Caracterización de la escoria negra producida en el horno ... | Renato Valencia Bedregal

Introduction to the Presentation

Overview of the Event

• The event is introduced as a platform for scientists to present their research, organized by the Latin American Network of Condensed Matter Physics.

• Participating institutions include universities from Peru, Brazil, Colombia, Mexico, Chile, Venezuela, Argentina, and Cambridge University.

Speaker Introduction

• Renato Valencia Bedregal from Universidad Nacional Mayor de San Marcos is welcomed as the speaker for this session.

• Renato completed his undergraduate studies in 2019 and is currently pursuing research on graphene simulations and iron insertion using DFT.

Project Overview

Thesis Background

• Renato's presentation focuses on his master's thesis related to a larger project named "Project Ademi," which deals with recovering materials from iron oxide waste.

• The project is funded by Fondid, CONITEC, and the World Bank.

Research Focus

• The main focus is on characterizing black slag produced in electric arc furnaces at Sider Perú before and after carbothermic reduction.

Steel Production Process

Stages of Steel Manufacturing

• Steel production involves three stages where waste materials are generated that are not needed for final steel products.

• The project aims to recycle these wastes to obtain pure iron necessary for producing new steel.

Global Steel Production Insights

• Asia leads global steel production with around 1000 million tons between 2013 and 2018; major producers include India, Japan, and China.

Methods of Iron Recovery

Reduction Techniques

• Various methods exist for reducing slag to obtain pure iron: hydrogen gas reduction and electroreduction in alkaline media are mentioned.

Carbothermic Reduction Method

• The primary method discussed in this work is carbothermic reduction involving adding carbon to reduce iron oxides into pure iron at high temperatures.

Case Study: Sider Perú

Sample Collection Details

• Samples were collected from Sider Perú's electric arc furnace on February 11th, 2020.

Electric Arc Furnace Operation

• In Sider Perú’s process, scrap steel is melted at approximately 1600ºC using an electric arc furnace.

Residual Waste Generation

Slag Types Produced

• During steel manufacturing at Sider Perú, various types of slag are produced including black slag during different stages of processing.

Quantitative Analysis

• For every 44 tons of scrap used in production, about 30 tons of steel are generated along with approximately 14 tons of slag.

Characterization Techniques Used

Analytical Methods Employed

• Various characterization techniques such as SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-ray Spectroscopy), X-ray fluorescence were utilized to analyze black slag samples.

Composition Findings

• Initial findings indicate that major components include calcium (47%), iron (32%), and silicon (11%).

X-ray Diffraction Results

Phase Identification

• X-ray diffraction revealed significant compounds like magnetite (Fe3O4), larnite (Ca2SiO4), indicating complex interactions within the sample material.

Implications for Reduction Processes

• Understanding these phases aids in determining effective strategies for reducing black slag into usable materials through carbothermic processes.

Magnetic Properties Analysis

Magnetometry Studies

• Magnetometry tests confirmed paramagnetic properties across samples despite containing ferromagnetic components like magnetite due to overall sample behavior.

Analysis of Black Slag Powder and Its Thermal Behavior

Overview of Black Slag Powder Production

• The black slag powder was produced by grinding for 60 seconds, resulting in a fine powder used for X-ray characterizations and other analyses.

• The powdered slag was stored in a ziplock bag for further testing, particularly to observe its behavior under elevated temperatures.

Thermal Gravimetric Analysis (TGA)

• A TGA test was conducted using the black slag powder mixed with graphite and carbon, heated from room temperature to 1300ºC in an inert atmosphere.

• The heating rate during the experiment was set at 10ºC per minute, revealing that reactions began around 960ºC when the slag started interacting with carbon.

Reaction Stages Observed

• Derivative analysis of the thermogravimetric curve indicated multiple mass loss events rather than a single reaction point.

• Two distinct reaction stages were identified: one between 960°C and approximately 1100°C, and another occurring above this range.

Endothermic Peaks Identification

• Differential scanning calorimetry (DSC) revealed two endothermic peaks at approximately 1058.3ºC and 1161.2ºC during the thermal analysis.

• These findings will inform future experiments using a tubular furnace with larger sample quantities to enhance reaction times.

Detailed Reaction Stages During Heating

Mass Loss Measurements

• In the first stage (960°C - 1140°C), there was a mass loss of about 27.20%, indicating significant chemical changes.

• A second stage (1140°C - 1185°C) showed an additional mass loss of approximately 5.51%.

Carbon Monoxide Generation

• The reactions resulted in carbon monoxide (CO) and carbon dioxide (CO2), contributing to observed mass losses as these gases escaped into the atmosphere.

