Engineering and construction group SNC-Lavalin has completed the fourth phase of copper/cobalt producer Katanga Mining’s Kamoto Copper Company (KCC) expansion project in the Democratic Republic of Congo (DRC). Together with the successful completion of the third phase of this project, this is the largest project SNC-Lavalin’s Johannesburg office has undertaken to date, says the company.

Phase 4 of the KCC expansion project involved upgrading the plant to produce 270 000 t/y of copper. SNC-Lavalin was awarded the contract for the front-end engineering and early works in August 2010.

The company’s integrated engineering solution was based on a model that incorporates metallurgical simulation software, namely Metsim, which integrates and optimises mass water and energy balances across the entire plant, decreasing the consumption of reagents, water and power and ensuring effective interfaces between the different elements of the plant.

“Prior to being awarded the contract to conduct front-end engineering, we carried out a scoping study which involved the examination of 12 different options to increase production at the plant. Of these, we recommended a low-cost, fast-track option and, in April 2011, we received the go-ahead to proceed with full implementation. The salient feature of this option was that it was engineered to use much of the existing plant, thereby achieving significant cost savings,” asserts SNC-Lavalin project manager John Dixon.

He further mentions that a new solvent extraction (SX) plant was also introduced at the Katanga mine.

SNC-Lavalin’s scope of work was scheduled for completion by the end of September 2013 – a requirement that was met using a flexible approach, since it was important to accommodate changes within the scope of work and services as they occurred.

A completely new flotation section was constructed within the confines of the existing building, presenting significant challenges in terms of geotechnical conditions and space constraints. Dixon says the new equipment has proved so successful that KCC is considering replacing all flotation circuits with similar equipment.

Solvent Extraction Plant Processes
When SNC-Lavalin undertook the design and procurement of the SX plant, it provided KCC’s construction crew with technical support. The plant, with a significant footprint of 800 m × 600 m, uses kerosene jet fuel to extract the copper and is fully fabricated from stainless steel to resist the aggressive and highly acidic chemicals in the circuit. Because of the kerosene, all equipment is explosionproof.

The SX plant’s 15 tanks, each 27 m × 18 m in size, were manufactured in Johannesburg and assembled on site in phases, one train at a time. Each train has a nominal capacity equivalent to the production of 100 000 t/y of copper.

“The conversion of the existing electrorefinery into an electro- winning plant proved to be a highly cost-effective initiative, necessitating the rehabilitation of 720 cells in five individual banks and the installation of completely new electrical and piping reticulation within the plant.”

Dixon adds that this was a high-value project and, because of the high grade of the copper, the company decided to proceed directly with implementation while detailed engineering progressed. The combined engineering team, comprising KCC and SNC-Lavalin personnel, took this decision on the basis of predeter- mined criteria.

Project History
KCC is a joint venture (JV) between diversified mining major GlencoreXstrata’s Katanga Mining, with a 75% share in the JV, and DRC-based State-owned Gécamines, with a 25% share.

Gécamines first began oper- ations in the Kamoto underground mine in 1969 and, by the 1980s, the mine was producing three-million tons of ore a year. Before shutting down in October 1990, it had produced 59.3-million tons of ore grading 4.21% copper and 0.37% cobalt, which are among the highest grades in the world.

“The existing plant was built and commissioned in the early 1970s and, although it was well designed and constructed, the plant has become outdated and is in poor condition,” says Dixon.

He adds that, based on findings in an earlier feasibility study, SNC-Lavalin was brought on board in 2010 to provide an integrated engineering solution to complete restoration of the plant, enabling it to reach full operational capacity as part of Phase 3 of the project.

“The company’s scope was to upgrade the plant to existing nameplate capacity, which included the rehabilitation of existing plant and equipment,” explains Dixon.

He adds that work done by SNC-Lavalin in the third phase of the project resulted in an extension of SNC-Lavalin’s contract to undertake the fourth phase of the project.

“We were able to interface effectively between the owners’ project team and their operations teams. “The design process had gone well and we ensured that there were people on the ground with the necessary expertise and skill in terms of implementing projects within an operating environment. Our achievement is that we’ve brought a dated and very large plant up to speed to the client’s satisfaction,” he says.