The stockpile built up to 100,000t after the global pandemic impacted markets, with Image's Chinese offtake partners Natfort and OZC now agreeing to buy the HMC over a 3-5-month period.
"Pricing is based on current market prices and will be locked for the full 100,000 tonnes to protect against any unanticipated softening of the market during the delivery period," Image said.
In addition, discussions with "several" other potential buyers are said to be underway, and Image believes success on this front "will serve to monetise Image's current surplus HMC inventory across the next 3-4 months, and maintain more timely sales of ongoing production".
Image started the recently completed June quarter with A$41 million cash and $53 million of debt.
Cashflow in the March quarter from the Boonanarring project north of Perth was $5.2 million, with that amount achieved despite one of the company's planned three HMC shipments not occurring - leading to the build-up of inventory now being sold.
Shares in Image rose more than 9% to 17.5c with the news of the HMC sales, with the stock having gained more than 6% Monday.
At 17.5c, Image is capitalised at $172 million.