Samane Maroufi

Carbothermal reduction of iron and silicon oxides in ironstone ore

The paper examines carbothermal reduction of iron and silicon oxides in ironstone ore which can be a valuable source of iron and silicon in production of ferrosilicon and silicomanganese. The original ore was provided as a crushed ore and a lumpy ore. Crushed ironstone ore contained higher Fe2O3 concentration (40.6 wt-%) and lower SiO2 content (44.3 wt-%) compared to the lumpy one (21.2 wt-% Fe2O3, 68.9 wt-% SiO2); phases detected by XRD and SEM/EDS analyses included haematite and quartz. Reduction of ironstone ores by graphite was examined at the temperature range 1400–1600°C in CO atmosphere. XRD analysis of both ironstone ores reduced at 1400°C identified the presence of quartz, cristobalite and metallic iron. Reduction of iron oxides was close to completion at 1400°C; with increasing temperature to 1500°C, Fe3Si was formed. Quartz and cristobalite were also present in the reduced sample, while no Fe was detected by both XRD and SEM/EDS analyses of samples reduced at 1500°C. The crushed ore reduced at 1600°C, contained Fe5Si3, Fe3Si, Fe2Si, SiC and cristobalite; the same phases except Fe5Si3 were also identified in the lumpy ore reduced at this temperature. Extent of silica reduction increased with increasing temperature. Equilibrium phases in carbothermal reduction of ironstone ores were analysed using CSIROs Multiphase Equilibrium model. In general, calculated results were consistent with experimental data, although equilibrium was not fully reached under experimental conditions of this study.

Nano-carbons from waste tyre rubber: An insight into structure and morphology

This study reports on the novel and sustainable synthesis of high value carbon nanoparticles (CNPs) from waste tyre rubber (WTR), using an innovative high temperature approach. As waste tyres are composed, primarily, of carbon - accounting for some 81.2wt% - they represent a promising source of carbon for many potential applications. However, cost-effective options for their processing are limited and, consequently, billions of waste tyres have accumulated in landfills and stockpiles, posing a serious global environmental threat. The rapid, high temperature transformation of low value WTR to produce valuable CNPs, reported here, addresses this challenge. In this study, the transformation of WTRs was carried out at 1550°C over different reaction times (5s to 20min). The structure and morphology of the resulting CNPs were investigated using X-ray diffraction (XRD), Raman spectroscopy, X-ray photon spectroscopy (XPS), N2 isothermal adsorption method and scanning electron microscopy (SEM). The formation of CNPs with diameters of 30 and 40nm was confirmed by Field Emission Electron Microscopy (FE-SEM). Longer heating times also resulted in CNPs with regular and uniform spherical shapes and a specific surface area of up to 117.7m2/g, after 20min. A mechanism that describes the formation of CNPs through mesophase nuclei intermediate is suggested.

Characterisation and reduction of ironstone ore by CO gas

Ironstone ore can be a valuable source of iron and silicon for the production of silicomanganese and other alloys. This paper provides analyses of the chemical and phase composition of ironstone and information on the reduction of ironstone by carbon monoxide at temperatures in the range 800–1150°C. Ironstone was provided as crushed and a lumpy ore. Crushed ironstone ore contained higher Fe2O3 concentration (40.6 wt-%) and lower SiO2 content (44.3 wt-%) compared to the lumpy one (21.2 wt-% Fe2O3, 68.9 wt-% SiO2). The main phases in the ore detected by XRD and SEM/EDS analyses were haematite and quartz. Two major reactions were observed upon heating ironstone in CO atmosphere, namely; partial reduction of iron oxides and formation of fayalite. The rate of fayalite formation increased with increasing temperature. Ore porosity significantly decreased upon heating. Ore softening and partial melting started at 1100–1150°C with a significant negative effect on iron oxide reduction. The weight loss of the crushed ore increased with increasing temperature to 1000°C and decreased when the temperature increased further to 1150°C. The weight loss of lumpy ore decreased with increasing temperature from 1100 to 1150°C. Based on the analysis using LECO oxygen analyser, the degree of iron oxide reduction in the crushed ore was estimated to be 82.4% at 1000°C, 68.8% at 1100°C and 33.1% at 1150°C. The degree of iron oxide reduction in the lumpy ore was 79.5% at 1000°C, 82.7% at 1100°C and 47.2% at 1150°C. No metallic iron was detected by XRD in samples heated in CO atmosphere at 1150°C, although a small amount of metallic iron was observed in SEM/EDS analysis. Equilibrium phases in the reduction of ironstone ores by CO were calculated using MPE model and compared with experimental data, these calculations also provided useful data on behaviour of ironstone during reduction at different temperatures.

