Direct reduced iron (DRI) heat treatment, products formed therefrom, and use thereof

Patent metadata

Field	Value
Publication number	US-11427877-B2
Application number	US-201816138022-A
Country	US
Kind code	B2
Filing date	Sep 21, 2018
Priority date	Sep 21, 2017
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

A DRI product and method of forming the DRI product. DRI is formed from a reducing process, and thereafter the DRI is subjected to another heat treatment that produces a DRI product. The DRI product formed has a metallic shell around at least a portion of a DRI core. The heat treatment may be delivered through the use of a plasma torch, a gas burner, an oven, or any other like heat source. The heat treatment may heat the DRI for a fraction of a second and quickly cool the DRI in order to melt the surface and form the metallic shell without vaporizing a significant portion of the DRI and without losing a significant amount of the latent energy in the DRI.

First claim

What is claimed is:

1. A method of forming a direct reduced iron (DRI) product, comprising:
providing a heat treatment to at least a portion of an outer surface of DRI at a temperature and for a time to melt at least the portion of the outer surface of the DRI, wherein the DRI was formed from direct reducing iron ore, and
wherein the heat treatment results in the DRI product having a DRI core with a plurality of voids and a metallic outer shell formed around at least the portion of the DRI core, wherein the metallic outer shell is non-porous and covers at least a portion of the plurality of voids of the DRI core.

2. The method of claim 1 , further comprising:
direct reducing the iron ore using a reducing gas or a carbon source to form the DRI.

3. The method of claim 1 , wherein the heat treatment comprises passing the DRI through a heat source, wherein the temperature of the heat treatment ranges between 440 degrees Fahrenheit to 20,000 degrees Fahrenheit.

4. The method of claim 3 , wherein passing the DRI through the heat source comprises dropping the DRI and using gravity or providing a motive force.

5. The method of claim 1 , wherein the metallic outer shell reduces an exposed surface area of the DRI core, and wherein breaking of the DRI product and rubbing of the DRI core with adjacent DRI products is reduced.

6. The method of claim 1 , wherein the heat treatment is performed by passing the DRI through a plasma torch, a gas burner, an oven, or any other conductive or radiant heat source.

7. The method of claim 1 , wherein the time exposed to the temperature ranges from 0.05 to 5 seconds.

8. The method of claim 1 , wherein the DRI is one or more DRI pellets.

9. The method of claim 1 , wherein the DRI product has a diameter ranging from 3 mm to 20 mm.

10. The method of claim 1 , further comprising:
pre-heating the DRI before performing the heat treatment at the temperature for the time to melt at least the portion of the outer surface of the DRI.

11. A direct reduced iron (DRI) product, comprising:
a DRI core with a plurality of voids; and
a metallic outer shell formed around at least a portion of the DRI core, wherein the metallic outer shell is non-porous and covers at least a portion of the plurality of voids of the DRI core;
wherein the metallic outer shell is formed around the DRI core by a heat treatment of at least a portion of an outer surface of DRI at a temperature and for a time to melt at least the portion of the outer surface of the DRI without melting the DRI core, and wherein the DRI was formed from direct reducing iron ore.

12. The DRI product of claim 11 , wherein the heat treatment comprises passing the DRI through a heat source, wherein the temperature of the heat treatment ranges between 440 degrees Fahrenheit to 50,000 degrees Fahrenheit.

13. The DRI product of claim 11 , wherein the DRI formed by the direct reducing of the iron ore comprises using a reducing gas or a carbon source to form the DRI.

14. The DRI product of claim 12 , wherein the temperature of the heat treatment ranges between 440 degrees Fahrenheit to 20,000 degrees Fahrenheit.

15. The DRI product of claim 12 , wherein the passing the DRI through the heat source comprises dropping the DRI and using gravity or by providing a motive force.

16. The DRI product of claim 11 , wherein the metallic outer shell reduces an exposed surface area of the DRI core, and wherein breaking of the DRI product and rubbing of the DRI core with adjacent DRI products is reduced.

17. The DRI product of claim 11 , wherein the heat treatment is performed by passing the DRI through a plasma torch, a gas burner, an oven, or any other conductive or radiant heat source.

18. The DRI product of claim 11 , wherein the time exposed to the temperature ranges from 0.05 to 5 seconds.

19. The DRI product of claim 11 , wherein the DRI is one or more DRI pellets.

20. The DRI product of claim 11 , wherein the DRI product has a diameter ranging from 3 mm to 20 mm.

Assignees

• Nucor Corp

Inventors

• True Bradford Granger
• Hendrickson David William

Classifications

• C21B13/0093

  Protecting against oxidation · CPC title

• C21B13/12

  in electric furnaces · CPC title

• C21B13/0086 Primary

  Conditioning, transformation of reduced iron ores · CPC title

• C21B13/143

  Injection of partially reduced ore into a molten bath · CPC title

• C21B13/0046 Primary

  making metallised agglomerates or iron oxide · CPC title