Unifor wants Compass Minerals to delay a massive round of layoffs and review whether proper procedures were followed.
Unifor says the 48 workers were handed their notice at the gate as they arrived for work February 21.
"Being laid off is a major event in any family's life," says Unifor National President Jerry Dias. "We have serious concerns about the way Compass has acted, and we're calling on the employer to respect the collective agreement and their obligations under the law."
Unifor suggests workers are being asked to accept a severance package, which cancels their right to a recall if production increases.
"Laying off 10% of the bargaining unit two weeks before bargaining is a very aggressive move," says Glenn Sonier, the Unifor National representative responsible for Local 16-O. "Compass is acting like an employer itching for major job action."
Local 16-O has given notice to bargaining for March 5 and 6 and has filed for conciliation.