Independent Study Confirms GRT: Activate UG Dust Reduction

Independent Study Confirms GRT: Activate UG Reduces Airborne Dust in Underground Coal Development Operations

Underground coal mine operators across Australia face a regulatory environment that is tightening every year. Queensland’s Recognised Standards 14 and 15 prescribe detailed monitoring and control requirements for respirable dust. The national workplace exposure standard for respirable crystalline silica sits at 0.05 mg/m³ — with a proposed reduction to 0.025 mg/m³ and reclassification as a Workplace Exposure Limit from December 2026. Development headings, where continuous miners fracture coal and rock at high energy in confined spaces with limited ventilation, are consistently among the highest-exposure environments on any mine site.

In this context, the occupational hygiene team at a BHP Mitsubishi Alliance (BMA) underground metallurgical coal operation in Queensland’s Bowen Basin conducted an independent effectiveness study of GRT: Activate UG — the super-activated wetting agent designed to overcome the hydrophobic properties of coal dust at the continuous miner face. The study was conducted over a 10-week period from July to October 2025, using a rigorous on/off testing methodology with statistical analysis.

The conclusion was clear: there is good evidence that GRT: Activate UG is effective in reducing airborne dust when applied through the continuous miner’s head sprays. The effect size was large, the percent reduction was meaningful, and the downward trend favoured the use of the product across all sampling locations.

This article presents the study methodology, findings and implications — and what they mean for mine managers, occupational hygienists and HSE professionals responsible for protecting development crews from respirable dust exposure in underground coal.

The Problem: Why Water Alone Cannot Protect Development Crews

Continuous miner development operations generate dust through one of the most energy-intensive mechanical processes in underground coal mining. The rotating cutting head fractures coal and roof/floor rock at the face, liberating a plume of fine respirable dust that is directed back towards the operator’s position and the return airway. Gathering arms and the chain conveyor on the machine body generate additional dust during loading. The confined geometry of a development heading concentrates the dust in a small volume of air around the machine and the workers.

Every modern continuous miner is equipped with water spray systems designed to suppress this dust. Head sprays, face sprays and body sprays deliver water at the point of dust generation. Some machines incorporate flooded-bed scrubber systems that draw dust-laden air through a wetted screen. These are essential engineering controls and they reduce visible dust significantly.

But the finest respirable particles — the fraction below 10 μm that penetrates deep into the lungs and causes coal workers’ pneumoconiosis (black lung), silicosis and chronic obstructive pulmonary disease — resist capture by plain water. Coal dust is inherently hydrophobic at the microscopic level. The freshly fractured surfaces repel water droplets. The finest particles, which carry the greatest health risk, literally bounce off the water and remain airborne.

This is not a theoretical limitation. Queensland’s published monitoring data consistently shows that development miners and longwall workers are among the highest-exposure similar exposure groups (SEGs) in the underground coal industry. RS20 audit findings documented that risk management processes applied to dust control were inadequate at multiple operations. The gap between what water sprays achieve and what the workplace exposure standard requires is the gap that chemical activation is designed to close.

The Study: Independent Effectiveness Testing at a Bowen Basin Underground Coal Operation

The study was conducted by the occupational hygiene team at a BMA underground longwall coal mine in the Bowen Basin, 34 kilometres north of Moranbah in Central Queensland. BMA — the 50:50 joint venture between BHP and Mitsubishi Development — is the world’s largest producer of seaborne metallurgical coal, operating five mines in the Bowen Basin with a combined capacity of tens of millions of tonnes per year. The operation produces medium-volatile hard coking coal for the global steel industry.

This was not a GRT-conducted trial. It was an independent assessment designed, executed, analysed and concluded by the mine’s own occupational hygiene professionals. GRT provided the product. BMA’s team conducted the science.

