Study on the application of high chrome grinding balls instead of low chrome grinding balls in molybdenum ore (1)

(Liang Xinyi, Zhu Konghe, Wang Yansheng, Chen Tao, Ren Zhiguo)

Abstract: To solve the problem that the ball unit consumption is too high and the particle size of grinding products shifts to coarse size after the reformation of the grinding system and the optimization of the ball diameter ratio in a molybdenum concentrator. The comparison of chemical composition and mechanical properties between High Chrome Grinding Balls and low chrome grinding balls and the field application experiments concluded that:

1) High Chrome Balls instead of low chrome balls, grinding balls consumption by 0. 808 kg/ton down to 1.370kg/ton, the decrease rate is 54. 21%. The cost of grinding balls is saved by about USD300 000.0 per year.

2) The ball mill processing ability increase from 342.57 tons/hour to 402.6 tons/hour. This is related to the high chrome ball’s high density and low out-of-roundness.

3) Improved the grinding effect, and the content of easy-to-select grade increased and returned to the level before the reformation.

Key Words: ball mill, Improvement of ore crushing system, high-pressure grinding roller, high chrome grinding balls, low chrome grinding balls, grinding balls consumption, processing ability

DOI: 10. 3969 /j. issn. 1674-6082.2019. 04.038

The crushing system of a Molybdenum concentrator used three stages and one closed-circuit process, in which PXZ1200/160 gyratory crusher was used for coarse crushing, P890 cone crusher for medium crushing and P895 cone crusher for fine crushing. In 2017, the ore crushing process was reformed by adding a high-pressure roller mill between the original crushing and grinding systems, and expanding the particle size of the original crushing products from 12 ~ 0 mm to 25 ~ 0 mm, so as to enlarge the processing capacity of the original crushing system.

The main workshop Grinding System Adopts 1 section closed circuit grinding process, 1 #, and 2 # ball mills are MQY4.87 type and form a closed circuit with Fx710-gt 5 cyclone group, 3 # is MQY3.66 type ball mill and fx610-gt 4 cyclone group. After the high-pressure Roller Mill was put into operation in 2017, adding grinding steel balls was optimized in cooperation with the Kunming University of Science and Technology. The determined filling rate of steel balls was 43%, and the mass ratio of 80 mm, 70 mm, and 60 mm steel balls was 5∶3∶2.

1.Exist Problems

After the high-pressure Roller Mill was put into use in July 2017, the size of ore entering the mill changed greatly, see Table 1. Straight-line screening of roller products for closed-circuit grinding is shown in Fig. 1.

Table 1

Fig. 1 

It can be found from the screening analysis of feed size before and after reformation that the whole feed size of flotation operation after reformation deviates to coarse size, which has a particular influence on the flotation effect to solve this problem.