NORTH BRANCH — A silica sand processing plant in eastern Minnesota has agreed to pay a fine for air quality and noise violations.

The Minnesota Pollution Control Agency levied a fine of $85,000 for Tiller Corp. which has been operating a processing and shipment center in Chisago County for nearly two years. Tiller mines silica sand in western Wisconsin and transports it to North Branch for processing and shipping by rail.

The agency says Tiller exceeded limits for particulate matter, carbon monoxide, volatile organic compounds and sulfur dioxide. It had 25 emissions violations as well as four noise violations.

Tiller spokesman Mike Caron says the company made changes nearly a year ago to address the state’s concerns. It stopped operating certain equipment at night and eliminated its use of fuels that caused emissions violations.