Southwest Environmental Alliance protesters gathered in front of city hall to call on Mayor Brandon Johnson to delay issuing a permit for the business.
The state sued Sims Metal Management a few years ago for allegedly failing to control emissions from its facility.
Sims said it has since put air monitors around the business to reduce toxic emissions.
Now, the company is seeking a permit to open a business in Pilsen, a historically Latino neighborhood.
Protesters called the company a "serial polluter." They added that operations would put Pilsen residents at health risk in a community already over-burdened by pollution.
"Sims has a horrible history and the only one that can stop this is the mayor and CDPH. Deny the permit," Southwest Environmental Alliance Chair Theresa McNamara said.
"They haven't fully considered the bad track record that Sims has and the numerous violations of state and federal and local law," Brian McKeon said. "And that's what we want the mayor to put a stop to this process so that these things can be fully considered before issuing a permit."
They asked Mayor Brandon Johnson to delay granting Sims a permit and reexamine their application.
They want the business to prove they will reduce harmful air emissions before opening the new facility.