Engineering & Mining Journal

FEB 2018

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

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WEAR PROTECTION FEBRUARY 2018 • E&MJ; 35 www.e-mj.com using Hardox wear plate and Strenx high strength steel for years, but it's the first time that we worked together with SSAB's K1 service center in Kunshan. After hav- ing the design drawings of the bucket, K1 developed the entire solution recommend- ing steel grades, thicknesses and welding procedures. We welded based on all the ready-made components provided by K1," said After-Market Service Engineer Cai Tuo of the Earthmoving Division of XCMG. After the first bucket with Hardox 450 in the main body, Hardox 400 in the side bars and Strenx 700 in the structural part of the main body had been used in the coal mine for three months (2,000 work- ing hours), a survey showed the wear loss to be 2 mm, with an original edge plate thickness of 80 mm. The service life was expected to exceed five years, compared with three years for the previous bucket. In another sector of the market, SSAB announced its new M43 hardenable steel is formulated to provide a new level of convenience, as it can be quenched in plain water without an immediate need for tempering, yet still reaches high val- ues for hardness and impact strength. SSAB said M43 can be quenched in water instead of aqueous quenching fluids or oil for a cheaper, safer and more environmentally friendly process. It saves energy and time in production and re- duces CO 2 emissions. Heat treatment re- sults in a fully martensitic, fine-grain mi- crostructure with excellent hardness to toughness ratio. SSAB M43 can reach three times higher toughness than a medi- um-alloyed chrome-vanadium or chrome- molybdenum steel. Typical hardness and toughness val- ues are 58 HRC and 25 J/cm 2 at +20°C. For even greater toughness, low-tempera- ture tempering is enough to reach great- er than 30 J/cm 2 with hardness still at a level of 56 HRC. Shearing, blanking and piercing can be performed without risk of micro-cracking, avoiding more time-con- suming and expensive processing. Another new product, introduced last year by FLSmidth, is FerroCer Impact, a wear liner material designed to help mining companies reduce production downtime. As Helgi Gudbjartsson, the global launch manager, pointed out in a blog post, in mineral processing applications, different wear liners are applied in differ- ent situations, depending on factors such as type of ore, drop height, material lump- size distribution, and angle of impact. Each wear liner has its own advantages and disadvantages. Common types in- clude hard-metal liners, heavy-duty rubber or rubber/ceramic composite liners, each with their own strength and weakness. These positive or negative character- istics have a significant impact on main- tenance procedures and costs. A general issue facing the industry is the loss in production time because of wear liners frequently needing to be replaced and the time it takes to install new liners. A typical example could be for com- mon ore such as gold, copper or nickel, with a hard impact velocity of more than 7 m/s. In such a situation, the wear liner may have an average lifetime of one or two months at most. The replacement proce- dure can take a whole shift, putting the process flow on pause for several hours resulting in significant production losses. With units of wear liners weighing be- tween 20 kg and 40 kg each, safety is also a concern. A special lifting mechanism is often needed in addition to the scaffold- ing, allowing maintenance personnel to safely access the installation points. FerroCer Impact specifically addresses the challenges related to wear liner lon- gevity and installation time as well as the safety of personnel involved, according to Gudbjartsson. A unique composite struc- ture of steel and ceramic components, FerroCer Impact provides the advantages of both ceramic and metallic materials. Combining the superior abrasion resis- tance of a ceramic with the strength, toughness and malleability of a metal, it handles hard and abrasive materials in medium- to high-impact applications. According to the company, FerroCer Impact has been shown to increase wear resistance by a factor of up to 15 times compared with traditional wear solutions, depending on the ore type and applica- tion. This allows minerals processing plants to achieve a total cost of ownership less than half that of other liners. FerroCer Impact panels are lighter and less bulky than traditional metallic liners. Each panel comprises a number of ce- ramic inserts enclosed within a matrix of cast metal. The matrix protects the more vulnerable side faces of the inserts and ensures that only the wear face of the ceramic is exposed to material impact. The tapered geometry of the ceramic in- serts and corresponding holes within the matrix act to wedge the inserts within the matrix and prevent material particles and fluids from causing them to be ejected from the matrix. This design also enables the remain- ing wear life of the ceramic inserts to be visually assessed. As the exposed surface of the insert is progressively worn away, its area and face width increase. There is a direct correlation between an insert's face width and height so that the one can be readily calculated from the other. The panels' low weight (approximately 5 kilo- grams) and compact shape make them quick and easy to install using nothing more than standard hand tools. In one nickel processing plant, the FerroCer Impact panels were installed in a conveyor discharge chute downline from the primary crusher unit where the material drops 6 m from one conveyor belt down to another. The hardness of the nickel ore is approximately 5 on the Mohs scale. During an initial measurement after installation, the plant operated for 319 days at full production of 900 mt/h with lump sizes of up to 250 mm in diameter — a significant increase from the previous liner, which had lasted less than three weeks on average. On a different site, FerroCer Impact panels were installed in a chute down- stream from the primary crusher of a gold mine where the drop height is 2 m and the lump size up to 400 mm in diameter. The previous liner type, consisting of heavy-du- ty rubber bars, typically lasted no longer than six weeks. After the first 17 weeks in operation, the wear measurements taken on-site indicated the new FerroCer pan- els would last at least another 80 weeks, giving them a tenfold service life increase over the previous liner solution. The design of FLSmidth's FerroCer Imnpact ceramic wear panels allows the remaining wear life of the ceramic inserts to be visually evaluated.

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