Jul. 31 (Bloomberg) –Workers at BHP Billiton Ltd. (BHP)'s coking-coal mines in Australia, the world's largest exporter of the steelmaking ingredient, resumed strikes today as labor unions prepare for the last two rounds of talks with management.

Employees at the Gregory and Crinum mines started shift- long stoppages today that typically last 12-hours, Stephen Smyth, a division president at the Construction, Forestry, Mining and Energy Union in Queensland, said by phone. The company plans two sets of meetings with the union in August before seeking a vote on a new work agreement, he said.

About 3,500 workers at BHP's coking-coal mines have been taking part in a series of strikes that began in June, the first in a decade at the company's Australian mines. Miners globally are stepping up demand for better pay and job security as producers such as BHP and Xstrata Plc (XTA) are forecast to report record earnings, driven by demand from China.

"We've made some slight progress, but on the big ticket items it's slow going," Smyth said. "If we're not happy with the contents of any agreement, we will tell our members that. We are considering ramping up the action if there isn't progress."

Escondida Dispute
Melbourne-based BHP also faces disputes at its operations in Escondida, the world's biggest copper mine, where a strike enters the second week, fueling concern the protest may curb global supplies of copper.

"We continue to meet and negotiate with the unions and we believe progress continues to be made," BHP spokeswoman Kelly Quirke said, without specifying the impact of the strike on the company. "We believe the actions are unnecessary, cause financial harm and do not help finalize an agreement."

Workers represented by the CFMEU, the Australian Manufacturing Workers Union and the Communications, Electrical and Plumbing Union, are seeking changes to job contracts in matters relating to job security, recruitment, use of contractors, training and development, the union has said.

The next meetings between the union and management will be on Aug. 18 and 19 with more talks scheduled a week later before a ballot, Smyth said.

BHP Billiton Mitsubishi Alliance, equally owned by BHP and Mitsubishi Development Pty., owns seven coking-coal mine operations in Queensland's Bowen Basin. It directly employs more than 4,800 people, according to its website. Almost all the coal mined at the BMA mines, with annual capacity of 58 million metric tons, is shipped overseas for steel production, it said.