Production method of pig iron

Patent metadata

Field	Value
Publication number	US-2023313328-A1
Application number	US-202018042876-A
Country	US
Kind code	A1
Filing date	Sep 29, 2020
Priority date	Sep 3, 2020
Publication date	Oct 5, 2023
Grant date	—

Abstract

A production method of pig iron using a blast furnace with a tuyere includes: charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace; and reducing and melting the iron ore material in the charged first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere, in which: an aggregate for letting through the hot air to a central portion of the blast furnace is blended into the first layer; and the aggregate contains a reduced iron molded product obtained through compression molding of reduced iron.

First claim

1 . A production method of pig iron using a blast furnace with a tuyere, the production method comprising:
charging a first layer containing an iron ore material and a second layer containing coke alternately in the blast furnace; and reducing and melting the iron ore material in the charged first layer while injecting an auxiliary reductant into the blast furnace by hot air blown from the tuyere, wherein: an aggregate for letting through the hot air to a central portion of the blast furnace is blended into the first layer; and the aggregate contains a reduced iron molded product obtained through compression molding of reduced iron.

2 . The production method of pig iron according to claim 1 , wherein:
a charged rate of the reduced iron molded product is greater than or equal to 100 kg per 1 ton of the pig iron, a ratio of an average grain size of the reduced iron molded product to an average grain size of the iron ore material is greater than or equal to 1.3; and a gas permeability resistance index of the reduced iron molded product after a tumbler rotation test is less than or equal to 0.1.

3 . The production method of pig iron according to claim 1 , wherein basicity of the reduced iron molded product is greater than or equal to 0.9.

4 . The production method of pig iron according to claim 1 , wherein: the reduced iron molded product contains aluminum oxide; and
a content of the aluminum oxide in the reduced iron molded product is less than or equal to 1.5% by mass.

5 . The production method of pig iron according to claim 1 , wherein a content of the reduced iron molded product in the first layer is less than or equal to 30% by mass.

6 . The production method of pig iron according to claim 5 , wherein the iron ore material contains iron ore pellet, of which a porosity resulting from large open pores having a pore size of greater than or equal to 4 μm is greater than or equal to 21%.

7 . The production method of pig iron according to claim 5 , further comprising charging a mixture of the coke and the reduced iron molded product to the central portion of the blast furnace, wherein:
in the reduced iron molded product in the mixture, a proportion of the reduced iron molded product having a grain size of greater than or equal to 5 mm is greater than or equal to 90% by mass; and a content of the reduced iron molded product in the mixture is less than or equal to 75% by mass.

8 . The production method of pig iron according to claim 5 , further comprising finely pulverizing powder derived from the reduced iron molded product and coal, wherein
fine powder obtained by the finely pulverizing is comprised as the auxiliary reductant.

Assignees

• Kobe Steel Ltd

Inventors

• Kasai Akito
• YAKEYA Masahiro

Classifications

• C21B3/02

  by applying additives, e.g. fluxing agents · CPC title

• C21B5/001 Primary

  Injecting additional fuel or reducing agents · CPC title

• C21B5/008 Primary

  Composition or distribution of the charge · CPC title

• C21B2300/02

  Particular sequence of the process steps · CPC title

• C21B5/003

  Injection of pulverulent coal · CPC title