Investigation of Spent Moulding Sand Using Thermal Treatment with Regard to the Possibility of Recovering Quartz Matrix

The ongoing sustainable reduction in natural resources is prompting companies to look for materials to reuse that were previously classified as waste. Uses are sought for them either in their existing area of use or in other areas of the economy. In many cases, this is difficult. The aim of this research is to see if there is a possibility of reusing the grain matrix, a major component of spent moulding sand that was perhaps diverted too early as waste to landfill. This study included three samples of spent moulding sand of unknown origin from landfills. A study of the collected materials was carried out to identify and characterise the impurities accumulated on the surface of the matrix grains. Sieve analyses, scanning photographs, and chemical analysis with a scanning microscope were performed. The surface morphology of the samples was assessed using a confocal microscope, and chemical composition analyses were performed using LIBS laser-induced emission spectroscopy LIBS. The thermogravimetric analysis, ignition loss, and gas formability of the tested materials were performed. The tested samples were subjected to high temperatures as the most efficient method of organic waste disposal. The analyses carried out earlier were repeated on the resulting material. It was found that only one of the tested samples, in the case of the application of thermal reclamation of spent moulding sand, allowed for obtaining a grain matrix (quartz sand) of high purity scale for reuse in the foundry industry or after further treatments in other industries. The other wastes analysed require intensive mechanical treatment, which does not guarantee, due to the shape of the grain matrix, the expected purity of the quartz sand or, in the case of intensive mechanical abrasive influences, a satisfactory grain matrix yield.