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  • World Leader in New Steel Research Visits the University of Pretoria

    world leader11dec17

    Photo: Prof Roelf Mostert, Sir Prof Harry Bhadeshia, Prof Charles Siyasiya, Prof Pieter Pistorius and Dr Johan Westraad

    Next-generation bainitic steel with remarkable properties was the central theme of a colloquium hosted by the Department of Materials Science and Metallurgical Engineering at the University of Pretoria on the 4th of December 2017. Sir Harry Bhadeshia, a global leader in metallurgy and the Tata Steel Professor at Cambridge University, was the main speaker. Sir Prof Bhadeshia was on a visit to South Africa as a result of an application made by the Microscopy Society of Southern Africa and the trip was funded through a NRF instrument.

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  • Report Calls for Open Standard for 3D Applications in Mining Industry

    Image result for gmsgUser Interviews and Analysis Highlight Common Challenges

    Wednesday, November 15, 2017 – A new report released by Global Mining Standards and Guideline Group (GMSG) says a survey of more than 18 3D software applications shows the users experience significant difficulties and delays working with the software, collaborating with peers and learning multiple proprietary programs. A solution to these difficulties is an Open Mining Format (OMF) that would encompass a set of guidelines and recommended steps.

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  • Prof Selo Ndlovu on SAfm Radio

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From the President's Corner

  • A Christmas gift for the Institute

    It is the end of the year and Christmas is in sight. We have all had a busy year and thus look forward to a restful break, which we will fill with new memories with our families and friends. Above all, we all look forward to receiving that well-chosen wonderful gift from loved ones. A gift is always treasured. It

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  • Women in the mining and minerals industry

    Summer is finally here and Christmas is around the corner. I do hope that you are all enjoying the warm weather that is prevalent in Southern Africa at this time of the year and, at the same time, have started shopping for those elusive but perfect Christmas gifts for friends and families. Since taking over the reins as the President

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  • Singing the praises of our SAIMM members

    I would like to welcome you all to the new 2017/2018 term of the SAIMM. I hope you are all as excited as I am about what lies ahead. I am greatly looking forward to spending the next twelve months with you as we discuss and delve into different topics that interest us as members of this marvellous Institute. As

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Jobs

From the Journal Comments

  • The SAMREC/SAMVAL Companion Volume Conference

    This edition of the Journal features papers that were presented at the SAMREC/SAMVAL Companion Volume Conference held on 17 and 18 May 2016 and attended by some 100 people. The intention of the conference was to provide Competent Persons and Competent Valuators with the opportunity to prepare and present details of recognized standards and industry benchmarks in all aspects of

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  • The 6th Sulphur and Sulphuric Acid Conference

    The 6th biennial Sulphuric Acid Conference and Workshop was held in Cape Town between 9 and 11 May 2017. Approximately 90 delegates attended with regional representation from South Africa, Namibia, Zimbabwe, and the DRC and from further afield with delegates from Germany, the USA, UK, The Netherlands, Canada, and Denmark. Delegates representing plant operations management, technical experts, traders, transporters, and

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  • Advanced Metals Initiative (AMI)

    It is with great pleasure that we once again present the annual conference of the Advanced Metals Initiative (AMI). The AMI was established jointly by the Department of Science and Technology (DST) and the science councils, namely, Mintek, NECSA and the CSIR and has received generous funding from the DST since 2003. The principal objective of the AMI is to

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What price water?

‘The biggest waste of water in the country by far You spend half a pint and flush two gallons’ Attr. Prince Philip—Duke of Edinburgh

I am writing this comment at the end of the World Water Week but it might appear only in a later issue appropriate to this topic. I had the privilege of attending the Mine Water Symposium arranged by the Geological Society of South Africa in mid-March. It was an excellent presentation dealing predominately with the underground water from the gold mines on the Witwatersrand and the coalmines around Witbank and Middelburg.

The formation of acid mine drainage (AMD), its accumulation underground, and the environmental problem it gives rise to when pumped or when seeping to the surface, were discussed in some detail. Some excellent maps were presented of the central, western and southern Witwatersrand mining areas and those of the northern and southern coal areas. These areas span the continental divide and the AMD can drain into the Vaal catchment’s area, ultimately ending in the Vaal River leading to the Atlantic.

However, the area around Krugersdorp can drain into the ‘Cradle of Mankind’, now a Heritage Site, and into the Sterkfontein Caves with disastrous consequences. From the Northern coalfields, the polluted water could flow into the Olifants River and via the KNP into Moçambique and the Indian Ocean. From the southern section, the water flows through Mpumalanga past the KNP and through Moçambique into the Indian Ocean. The age old solution to the problem of AMD was to add lime to precipitate the toxic metals and dump the sludge on a slimes dam.

