COMMINUTION AND CRUSHING a new-generation mixing mechanism . The key to the new HIGmill design is the agitator ( grinding rotors ) and grinding chamber stator rings themselves , just like the rotor and stator in a mechanical flotation cell . The heart of the flotation cell is this rotor-stator mixing mechanism , which mixes the slurry , disperses air and generates kinetic turbulent energy . Turbulence is needed in order to accelerate the particles and give them sufficient energy , so that good particle-bubble contact occurs . Similarly in a HIGmill , the GrindForce mechanism more efficiently agitates the ceramic grinding media for improved particle-media interaction .
The agitator of the first HIGmill installed in a metalliferous operation included a number of changes to the materials of construction compared to the rotors used in white minerals processing , yet the fundamental design and profile were more or less unchanged . The basic design was a flat one-piece disc with angle spoke arrangement , keyed to match the shaft , much the same as other stirred disc mills on the market today . However , Outotec ’ s design engineers were striving to develop a totally unique technology to the current market norm and set about this task , utilising the internal comminution team ’ s world class , in-house DEM capability . The DEM focused on the shear / spillage between the flat surface of a grinding disc and the media bed , plus the amount of media agitation that can be achieved by a flat disc .
The result of this work was a move away from the normal flat surface grinding discs to profiled grinding rotors with counter stator rings , together making up the GrindForce mechanism . The DEM showed with this new rotor design , the velocity of the grinding rotors and media bed in contact with the rotors would be roughly the same , dramatically reducing the shear / spillage which causes wear . A further significant benefit the DEM indicated was improved media movement with the rotors compared to flat discs . The DEM work indicated a flat grinding disc surface is not the ideal design for mixing , and the media mixing / agitation is what creates the attrition grinding in stirred mills by increasing the stress intensity and the frequency a feed particle is stressed by the media bed .
From the DEM modelling , full scale grinding rotors were produced and installed in a large metalliferrous concentrator and results monitored over an eight month period . “ The results were outstanding with our benchmark 4,000 operating hours between grinding rotor replacements being surpassed given only a third of the new GrindForce rotors required replacement after this time . The added effect of the GrindForce vane rotors on the process performance was excellent with a significant improvement in grinding efficiency to the target grind size .” This is due to the improved power transfer between the GrindForce rotor surface and the media bed mass , compared to flat surface discs . In a full scale HIGmill operation before and after the introduction of the latest GrindForce grinding rotors , only 9 of the 17 original flat discs had been replaced with GrindForce rotors .
“ Full-scale operations have proven that HIGmill performance , which is already industry leading , can be further improved along with important wear performance enhancements with the application of GrindForce rotors and stators . Now all Outotec HIGmill grinding mills are equipped with GrindForce technology which furthers the energy and wear performance gap between Outotec HIGmills and other stirred mill solutions .”
New crushing options
Last year , thyssenkrupp unveiled the huge 63-130 gyratory crusher , first at Bauma and then at MINExpo . Since then , the first two machines of thyssenkrupp ’ s new flagship in primary crushing have been ordered . For this particular project the crushers will be supplied as part of two semimobile crushing plants for a large open pit copper mine .
The new machine despite a roughly 14 % larger mantle diameter of 3.3 m weighs in much lighter than its predecessor at 490 t . Its throughput of up to 14,000 t / h is more than 30 % higher than that of the predecessor model .
The new crusher weighs less because the crushing technology specialists have said goodbye to usual design principles . “ In the past the rule of thumb was the bigger the diameter , the taller the crusher ,” says Detlef Papajewski , Head of Mineral Processing , thyssenkrupp Industrial Solutions . “ But because users
Superior ’ s new Liberty™ jaw crusher generally only need a bigger diameter to increase output , the KB 63-130 is exactly the same height as the other crushers in the 63 in series , despite the larger mantle diameter .”
The new machine sets new standards with a drive rating of 1,500 kW as well . It replaces the KB 63-114 gyratory crusher developed by thyssenkrupp in the mid-1990s , which is in operation in the world ’ s biggest gold mine in Indonesia . The 30 % increase in throughput , combined with the significant weight reduction compared with its predecessor , has been made possible by combining proven FEM calculations with advanced DEM simulation .
The housing parts are in “ fish belly design ”, known from other thyssenkrupp gyratory crushers . This special design reduces stresses in the crusher housing and increases its strength despite the optimised weight . Technical highlights of the new crusher include the rotatable countershaft assembly for setting tooth clearance , and the eccentric bearing assembly with top bevel gear . As well as allowing better balancing of the machine , the new bearing system permits a much more compact design as well as maintenance-friendly assembly and disassembly .
“ The new gyratory crusher furthermore displays the typical properties of the 63 in series . If it is used in a semi-mobile crushing plant ( SMCP ) for example , the weight of the crusher can be reduced by around 200 t prior to relocation by removing certain parts . The parts in question , such as the heavy main shaft fitted with crushing tools , can also be easily removed for maintenance purposes .”
Superior Industries has unveiled a new machinery solution for crushing applications ; the Liberty™ jaw crusher . Functioning as a primary
MARCH 2017 | International Mining