Green Manufacturing: A Key to Innovation Economy

This thematic section focuses on different aspects of transformations of ‘e-waste’ into value-added materials and the associated developments. The papers selected demonstrate how innovative scientific research and development is delivering economically viable, real-world solutions for industry by reimagining waste as a resource for the future. These three papers cover analysing above ground resources, simple technique for measuring the elements inside the waste and high temperature transformation of waste.

Disentanglement of random access memory cards to regenerate copper foil: A novel thermo-electrical approach

This paper reports the development of a novel process combining thermal and electrical treatments, which are optimised to provide efficient recovery of copper foil from Random Access Memory cards (RAMs). A primary thermal transformation at 900 °C facilitates a highly efficient recovery of copper foils from RAMs during the secondary processing in the electrical fragmenter, using only 10 pulses at 150 kV. The process yield was 98% and inductively coupled plasma (ICP) analysis showed that the copper foils had 98% purity. X-ray diffraction (XRD) confirmed the presence of copper in a crystalline face-centred cubic (FCC) form. Scanning electron microscopy (SEM) - energy dispersive spectroscopy (EDS) analysis of the foils assisted in understanding the underlying mechanism of electrical separation. Transmission electron microscopy (TEM) gave a new perspective on the regeneration of copper foils wherein new copper grains depicted a ribbon like growth pattern. The copper foils had an electrical conductivity similar to that of commercially available pure copper sheets. Thus, the mechanism of thermo-electrical transformation was studied in detail and regenerated copper foils of high electrical conductivity were afforded from end-of-life RAMs.

Chapter 15 Green Manufacturing: From Waste to Value Added Materials

Abstract Every year, tens of millions of the 1.4 billion cars on the world’s roads are decommissioned. While the ferrous and other metals that constitute about 75% of a vehicle by weight can be readily and profitably recycled, the remaining mix of plastics, glass, composites, complex materials, fragments and contaminants are mainly destined for landfill as automotive shredder residue (ASR). For every car, approximately 100–200 kg of ASR is disposed of in landfill, posing a growing technical and environmental challenge worldwide. The recovery of the ASR for high-end application is the focus of this study, aiming to optimise the use of these valuable resources and minimise the extractive pressure for raw materials, a future green manufacturing, contributing towards a zero waste circular economy. As the dissolution of carbon into iron is a key step in the manufacture of iron-carbon alloys, the feasibility of utilizing the waste polymers within ASR as sources of carbon in different areas of pyrometallurgical processing was investigated. Polypropylene and rubber, in a blend with metallurgical coke, were used as carbonaceous substrates and the slag-foaming phenomenon was investigated via the sessile drop technique in an argon environment at 1,550°C. The results indicated the rubber/coke blend achieved significantly better foaming behaviour, and the PP/coke blend exhibited a moderate improvement in slag foaming, in comparison to 100% metallurgical coke. The overall results indicated the incorporation of ASR had significant improvement in foaminess behaviour, increasing furnace efficiency.

Diffusion Coefficients and Structural Parameters of Molten Slags

This paper presents the results of two experimental studies on diffusion of SiO2 in “silicomanganese” (SiO2-MnO-CaO-Al2O3- MgO) slag and CaO in calcium aluminosilicate slag. The diffusivity of SiO2 was measured in the temperature range of 1400–1550 °C; while the diffusivity of CaO was determined at 1430–1600°C. The effects of additives on the chemical diffusivities of SiO2 and CaO were also examined. Addition of CaO and MnO to the silicomanganese slag increased silica diffusivity, while addition of SiO2 and Al2O3 slowed it down. Addition of TiO2 and MnOx to the aluminosilicate slag increased the diffusivity of CaO, while the addition of SiO2 had a negative effect on the diffusivity of CaO. Analysis of diffusivity in relation to the structure of silicate melts demonstrated a good correlation between diffusion coefficients of SiO2 and CaO and NBO/T (non-bridging oxygen per tetrahedrally coordinated atom).

Waste to Value in Steelmaking

The high temperature environment of steelmaking process, offers sustainable pathways for utilizing chemical reactions to re-purpose waste materials as resources. The use of waste polymeric materials in steelmaking is not only a solution for end-of-life products, which currently impose a serious burden on overstretched landfills but it also results in reduction of resource consumption and energy saving. This paper presents industrial plant results on the effect of the utilization of waste polymeric materials in steelmaking on coke and energy consumption.