Groutech says it has effectively demonstrated the benefits of this consolidation process at various coal mines across Queensland and NSW.

The main area of grouting interest for coal mines is strata control – in particular, areas in and along fault zones in longwall mines. Cave-ins are often experienced when mining through fault zones and the likelihood and severity of the caving is affected by a large number (and combination) of variables, which include:

Size, type and orientation of fault;

Mechanical condition of the longwall;

Experience of the longwall operators; and

The desire to maintain longwall momentum.

When the mining industries expressed a desire to bring the benefits of construction practices into the mining industry in 1998, the Australian Coal Association Research Program (ACARP) approached Groutech to learn more about civil engineering grouting practice and how it could assist strata control in longwall mines.

This led to onsite grouting trials at North Goonyella Mine, proving that cementitious grouts could be injected into coal and faulted zones. It was very clear that the grouting expertise and technique was far more important than the products used.

Groutech has since been invited to discuss fault zone consolidation on numerous minesites as well as participating in risk assessments for mine planning. Other grouting applications of interest to coal mines include:

Reducing permeability – preventing water inflow to underground workings, vent shafts and dam curtains;

Reducing air flow – to improve seals and for spontaneous combustion prevention; and

Backfilling to control subsidence.

A recent shift in mind-set has occurred towards a more proactive approach to consolidation, hence the name “Pre-consolidation”.

“Groutech’s proven success of using intrinsically safer cementitious grouts, and consolidating the strata in advance of the longwall, has encouraged this thinking,” the company said.

“This form of consolidation has the potential to reduce the need for remedial polyurethane [PUR] injection and the associated dangers using chemical grouts.”

Groutech said numerous mines in the Bowen Basin have employed cement consolidation grouting and ACARP has also engaged cement grouting in consolidation trials.

“Results and performance reviews indicate little to no longwall down time while mining through grouted zones that have been grouted by Groutech.”

Through consultation with proven consolidation grouting specialists, some mines have designed site-specific grouting programs with convincing results. Successful results have come from mines that have incorporated consolidation grouting into their fault zone strategy. Regular discussion, programming the works and allocating budgets for the work is part of this strategy.

Successful approaches include:

Identifying faults considered to be at risk of caving well prior to mining;

Drilling boreholes to gain geotechnical information;

Using a specialist grouting contractor to consolidate the zone via the boreholes as opposed to would-be grouters; and

Careful planning and preparation to ensure the longwall and staff are prepared to manage approach rates.

Groutech said the current frequency of consolidation grouting on any one mine is insufficient to warrant the specialist training and expense associated with purpose-built equipment to grout in-house.

“Often the cost to drill the hole is greater than grouting the hole,” the company said.

“To maximise grouting effectiveness and value for the drilling dollar, a specialist contractor with a proven track record should be engaged to assist with the design of the drilling and grouting program.

“High global coal prices have resulted in increased production. Down time is no longer acceptable in the race to maintain productivity and while coal prices will fluctuate, the industry’s emphasis on safety and efficiency will remain high,” the company said.

Still in its relative infancy, this proactive form of grouting provides more consistent productivity, confidence, a safer work environment, and control through budgeting and planning, Groutech said.

“Effective consolidation grouting using proven specialist grouting contractors will play an increasing role in years to come,” the company said.

Groutech’s services extend to:

Mining;

Shires and councils;

Government departments – QR, Main Roads;

Consulting engineers; and

Industrial and commercial clients.

“Our Quality Assurance, staff training and job-specific planning combine to provide our customers with a professional service. This has resulted in a strong repeat business relationship we share with many of our customers. We, like you, have an enormous amount of pride in what we do. We distinguish ourselves from others in our ability to provide solutions through knowledge, experience, techniques and understanding,” Groutech said.

“When you think grouting, think ‘Groutech’.”