Browsing by Author "Sithole, Ntokozo Aphelele"

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    Alternative technologies for the production of high carbon ferromanganese: A techno-economic Evaluation
    (Stellenbosch : Stellenbosch University, 2020-12) Sithole, Ntokozo Aphelele; Bam, Wouter; Steenkamp, Joalet Dalene; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
    ENGLISH ABSTRACT: The manganese resource (land-based) in South Africa is currently the largest, accounting for 75% of the global resource. Ore exporting has increased from 50% of the total sales in 1997 to around 85% in 2016 and the trend seems to be increasing (Directorate Mineral Economics, 2017). Furthermore, manganese smelters have either reduced capacity or shut down completely due to operational costs. Van Zyl (2017) explored the various aspects that limit growth in the mineral value chain (Van Zyl, 2017). One of the barriers that were identified in the beneficiation of manganese is the high cost of electricity required for ore smelting. Ferromanganese in South Africa is produced using Submerged-arc furnace (SAF) technology which relies heavily on electricity during production. The current study aimed to identify and compare alternative furnace technologies that can or could produce HCFeMn. The main criterion is to substantially reduce the reliance on electricity during production. The objective of the study was to make use of a literature review in the ferromanganese industry and the ironmaking industry to identify suitable alternative furnace technologies. Alternative technologies will then be compared using a techno-economic evaluation to assess the financial performance of each furnace when compared to the current technology the SAF. The evaluation consisted of mass and energy balances of the HCFeMn process and economic models. Furthermore, the sensitivity of the economic model results in response to deviations in CAPEX and OPEX estimates was investigated. The SAF was compared to the BF that was identified in the ferromanganese industry and the COREX® that was identified in the ironmaking industry. Both technologies commercially produce FeMn and/or pig iron. The BF relies on coke and the COREX® relies on coal. Mass and energy balance model results indicate that SAF recovers the least amount of manganese at 82.8% and the COREX®recovers the most at 84.1%. Fixed capital costs make the SAF the most attractive, the COREX® and BF cost 35% and 37% more, respectively. Annual production costs per ton of alloy for the COREX® on average over the project life are over 26% lower than both furnaces. The COREX® had the highest NPV (R 11 430.46) and IRR (33.11%) with the lowest discounted payback period of 7 years. The SAF NPV was 33% lower, IRR 5.04% lower, and DPBP 1 year longer than the COREX®. The BF performed the worst financially. In all three scenarios, the COREX® yielded a positive NPV, meaning the probability of a 15% return is 1. Furthermore, manganese recoveries as low as 79.7% still yield an NPV 38% higher than the SAF base case. Sourcing of technical and economic data was a challenge, the BF model had outdated HCFeMn process data available. The COREX® has no data published for the HCFeMn process, data can be obtained from thermochemical modelling, laboratory or pilot plant scale tests. Process data specific for the COREX® could improve the quality of the model outcomes of the. Collaborations with Mintek and industry partners are recommended to obtain better quality technical and economic data.