A sand mining company is asking the Minnesota Supreme Court to review an appeals ruling that upheld Winona County's ban on mining frack sand.
Minnesota Sands, which filed a petition with the high court Thursday, has argued the county's ban is unconstitutional because it singles out sand used for industrial purposes, while allowing mining for local construction uses. The sand is used to fracture shale rock in order to extract oil and natural gas.
The Winona County Board passed the ban in November 2016. The board has allowed mining to continue for construction sand, a cheaper, less pure material used on roadways and for other commercial purposes.
A Minnesota Court of Appeals rejected a lawsuit filed by Minnesota Sands and a group of landowners in July.