Careful water management is required at openpit mines, says consultancy

Independent consulting engineers and scientists SRK Consulting SA has completed several surface water studies for openpit feasibility studies in the Democratic Republic of Congo (DRC) and tropical areas to the north of the DRC. 

One of the main issues around openpit mining in these areas is that the rainfall within a five-month period is at least twice the amount experienced in South Africa. “This heavy rainfall period is followed by a dry period where little rain is experienced,” says SRK principal scientist and hydrologist Peter Shepherd.

He explains that, during the summer months, there is an excess of water at mines, which will need to be managed in a sustainable manner. “During the winter months, it is possible that there will be a shortfall of water and water supply will need to be obtained from both local ground and surface resources,” says Shepherd.

He explains that some of the challenges posed by excess water in mines include excess water rising to the surface of openpit mines, which flows off into surrounding water sources.

Part of the feasibility studies require SRK to establish whether the mine’s operations would affect a nearby river, which supplies good quality water to the surrounding areas.

Shepherd says that, from an openpit perspective, it is important for the pit not to protrude into a river. If opencast operations affect a river, controls are needed to divert the river around the pit in a sustainable way.

“If a mining company develops an openpit through a river, they should remember that the river will not be reinstated after mining has ceased. It is therefore important that the erosion measures and diversion works are sustainable and operate in an environmentally sustainable way. 

“SRK has been investigating how to increase the amount of ore without the surrounding environment being  impacted on negatively,” he says.

Another issue that will need to be addressed is that any runoff from the sides of the pit area and associated waste rock dumps will be silt-laden, and large amounts of sediment will flow towards the river, which could eventually pollute the surrounding environment.

He explains that it is more difficult to deal with water-related issues at openpit mines after the mine is in operation, which is why SRK Consulting is striving to plan for and implement water systems and a water treatment facility before an openpit mine is in operation.

Shepherd notes that the establishment of a water treatment facility for all mining operations in a particular area is one way to alleviate potential contamination.

DRC-Based Operations
Katanga, in the south-east of the DRC, is known to be one of the richest copper and cobalt regions in the world. “However, a significant share of the copper and cobalt in this area is mined informally and exported illicitly from this African nation,” says SRK.

The company’s DRC footprint has involved delineating and evaluating the drilling of several copper and copper/cobalt deposits in Katanga.

Shepherd notes that the DRC and Zambia are playing a major role in the production of copper, and that SRK  therefore plans to be at the forefront of developments in this region.

Meanwhile, Shepherd tells Mining Weekly that the bulk of the world’s minerals are mined from openpit mines. “In a business where profit margins depend on cyclical metal prices, it is vital to run an efficient operation based on carefully calculated mine design and scheduling,” he says.

Services Portfolio
SRK Consulting SA's services provision includes scoping work, prefeasibility and feasibility studies, reviews of mining methods and technical audits, reviews and improvements of reserves, development of mine designs and schedules, mine audits, operational audits and guidance for implementing improvements, due diligence work, competent-person reports, project reviews and stock market listing reports.

The firm typically reviews an existing mine and suggests ways to extend its life through cutbacks and design improvements, taking into account changing commodity prices or revised geotechnical parameters.

It also assists mines in improving operational productivity through several initiatives, ranging from managing operational issues, such as maintenance and cycle times, to technical issues like blast design and sequential mining.

SRK has a well-established team of professionals, with unparalleled combined experience, comprising geotechnical engineers, engineering geologists and structural geologists.

The SRK team has extensive hands-on experience, gained at mines worldwide, including deep and opencast mines, from Africa to South America. 

The company draws on its skills to ensure that its solutions and advice are practical and workable, taking into account the appropriate geotechnical and environmental considerations.