There are approximately 6000 derelict and ownerless mines in South Africa. These mines pose serious possible environmental damage such as the contamination of water resources and dust that could result in reduced air quality and have a negative impact on the health of South African citizens and the environment. It is estimated that the Department of Mineral Resources (DMR) needs about R 49 billion for the rehabilitation of these mines. To prioritise rehabilitation, a thorough impact assessment of the mines must be considered.

In collaboration with the Council for Geoscience (CGS), the National Metrology Institute of South Africa (NMISA) designed a minerals content analysis method for the impact assessment of the derelict and ownerless mines. The information obtained through the method was then used to prioritise the rehabilitation of the mines by setting criteria for risk ranking. This method includes the identification of the minerals contained in the mines, quantification of these minerals and the shape (size) of the particles especially for asbestos containing sites.

The success of the minerals content analysis method developed at NMISA is attributed to its internationally comparable materials characterisation expertise and the advanced measurement equipment and analysis software available, which includes:

Optical and Electron Microscopes that provide mineral size (shape) distribution, elemental composition, and structural analysis

X-ray Diffraction analysis to identify and quantify minerals

Particle size distribution to monitor the possible effects of particle size on the environment and health

X-ray Photoelectron Spectroscopy for accurate surface analysis for benefaction processes and fault-finding exercises

Materials characterisation plays a vital role throughout the life cycle/stages of mining from the search and extraction of minerals, their beneficiation,

processing and ultimately the rehabilitation of mines. As South Africa’s custodian of the national measurement standards, NMISA plays a critical role in the development of reliable, fit-for-purpose materials measurement protocols to assist with the standardisation required to modernise the mining industry.

NMISA is part of the Department of Trade, Industry and Competition’s (dtic), family of the Technical Infrastructure (TI) Institutes, which also include the South African Bureau of Standards (SABS), National Regulator for Compulsory Specification (NRCS) and the South African National Accreditation System (SANAS), that together provides for confidence in local goods and products and allows for successful prosecution in cases of non- compliance. The accuracy of measurement results can be demonstrated by ensuring that these are traceable to the National Measurement Standards (Government Gazette No. 1131,19 October 2018) realised and maintained by the institute.

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