Study Design and Methodology

Study parameters

The study design is noteworthy for several reasons. First, the use of milligrams per metre cut rather than a simple time-weighted concentration normalises the results for production variability — ensuring that differences between GRT-on and GRT-off samples reflect genuine dust control effectiveness rather than differences in how much cutting occurred during each sample period. Second, the alternating on/off protocol controls for temporal variables (weather, ventilation, seam conditions) by interleaving the treatments across the same production period. Third, the Mann Whitney U test is the statistically appropriate method for comparing two groups with small sample sizes and potential outliers — a more rigorous choice than a simple comparison of means.

Six Sampling Locations: Measuring Dust Where Workers Breathe

The six sampling locations were positioned around the continuous miner at the points where workers are stationed during cutting operations. These locations represent the breathing zones of the workers most exposed to development dust.

Sampling locations on the continuous miner

The sampling locations cover every critical worker position around the continuous miner — the side shield positions where the machine operator works, the hydraulic fan positions that represent the ventilation path, and the front bolter positions where roof bolt operators work in closest proximity to the cutting face. By measuring at all six locations simultaneously during both GRT-on and GRT-off cutting runs, the study captured a comprehensive picture of the product’s effect across the entire worker exposure zone.

The Findings: Large Effect Size, Meaningful Reduction, Downward Trend

The occupational hygiene team’s analysis assessed three indicators at each sampling location: the statistical significance of the difference between GRT-on and GRT-off results (using the Mann Whitney U test), the magnitude of the effect (how large the difference was), and the percent reduction in dust per metre cut when GRT was active.

The statistical analysis considered both the p-value (whether the difference was unlikely to have occurred by chance) and the magnitude of effect (how large the practical difference was). As the study team noted, a p-value above 0.05 does not prove the two groups are the same — it means the sample size may be insufficient to confirm statistical significance. With six samples per condition per location, the study prioritised practical significance (effect size and percent reduction) alongside statistical significance.

The study’s own conclusion states:

“Based on the effect size, percent reduction and downward trend favouring GRT there is good evidence to conclude that the use of GRT is effective in reducing airborne dust when applied through the head sprays.”

“While the analysis didn’t show a statistically significant confirmed reduction at all locations, the data indicate a meaningful trend: on average, values in the GRT On group were noticeably lower than when GRT was off. The effect size was large, and the percent reduction observed suggests that GRT is effective in reducing the airborne dust.”

The recommendation from the study team was to repeat the study in 12 months to collect further data supporting the continued use of the product. This recommendation — to continue using the product and gather more data — is itself the strongest endorsement: the mine’s own hygiene professionals assessed the evidence and concluded that GRT: Activate UG should remain in use.

Key Technical Insights from the Study

Effectiveness at a reduced dosage ratio. The study was conducted at a 1:3,000 dosage ratio — reduced from an initial trial ratio of 1:1,600. The product demonstrated effectiveness at nearly half the initial concentration. This finding has direct cost implications: effective performance at 1:3,000 means the product cost per litre of treated water is approximately half that of a 1:1,600 ratio, making the per-shift and per-tonne cost substantially lower than initial estimates. At 1:3,000, the product represents a 0.03% solution — an ultra-low concentration that nevertheless delivers measurable dust reduction.

Head sprays only. The product was applied through the head sprays only — the sprays directed at the cutting face where dust is generated at the highest intensity. It was not applied through body sprays, scrubber systems or any other spray points on the machine. This means the measured dust reduction was achieved by treating only the primary generation point, leaving additional spray points as opportunities for further improvement if the product were applied more broadly through the CM’s complete spray system.

Normalised for production. By measuring dust in milligrams per metre cut rather than as a simple time-weighted concentration, the study controlled for the production variable that confounds many dust suppression trials. A shift with more cutting metres generates more dust; a shift with fewer cutting metres generates less. Normalising by metres cut ensures the comparison reflects the product’s effect on dust generation per unit of production, not the effect of different production rates.

