Top-Blowing Lance Flame Heating for Hot Metal Refining
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Solution Overview
Problem
Existing methods for refining hot metal in converters face challenges such as contamination, extended refining time, increased CO2 emissions, and equipment safety issues when using carbon sources or controlling secondary combustion rates, which hinder the efficient use of cold iron sources like iron and steel scrap.
Innovation Solution
A method involving a top-blowing lance that supplies a mixture of a lime-based flux, iron oxide, and a combustible material with a fuel gas and inert gas as a carrier, forming a flame to efficiently transfer heat to the hot metal without risking combustion or heat-up in the lance channels, thereby increasing the thermal margin and cold iron source content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a carbon source is added to the slag to combust and transfer heat to hot metal, then the temperature of hot metal is increased, but the hot metal is contaminated with sulfur from the carbon source and CO2 emissions increase
Solution Approach 1:
The invention changes the chemical composition parameters of the refining powder from carbon-based to metal-based (Fe, Al, Si, Mn, Mg), fundamentally altering the heating mechanism from carbon combustion to metal oxidation. This parameter change eliminates sulfur contamination while maintaining heat transfer effectiveness through controlled oxidation reactions of metal powders.
Solution Approach 2:
The invention uses inexpensive metal powders (Fe, Al, Si, Mn, Mg) as disposable refining agents that are consumed during the oxidation process. These metal powders serve as both the heat source and the refining agent, eliminating the need for separate carbon sources and reducing CO2 emissions while providing effective sulfur-free heating.
2Temperature
If the secondary combustion rate is increased to heat hot metal, then the temperature of hot metal is increased, but the decarburization rate decreases and refining time is extended
Solution Approach 1:
The invention introduces metal powders as intermediary substances that facilitate heat transfer from the oxidation zone to the hot metal. These metal powders act as a thermal mediator, absorbing heat during their oxidation and directly transferring it to the hot metal, thereby improving heating efficiency without interfering with the decarburization reaction kinetics.
Solution Approach 2:
The invention performs preliminary heating of the hot metal through metal powder oxidation before the main decarburization process. By pre-heating the hot metal to the required temperature, the subsequent decarburization reaction can proceed more rapidly and efficiently, improving overall refining productivity without extending the total refining time.
3Quantity of substance
If dephosphorization is performed as a pretreatment to remove phosphorus from hot metal, then the phosphorus content is reduced, but the temperature of hot metal decreases and the contents of carbon and silicon are reduced
Solution Approach 1:
The invention merges the dephosphorization function with the heating function by using metal powders that serve dual purposes: removing phosphorus through oxidation and generating heat through their own oxidation reactions. This combination allows simultaneous dephosphorization and temperature maintenance, eliminating the need for separate heating steps after dephosphorization.
Solution Approach 2:
The metal powders used for dephosphorization serve themselves by generating the heat required for the process through their own oxidation reactions. The oxidation of metal powders (Fe, Al, Si, Mn, Mg) releases substantial heat that directly compensates for the temperature drop during dephosphorization, making the process self-sufficient in terms of thermal energy.
4Manufacturing precision
If refining powder containing metal or carbon is supplied through the lance, then the refining function is improved, but the refining powder may heat up or combust in the lance channels causing safety issues
Solution Approach 1:
The invention creates an inert or low-oxygen atmosphere within the lance channels by controlling the gas composition (using N2 or CO as carrier gases) and timing the oxidation reaction to occur primarily after the powder exits the lance. This prevents premature combustion of the metal or carbon powders in the lance channels, ensuring equipment safety while maintaining refining efficiency.
Solution Approach 2:
The invention performs preliminary protection of the refining powder during transport through the lance by maintaining a controlled atmosphere that prevents oxidation. The actual oxidation and heat-generating reaction is timed to occur after the powder reaches the hot metal, ensuring safe transport while achieving the desired refining effect.
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 enhances heat transfer efficiency and productivity, allowing for a higher content of cold iron sources in hot metal dephosphorization or decarburization processes while ensuring equipment safety and reducing CO2 emissions.
Implementation Method 1
forming a flame at the leading end of a top-blowing lance to increase the temperature of the hot metal with the sensible heat of a powder heated by the flame or with the heat of combustion of a combustible material combusted by the flame
Implementation Method 2
heat transfer efficiency... allowing for a higher content of cold iron sources
Implementation Method 3
increase the temperature of the hot metal with the sensible heat of a powder heated by the flame
Implementation Method 4
heat of combustion of a combustible material combusted by the flame... heat transfer efficiency
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is a method for refining hot metal in a converter by dephosphorizing or decarburizing the hot metal while forming a burner flame at the leading end of a top-blowing lance to transfer the heat of the flame to the hot metal, thereby providing high heat transfer efficiency and productivity without the risk of heat-up or combustion in a channel in the top-blowing lance so that the content of a cold iron source such as iron and steel scrap can be increased. A method for refining hot metal in a converter using a top-blowing lance 3 having a refining powder supply channel, a combustion oxidizing gas supply channel, and a refining oxidizing gas supply channel that are separate from each other includes supplying at least one of a lime-based flux, iron oxide, and a combustible material as a refining powder 29 from the refining powder supply channel to a surface of the hot metal using a fuel gas or a mixture of the fuel gas and an inert gas as a carrier gas while supplying a combustion oxidizing gas from the combustion oxidizing gas supply channel to form a flame below a leading end of the top-blowing lance, and supplying a refining oxidizing gas from the refining oxidizing gas supply channel to the surface of the hot metal.