Sponge Iron Production via Layered Non-Oxidative Pyrolysis
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Solution Overview
Problem
Current methods for producing sponge iron face challenges in altering and reducing the high carbon content, which increases production costs due to the inherent carbon dissolution during the process, especially in coal and gas-based processes.
Innovation Solution
A process involving a sandwich of iron oxide and carbon sources, subjected to a non-oxidative heating process between 950° C to 1900° C, with optional organic materials or heat conductors to control carbon content and enhance iron extraction, allowing for flexible carbon adjustment and efficient removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional gas-based process is used to produce sponge iron, then iron oxide is reduced to metallic iron, but the sponge iron contains high carbon content of 4-6% which is difficult to alter
Solution Approach 1:
The iron oxide source is divided into multiple layers (first layer, second layer, third layer) with different carbon content characteristics. The first and third layers have lower carbon content while the second layer has higher carbon content, allowing selective reduction and carbon control in different zones of the sponge iron product.
Solution Approach 2:
Different layers of iron oxide source are assigned different carbon content properties. The first layer (carbon free or low carbon) and third layer (carbon free or low carbon) differ from the second layer (higher carbon content), creating local variations in carbon content that enable flexible overall carbon content adjustment in the final sponge iron product.
2Quantity of substance
If carbon content is reduced by controlled oxidation process, then carbon content decreases, but production cost increases
Solution Approach 1:
The carbon content is controlled during the initial reduction process by using iron oxide sources with predetermined carbon content characteristics. This preliminary control of carbon content during reduction eliminates or reduces the need for subsequent controlled oxidation processes, thereby reducing production costs while achieving desired carbon content levels.
3Quantity of substance
If oxygen partial pressure is increased to remove carbon, then carbon removal is attempted, but effective and efficient carbon removal breakthrough is not achieved
Solution Approach 1:
Instead of changing oxygen partial pressure to remove carbon, the invention changes the carbon content parameter of the iron oxide source itself. By selecting iron oxide sources with different inherent carbon content characteristics for different layers, carbon content is controlled at the source rather than attempting removal through parameter changes during processing, achieving efficient carbon control without compromising productivity.
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 process effectively reduces carbon content in sponge iron, optimizing production yield and cost by using stoichiometric amounts of carbon, achieving higher iron extraction rates and maintaining quality with reduced carbon levels.
Implementation Method 1
subjecting the sandwich of at least two layers to a heating process in a non-oxidative environment at a temperature between 950° C. to 1900° C.
Implementation Method 2
The at least one layer of organic material is burnt off at temperature range between 950° C. to 1900° C.
Data Source
AI summary
The process for producing the sponge iron includes the steps of preparing a sandwich of at least two layers wherein the at least two layers includes a first layer (10) of iron oxide source which content is carbon free or comprises of only self-contaminant carbon or carbonaceous and second layer (12) is a mixture of iron oxide source and carbon source and subjecting the sandwich of at least two layers to a pyrolysis process in a non-oxidative environment at temperature between 950° C. to 1900° C. for a period between 10 minutes to 36 hours. The carbon source in the second layer (12) is equal to or more than stoichiometric weight of carbon according to a predominant reaction. The non-oxidative pyrolysis occurs in a reactor. The sandwich of two layers is placed in a moving carrier (16) such as tray to accommodate the sandwich of two layers in the reactor.