Understanding Chemical Reactions

Possible Reactions Identified

• Literature suggests that iron oxides react with carbon at high temperatures, forming various compounds including CO2 which is released during reduction processes.

Simulation Studies

• Simulations have been performed alongside literature reviews to better understand these reactions' dynamics within specified temperature ranges.

Reduction Process Insights

Formation of Pure Iron

• In the second stage, iron oxide reacts further with carbon leading to pure iron production along with CO emissions as byproducts.

Importance of Temperature Control

• Maintaining precise temperature control is crucial for optimizing reduction efficiency and achieving desired product purity levels.

Tubular Furnace Experimentation

Sample Preparation

• For subsequent tests in a tubular furnace, a consistent ratio of black slag powder to carbon (5:1 ratio used previously in TGA tests).

Expected Outcomes

• Anticipated results include not only pure iron but also other elements due to impurities present in black slag powder after reduction processes.

Characterization Techniques Employed

X-Ray Diffraction Analysis

• X-ray diffraction confirmed presence of magnetite and wustite before reduction; post-reduction analysis aimed at identifying resultant phases such as alpha and gamma iron.

Mössbauer Spectroscopy Findings

• Mössbauer spectroscopy provided insights into different forms of iron present post-reduction, highlighting variations due to particle size distribution within samples.

Final Product Evaluation

Steel Composition Assessment

• Post-reduction steel composition analyzed through fluorescence techniques revealed residual calcium among other elements confirming impurity retention from original materials.

Publication Acknowledgment

• Results have been published detailing both black slag processing methods and outcomes related to recycling efforts within metallurgical contexts.

Discussion on Iron Production Methods

General Inquiry into Metallurgical Processes

• The speaker expresses interest in the extensive work done on iron production, questioning whether hydrometallurgical methods are used alongside traditional pyrometallurgical processes.

• Clarification is sought regarding the use of hydrogen and acid treatments for iron reduction, indicating a curiosity about alternative reduction methods.

Alternative Reduction Techniques

• Mention of using corn starch as a reducing agent for iron oxides highlights innovative chemical or biological approaches to metal reduction.

• The primary method discussed is carbothermic reduction, which involves high temperatures and carbon to reduce iron oxides effectively.

Recent Innovations in Iron Reduction

• Newer methods such as hydrogen gas reduction and electro-reduction in aqueous media are noted as recent advancements in the field.

• Current research focuses on scaling these innovative methods from laboratory settings to industrial applications while minimizing additional costs for steel companies.

Economic Considerations in Steel Production

Cost Implications of New Technologies

• Emphasis is placed on maintaining existing processes within steel companies to avoid increased operational costs associated with new machinery.

• The discussion reiterates that it’s crucial for steel manufacturers to continue utilizing established techniques unless more economical alternatives are discovered.

Efficiency and Yield Metrics

• A yield of approximately 60% reduced powder from the original sample is reported, with byproducts including carbon monoxide and carbon dioxide being released during the process.

Environmental Impact and Carbon Footprint

Addressing Carbon Emissions

• Concerns about carbon footprint lead to discussions about capturing CO2 emissions during production; simulations involving graphene were conducted to explore this possibility.

• Ongoing studies aim at developing effective methods for CO2 absorption using modified graphene materials.

Recovery of Valuable Elements

Potential for Additional Resource Extraction

• Discussion includes recovering valuable elements like zinc from red powders through thermal processes, showcasing potential recycling benefits beyond just steel production.

Applications Beyond Steel Manufacturing

• Black slag's versatility is highlighted, noting its use in road construction and concrete production, emphasizing recycling's broader implications across various industries.

Academic Engagement and Future Research Directions

Interaction Between Academia and Industry

• Recognition of efforts made by researchers like Renato to bridge gaps between basic science and industrial application is acknowledged by peers.

Suggestions for Further Investigation

• Encouragement from colleagues emphasizes the importance of continued research into improving industrial practices through scientific innovation.

Technical Discussions on X-ray Diffraction Analysis

Challenges Identifying Phases

• Issues arise regarding unidentified peaks in X-ray diffraction patterns; further analysis is needed to clarify these findings.

Spectral Adjustments

• Questions raised about adjusting spectral data suggest that multiple sextets may be present due to particle size variations affecting results.

Clarifications on Magnetic Properties

Misunderstandings About Magnetism

• A correction regarding magnetite's properties indicates it should be classified as ferrimagnetic rather than paramagnetic after reduction processes.

Exploring Broader Applications

Recycling Initiatives

• The conversation shifts towards exploring diverse applications for recycled materials beyond steel manufacturing, highlighting environmental sustainability efforts.