Vale will begin a partial restart of its Sudbury, Ontario, operations this week, a company spokesman said on Wednesday, as signs emerged that workers were becoming frustrated with the 2-1/2 month strike at the site.

The Brazilian mining company will restart its Clarabelle mill on Thursday for an initial 48-hour period to work through stockpiled ore, said company spokesman Cory McPhee.

Workers will begin mining copper and precious metals from the Coleman 153 and Garson Ramp orebodies next week, and Clarabelle will then resume to process the ore from those mines as well as ore from local mines owned by FNX Mining.

The mill operates as feed is available. We're still doing preparatory work at (Coleman and Garson), said McPhee.

Vale normally operates a total of six mines in Sudbury, as well as milling, smelting and refining facilities. It took over the operations when it bought Canada's Inco in 2006.

The mill and mines will be run by 1,200 workers from outside the main bargaining unit that has been on strike since July 13.

More than 3,000 workers represented by the United Steelworkers union are off the job in Sudbury, while a few hundred are on strike at the company's Port Colborne, Ontario, operations and at the Voisey's Bay mine in the province of Newfoundland and Labrador.


McPhee said no talks are scheduled between the two sides.

However, tensions appear to be building between workers on the picket lines and the company.

McPhee said Vale had fired three strikers due to threats of violence made on the picket line.

In a separate but potentially more serious incident, he said, the company discovered a blocking device placed on a connecting rail line that could have derailed a train.

There was a block put on the railway tracks that was discovered by the operators of the train and removed, said McPhee. We don't know who did that.

Vale also went to court last week to obtain an injunction to ensure steady access to its facilities after vehicles faced delays outside the scope of allowed limits.

Spokesmen for the union were not immediately available for comment.

Vale's Sudbury operations produced 85,300 tonnes of contained nickel last year, while Voisey's Bay produced 77,500 tonnes.

Analysts say the strike has helped support nickel prices, although the metal is still trading at just a fraction of levels hit before the recession ate into demand last year.

Three-month nickel MNI3 was at $17,800 a tonne on Wednesday.

(Reporting by Cameron French; editing by Rob Wilson)