Pumps & Systems, March 2013
Mining applications are as diverse as construction or water and wastewater applications. Each jobsite has specific requirements and needs. Underground and open pit mines have several layout and design obstacles. Regardless of the mine and its setup, water is a mine’s biggest enemy.
Getting water out—and keeping it out—is the primary focus of any mine plan. The deeper the mine, the more water that will be encountered and need to be removed. Once dewatering begins, mine planners can get back to what they do best.
A centrifugal pump with a fuel cube
A pump company or dewatering solutions provider can partner with mine planners and engineers in the design and planning stages. A system analysis should be performed first. Then pump selection can begin. Factors to consider in mine planning include portability, easy maintenance and solids-handling.
Another consideration is pH. Pumps can be customized with durable materials of construction specifically designed for low pH and other corrosive liquids.
Pump systems are completely customizable, and the right one can only be selected after the operator or mine engineer understands the mine plan. Pump and piping design and pump control can be tailored to the mine plan. In addition to length of flow, elevation and discharge, consider layout drawings, hydraulic grade lines and pipe wall thickness. Perform friction loss calculations.
A diesel-driven centrifugal pump
Also, consider present and future requirements. A mine’s design can change based on weather conditions, landscape vulnerability and market demands. A dewatering pump company can help design the mine plan, so mine operators and engineers can focus on mining. A reliable dewatering system allows them to continue working.
The power source is another component to consider for mine dewatering pump selection. When selecting a centrifugal pump to fit their needs, many mine operators select diesel-driven centrifugal pumps. As with any other application, operators have options. The initial setup costs should be measured against the lifetime costs of pumping for the project. For a temporary job in a mine or quarry, diesel-driven pumps will typically be the most logical choice. Setup costs are virtually zero. The pumps run on diesel fuel for the short duration of the project. If available near the mine, natural gas is also an option.
Hydraulic submersible pumps are another option for mine planning. These pumps feature a power pack fitted to a submerged pump. The pump ends usually sit at varying levels of submergence, and their power packs sit above ground. They are ideal for abrasive fine sand, high specific gravity (such as that found in slurries) and can offer a total dynamic head up to 600 feet. These hydraulic submersible pumps can be diesel driven or electric, depending on system requirements.
A diesel-driven hydraulic power pack in the foreground (pumps in the background are diesel-driven booster pumps)
If a project is more long-running, consider electric-driven pumps. Electric submersible pumps have a solid history in mining applications. These pumps can handle moderately large flows (up to 2,500 gallons per minute) or extreme high heads (up to 750 feet).
In addition to these submersible pumps, electric-driven centrifugal pumps are ideal for both prolonged temporary pumping and permanent installations. Designed for long-lasting durability, these pumps were initially used in industrial and municipal applications. However, their benefits span many more applications. A permanently installed electric-driven centrifugal pump will provide reliable, continuous pumping and reduced operating and maintenance costs.
While not frequently used in mining applications, electric-driven centrifugal pumps are a viable option for a permanent installation or lengthy temporary pumping job. If the site location is not extremely remote, an electricity source can be found and power lines run to the jobsite. Accessing electricity can outweigh the lifetime costs of a diesel-driven pumping system if the timeframe is long enough. Costs for running electric-driven pumps will eventually be the more economical choice, even factoring in initial setup costs.
For temporary jobs in which refueling is difficult, an electric pump is the ideal solution. Once power lines are established, pump accessibility is almost a nonissue. Lines can be run into underground mines and bolted to the ceiling. Mine planners may not consider this option, but once designed and implemented, electric-driven pumps require less access. They do not need refueling, and their motors require less servicing. These centrifugal pumps also reduce the carbon footprint of any job.
Case Study: Electric-Driven Pumps
A gold mine had an environmental restriction that would no longer allow diesel-driven pumps, which had been operating at their site, provided by a rental company. The mine requested a solution for a portable pumping system that could use the voltage that was available at the tailings dam. The pumps needed to supply 7,500 gallons per minute (gpm) to the roaster facility (the location used to heat the ore and extract the gold) and 4,000 gpm to the autoclave system (similar to the roaster facility, but using pressure along with heat) at the mine.