A system for melting a pelleted charge material which comprises one or more of iron pellets, direct reduced iron pellets, and hot briquetted iron pellets, for producing pig iron comprising: a continuous long rectangular furnace having a feed end configured to receive a solid pelleted charge material and a discharge end opposite the feed end configured to discharge a molten charge material and a slag; a conveyor configured to feed the pelleted charge material into the feed end of the furnace; at least one oxy-fuel burner positioned to direct heat into a melting zone near the feed end to heat and at least partially melt the pelleted charge material to form the molten charge material and slag, wherein the oxy-fuel burner is configured to use an oxidant having at least 70% molecular oxygen; and at least one flue for exhausting burner combustion products from the furnace; and a stirring mechanism for stirring the molten charge material and facilitating mixing of the pelleted charge material into the molten charge material in the melting zone, wherein the stirring mechanism is selected from the group consisting of: one or more bottom stir nozzles for injecting an inert gas through the bottom of the furnace, and an electromechanical stirring device, wherein the furnace has a length and a width, wherein the charge material moves horizontally in a lengthwise direction from the feed end to the discharge end, and wherein the at least one burner is positioned near the feed end, the length being at least twice the width; and wherein at least a portion of the bottom is sloped downward from the feed end toward the discharge end to enable gravity to assist in moving charge material from the feed end to the discharge end. a continuous long rectangular furnace having a feed end configured to receive a solid pelleted charge material and a discharge end opposite the feed end configured to discharge a molten charge material and a slag; a conveyor configured to feed the pelleted charge material into the feed end of the furnace; at least one oxy-fuel burner positioned to direct heat into a melting zone near the feed end to heat and at least partially melt the pelleted charge material to form the molten charge material and slag, wherein the oxy-fuel burner is configured to use an oxidant having at least 70% molecular oxygen; and at least one flue for exhausting burner combustion products from the furnace; and a stirring mechanism for stirring the molten charge material and facilitating mixing of the pelleted charge material into the molten charge material in the melting zone, wherein the stirring mechanism is selected from the group consisting of: one or more bottom stir nozzles for injecting an inert gas through the bottom of the furnace, and an electromechanical stirring device, wherein the furnace has a length and a width, wherein the charge material moves horizontally in a lengthwise direction from the feed end to the discharge end, and wherein the at least one burner is positioned near the feed end, the length being at least twice the width; and wherein at least a portion of the bottom is sloped downward from the feed end toward the discharge end to enable gravity to assist in moving charge material from the feed end to the discharge end.