Resin potential factor in Grosvenor blast

The use of a large quantity of polyurethane resin to consolidate the face and roof at longwall 104 is among the issues an inquiry will examine as it looks to determine the cause of the Grosvenor mine explosion. Counsel assisting the Queensland Coal Mining Board of Inquiry Jeffrey Hunter said it would be raised as a potential source of ignition for the May 6 blast that injured five men. Mixing of the components causing the polyurethane resin (PUR) toexpand and harden leads to an exothermic reaction, with the materail heating to high temperatures when curing. Mr Hunter told the inquiry the PUR injected into the Grosvenor longwall face on March 26, April 16 and May 3 last year was a product called Strata Bond HA suppliued by DSI. Mr Hunter said Simtars executive mining engineer Martin Watkinson hypothesised that the use of PUR in the May campaign, particularly in the quantities involved, may have resulted in a localised heating event sufficient to ignite an explosive mixture of gas in the goaf fringe. "It is proposed to examine this hypothesis in the course of the hearings," he said. Mr Watkinson is among a raft of expert witnesses set to testify as the Board of Inquiry enters its second round of public hearings. The hearings will focus on the serious accident at Anglo American's Grosvenor mine on May 6, 2020 and the 27 methane exceedances at longwalls 103 and 104 that occurred between July 1, 2019 and May 5, 2020. In opening remarks today, Mr Hunter said the Mines Inspectorate's investigation into the May 6 incident had progressed substantially, although it was not yet concluded. "A body of evidence comprising a range of expert opinions in a variety of disciplines relevant to an assessment of the explosion at Grosvenor mine and its possible causes has become available," he said. The Board of Inquiry has heard that over the relatively short period it was in operation, longwall 104 accumulated 14 methane exceedance HPIs. Pressure waves strong enough to knock workers off feet The serious accident involved a methane explosion about 2.57pm on May 6, which caused the five workers to suffer burn injuries. Mr Hunter said coal mine workers underground at the time of theaccident experienced pressure waves with sufficient force to knock workers off their feet. It was noted that a worker at number 6 cut-through - 3.5km from the face - stated that he experienced two pressure waves and his ears popped. "The fact of the injuries (to the five workers) demonstrates the presence of an explosive mixture of air and methane towards the tailgate end of the longwall face at that time, despite the ventilation and other controls the mine had put in place in an attempt to guard against such an occurrence," Mr Hunter said. "There must also, though, have been a source of ignition present to cause the methane mixture to explode, and so the two fundamental questions are therefore: how did an explosive mixture of air and methane come to be onthe longwall face at that time; and what was the source of ignition?" The evidence began with Resources Safety & Health Queensland Regional Inspector of Mines Stephen Smith, who is due to continue his testimony Wednesday.

Resin potential factor in Grosvenor blast

Industry Queensland

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