Kritza is a loose lump of softened spongy iron mixed with slag and particles of unburned coal , formed during the melting of iron ore at low temperatures (up to 1300 ° C). The name comes from the old Russian "krech" - a blacksmith [1] . Also called krytsu cheesy iron [2] .
Content
History
In ancient times, iron was obtained by heating iron ores mixed with charcoal in pits located below the surface of the earth and often surrounded by a small shaft of clay and small stones to reduce heat loss. The first metallurgical unit specifically designed for the reduction of iron ores was a low (1–1.5 m high) cheese-forge . Under the influence of hot reducing gas, a crust formed in it, since the temperature in the furnace did not exceed 1300 ° C and was insufficient for the formation of cast iron [3] [1] .
Subsequently, kritz was obtained in more complex furnaces - shtukofen , Catalan forges .
After 4–5 hours of continuous operation of the furnace, the white-hot mite was extracted with a tick with a tick through a gap in the front wall of the furnace along with part of the slag and pieces of coal. The metal was compacted with a wooden hammer, large krits were chopped with an ax into 2–4 parts and forged with a blacksmith's hammer to remove slag from the pores (its initial amount was 4–6% by weight). The bulk of the slag was squeezed out of the metal, and the remaining slag in an amount of 1–2% was located in the form of threads interwoven with metal fibers. Before the next smelting, the front wall of the hearth was repaired, a new nozzle was inserted, the cooled masonry was heated by burning a portion of charcoal, after which the production of a new kritz started. Depending on the size of the hearth and the intensity of the supply of blast, 10–80 kg of metal was obtained per melting, and the number of produced coal per day reached 3-4.
In Catalan forge, the cricket was extracted with ticks through the top, using crowbars ́ as levers. To facilitate the work, one of the side walls of the hearth was made lower than the other. The weight of the crits reached 100–150 kg; during the year they produced up to a thousand crits [4] . The hot kritz was sealed with a mechanical hammer driven by a water wheel . [2]
Theories of Education Critics
The most common theory of obtaining kritza is that iron ore was reduced to solid metal in the form of a porous, pasty, low-carbon mass, through which viscous glandular slag penetrated, melting well at temperatures above 1200 ° C. As a result, porous iron formed a fairly dense ring and was usually not saturated with carbon. Only in some places were carburized zones formed. The aim of the smelting was to obtain as soft as possible (low-carbon) malleable metal.
Some researchers believe that during cheese-smelting in the furnace zones, where the temperature was 800–1200 ° С, the iron particles were first carbonized and then melted in the form of cast iron. However, then the reoxidation of carbon and metal occurred in the tuyere zone of the furnace, the temperature in which exceeded 1400 ° C. A number of authors believe that in both of the above theories there is some truth, since, despite the small size of the first raw-furnace furnaces or thanks to them, and possibly depending on the method of preparation and loading of the charge into the furnace in both of its zones, both processes could take place. Therefore, products of cheese production could contain highly carbonized metal, and even particles of cast iron . There is also a point of view according to which the process of obtaining kritzas could be two-stage. In this case, a partially reduced or metallized agglomerate was obtained during the first stage of ore smelting. In the second stage, this agglomerate was remelted to obtain a dense iron cricket or cast iron [5] .
See also
- History of iron production and use
- Domain process
- Blast furnace
- Catalan horn
- Cheese oven
Notes
- ↑ 1 2 Babarykin, 2009 , p. 6.
- ↑ 1 2 Babarykin, 2009 , p. eight.
- ↑ Wegman, 2004 , p. thirty.
- ↑ Wegman, 2004 , p. 31.
- ↑ Karabasov, 2014 , p. 48-49.
Literature
- Babarykin NN Theory and technology of the domain process. - Magnitogorsk: GOU VPO "MSTU", 2009. - P. 15. - 257 p.
- Wegman E.F. , Zherebin B.N., Pokhvisnev A.N. et al. Iron metallurgy. - Moscow: Academic book, 2004 .-- 774 p. - ISBN 5-94628-120-8 .
- Karabasov Yu.S., Chernousov P.I., Korotchenko N.A., Golubev O.V. Metallurgy and time: an encyclopedia. T. 1. The basics of the profession. The ancient world and the early Middle Ages. - Moscow: Publishing. MISiS House, 2014 .-- 224 p. - ISBN 978-5-87623-536-7 .