Taken a bit of a liberty here as strictly speaking they are not smelters but an important part of the the iron industry in Wyoming and Utah.
Briefly.
Built by Moses Byrne in 1869 to supply charcoal for the iron smelting industry in Utah, these conical limestone kilns measure 30 feet across and 30 feet high. Only three of the original 40 kilns remain. It was estimated that during 1873, the kilns could produce 100,000 bushels of charcoal. Most of the charcoal was sent to Utah on the UP railroad. Wood burned in the kilns came from the nearby Uinta Mountains. The ghost of Piedmont is nearby, as is the Byrne family cemetery.