The basis of reasonable adjustment of grinding body gradation

The reasonable adjustment of the grinding body is mainly determined by the physical and chemical properties of the grinding materials, the grinding mode and the required fineness of the products and other factors. Screen residual curve analysis is an effective method to judge whether the gradation of grinding body is reasonable or not. Basis for reasonable adjustment of grinding body:

(1) grinding material particle size

When the steel ball is loaded with a certain amount, the total surface area of the small steel ball is larger than that of the large steel ball, and there are more chances to contact with the material. When the average particle size and hardness of the pulverized materials are large, the average ball diameter of the steel ball should be larger, and vice versa. Mill diameter small, the average ball diameter is also smaller. In addition, the average ball diameter of raw mill is larger than that of cement mill.

(2) easy grinding of grinding materials

The grindability of the incoming material is good, small steel ball can be selected; Easy to wear poor, you must choose a large steel ball.

(3) grinding unit volume of material through the amount

The diameter of steel ball is also related to the volume of material passing through the mill. Closed-circuit grinding, the separator back grinding coarse powder grinding unit volume of material through the amount of increase, so that the ball in the impact of a certain buffer, the amount of recycling, so the diameter of the ball to be selected larger, smaller on the contrary.

(4) grinding material fineness requirements

If the fineness of the grinding material is required to be fine, small steel ball should be selected appropriately, otherwise it will be large. (5) single silo mill generally with steel ball and no steel section; Steel balls for the front and steel sections for the back.

6 grinding body must match size, steel ball specifications usually use 3-5, steel section generally use 2-5.

7 the scale of all levels steel ball can press two end small, the principle among big cooperates, when using section of two kinds of steel, each account for half can.

8) in the premise of meeting the material particle size requirements, the average particle diameter should be as small as possible, in order to increase the contact area and the impact times per unit time, the diameter and length of the steel section is smaller than, because the radial wear is fast, the difference between the length and diameter of the steel section is 5mm.

Generally in the closed-circuit grinding, in order to reduce the phenomenon of grinding, often fill rates I warehouse above Ⅱ warehouse, make the material flow speed in the mill, appropriate increase the rate of return to powder. When the return powder rate is 100-150%, the yield is usually the highest. The return powder rate is too high, although the fineness is qualified, but the specific surface area decreases. When this change will Ⅱ warehouse fill rates higher than Ⅰ warehouse, and decrease the average ball diameter of steel ball and steel section diameter, slow speed inside, at the same time adjust the classifier, small number of blades, which reduces the return rate of powder. Taking the cement mill mentioned above as an example, the specific surface area and early strength of cement can be significantly improved by only adjusting the return powder rate of steel section gradation and powder concentrator under the condition that the output and screen residual value of the mill remain unchanged.

In the production process, with the wear and tear of steel balls and steel sections, the filling rate decreases. The first thing observed is not the decrease of the output at the station, but the increase of the return powder rate, the decrease of the specific surface area of cement, and the decrease of the compressive strength of cement 3d. When the return powder rate is too high, it will cause full grinding, which will lead to the decline of production. Therefore, it is necessary to determine whether to supplement the grinding body according to the amount of powder return rate and the size of specific surface area. Once the production of a lot of Taiwan, it should be reversed to regrade the grinding body.