The deal will give SQM a foothold in Australia with a stake in Azure's Andover project.
Australia's Azure Minerals said on Wednesday the country's Foreign Investment Review Board (FIRB) extended a deadline for approving SQM and Hancock Prospecting's A$1.7-billion offer for the lithium developer.
The deadline for granting the approval has been extended to April 30 from April 10.
"This is a standard extension request and Azure is not currently aware of any reason that the required FIRB approval will not be received," the company said in a statement.
Chilean miner SQM and Australia's richest person Gina Rinehart's Hancock Prospecting, already Azure's two largest shareholders, teamed up in December to buy the lithium developer.
China's Tianqi Lithium holds about 20% of SQM shares, and the deal would give SQM, the world's No.2 lithium producer, a foothold in Australia with a stake in Azure's Andover project.