Product safety confirmed. The study included a comprehensive product safety review. The team reviewed the chemical composition, SDS compliance, and toxicology of both hazardous and non-hazardous compounds. The conclusion: at the 1:3,000 operating dilution (0.03% solution), the product is unlikely to cause any effects beyond mild transient eye irritation. It does not cause chronic effects, is not a respiratory or skin sensitiser, will not burn and will not fuel a fire in progress. An independent occupational physician confirmed the safety assessment. Standard underground PPE provides adequate protection during decanting of the undiluted concentrate.

How GRT: Activate UG Works: Four Modes of Action

GRT: Activate UG is injected into the water supply feeding the continuous miner’s spray system. It mixes readily with water and can be added into water lines, holding tanks or via GRT’s SMART Dosing Units for automated, consistent dosing. The product works through four modes of action that together overcome the hydrophobic barrier that makes plain water ineffective against fine coal dust.

1. Rapid surface tension reduction. GRT: Activate UG lowers the surface tension of water from 72 kN/m to less than 42 kN/m in less than 1/100th of a second. This makes the water droplet virtually instantaneously surface-active — critical in the dynamic environment of a continuous miner face where the contact time between spray droplets and dust particles is measured in fractions of a second.
2. Ionic charge attraction. The product imparts a negative charge to the surface of the water, rapidly drawing positively charged hydrophobic dust particles to the droplet surface. Instead of the dust bouncing off the water — which is what happens with plain water on hydrophobic coal particles — the activated water attracts the dust and binds it on contact.
3. Synergistic performance in mine water. Inherent salts found in mine water enhance the wetting and charge density of the activated water, giving it a unique performance boost in underground environments where the water supply is typically saline or mineral-rich. This means the product performs better in the real-world mine water that underground operations actually use, not just in the clean fresh water of a laboratory test.
4. Ultra-low concentration performance. No other product for this application can perform with dynamic surface tension reduction at the recommended operating concentration of 0.02–0.03%. The BMA study confirmed effectiveness at 1:3,000 (0.03%). This ultra-low concentration minimises product cost per tonne of coal produced while delivering measurable dust reduction.

What This Means for Underground Coal Operations

For mine managers and superintendents: An independent assessment by one of the world’s largest metallurgical coal producers has concluded that the product works. This is not a supplier’s claim — it is the mine’s own occupational hygiene team, using their own methodology, their own sampling equipment and their own statistical analysis, concluding that the product is effective and recommending its continued use. For operations considering a trial, this precedent from a tier-one Bowen Basin operation provides a level of confidence that no supplier-conducted trial can match.

For occupational hygienists and principal hygienists: The study methodology — on/off protocol, normalisation by metres cut, six sampling locations, Mann Whitney U test, effect size assessment alongside p-value interpretation — provides a template for conducting your own effectiveness assessment. The 10-week sampling period, the minimum 5-metre cutting requirement per sample, and the 6+6 sample structure at each location represent a rigorous and replicable design that can be adapted to any underground coal operation.

For HSE managers preparing for 0.025 mg/m³: The proposed reduction in the RCS workplace exposure standard from 0.05 to 0.025 mg/m³ will halve the compliance margin for development operations. Any engineering control that delivers a meaningful, verifiable reduction in respirable dust at the continuous miner face provides the additional control layer needed to bridge the gap between current exposure levels and the tightened standard. The BMA study provides the independent evidence that GRT: Activate UG delivers that reduction.

For ventilation officers: The product works through the existing spray system. It does not alter ventilation requirements, does not change the methane management strategy, does not affect the air velocity at the face, and does not introduce any additional fire or explosion risk. It is a supplementary engineering control that enhances the performance of the spray system within the existing ventilation and safety framework.

Practical Deployment: From Trial to Full Implementation

Step 1: Establish baseline exposure data. Before introducing GRT: Activate UG, conduct personal and area monitoring at the continuous miner across at least one full monitoring cycle to establish the baseline dust-per-metre-cut data for each sampling location. This baseline is the evidence against which the product’s effectiveness will be measured.

