The Board's final report was prompted by a serious accident that occurred at Grosvenor's longwall 104 on May 6 2020 in which five mine workers were injured.

"The gas emissions being generated by the mine's rate of production were in excess of the capacity of the mine's gas drainage system," the report said.

"Producing coal at a rate that consistently exceeds the capacity of the critical control of gas drainage subjects coal mine workers to an unaccpetable level of risk.

"It follows that coal mine workers on LW 104 were repeatedly subject to an unacceptable level of risk." 

Grosvenor mines the GM [Goonyella Middle] seam in the typical manner, which involves leaving significant remnant coal in the goaf, the report found. 

"This significantly increases the risk of spontaneous combustion," it said.

"Notwithstanding the sophistication of gas monitoring systems such as those in use at Grosvenor, there are practical limitations to the efficacy of monitoring regimes for spontaneous combustion, including the element of human error.

"In the Board's view, spontaneous combustion was the probable cause of the serious accident.

"It was also the cause of an ignition that occurred at Grosvenor on June 8 2020. The occurrence of these events, despite the use of conventional monitoring systems that did not clearly detect them, is of major concern."

The Board said the deficiencies of sponcom identification and monitoring systems provide reason to consider the role of proactive inertisation of the active goaf, in conjunction with those systems.

"Active goaf inertisation involves creating an inert atmosphere in goaf areas by means of injecting an inert gas, such as nitrogen, to reduce oxygen concentrations to a low level that would effectively suppress or contain the onset of spontaneous heating," it said.

"Studies have shown that proactive inertisation can be successful in reducing oxygen concentrations in the active goaf in Australian mines.

"Technology has advanced to the point where the infrastructure is available for delivery of the required volumes of nitrogen."

The Board said the principal benefit lies in a significant reduction in the proportion of the goaf which is susceptible to spontaneous combustion or methane ignition.

"Safety risks and production losses are correspondingly reduced," it said.

"Notwithstanding some debate over the impact of inertisation on the utility of some traditionally used indicators of spontaneous combustion…the design and implementation of proactive inertisation should be considered as a measure to deal with the risk of spontaneous combustion.

"This would be particularly so for mines working the GM seam."

The Coal Mining Board of Inquiry's final report paints a shocking picture of safety management at Grosvenor, finding that workers at the underground coal mine were exposed to unacceptable risk for months before last May's explosion, according to Construction, Forestry, Mining and Energy Union Queensland resident Stephen Smyth.

He said the most shocking thing to come out of the report was the detailed account of Anglo's failure to manage dangerous gases at Grosvenor in the months leading up to the blast.

"I felt sick reading the detail about Anglo's recklessness," Smyth said.

"Management knew there were problems following a series of high potential incidents during March and April, but did not slow coal production to match its gas drainage capacity.

"The report clearly finds that ‘coal mine workers were repeatedly subject to an unacceptable level or risk'.

"Last year's explosion was a shocking and traumatic event and it makes my blood run cold to think that the outcome could have been much worse.

"Coal mine workers put their lives in the hands of mine managers every time they go to work and they should be able to have confidence every possible measure is in place to protect them. They have been seriously let down in this case."

Smyth said the union would work hard to make sure the Inquiry's findings lead to systemic improvements in the industry - including employment practices.

The report looks at the extensive use of casual labour hire in Queensland's coal mining industry, finding that there is widespread perception among contractors that they could lose their job if they raise a safety concern and that there is no obligation for mine operators to inform labour hire companies over worker safety risks.

However, the report notes a lack of research into the full effects of workforce casualisation in the mining industry.

Smyth said a further Inquiry focused on the widespread replacement of permanent direct jobs with casual labour hire in the mining industry was necessary to understand the relationship to safety outcomes.

"It's not good enough for mine operators to just assert that casualisation is fine and dandy," Smyth said.

"It's certainly not the view of workers on the ground that removing rights and job security is conducive to a good safety culture. There is more work to be done to tackle this toxic business model."

Anglo American Metallurgical Coal business CEO Tyler Mitchelson said the company is already acting on the recommendations of the Board of Inquiry's report, including $60 million of investment in safety initiatives over the last year.

"We are today committing a further $5 million to fund underground mining research, in partnership with our industry research and technology partners, to improve the industry's knowledge in certain technical areas," he said.

"We have been clear from the outset that the incident on May 6 2020 in which five of our colleagues were badly injured was unacceptable. The safety of our workforce is always our first priority.

"Over the past 12 months, we have put in place a range of measures to address issues that have come to light through detailed investigations and evidence before the Board of Inquiry.

"Over this period, we have already committed more than $60 million in technology pilots, additional gas drainage infrastructure, expert reviews and further improvements to a range of processes and controls.

"Underground coal mining, particularly in the area where Grosvenor Mine is located, is complex with many interacting considerations and, as the Board has identified, further research into certain technical areas such as gas and spontaneous combustion management would benefit the industry. We will be helping to advance knowledge in these areas through our further $5 million funding commitment."

Mitchelson said Anglo American's Operating Model, our primary operational management system, is currently being updated at Grosvenor and, together with a range of other measures such as the use of data science, will ensure we have the very latest in systems thinking, design and technology to ensure operational stability and control, and ultimately safe production. 

"The Board of Inquiry's reports have made a number of recommendations, and we are confident we have already addressed, or will address, these ahead of the restart of longwall mining at Grosvenor Mine later this year," Mitchelson said.

"The use of automation and remote operation presents us with the single biggest opportunity to remove people from high risk areas and we are fast-tracking this work across our operations, including commissioning ground-breaking research into automation in development mining with CSIRO."

Mitchelson said that following the implementation of the recommendations from the Board of Inquiry, the industry would be safer. 

"The Board of Inquiry undertook a very thorough examination of a range of issues relating to underground coal mining, and we have been committed to learning everything we can from the process and acting as quickly as possible to implement improvements,"he said.

"Over the past 12 months, we have engaged closely with our workforce, particularly at Grosvenor, as we've worked through the issues and resumed underground activities at the mine last month. We are continuing to support all of our colleagues involved in the incident in May last year, and this will remain a priority for our team."