Pumps and mining
As every miner and mine owner knows, there are a multitude of dangers and other challenges associated with their work, especially for those working underground.
Explosions, cave-ins, fires, and flooding are just a few of the potential dangers that can quickly turn a relatively safe working environment into a disaster, both in terms of human life and to Mother Nature herself.
Thankfully, most of today’s mining operations are well equipped to handle the most severe of situations, and one company that stands out when it comes to the safe control of water is Atlas Dewatering Corporation.
With almost 70 years in the pumping, dewatering, and environmental groundwater/surface water industry, the Concord (Toronto) based company specializes in full turn-key services to the mining industry, including pump rentals, sales, and service.
Stephan Kokeza, Northern Territory Manager for Thunder Bay / Timmins says the company specializes in pumping and dewatering systems. With specific reference to mining, Kokeza says: “One of our goals is to assist in bringing environmental liabilities under control by offering local supply, and expertise, coupled with emergency response plans for things like spring run-off or tailings dam leaks.
“The two-year-old Atlas Thunder Bay facility, with more than 60 pumps now in the rental fleet up to 18 inches, and miles of hose and pipe, has allowed us to respond to several mining emergencies this year with pumps and men on the ground the same day. And, with Godwin Pumps (Xylem) at our side, combined with our rental fleet, we are confident we can solve any challenge a mine may be facing.
“In many cases, the reality is temporary and emergency pump systems do not get full benefit from all of a mines departments or review, and the supplier must ensure that the pump systems are safe. For example, such as ensuring the piping pressure limits of the HDPE line we may tie into are not exceeded, or the customer uses proper high-pressure hoses, connections, and with whip checks. It takes a big fire-fighter to hold a two-inch diameter fire hose with 60 psi, so imagine an eight-inch diameter hose on a pump with 250 psi.; people do not see this all the time, and we are continually educating our clients.”
Kokeza adds: “Our experience in other industries with a Ministry of Environment Certified work force, working with fish-sensitive areas, permits to take water, and groundwater water treatment allow us to take a pro-active approach to prevent, detect, and avoid emergencies, and supply plans and pumping systems that will reduce liabilities.”
Atlas also offers an extensive line of WellPoint, educator, deep-well, and pressure-relief systems to accommodate any dewatering need. “If the water table needs to be lowered, after 70 years, we are confident we have done it before,” says Kokeza.
And finally, of particular interest to the mining community, the company’s pumping business offers pumps for open-pit dewatering, tailings and ponds water, and slurry management, emergency response, temporary fire pumps, temporary process pumps, and systems designed to deal with fish habitats and or treatment.
HOW COATINGS HELP
Pumps and other fluid-handling equipment may suffer from multiple problems including physical and mechanical damage, as well as general or localized erosion and corrosion. These problems are linked to decreased efficiency and poor performance, leading to increasing operational costs, so therefore, minimizing performance deterioration is an important factor for pump manufacturers and end users.
Indeed, hydraulic losses account for most of the efficiency decrease (9% for a mixed flow pump to 20% for radial flow). Coating technology can help in decreasing these losses, increasing the pump’s performance and reducing operational costs.
In pumping equipment, it is possible to reduce power consumption and improve the hydraulic properties by changing the pump surface finish.
In fact, the loss of efficiency is caused by frictional forces created between the fluid and the walls, the acceleration and the slowing down of the fluid, and the change in the fluid flow direction.
The smoother the pump walls, the more fluid turbulence will be reduced, thus reducing the energy required for the pump to move the fluid through the hydraulic passage.
In order to get the best performance possible, pump manufacturers seek to create the smoothest surface possible to reduce the turbulence of the fluid. This can be obtained by the polishing of the selected metal, such as stainless steel; however, this method is extremely time consuming and expensive.
A smooth surface finish can also be obtained by applying an erosion-corrosion resistant efficiency coating on the pump’s volute and impeller. These polymeric coatings are specifically designed to improve efficiency on fluid-handling systems and protect metals against the effects of erosion-corrosion. Their unique combination of properties such as self-leveling application, hydrophobicity and hydraulic smoothness makes these coatings ideal candidates for lining the hydraulic passages of pumps. These coatings possess a low electronic affinity towards water molecules and result in a smooth glossy finish once applied onto a metallic surface. This allows the water or other aqueous solutions to easily slide on the surface of the coating.
The smoothness of these hydrophobic epoxy coatings is evident when the surface condition of high-performance coatings designed to improve efficiency of pumps, pipes, valves and other fluid -handling equipment, was measured as 15 times smoother than polished stainless steel.
As a result of the smoother surface and reduction in flow resistance and friction, the hydraulic performance of the pump can be increased. The performance curves of a single-stage, end-suction centrifugal pump with a 250mm suction and discharge branches before and after being coated was performed by the British National Engineering Laboratories (N.E.L.) and the pump, in uncoated condition and running at 1,300 rpm, was originally found to deliver 875 m3/h at 26.5m head and with overall peak efficiency of 83.5% (overall efficiency defined as the ratio of water power output to mechanical power input at the shaft).
Testing of a coated pump gave a maximum of 6% increase in the peak efficiency and a reduction in power consumption of 5.1 kWh at duty point. Assuming a 5,000 hours operating cycle/annum, the power savings over this period would amount to 25,500 kWh.
Similarly, results have been measured by many pump manufacturers around the world, and feedback on industrial equipment protected with coatings show that it is possible to achieve a return in excess of new pump.
In 2013, a water-elevation plant in Portugal was looking for a solution to improve its hydraulic efficiency. This plant was chosen because of its high energy consumption and costs, with an annual consumption of 1.7 GWh/year and a volume of water propelled of 1.2 Mm3/year recorded in 2012.
The client was looking for a reliable and long-term solution to restore the damaged pump while reducing internal friction in the impeller and volute to enhance hydraulic efficiency.
An internal pump coating was chosen to maximize water flow and reduce energy consumption while reducing internal wear and minimize future maintenance actions.
The pump was disassembled and all internal surfaces were grit blasted to remove the previous coating. The surface was then cleaned and examined to ensure that it was free of dust and other particles.
After grit blasting, the application areas were masked for the application of an epoxy paste grade composite for metal repair. Simply applied using an applicator provided with the product, this material was used to reconstruct the areas damaged by corrosion, rebuilding the original surface profile. The solvent-free composite provides excellent corrosion resistance and helped ensure the substrate is protected when it comes in contact with an abrasive material.
Within the two-hour over-coating window, the first coat of the composite was applied by brush, followed by a second coat to obtain a total dry film thickness of 500µ. This coating was specified because it provides protection against erosion and long-term corrosion of equipment, whilst improving the efficiency of the pump.
The main results after coating the pump and changes to the programming of the water elevation plan were:
- Reduced energy consumption during non-peak hours 44.9% to 39.3% (-12.5%)
- Reduced energy consumption by 14.9% (kW / m3), 147,247 KW/h recorded in eight months 20.3% cost reduction
- ROI: 4 months of operation
Information for this Special Report provided by Belzona Polymerics Limited, U.K. , a world leader in the design and manufacture of polymer repair composites and industrial protective coatings for the repair, protection and improvement of machinery, equipment, buildings and structures.