Workers in this unit group operate metal smelting, converting and refining furnaces. Their functions include: operating blast furnaces to smelt ores for production of ferrous or non-ferrous metals; operating furnaces to convert or refine pigiron or scrap-metal to produce steel; operating furnaces to convert or refine non-ferrous metals; performing related tasks. Workers who operate furnaces to melt metal for casting or reheat metal for forging, pressing or rolling are classified in unit group 7-23.