Authors: Levytskyi A.P., Khmel Y.V., Dyrda V.Y.,
Kalashnikov V.A., Holovko L.H.
Over the last three centuries, evolution of ore-grinding mills has evolved from wooden barrels with manual drive to complex structures with a drum diameter of over 14,0 m, a capacity of more than 36,000 kW and automatic control of technological processes; respectively, evolution of protection of drum from wooden beams and metal plates to modern polymer composites. Since second half of the last century rubber was used as protective lining, which was due to its unique properties: ability to large reversible deformations, large energy dissipation, abrasion-fatigue wear resistance and a high price-quality ratio index. Especially important is ability to dissipate (to absorb energy); it is this property that underlies such an important quality as resistance to fatigue and wear. Developments in the field of creating rubbers with such properties make up a significant part of costs of many world firms; usually recipe of rubbers and the technology of making lining are carefully concealed and information about them is not available in periodical literature. Therefore, number of firms that produce high-quality products in services market is generally limited.
One of leading companies in field of creating and supplying rubber lining for all existing types of ball mills is company «SIC VALSA GTV» LLC. This was facilitated by following: availability of high-tech modern equipment, development of optimal designs for lining elements, special rubber brands and professional support for operation of mills with company lining. Important in this case was also use of fundamental achievements in field of dynamics of mills and rubber mechanics. Created theory of wave abrasion and fatigue wear of rubber linings, methods of their calculation and methods of laying elements in drum allowed mechanics and technologists to create liners of "Wave" type (in market of services " Slab - Wave", " Slab - Lifter -Wave" and "GM- Wave"). According to wave theory of wear, to improve technology of crushing and increase longevity of lining, it is necessary that in drum of mill, such interaction of load and liner elements is established, at which minimum energy is expended and principle of minimum entropy production is met, i.e. minimum of disorder in system. Such harmonic interaction is achieved through use of new original lining designs such as "Wave". In addition, such liners, due to their morphometric parameters during destruction of ore, make it possible to realize predominantly shear stresses, which can significantly reduce energy consumption for disintegration of mineral raw materials, and also increase growth of finished class (-0.056 mm). In use, lining elements acquire a wave surface that is preserved almost to the point of rejection.
Slab -Wave lining provides:
• specified productivity from the first hours of operation of mill;
• preservation of wave relief to complete wear and tear, which ensures stable technological performance during entire service life;
• improvement of technological parameters of mills at all stages of grinding;
• service life of more than 30 thousand hours without replacement of lining elements.
Slab -Wave lining provides:
• specified productivity from the first hours of operation of mill;
• preservation of wave relief to complete wear and tear, which ensures stable technological performance during entire service life;
• improvement of technological parameters of mills at all stages of grinding;
• service life of more than 30 thousand hours without replacement of lining elements.
Use of such lining allowed to create new resource and energy-saving RES-technology of grinding ores in ball mills. Thanks to this technology, for example, for MSI mills 3.6 × 5.5 for the second and third stages of grinding iron ores (Northern Ore Mining and Processing Enterprise - PJSC SevGOK, Krivoy Rog, Ukraine), following results were obtained: increase in finished class increased by 17% 29%; consumption of milling bodies decreased by 10%; Specific electricity consumption as a whole for technological section decreased by 10-12%.
In comparison with metal lining, rubber lining "Slab -Wave" on ball mills of the 2nd and 3rd stages of crushing allowed: to reduce weight of lining set by more than 3-5 times and thereby to increase service life of supporting bearings, to lower operating costs for installation and dismantling work To replace worn linings and reduce risk of accidents; 2-3 times lower noise, 3-5% increase utilization rate of mills; to ensure mill's specified capacity from first hours of operation; to increase duration of overhauls twice; increase utilization rate of mills by 3-5%; for 25-30% to reduce the time of mill idle time for planned and unplanned repairs.
At present, more than 150 types of mills working with different types of ores in mining enterprises are equipped with a lining of "Slab -Wave" type produced by «SIC VALSA GTV» LLC .
In comparison with metal lining, rubber lining "Slab -Wave" on ball mills of the 2nd and 3rd stages of crushing allowed: to reduce weight of lining set by more than 3-5 times and thereby to increase service life of supporting bearings, to lower operating costs for installation and dismantling work To replace worn linings and reduce risk of accidents; 2-3 times lower noise, 3-5% increase utilization rate of mills; to ensure mill's specified capacity from first hours of operation; to increase duration of overhauls twice; increase utilization rate of mills by 3-5%; for 25-30% to reduce the time of mill idle time for planned and unplanned repairs.
At present, more than 150 types of mills working with different types of ores in mining enterprises are equipped with a lining of "Slab -Wave" type produced by «SIC VALSA GTV» LLC .
The next step in development of mill lining of Wave type of «SIC VALSA GTV» LLC . was creation of lining for first grinding stage with balls 100 mm in diameter (in perspective with a diameter of 120 mm). Here enterprise adheres to two concepts.
