IRON -- PRODUCT OF THE BLAST FURNACE

[Music] the process of reducing iron ore to pig iron or cast iron is called smelting iron ore is smelted in a huge cylindrical tower called a blast furnace here is a blast furnace and the stoves for heating air used in the furnace compare the size of the furnace with the railroad cars in the foreground a blast furnace operates continuously day and night year after year stopping only when it is necessary to replace the brick lining of the furnace this diagram will help us to understand what happens inside the blast furnace raw materials brought to the top of the furnace by a Skip car are dumped into the furnace in alternate layers a layer of iron or a layer of coke a layer of limestone and so on three large brick blind stoves on the right are used to heat air which is blown into the furnace at the bottom around the base of the furnace is a huge pipe called the bus'll pipe which carries hot air from the stoves to the base of the furnace hot air is blown into the furnace through nozzles or blow pipes this blast of hot air makes the coke burn at high temperatures forming carbon monoxide this superheated gas rises through the blast furnace charge separating oxygen from the iron or high temperatures melt the iron which collects at the bottom of the furnace the limestone also melts and combines with impurities in the ore forming slag which floats on the top of the molten iron most important raw material used in the blast furnace is iron ore brought to the furnace in huge quantities by boat or railcar here cars containing iron ore are arriving at the raw materials yard they caused great amounts of war and other materials are handled each day automatic machinery is used to unload raw materials and transport them to the blast furnace in this building the ore cars are emptied by turning the entire car upside down in a special dumping machine the or falls out of the rail cars into hoppers and then to underground conveyor belt on the conveyor belt the ore is carried to a giant crushing machine which crushes large chunks of or to a uniform size the ore is stacked in neat triangular shaped piles by this huge traveling stacking machine the main purpose of the neat stacking is not for the sake of appearance but to thoroughly blend the ore to make it all of uniform grade blast furnaces maintain large stockpiles of ore so the flow of or to the furnace is never interrupted from another stockpile of or a reclaiming machine takes or off the bottom of the pile for immediate use in the blast furnace a large triangular rake move slowly back and forth across the stockpile cutting into the orb heavy steel blades push the ore on to another moving conveyor belt which delivers the crushed and blended or direct to storage hoppers near the blast furnace second most important material used in the blast furnace is coke made by baking coal in closed ovens bituminous or soft coal is brought to the coke ovens in huge quantities rail cars loaded with coal are brought to this unloading hopper when the car is directly above the hopper workmen release doors in the bottom of the cars spilling the coal onto an underground conveyor belt again by rapidly moving conveyor belt the coal is moved to stockpiles for future use large stockpiles of coal must be maintained to ensure a continuous supply of coke for the blast furnace from one of several stockpiles coal is loaded onto another conveyor belt which will carry it to coal crushing machinery when the coal goes into coke ovens it must be of uniform and small size efficient and economical handling of such huge quantities of raw materials is made possible by the use of conveyor belts a large travelling hopper known as a Larry car delivers the crushed and screened coal to a rectangular coke oven through openings in the top of the oven when the oven is full it is sealed except for collector pipes which carried by product gases and other matter to the by-product plant besides producing coke for the blast furnace the coke ovens produce many valuable byproducts after heating at high temperatures for about 18 hours the fiery coke is pushed out of one end of the coke oven and falls into a special hot car within the coke oven the coke is sealed airtight and does not burn but as soon as it is pushed out of the coke oven and makes contact with oxygen in the air it bursts into flame to keep it from burning itself out the coke must be cooled by spraying it with water this operation is called quenching here the hot car containing burning coke is entering the quenching tower where four to six thousand gallons of water will be dropped on the hot coke to cool it when the water touches the hot coke some of it is changed to steam which rises to the top of the quenching tower then the steaming coke car moves back and dumps its load of quenched coke onto a coke Wharf along the track continuous conveyor belts are again used to carry coke to storage piles near the blast furnace third most important material used in the blast furnace is limestone usually obtained from surface quarries and brought to the blast furnace by ship or railcar here crushed limestone is arriving at the raw material yard of the blast furnace the limestone is sprayed with water to settle dust and dumped in the same way as the iron ore was dumped onto a conveyor belt which carries it rapidly to large storage piles these special scale cars weigh up the correct amount of each raw material according to an accurate scale built into the cars by exact analysis and accurate weighing of the raw materials the operator of a blast furnace can produce pig iron exactly as required for making steel after weighing raw material is dumped into a skip car which carries it to the top of the blast furnace here a full car is going up and an empty car is going down the raw materials are not mixed until they reach the inside of the blast furnace every five or six hours the blast furnace is cast to remove the molten iron and slag the workmen who opened the cast holes where heavy fireproof clothing to protect themselves when the furnace is cast about 250 tons of liquid iron flow from the great furnace but for each ton I earn that comes out of the furnace one on one half tons of iron or one ton of coke one half ton of limestone and three and one half tons of air went into the fiery furnace here molten iron flows in a seemingly endless stream directly into special hot metal cars called torpedo ladle cards one of these cars can carry about one half of the molten iron removed from the furnace at each five hour casting when the casting of the furnace is completed a large mud gun seals the cast hole until time to cast the furnace again this mud gun is controlled by motors so that no workman needs to get near the flaming molten iron now the torpedo ladle car fully loaded with hot molten iron is ready to leave the blast furnace and travel to the nearby open heart furnaces very little of the molten iron is cast into pigs which give it the name pig iron most of it goes directly into the making of steel in open hearth furnaces thus iron ore coke and limestone put into the blast furnace in solid form have been transformed by the magic of modern industry into a liquid metal of nearly pure iron which will next be made into steel a metal more important in our modern civilization than any other material