“Nothing has been defined yet, but we can call an assembly and decide to go on strike,” Domingo Rafael Hernández García, president of labour union Sintracerromatoso, told Metal Bulletin.
“It will depend on the results of an action that we have presented to a local judge, requesting the investigation of the case as the rights of the workers have been violated by this unilateral decision”, he added.
Employees had work schedules modified to 12 hours from eight hours per day, from November 1.
While the union said the decision violated the collective employment agreement, BHP Billiton said it is in full compliance with the law.
“[The collective agreement] says that the company can make changes in the work schedule, but it has to consult with the workers’ union, and [it has not done] that”, Hernández García said.
However, a BHP spokesman said “the new roster was introduced following a consultation process with employees and unions. The asset is in full compliance with both the collective employment agreement and Colombian labour law”.
Earlier this month, Sintracerromatoso asked Colombia's Labour Ministry to intervene in the matter.
Cerro Matoso is the world's second largest producer of ferro-nickel and one of the lowest-cost producers. Located near the town of Montelíbano in northern Colombia, the asset combines a lateritic nickel ore deposit with a low-cost ferro-nickel smelter. The smelter produces high-purity, low-carbon ferro-nickel granules.
BHP said in October that it expects ferro-nickel production at Cerro Matoso to decline by 3%
to 43,000 tonnes in 2015 as a result of lower grades and recoveries.
With long-term negotiations under way, sources active in the international ferro-nickel market were watching the situation closely.