Direct Reduced Iron Metallic Shell Formation

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Solution Overview

Problem

Direct reduced iron (DRI) is susceptible to oxidation, rusting, and ignition during storage and transportation, leading to increased risk of melting and the production of fines and dust, which pose environmental and handling challenges.

Innovation Solution

A heat treatment process that forms a metallic shell around a DRI core using a plasma torch or other heat sources, reducing the exposed surface area and minimizing the loss of metallic iron and carbon content, thereby enhancing the product's strength and reducing the likelihood of fracturing and oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If DRI is stored and transported in traditional forms, then handling and storage are straightforward, but the DRI is susceptible to oxidation, rusting, and ignition, leading to production of fines and dust

Engineering Contradiction:

Improvestability during storage and transportVSAvoidfines and dust production

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

A metallic shell is formed around the DRI core through controlled melting and solidification, creating a protective coating that acts as a barrier against oxidation and mechanical degradation, thereby reducing fines and dust production during handling and storage

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The DRI product becomes a composite structure with a DRI core and a metallic shell layer, combining the high iron content benefits of DRI with the protective properties of the metallized surface to prevent oxidation and reduce fragmentation

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If the exposed surface area of DRI is reduced, then oxidation and ignition risk are minimized, but the DRI strength and handling properties deteriorate

Engineering Contradiction:

Improveoxidation and ignition riskVSAvoidDRI structural strength

Core Design Contradiction:

Object-affected harmful factorsVSStrength

Solution Approach 1:

The metallic shell provides both protection against oxidation and ignition by limiting exposed surface area, and simultaneously enhances structural strength by acting as a reinforcing coating that prevents fragmentation during handling

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The composite structure of DRI core with metallic shell combines the chemical reactivity benefits of exposed DRI surface with the mechanical protection and oxidation resistance of the metallized coating, achieving both reduced oxidation risk and improved strength

Inventive Principle:

Principle #40Composite materials

3Reliability

If heat treatment is applied to form a metallic shell, then oxidation resistance and strength are improved, but energy consumption and process complexity increase

Engineering Contradiction:

Improveoxidation resistanceVSAvoidheat treatment energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The heat treatment process utilizes phase transition of the DRI surface material from solid to liquid and back to solid, forming a metallic shell through controlled melting and solidification that provides oxidation resistance with relatively efficient energy use

Inventive Principle:

Principle #36Phase transitions

Solution Approach 2:

By controlling heat treatment parameters such as temperature, exposure time, and cooling rate, the process forms a protective metallic shell while minimizing energy consumption and avoiding excessive melting that would waste material and energy

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The process results in a DRI product with a reduced surface area, minimizing the formation of fines and dust, reducing the risk of ignition and oxidation, and improving handling and storage efficiency while maintaining the latent heat energy for efficient steelmaking.

Implementation Method 1

heating DRI at a temperature for a time to melt at least a portion of the outer surface of the DRI

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

The heat treatment may be delivered through the use of a plasma torch

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 3

The heat treatment may heat the DRI for a fraction of a second and quickly cool the DRI

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 4

The heat treatment may heat the DRI for a fraction of a second and quickly cool the DRI

Methodology Applied

Scientific EffectCooling: Cooling

Data Source

PatentUS11427877B2Direct reduced iron (DRI) heat treatment, products formed therefrom, and use thereof

Publication Date: 2022.08.30 NUCOR CORP

AI summary

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.