With every mine or quarry site needing to evaluate dewatering requirements at some point, it is important to determine the exact nature of potential water problems to inform the design of a fit- for-purpose dewatering solution.
Marnus Koorts, General Manager Pump Products at Weir Minerals Africa, advises that for every dewatering project it is important that the customer works with an original equipment manufacturer (OEM) that understands the environment, site conditions and specialises in dewatering solutions.
In any mining environment, water comes from several sources, with rain being the most prolific in some regions. However, other sources such as natural seepage and aquifers can yield a significant amount of groundwater, especially in underground mining operations which can lead to considerable disruption of operations with costly consequences.
A comprehensive, reliable and flexible dewatering plan is therefore essential to remove excess water from working areas in order to allow operations to continue while safeguarding operators and maintaining productivity.
Several factors are worth considering before selecting and installing a dewatering solution, and this should start with a thorough assessment to facilitate the design and build of a fit-for-purpose dewatering solution that is site-specific, cost effective and manageable.
“Each operation’s dewatering requirements are different,” says Koorts. “Consequently, we believe that dewatering solutions should be customised to suit the site conditions. At Weir Minerals, we don’t supply a dewatering solution without first going to the site to assess the different parameters that determine an optimal solution for the operation.”
Another critical factor to consider is the head pressure required to pump the water out of the pit. Many of the pits are very deep, which means additional booster pumps are needed to overcome the large vertical lift. Based on the mine site configuration and whether an open pit or underground operation, these could be positioned at multiple levels to help raise the water.
“The characteristics of the water can have an impact on the final equipment and materials used. For example, the pH range, temperature, corrosive and abrasive content all play a critical role in selecting the equipment to transport water effectively. The presence of solids in the water, the specific gravity, size distribution and content percentage will determine the type of pumps required,” he says.
In addition, Koorts notes that there is an industry perception that dewatering is just about the pump itself. He, however, cautions that a pump is only one part of the equation with a dewatering systems comprising numerous critical components including pumps, drive units, priming systems, control systems, control valves and discharge piping.
“It is critical that the preferred dewatering system OEM be able to integrate all these various components into a single system. At Weir Minerals we have a large portfolio of in-house and external components that allow us to provide a fit-for-purpose dewatering solution and take responsibility for the entire system’s performance. These include multiple pumping solutions, drive units, pontoon barges, electrical control systems, hoses, discharge piping systems and hydrocyclone separators, amongst others,” concludes Koorts.