If the mine uses pumping equipment, reliability and efficiency are equally important to overall productivity. From dewatering to mud and tailings pumping to processing of produced water, the pump package operated by the mine helps to get the job done without downtime or expensive overhead. So, how can mine owners and operators ensure that the pump set they choose helps to complete the job efficiently? This is where the total cost of ownership (TCO) comes into play. TCO goes beyond the initial purchase price of a piece of equipment, but focuses on the entire life cycle cost of owning, maintaining, and operating it. Although more and more industries are turning to electricity, in terms of the transformation of mining applications, TCO plays an important role in making the best choice for application needs.    

In addition to the initial purchase cost of purchasing and transporting pump sets, TCO calculations for electric and diesel driven pump sets in mining applications may include some fixed costs, such as:

The cost of service per hour multiplied by the number of service hours per year.

For electric pump units, multiply the local cost per kilowatt hour by the number of operating hours per day multiplied by the number of days the pump runs per year multiplied by the number of kilowatts absorbed by the pump at the operating point.

For diesel-driven pump sets, calculate the cost per gallon of diesel fuel multiplied by the number of gallons burned per day multiplied by the number of days the pump runs per year.

Multiply the annual downtime by the cost of downtime. Multiply the above-mentioned annual cost by the service life of the pump and add the initial purchase cost to calculate the TCO of the pump package.

However, it is important to consider that, depending on application requirements and other factors, not all costs are weighted the same. Maintenance and repairs may result in additional loss of revenue and are a greater factor in certain operations. What kind of cost ripple effect does downtime mean to the site? It is important to consider some of the benefits that electric pump sets may bring to the mining site and how these benefits affect TCO.

First consider the installation location and use of the pump package. The most common mining applications include:

Then consider why electric packaging makes sense in every application. Questions to consider include:

Electric pumps come in a variety of sizes and configurations, and this versatility is critical to the changing needs of mines. For example, portable electric pump sets are usually paired with variable frequency drives (VFD) so that users can use one pump to handle multiple applications by simply adjusting the speed. For mining applications with different operating points, as long as electricity is available, the electric drive package can meet the specific efficiency and performance requirements of each application or be used for multiple applications. The pump can run for a day to dehydrate a small pit and then move it to a larger pit the next day without affecting the long-term performance of the motor.

Electric pumps also provide end-to-end performance. The electric pump set can cover multiple working points. In the electric drive package, when the VFD is connected to the power source, it converts the input frequency to the required output frequency, thereby changing the speed of the motor. This enables the pump to reach the performance curve range of the entire pump end.

Versatility also affects TCO. Consider the changing mine landscape over the years-it can become larger or deeper, and requires more dehydration needs. For many years, a multifunctional pump package can be used throughout the site, or it can be expanded as needed. This saves cost of ownership and operating costs.

Mining areas are usually small, with limited space for large pumps and limited space for smoke extraction. In addition, the world is changing in terms of environmental regulations, and pump operators need more options to operate cleanly and efficiently. This is where the electric pump set becomes more practical and long-term responsible. As regulations become stricter, electric packaging can become an environmentally friendly option for mining applications.

Spontaneous combustion caused by non-exhaust emissions and fuel spills in diesel engines may be a safety and environmental issue in mines. Electric motors eliminate emissions and mitigate hazardous waste cleanup caused by leaks and other Environmental Protection Agency (EPA) regulations. These environmental benefits also bring financial benefits, because cleaner operating equipment can minimize the cost of dealing with emissions issues.

The electric pump set is designed for more "no intervention" operation, which reduces the overall cost of daily wear and tear and reduces the chance of human error. There is no need to check the oil or fuel level, and there is no need to change filters or oil. The lack of fuel also means that there are no fuel trucks on site that could cause damage to the landscape.

The motor has fewer moving parts, so overall maintenance is less. The electric motor can provide remote control function, in order to realize completely without manual operation. These remote operation functions can also help protect the pump system without the need for continuous personal monitoring. The float switch can be set to automatically turn the pump on and off according to the water level, ensuring coverage when needed and preventing the pump from running dry.

Once the fixed costs and operating variables are determined, the TCO can be accurately calculated. The following are two hypothetical examples of pump set applications that may exist in mining operations:

In this application case, the pumps were used for short periods of time in different locations in the mine, where electricity was not available. For example, the pump is used to dehydrate one pit for 4 weeks, then move to another pit the next month, and so on, for a year or more at a time. Since this use case involves many short-term applications, the total energy cost of using electric motors or diesel engines to power high-head pumps only differs by a few thousand dollars.

However, in this example, the diesel unit performed well because of the lack of power supply on site. The investment required to install electricity is not worth the effort at all; it will require site surveys, additional time, and additional staff. In addition, new electrical equipment may cause high-voltage cables to pass through the site, thereby increasing safety issues. Bottom line: Diesel provides a better TCO for this type of installation.

This application looks at the TCO of the pump system of the mine processing plant. Usually, the processing plant is already electrically driven, which means that the pump set may have electricity available. The operating point of these types of applications is usually fixed; it is usually a fixed job and will not be relocated during its entire service life, which can cover many years of use. Choosing the same pump end to meet the application needs, but using electric motors and diesel engines to power them will have different total energy costs—more than twice the total energy costs.

When electric pumps are used in stationary applications, if VFD is not required, the initial investment cost is lower than that of diesel pump sets. In this case, the initial capital investment in the electrical package will save operating expenses during the entire ownership period. 

Andy Heltborg is the product manager of Pioneer Pump, a brand under Franklin Electric. You can contact him at andy.heltborg@pioneerpump.com.

Toby Wilson is a product expert at Pioneer Pump. You can contact him at toby.wilson@pioneerpump.co.uk. For more information, please visit the Pioneer Pump website or franklin-electric.com.