Vale said in a June 1 securities filing it will suspend operations at its nickel mine in Sudbury, Ontario, Canada, after a proposed 5-year contract was rejected by the United Steelworkers.

United Steelworkers (USW) Local 6500, representing roughly 2,450 production and maintenance employees in Sudbury, voted to reject the company’s offer despite the unanimous endorsement of that deal by the union bargaining committee.

USW Local 6200, representing 100 production and maintenance employees in Port Colborne, voted to ratify the agreement.

Vale said it has implemented contingency plans to preserve the integrity and safety its operations.

The company said the offer, and the union bargaining team’s endorsement of that offer, reflected months of hard work and commitment on both sides and a sincere demonstration to favorably conclude negotiations. Vale said it is committed to the long-term sustainability of its base metals business and its Ontario operations. The company will continue discussions with USW in the hopes that both sides can find a path towards a ratified agreement in the near-term.