Modern Quarrying October-November 2017

PPLIER OTLIGHT OT IGHT ON ICKMAKING

MARKET PLACE

GEM augments total product offering

Goscor Earth Moving (GEM), a leading player in the compact construction market, has entered the larger excavator and roadworks equipment market through its representation of the SANY brand. This augments GEM’s total product offering, providing customers with a single option for both smaller and larger equipment, MD Barry Owen says. “We have been a leading player in the compact construction market for many years through our Bobcat range. Taking SANY on-board nowmeans that we also compete in the larger equipment market.” Part of the Goscor Group, GEM offers SANY excavators, motor graders, and rollers for the construction, mining, agri- culture, sand and stone, forestry, roadworks, and plant hire sectors. Technical Expert Simon Zhu highlights that SANY is the number one heavy-equipment brand in China, with 500 000 units supplied in 180 countries. “We expect SANY’s market share in South Africa to increase significantly as a result of the distribution agreement concluded with GEM,” Owen stresses. “Mining is recovering, and while the South African economy has been continuously weak for years, it should come to the point where it bounces back a little.” The main differentiator for SANY in the local market will be highly-competitive pricing for a world-class product, sup- plemented by increased parts-holding and full in-field ser- vice and technical back-up through GEM’s national branch structure. “We hold about R8-million worth of SANY spares at any one time, and replenish this stock on a weekly basis,” says Owen. In addition, SANY equipment has been engineered spe- cifically for African operating conditions, including features such as shorter sticks and stronger booms on its excavators for enhanced durability. Major benefits for customers are fuel savings, efficiency, user-friendly design, and reliability. Commenting on GEM’s strategy to entrench SANY in the local market, Owen highlights that the initial focus will be multiple client reference points. “Of course, one only gets these good references if one has the aftersales service to sup- port the machines. Hence our strategy is to cultivate ten to 20 customers as strong advocates of the SANY brand,” he adds. www.goscor.co.za

Trying to operate outside the boundaries of reduction ratios leads to increased wear and running costs.

Rock intrusions – a sizer and breaker problem

With coal miners moving into more difficult geological condi- tions, a detailed characterisation of the ore body is increasingly vital when specifying feeder breakers or mineral sizers, according to PC Kruger, capital sales manager at FLSmith Buffalo. “Most of the ‘easy’ coal seams in the Witbank coalfields have been mined and what remains tend to include a high level of hard rock intru- sion as well as tramp material such as steel, wood and concrete.” In particular, a stripmining of old underground bord-and-pillar mine often encounters a substantial portion of rock, which has a much higher ultimate compressive strength (UCS) than the coal. While the UCS of coal ranges from about 40 MPa to about 60 MPa, tests in theWitbank region over a number of decades, have found that some rock intrusions easilymeasure up to 210MPa in strength. He says that feeder breakers are well suited for most under- ground mining conditions where the coal is relatively soft and homogenous.“However, they are not designed to deal with high strength material. Where there are regular hard rock intrusions, you will generally opt for mineral sizers.” Another critical consideration in specifying equipment for coal processing is the principle of reduction ratios in each stage of sizing. Kruger says the ‘the rules of the game’ require that, in the primary sizing stage, the ratio between the input size of coal and the output size should be about 4:1 or 5:1. “In other words, a large chunk of material with dimensions of 1 200 mm in two or three dimension can realistically only be reduced to about 300 mm in size in the primary phase,” he says. Similarly, in the secondary sizing stage, the ratio should be 3:1, which can reduce this 300 mm coal down to 100 mm. In the tertiary sizing stage, a ratio of 2:1 is the norm, breaking the material down further to the minus 50 mm size that the end-user usually requires. “Trying to operate outside the boundaries of these reduc- tion ratios invariably leads to increased wear and running costs,” he says. “Putting over-sized material – say, larger than 150 mm material – into a tertiary sizer designed for 100 mmmaterial, pre- vents the positive ‘bite’ that breaks the product down. Instead, the size and geometry of the pieces means that they do not pass cleanly through the rotors, and cause undue wear on the rotor teeth and other components.” He emphasises that trying to reduce capital expenditure by having fewer sizing stages – and therefore less equipment – is usually false economy. With the capital cost of this equipment making up only 8% to 10% of its total cost of ownership over its lifespan, the operating cost normally outweighs any upfront saving by orders of magnitude. www.flsmidth.co.za

Taking SANY on-board now means that GEM can compete in the larger equipment market.

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MODERN QUARRYING October - November 2017