The standard of JC/t535-94 "chromium alloy casting grinding ball for building materials industry" was established in China's building materials industry in 1994.On this basis, the national standard GB/t17445-1998 "casting grinding ball" was promulgated.The specified varieties include high chromium ball, medium chromium ball, low chromium ball, chemical composition, mechanical properties, specifications and test methods of bainitic nodular cast iron ball, etc.
A good grinding ball shall have the following properties:
(a) wear resistance: adequate wear resistance to cutting wear, deformation wear and fatigue spalling wear;High hardness for cutting wear;High strain fatigue, contact fatigue and impact fatigue life are required for deformation wear and fatigue wear.
(b) good impact toughness: under the condition of repeated impact wear, it has high impact resistance and is not broken;
(c) high hardenability: ensure 100mm ball overall rot loss uniform, no loss of round;
(d) good metallurgical quality: it shall be produced according to the prescribed standard ingredients without any casting defects such as slag or sand.
Specifically, high chromium ball should be selected for rough grinding bin, and low chromium ball can be selected for fine grinding bin.For wet grinding, low chromium ball or forged steel ball should be chosen, because in the case of corrosion, the wear resistance of high chromium ball can not be fully reflected.From the consideration of wear resistance, the casting ball produced by metal mould should be selected.
How to improve the grinding effect
The ball filling system includes the quality (density, hardness, wear resistance) of the ball, the size of the ball, the filling rate of the ball and the reasonable filling.
Large density and large diameter wear - resistant steel ball when falling large impact force, wear - resistant steel ball hardness, wear resistance is strong.Therefore, for hard and coarse ore, large density and large diameter wear - resistant steel ball is needed.However, in order to effectively grind the fine ore grains and increase the number of times of the wear-resisting steel balls per unit time, wear-resisting steel balls with smaller diameter are also needed.When the filling rate is certain, the smaller the diameter of the ball is, the more balls there are, and the more times the ball is hit per unit time.
At present, China's many processing plants, regardless of the size of the ore particle size, are adding 100 mm diameter wear - resistant steel ball, which is not reasonable.Unnecessary addition of large wear - resistant steel ball, in addition to the increase in grinding grinding, but also increase wear - resistant steel ball consumption, the larger the diameter of the ball, the faster the wear.