After an extensive literature review by TransFIRe researchers, a number of potential applications for re-using huge quantities of Spent Foundry Sand (SFS) have been identified.
As part of Work Stream 2 of the TransFIRe project, which focusses on creating new materials and process opportunities for the foundation industries, TransFIRe researchers have been undertaking a case study focussing on potential uses of Spent Foundry Sand (SFS), a waste product of UK metals foundries leftover after the production of sand moulds or cores for casting of metals.
A literature review, carried out with input from the Cast Metals Federation, John Winter Ltd and Wm Lee Ltd, was undertaken to identify potential opportunities for re-using SFS and several applications were identified within ceramics, glass, cement, fillers in concrete and asphalt; and several others.
Although SFS can be successfully recycled and used numerous times, the sand grains eventually degrade and their ability to bind with other substances decreases and then must be separated and removed from the process. When the foundry sand becomes unfit for use in the manufacturing process, it is classed as SFS and is generally disposed of at foundry landfills or off-site municipal landfills.
According to the statistics from our industrial partner, Cast Metals Federation (CMF), the mass of spent foundry sand generated in the UK was around 200,000 tonnes per annum in 2017/18, and this figure has not changed significantly to date.
Re-use and repurposing of these wastes could not only divert them from landfills but save money on disposal and associated transport costs and CO2 emissions; and also potentially generate additional economic opportunities by creating new, low-carbon alternative raw materials, new processes and new supply chains.
Currently, only about 25% of spent foundry sand (SFS) is reused and used for limited applications worldwide, mainly by the cement industry. Accordingly, about 75%, according to some literature, of SFS is landfilled.
The physical and chemical properties of SFS depend strongly on the casting processes and the industrial sectors from which they are derived. Typically, there is some variation in the chemical composition of foundry sand from foundry to foundry and supplier to supplier. However, current research and reports on the use of SFS in the foundation industries indicate that SFS could partially replace a number of raw materials in several applications and FI production and significantly reduce the cost.
The potential technical routes and economics of applying SFS an alternative raw material in foundation industries, such as cement, ceramics, glass and more widely in the construction industry, over the use of only natural sand and other raw materials, were identified. A number of challenges and potential future research directions are also presented and a number of important future issues were identified.
The full report can be read here.
Principal authors of the report were:
Wei Deng
Paul A. Bingham
Michal P. Drewniok
Ahmed Khalil
Masoud Ahmadinia