Scrap-melting Operation by Shaft Furnace using all Blast Furnace Coke and Steel Scrap

Abstract

In the scrap-melting operation of shaft furnaces, an operation technology with use of 100% small size blast furnace coke for solid fuel instead of typically utilizing foundry coke has been established. An operation technology with use of 100% steel scrap without using return scrap containing 3-4 % carbon for ferrous raw material, and 70% or more of steel scrap consists of shredder scrap, has been established as well. This technology was fi rst developed with one-stage tuyere operations using only lower tuyeres. Next two-stage tuyere operations using lower and upper tuyeres has been developed to explore more effi cient operation. In the two-stage tuyere operation, the number of pipes, the diameter, and the protruding length of the upper tuyeres were examined as parameters, an operation technology with high effi ciency was established, which enabled us to achieve high productivity and low coke ratio.

Ironmaking Technology for the Last 100 Years: Deployment to Advanced Technologies from Introduction of Technological Know-how, and Evolution to Next-generation Process

“…Development of a number of recycling technologies went forward, including processing of waste plastics in blast furnaces 44) and coke ovens, 45) dezincification of dust with high Zn contents using rotary hearth furnaces (RHF) 46) and use of the generated reduced iron in the blast furnace, and dust and scrap processing. 50,51) From 2000 onward, the trend in blast furnace improvements was toward expansion of furnace capacity, and by 2013, 13 of the 27 blast furnaces in Japan had been converted to 5 000 m 3 class large blast furnaces. Blast furnace service life was extended through the development of carbon blocks, 53,55) introduction of Cu staves, 53,56) and similar activities.…”

“…The two-stage tuyere smelting reduction furnace STAR (STainless steel Advanced Reactor) 47) at Kawasaki Steel Chiba Works and the multi-function melting furnace MFMF (Multi-Function Melting Furnace) 50,51,211) at Nippon Steel Nagoya Works are examples of shaft furnaces which employ a coke packed bed.…”

“…In 100% steel scrap operation with blast furnace coke, low coke rate operation was achieved at a tapping rate of 22 t/d/m 3 and CR of about 190 kg/thm by utilizing two-stage blowing. 211) Table 3 shows a classification of the direct reduction processes which are currently under development or in operation worldwide by furnace type, temperature, and reducing agent. 212) Shaft furnace processes for gas reduction of fired pellets, such as the MIDREX process, are predominant; however, depending on the reducing agent supply, rotary kiln processes, in which reduction is performed in a rotary kiln by carbon outside of the agglomerate, are also used.…”

“…In response to subsequent economic and environmental trends, the steel industry has taken on the role of a world leader 4) in driving technological development in various fields of the steel production process, from environment-friendly technologies such as technologies for using low-cost raw materials and reducing agents [5][6][7][8][9][10][11][12][13][14][15] (including low Si operation technology [16][17][18][19][20][21][22][23][24][25][26][27] and high rate pulverized coal injection [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] ), recycling of waste plastics, 44,45) and processing of ironmaking dust [46][47][48][49][50][51] ...…”