Hot Briquetted Iron Powder Injection for Uniform Carbon Distribution

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Solution Overview

Problem

The production of steel using hydrogen direct reduction results in sponge iron that is difficult to melt due to the lack of cementite, leading to higher electricity requirements and electrode consumption in the EAF, and traditional briquetting methods result in inhomogeneous distribution of carbon or other powders with sponge iron pellets, causing unpredictable behavior in downstream processing.

Innovation Solution

A briquetting apparatus with a powder injection arrangement that injects carbon powder into a force-fed volume defined by the screw flighting and nip of the briquetting press, ensuring homogeneous mixing of carbon-free sponge iron pellets with carbon powder, reducing the risk of segregation and uneven distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional briquetting methods are used to mix carbon powder with sponge iron pellets, then the briquetting process can be performed, but the carbon distribution becomes inhomogeneous causing unpredictable behavior in downstream processing

Engineering Contradiction:
Improvecarbon distribution uniformityVSAvoiddownstream processing predictability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The invention introduces carbon powder into the material supply tank before the briquetting process begins, allowing the carbon to be distributed throughout the sponge iron pellets in advance. The powder injection arrangement delivers carbon powder to the material supply tank where it mixes with the sponge iron pellets before entering the briquetting press, ensuring homogeneous distribution from the outset rather than attempting to mix during briquetting.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The material supply tank acts as an intermediary zone where carbon powder and sponge iron pellets are introduced and allowed to mix before briquetting. This intermediate mixing zone enables the carbon particles to disperse uniformly throughout the pellet mass through the action of the screw feeder and material flow, achieving homogeneous distribution before the actual briquetting compression occurs.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If carbon-free sponge iron pellets are produced by hydrogen direct reduction, then CO2 emissions are reduced, but the sponge iron becomes difficult to melt due to lack of cementite

Engineering Contradiction:
ImproveCO2 emissionsVSAvoidmelting energy consumption
Core Design Contradiction:
Object-generated harmful factorsVSUse of energy by moving object

Solution Approach 1:

The invention changes the chemical composition parameter of the sponge iron by introducing carbon powder to compensate for the absence of cementite. By adjusting the carbon content through controlled powder injection, the melting characteristics of the hydrogen direct reduced iron are modified to match those of conventional carbon-containing sponge iron, thereby maintaining energy efficiency in the melting process.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite material system by combining carbon-free sponge iron pellets with added carbon powder. This composite approach allows the benefits of hydrogen direct reduction (low CO2 emissions) to be retained while compensating for the lack of cementite through external carbon addition, achieving both environmental and metallurgical objectives.

Inventive Principle:
Principle #40Composite materials

3Use of energy by moving object

If carbon powder is added to sponge iron pellets, then meltability is improved, but the risk of segregation and uneven distribution increases

Engineering Contradiction:
Improvemelting energy consumptionVSAvoidcarbon distribution uniformity
Core Design Contradiction:
Use of energy by moving objectVSStability of the object's composition

Solution Approach 1:

The invention performs the carbon distribution action in advance by introducing the powder into the material supply tank before briquetting. This preliminary introduction allows the carbon particles to become uniformly distributed throughout the sponge iron pellets through the natural mixing action of the material flow and screw feeder, preventing segregation that would occur if carbon were added later or during the briquetting process itself.

Inventive Principle:
Principle #10Preliminary action

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 apparatus achieves well-distributed carbon in the briquettes, improving meltability and reducing energy consumption in the EAF, while maintaining consistent composition and behavior in downstream processing.

Implementation Method 1

a source of pressurized carrier gas (79) connected to said line inlet (75) and arranged to provide a predetermined gas flow through said injection line (73) when in operation

Methodology Applied
Scientific EffectGas flow injection: Jet

Implementation Method 2

a screw feeder (41) comprising a screw (43) arranged within said material supply tank (31) and arranged to convey the hot sponge iron pellet feed towards the nip (29) of the briquetting press

Methodology Applied
Scientific EffectScrew conveyance: Screw

Implementation Method 3

the rollers (21, 21') arranged to be synchronously counter-rotatable... the rollers (21, 21') arranged to briquette a feed of the hot sponge iron pellet feed

Methodology Applied
Scientific EffectMechanical compression: Compression

Implementation Method 4

a briquette cooler apparatus arranged to cool the string of briquettes

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4430216B1An apparatus for producing hot briquetted iron
Publication Date: 2025.10.15 HYBRIT DEV AB
  • EP4430216B1 patent drawingFigure 1
  • EP4430216B1 patent drawingFigure 2a~2c
  • EP4430216B1 patent drawingFigure 3

AI summary

The present disclosure relates to an apparatus for producing hot briquetted iron. The apparatus (1) comprises: a briquetting press (10) and a force feeder arrangement (30). The apparatus further comprises: a powder injection arrangement (70), the powder injection arrangement comprising a powder dosing unit (71) and at least one injection line (73). The powder dosing unit is arranged to be able to dose powder at a predetermined rate to the at least one injection line. Each injection line extends from a line inlet (75) to a line outlet (77). Each line inlet is arranged to be connectible to a source of pressurized carrier gas (79) and each line outlet is arranged to be able to inject powder into a material supply tank of the force feeder arrangement. The disclosure further relates to a method for producing hot briquetted iron using such an apparatus.