Coal dust has been employed in green moulding sands since very ancient times. Several different substances and sophisticated – powder and liquid – products have been tried to replace it, without success. Its powerful peel-off action is its most interesting property at first sight, but the use of coal dust provides several other advantages. For a top quality coal dust to exert its beneficial action, it has to be ground from sea coal with a particular composition uniquely formed during specific geological ages. Coal dust employed by us is ground from suitable, constantly controlled quality sea coal, low in ash and sulphur, and high in lustrous carbon, with a constant release of volatile matter. Since proper size distribution is key to coal dust quality, we use leading-edge equipment for its most effective grinding. Our coal dust also contains a small bentonite percentage, to ensure against spontaneous combustion.
For particular needs, resins with a high lustrous carbon content may be added to coal dust. Such addition also helps reduce overall amount of coal dust required in the process. The word ‘Blend’ refers to a calibrated bentonite-coal dust mixture, where the amount of bentonite exceeds coal content. The word ‘Blend’ is normally followed by two figures, indicating coal dust and bentonite percentage, respectively. Ease-of-use blends have for many years now been employed in metal casting. Blends may also be mixed with other moulding additives to meet specific needs.