Browsing by Author "Du Toit, De Wet"

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    A Feasibility study for cemented tungsten carbides recycling in South Africa to support investment decisions
    (Stellenbosch : Stellenbosch University, 2018-12) Du Toit, De Wet; Oosthuizen, G. A.; Sacks, N.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: This study evaluates the financial feasibility of recycling tungsten carbide in a South African context. This study is inspired by the inevitable value creation opportunities that accompanies the large amounts of tungsten carbide waste generated by the mining and tooling industry in South Africa. This is a unique waste-to-resource opportunity to deliver tungsten carbide to South Africa, as tungsten is not a widely available resource in this country, and therefore tungsten carbide must be imported for local use. The first objective of this study was to gain a thorough understanding of the different tungsten carbide recycling methods and to map these value creation opportunities. The second objective was to understand the key elements which must be considered when conducting a financial feasibility study. The third objective was to financially model a selected number of recycling methods. The final objective was to create a business case with a feasibility framework. An industrial partner, Pilot Tools (Pty) Ltd was consulted to gain general knowledge of tungsten carbide recycling plant inputs. Three recycling methods were selected and modelled financially, namely: the zinc recycling method (PRZ), the coldstream process, and acid leach method. Each of the three selected methods were modelled three times, each time at different capacities resulting in nine models. Two direct recycling methods and one indirect recycling method were chosen to model. The financial model uses a factorial method which requires the input costs of equipment, raw material, labour, utilities, and waste treatment to estimate the total manufacturing costs and capital investment needed. input from specialists, data from literature and quotations were used for the equipment costs and adjusted using the Lang factor method. From this model a ten-year net present value (NPV) analysis is done on all nine processes. A scenario analysis is conducted to determine the biggest risks of each input value to the ultimate ten-year NPV value. The NPV analysis and the scenario analysis forms the basis from which the business case is created. The final output of the study was a business case detailing when each of the recycling alternative becomes viable. This study found that all three of the recycling processes are financially feasible. The coldstream and zinc recycling processes are a much safer investment option as shown with the scenario analysis. The scaling opportunities of these two methods are also more financially viable than that of the acid leach method. Due to the nature of the problem no one ”best” option can be chosen, but the business case attempts to provide a best scenario given the decision criteria of investors. The best configuration for the zinc recycling method is the process optimised for 45.5 kg/h throughput. The process breaks even at 48.5% of maximum capacity with an IRR of 51.34% and a NPV of R127.88 million. The best configuration for the acid leach process is at 68.75 kg/h. The process breaks even at 82.50% of the maximum capacity with an IRR of 16.96% and a NPV of R72.94 million. The best configuration for the coldstream process is at 44.5 kg/h. The process breaks even at 49.50% of the maximum capacity with an IRR of 51.31% and a NPV of R131.39 million. Using the knowledge in gained in this study, a business case for tungsten carbide recycling in South Africa is created.