Breakthrough for MMD sizers in hard rock applications

MMD have been manufacturing Sizers for over 40 years, processing over 80 different materials in more than 70 countries worldwide. Client placed advertorial Sizers offer a compact and efficient way of comminution in primary, secondary and tertiary stage crushing, in both underground and open pit operations. Sizers have gained notoriety in wet and sticky applications where traditional crushers have struggled. However, MMD Sizers have been developed to thrive in applications not usually deemed appropriate for their deployment. As Sizers originated in the coal industry, some believe that Sizers are only suitable for soft material processing. This is simply not the case for MMD Sizers. MMD are specialists in Sizer technology, and we have evolved Sizers to be successful in a wide range of operations, in particular hard rock applications. The additional benefits a Sizer brings, such as producing a good shaped product with minimal fines whilst also being compact, energy efficient, and maintenance friendly, make it an appealing option when it comes to selecting a machine for hard material handling. 1500 hard rock Sizer Our dedicated in-house technical development team has provided consistent research and development since the Sizer’s inception in 1980, and enabled MMD’s machines to operate successfully in a variety of industries, processing some materials rated at over 250MPa. Hard rock inclusions could be mixed with wet and sticky material without any major alteration to Sizer design or detriment to performance. Where some conventional crushers struggle to cope with sticky material, the space between Sizer teeth and the constant agitation of material within the machine prevents material build-up, this can be further enhanced where necessary by adding side cleaning combs. Ultimately, MMD Sizers can handle any combination of wet, sticky, hard or abrasive material. This is particularly useful in climates where extremes of rainfall occur throughout the seasons, effecting the characteristics of the material being processed or where material types vary across the mine site. Specialist Hard Rock Designs From the Sizer teeth design through to the drive train, the progress of these specialist heavy duty Sizers has taken many years of careful development and feature a range of adaptations to allow them to handle harder rock. Sizer teeth designed for hard rock and highly abrasive applications are engineered from upgraded material to resist wear, with additional hard facing in high impact areas. The tooth designs themselves are bulkier to ensure maximum longevity between wear component change-outs. MMD are constantly developing new tooth designs, using a combination of theoretical and physical stress testing to find ways to improve wear components. The extra forces required to break harder material also requires larger shaft diameters and heavy duty bearings. Another key feature throughout MMD’s range of Sizers is the use of in-house designed gearboxes. Using only the highest quality manufacturing processes, materials and components guarantees they are capable of dealing with the unique stresses inherent with sizing hard rock. Each machine goes through stringent design procedures to ensure the highest quality. In some instances, physical trials are performed to test sample material. Robust Ancillary Structures MMD offer turnkey solutions in the form of semi-mobile and fully mobile sizer stations. Due to the lightweight nature and balanced breaking action of the Sizer, MMD Semi-Mobile Sizer Stations for hard rock applications generally only require simple pontoon bases rather than costly heavy duty foundations and civils. However, ancillary structures still require some adaptation to matchup with the impact forces generated in hard rock applications. For example, a fully fabricated one-piece hopper hood, with a wear resistant skin rather than wear liners reduces the risk of liners falling off due to high impacts. This skin is replicated on the hopper itself, along with a T-shaped lattice design in the impact area to combat high impacts from the truck dump. Adaptations such as these ensure MMD machines are designed to endure the harsh mining environment and are built to last. MMD Sizer stations undergo rigorous FEA, DEM and Explicit Dynamics analysis at the design stage. This examination provides data on impact forces, load conditions, fatigue cycles, as well as material flow characteristics, which assist in optimising the design. This is particularly useful for wet and sticky applications where material hang-up and blockages could be problematic in features such as hoppers and chutework. At MMD, analysis and design work is undertaken by experienced, fully qualified engineers who combine their technical know-how with industry leading software to design the best solution for customer specific challenges. Case Study In 2014, MMD delivered two compact semi-mobile Sizer stations to an island in the Philippines. These bespoke designs were installed to handle lateritic nickel ore. The material within the mine is generally very sticky with hard rock inclusions, however during the wet season the material characteristics change to become extremely wet. The turnkey Sizer stations featured 625 series Sizers with side cleaning combs and D4 Apron Plate Feeders along with supporting steelwork and electrical package. Run of Mine material is directly fed by dump trucks in to the apron feeder which in turn draws material into the sizer controlled rate of up to 500TPH. Lumps of up to 800mm can enter the Sizer chamber, which is then efficiently reduced down to 150mm product. Both these machines remain active, providing trouble-free operation and minimal maintenance. Watch the unit in action: https://www.youtube.com/watch?vDSLdwNoAY80

Breakthrough for MMD sizers in hard rock applications

Industry Queensland

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