The first concept involves use of rubber-metal linings: to increase load-bearing capacity, metal inserts (studs) made of high-manganese steel ("G.M-Wave" lining) were vulcanized into rubber elements. At SevGOKe in MShR mill of 3.6 × 4.0, in first stage of grinding with spheres with a diameter of 100 mm, for first time in world practice of disintegration of strong iron ores, a rubber-metal lining of G.M- Wave type was installed. Test results: electricity consumption decreased by 5%; specific consumption of grinding media decreased by 5%; increase in finished product class increased by 10-12%; durability to failure over 9000 h.
The second concept involves use of combination of original brand of rubber and lining plates of large thickness such as " «SIC VALSA GTV» LLC ". In 2013, «SIC VALSA GTV» LLC started comparative industrial tests of such lining and standard metal lining produced by «SIC VALSA GTV» LLC . Lining was installed in ball mills with unloading through grate type MSHR 3,6 × 4,0 first stage of grinding. Ore-dressing factory No. 1 processes quartzite of Pervomaisk and Annovskoye mineral assets of Krivoy Rog basin. In cycle of ore preparation of first stage of grinding, steel balls with a diameter of 100 mm of third group of hardness were used. The ore charge had a particle size of 9-12% class + 20 mm.
The first concept involves use of rubber-metal linings: to increase load-bearing capacity, metal inserts (studs) made of high-manganese steel ("G.M-Wave" lining) were vulcanized into rubber elements. At SevGOKe in MShR mill of 3.6 × 4.0, in first stage of grinding with spheres with a diameter of 100 mm, for first time in world practice of disintegration of strong iron ores, a rubber-metal lining of G.M- Wave type was installed. Test results: electricity consumption decreased by 5%; specific consumption of grinding media decreased by 5%; increase in finished product class increased by 10-12%; durability to failure over 9000 h.
The second concept involves use of combination of original brand of rubber and lining plates of large thickness such as " «SIC VALSA GTV» LLC ". In 2013, «SIC VALSA GTV» LLC started comparative industrial tests of such lining and standard metal lining produced by «SIC VALSA GTV» LLC . Lining was installed in ball mills with unloading through grate type MSHR 3,6 × 4,0 first stage of grinding. Ore-dressing factory No. 1 processes quartzite of Pervomaisk and Annovskoye mineral assets of Krivoy Rog basin. In cycle of ore preparation of first stage of grinding, steel balls with a diameter of 100 mm of third group of hardness were used. The ore charge had a particle size of 9-12% class + 20 mm.
Rubber lining "H-Wave Slab" (first three rings from loading with thickness of plates 270 mm, rest - 240 mm) was installed in mill number 121, metal lining at mill No. 111. Both MWR 3.6 x 4.0 mills installed in cycle of first stage of ore preparation in one technical section No. 11-12 and operated in a closed cycle with a special classifier of type 2KSN 12,5 / 2,4.
Technological section No. 11-12 is equipped with an automated process control system that allows to work in "Optimization" mode and "Stability" mode. After launch of mill No. 121 with rubber lining, process control system of first stage of grinding was not adjusted because of a significant reduction in noise characteristics of mills: noise sensor practically did not react to the operation of mill.
During testing period for mill with rubber lining (compared to metal lined mill), following average values were obtained:
• Content of finished class - 0.056 in sink of mill increased 8-10%;
• Specific electricity consumption per ton of processed ore decreased by 7-9%;
• Ball consumption decreased by 8%.
During testing period for mill with rubber lining (compared to metal lined mill), following average values were obtained:
• Content of finished class - 0.056 in sink of mill increased 8-10%;
• Specific electricity consumption per ton of processed ore decreased by 7-9%;
• Ball consumption decreased by 8%.
Durability of rubber lining at the moment is 8 months; by calculation, total service life can be more than 10-12 months.
In Fig. 1 shows a rubber liner of type "H-Wave Slab" produced by «SIC VALSA GTV» LLC : wave character of abrasive-fatigue wear of slabs is clearly observed, which indicates correct calculation of stacking of slabs in drum. Such a wave profile of lining working surface appeared after one or two weeks and lasted for up to 8 months of operation. This ensured quality grinding of ore and optimum durability of plates within 7-8 thousand hours.
It should be emphasized that for grinding of strong polymetallic and iron ores in ball mills of first stage with spheres with a diameter of 100 mm, rubber liner "H-Wave Plate Slab" today has highest quality index and the best "price-quality" ratio.
We are ready to consider the issues of supplying rubber lining to all existing types of ball mills, as well as to develop and supply linings for disintegration of mineral raw materials.
In Fig. 1 shows a rubber liner of type "H-Wave Slab" produced by «SIC VALSA GTV» LLC : wave character of abrasive-fatigue wear of slabs is clearly observed, which indicates correct calculation of stacking of slabs in drum. Such a wave profile of lining working surface appeared after one or two weeks and lasted for up to 8 months of operation. This ensured quality grinding of ore and optimum durability of plates within 7-8 thousand hours.
It should be emphasized that for grinding of strong polymetallic and iron ores in ball mills of first stage with spheres with a diameter of 100 mm, rubber liner "H-Wave Plate Slab" today has highest quality index and the best "price-quality" ratio.
We are ready to consider the issues of supplying rubber lining to all existing types of ball mills, as well as to develop and supply linings for disintegration of mineral raw materials.
