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The plant should be installed and commissioned by the coming winter. IPAS NV (Industrial Processing Activities and Systems) is an environmental engineering company with offices in Belgium, France and Poland, founded in 1987, specialised in separating primary and secondary raw materials including bottom ashes, silt-water, coal sludge, glass and sieve sands. The IMF 45 flotation system is a highly efficient separation alternative to conventional mechanical cells. The technology consists of intensive pre-aeration using a proprietary self-aspirated in-line device and subsequent froth separation in a 4.5m diameter low aspect ratio cell equipped with a variable froth crowder, and a vertical inlet distributor.

The overall residence time of a single stage separation is less than 3 minutes and due to hydrodynamic efficiency provides high selectivity, with consistent product quality concentrate. Electronic level control can be used to balance variations in feed using a tailings recycle loop. High wear components such as parts of the aerator and distributor are constructed with abrasion resistant ceramics and as the system contains no moving parts maintenance requirements are minimal. The energy for the process is provided by the variable speed centrifugal feed pump, and with total installed power of 80kW the process demonstrates a considerable saving compared with equivalent mechanical systems. The IMF V-45 will treat up to 800m3/h fine coal tailings, and was chosen by IPAS because of their previous successful application of pneumatic flotation.

Maelwgyn Mineral Services of Wales and Germany have recently provided Imhoflot pneumatic flotation systems for potash, coal, platinum and iron ore applications in Europe, South Africa and South America. MMS currently focus development on their innovative G-Cell process incorporating centrifugal froth separation, again without moving parts, and with even lower residence time of around 30 seconds. The process is seen to be the key to providing reduced infrastructure costs suitable for transportable process plants, which would allow the customer to treat small or marginal resources such as tailings ponds. In combination with another innovation - steel belt filter technology, high efficiency, relocatable fine coal and tailings process plants have already been proposed for use in South Africa and Russia.

The key objective was to to verify our scale-up predictions for hydraulic capacity. It became clear that the performance was sufficient to allow us to achieve production standards under appropriate conditions and throughputs. The benefits to a plant were clearly demonstrated by the exercise, including the simplicity of operation and the compact installation.

Maelgwyn MS and joint venture partners Ingenieria de Minerales (IDM) of Antofogasta supplied and installed Imhoflot equipment for the CMH iron ore concentrator in Huasco, Chile. The twin stream flotation plant incorporates six IMF 45 cells and treats 600 t/h of magnetic separator concentrates for removal of silicates. Test work indicated that Imhoflot technology was the most successful option to achieve final SiO2 levels of less than 1,5%. The plant incorporates a self-contained PLC and operator interface to allow full control of start-up, shutdown, flow rates and individual cell variables. Commissioning and performance testing were concluded successfully in November 2002.

Compania Minera Huasco (CMH) is a company owned by Compania Minera del Pacifico SA (CMP a 100% subsidiary of CAP SA) and MC Inversiones (a Mitsubishi group subsidiary).

Key objectives were to verify scale-up predictions for filter cake capacity and to determine the filtrate and cake qualities. It has to be said that the contribution of the CIBA polymer dispersion and conditioning was fundamental in producing asonishingly clear filtrates, and biscuit like cake from the press section. It was clear too, that the performance was consistent and reproducible, once the correct flocculant conditions were realised. Despite the ridiculously low energy input and because of large mesh apertures the water removal rate was exceedingly high. Some typical results.....