Utilization of Organic Mixed Biosludge from Pulp and Paper Industries and Green Waste as Carbon Sources in Blast Furnace Hot Metal Production

Tova Jarnerud,Pär G. Jönsson,Andrey V. Karasev,Chuan Wang,Frida Bäck

doi:10.3390/su13147706

Abstract

A six day industrial trial using hydrochar as part of the carbon source for hot metal production was performed in a production blast furnace (BF). The hydrochar came from two types of feedstocks, namely an organic mixed biosludge generated from pulp and paper production and an organic green waste residue. These sludges and residues were upgraded to hydrochar in the form of pellets by using a hydrothermal carbonization (HTC) technology. Then, the hydrochar pellets were pressed into briquettes together with commonly used briquetting material (in-plant fines such as fines from pellets and scraps, dust, etc. generated from the steel plant) and the briquettes were top charged into the blast furnace. In total, 418 tons of hydrochar briquettes were produced. The aim of the trials was to investigate the stability and productivity of the blast furnace during charging of these experimental briquettes. The results show that briquettes containing hydrochar from pulp and paper industries waste and green waste can partially be used for charging in blast furnaces together with conventional briquettes. Most of the technological parameters of the BF process, such as the production rate of hot metal (<1.5% difference between reference days and trial days), amount of dust, fuel rate and amount of injected coal, amount of slag, as well as contents of FeO in slag and %C, %S and %P in the hot metal in the experimental trials were very similar compared to those in the reference periods (two days before and two days after the trials) without using these experimental charge materials. Thus, it was proven that hydrochar derived from various types of organic residues could be used for metallurgical applications. While in this trial campaign only small amounts of hydrochar were used, nevertheless, these positive results support our efforts to perform more in-depth investigations in this direction in the future.

Highlights

Steel production is resource intensive and generates CO2 emissions
The main quality index in the iron and steel making industry is the cold strength of the briquette, the tumbler handling strength (TTH) [35]
These TTH values were considered to be too low, as they should be at least 75% for this specific blast furnace (BF)

Summary

Introduction

Steel production is resource intensive and generates CO2 emissions. In blast furnace (BF) operations, carbon is charged in the form of coke and pulverized coal to provide heat to melt the iron ore and to reduce the iron oxides to iron by a reduction of iron from oxides.The largest part of the CO2 emissions (85%) of the total emissions from the steel industry originates from the coal used to reduce iron ore [1]. Steel production is resource intensive and generates CO2 emissions. In blast furnace (BF) operations, carbon is charged in the form of coke and pulverized coal to provide heat to melt the iron ore and to reduce the iron oxides to iron by a reduction of iron from oxides. The largest part of the CO2 emissions (85%) of the total emissions from the steel industry originates from the coal used to reduce iron ore [1]. The use of renewable biomass resources is increasingly important to reduce greenhouse gas (GHG) emissions and to meet the increasing energy demand. Biomass is a biological or organic material, which can act as a source of renewable energy through thermal or biochemical transformation processes [3].

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Results

Conclusion