Dr N Chimwani

Qualifications

2017    Masters of Business Leadership (University of South Africa)

2014    Doctor of Philosophy in Engineering (University of the Witwatersrand)

2008    ISO 9001: 2000 Quality Management System Internal Auditing

2008    OHSAS 18001 Occupational Health & Safety Management System

2008    Basic Food Hygiene and Hazard Analysis and Critical Control Point (HACCP)

2007    B-Tech (Hons) Chemical Technology (National University of Science and Technology, Zimbambwe)

2005    Quality Assurance - City and Guilds London

2004    Higher National Diploma in Chemical Engineering (National University of Science and Technology, Zimbambwe)

2002    National Diploma in Process Technology (National University of Science and Technology, Zimbambwe)

2000    National Certificate in Process Technology (National University of Science and Technology, Zimbambwe)                         

NRF Rating

Currently teaching

Dr Chimwani I am a Senior Researcher, (National Research Foundation rated researcher) at the Institute for the Development of Energy for African Sustainability (IDEAS) at the University of South Africa (UNISA). Functions includes directing operations of the mineral processing research group in line with the Institute and UNISA strategy.

Fields of academic interests

Research interests: Exploring several modelling techniques to obtain deeper understanding of the internal behaviour of size reduction units (crushers, mills cyclones), yielding insightful information that addresses or brings solution to other industrial problems.  Designing sustainable mineral processing circuits to address crisis arising from the depletion of high-grade ores and the fall of metal prices, which calls for a need to revisit the optimisation techniques with more emphasis on system approach. Expand research focus to the extraction and processing of coal since it is expected to replace oil as the world’s largest source of primary energy in few years to come, owing to its abundancy, wide distribution across the globe and affordability.

My research area is concerned with optimizing milling circuits to achieve energy efficient processes and maximizing recovery during downstream processes. My research interests focus on exploring several modelling techniques to obtain deeper understanding of the internal behaviour of size reduction units (crushers, mills cyclones), yielding insightful information that addresses or brings solution to other industrial problems.  I am also interested in designing sustainable mineral processing circuits to address crisis of the depletion of high-grade ores as well as to process tailings to create a safe environment for the communities. I intent to expand my research focus to the extraction and processing of coal since it is expected to replace oil as the world’s largest source of primary energy in few years to come, owing to its abundancy, wide distribution across the globe and affordability.

Field of Specialisation

Comminution/Mineral processing: Optimizing size reduction of ores to achieve maximum recovery during downstream processes.

Journal articles

1. Chimwani, N., Glasser, D., Hildebrandt, D., Metzger, M.J., Mulenga, F.K., 2012. Determination of the milling parameters of a platinum group minerals ore to optimize product size distribution for flotation purposes. Minerals Engineering, Volumes 43–44, April 2013, Pages 67-78.
2. Mulenga, F.K., Chimwani, N., 2013. Introduction to the use of the attainable region method in determining the optimal residence time of a ball mill. International Journal of Mineral Processing, vol. 125, pp. 39 – 50
3. Ngonidzashe Chimwani, François K. Mulenga, Diane Hildebrandt, David Glasser, Murray M. Bwalya, 2013. Scale-up of batch grinding data for simulation of industrial milling of platinum group minerals ore, Minerals Engineering Volume 63, August 2014, Pages 100-109.
4. Chimwani, N., Mulenga, F.K.., Glasser, D., Hildebrandt, D., Bwalya, M., 2014. Use of the attainable region method to simulate a full-scale ball mill with a realistic transport model, Minerals Engineering. Volume 73, 15 March 2015, Pages 116-123.
5. Ngonidzashe Chimwani, François K. Mulenga, Diane Hildebrandt., (2015).Ball size distribution for the maximum production of a narrowly-sized mill product, Powder Technology, Volume 284, Pages 12-18.
6. Chimwani, N & Hildebrandt, D., Modelling of an open mill with scalped feed for the maximum production of a desired particle size range. Particulate Science and Technology DOI: 10.1080/02726351.2017.1370048
7. Ralph Muvhiiwa, Diane Hildebrandt, Ngonidzashe Chimwani, Lwazi Ngubevana, Tonderayi Matambo., (2017). The Impact and Challenges of Sustainable Biogas Implementation Towards a Bio-based Economy. Sustainable and Society DOI 10.1186/s13705-017-0122-3
8. Thapelo Mohale, Ngonidzashe Chimwani, Murray M. Bwalya. Tailoring Ball Mill Feed Size Distribution for the Production of a Size-Graded Product. Minerals Engineering (Under Review).
9. Robert Khumalo, Ngonidzashe Chimwani. Optimisation of a combined milling and flotation circuit. Mineral Processing and Extractive Metallurgy Review (Under Review).
10. Murray M. Bwalya, Ngonidzashe Chimwani. Revisiting the dropweight model for predicting particle breakage probability. KONA Powder Technology. (Under Review)
11. Ngonidzashe Chimwani, Murray M. Bwalya. Using DEM to investigate how shell liner and end-liner profile can induce ball segregation in a ball mill. KONA Powder Technology. (Under Review)
12. Ngonidzashe Chimwani, Murray M. Bwalya. Milling studies in an impact crusher I: kinetics modelling based on Population balance modelling. KONA Powder Technology. (Under Review)

Paper presentations

• 2016 American Institute of Chemical Engineers (AIChE) Annual meeting, San Francisco, CA, USA.
• 2016 XXVIII International Mineral Processing Congress, Quebec City Convention Centre, Canada.
• 2014 American Institute of Chemical Engineers (AIChE) Annual meeting, Atlanta, GA, USA.
• South African Process Optimisation Symposium 2014.
• International Conference on Chemical Thermodynamics and the South African Institute of Chemical Engineers 2014 Conference.
• 14th Comminution Conference in Cape Town in April 2014.
• Computational Modelling ’13 Conference in Falmouth, Cornwall, UK in June 2013.
• 12th Comminution Conference in Cape Town in April 2012.
• South African Institute of Chemical Engineers 2012 Conference in Drakensberg in September 2012.

Professional positions, fellowships & awards

2017    NRF Rating Y2 (2017 – 2022)

2014    Managed to complete PhD studies in less than 2 years. (Wits University)

2013    Postgrad Merit Award (Wits University)

2013    PG-UNIV COUNCIL SCHOL (Wits University)

2006    NUST Book Prize winner for the best student (B-Tech Hons Chemical Technology)

2004    Book Prize for the best student HND Chemical engineering.

2004    Book Prize for the best project HND Chemical Engineering.