Smelting vs. Electrolysis
Difference Between Smelting And Electrolysis
Smelting is the final process that provides the metal in a pure enough form for machining and fabrication. This process entails heating the ore to fuse the metals together and refining it by removing the sulfur and other volatile materials and impurities. Smelting processes vary with the metal and according to the type of alloy wanted.
The blast furnace is widely used for the production of iron and as a first step in the production of steel. It also is used for preliminary copper smelting. The modern blast furnace consists of a 100-foot (30-meter)-tall tapering brick cylinder connected to three or four dome-type stoves that contain a maze of heat-absorbent brick. The brick is heated and air is blown through, heating the air. The hot air is then blown into the furnace through nozzles at the bottom at hundreds of miles per hour. Ore, coke, and limestone are dumped into the top of the furnace by skip cars that travel up a runway. As the ore drops it loses much of its oxygen, with many of the impurities either melting into slag or burning away. The blast furnace is hotter at the bottom than at the top. As the raw materials fall, they lose volume; at the hearth’s base they become fully melted.
The blast furnace can work continuously until being shut down for repairs or lack of demand. Every four or five hours the furnace is tapped. Molten iron flows out of a tap hole into a ladle that keeps the iron molten while it is delivered to various steel departments or poured into molds for cooling. The molds create rectangular lumps called “pigs,” thus creating “pig iron,” sold to steel mills that do not produce their own iron. The iron created in a blast furnace is not pure but contains high concentrations of carbon, absorbed from the burning coke, and other impurities. To make the product into steel, the Bessemer process, the open hearth furnace, the electric furnace, the oxygen furnace, or the vacuum process are used.
Electrolysis is used to separate metals from ores when the metallic compound is in a solution or is melted. It is also used to produce pure metal from metal that contains impurities. Both copper and aluminum are produced by electrolysis.
When an electric current is passed through the liquid, the metal is deposited at the cathode, the negatively charged pole.