Good things come to those who wait, but a little ingenuity goes a long way as well.
Such is the philosophy adopted by
But success has its price, which in Zambia is patience. In 1992, after three decades of state control, the country began privatizing its industrial sectors to regain investor confidence at home and abroad. Key to this effort were the mining operations in the copper belt, which had been faltering since the state took complete control in 1975.
However, the process was anything but expedient, and negotiations came to a standstill in early 1998, when Zambia demanded too much for its crown jewels — the Nkana and Nchanga mine and metallurgical complexes. The operations, which account for most of the country’s output, were to have been sold as a single unit to the so-called Kafue consortium, of which Avmin was a member, only to be sold off separately to other members earlier this year.
“Although the bid fell away, we were quite aware of other opportunities on the copper belt and managed to put together what we believe to be a very attractive package,” said Ed Munnik, chief operating officer of Chambishi Metals, the unit through which Avmin operates the project.
The deal, inked in September 1998, saw Avmin pay US$50 million for a 90% interest in the Chambishi refinery and acid plant, leaving state-controlled Zambia Consolidated Copper Mines (ZCCM) with 10%. Added to this were 20 million tons of slag at Nkana, in nearby Kitwe, averaging 0.76% cobalt and 1.2% copper. For this, the company has had to commit US$100 million to build a new wing capable of processing the material.
But slag is not ore, so a creative approach was needed to win its metals. At Chambishi, this will be accomplished first by roasting crushed feed in a coal-lime mixture and then leaching the cobalt-copper alloy created in pressurized acid to produce a liquor suitable for conventional purification and electrochemical recovery methods in the existing refinery.
“A lot of people ask whether the pressure-leach will work,” said Munnik, “but our conditions are much less harsh than those used elsewhere. Moreover, the autoclave vessels themselves are tiny in comparison.”
Five autoclaves are being erected, each of which is about 5 metres high and 3 metres in diameter. All will run at about 230F and 6 bars of pressure — mild to say the least.
Another variation lies in the furnace itself: water-cooled copper will provide a surface on which a layer of slag can solidify and thus provide a protective barrier between the refractories lining the vessel and the extremely hot liquid slag within. Furthermore, the alloy will be siphoned through a narrow opening that will be showered by cold water to reduce it to particle sizes of less than 45 microns — a process known as “atomizing.”
At full speed, which should be reached in 2002, the new plant will churn out 4,000-4,500 tons cobalt and 3,000-5,000 tons copper annually. This requires that an average of 1,000 tons of slag be processed daily, ensuring production for several decades to come.
At the time of The Northern Miner’s visit, 75% of the site work and 90% of the entire project had been completed. This includes an 80-MW transformer, which can be upgraded to 120 MW should the company decide to install a second furnace down the road.
Although Chambishi posted a R27-million operating loss in the fiscal year ended June 30, improvements to toll-treating are now in effect, partly as a result of the privatization of Nkana and Nchanga last March. Says Munnik: “We’ve actually managed to expand cobalt production somewhat, and, as we speak, have been breaking new daily records in the tank house as a result of changes and more efficient practices.”
Chambishi has 5-year agreements with three nearby operations, namely: Nchanga, now managed under an option to
Feed shortages from ZCCM also prompted Chambishi to source out high-grade material from artisinal miners in the bordering country of the Democratic Republic of Congo. Offerings of similarly rich alloys for the new furnace materialized during the process.
So far, US$15 million has been spent upgrading the existing facility, with an additional US$20 million applied to ancillaries, such as power. Excluding the new wing, the existing one has the capacity to produce 2,500 tons cobalt and 15,000 tons copper annually.
For the 10 months ended June 30, Chambishi treated 78,012 tons of concentrates (18% of which came from the Congo) to produce 2,181 tons cobalt and 7,760 tons copper; this is in addition to Avmin’s share of production from the Nkomati nickel mine in South Africa (its only other base metal operation), where 4,398 tons nickel, 2,517 tons copper and 227 tons cobalt were produced in the year ended June 30.
Meanwhile, Munnik says the new plant should generate a 15% return on investment, assuming a long-term cobalt price of US$8 per lb. Unit capital costs are projected at US12 per lb. cobalt, with cash costs expected to be among the lowest for international producers.
A few pleasant surprises have arisen, mostly in the form of a high-grade pocket (1-3% cobalt) discovered beneath some of the older buildings at Nkana. Regional shortages also ensure a steady demand for Chambishi’s byproduct, acid.
Construction has exceeded 1.8 million man-hours without a lost-time injury — a feat shared by relatively few companies. However, 400 cases of malaria have been reported to date.
The work is providing 1,300 jobs to the impoverished region, with more than 100 jobs projected for the commercial operation.
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