Refractory-Lined Lance for Steelmaking Slag Modification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for modifying steelmaking slag to reduce expansion caused by free CaO, such as aging and modification processes, face challenges like long processing times, high costs, and lance wear due to high temperatures, which affect the stability and economic viability of the process.
Innovation Solution
A method involving blowing an oxygen-containing gas with a concentration of 20 volume% or more into molten steelmaking slag at temperatures above 1,450°C using a lance with a refractory thickness of 5 mm or more, and a linear velocity of 30 m/sec or more to convert free CaO into a stable mineral phase, reducing lance wear and maintaining expansion stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a metal lance is used to blow oxygen-containing gas into molten slag at 1,450°C or more, then the modification process can be performed effectively, but the lance quickly burns out due to high temperature
Solution Approach 1:
The lance is constructed as a composite structure with a metal pipe core providing mechanical strength and a refractory material coating (5mm or more thickness) providing thermal protection. This composite design allows the lance to withstand the high temperatures of molten slag (1,450°C or more) while maintaining structural integrity and reducing burnout.
Solution Approach 2:
The refractory material serves as an intermediary layer between the metal pipe and the molten slag, protecting the metal from direct thermal exposure. This intermediary coating enables the metal lance to function effectively in high-temperature environments without quick burnout.
2Ease of manufacture
If atmospheric aging is used to stabilize f-CaO in slag, then the process is simple, but it takes several months for f-CaO to stabilize
Solution Approach 1:
The invention changes the temperature parameter by maintaining slag at high temperature (1,450°C or more) during modification, which dramatically accelerates the stabilization of f-CaO compared to atmospheric aging at ambient temperature. This parameter change reduces the aging time from several months to a much shorter period while maintaining process simplicity through direct oxygen injection.
3Loss of time
If vapor aging is used to accelerate hydration reaction, then processing time is shorter than atmospheric aging, but a large quantity of water vapor is required increasing processing costs
Solution Approach 1:
Instead of using vapor aging that requires large quantities of water vapor, the invention changes the approach by maintaining high temperature (1,450°C or more) and introducing oxygen-containing gas to promote oxidation and stabilization of f-CaO. This alternative parameter change achieves rapid stabilization without the high energy consumption and cost associated with generating and supplying large amounts of water vapor.
4Reliability
If the thickness of refractory coating on the lance is increased to reduce wear, then lance durability improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The invention optimizes the refractory coating thickness to 5mm or more, which provides sufficient thermal protection and wear resistance without excessive complexity. This parameter optimization balances durability improvement with manageable device complexity and manufacturing cost, avoiding the need for overly complex multi-layer or reinforced structures.
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 effectively reduces lance wear, lowers processing costs, and ensures the stability of steelmaking slag, making it suitable for use as roadbed material by converting free CaO into a stable compound without significant temperature drops or increased costs.
Implementation Method 1
blowing oxygen-containing gas into a steelmaking slag to be modified having an internal temperature of 1,450°C or more
Implementation Method 2
a refractory having a thickness of 5 mm or more and blowing the oxygen-containing gas into a steelmaking slag
Data Source
Figure 1~2
Figure 3
AI summary
A method of modification of steelmaking slag is provided whereby wearing of a lance during modification can be reduced while ensuring expansion stability for the steelmaking slag having undergone a modification process. A method is provided that modifies steelmaking slag by blowing oxygen-containing gas into a molten steelmaking slag. The method includes dipping a lance made of a metal pipe around which is installed a refractory having a thickness of 5 mm or more and blowing oxygen-containing gas into a steelmaking slag to be modified having an internal temperature of 1,450°C or more.