The company is going through an approvals process for its new Bungalbin East (BE) and Jackson 5 (J5) mines north of Southern Cross.
The approvals are subject to an environmental review by the Environmental Protection Authority, with the comment period set to close on Monday.
MRL employs 79 staff at its Kwinana bulk iron ore export terminal and 148 staff at its workshop and logistics hub to support mining operations.
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“These are real jobs which have feet in boots now, but will (be) lost if approvals are not granted,” it said.
A spokesman said the mine approval would altogether support 1500 jobs and mining activity beyond 2030 while paying over $1 billion into government coffers.
“MRL is currently the Fremantle Port Authority’s biggest customer as measured by volume and value,” he said.
Yilgarn Iron Producers Association chief executive David Utting said J5 was a granted mining lease and BE was a pending mining lease.
“Mining at J5 and BE will disturb less than 1.6 per cent of the total area of landforms within the Mt Manning area,” Mr Utting said.
He said MRL’s mining operations in the Yilgarn were forecast to deliver several hundred million dollars in royalties to the West Australian economy over coming years.
“In financial year 2016, MRL’s Yilgarn iron ore operations contributed almost $67 million to the government through royalties, port fees, local government rates, payroll tax and company tax,” Mr Utting said.
A company statement said: “If MRL’s mining proposal gets the go-ahead, the establishment of the two new mines will allow all significant benefits to continue beyond 2030”.