Side Wall Nozzle Injection for Converter Dephosphorization
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Solution Overview
Problem
Current steelmaking processes using top blown or combined blown converters face inefficiencies in carbon and phosphorus removal from molten metal, particularly due to high lime powder losses and complex control mechanisms, with bulk lime dissolving poorly in foamy slags and resulting in limited dephosphorization.
Innovation Solution
The method involves a top blown converter with a movable upper nozzle and side wall nozzles mounted below the trunnion ring, injecting a mixture of an oxygen-free carrier gas and powdered dephosphorization agents, such as 2CaO.SiO2 powder, directly into the slag to enhance reactivity and reduce losses, allowing for efficient dephosphorization and carbon removal without complex control requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If powdered lime is blown onto the molten metal surface using side wall nozzles and water cooled lance, then dephosphorization efficiency is improved, but lime powder losses to gas cleaning systems increase
Solution Approach 1:
The patent introduces an oxygen-free carrier gas as an intermediary medium to transport the powdered lime from the side wall nozzles directly into the slag layer. This mediator enables the lime to reach the reaction zone without being lost to the gas cleaning system, while also preventing premature oxidation of the lime powder before it can react with phosphorus in the molten metal.
Solution Approach 2:
The patent extracts the oxygen component from the gas stream used to transport powdered lime, creating an oxygen-free carrier gas environment. This extraction prevents the lime powder from reacting with oxygen before reaching the slag, thereby reducing lime losses and improving dephosphorization efficiency by ensuring the lime reaches its intended reaction zone intact.
2Loss of substance
If bulk lime is used instead of powdered lime, then lime powder losses are reduced, but dissolution efficiency in foamy slag decreases
Solution Approach 1:
The patent changes the physical state parameter of the lime from bulk to powdered form, and simultaneously changes the chemical environment parameter by introducing oxygen-free carrier gas. This dual parameter change allows the powdered lime to be transported efficiently without oxidation losses while maintaining its high surface area for rapid dissolution in the foamy slag, thus improving both loss reduction and dissolution efficiency.
3Reliability
If complex control mechanisms are implemented for oxygen and powdered material injection, then refining process control is improved, but system complexity increases
Solution Approach 1:
The patent employs an oxygen-free carrier gas that naturally transports the powdered lime through the converter vessel without requiring active control mechanisms. The system self-regulates the injection process through the natural flow dynamics of the carrier gas, eliminating the need for complex control systems while maintaining reliable refining process control.
4Power
If powdered material is blown at the hot spot of the converter, then reaction intensity is improved, but powder losses to dedusting systems increase
Solution Approach 1:
The oxygen-free carrier gas serves as a protective intermediary that shields the powdered material from oxidation during transport to the hot spot zone. This mediator allows the powder to reach the high-temperature reaction zone with full reactivity potential while preventing losses to dedusting systems through the use of inert gas atmosphere throughout the injection pathway.
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 achieves high dephosphorization efficiency, reduces iron losses, and minimizes powdered material losses to gas cleaning systems, enabling the use of lower-priced raw materials and improving steel quality by reducing phosphorus content.
Implementation Method 1
The Oxygen ignites carbon dissolved in the molten metal to form carbon monoxide and carbon dioxide thus lowering carbon content of the molten metal
Implementation Method 2
The oxidized iron is then lost for the refining process which reduces a final steel yield
Implementation Method 3
Fluxes, in particular dephosphorization agents, such as e.g. burnt lime are fed into the vessel to form slag and to absorb impurities (including phosphor) during the steelmaking process
Data Source
Figure 1
AI summary
A method is provided for refining molten metal using a converter comprising at least one side wall nozzle mounted to a side wall of the converter. The method comprises the following steps: forming a bath of molten metal inside of the converter; blowing a mixture of an essentially Oxygen free carrier gas and powdered material onto and into a slag formed at least partially on the surface of the bath of molten metal using the at least one side wall nozzle.