Heart of iron
Iron ore production has become gradually more important to Assmang (abbreviated from Associated Manganese Mines of South Africa). Founded in 1935, until comparatively recently it specialised in manganese extraction; today it has three operating divisions based on chrome, manganese and iron ore, the last of which is being dramatically extended, as John OÔÇÖHanlon learned.
AssmangÔÇÖs principal iron ore mine at Beeshoek in the Northern Cape, about 100 miles north-west of Kimberley, started life as a manganese asset, according to Willem Grobbelaar, AssmangÔÇÖs divisional manager of Iron Ore Operations. Grobbelaar has spent many of his 30 years with Assmang at Beeshoek, and it was always known that there was iron ore there, he says. ÔÇ£It was in the early 1950s that Assmang made the decision to develop iron ore mining at Beeshoek and export it. The operation started at a low level, around a million tonnes annually, but it has been expanded over the years and in 2008 we shipped 6.7 million tonnes.ÔÇØ
These levels place Assmang, which is jointly owned by African Rainbow Minerals and Assore, as a medium sized player in the global market, behind the really big mining companies like BHP Billiton. Nevertheless, it is an important player and the second largest iron ore producer in South Africa. The domestic market takes only a small proportion of its output; 40 per cent of what it exports annually through the port of Saldanha is shipped to China, with Korea, Japan and Europe sharing the remainder. Slowing consumer demand and large stockpiles have reportedly caused a slump in ChinaÔÇÖs steel industry, and that may have affected the large bulk mining companies, but they are still importing high-quality ore, says Grobbelaar. ÔÇ£We have not seen any reduction in volumes whatsoever, although there has been an impact on price. I am confident that we are going to be able to continue selling our ore.ÔÇØ
The problem then is not a marketing one, but rather, one of production. The Beeshoek iron ore mine is reaching the end of its economic life and will not be able to sustain its current production level of six million tonnes per year, so three years ago Assmang decided to develop another property it held, some 60 miles to the  north of Beeshoek. This consists of three former farms known as Bruce, King and Mokaning, to which a further parcel of land, Parsons, was added to accommodate the crushing, screening and stockpiling operations.
The Bruce property shares a boundary with a competing companyÔÇÖs operationsÔÇöthe Sishen mine owned by Kumba MiningÔÇöso a complex agreement needed to be reached to avoid conflict and to enable both parties to exploit the boundary pillar. But developing these assets made every kind of sense, says Grobbelaar. ÔÇ£The ore at Khumani is close to the surface, and it is a very high grade deposit, with a stripping ratio of 1.7 to 1.ÔÇØ This means 10 units of iron ore for every 17 units of material excavated, and the iron ore, a high proportion of which is described as ÔÇÿlumpyÔÇÖ, in turn yields 66 per cent iron. The Khumani resources are amongst the best iron ore resources in South Africa in terms of quality and quantityÔÇöitÔÇÖs estimated that the reserves will keep the mine going for more than 25 years at an annual extraction rate of 16 million tonnes.
The R6 billion development came into production in 2006 and is now producing 10 million tonnes of ore annually. It was conceived as a greenfield development but Grobbelaar points out that, undeveloped as it was, it had the advantage of having the most important infrastructure already in place. It is close to the 860-kilometre Sishen-Saldanha railway line that runs to the port of Saldanha Bay on South AfricaÔÇÖs West Coast, from where the iron ore is currently exported. That takes care of transportation; the other thing needed for an operation like this is a reliable water supply, which can be a problem in such regions. The development has access to water piped from the Vaal River under the Vaal Gamagara water scheme, so that base is covered too.
But the Vaal is under stress, says Grobbelaar. ÔÇ£The water management system is part of the state-of-the-art design of this plant. We needed to optimise the available water, so rather than flushing used water into a sludge dam for evaporation we implemented a paste deposition system. This recovers the maximum amount of water from the ore washing process and thickens itÔÇömore than 85 percent of that we can re-use.ÔÇØ
Further leading edge techniques can be found in the beneficiation process that was implemented, he continues. This is a technical term for adding value at the mining stage rather than downstream, and in this case it is a development from the jigging process put in experimentally at Beeshoek in 2001, he explains. ÔÇ£The contaminated material is crushed then transported into a water system generating wave pulses that gradually separate the heavier ore from the lighter waste material.ÔÇØ The Batac jig system was new to South Africa when it was installed at Beeshoek by Humboldt Wedag; now proven in the field, it is recognised as a highly effective way of optimising mineral recovery from mixed ore.
On 12 August this year, on the same day it confirmed that Khumani had been commissioned on time and on budget, the directors approved additional capital expenditure of R5.5 billion for the completion of the Khumani Expansion Project (KEP), to increase the mineÔÇÖs capacity from 10 million tonnes to 16 million tonnes per annum. Now the plant is being almost doubled in size, and with the groundwork stage complete, the project is already ahead of schedule and beating its budget, thanks to project managers DRA Mineral Projects.
The extension will see a second primary and secondary crushers, screening systems and stockpile locations on the King property. In many respects, the new plant will simply mirror the existing one. To cope with the expansion, Transnet, which operates the dedicated rail line, has agreed to raise AssmangÔÇÖs allocation from 10 million to 14 million tonnes a year.
The rail operation is already remarkable enough. Every day of the year, a 342-wagon train leaves for Saldanha, with each wagon carrying 100 tonnes of ore. When the line was built back in 1976, it had an annual capacity of 18 million tonnes, says Grobbelaar. Today, it can carry 40 million, and by 2012 will be able to transport 60 million tonnes a year. Meanwhile, the port facilities at Saldanha are being similarly prepared, so by the time the downturn is over and the worldÔÇÖs steelmakers again struggle to meet demand, Assmang will be there to supply them with a better quality of ore than they can find anywhere in the world.
