Abstract
D.Phil.
We live in a world of increasing scarcity. There is limited raw natural resources, financial resources are often not enough, and acquiring land for waste disposal is getting even more difficult and costly. Government ought to set policy directions aiming for efficient use of resources based on society, keeping in mind that the end goal is to give a spotless, sound and attractive living environment to residents for present and for the future. They should likewise take a gander at how to support re-use of by-products of industrial manufacturing in other processes to make other products. The study focused on the management of waste foundry sand.
Manufacturing is the backbone of any modern economy and the foundry industry is a very crucial part of manufacturing. It provides critical inputs to most of the manufacturing sectors, with mining, automotive, and general engineering being the largest industries it supplies. Challenges faced by the industry include waste management regulations. Annual waste foundry sand generated is estimated to be 350 000 tons of Silica sand and 25 000 tons of Chromite sand. Because of the classification of spent foundry sand as a waste item, all foundry operations right now require a Waste Management License for the storage and handling of foundry sand. Waste foundry sand is classified as General Waste as well as Hazardous Waste in the National Environmental Management: Waste Act of 2008.
In this study, waste foundry sand was characterised and compared with the current legislation. All polluting elements (chromium, zinc, copper, manganese, lead, cobalt and nickel) found in the waste foundry sand were above LCT0 but below LCT1 (LCT0<LC≤LCT1). Therefore, the sand from foundries is classified as hazardous type 3 waste “low hazardous risk”. Rapid prototyping metallic concentrations were found to be lower than LCT0 and thus this waste is classified as type 4 “inert waste”. The other elements contained in the waste foundry sand such as Sodium (Na), Magnesium (Mg), Calcium (Ca), Aluminium (Al), Iron (Fe) and Silicon (Si) are not listed with corresponding leachable concentration limits (LCT) thresholds, therefore are considered to be non-perilous to human/animal wellbeing and nature.
In Germany the sand usually needs no pre-treatment since it shows a low metal leaching potential. An exceedance of the limit values may occur for materials with high organic binder content or with definite additives, such as lustrous carbon. From the results it can be recommended that the South African waste foundry sand (greensand) can be re used in other processes. Cast-iron foundries generate a huge amount of waste: a quarter to one ton of solid waste for every casting, 30–60% of...