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Katayama K.,Hokkai Iron and Coke Corporation | Kasama S.,Nippon Steel & Sumitomo Metal Corporation
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan | Year: 2015

Decreasing NOx emission in sintering process is a key issue in steel industry. NOx emission in sintering process is decreased by coke combustion under high temperature. It has been investigated that that coating layer of CaO-Fe2O3 composition on coke surface (CF coating method) is effective for decreasing NOx. It has been considered that CaO-Fe2O3 coating layer promotes high temperature combustion and functions as catalyst for reduction of nitrogen oxide. In this study, CaO coating of coke (Lime coating coke: LCC) has been studied as simple technology for decreasing NOx. As the result, LCC has been effective like a CF coating method and it has been understood that CF melt formation on coke surface is important for decreasing NOx. About coating CaO ratio, 10% was preferable. And decrease in mixing time of LCC with iron ores (Post-mixing) was also effective. By LCC post-mixing, 17.6% NOx decreased and sinter productivity increased. Source


Ohno K.-I.,Kyushu University | Babich A.,RWTH Aachen | Mitsue J.,Kyushu University | Mitsue J.,Hokkai Iron and Coke Corporation | And 4 more authors.
ISIJ International | Year: 2012

Charcoal use instead of fossil fuel is one of the possible technologies for mitigation of CO2 emission in the steel industry because charcoal can be considered as "carbon-neutral" material. In this study, the possibility of utilization of charcoal as carbon source for carburization reaction was examined; more specifically effects of carbon crystalinity and ash in charcoal on carbon dissolution into molten iron and iron carburization reaction in iron-charcoal composite were investigated. Two kinds of experiments were carried out. One is measurement of charcoal carbon dissolution rate in iron bath. Another is observation of isothermal reaction between iron and charcoal in a composite sample. Several kinds of charcoal with relatively low ash content were applied as experimental samples. Charcoal samples were treated with several heating patterns to control their carbon crystallinity. Additionally, charcoal samples were treated with acid solutions, HCl and HF, to control the ash content in them. From these investigations, following results were revealed. Charcoal heat-treated at low temperature, 1 273 K, has advantage for carbon dissolution reaction into iron bath. Charcoal ash strongly prevents the carburization reaction between iron and carbon in the composite sample. © 2012 ISIJ. Source


Sugiura M.,Nippon Steel & Sumitomo Metal Corporation | Shinotake A.,Nippon Steel & Sumitomo Metal Corporation | Nakashima M.,Nippon Steel & Sumitomo Metal Corporation | Omoto N.,Hokkai Iron and Coke Corporation
International Journal of Thermophysics | Year: 2014

As the initial process in an integrated steel-making plant, molten iron is produced in a blast furnace. The molten iron has a temperature between 1700 K and 1900 K. The outflow stream discharged from a taphole comprises the molten iron and slag (which is a mixture of molten oxides). Monitoring of the stream temperature is important because it has information on the thermal condition inside the blast furnace. A newly developed simultaneous measurement technique for temperature and iron–slag ratio is reported. A monochromatic CCD camera with a short exposure time is used to obtain a thermal image of the rapidly moving stream. The thermal image has a marble-like pattern caused by the physical separation of the iron and slag and their different optical properties. Iron thermometry is realized by automatically detecting the peak of the iron gray-level distribution on a histogram. Meanwhile, the thermal radiance of the semitransparent slag varies as a function of the thickness. The slag temperature is calculated from the maximum gray level, presuming that the emissivity of the slag is constant at a thick slag part. The slag ratio is measured by counting the number of pixels on the histogram. A field test was carried out at an operating blast furnace. The iron temperature, slag temperature, and slag ratio were successfully measured. This multiple image measurement is expected to be the new information source for stable blast furnace operation. © 2014, Springer Science+Business Media New York. Source


Nakagawa T.,Nippon Steel & Sumitomo Metal Corporation | Kubota Y.,Nippon Steel & Sumitomo Metal Corporation | Arima T.,Nippon Steel & Sumitomo Metal Corporation | Fukuda K.,Nippon Steel & Sumitomo Metal Corporation | And 6 more authors.
ISIJ International | Year: 2011

Relationship between coking pressure and displacement of oven wall during carbonization in coke oven was investigated at Hokkai No. 6 coke oven battery (preheated-coal charging system). Determination was performed at both a superannuated oven chamber after 26 years from start and a sturdy oven chamber after a year from replacement of oven top, entire walls and oven sole. Wall displacement was observed when the internal gas pressure of plastic layer at oven center became the maximum in both oven chambers. The wall displacement increased in proportion to the internal gas pressure of plastic layer at oven center, and the displacement at superannuated oven per maximum gas pressure was larger than the one at sturdy oven. The pushing force (maximum electric current of pushing machine) greatly changed according to gas pressure of plastic layer at superannuated oven compared with the one at sturdy oven. The conclusion of this study is that the wall displacement by coking pressure greatly influences the pushing force of coke cake at superannuated oven chamber. © 2011 ISIJ. Source


Nakagawa T.,Nippon Steel & Sumitomo Metal Corporation | Kubota Y.,Nippon Steel & Sumitomo Metal Corporation | Arima T.,Nippon Steel & Sumitomo Metal Corporation | Fukuda K.,Nippon Steel & Sumitomo Metal Corporation | And 6 more authors.
Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan | Year: 2010

Relationship between coking pressure and displacement of oven wall during carbonization in coke oven was investigated at Muroran No. 6 coke oven battery (preheated-coal charging system). Determination was performed at both a superannuated oven chamber after 26 years from start and a sturdy oven chamber after a year from replacement of oven top, entire walls and oven sole. Wall displacement was observed when the internal gas pressure of plastic layer at oven center became the maximum in both oven chambers. The wall displacement increased in proportion to the internal gas pressure of plastic layer at oven center, and the displacement at superannuated oven per maximum gas pressure was larger than the one at sturdy oven. The pushing force (maximum electric current of pushing machine) greatly changed according to gas pressure of plastic layer at superannuated oven compared with the one at sturdy oven. It was concluded that the wall displacement by coking pressure greatly influences the pushing force of coke cake at superannuated oven chamber. Source

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