Grosvenor production was suspended following a May 2020 underground explosion that injured five coal mine workers.
The company said in its September quarterly report that export metallurgical coal production had decreased 11% to 4.3 million tonnes due to operations at Grosvenor's neighbouring Moranbah mine being impacted by challenging geological conditions.
"This was partly offset by Dawson and Capcoal increasing production levels after having scaled back production volumes since mid-2020 in response to reduced demand for their particular products," it said.
"Development activities at Grosvenor continue as part of the mine's staged approach to restarting longwall mining operations towards the end of 2021, subject to the approval of the Queensland Mines Inspectorate, with the first development coal washed in September."
The ratio of hard coking coal production to pulverised coal injection/semi-soft coking coal was 83:17, slightly higher than in Q3 2020 due to solid performances at Anglo American's Grasstree mine and the mine sequence at its Dawson and Capcoal mine in Queensland.
The year-to-date average realised price for hard coking coal was US$149 per tonne, lower than the benchmark price of $177/t as sales for the year have consisted of a lower proportion of premium quality hard coking coal from Moranbah and Grosvenor.
Anglo American said production guidance was unchanged at 14-16Mt, subject to the extent of any COVID-19 related disruption.