By Paul Garvey

June 27, 2017 - Glencore has just 24 hours to pull a rabbit out of its hat, or risk tarnishing its reputation as the shrewdest dealmaker in the mining business.

The Switzerland-based heavyweight had its eleventh-hour $US2.675 billion ($3.5bn) bid for Rio Tinto’s New South Wales coal business Coal & Allied rebuffed on Monday night and Rio’s London-based shareholders last night voted to endorse the sale of the business to the China-backed Yancoal Australia.

Rio will be bound to completing the deal with Yancoal when its Australia-based shareholders give their consent to the transaction at a shareholder meeting in Sydney tomorrow, leaving Glencore a narrow window to produce a further revised bid that would compel Rio to postpone the meeting. Glencore has long harboured a desire for the Coal & Allied ­operations, which adjoin some of Glencore’s mines in New South Wales.

Analysts have estimated that combining the respective Hunter Valley operations could generate up to $1bn in operating synergies for the company.

But the Ivan Glasenberg-led group appears to have uncharacteristically miscalculated in its ­approach to the sales process.

Rio first put the assets up for sale in 2015, but was unable to ­secure an appropriately attractive offer and Glencore then appeared to misread both the interest and appetite of Yancoal when the sale process cranked back up again last year.

Yancoal, with an initial $US2.45bn bid, was announced as the winning bidder in January, confounding those who thought its debt burden would inhibit its ability to outbid Glencore.

The Swiss group emerged in the past three weeks with two counter offers, but has been unable to shake Rio’s ­endorsement of a deal with Yancoal.

The Chinese group has twice improved the terms of its offer in response to Glencore’s rival bids, but has been able to limit the damage thanks to its twin advantages of incumbency and time.

In winning the initial auction process in January, Yancoal also picked up the right to match any eventual higher counter offer.

It also picked up a crucial head start on the regulatory process, giving its offer greater certainty of approval and a shorter time­frame to settlement.

Glencore tried to address those issues in its most recent bid, offering a $US250 million deposit that would not be refundable if its offer was blocked by regulators as well as a bonus of $US25m a month if its deal dragged on, but it has not been enough for Rio to abandon Yancoal.