Molten Marvels – The Evolution of Ironworks
Long before bridges, I-beams, and skyscrapers, blazing stars fused atoms to make iron and carbon. Those materials eventually made their way to Earth, 鉄製品 オーダーメイド where metalworkers refined them into wrought and cast iron.
As Europe stretched its power, the demand for steel exploded. But the traditional crucible steelmaking process was too costly to keep up. The Ore
The men of the Iron Mountain Company were no slouches in the matter of business. They sank a shaft on the little mountain, trundled chunks of iron ore down the sides of it on tramways and into railroad cars that ran up and down the rude steps cut in the side of the hill. The cars were loaded and emptied by gravity alone, for one load coming down pulled the empty one up; and in this way over a thousand tons a day left the little mountain for the furnaces.
The smelters had not yet perfected a method for making steel, but they had discovered something very important. Wrought iron had less carbon than cast iron, but it still lacked the tensile strength of true steel. They had not yet figured out how to lower the carbon content of the iron to make it truly strong and hard, and when they did, the discovery would change history.
Early metalworking was primarily forging, and only when this failed to produce a desired result were hand-tools used. This system was inefficient, laborious and unreliable. It took a great deal of time to produce a small amount of metal, and a large amount of slag, or waste material, was generated. The slag was a nuisance to dispose of, but its calcium oxide content made it an excellent fertiliser.
Davis skillfully weaves lifelike passages of exposition among her characters’ thoughts and conversations, making it easy for the reader to feel like a fly on the wall in the little smeltery. She describes the squalid conditions of the workroom, the crudeness and tawdry character of the gangs of workers that toiled at the furnaces, the smelting methods employed and the products produced.
The gentlemen of the Iron Mountain Company had many theories about how this little mountain of ore was formed. Certainly, the conditions in which it existed were unique, and it was difficult to compare them with anything that had been seen before. The men had a habit of discussing the formations around the little mountain, and the superintendent seemed to be always listening with an eager ear. The Blast Furnace
Until the industrial revolution began, crude iron was transformed into metal in tower-like structures called blast furnaces. These were charged with iron ore along with coke and, often, limestone as well. Under a powerful blast of hot air the coke burns fiercely, driving out molten iron from the ore and limestone to form a pasty mass known as slag. The slag, being lighter than the iron, collects in a layer on top of the molten iron. Periodically the blast furnace is tapped, and the two products are run out of the hearth through great ladles into the huge slag-heaps that are a prominent feature of ironworking districts.
The smelting process had to be improved and modernized. For example, the old methods of iron smelting did not reliably remove phosphorus, a toxic byproduct of the smelting process. Phosphorus contaminated the steel and caused it to become brittle. The Bessemer converter solved this problem by blasting pure oxygen into the molten iron, rather than the traditional mixture of air and carbon dioxide.
This method also allowed for greater control of the smelting process, which yielded much higher quality steel. In addition, the Bessemer converter reduced the amount of slag produced by about half. Today, the Carrie Furnaces National Historic Landmark is the only remaining blast furnace in Pennsylvania.
Visitors to the site can see the slag heaps and the blown-out furnace doors through a glass window in a sandstone building. The museum is open from April through October, and is closed on Thanksgiving, Christmas and New Year's Day. Sculptures by Bradford Mumpower and a rope sculpture by Mark Davis adorn the grounds, and the slag piles are carved into shapes that reflect the history of the place. The story of steel begins long before bridges and I-beams. Billions of years ago, blazing stars fused atoms into elements like iron and carbon. Then, over countless cosmic explosions and rebirths, the elements were drawn together to form our planet's internal structure. Now, the same elemental dance between heat and pressure continues to shape the world around us. The Ladle
Iron innovation came just in time for a Western world at war, and the invention of cannons and firearms generated an insatiable demand for metal. Pig iron could be poured right into gun barrel and cannon moulds, and Europe started pumping out weapons like never before.
The hot liquid iron from the blast furnace is poured into a huge tank called a mixer, which is mounted on rollers so it can be tilted to fill ladles in which the molten iron is conveyed to the steel furnaces. The operation of mixing has the great advantage of helping to reduce the silicon and sulphur content of the metal. The mixture is also stirred, which makes it easier to melt the carbon from the slag that has settled on top of the molten cast iron.
It is not cooled, however, because that would involve wasteful loss of heat. A sample is drawn from the molten stuff, usually a casting made from some of the cast iron, to determine its carbon content, and if necessary to test for other impurities. The sample is then drawn off into a ladle and passed, usually by a locomotive along a railway line, to the steel plant which is probably closely adjacent.
In older ironworks whose business was to produce cast pig iron for sale as such, the processing stops here, but in modern steelworks the molten iron passes directly from the mixers into the steel furnaces. A plug is closed in the bottom of the ladle, which is then run along a row of steel cast-iron moulds and filled with molten steel as directed by an operator on a platform. The plug is then opened in the next mould, and so on until the castings are all made.
In Life in the Iron Mills, Davis threads lifelike passages of exposition between the conversations and thoughts of characters working in an industrial factory. The owners and managers tour the facility, but they do not seem to recognize workers such as Hugh or Deborah as more than parts of their giant machines. They may admire the sculptures the workers have forged from korl, but they cannot understand how and why such sublime statues can be made out of discarded scraps of raw material. The Ingot-Moulds
The pig iron cast from the furnaces is run into channels cut in a bed of sand which on cooling take the form of the familiar stubby pigs. At the modern works where pig iron is made for sale as such this casting process is often replaced by metal moulds arranged in an endless moving band. The molten steel is drawn off at intervals from the ladle and put into these moulds. The plug at the bottom of each is closed as each is filled, and the steel remains in the moulds only a short time before it is transferred to another ladle.
The string of ingots that have been teemed is now lowered into fiery apertures below floor-level, known as soaking pits. Here each ingot is'soaked' in heat for a brief period so that it will be at an even temperature right through when rolling begins. The soaking allows any oxides or impurities to be dissolved away, and the result is a high-grade raw material for rolling into the shaped products that we use in our everyday lives.
A new smelting method was invented in India around 400 BC. The Indians discovered that if they inserted small bits of wrought iron and charcoal into clay receptacles called crucibles, melted the smelted iron in it, then mixed in the carbon from the charcoal, they could produce steel – a new, stronger metal than either wrought or cast iron.
In the 13th and 14th centuries this new metal revolutionised the world of war. Cannons and gun barrels needed a lot of it, and Europe's factories began pumping them out like never before.
The next stage is to make the steel into the shapes and sizes that we need. The steel is brought from the converters to a series of ingot-moulds by a travelling crane carried in a non-tilting ladle. It is a very large flask, pivoted on one end so that its mouth can be directed to any of the rows of moulds, and an operator on a platform opens and closes a plug at the bottom as each of the moulds is filled.