Hydraulic analysis (referred to as water analysis) is a method of indirectly measuring the particle size composition by measuring the sedimentation velocity of the particles. It is commonly used for particle size composition determination of materials less than 0.1 mm. There are three commonly used water analysis methods: gravity sedimentation method, ascending water flow method and centrifugal sedimentation method. The object to be measured is a material of less than 0.1 mm. The measurement conditions are carried out under free sedimentation conditions, and the solid volume concentration of the suspension is less than 3%, calculated according to the Stokes sedimentation velocity formula, ie Where h is the settling distance, m; Before the experiment, the ore particles with the graded particle size d are selected to settle in the water. The time required for A distance is calculated according to the Stokes formula, and then a certain amount (accurately weighed 50~100g) is formulated into a liquid-solid ratio equal to Pour 6:1 (10:1 shale material) into the glass, add water to the specified scale zero (the maximum solid volume concentration should be less than 3% after adding water), and then use a rubber head The glass rod is fully stirred. After the stirring is stopped, the slurry is allowed to settle and settled. After the calculated time interval t of the sedimentation h of the graded particle size d, the slurry of the upper part of the A is completely sucked out by the siphon. Obviously, the extracted slurry is all the ore particles with a particle size smaller than the classification particle size, but in the sediment left in the cup, there will be some mineral particles smaller than the classification particle size that cannot be sucked out, and the water should be added to the cup, then The above operation is repeated until the aspirated liquid does not contain less than the graded size of the ore. After the pulp which is sucked out is combined and dried, it is a fractional product which is less than the classified particle size in the sample. After weighing and testing the obtained fine-grained product, the content of the fraction in the sample and its grade can be marked. If several particle size analysis is required, the time t value required for the settlement h distance should be calculated separately according to the predetermined classification granularity, and the above operations are sequentially performed from fine to coarse, and all the particle sizes are completely eluted. Thus, the particle size composition of the sample can be obtained. The diameter of the graded tube is determined by the amount of water supplied and the size of the grade. If the sectional area of ​​the classification pipe is A, the water supply amount is Q, and the inner diameter of the classification pipe is D, the following relationship exists: In each of the classifying tubes, the particles having a settling velocity υ0 greater than the rising water velocity ua in the pipe settled, and the particles smaller than ua enter the next classifying pipe and are sequentially classified. The particles that remain suspended in each of the classification tubes are the critical particle size of the classification. The grit chamber of each cyclone is connected to the receiving trough with the discharge valve, and the discharge valve is closed during the test. The water is pumped out of the water tank by the water pump, and the rotor flowmeter is controlled to maintain a certain flow rate. The first flow cyclone is given through the flow control valve. Because the grit discharge valve is closed, the underflow remains at the bottom of the cone, and the overflow enters the first No. 2 cyclone. By analogy, the diameters of the overflow ports and the feed ports of the first to fifth cyclones are gradually reduced, and the grading granularity of the cyclone is gradually reduced. Therefore, after the material classification is completed, the first cyclone underflow product has the coarsest grain size, and the finest fine fraction product is the overflow of the last cyclone. Toothbrush machines are specially designed for making toothbrushes. They have compact structures and good stability, and can work at a high speed with high production output. They can finish the tasks of feeding handles, drilling holes, tufting, trimming and grinding the filaments. Haixing toothbrush machine can produce brushes with maximum three colors. And one worker can operate several machines at the same time. Toothbrush Machine, Toothbrush Making Machine, Automatic Toothbrush Machine, High Speed Toothbrush Tufting Machine, High Speed Toothbrush Making Machine Yangzhou Haixing CNC Brush Machine Co., Ltd. , https://www.hxbrushmachine.com
t — settling time, s;
Other symbols have the same meaning as before.
In order to prevent solid particles from agglomerating during the water separation, a dispersing agent such as water glass is usually added, and their concentration in water is 0.01% to 0.2%.
(1) Settling water analysis method
The simpler and more reliable method in the sedimentation method is the elutriation method. The basic principle of the elutriation method is to gradually reduce the sedimentation time from fine to coarse and gradually elute the granular materials from the sample.
