The Lumwana Mining is a large copper mine located in north-west Zambia in North-Western Province. Apart from copper, Lumwana copper mines also contain uranium deposits as well as other minerals. The mine is said to have reserves of up to 37 years. Moving the material involves a lot of specialized machinery, vehicles and support equipment, and a highly motivated workforce. There are six 550-tonne shovels and a fleet of 30 massive trucks, each capable of carrying a load of 234 tonnes.
Lumwana produced 271 million pounds of copper in 2016, at a cost of sales of $1.16 per pound, and all-in sustaining costs of $1.97 per pound.1 Proven and probable copper reserves as of December 31, 2016, were 2.68 billion pounds2 (207.6 million tonnes, grading 0.586%). Production in 2017 is anticipated to be 250-275 million pounds, at a cost of sales of $1.20-$1.40 per pound, and all-in sustaining costs of $2.10-$2.30 per pound.
The mine is a multi-pit, multi staged operation mining approximately 100MT of ore and waste per annum and producing copper concentrates containing an average of 120,000 tonnes of copper metal per year over a twenty (20) year mine life, making Lumwana the largest single open cut copper mine in Africa.
Production involves the use of four hydraulic face shovels for waste and ore and two hydraulic excavators (26m³) plus a smaller unit (15m³) for selective ore mining and 26 large AC-drive haul units (242t). These units are being supported by a fleet of drills, front-end loaders, bulldozers, graders and other ancillary equipment.
Metallurgical test work indicates greater than 95% recovery of copper by conventional flotation processing. Test work showed that Malundwe will produce a concentrate grading 41%–45% copper and Chimiwungo is expected to produce a concentrate grading 28%–32% copper. Sulphide ore is processed on-site by conventional flotation to produce copper concentrates for shipment to off-site smelters. Concentrates are smelted and refined into metal at smelters. The copper concentrates produced during the fourth quarter of 2010 were delivered to the Chambishi Copper Smelter and the Konkola Copper Mines Smelter at Nchanga on the Zambian Copperbelt.
Trucks from the mine tip directly into a 400t capacity ROM dump hopper. A primary gyratory crusher crushes the ROM ore from a nominal top size of 1,500mm to less than 200mm. Oversize material is deposited on the ROM pad to be further broken by a mobile rock breaker. Ore is reclaimed through apron feeders onto a conveyor belt providing direct feed, at a rate of about 2,500t/h, into the 38ft × 18ft SAG mill. The SAG mill trommel undersize discharges into a hopper and is pumped to conventional hydrocyclones, operating in closed circuit with a 26ft × 40ft ball mill. The hydrocyclone overflow (P80 of 280µm) reports to flotation, while the underflow returns to the ball mill. The flotation plant consists of two parallel trains of rougher/scavenger cells. The rougher/scavenger concentrate reports to the regrind circuit to further liberate the copper minerals.
After regrinding, the concentrate is cleaned in a conventional cleaner/recleaner circuit to reach final concentrate grade. The concentrate is dewatered in a circuit consisting of high-rate thickening followed by pressure filtration to produce a filter cake suitable for transportation. Flotation tailings are thickened and pumped to the tailings dam. Most of the plant water is recovered and recycled from the thickener overflows and tailings dam return water. Fresh make-up water is supplied from a river-water dam as required.
Lumwana Mining use consumables and reagents in the extraction of copper from the ores they mine. Key consumables include fuels, explosives, sodium cyanide, nitric and sulfuric acids, sodium hydroxide, and lime, among others. Their key process materials are consumed in their mining and processing applications; therefore, they buy them new and are not able to recycle them.
Lumwana Mining commitment to responsible mining is supported by a robust governance framework, setting out the company's expectations of employees, suppliers, and contractors in the conduct of their daily work. Lumwana Mining aim to cultivate a high-performance culture defined by the following principles: a deep commitment to partnership, consistent execution, operational excellence, disciplined capital allocation, and continual self-improvement.
Lumwana Mining engineering solutions provide its clients with a range of solutions that fit within the different stages of the project lifecycle. Lumwana Mining expertise in engineering and design helps clients meet their development, production, efficiency and environmental targets.
Every mine has a finite operational life, and the eventual closure of a mine can contribute to significant social, economic, and environmental changes, especially in nearby communities. The company believe that properly closing a mine has to involve managing and addressing its partners' social and economic concerns, as well as the environmental impacts and obligations created by Barrick. They start planning for mine closure even before construction begins.
Lumwana Mining have developed a Mine Closure Management System (MCMS) and integrate this planning into their decision making by embedding closure considerations into both their community relations and environmental management systems.