Harvinder Bhabra, Global Product Manager, Dewatering at Weir Minerals, looks at the dewatering challenges facing mines around the world. In this first part of a two-part series, he covers the engineering challenges behind an effective dewatering system.

Water is the lifeblood of almost any mine.

At the outset of any project, one of the most fundamental questions that needs to be answered is how will the ground be kept dry enough throughout the lifespan of the mine to allow safe excavation and protect personnel and equipment?

At the same time, a steady supply of water needs to be maintained to keep the process running efficiently. Depending on location, having insufficient water on site can be just as problematic as having too much.

These two challenges create the complex balancing act of water management on any mine.

System design and engineering

There are many complex considerations that engineers need to bear in mind when designing a dewatering system: the depth of the water table, the porosity and permeability of the ground, the amount of surface water present, the presence of geological features such as underground water pockets or rivers and the level of local precipitation, and how this varies seasonally.

Understanding these factors and how they impact the dewatering requirements throughout any given mining project involves a lengthy and detailed modelling process, during which the positioning and flow requirements of the dewatering pump systems are mapped out.

Once the water inflow rates have been estimated from complex calculations, a dewatering system is then designed and specified with a capability that exceeds the maximum requirements that could foreseeably be presented by the project – for example, by an extended period of unusually heavy rainfall.

It’s important not to underestimate the often significant impact of weather conditions. Periods of intense rainfall or seasonal ice melt can drastically increase the influx of water, especially into open-pit mines, so it is vital that the dewatering system is able to handle the peak volumes that could reasonably be anticipated in order to prevent production delays and safety issues.

Adaptability

Throughout the lifespan of a mining project, the requirements for the dewatering system can change significantly and it’s important that these stages are properly planned. For instance, when excavating a new mine, initial work might be taking place just a few metres below ground level, but over the course of the project this level might descend to hundreds of metres deep.

A single solution is unlikely to be suitable to handle the large variations in pumping flow rates and discharge head, therefore multi-stage systems are often needed, with additional pump stations added as the mine workings progress.

The goal is to achieve a solution that is capable of coping with all of the potential dewatering challenges that it might face, but which also operates efficiently.

Technological advances have made this easier to achieve. Variable frequency drives and sophisticated programmable logic controllers (PLCs) can control pump speeds, enabling them to adapt to changing conditions.

This increase in complexity has, in turn, created a demand for remote and automated control and operation so that personnel do not have to physically be at the pump in order to make any system adjustments. Mechatronics systems are evolving at a rapid rate, using the latest technology to detect, monitor and control equipment from a variety of inputs including flow rate, pressure, bearing monitoring and vibration. Our smart, connected products provide “live” statuses of all equipment, significantly increasing operational efficiency and productivity, safely.

In the second entry of this two-part blog, we look at the challenge of specifying the right equipment for a given dewatering application.

Weir Minerals offers a wide range of pumps and equipment to cover any dewatering requirement. The animation below takes you through each application. For more information on Weir Minerals’ dewatering products, visit our dewatering page.