Direct reduction method and rotary hearth furnace
AssigneeKabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.)
InventorsMakoto Nishimura, Hidetoshi Tanaka
Life of this patent
Estimating the term…
Abstract
Raw materials, including a metal oxide and a carbonaceous material, are supplied into a rotary hearth furnace. Then, the raw materials are heated and reduced by burners, which are arranged to cause a strong stirring action for an atmosphere around the raw materials, in an early reducing period that is defined as a period during which 70-80% of a total amount of a flammable gas generated from the raw materials is generated. In a latter period subsequent to the early reducing period, the raw materials are heated and reduced by burners arranged to cause a weak stirring action for an atmosphere around the raw materials, whereby a metal is manufactured. With the present invention, productivity can be improved and the fuel consumption per unit product can be reduced.
Claims13
A direct reduction method comprising the steps of:
- supplying raw materials, including a metal oxide and a carbonaceous material, into a rotary hearth furnace;
- defining, as an early reducing period, a period during which 70-80% of a total amount of a flammable gas generated from the raw materials is generated, and heating and reducing the raw materials in the early reducing period by first heating means arranged to cause a strong stirring action for an atmosphere around the raw materials;
- and
- heating and reducing the raw materials in a latter period subsequent to the early reducing period by second heating means arranged to cause a weak stirring action for an atmosphere around the raw materials.
A rotary hearth furnace for reducing raw materials, including a metal oxide and a carbonaceous material, to manufacture a metal, said rotary hearth furnace comprising:
- first heating means for creating a vortex to cause a strong stirring action for an atmosphere around the raw materials and arranged at a position inside said furnace corresponding to an early reducing period;
- and
- a second heating means for creating a vortex to cause a weak stirring action for an atmosphere around the raw materials and arranged at a position inside said furnace corresponding to a latter period subsequent to the early reducing period.
A rotary hearth furnace for reducing raw materials, including a metal oxide and a carbonaceous material, to manufacture a metal, said rotary hearth furnace comprising:
- a first heating device having a discharge element positioned in the vicinity of a ceiling of said furnace and adapted to cause a strong stirring action for an atmosphere around the raw materials, the first heating device being arranged at a position inside said furnace corresponding to an early reducing period;
- and
- a second heating device having a discharge element positioned to cause a weak stirring action for an atmosphere around the raw materials and arranged at a position inside said furnace corresponding to a latter period subsequent to the early reducing period.
A rotary hearth furnace for reducing raw materials, including a metal oxide and a carbonaceous material, to manufacture a metal, said rotary hearth furnace comprising:
- first heating means for generating flames in an obliquely downward direction, said first heating means being positioned in the vicinity of a ceiling of said furnace and at a position inside said furnace corresponding to an early reducing period;
- and
- second heating means positioned on a side wall of said furnace and at a position inside said furnace corresponding to a latter period subsequent to the early reducing period.
A method for reducing raw materials, including a metal oxide and a carbonaceous material, to manufacture a metal in a rotary hearth furnace, comprising the steps of:
- creating a vortex to cause a strong stirring action for an atmosphere around the raw materials at a position inside said furnace corresponding to an early reducing period;
- and
- creating a vortex to cause a weak stirring action for an atmosphere around the raw materials at a position inside said furnace corresponding to a latter period subsequent to the early reducing period.
Dependencies are inferred from the claim text.