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| Blue Streak Rocket - biggest launched from Woomera |
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| Over 6,000 rockets were launched from Woomera |
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| Beautiful views from the lower Finders Ranges |
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| Pt. Augusta where Leigh Creek coal is burned |
We were told that all spots on the Olympic Mine Tour had been taken, but if we turned up at 8:30 am, we may be lucky and get tickets from a cancellation. We were at the tourist centre bright and early, but no-one had cancelled… so we missed the mine tour. What we did enjoy was a 30 minute presentation by the mine’s public relations officer and a 10 minute video. The mine must be extra-extra profitable. The ore is so rich and so extensive, they have relied on Stope Mining techniques that reduce labour to a minimum. Currently, this is underground mining on a large scale (the biggest underground mine in Australia). It will be replaced by a (stage 2) open cut mine that defies the imagination. The size of the open-cut will be the same size as Sydney Harbour and over 1km deep. It will make the ‘big pit‘ at Kalgoolie look like a dinky-toy sandpit effort.
BHP has its environmental impact study approved by State Government and is now with Federal Government. Approval is expected in the next few months. They will then start to remove 300 metres of overburden… a task expected to take 3-years. They will build a mountain range that will tower over any neighboring hills. The wealth they will extract was not stated, but it will probably exceed by many times the current annual GDP for South Australia. BHP is loved in the town of Roxby Downs. They offer another 40 years of employment in a town that does not feel like an outback town. The streets have grass, there is no dust. The layout of the town has a great community feel (no long stretches of straight suburban streets.). BHP has a waiting list of people seeking employment at Roxby Downs (unlike the other mining towns in the outback).
The technique of Stope mining was interesting. The geologists diamond drill to identify the position and depth of a rich pocket of ore. Tunnels are dug to the base of the selected ore body and transport links are built. The selected mine area takes the shape of an upside down milk carton, with the wedge shape at the bottom being the shoot head that direct the mined ore into the transport. The transport is typically a train (automatically run - no driver). The miners blast above the shoot so that the ore falls downward into the shoot. When the train (or dump truck) turns up, gravity feed is used to move the ore into the transport. The ore is moved to one of two large mining shafts that brings massive volume of ore to the surface. The ore is then fed to a conveyor belt to move it over to the processing plants. (Most of the 2,000 staff and 2,000 contractors are employed in the processing plants.) Underground, the ore is crushed to a fine powder and above ground washed with an acid mix. Copper is the majority of the minerals and it is also the lightest. They use special xanthate reagents to make the copper sulphate hydrophobic (I copied this part from a BHP leaflet) and use a bubbling technique to bring the copper to the surface of the liquid and it overflows into giant electrolysis plants. This is where most of the electric power is used. The plant produces copper with a purity of 99.999% that is trucked out (by Linfox trucks… 93 of them each day).
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| Power is sent back to Roxby Downs - in a straight line! |
Uranium is (in part) a residue from the copper electrolysis but mainly from the ore that was not dissolved in the copper sulphate wash. There is a second acid wash that dissolves the uranium content and take the liquid away from the residue (gold and silver… some residue!) Once separated, they add an alkaline (ammonia) to the acid mix that settles the yellow cake. This is placed in 44-gallon drums and sent by road down to Spencers Gulf for export to USA, Canada or France. It takes 2-days production of uranium to produce sufficient energy to meet the needs of the mine and Roxby Down for a whole year [if it used nuclear energy!] The presentation did not expound on the extraction process for gold or silver… but being so heavy and relatively inert, I guess they separate them by centrifugal force. Greenies don’t like miners… but Roxby Downs is so clever and efficient, I think Greenies would have to feel some admiration for the achievements in extracting wealth from hostile environment with so little environmental damage.
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C J Denis lived in Laura
in the wheat belt |
After the presentation ended, we started the long drive (800 kms) towards Adelaide. We had planned to stay the last night in a small town somewhere in the south Flinders ranges (in the wheat-belt). After a solid morning’s drive, we took a few detours to enjoy the beautiful scenery of the southern Flinders range. The rainfall has been so generous this winter; the landscape was an emerald-green. Nearer sun-set, we started looking out for accommodation. The sparseness of the population was brought home by the lack of traveler’s accommodation. We thought about staying in a couple of the old pubs… but each time we chose to chance our luck with the next town to get something more comfortable. This process continued until well after dark and we ended up only 100 kms from Adelaide. It had been a long day… but we had seen some beautiful country.
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