The elutriation water separation device is also called Sabining sedimentation analyzer. As shown in Fig. 1, the elutriation process is carried out in a glass 1 having a diameter of 70 to 100 mm and a height of 150 to 170 mm. The cup contains a siphon 2 with a diameter of about 6~10mm. The short tube portion of the siphon should be inserted into the cup so that the lower end of the tube is 5 mm away from the surface of the solid precipitate. The other end of the siphon tube is provided with a pipe clamp 3 which is inserted into the overflow collecting tank 4.
Figure 1 elution method water analysis (Sabanning sedimentation analyzer)
1. glass; 2. siphon; 3. clip; 4. overflow receiving groove;
5. Glass holder; 6. Ruler; 7. Siphon tube holder
Let the predetermined classification granularity be d, and the free sedimentation velocity in water is Ï…0, then the time t required to settle the distance h is:
Although the particle size composition of the fine material is relatively simple and accurate by the elutriation method, it is time-consuming and labor-intensive. Therefore, the elutriation method is mostly used for checking other water analysis methods or when there is no continuous water analysis instrument.
(2) Upward water flow method
The typical device of the ascending water flow method is a continuous water separator. The basic principle is to use the same amount of rising water to produce different rising water speeds in the different diameters of the classifying tubes. The different sizes of the ore particles are divided into several according to their different settling speeds. Size. In addition to the main working part classification pipe, the water separator has a water supply device, a water glass adding device, a feeding device and an overflow receiving device. Figure 2 shows a set of four-tube water separators. [next]
Figure 2 Structure of continuous water separator
1. clear water droplet tube; 2, 7. funnel; 3. buoy; 4. water valve; 5. water glass cone bottle; 6. water glass adjustment dropper;
8. Intake central pipe; 9. Water glass liquid discharge pipe; 10. Conical cone funnel; 11. Mixer; 12. Slurry pipette;
13, 14, 15, 16 are respectively 74, 37, 19, 10 μm classification tubes; 17. Conical flasks for adjusting the liquid surface;
18. Shengming hopper funnel; 19. cone-shaped bottle of -10 μm size; 20. bubble discharge tube; 21. siphon tube;
22. slurry discharge valve; 23, 24. overflow pipe; 25, 26, 27, 28. latex tube
Each time the water sample is about 50g, it is placed in a glass cup with a stirrer. The water is filled with water in each of the graded tubes and the continuous tube before the mine. The tube clamp is opened to allow the slurry to flow into each graded tube. Under normal circumstances, the feeding time is about 1.5h. After 2h, the stirring is stopped. After about 6h, the water supply is stopped (according to whether the overflow water is clear or not). Then, the soft rubber tube at the lower end of each classification tube is clamped with a clip, and the products of each size are washed and discharged in order of thickness, and a series of treatments such as clarification, filtration, drying, weighing, and testing are performed.
The continuous water separator can obtain multi-stage products at one time, and the operation is simple. As long as the work is normal (the bubbles in the tube are released in time and the ore particles are not blocked), the obtained result is more accurate, but the water analysis time is longer.
(III) Centrifugal sedimentation method The device used in the centrifugal sedimentation method is a series cyclone classifier, also called a cyclone water separator. The basic principle is to make the classification process in the centrifugal force field. The radial settling velocity of the particles in the cyclone water separator can still be obtained by the Stokes formula, and only the centrifugal acceleration is used to replace the gravity acceleration. Its structure is shown in Figure 3. It consists of five inverted (bottom-flow vertical) hydrocyclones arranged in series and in parallel.
Figure 3 Working system of the cyclone water analyzer
The sample shall be less than 75μm, and the amount of each sample shall be less than 100g. It shall be fed from the sample container for about 30 minutes. After the classification process is completed, the bottom stream remaining in each cyclone shall be taken out for filtration, drying, weighing and assay. It can be seen that the cyclone water analyzer is faster than the continuous water separator.
Hydraulic analysis