New age castings for the iron industry
Coal dust is an additive used in greensand (clay bonded moulding sand). Most foundries add coal dust to bentonite bonded sand in order to achieve a clean, sand-free casting surface. This helps to reduce the tendency of casting failure as well as promote mould breakdown during casting shake-out. Although coal has many advantages, it is also known to cause harmful emissions such as carbon monoxide, benzene and dust especially at casting temperatures of 1350°C. A more environmentally friendly way to create moulds was therefore sought. The binder Bentonite is a clay consisting of 70-90% Montmorillonite, can be re-used in a cycle sand system and does not produce hazardous emissions. The trials using bentonite bonded sand without adding coal showed positive results. More moulding sand can remain on the casting surface and hazardous emissions can be reduced by 50% or more. Thus a cleaner and healthier working environment for the iron foundries can be created. Additionally it can reduce the contamination of sand waste making it more suitable for reuse in other industries.
