Enhancing Efficiency and Safety: The Importance of Choosing the Right Mine Dewatering Pumps
Introduction
In the dynamic and challenging world of mining, ensuring efficient operations and maintaining a safe working environment are of paramount importance. Choosing the right mine dewatering pumps is essential for the smooth functioning of the mine, as well as safeguarding the workforce. In this blog post, we will delve into the various mine dewatering pumps that are available to mine asset owners.
Some key considerations include materials of construction, how pumps are to be driven, and what style of pump suits the particular application.
Materials of Construction
Selection of appropriate materials is very important. Abrasive applications will require harder materials. Corrosive applications will require stainless steel or duplex stainless-steel materials. Areas not containing abrasives and not corrosive, may only need standard materials, like cast iron.
For abrasive applications, selecting the right material will ensure longevity of the pump, but these materials can get quite expensive. High chrome or N-hard materials, although very hard and the best for wear resistance, can be many times more expensive than hardened iron parts. So, if an application does not need “super-hard” materials, capital savings can be made by selecting durable hardened iron parts with hardness levels in the order of 400 BNH.
For corrosive applications, a variety of stainless steels are available [eg Grade 304 or 316], as well as duplex and super-duplex stainless steels. Again, it is important to get material selection right. While highly corrosion resistant super-duplex materials are suitable for very corrosive applications, water that is not so aggressive can possibly be handled by pumps manufactured from SS316, or even manufactured from cast iron, with wearing parts only fabricated from corrosion resistant materials.
Pump Drivers
Pumps can be driven in a number of ways. By electric motors, diesel engines, or even hydraulic motors.
Naturally, if power is not available at the site of particular applications, the electric motor drive is not an option. Where power is available, electric motor drives are easier to maintain, do not require re-fuelling, and are quite efficient.
Where mains power is not available, combustion engine driven pumps are most widely used, with diesel being the preferred fuel. The wide size range of sizes allows for the driving of a vast range of pumps, from small 2” ones through to high head high flow dewatering pumps.
Some applications may also suit hydraulically driven pumps. Here, PTO pumps from diesel engines are used to drive hydraulic motors. These may suit pumps mounted on trucks, or where suction lift applications exceed the limitations of self-priming pumps, and where mains power may not be available.
Pump Style
The application often drives the style of pump, but there are some “cross-over areas” where the choice of the pump is down to experience, preference or availability.
Large, high-head dewatering pumps are generally large prime-assisted diesel driven units. Water sources are often away from an electrical power source, and water needs to be pumped a long way, or over high mine walls, limiting choices to these large units.
When the flow rate is lower, mining operations may have a choice between true self-priming [wet-prime] pumps, prime assisted [dry-prime] pumps and submersible pumps [if power is available].
Prime Assist [Dry-Prime] Pumps
These pumps can be driven by electric motors or diesel engines. They need an auxiliary priming system, inclusive of an air separation [priming] chamber, a non-return valve [to prevent the pump trying to pull a vacuum on the discharge side of the pump, as well as the suction], and a priming system [could be a compressor/venturi, diaphragm priming pump, or dedicated vacuum pump]. Although more versatile, with larger flow ranges and larger pressures, these pumps do require more maintenance than “true” self-priming pumps, and because they are more complicated, may not be considered as reliable as “wet-prime” pumps.
Self-priming Pumps
Also known at “true” self-priming or “wet-prime” pumps, these pumps use an integral tank within their casing to allow the impeller to turn in a “flooded” environment to create the required vacuum to prime. A much simpler pump that is easier to maintain, and more reliable. The only drawback of this technology is that they are limited in their flow range [to about 250 L/s], and their pressure [limited to about 90 metres]. They also need to be charged with water to enable priming. These pumps provide a genuine alternative where applications fall within their hydraulic range.
Submersible Pumps
Electro submersible pumps are another alternative when electrical power is available. These pumps are available with wide flow ranges, and some with high pressures. Voltages at sites vary, with 415v and 1000v being popular.
These pumps can be mounted under pumptoons, or be located in purpose built wet wells. They are also available in a wide variety of materials.
Hydraulic Submersible Pumps
When electric power is not available and the suction lift is higher than a wet or dry self-priming pump can reach, a hydraulically driven submerible pump could be the answer. These pumps have a hydraulic motor that is driven by a diesel engine power-pack.
