QSR burger chain will keep its Chattanooga, Tenn. headquarters.

Private equity firm Argonne Capital Group has purchased The Krystal Company, an 80-year-old restaurant chain specializing in burgers. Financial terms of the deal were not disclosed.

Krystal owns and franchises a total of 360 restaurants in 11 states throughout the South. The quick-serve chain opened 10 new company-owned restaurants this past year, and will continue with new store developments in 2012 and beyond, according to a company release. Officials also said the company's headquarters will remain in Chattanooga, Tenn.

Argonne's portfolio of restaurant companies includes more than 350 IHOP's, Applebee's and Stevi B's Pizza restaurants.