Striking workers at Goderich's Compass Minerals' salt mine are trying to increase pressure on the company to get back to the negotiating table.

On Wednesday, about 300 people blocked replacement workers and members of management from entering the mine. They gathered shoulder to shoulder in front of the main entrance.

Several unmarked buses, which are meant to carry the replacement workers, remain on the site, awaiting the workers that are getting off shift.

"We are holding Compass out of the gate. We are not allowing anybody in. We will let everybody leave that worked today and wants to go home but nobody is coming in the gate or on site," said Gary Lynch, president of Unifor Local 16-0.

Striking workers are using skids to block the mine's main entrance. (Gary Lynch)

"We have members who have had enough and we are taking a stand tonight," he added.

More than 350 unionized workers have been on strike since April 27. The salt mine, located hundreds of metres beneath Lake Huron, supplies de-icing salt to cities and other customers across North America.

'We're in for the long haul'

The workers, including miners and electricians, have been trying to negotiate a new contract with the company. The top issues are job security and adequate benefits.

No talks have been planned, but Lynch hopes that will change since the blockade is set to remain for "as long as it takes."

"We're in it for the long haul. That's enough," he added.

About 300 people including striking workers and their families, congregated at the picket line on Wednesday. (Gary Lynch)

A Compass Minerals company spokesperson told CBC News that it's in the process of undertaking "enforcement measures" to aid in the continued operation of the mine.

"The current blockade by the Union and its supporters violates an existing Court Order restricting picketing activity at the site. We are disappointed that the Union is not respecting the Court Order and that our employees would put their safety and the safety of our mine at risk," a company spokesperson said in an email on Wednesday.

The company has outlined a framework for a settlement on its website. It includes a $10,000 signing bonus along with wage increases.

However, union representatives say money isn't the issue. Instead, their concerns stem from a push from management to get workers to try 12-hour shifts. The company says some moves are needed to keep the mine competitive and safe.