Metal Casting Technologies : MCT DEC 2018 (4TH QRT)
METAL Casting Technologies 4th Quarter 2018 17 make new products is open loop, as the metal can form several types of parts over time, return to the foundry and be melted into something else. Given that most metals can be recycled a large number of times, with only minimal additions made to replace lost elements from alloys, there is very little produced that cannot be recycled. Recycling all metals this way uses less virgin ores and is considerably cheaper and less energy intensive. “Foundries have been recycling metals long before the word recycling ever came into existence,” says Richard Heath, the Cast Metals Federation’s (CMF) Health, Safety & Environment Officer in the United Kingdom. “Pretty much all ferrous metals and nearly all the aluminium and magnesium alloys, and even many superalloys, come from the secondary processing of scrap from merchants.” The most common casting process used in the foundry industry is the sand cast system. Virtually all sand cast moulds for ferrous castings are of the greensand type. Greensand consists of high-quality silica sand, bentonite clay (as the binder), water and coal (a carbonaceous mould additive to improve casting finish). Typically, around one tonne of foundry sand is required for each tonne of iron or steel casting produced. With new formulations of binder materials increasing the recyclability of foundry sand, metal casters are now reusing around 100 million tonnes of sand annually. “Sand is typically recycled as many times as possible within foundries until it reaches the point of being fine,” says the CMF’s Heath. “At this point it will not work with resins (in chemically bonded sands) or will not bond with clay (in greensand).” The recycling of non-hazardous, spent foundry sand can save energy, reduce the need to mine virgin materials and may reduce costs for both producers and end users. Recycled foundry sand typically finds use in construction applications, but can also be used in the following ways: l feedstock for the manufacturing of Portland cement l partial replacement for fine aggregate in asphalt mixtures l sand required for masonry mortar mix An individual analysis of the spent foundry sand in terms of physical and chemical properties is required in order to determine the potential for recycling of foundry sand and its suitable applications. Despite the benefits of recycling sand, many small foundries still find the cost of installing reclamation units prohibitive. There is still a need, therefore, for equipment manufacturers to design and produce systems that are both practical and affordable. The drive to digitalise Today new infrastructure and industrial development is driving an increase in metal consumption – this includes various smaller-volume technical metals. The electric vehicle battery market is booming, ramping up demand for metals such as copper, nickel, cobalt, lithium, aluminum, manganese and graphite. This, in turn, is translating into increased demand for smelters and foundries. Going forwards, growing demand and market diversification means metal processors will increasingly need to digitalise if they are to meet sustainability challenges. Data is essential for solutions linking metal production from primary and recycled resources with water, emissions and other resource-consuming flows. “Today technologies are becoming increasingly interdependent, meaning that foundry system design and engineering is increasingly enabled by digitalisation,” says Kalle Härkki, head of the Metals, Energy and Water business unit at Outotec, a Finnish company designing and delivering tailored solutions for minerals and metals processing. “At Outotec we focus on improving resource efficiency in all phases of minerals and metals processing – from concentrating, smelting, metals and energy recovery to recycling and turning effluents and wastes into products,” he continues. “This means closing the materials loop with as close to zero-emission technologies as possible in primary production and secondary material processing.” While Outotec is working hard to optimise the recovery of all metals from minerals, the other challenge of resource efficiency is to maximise recovery from end-of-life batteries and other consumer products. “It is extremely important for resource efficiency to not only understand the link between mineral and metal to product and processing, but also the end-of-life product design back to metal,” says Härkki. Digitalisation-driven sustainability in the casting industry 16 www.metals.rala.com.au FEATURE CSIRO’s dry granulation technology for molten metal slag represents a sustainable, environmentally friendly and full value recovery process.
MCT SEP 2018 (3RD QRT) WHOS WHO OF METALS