Ferroalloy Refining via Supersonic Particulate Injection
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Solution Overview
Problem
Existing methods for refining ferroalloys, such as ferrochrome and stainless steel, face challenges in controlling temperature rises during the decarburization process, leading to excessive wear on refractory linings and frequent converter relining, as well as reduced productivity due to exothermic reactions and chromium oxidation.
Innovation Solution
Introducing metallurgically acceptable particulate materials, like chromium or manganese oxides, into the melt via a supersonic gas jet shrouded by another supersonic gas jet, which acts as a coolant and oxidizing agent, reducing the need for oxygen from below and minimizing refractory damage by controlling temperature rises and optimizing reaction rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If oxygen is blown into the melt to decarburize the ferroalloy, then the carbon content is reduced, but the temperature increases excessively due to exothermic reactions
Solution Approach 1:
A particulate material is introduced as an intermediary substance that absorbs the exothermic heat of oxidation reactions. The particles circulate in the melt, absorbing thermal energy when oxidizing and releasing it gradually, thereby acting as a heat buffer that prevents excessive temperature rise during decarburization
Solution Approach 2:
The invention changes the thermal parameters of the system by introducing particulate material that modifies the heat capacity and thermal conductivity of the melt. The particles alter the thermal behavior through their specific heat capacity and gradual oxidation process, transforming the thermal profile of the decarburization reaction
2Quantity of substance
If oxygen is blown into the melt to decarburize, then carbon is removed, but chromium oxide is formed and chromium is lost
Solution Approach 1:
The particulate material serves as an intermediary oxidizing agent that preferentially reacts with carbon instead of chromium. By controlling the oxidation to occur primarily with the introduced particles rather than with chromium in the alloy, chromium loss is minimized while decarburization proceeds effectively
Solution Approach 2:
The introduced particulate material provides additional oxidizing capacity that accelerates carbon oxidation. The particles act as a controlled oxidizing medium that directs the oxidation reaction toward carbon removal while suppressing unwanted chromium oxidation through selective reactivity
3Productivity
If oxygen is blown through submerged tuyeres, then decarburization occurs, but the refractory lining is damaged and relining is required frequently
Solution Approach 1:
The invention extracts the oxidation reaction from the refractory-lined converter environment by introducing particulate material that oxidizes carbon in the bulk melt. This removes the harmful localized oxidation at the tuyere-refractory interface, eliminating the primary cause of refractory damage while maintaining decarburization productivity
Solution Approach 2:
The invention converts the harmful exothermic oxidation reaction into a beneficial process by directing it to occur with introduced particulate material rather than with the refractory lining. The oxidation energy is harnessed to drive decarburization while the particulate material protects the refractory from thermal and chemical damage
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 method effectively limits temperature increases, reduces converter wear, increases productivity, and allows for less frequent relining by using the particulate materials' cooling and oxidizing effects, while maintaining efficient decarburization and chromium retention.
Implementation Method 1
a first supersonic gas jet which travels to the melt
Implementation Method 2
the particulate material being carried into the melt in a first supersonic gas jet
Implementation Method 3
there is an associated tendency for an excessive temperature to be created in the converter because of the exothermic nature of the oxidation reactions
Implementation Method 4
the particulate material being carried into the melt in a first supersonic gas jet... acts as a coolant and oxidizing agent, reducing the need for oxygen from below and minimizing refractory damage by controlling temperature rises
Implementation Method 5
the molten alloy is blown from beneath the surface with oxygen so as to oxidise the carbon to carbon monoxide
Data Source
AI summary
A method of refining a ferroalloy includes the step of blowing molecular oxygen or a gas mixture including molecular oxygen into a melt of the ferroalloy. A metallurgically acceptable particulate material is introduced from above into the melt. The particulate material is carried into the melt in a first supersonic gas jet which travels to the melt shrouded by a second gas jet.