The grinding capacity of steel balls is decided by its wear-resistant capacity and hardness, and for the hard grinding ore with great hardness and tight structure, we should add more large and heavy steel balls into the ball mill.
However, in order to make sure the efficiency of grinding fine particles and increase the impacting times within a unit interval, more small steel balls should be added.
In accordance with the standard requirements, the proportion of forged steel ball and rolling steel ball is 7.8, the proportion of steel ball and cast iron ball is 7.5, but it could be reduced to 7.1 if there were too many sand holes.
Cast iron ball contains more carbon, but the hardness doesn’t meet the requirements and there are too many sand holes and hollow balls.
Small proportion will always lead to serious broken situation.
The quality of steel balls decreases, so the grinding efficiency decreases obviously, and the efficiency of ore beneficiation will be influenced, but the single consumption of balls is increased.
So, we should choose grinding balls with great hardness and toughness, and cast steel ball and forged steel ball are much suitable.
After the calculation of suitable diameter of balls and relative granularity of feeding ore, the proportion of steel ball will be reasonably decided according to the nature of granularity of the total feeding amount ( newly-fed ore and returning ore) of the ball mill—the proportion problem of steel ball.
The procedures are:
(1) determination of the sand back than on the sand back to the ball mill to the mine sieve analysis.
Ball mill total feed size characteristics drawn curve calculated according to the results of the sieve analysis.
(2) According to the characteristic curve of total feed size and suitability of the ball diameter - to the ore particle size is calculated should be added to the proportion of different size steel balls.
(3) calculate according to the proportion of the total plus ball and the ball should be added to each level ball.