The metallurgical testwork for a new gold project indicated acceptable settling rates and filtration rates. The equipment was sized, and the plant constructed. Subsequently, commissioning of the thickening and filtration for dry stacking of tailings indicated serious deficiencies with the design and a much lower achievable throughput. The throughput was some 30% of design and cash flow considerations were that the project throughput was restricted by poor performance of the thickeners and tailings filtration acting as a bottleneck. Mineral Engineering Technical Services Pty Ltd was commissioned with the task of increasing filtration throughput and removing the bottleneck. For the thickeners, new flocculants were evaluated, changes to the flocculant dilution were made, and thickener underflow pump speeds were increased. An additional filter feed storage tank was installed to allow for short-term filter shutdowns. With the two belt filters, various flocculants, guar and diatomaceous earth were evaluated. Also, more permeable filter cloths were evaluated in order to increase filtration rates. The single biggest improvement achieved was with the use of coagulants. This paper describes how the task was managed and what steps were taken to achieve design throughput.
?A new trend in Brazilian iron ore beneficiation processes is the concentration of ultrafine minerals. Such minerals are currently disposed in dams or similar structures despite having a high iron content. With the development of new reagents and new concentration methods, it was possible to concentrate this type of material, however, the tailings from the concentration of these materials must still be disposed. Another upward technique in iron mining in Brazil is the disposal of filtered tailings in the tailings pile (PDR). In order to be able to dispose of ultra-thin materials in the aforementioned manner, it is necessary to perform the filtration using the press filter technology, which is the most suitable to process this type of material. In press-type filters the dewatering is somehow accomplished through the pressurization offered by the pumping system responsible for feeding the filters. The present work aims to present a case study of filtering of ultrafine tailings essentially addressing the various ways studied for feeding and pressurizing filter presses through variations between available technologies. To evaluate the best feeding method, pilot scale tests were performed to determine the specific filtering conditions of ultrafine material. Parameters such as pumping time, filtering time and total cycle time were determined from which scale-up factors were applied to enable the sizing of pumping capacity on an industrial scale. Finally, data from similar systems were used to calibrate the resistance curve of the cake and the AFT Fathom software based on Wilson's theory for mineral slurry handling was used to evaluate possible feed forms. Items such as energy consumption, pumping pressure stability, dewatering efficiency and acquisition cost will be compared.