GB1123591A - Sand moulding mixtures - Google Patents

Abstract

A process for the production of a sand moulding composition comprises adding to a mixture which includes sand and water an additive which is a preformed particulate solid substance which includes an absorbent solid impregnated with a liquid which is substantially non-volatile and stable at ordinary temperatures but which at high temperatures will generate a non-oxidizing atmosphere by volatilization or decomposition, the mixture or the solid substance including a proportion of clay. The solid substance itself may be clay such as bentonite, kaolin, or fuller's earth and the liquid constituent is an oil such as mineral oil e.g. crude oil or waste lubricating oil. The additive constitutes 0.5% to 20% by weight of the mixture. The mixture may also include a surface active agent such as pelleted pitch, a wetting agent and an ingredient such as tetrasodium pyrophosphate, as a pH buffering agent. To increase the gel forming properties of the clay magnesium oxide may be added. The ingredients referred to are usually combined with the additive for incorporation in the sand mixture.