Chemical Technology April 2016

Are small operations sustainable? by Carl Schonborn Pr Eng

The intention of this article is not to produce a complete case study of the pumping of gravel, but to interest the reader in the sources of information and give examples of the procedures to be used when specifying pumping systems.

T elevision viewing can be a relaxing pastime and recommended for engineers and others who lead a stressful existence in this technologically-driven era of deadlines, professional responsibilities and tight budgets. One is inclined to ask what kind of programme engineers would prefer. Two great series on satellite TV [1] at the time of writing are those about small mining operations, such as ‘Gold Rush’ and ‘Diamond River Hunters’, the former based in the Klondike in Alaska and the latter in the Lesotho Highlands adjacent to South Africa. The stress and strain of sustaining these operations is palpable; the individuals who drive them can only be described as ‘men of steel’ for whom one only wishes success. They live an almost ‘hand- to-mouth’ existence with team-members who simply have to be supportive, as the alternative would be a failed venture. One could ask “What do these ventures have in common?” The answer would incorporate the following points: • Limited budgets and capital; • A minimum of on-site spare parts for vehicles and equipment;

• Skilled hands-on operators (an absolute essential); • Utmost faith in the success of their venture; • Limited or no professional or engineering assistance or expertise; and • Experienced entrepreneurs leading operations. A case in point For example, the diamond venture in the Lesotho Highlands highlights the unit operations which consist of washing of the river banks, divers manually moving the suction hoses which dredge the gravel, centrifugal slurry pumps adjacent to the muddy pools, the sluicing of the extracted gravel through a ‘trommel’, the recovery of bags of diamondiferous material and lastly, hand sorting. This may all sound straightforward and simple. The con- cession is sound, as it is based in the rivers flowing from the successful Letseng Diamond Mine (the highest diamond mine in the world at 3 000mabove sea level) which produces magnificent diamonds. One of the problems, however, is the effect the mine’s

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Chemical Technology • April 2016