Minerals

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Research

19 pages, 23950 KiB

Open AccessArticle

Experiences of Bio-Coal Applications in the Blast Furnace Process—Opportunities and Limitations

by Lena Sundqvist Ökvist and Maria Lundgren

Minerals 2021, 11(8), 863; https://doi.org/10.3390/min11080863 - 10 Aug 2021

Cited by 14 | Viewed by 4177

Abstract

Metal production, and especially iron ore-based steel production, is characterized by high fossil CO₂ emissions due of the use of coal and coke in the blast furnace. Steel companies around the world are striving to reduce the CO₂ emissions in different ways, e.g., by use of hydrogen in the blast furnace or by production of iron via direct reduction. To partially replace fossil coal and coke with climate neutral bio-coal products that are adapted for use in the metal industry, e.g., at the blast furnace, is a real and important opportunity to significantly lower the climate impact in a short-term perspective. Top-charging of bio-coal directly to the blast furnace is difficult due to its low strength but can be facilitated if bio-coal is added as an ingredient in coke or to the mix when producing residue briquettes. Bio-coal can also be injected into the lower part of the blast furnace and thereby replace a substantial part of the injected pulverized coal. Based on research work within Swerim, where the authors have been involved, this paper will describe the opportunities and limitations of using bio-coal as a replacement for fossil coal as part of coke, as a constituent in residue briquettes, or as replacement of part of the injected pulverized coal. Results from several projects studying these opportunities via technical scale, as well as pilot and industrial scale experiments and modelling will be presented. Full article

(This article belongs to the Special Issue Bio-Coal for Metallurgical Processes)

► Show Figures

Figure 1

17 pages, 5050 KiB

Open AccessArticle

Effects of Briquetting and High Pyrolysis Temperature on Hydrolysis Lignin Char Properties and Reactivity in CO-CO₂-N₂ Conditions

by Aki Koskela, Anne Heikkilä, Davide Bergna, Justin Salminen and Timo Fabritius

Minerals 2021, 11(2), 187; https://doi.org/10.3390/min11020187 - 11 Feb 2021

Cited by 11 | Viewed by 2400

Abstract

Carbonaceous reductants for pyrometallurgical applications are usually obtained from fossil-based sources. The most important properties of the reductants greatly depend on the application and the feeding of the reductant into the process. However, the mechanical strength, calorific value, fixed carbon content, and reactivity of the reductant are the properties that usually define the applicability of the reductant for different processes. The reactivity of the biochars is usually high in comparison to metallurgical coke, which may restrict the applicability of the biochar in reduction processes. One cause of the higher reactivity is the higher surface area of the biochars, which can be suppressed with agglomeration treatment, e.g., briquetting. In this work, hydrolysis lignin was used for slow pyrolysis experiments to produce biochars. The biochars were pyrolyzed in briquetted form and in as-received form at various temperatures. The reactivity values of the biochars were tested in dynamic reactivity tests in a CO-CO₂-N₂ gas atmosphere at temperatures of up to 1350 °C. It was found that the yield of the hydrolysis lignin char only decreased by 3.36 wt% when the pyrolysis temperature was elevated from 600 to 1200 °C, while a decrease in yield of 4.88 wt% occurred when the pyrolysis temperature was elevated from 450 to 600 °C. The mass loss of hydrolysis lignin biochar in the reactivity experiment in CO-CO₂-N₂ atmosphere was significantly decreased from 79.41 wt% to 56.80 wt% when the hydrolysis lignin was briquetted before the slow pyrolysis process and the temperature of the pyrolysis process was elevated from 600 to 1200 °C. This means that the mass loss of the material was suppressed by 22.61 wt% due to the higher pyrolysis temperature and briquetting process. Full article

(This article belongs to the Special Issue Bio-Coal for Metallurgical Processes)

► Show Figures

Figure 1

14 pages, 1596 KiB

Open AccessArticle

Understanding of Blast Furnace Performance with Biomass Introduction

by Joel Orre, Lena Sundqvist Ökvist, Axel Bodén and Bo Björkman

Minerals 2021, 11(2), 157; https://doi.org/10.3390/min11020157 - 2 Feb 2021

Cited by 15 | Viewed by 4487

Abstract

The blast furnace still dominates the production and supply of metallic units for steelmaking. Coke and coal used in the blast furnace contribute substantially to CO₂ emissions from the steel sector. Therefore, blast furnace operators are making great efforts to lower the fossil CO₂ emissions and transition to fossil-free steelmaking. In previous studies the use of pre-treated biomass has been indicated to have great potential to significantly lower fossil CO₂ emissions. Even negative CO₂ emission can be achieved if biomass is used together with carbon capture and storage. Blast furnace conditions will change at substantial inputs of biomass but can be defined through model calculations when using a model calibrated with actual operational data to define the key blast furnace performance parameters. To understand the effect, the modelling results for different biomass cases are evaluated in detail and the overall performance is visualised in Rist- and carbon direct reduction rate (CDRR) diagrams. In this study injection of torrefied biomass or charcoal, top charging of charcoal as well as the use of a combination of both methods are evaluated in model calculations. It was found that significant impact on the blast furnace conditions by the injection of 142 kg/tHM of torrefied biomass could be counteracted by also top-charging 30 kg/tHM of charcoal. With combined use of the latter methods, CO₂-emissions can be potentially reduced by up to 34% with moderate change in blast furnace conditions and limited investments. Full article

(This article belongs to the Special Issue Bio-Coal for Metallurgical Processes)

► Show Figures

Journal Menu

Journal Browser

Bio-Coal for Metallurgical Processes

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Published Papers (3 papers)

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI