Matters needing attention of pre-grinding technology in Grinding System
In recent years, with the introduction, digestion, and absorption of much foreign advanced equipment and technology, a new domestic pre-grinding equipment manufacturing upsurge has appeared. PEX crusher, PCXL crusher, PCX crusher, PLJ crusher, SCP crusher, and PSL crusher have been used in the vertical kiln.
Ball mill is a low energy utilization rate of grinding equipment, especially the grinding body to throw off the state-based warehouse. It is very effective to use other grinding equipment with high energy utilization rate to replace the work of ball mill.
The pre-grinding process flow according to pre-grinding material to divide, process flow can be divided into pre-grinding of a single material and pre-grinding of ingredients. The former is to reduce the particle size of a single material, while the latter not only reduces the particle size of the material but also further homogenize the ingredients of the mixture, which is beneficial to the high quality and high yield of grinding products.
Pre-comminution of either single material or batch can be divided into open-circuit and closed-circuit processes. Similar to the common grinding process, the open circuit process is simple and one-time investment, but the product size fluctuates greatly, which limits the energy-saving and high-yield of the ball mill The closed circuit flow is more complex and the equipment investment is more, but the product granularity is even, the fineness is easy to adjust and control Is more conducive to the grinding body grading optimization and ball mill of high quality, energy saving, high yield.
When using extrusion machine (roller press) as pre-crushing equipment, it is more important to choose closed circuit flow. Because, domestic extruder discharge has not been really extrusion of leakage, accounting for about 15% of the total. The physical properties (particle size, grindability, etc.) of the extrudate are different from those of the extrudate, which has an obvious influence on the output and quality of the ball mill. Therefore, it is necessary to choose a pre-comminution closed-circuit flow between the dispersing classifier and extruder. The loose classifier can select the leaking material and the coarse material whose particle size is not up to standard. When it returns to the feed bin of the Extruder, it not only solves the negative influence of the edge effect (material leakage) of the extruder, but also relieves the demand of over-saturated feeding of the extruder At the same time, depending on the pre-comminuted products, the extrusion machine can use “low-pressure large cycle” operation mechanism, to reduce roll surface wear, improve the safe operation rate, extend the service life of the equipment.
When the pre-grinding process is added to the grinding system of the ball mill, the grinding parameters must be adjusted in time.
Reduce the average diameter of each bin while maintaining the same load. 605 mm is suitable for one warehouse. If the abrasive grain size is equal, the large steel ball should be picked out. If the abrasive grain size is not equal, the large ball should be reduced and the small ball with the same loading should be added.
Therefore, according to the sieve analysis curve in the mill, the position of the partition board is moved to the direction of the grinding head, which is helpful to keep the balance of grinding speed and the matching of the positions.
After pre-comminution, not only the particle size is reduced, but also the grindability is improved to some extent, which leads to a more fine powder and more content in the raw material. For this reason, the fineness of the grinding material should be adjusted from the original R0.0840% 3% to R0.0830% 3 %.
SYSTEM CYCLE LOAD RATE
In order to increase the circle flow grinding system of pre-grinding process, the high efficient powder separator should be selected to finish the product classification, reduce the amount of coarse powder and increase the amount of fine powder. The cycle load rate of the system should be controlled below 100 %. The high efficiency of the ball mill can save energy and increase output.
When choosing fine crusher, want to see its structure first, working principle is advanced. After the material enters the crusher, whether the movement track is reasonable, whether the compound comminution can be realized in the crushing cavity. Then, it must consider whether the electricity consumption per unit output is economic, whether the metal consumption is low, whether the environmental protection index can meet the standard. In a word, the product reliability and technical advancement should be well unified. In addition, extruders (Roller Press), Vertical Mill, rod mill can also be used as pre-crushing equipment, the effect is very good.