Direct Smelting Vessel Slag Viscosity Control
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Solution Overview
Problem
The HIsmelt process is not suitable for smelting metalliferous feed materials containing iron oxides and titanium oxides, such as titanomagnetite and ilmenite, and optionally vanadium oxides, due to limitations in controlling process conditions to achieve effective smelting and product quality.
Innovation Solution
Control the process conditions in a direct smelting vessel to maintain a molten slag with viscosity between 0.5-5 poise at 1400-1550°C, adjusting temperature, pressure, and composition to produce molten iron and high-titanium oxide slag, with specific control of FeO and CaO content to manage oxygen potential and viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the HIsmelt process is used for smelting metalliferous feed materials containing iron oxides and titanium oxides, then the process can handle these materials, but the process conditions cannot be effectively controlled to achieve desired smelting results and product quality
Solution Approach 1:
The patent applies parameter changes by precisely controlling slag viscosity within 0.5-5 poise and temperature within 1400-1550°C range. This involves adjusting chemical composition parameters (FeO content at 3-10 wt%, CaO content at 10-30 wt%) to achieve the desired viscosity window, which resolves the process control effectiveness issue when handling titaniferous materials
Solution Approach 2:
The patent implements dynamics by maintaining the slag in a molten state with controlled viscosity that allows for optimal mass transfer and heat transfer. The dynamic control of viscosity through composition adjustment enables the system to adapt to different feed materials while maintaining reliable process control
2Productivity
If traditional blast furnaces are used for smelting titaniferous materials, then the process is simple and robust, but the efficiency and product quality are inferior
Solution Approach 1:
The patent achieves superior smelting efficiency by operating at elevated temperatures (1400-1550°C) and controlling slag viscosity (0.5-5 poise), which enhances reaction kinetics and mass transfer rates compared to traditional blast furnaces. The direct injection of oxygen and feed materials creates intense mixing and heat transfer, dramatically improving productivity
Solution Approach 2:
The patent applies preliminary action by pre-heating the injected oxygen to high temperatures before injection, and by pre-forming the molten bath with appropriate composition before feed material injection. This preliminary preparation ensures immediate and efficient reactions upon contact, enhancing overall smelting efficiency without proportionally increasing complexity
3Manufacturing precision
If slag viscosity is not controlled within 0.5-5 poise, then the process is simpler to operate, but the smelting effectiveness and product quality deteriorate
Solution Approach 1:
The patent establishes clear parameter ranges (viscosity: 0.5-5 poise, temperature: 1400-1550°C, FeO: 3-10 wt%, CaO: 10-30 wt%) that define the optimal operating window. By controlling composition within these ranges, the system achieves both high product quality and manageable operational complexity, as the parameters guide operator decisions
Solution Approach 2:
The patent implements feedback control by monitoring slag composition and viscosity, and adjusting feed material ratios and oxygen injection rates accordingly. This closed-loop control ensures the slag maintains optimal viscosity for effective smelting while providing operators with clear guidance, balancing precision with ease of operation
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
This approach enables effective smelting of titaniferous materials, producing molten iron with vanadium and high-titanium oxide slag suitable for pigment-grade titania production, outperforming traditional blast furnaces in efficiency and product quality.
Implementation Method 1
a solid carbonaceous material, typically coal, which acts as a reductant of the iron ore feed material
Implementation Method 2
A blast of oxygen-containing gas, typically oxygen-enriched air or pure oxygen, is injected into an upper region of the vessel through a downwardly extending lance to cause post-combustion of reaction gases released from the molten bath
Implementation Method 3
which provide an effective medium to transfer to the bath the thermal energy generated by post-combusting reaction gases above the bath
Data Source
Figure 1
Figure 2~3
AI summary
A molten bath-based direct smelting process comprises controlling the process conditions in a direct smelting vessel so that molten slag in a molten bath of metal and slag in the vessel has a viscosity in a range of 0.5-5 poise when the slag temperature is in a range of 1400-1550°C in the molten bath in the vessel.