GEM Projects
GEM Projects is an experienced mine backfill company providing innovative backfill services, from tailored fill design solutions to onsite execution.
We specialise in the placement of cost effective, high performing backfill to provide underground strata support, Longwall recovery (PDRR), ventilation control, monolithic seals, high-volume/long distance pumping, specialised alternate concrete/grout mixes, with proven QA/QC methodologies to demonstrate our proficiency.
GEM Projects provide first class compliance, safety, environmental and quality standards with pioneering mining techniques. Our focus on innovation drives continuous improvement and ensures our service remains at the forefront of industry.
Backfill is also known as grouting, flowable fill, ground stabilisation, etc.
This includes:
- Backfilling roadways to improve Longwall recovery – Pre-Driven Recovery Roads (PDRR)
- Backfilling mine workings/stopes to improve ground support & resource recovery
- Backfilling mine workings to improve ventilation or control heating events
- Backfilling highwall mining to improve resource recovery
- Backfilling old mine workings to protect surface infrastructure & promote development of surface infrastructure
About us
Tim Gilroy is the owner of GEM Projects. Tim is a certified Mechanical Engineer with Masters Degrees in both Materials Handling and also Project Management, combined with specialist plant design expertise.
WHAT WE DO
Fly ash Backfill
The use of fly ash in backfill for the following reasons:
- Lowest cost option
- Fly ash is complementary to the cement binding reaction whereas tailings requires more cement to cure
- Fly ash is a waste product from Coal Fired Power Stations, comprised of round spherical <150 micron, amorphous incombustibles
- Dry pneumatic handling = fully sealed handling.
GEM Projects sources and delivers fly ash grouts
GEM Projects has project managed 8 PDRR projects in QLD and NSW
Pre-Driven Recovery Roadways
Longwall operations implement PDRRs to realise safety and productivity benefits. PDRRs involve:
- Development of an additional roadway (single or double pass) at the LW take off
- Installation of secondary support and pressure rated shutters along the roadway and affected intersections
- Fully backfilling the PDRR with a specifically designed low strength cementitious grout delivered via boreholes.
- LW shearing into the grout filled PDRR at close to full production rates and is recovered from within the supported roadway.
Oxidation Control
Involves the use of backfill to suppress and/or control oxidation in underground coal mines.
GEM Projects methodology include proven SWMS, risk assessments and delivery of all site services. Oxidation control options include:
- Dry fly ash suppression of goaf oxidation via surface borehole/s
- Wet fly ash smothering of known oxidation zone in the goaf via surface borehole/s
Dry fly ash construction of a roadway seal remotely via borehole/s.
GEM Projects for all your mine backfill contract services
GEM Project Manages disposal of coal rejects and tailings underground
Coal Reject Backfill
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 or 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.