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Metal Casting Technologies : September 2008
ADVERTORIAL+PLUS IMF introduces an innovating system to reclaim green sand Combined mechanical and thermal reclamation provides the answer to cores and dilution in greensand plants. O nce more IMF proves to be advanced in the sector of Foundry equipment. In fact it has studied, first in the world, a new generation system to reclaim green sand by a combined thermal and mechanical reclamation process and make the sand available as new sand for core production at a very acceptable price. Green sand reclamation: the status A perennial problem in mechanised greensand foundries producing castings with a high proportion of cores is the build-up of excess sand in the system. The continual dilution of the clay-bonded sand with core material means that excessive quantities of bentonite need to be added to maintain the desired properties. At the same time, the founder is frequently forced to remove perfectly good greensand from the system as the silos overflow, and then consign the material to landfill. The solution, of course, would be to take the excess greensand which has built up in the system and convert it back to high-quality silica sand. This material could then again be used for the production of cores. Until recently, the financial costs of such a procedure have frequently been seen as too great, despite the expense of bonding material and that of dispatching sand to landfill. IMF green sand reclamation: the process However, an economic method of recovering silica sand from greensand is at hand. Basically, this new IMF system combines pneumatic (mechanical) scrubbing, linked with efficient dust extraction, to remove the clay bond, with thermal processing to eliminate organic resins and coal dust. The result is a high- grade silica sand, perfectly suited to the production of cores. A typical layout based on this combined mechanical/thermal procedure would employ a conventional lump reducer which serves to break up sand lumps and reduce or sieve the material to a Diagram of the system. 58 www.metals.rala.com.au