However, the treated effluent then contains quantities of calcium and magnesium sulphates with smaller quantities of sodium chloride which, although not toxic, represent a build-up of the total dissolved solids (tds,) which in the streams of the Vaal catchment area increase to an unacceptable level in the feed water to the domestic supply to Gauteng. Large quantities of the pristine Lesotho water then have to be used to dilute these impurities and flush them from the barrage area to flow down into the Atlantic.

There are many other problems such as the slimes dams leaking toxic metals into the rivers and there have been major campaigns to find a universal solution. Geohydrologists with the operating mines have been hard at work to reduce the quantities of AMD involved, with considerable success. It has been demonstrated that the gypsiferous effluents can be used for irrigation and indeed it is known that many soils can benefit from the addition of sulphates, but only time will tell whether this is a sustainable solution. At the symposium, some very relevant data was provided and plans for a cooperative effort were described. Amcoal, for example, had run a pilot plant using reverse osmosis to produce domestic quality water, which in due course will be made available to the Witbank municipality at considerable cost to these coalmines.

A concentrated brine and gypsum slurry still has to be disposed of elsewhere. Grootvlei mine has spent considerable amounts to treat 10 Ml/day of their AMD using the BioSure process, a patented biological reduction of sulphate to sulphides using sewage sludge as the organic food for the micro-organisms. However, a mixture of organic solids from the sewage mixed with calcium and magnesium sulphides has to be disposed of on a waste dump.

The symposium which, as a supplement to the Water Week, pointed to the urgent need to look at the water resources of Southern Africa on a holistic basis. All the stakeholders are very conscious of the need for positive action to make use of this AMD to provide sustainable solutions in line with recent thinking on future targets and challenges regarding water supplies. These are:  The undertaking by Government to supply as a constitutional right all the population with domestic water.  The critically urgent requirement to expand electric power production dramatically and in the next decade this means coal-fired stations with increased demand for cooling water.  

Increasing demands from our neighbours who are dependent on flow of adequate water from the rivers into their territories from sources in South Africa.  The use of water in agricultural irrigation is unquestionably another national priority in terms of development of rural areas and in job creation.  The announced intention of the production of bio fuels, which implies an increase in agriculture and demand for water.  There are many who believe that availability of water is a limiting factor in achieving the targets for economic development. The question of how we solve these problems will be debated by many experts. It is my conviction that an unrecognized top priority in water R&D is the conversion of sewage effluent into quality agricultural water for high efficiency small lot farming.

There are many worthwhile avenues to explore. Some aspects I believe relevant to the mining industry might be of interest. To explain them I propose water usage must be assigned a ‘net potential added value, (PAV). And the following fundamentals must apply:  No water is to be uselessly discarded into the ocean or needlessly evaporated if it has the potential of an alternative use with a positive PAV. This does not mean, for example, that the use of water to provide evaporative cooling for power stations is banned as having a zero PAV. It can be assigned a positive PAV, since the alternative is to produce more high purity boiler feed water at a cost or maybe to install an energy consuming refrigeration cooling unit.

The cost of each of these options can easily be evaluated and the lowest of these can be translated into a PAV and assigned a priority rating.  There must be a major effort devoted to assessing our water resources and alternative supplies and costs. The hydrogeologist and climatologist must play a dominant role. For example, there are countless dolomite caverns filled with water and those adjacent to mines are emptied by pumping (a negative PAV) and thrown away. They may or may not be refilled by flood water at high rainfall periods and they may have a positive PAV.  Since every drop of water in SA belongs to the state by law, it is not unreasonable for the state to assign a priority level on the basis of PAVs for any proposed usage.

These over-simplified ground rules imply a large amount of investigation and calculation and a high level of wisdom in strategic planning. But I do believe some unexpected conclusions may be forthcoming. An example may illustrate the concept more clearly. Assume a farmer can grow 3 t/ha of maize worth R3 000 with 360 mm rainfall over 6 months. Assume that with an additional 180 mm centre-pivot irrigation, i.e. 1800 m3 he can grow 6.6 t/ha. The PAV for this irrigation is R2/m3.

This is about the same as for domestic usage! It also suggests that this figure is what one could afford to pay to treat waste domestic effluent (zero PAV) to provide irrigation water. If drip irrigation were to be used at six times the water efficiency of centre pivot systems, a PAV of R12/m3 is indicated. Interestingly, the farming company Tavland using dolomitic water pumped from Western Areas Mine were achieving higher PAV values using drip irrigation on land within the mine property. There are, I believe, many similar opportunities to be explored and particularly in relation to long-term sustainability.  R.E. Robinson May 2006