Authors: Levytskyi A.P., Khmel Y.V., Dyrda V.Y.,
Kalashnikov V.A., Holovko L.H.
For ore mining and processing enterprises, with a modern deterioration in the conditions for the development of mineral deposits, the need to involve in processing ores with a reduced content of the useful component and, consequently, an increase in the volume of processing of the raw materials, it is very important to increase the productivity of the ore preparation departments and, first of all, the grinding departments. In the cost of iron ore concentrate energy for grinding ore in mills is more than 50%. It is known that the energy intensity of rocks is directly proportional to the square of strength and inversely proportional to the modulus of elasticity. It is also known that the compressive strength of the rock is about 7-10 times greater than the shear strength. Thus, if we consider the physical nature of the process of destruction, then the following principle must be observed in the technology of crushing: the destruction of the rock must be carried out by creating predominantly shear stresses.
According to world's leading firms in next 20 years, there are no more effective ways of disintegrating mineral raw materials than grinding in drum mills.
To date, mills (mainly drum-ball and self-grinding) have reached a certain limit in terms of optimal design, and their further improvement is possible mainly due to improvement of technological schemes and quality of protective lining. Lining not only protects drum from wear and dynamic loads, but also directly affects grinding process.
World experience shows: today rubber lining due to its unique properties - high durability and reliability, large dissipation of rubber energy, high wear resistance, etc. - have a distinct advantage over metal ones. Among designs of rubber linings in market of services, the liners of production of «SIC VALSA GTV» LLC - "Slab -Wave", "G.M.-Wave", "Slab-lifter" etc., are most in demand. In general, in comparison with metal lining, self-cleaning rubber lining "Slab -Wave", on ball mills of the 2nd and 3rd stages of grinding allows:
- reduce weight of lining set by more than 3-5 times and thereby increase service life of the supporting bearings;
- Reduce operating costs for installation and dismantling work to replace worn linings and reduce the risk of accidents;
- Reduce noise by 2-3 times;
- Increase utilization rate of mills by 3-5%;
- Ensure mill's specified capacity from first hours of operation;
- reduce consumption of grinding media by 6-10%;
- Reduce electricity consumption by 7-9% (in general for technological section by 10-12%);
- increase service life by 80-150%;
- increase duration of overhauls twice.
Example: Testing 2009 - 2012 (MSH 3,6 х 5,5 of the second and third stage of grinding of technological sections of ROF-1 PJSC "SEVGOK").
Table number 1
|
Technological parameters |
Stage |
G.M.-Wave |
Slab-lifter |
Slab -Wave |
|
Augmentation of predefined class (-0,056 мм), % |
2 |
23,8-24,5 |
28,7-28,9 |
28,7-28,9 |
|
3 |
10,7-11,8 |
10,7-11,8 |
17,20 |
|
|
Specific electricity consumption *, kW / ton of ore |
2 |
5,727 |
5,50 |
5,349 |
|
3 |
6,370 |
5,92 |
5,890 |
* As can be seen, specific electricity consumption in mills with rubber lining "Slab -Wave " is lower for whole test period compared to metal lining: in second stage of grinding by 7.1%, in third stage of crushing by 7.46%.
In addition, use of rubber lining in technological schemes of ore preparation allowed: to reduce specific consumption of milling bodies by 10% and to reduce specific power consumption as a whole for technological section by 10-12%. Therefore, today it becomes profitable to choose optimal design of rubber lining providing required increase in finished class, reducing energy consumption and consumption of balls, rather than betting only on cost of lining.
