How to Valorize a Wet Impoundment

Large volumes of water is frequently used in minerals handling, mining & mineral processing operations, leaving contaminated solid and liquid waste behind after the mined minerals or ores are removed. Since these operations are dealing with very large quantities of water, the preferred method of decontaminating the water is to build large stabilization ponds or lagoons, pump the waste water in, let the particulates within the water settle to the bottom, remove the water from the top, dry out the leftover materials, and sift the materials to remove any minerals that may be usable. This is known as the sedimentation method of liquid waste disposal and generally deals with non-hazardous materials.

Fly ash, or residue from coal fired power plants, is often collected in such wet impoundments. Several recent and high profile releases of impounded fly ash have demonstrated the shortcomings of wet impoundments for long term storage of fly ash. This does not need to be the case – fly ash is a value added construction material – when added to concrete it improves workability, reduces water demand, improves long term strength and increases resistance to chemical attack. Equally important – fly ash that is locked into the concrete matrix has no potential to leach metals into groundwater, it is fully encapsulated. Fly ash also reduces the CO2 footprint of concrete – each ton of fly ash used displaces a ton of cement, and thus avoids one ton of CO2 that would otherwise be emitted during the cement manufacturing process.

ST Equipment & Technology (STET) offers a solution to beneficiating wet fly ash impoundments by removing the carbon (loss on ignition) content of the material from the fly ash, making it sellable into ready-mix concrete applications. By beneficiating an existing fly ash landfill, utilities benefit from taking a liability (impounded fly ash) and turning it into a value added material.

The process of beneficiating materials from impoundments or tailings ponds is not limited to fly ash. Many wet minerals processing operations, for example iron ore & phosphate rock, utilize impoundments to store tailings. ST Equipment & Technology can help. Our triboelectrostatic belt separation systems can separate fine particles, providing valuable material recovery from waste stream. The STET process is high feed rate, low energy and operating cost and high reliability. In short – it is good for your business and it’s good for the environment.

Contact ST Equipment & Technology today to learn more!