Paterson & Cooke is currently engaged on several tailings pumping system upgrade projects and a recent article by one of its Directors Peter Goosen deals with the question of how to plan for them. These upgrades are typically associated with increased throughput requirements (associated with a plant expansion), increased pumping head requirement, (associated with increased pumping distance to a new tailings storage facility, or increased elevation on an existing TSF).

Goosen says that a common feature on many of these projects is that the original design and layout did not make allowance for future expansion, something that is almost always required over the life of mining and mineral processing operations. “It is understandable that at the initial design and construction stages of a project, capital costs are under close scrutiny, and therefore tailings pumping system installations are typically designed and built to accommodate initial plant design capacity and nothing more. It is also typically designed to service the initial TSF site, which will likely be the closest potential site.”

P&C has noted that where the tailings pump house, or area allocated in the plant for tailings pumps, will not accommodate additional pump stages or pump trains, the load on the system is increased instead and the pumping system is “pushed” beyond design capacity. This leads to one or more of the following undesirable consequences:

• Increased wear and maintenance requirements on pumps, particularly if pump speeds have been increased to increase system throughput
• Sub-optimal access for operation and maintenance if additional pumps have been “shoehorned” into a constrained space
• Excessive spillage from the tailings tank over-topping when tailings pumping capacity cannot accommodate surges or peak plant throughput rates
• Impacts on the TSF operation such as preferential deposition at “closer” discharge points, potentially resulting in the inability to properly control pool location.

A recommendation P&C makes to anyone looking at laying out a new tailings pump installation is to give consideration to accommodating future expansion

Some suggestions are:

• Leave space for additional pumps to be added in future. This may be allowance for additional pumps on existing pump trains, and possibly space for additional pump trains
• Be generous with the spacing between pumps, so that the original pumps can be replaced with larger units in the future
• If constructing an over-sized pump station in the initial build is not viable, then provide space around the pump station for future expansion. The same considerations will apply for electrical infrastructure which can occupy a footprint as large as the pump station. Allow space for future switchgear within the switchgear room, and spare transformer bays. Or provide space for the switchgear room to be expanded as well as space for additional transformer bays.

“With all these considerations in mind, we are currently developing the layout and detailing on a tailings pump station for a key southern African client and our project team has made allowance for future expansion. The initial outfitting of the pump station is with three pump trains, each with three times 355 kW, 12/10 pumps in series. Space is provided for a future fourth pump train, and for future fourth and fifth pump stages per pump train. This will accommodate discharge to currently operating tailings dams, and a planned future TSF, all to final height.”

Particular attention has been paid to features with operations and maintenance personnel and their various activities in mind. Clear access routes are provided to all equipment within the pump station area. The pump station area is covered by a portal-frame roof structure, with a travelling gantry crane servicing all equipment. A workshop area is provided within the pump station building and is also covered by the crane. “We believe that investment in facilities to support operations and maintenance personnel and their activities will pay dividends in the form of improved availability, more effective maintenance practices and improved safety.”