Things are really happening in the first quarter 2004. Firstly, Rio Tinto Coal Australia is finalising handover of the Hail Creek coal handling and preparation plant (CHPP) in Queensland. Secondly, InterTech and Dorr- Oliver Eimco are close to completing equipment deliveries for the CHPP at a mine in Novosibirsk, Russia. And thirdly, Eriez Magnetics is demonstrating a new Dry Coal Cleaner at its Erie, PA, Technology Center. As well as being important in their own right, these and other recent developments show the effects of some of today's key dynamics in the global market for coal handling and preparation technology.
Consumers and suppliers alike have been increasingly subject to intra- and extra-industrial factors affecting operational profitability. One result is that coal utilisation is now widely viewed as a holistic system from coal seam to combustion, requiring optimisation all along the line. While the resource base is theoretically massive, to maintain supply to metallurgical, power and other markets will actually necessitate more preparation. A continuing need to use lower grade resources, typically for domestic consumption, requires more efficient practice by established and new producers and throughout the coal chain. One of the potentially most significant geographic factors is the increasing proportion of available reserves located in areas where water supply is limited and dry processing is crucial. Environmental considerations also favour dry process technology. Meanwhile, coal exports resulting from sharply increasing coal utilisation in Asian markets and declining production in Europe tend to require higher quality products. In Australia, Canada, Colombia, Indonesia, Russia and South Africa, sophisticated coal preparation techniques are now employed to meet importers' quality stipulations.
Worldwide concern with the greenhouse effect and other impacts on our ecosystems requires preparation of cleaner coals in many producing countries. The major effect is an increase in cost-effective capacity for cleaning steam coal to improve combustible content. And resource depletion, sound environmental practice and improved preparation technology have combined to encourage coal recovery from both stored waste from previous operations and from ongoing waste streams at less efficient plants in established producing areas.
Within domestic coal chains in industrialised countries, regulatory and other pressures tend to restrict new investment to the upgrading of existing CHPP facilities as cost effectively as possible. So South Africa has led the way in raising the overall capacity utilisation rate, while the US industry has closed smaller plants and expanded and upgraded larger ones. Privatisation and deregulation in Poland, Russia and, especially the Ukraine slashed coal output initially but seem set to increase the use of efficient preparation as these industries restructure. India may progress similarly. In the UK the decline in output has cut the number of large-scale CHPPs but has created demand for small, mobile plants to treat small stocks and imported coal.
Dry Coal Cleaner on the US market. The machine is specifically designed to remove liberated shale from a variety of coal types over a wide range of sizes and is available as 9, 23, 91 and 182 tonne/hour units. Offering to perform separation tests for coal companies, Dan Norrgran, manager of Eriez Minerals & Materials Processing, says the company believes the Dry Coal Cleaner is well suited for initial rock removal from ROM coal prior to trucking or washing. The Cleaner uses an oscillating separating deck in combination with a vibrator and an air chamber to create a fluidised bed in the separation chamber. Within this bed the coal and waste separate sharply according to density. Two dust collection systems are fitted. Separation quality is variable through adjustments to the product feed rate, the vibration amplitude and/or frequency, and the air pressure and air flow. Eriez says capital investment is minimal, equipment layout simple, operating costs low and separation precision high. A 4.5 tonne/hour pilot scale unit is currently available at the Eriez Technical Center and the firm has complied an extensive database relating to operation and performance of the FGX Dry Coal Cleaner.
Whereas DMS has wet coal jigging on the retreat, the German firm allminer-al Aufbereitungstechnik presently has its allair-jig operating in various applications in the US, Colombia and Spain. The unit offers environmental, quality and recovery advantages in coal beneficiation, says allmineral's Andreas Horn. The fact that no process water is required, refuse removal is automatic and efficient, and no slurry handling or disposal is involved, simplifies permitting procedures. The jig reduces ash without increasing moisture content and also reduces pyrites and mercury. It achieves better product quality consistency; and it can recover the marginal coal content from the interface layers between the seam and non-coal strata as marketable product. The allair accepts feed material up to 50 mm/2' maximum and, depending on the material particle size distribution, can handle up to 100 tonnes/hour. The compact dimensions and weight mean the plant is transportable on site.
In conventional wet jigs, material stratification by particle density is achieved on a screen by pulsating water; allair jigs separate by pulsating air flowing through a layer of material already stratified by a constant air flow. The device uses several design features from the manufacturer's proven wet jig range and the jig hutch design is optimized for even air distribution. From the feed bin the feed star gate distributes material evenly across the width of the jig, at the same time excluding air. The jigging frame is equipped with two vibration drives and the screen deck is perforated stainless steel plate. Pulsed air flow, controlled by a pulse air valve, fluidises and stratifies low density coal above the higher density dilution rock. Since effective stratification is affected by feed particle size and density distribution, differing feed materials require specific jigging stroke characteristics. The allair can achieve this matching through adjustments to the vibration drive, the main and pulse air fans and the pulsation valve frequency.
Industry response to restrictions on both water supply and wet processing environmental impacts is clear. In 2003 Chinese engineers reported that, in the past four years, no less than 180 sets of the FGX Compound Dry Cleaning Reedrill. The machine, developed and manufactured by Tangshan Coal Preparation Complete Equipment Factory in collaboration with China University of Mining & Technology, has proved especially good for lignite and low-rank bituminous coals.