Granulated Metalliferous Feed for Pneumatic Sludge Injection
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Solution Overview
Problem
The challenge is to recycle iron-containing sludge from steelmaking processes, such as Basic Oxygen Steelmaking sludge, which cannot be recycled via a sinter plant in alternative ironmaking processes like the HIsarna process, leading to waste storage and environmental dust issues, while maintaining the material's transportability and usability in a metallurgical vessel.
Innovation Solution
A method involving pre-drying iron-containing sludge to 15-30% moisture, mixing with a binder to form granulates of less than 4 mm size, and further drying to 3% moisture, creating a metalliferous feed suitable for pneumatic transport and injection into a metallurgical vessel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If iron-containing sludge is dried to low moisture content, then dust emissions are reduced and material can be stored, but the sludge re-oxidizes and loses its reduced form properties
Solution Approach 1:
The sludge is pre-dried to a controlled moisture content of 15-30% before granulation, which prepares the material for subsequent low-moisture storage without allowing re-oxidation. This preliminary drying action establishes the right conditions for the next steps while preserving the reduced iron properties.
Solution Approach 2:
The invention controls moisture content as a critical parameter through staged drying: first to 15-30% during pre-drying, then to maximum 3% during final drying. This parameter control allows the material to be stored in low-moisture conditions without re-oxidizing, as the reduced form is protected within the granulated structure.
2Productivity
If sludge is recycled via sinter plant, then iron-containing sludge can be reused, but pneumatic transport cannot be used due to particle size and moisture issues
Solution Approach 1:
The sludge is transformed from a continuous moist material into discrete granulates with controlled particle size (less than 4mm). This segmentation into uniform particles enables pneumatic transport while maintaining recyclability, bridging the gap between sinter plant recycling and modern transport requirements.
Solution Approach 2:
The invention replaces traditional mechanical handling systems with pneumatic transport capability. By controlling particle size and moisture content, the granulated sludge can be conveyed through pneumatic systems, offering a more efficient and cleaner alternative to mechanical conveyance methods.
3Object-generated harmful factors
If sludge moisture content is too low, then dust emissions are reduced, but the sludge re-oxidizes and cannot be used in ironmaking process
Solution Approach 1:
The invention establishes specific moisture content ranges (15-30% during pre-drying, maximum 3% after final drying) that balance dust emission reduction with prevention of re-oxidation. These parameter specifications ensure the material remains suitable for ironmaking while minimizing harmful dust emissions.
Solution Approach 2:
The granulated sludge forms a composite structure where the binder material and granulate matrix protect the reduced iron from re-oxidation while allowing moisture control. This composite structure enables the material to withstand low-moisture storage and transport conditions without compromising its ironmaking suitability.
4Speed
If granulate particle size is reduced for pneumatic transport, then transport efficiency improves, but handling and injection requirements become more stringent
Solution Approach 1:
The invention specifies a particle size threshold (less than 4mm) that optimizes pneumatic transport performance while remaining practical for handling and injection. This parameter balance ensures efficient transport without requiring excessively tight size control that would complicate the manufacturing process.
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 method enables the formation of granulates that are transportable, reduce dust emissions, maintain caloric value, and optimize melting properties, allowing for efficient use in ironmaking processes without additional equipment adjustments.
Implementation Method 1
pre-drying an iron containing sludge by drying means, preferably a filter press, to an amount of 15 to 30% (w/w) moisture
Implementation Method 2
the metalliferous feed is subsequently injected into a cyclone part of a metallurgical vessel
Data Source
AI summary
A method of introducing a metalliferous feed in an ironmaking process, the method including the steps of, pre-drying an iron containing sludge by drying means to an amount of 15 to 30% (w/w) moisture, mixing the pre-dried iron containing sludge with a binder material to obtain a granulate, having a particle size of less than 4 millimeter and drying the granulate to a maximum of 3% (w/w) moisture, thereby forming the metalliferous feed, wherein the metalliferous feed is subsequently injected into a cyclone part of a metallurgical vessel.