Global mining giant BHP has been circling the Adelaide-headquartered copper and gold miner since early last year when its first $8 billion bid to take over OZ Minerals was swiftly rejected by its board.

Now, though, the company that is listed at number two behind Santos in InDaily’s South Australian Business Index of the state’s top companies, has its board unanimously backing BHP buying all of its shares at a cash price of $28.25 per share.

OZ Minerals board chair Rebecca McGrath urged a yes vote in a letter to its more than 43,000 shareholders telling them of the meeting at OZ Minerals’ Adelaide Airport office.

If the sale goes ahead, BHP will take control of the company’s famed copper and gold mines at Prominent Hill and Carrapateena mines in the state’s north along with its high-potential West Musgrave copper and nickel project in Western Australia.

“I look forward to your participation at the Scheme Meeting and encourage you to vote in favour of the Scheme, subject to the Independent Expert continuing to conclude that the Scheme is in the best interests of OZ Minerals Shareholders and there being no Superior Proposal,” McGrath wrote in the March letter to shareholders.

McGrath had labelled BHP’s first offer in August last year as “highly opportunistic”.

Mining and Energy Minister Tom Koutsantonis said while he would be “sorry to see OZ Minerals go” the company’s work on building “two great copper deposits will continue no matter who owns the company”.

“They’ve done a great job to set SA up for prosperity and the state should be grateful for the job Terry Burgess (former managing director and CEO), Andrew Cole (current managing director and CEO) and Rudy Gomez (prospector who found Carrapateena) have done in building this SA-headquartered company,” Koutsantonis said.

“We want the company to remain here, and we want its workers to remain here. But the legacy of those two deposits will continue, whoever owns OZ Minerals.”

An OZ Minerals spokeswoman said the company employs about 660 South Australians.

Clearance for the sale has been given by the Brazilian competition regulator in relation to OZ Minerals’ Santa Lúcia iron oxide copper-gold mineral deposit, the Antas copper-gold mine, and CentroGold, one of the largest undeveloped gold projects in Brazil.

But the “scheme of arrangement” must be voted on by more than half of OZ Minerals shareholders voting at the meeting and at least 75 per cent of the total number of votes cast must be in favour.

OZ Minerals’ meeting follows last week’s announcement that the OTR Group, one of South Australia’s largest employers with around 200 petrol and convenience stores across the state, was bought by Victorian-based fuel supplying company Viva Energy.

South Australian Chamber of Mines and Energy (SACOME) chief executive Rebecca Knol said OZ Minerals has been a significant contributor to the South Australian resources sector, starting out as an explorer and growing into a developer and now successful operator.

“OZ Minerals has demonstrated leadership in innovation, sustainability, engagement with landowners, and close collaboration with stakeholders and business,” she said. “SACOME is proud to have represented OZ Minerals for almost 20 years.”

She echoed Koutsantonis’s comments about the value of the company’s SA operations.

“Regardless of the outcome, Carrapateena and Prominent Hill remain vital mineral assets for the state and will continue to benefit South Australians for years to come.”

OZ Minerals owns some of the nation’s highest potential mining assets.

Prominent Hill is 130km southeast of Coober Pedy and the company says it produces one of the highest-grade copper concentrate traded on the open market, while Carrapateena is “one of the largest undeveloped copper deposits in Australia”.

The letter to OZ Minerals shareholders said the meeting this week would allow them to vote on the “proposed scheme of arrangement” where BHP Lonsdale Investments Pty Ltd, a wholly owned subsidiary of BHP Group Limited, “has agreed to acquire 100 per cent of the shares in OZ Minerals for $28.25 per OZ Minerals Share”.

This is comprised of “$26.50 for each OZ Minerals Share held on the Scheme Record Date and a fully franked Special Dividend of $1.75, for each OZ Minerals Share they hold on the Special Dividend Record Date.”

In its Economic Contribution Report released in September last year, BHP said it employed more than 10,000 South Australians and spent $1 billion with local suppliers in the previous financial year.

Earlier that month it announced record profits with underlying earnings of $57 billion, boosted by higher copper prices and a strong finish to the financial year by SA’s Olympic Dam mine.

BHP’s chief executive officer Mike Henry has previously described the bid as a “highly compelling offer” for OZ Minerals shareholders that would provide certainty.

“The combination of BHP and OZL’s assets, skills and technical expertise provides a unique opportunity not available under separate ownership, with complementary resources including the Oak Dam exploration prospect and existing facilities within close proximity, backed by BHP’s strong balance sheet, capital discipline and commitment to sustainable development,” Henry told the ASX.

BHP works in more than 90 locations globally including throughout Australia, Chile, the United States and Canada – and owns the Olympic Dam mine in South Australia with significant copper, gold and uranium deposits.