Diamonds And Dust: 6 –Oranjemund
…The only access to the town was via the bridge over the river, and when leaving everyone was x-rayed to check for diamonds. So we would all have to go through a security checkpoint and get x-rayed before going on leave or out for a weekend. Due to the health implications of x-rays, employees were only allowed out once a month….
Malcolm Bertoni introduces us to Orangjemund, the diamond town where he once worked.
To read earlier chapters of Malcolm’s unusual and absorbing autobiography please click on Diamonds And Dust in the menu on this page.
Oranjemund itself then had a population of about 7 to 8,000 of which about 5,000 were Ovambo labourers working on the mine, most on a 12 months contract.
The town had everything you would expect in a place of this size. It had a school, bank, post office, police station, two pubs, supermarket, sports centre, hospital, bakery, swimming pool and so on. It also had sports fields for cricket, rugby and soccer. It even had a golf course with real grass and a sailing club.
It was clean and neat and with well-maintained parks and lawns. There was almost zero crime and little unruly behaviour. Fully furnished housing for married employees was provided free, as was electricity and water. The company even grew its own food along the Orange River and at that time had its own power station.
So the cost of living was very low and the lifestyle very comfortable. It was a great place to work for a few years to earn lots of money quickly. Many people came to work for one or two years and ended up staying 20.
Oranjemund was a closed town, meaning that it was a restricted area and visitors could only be invited by people that they knew in the town and admission was very controlled. As well, only employees of the company or contractors could stay in the town or the area.
The only access to the town was via the bridge over the river, and when leaving everyone was x-rayed to check for diamonds. So we would all have to go through a security checkpoint and get x-rayed before going on leave or out for a weekend. Due to the health implications of x-rays, employees were only allowed out once a month.
Visitors were often startled by herds of gemsbok wandering through the town, munching on the lawns and any shrubs that took their fancy. They seemed to get quite tame even though they often took a disliking to motor vehicles and often charged them just to show who was boss.
The mine was divided into five areas - Area G, Uubvlei, Mittag, Kerbehuk, and Affenrucken in that order from south to north.
The Orange River forms a geographic dividing-line between South Africa and Namibia. For millions of years, the river carried eroded diamondiferous kimberlite material from its sources in central South Africa and Botswana. This diamond-bearing material was deposited on river banks as it travelled towards the Atlantic Ocean and was deposited in beach terrace sediments and also redistributed by ocean currents to marine deposits on the sea floor. As the sea-level receded, these diamond-bearing sediments were exposed and eventually covered by blowing sand. This sand is called overburden and has to be excavated to get down to the diamond-bearing bedrock.
The Orange River left a huge amount of diamondiferous material in a huge drainage basin stretching 250 kms north and south from the estuary.
When I was there, there were two big processing plants for separating the diamonds from the ore, No 1 and No 4 plants distributed along the coast. Illogically, No 4 plant was the closest to town and No 1 plant the furthest. Two more treatment plants were built in the late 70s – No 2 and No 3. There were also screening plants that washed and cleaned the diamondiferous gravels before sending it to the process plants. These were all phased out by the mid 70s and all the ore was then sent directly to the four main process plants.
Seawater was used for all the mining and processing activities such as washing and cleaning of the ore.
The process plants usually consisted of five sections. I have described the set-up at No 1 plant.
The primary crusher section – called the A1 section:
The mined material went through a primary crusher that reduced it from a size of about a square metre to a maximum size of about 150 mm. From here the crushed ore went to a big stockpile.
The secondary crusher section – called the A2 section:
The ore was then conveyed from the primary stockpile to the secondary crusher section where the ore was reduced to approximately 50 mm. The ore was also scrubbed and cleaned here.
The milling section – called the A3 section:
Here the ore was reduced to approximately 25 mm and washed and cleaned and sent to the Heavy Media Separation stockpile.
The Heavy Media Separation section – called the A4 section:
This was the final section where the ore was processed in a cyclonic separation plant. The heavy media consisted of ferrosilicon powder mixed with water used to separate the ore from the diamonds. The heavy minerals, hopefully including the diamonds, sink to provide a concentrate which is then sent to the recovery plant. So the end result was that thousands of tonnes of ore would produce a few hundred kilograms of concentrate.
The Recovery plant – this section was not at No 1 plant as all the concentrate was sent to No 4 plant in a sealed truck for the final diamond recovery.
Since diamonds fluoresce when exposed to x-rays, x-ray sorters are used to separate the diamonds from the final concentrate. Sensors detect the light reflected from diamonds and a jet of air blows the diamonds into a collection box where they are cleaned, washed and weighed.
No 1 plant was probably spread out over at least a square kilometer, perhaps more – it was a big place.
What was unique about the diggings was that 90 percent of the diamonds were of gem quality, making it the world’s largest resource of gem quality diamonds.
