Flint Hills Resources will begin idling its No. 1 crude processing unit at its North Pole refinery.
The company said that challenging economics and rising crude prices have forced the move, and will mean the layoff of 35 to 40 workers over the next five months.
Flint Hills will continue operating its remaining No. 2 crude unit to produce jet fuel, gasoline, asphalt and some specialty fuels.
The refinery previously idled its No. 3 crude unit.
The affected employees will have an opportunity to apply for other positions within the company, or will receive severance packages.
The current economics of refining is challenging for refineries across the world.
Over the last several years 16 refineries in North America and Europe have shut down.