Recently, I reread Mr. Zhao Shuyan's article Hot Issues of Dense Medium Cyclone Coal Preparation Technology, and I have to say that it is wonderful, wonderful and wonderful. Although some views are too extreme (I may not realize it), it does not prevent us from learning coal preparation technology from him. Recently, I was inspired to read a paragraph in the original.

The lower limit of effective separation of slime dense medium cyclone has already reached 0.1mm, and Epm is less than 0.10kg/L, but the indicators of many coal preparation plants are unstable. There are two reasons: first, the working pressure cannot be guaranteed; Second, the particle size of magnetite powder is too coarse.

These two reasons are known to all and will not be repeated.

3.1 Feeding pressure

The feeding pressure problem is often deliberately concealed by the post operators, which is difficult to find. In the original design, the liquid level of qualified medium bucket for slime was controlled by the diverter, and it was found that the diverter was easily damaged if it worked frequently. After the diverter is damaged, the operator will not ensure the liquid level of qualified medium bucket of coal slime and the feeding pressure of heavy medium cyclone of coal slime, so as to prevent medium from emerging. Guohua Technology has changed the process to completely solve this problem.

① I think that the staff may not know how to adjust the feeding pressure, or the designer does not consider how to maintain the slime dense medium pressure, which makes the operators unable to start.

② Guohua Technology has changed the process to completely solve this problem. They sold the car but didn't say how to improve it. It is also common sense. After all, the formula of Coca Cola can only make money by keeping it secret.

So how to ensure the feeding pressure of slime dense medium cyclone, please refer to Discussion on slime dense medium process, in which I only made a brief discussion.

3.2 Particle size of magnetite

As the three product heavy medium cyclone without desliming will not significantly reduce the separation accuracy even if the coarser magnetite is used, this problem is easier to be ignored.

① This problem is not so easy to be ignored, as we did not realize that "the separation accuracy of non desliming process is low sensitive to the coarser magnetite powder". (I didn't understand it, so I can't understand it)

② Why is the desliming process not sensitive to coarse magnetite powder? This problem is worth thinking and verifying.

③ Recently, I talked with a friend. He said that coal slime is critical to the stability of the heavy medium suspension. When there is less coal slime entering the system, the heavy medium system will become more delicate. After some factories suffered losses, they said nothing would come out of the mud. In one factory, two kinds of coal are washed separately, and the corresponding iron powder must be replaced. In other words, the viscosity of the suspension has a great influence on the separation. (From this, we can see the nature of the suspension.)

④ Why is the system delicate after desliming? I guess that desliming is likely to result in more water and less mud entering the heavy medium system, so it is difficult to grasp that too much coal mud in the suspension will run into the thin medium, which will be lost from the magnetic tail, resulting in less and less coal mud in the system, thus affecting the fluctuation of suspension viscosity, and thus affecting the separation effect. Therefore, the stability of the heavy medium system after desliming may not be good. Refer to the article "Stability of Dense Medium System".

The size of too coarse magnetite has two harms to the slime dense medium system: one is to make the effective separation size coarser; Second, the qualified medium of clean coal of raw coal dense medium cyclone, namely, the content of magnetic substance in the feed of coal slime dense medium cyclone, is too low, and the coal slime heavy medium has almost become a water medium, so the separation accuracy must be very low. Therefore, the fineness of magnetite must be guaranteed.

This section contains a large amount of information:

① Coarse magnetite powder will make the effective separation particle size coarser, which is also known, but we should pay attention to the D50 of the medium powder. (This gives us an inspiration that we must pay attention to the quality of the medium powder when purchasing the medium powder, which has a great impact on the separation. Some friends have suffered from this, and the medium consumption is extremely high, and the whole system is disordered.)

② On the premise that the medium powder is coarse and the primary separation density is low, the slime heavy medium will become the slime water medium, which will lead to the decline of separation accuracy. I didn't think of this before. When the density of the primary medium is low, the content of magnetic substance in the composite medium is not high, and the magnetite ore powder is relatively coarse. Under the concentration of the cyclone, most of the medium runs to the second section. As a result, the content of magnetic substances in the suspension in the overflow of cleaned coal is low, and then the heavy medium of coal slime becomes the medium of coal slime water. Poor sorting effect is inevitable.

For the selection of medium powder size, refer to the Important Role of Dense Medium Suspension in Separation.

Last words

Some people say that reading a good article is like tasting a glass of wine. Rereading the article "Hot Issues of Coal Preparation Technology with Dense Medium Cyclones" will give people the same feeling. To get out of the door, there must be time precipitation, experience and thought fermentation. Hide this wine cellar for the time being, read it again later and share it with you.

Similarly, I also hope that friends from the evolution of coal balls can enjoy it.