material is divided into several grades before the shaker is selected, and the feed size is generally less than 3 mm. This type of classifier is characterized by a supplementary upward flow of water that is fed to the original slurry in a direction opposite to the direction in which the ore settles. The slurry is fed into the upper chute of the classifier and enters each classifying chamber in turn. As the sectional area of ​​each classifying room increases in turn, the rising water flow decreases in turn, so that a series of coarse to fine particles are produced in the bottom part of the classifying chamber. Level product.
The trough classifier can be divided into two types: free settlement and interference settlement according to different settlement conditions.
1. The free-sinking trough-shaped hydraulic classifier is characterized in that it is classified in a low-concentration slurry having a volume concentration generally lower than 25%, and the ore particles sink at a speed close to free sedimentation, so that the classification can be performed relatively accurately according to the particle size.
Such domestic grader goes mainly tin-style free-falling trough grader, commonly known as hydraulic classification box, had been selected in our various tin-mill has been widely used in the early 1950s. The construction of the hydraulic classifying box is shown in Figure 1, which consists mainly of a sloping box, a sand bar and a bottom valve. The working principle is as follows: the slurry is fed from one end of the rectangular chute in the upper part of the tank, and the fine material overflows from the other end of the chute, and the coarse material is discharged into the taper classification chamber through the sand trap, and is discharged from the discharge port of the bottom valve. High pressure water is fed from the inlet of the bottom valve to form a graded rising water flow. The diameter of the discharge port can be made into different sizes according to the size of the grit. The amount of ore discharged can be adjusted by handwheel.
Sand barrier strip is typically made of cast iron, its role is more stable form of the classification zone. Each classifying box has sand bars of different sizes and shapes, and its sectional shape is the deformation of an equilateral triangle, generally divided into three types as shown in FIG.
The advantages of the hydraulic grading box are: simple structure, reliable operation, convenient maintenance and no power consumption. The disadvantage is that there are more fine particles in the grit, and the classification efficiency is low, generally 25%~50%. It is suitable for the treatment of materials with small particle size and fine mud content. The suitable classification granularity is 2~0.074mm, while the material with less than 0.074mm has poor classification effect. The concentration of the ore should be 18%~25%.
At present, the domestic hydraulic classification box has five specifications, the main difference is only the difference in width and the number of sand barriers. In use, the five types of classification boxes are generally connected in series from small to large, and the middle is connected by a 0.2m chute. The slurry is fed into the classification box with a small width. It is also possible to select 4-8 different classifications. The boxes are connected in series.
The hydraulic classification box produced by Ninghua Mining Machinery is shown in Figure 1, and its technical performance is listed in Table 1. The technical performance of the hydraulic classification box produced by Shicheng and Yunxi Dahao Wear-resistant Factory is shown in Tables 2 and 3.
2. Interference and settlement trough hydraulic classifier The working characteristic is that the solid concentration of the slurry in the classification zone is high, and the ore particles are classified under the condition of interference settlement. The advantages are large processing capacity, low water consumption, large product concentration and small body volume. Although the accuracy of classification by particle size is poor, in the graded product, the ore particles having a large difference in density are suitable for shaker sorting.
In this classifier, the water flow section is usually reduced by a flow reducing device (Fig. 3) consisting of a perforated plate or screen, and a large rising water velocity is formed at the bottom of the smaller section, and the top rising water velocity is higher. Small, causing the sedimentation velocity to be larger than the top rising water velocity and smaller than the bottom rising water velocity, some of the ore particles are suspended in the upper part of the contraction device to form a suspension having a large volume concentration, thus forming a stable interference sedimentation condition.
The structure of the 4-chamber mechanical agitation interference settlement hydraulic classifier commonly used in China is shown in Fig. 4. It mainly consists of a trapezoidal groove 1, four pyramidal boxes 3 and its agitator 11 with blades, transmission 2 and grading. The composition of the mining device. The four tanks are enlarged one by one from the feeding end to the overflow end, and are arranged in a stepped shape. The grading device at the bottom of each tank includes a stirring chamber 4, a grading chamber 5 (a glazing having a viewing grading process), and a pressure water chamber 6 (pressure water entering in a tangential direction). At the lower part of the classifying device there is a receiver 7 that receives the graded product. A blade agitator 11 is mounted on the lower portion of the vertical hollow shaft 12 in each of the tanks. The hollow shaft is driven by the turbine 14 to rotate the agitator at a speed of about 1.5 r/min to prevent vortex and ore deposits. The hollow shaft has a connecting rod 10 therethrough, and a lower end of the rod is fixed with a conical valve 9, and the upper end of the rod is suspended from the cam mechanism 15 on the upper side of the turbine 14. When the turbine rotates, the cam mechanism connected thereto drives the connecting rod 10 to move up and down to open and close the cone valve 9 for regular discharge, thereby ensuring discharge of a thicker product, reducing water consumption and preventing clogging. During ore discharge, the ore is first concentrated in the receiver and then discharged through the discharge port 8, which avoids the rapid flow of the slurry and affects the classification effect. The discharge amount can be controlled by adjusting the size of the discharge port and the valve 13.
The slurry is first fed into the smallest one of the classification tanks from the left chute, and is subjected to the maximum speed rising water flow to separate the coarse particles with the highest sedimentation velocity. The remaining slurry flows to the next tank, and the rising water velocity of the second classification tank is smaller than the first. The classification box separates the particles with a small settling velocity, and so on, separates several levels of decreasing particle size, and the overflow is discharged from the right chute. The classifier usually has 2 to 5 classification boxes, and the feed size is generally 2 to 3 mm, the maximum is not more than 6 mm, and the overflow particle size is about 0.25 to 1.0 mm. The concentration of the ore is about 25%, the overflow concentration is about 10% to 15%, and the concentration of the grit is up to 50%. The water consumption per ton of raw ore is 0.7~1.2m 2 . The average processing capacity is 10~25t/h, which can reach 25~30t/h when the classification accuracy is not high. When the ore size is small and requires more accurate classification, it will drop to 3~5t/h, and it is - 0.074mm material classification is poor. It is mainly used for some tungsten ore dressing plant and mercury ore dressing plant.
In addition, there is a sieve plate type (Dianval type) hydraulic classifier.
At present, the manufacturer of mechanical agitating interference sedimentation hydraulic classifiers in China only has Ningde City Gravity Selection Plant, and only produces 4-room KP-4C type, and its technical performance is listed in Table 4.
   figure 1  figure 2  image 3  Figure 4
   Table 1, 2, 3  Table 4
Extruded Solvent Recovery Activated Carbon
Extruded Solvent Recovery Activated Carbon,Spherical Activated Carbon,Column Activated Carbon,Extruded Activated Carbon
Shanxi Xinhui Activated Carbon Co.,Ltd. , https://www.adsorbac.com