Dewatering: A Vital Part of Minerals Mining

The process of extracting ore and turning it into valuable commodities inevitably puts equipment under significant wear and tear. While equipment used in the dewatering process may not be expected to withstand the same levels of abrasion as, for example, a cone crusher or a mill discharge pump, it is nonetheless important that it is both fit for the application and well-maintained to avoid breakdowns.

A bespoke dewatering plan using the correctly specified equipment can lay the foundations for many years of successful mining and avoid potentially costly interruptions to the process.

Weir Minerals can provide a total solution package, working with mine operators to understand each site’s dewatering needs, and to assess all of the specific requirements of a mine site.

It is essential to understand the operating depths and existing or new piping systems as well as the depth of the water table, the permeability of the ground and the amount of surface water that may be present.

The location and flow requirements of the pump system must be mapped out, and water inflow rates calculated before a suitable dewatering system can be designed. This must be created with a capability that exceeds the maximum requirements predicted to account for unforeseen circumstances such as a long period of intense rainfall and resultant flooding.

In fact, weather conditions can have a huge impact on dewatering systems with melting ice or unusually heavy rainfall affecting the amount of water entering a mine, especially at open pit sites.

Adaptability is vital as conditions can vary a great deal during the operating lifespan of a mine. When a new mine is excavated, work might take place just a few metres below ground level, but this can develop to significant depths of hundreds of metres.

The goal is to achieve a system capable of handling every potential challenge with reliability and efficiency.

Technology has helped greatly with this, with the advent of sophisticated control equipment such as programmable logic controllers, variable speed drives and mechatronics systems to monitor and maintain equipment function – from flow rates and pressure to bearing monitoring – which optimises productivity and safety.

Case study: 20 years of efficiency

One example of how a bespoke dewatering plan, using the right equipment, can provide a framework for years of successful mining is the solution Weir Minerals Europe put together for Severočeské doly, the largest brown coal producer in the Czech Republic.

Excavating around 23 million tonnes of coal a year, the company works two separate mines in the North Bohemian brown-coal basin, Tušimice and Bílina. The Bílina Mine produces low-sulphur coal for power generation, while the Doly Nástup Tušimice operation – the Czech Republic’s biggest open cast mine – produces coal for power generation.

Poor performance at the Nástup mine was causing problems. A lack of automation resulted in the site using manually operated pump stations and locally-manufactured pumps which proved to be unsuitable for the dewatering process. The pumps had no resistance to abrasion or corrosion, which resulted in a high turnover of equipment and spare parts, and consequently high operating costs.

Seeking a fully automated, reliable and efficient dewatering system, the operators turned to the Weir Minerals team, which was tasked with designing and implementing a full pump network.

Working with Czech and Slovak engineers, the Weir Minerals team installed a system of 127 Warman® pumps, with the aim of increasing equipment lifespan, improving reliability and reducing maintenance and operating costs.

The pumps were installed in 1992 and operated for an impressive 20 years without any wet-end parts replacement. The only parts they required over two decades were bearing assembly parts and spare elements for mechanical seals.

This compared extremely favourably with the previous pumps, which had an average wear life of just 700 hours, achieving a substantial reduction in total cost ownership while significantly improving reliability.

Products used included floating, stationary, vertical and mobile pump units, all from the Warman® pump range.

Jan Hlavacek, head of Nástup Tušimice’s (DNT) Mine Dewatering (MDW) Section, said: “Warman pumps are instrumental in the reliability of the mine dewatering system. The pumps’ sophisticated, robust design, high MPS and resistance are factors lowering the level of required maintenance. Pump design and performance allow parallel and serial pump connections that help in high geodetical head and long mine dewatering lines applications. Warman pumps facilitated fulfilling the conception – a fully automated, modern, easily operated, adaptable and highly reliable Nástup Tušimice mine dewatering system.”

A total solution

Technical innovations enable providers such as Weir Minerals to offer a full solution, not just a small selection of individual pumps. While one size certainly does not fit all, engineering expertise and experience means it is possible to provide a total service – including service and maintenance.