ТЕМІР ҚҰЮ ПРОЦЕСІ: ҚОҒЫЗДАЛҒАН ТЕМІРДІ ТАЗАРТУ ӘДІСІ

Step in the manufacture of iron
an obsolete method for purifying pig iron

Puddling is the process of converting pig iron to bar (wrought) iron in a coal fired reverberatory furnace. It was developed in England during the 1780s. The molten pig iron was stirred in a reverberatory furnace, in an oxidizing environment to burn the carbon, resulting in wrought iron. It was one of the most important processes for making the first appreciable volumes of valuable and useful bar iron (malleable wrought iron) without the use of charcoal. Eventually, the furnace would be used to make small quantities of specialty steels. Though it was not the first process to produce bar iron without charcoal, puddling was by far the most successful, and replaced the earlier potting and stamping processes, as well as the much older charcoal finery and bloomery processes. This enabled a great expansion of iron production to take place in Great Britain, and shortly afterwards, in North America. That expansion constitutes the beginnings of the Industrial Revolution so far as the iron industry is concerned. Most 19th century applications of wrought iron, including the Eiffel Tower, bridges, and the original framework of the Statue of Liberty, used puddled iron.

Modern puddling was one of several processes developed in the second half of the 18th century in Great Britain for producing bar iron from pig iron without the use of charcoal. It gradually replaced the earlier charcoal fueled process, conducted in a finery forge.

Pig iron contains much free carbon and is brittle. Before it can be used, and before it can be worked by a blacksmith, it must be converted to a more malleable form as bar iron, the early stage of wrought iron. Abraham Darby's successful use of coke for his blast furnace at Coalbrookdale in 1709 reduced the price of iron, but this coke fuelled pig iron was not initially accepted as it could not be converted to bar iron by the existing methods. Sulfur impurities from the coke made it 'red short', or brittle when heated, and so the finery process was unworkable for it. It was not until around 1750, when steam powered blowing increased furnace temperatures enough to allow sufficient lime to be added to remove the sulfur, that coke pig iron began to be adopted. Also, better processes were developed to refine it.

In the late 1840s, the German chemist de developed a modification of the puddling process to produce not iron but steel at the Haspe Iron Works in Hagen; it was subsequently commercialized in Germany, France and the UK in the 1850s, and puddled steel was the main raw material for Krupp cast steel even in the 1870s. Before the development of the basic refractory lining (with magnesium oxide, MgO) and the wide scale adoption of the Gilchrist–Thomas process ca. 1880 it complemented acidic Bessemer converters (with a refractory material made of |SiO2|link=silica) and open hearths because unlike them, the puddling furnace could utilize phosphorous ores abundant in Continental Europe.

The puddling furnace is a metalmaking technology used to create wrought iron or steel from the pig iron produced in a blast furnace. The furnace is constructed to pull the hot air over the iron without the fuel coming into direct contact with the iron, a system generally known as a reverberatory furnace or open hearth furnace. The major advantage of this system is keeping the impurities of the fuel separated from the charge. The hearth is where the iron is charged, melted and puddled. The hearth's shape is usually elliptical; in length and wide. If the furnace is designed to puddle white iron then the hearth depth is never more than If the furnace is designed to boil gray iron then the average hearth depth is Due to the great heat required to melt the charge the grate had to be cooled, lest it melt with the charge. This was done by running a constant flow of cool air on it, or by throwing water on the bottom of the grate. The fireplace, where the fuel is burned, used a cast iron grate which varied in size depending on the fuel used. If bituminous coal is used then an average grate size is and is loaded with of coal. If anthracite coal is used then the grate is and is loaded with of coal. A double puddling furnace is similar to a single puddling furnace, with the major difference being there are two work doors allowing two puddlers to work the furnace at the same time. The biggest advantage of this setup is that it produces twice as much wrought iron. It is also more economical and fuel efficient compared to a single furnace.