PASTE THICKENING OF TAILINGS AT THE CLERMONT COAL PREPARATION PLANT

摘要

The Clermont Coal Mine is a new mine located in the western edge of the Bowen Basin adjacentrnto the township of Clermont. The mine is owned by the Clermont Coal Joint Venture (CCJV) andrnwhen fully developed will produce 12 Mt/a of thermal coal product. The mine is being developed asrna replacement for the existing Blair Athol Coal Mine (Blair Athol) owned by the separate Blair AtholrnCoal Joint Venture (BACJV). The majority shareholder and operator of both projects is Rio TintornCoal Australia (RTCA).rnThe overburden is being stripped via a truck and shovel open pit operation utilising an in pitrncrushing and conveying (IPCC) system. The mining of the coal will be a truck and shovel open pitrnoperation. A large proportion of the coal is less than ten per cent ash in situ, and the large seamrnthicknesses allow mining with little or no out-of-seam dilution. This means that the majority of therncoal is simply sized and stockpiled.rnA 300 t/h Coal Preparation Plant (CPP) is required to treat around 10 per cent of the Run of Minern(ROM) coal to ensure that the product specification is met. This CPP uses dense medium cyclones torntreat the coarse coal fraction (-50 mm + 2 mm) and spirals to treat the fine coal fraction, (-2 mm +rn0.1 mm) with the slimes (-0.1 mm) being untreated and sent for disposal.rnAt the feasibility study stage, all rejects were to be co-disposed. Co-disposal involves the pumpingrnof all the CPP reject material together. This co-disposal would require approximately 636 ML ofrnwater per year. Initial groundwater studies had reported that this water would be available fromrnunderground sources. Further investigation showed this to be incorrect and a new philosophy hadrnto be adopted.rnA number of technologies were investigated to dewater and dispose of the reject material withrnthe final selection being a multi-slope drain and rinse screen to dewater the coarse material, a highrnfrequency screen to dewater the fine rejects and a paste thickener to recover the water from thernslimes material.rnThe Clermont CPP will be the first greenfields installation of a paste thickener in the coal industry.rnThis paper will cover the decision process in selecting the dewatering equipment and the issues thatrnwill be encountered during the construction and commissioning of the paste thickener.