Rejects or fine coal Tailings Backfill is the process of utilising waste products from the CHPP (rejects and tailings) to make a pumpable paste for delivery into the old workings.
As a reject disposal method, backfill is more expensive (per tonne of reject) than normal surface emplacement methods so it is not the lowest cost option, unless there is a specific reason. This reject utilisation method may actually make some operations more viable due to the cost of existing constraints.
Reasons for utilising rejects or coal tailings as backfill may include:
- insufficient surface area, or environmental approval constraints, to enable the construction of a Tailing Storage Facility (TSF)
- the goaf gas management is managed via goaf entombment using hydraulically delivered backfill
- the cost of the backfill plant (between $8M and $14M) can provide up to $20M to $50M in operational savings by utilising cement blended fill UG. Delivered via an underground reticulation system, the cement blended fill is used to construct concrete roadways and bulkheads
A number of studies have been performed for Metropolitan Colliery, New Hope, Tahmoor and Springsure and Newlands Coal Mine.
Tim Gilroy was Minecraft Project Manager for backfill, washplant, coal handling, supply chain, water balance and surface infrastructure. Tim delivered an innovative backfill plant essential for project viability from desktop to European lab trials to Australian lab trials to pilot scale then to full scale.
