With the increasing volume of ball mill, combined with the influence of ball mill equipment structure and process configuration and other factors, the production cost of concentrator is increased and the grinding efficiency is decreased. The following mainly analyzes the reasons for the reduction of ball mill grinding efficiency, and puts forward some solutions.
Reasons for low ball mill grinding efficiency
1. Influence of equipment structure on grinding efficiency
(1) Influence of defects in central feeder
The feeding mode of ball mill is central feeding. The central feeding of ball mill means that the feeder is fixed, while the feeding end of ball mill is rotating. The two contact each other through sealant pad, which can prevent pulp backflow in ball mill. When there is a lot of slurry in the ball mill cavity, the slurry will inevitably scour the sealant pad at the bottom of the feeding end of the ball mill, which will aggravate the wear of the sealing gasket and reduce the sealing property, and the slurry will flow back out of the feeding end of the ball mill from the worn gap. In production, in order to avoid pulp backflow, it is necessary to reduce the processing capacity of ball mill, so as to reduce the slurry level inside the ball mill and reduce the pulp backflow phenomenon. In addition, it is difficult to improve the filling rate of the ball mill, which means that the amount of grinding medium involved in grinding is insufficient, the ore entering the ball mill can not be fully grinded, and the amount of return sand increases, which limits the improvement of the utilization coefficient of the ball mill, and the power consumption and ball consumption per ton will inevitably increase accordingly.
(2) Influence of ball mill discharge defects
The effective diameter of ball mill discharge center hole is 1180 mm, and the ratio of effective diameter to effective diameter is 1:3.18. When the ratio of length to diameter of the ball mill increases from 1.2:1 to 1.37:1, the operation efficiency will be reduced, and the amount of slurry stored in the mill will be large, which will affect the improvement of utilization coefficient. In order to speed up the discharge, it is necessary to reduce the grinding concentration and improve the fluidity of slurry. Too fast slurry flow rate will also interfere with the grinding effect of steel balls and affect the slurry and grinding At the same time, the contact time of medium increases the difficulty of catching ore particles by grinding medium, and increases the probability of "ball milling and ball touching ball", which is not conducive to grinding efficiency and increases ball consumption.
2. Influence of process configuration on power consumption of large ball mill
The ball mill is used as a primary grinding machine, and it forms a closed-circuit process with the classification equipment. The spiral classifier and cyclone are the main classification equipment. In the case of no natural height difference, the slurry pump is required to lift the discharge of the ball mill to the hydrocyclone. In particular, the cyclone and the primary mill form a closed-circuit grinding process. The cyclone sedimentation needs to return to the primary mill, and the slurry pump needs to be configured. The electric power of the slurry pump is several times of the motor power of the spiral classifier. The diameter and length of the ball mill are large, and there is no large spiral classifier matching with it at present. Basically, it is configured with cyclone to form grinding and classification process. The motor power of slurry pump is as high as 400kwh and the power ratio of processing capacity per ton of raw ore is more than 1.21kwh, which is one of the reasons for high power consumption of ball mill classification.
Remedial measures taken in the production process
In view of the fact that the ball mill has only 270t of raw ore per hour at the initial stage of operation and the utilization coefficient is low, a series of measures are taken to improve the processing capacity
1. The sealing device of the central feeder was improved, the wear cycle and replacement cycle of the sealant gasket were prolonged, and the phenomenon that the pulp was easy to flow out of the ore feeding end was avoided. The purpose of properly increasing the ore feeding amount and grinding concentration is realized.
2. The anti spiral height of the hollow bushing at the discharge end is increased, and the ball screen is installed at the same time. The filling rate of the ball mill is increased to nearly 42%, which makes up for the problem that the ball quantity is insufficient and the ore is hard to be broken.
3. The parameters of the cutter cage at the discharge end of the ball mill were modified to solve the problem of slurry overflow. The parameters of the cyclone were improved through experiments, which improved the classification efficiency and reduced the amount of sand returned into the ball mill.
4. Ball mills with smaller specifications are used. Due to the low speed of ball mill after large-scale, it can not achieve rapid crushing, which affects the grinding efficiency, increases the driving power and leads to the increase of mechanical energy consumption proportion. Therefore, considering the cost factor, the concentrator should select the equipment with smaller specifications and lower power consumption when selecting the ball mill.
As an indispensable grinding equipment in concentrator, the grinding efficiency of ball mill has an important impact on the reduction of production cost and the improvement of production efficiency. Therefore, the concentrator should take reasonable measures to improve the grinding efficiency of ball mill. At the same time, when purchasing ball mill, the concentrator should not only consider the price, but also the structure and performance and other factors.
As a professional manufacturer of grinding mills, Shuguang Heavy Machinery sells a variety of different types of mill equipment, including ball mills, Raymond mills, vertical mills, etc.Welcome to contact us for more details.
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