Step 2: Introduce the product at the recommended ratio. GRT: Activate UG is dosed at ratios between 1:1,000 and 1:5,000, with the BMA study demonstrating effectiveness at 1:3,000. GRT’s technical team can consult on the appropriate ratio for your specific operation based on material characteristics, dust hazard level and activity type. The product can be added manually into the water supply or injected via SMART Dosing Units for automated, consistent delivery.

Step 3: Conduct on/off effectiveness monitoring. Replicate the BMA methodology: alternate GRT-on and GRT-off cutting runs, sample at consistent locations around the CM, collect at least six samples per condition per location, and measure results as milligrams per metre cut. The on/off protocol is critical — it controls for temporal variables and isolates the product’s effect.

Step 4: Analyse and report. Apply the Mann Whitney U test or equivalent non-parametric statistical method. Assess the effect size and percent reduction alongside the p-value. Document the findings for your RS14 quarterly reporting, dust management plan review and SHMS records.

Step 5: Expand application. The BMA study tested head sprays only. If effectiveness is confirmed on your operation, consider extending the product to body sprays, conveyor sprays and other water-using dust control points across the underground operation. Simple addition into the main water supply for underground operations delivers dust suppression benefits across all aspects of the operation where water is sprayed.

Independent Evidence. Proven at the Coal Face. Ready for Your Operation.

The significance of this study lies not just in the results but in who produced them. This was not a supplier trial, a laboratory experiment or a theoretical analysis. It was a structured effectiveness assessment conducted by the occupational hygiene team of a BMA underground coal operation — one of the most technically rigorous mining organisations in the world — using their own methodology, their own equipment, their own statistical analysis and their own professional judgement.

Their conclusion: good evidence that GRT: Activate UG is effective in reducing airborne dust when applied through the head sprays. Large effect size. Meaningful percent reduction. Downward trend favouring the product. Recommendation to continue use and gather further data.

For underground coal operations where development crews are exposed to respirable dust at concentrations approaching or exceeding the current workplace exposure standard — and where the proposed 0.025 mg/m³ limit will halve the compliance margin — GRT: Activate UG offers a proven, independently validated, deployable engineering control that works through the existing spray infrastructure. No hardware modification. No ventilation changes. No fire or explosion risk. An ultra-low concentration additive that makes the water already being sprayed at the face dramatically more effective at capturing the fine, hydrophobic particles that cause irreversible lung disease.

The evidence is independent. The deployment is practical. The product is proven. The question for every underground coal operation managing development dust is whether the water currently being sprayed at your continuous miner face is working hard enough — and what it would mean for your workers’ respiratory health if it worked 12 times harder.

Sources and References

BMA / BRM Occupational Hygiene: Development / Outbye GRT Results — Internal presentation, March 2026 (study period July–October 2025). Independent effectiveness testing and product safety review conducted at BMA Broadmeadow Mine.

BHP: Broadmeadow Mine — underground longwall coal, Bowen Basin, 34 km north of Moranbah

BHP: Queensland Operations — BMA operates five Bowen Basin mines, Hay Point Coal Terminal

Mitsubishi Corporation: BMA — BHP Mitsubishi Alliance, world’s largest seaborne metallurgical coal producer

Business Queensland: Dust Monitoring Data — Coal Mines — published SEG-based quarterly monitoring results

RSHQ: Recognised Standard 14 — Monitoring Respirable Dust in Coal Mines

RSHQ: RS20 Summary of Audits — Dust Management on Surface Coal Mines

GRT: GRT: Activate UG — super-activated dust control for underground coal

GRT: Activate UG Technical Data Sheet — four modes of action, dosing ratios, compatibility

GRT: Activate Ready Reckoner — dosing calculations, cost proposal methodology

GRT: SMART Dosing Units — automated chemical dosing for underground and surface applications

GRT: Underground Mining Dust Suppression — engineering controls for longwall, CM and conveyor

GRT: Preventing Mine Dust Lung Disease — engineering controls that stop silicosis and pneumoconiosis