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• Abrasion resistance of near-matched blast furnace bosh and feed cokes was examined. • High temperature abrasion resistance of cokes was lower than that at room temperature. • Differences in abrasive wear between RMDC and IMDC were observed for the bosh coke. • Difference in RMDC and IMDC wear decreased with increasing severity of conditions. • Tribochemical wear of IMDC was observed during in-situ testing in a CO 2 atmosphere. In this second in a series of two papers, the results of tribological testing of surfaces of coke samples retrieved from an operating blast furnace were compared with those of the corresponding feed coke, to assess the impact of the conditions in the blast furnace on the abrasion resistance of coke. Tribological tests were carried out at temperatures of up to 950 °C under a controlled inert (argon) or reactive (CO 2) atmosphere. Coke wear characteristics were quantified via (i) analysis of the coefficient of friction (COF) during tribological testing, and (ii) the application of microscopy and imaging techniques to the abraded specimens. The blast furnace coke sample was from the underside of the cohesive zone and is referred to as bosh coke in this paper. A near-matched feed coke was also examined. Under ambient testing conditions, the bosh coke had a lower abrasion resistance than the unreacted feed coke samples, indicating that the conditions coke is subjected to during its descent in the blast furnace effectively reduces its resistance to abrasion. Increasing the measurement temperature to 950 °C lowered the abrasion resistance of both the reactive maceral derived components (RMDC) and the inertinite maceral derived components (IMDC) in both samples. The bosh coke RMDC showed more severe damage than the IMDC, using a subjective damage severity scale. The difference in damage severity between these two phases in the bosh coke was reduced as the severity of the tribological testing conditions increased from ambient to elevated temperature (950 °C) to a reactive CO 2 environment. Feed coke samples that had been pre-reacted with CO 2 displayed a mean COF over time trend that was similar to that obtained from the bosh coke samples. During in-situ testing in a CO 2 environment, tribo-chemical wear of the IMDC was detected, due to the surface of the IMDC reacting with the CO 2 in the atmosphere. The observed tribo-chemical wear was due to the indenter and the coke surface rubbing against each other in this CO 2 environment, resulting in the continuous formation and removal of reaction products. Similar trends in COF over time were observed for the bosh and feed cokes during in-situ reaction with CO 2. The substantial decrease in abrasion resistance in coke at high temperature suggests that abrasion may be a more significant degradation pathway for coke in the blast furnace than hitherto expected. [ABSTRACT FROM AUTHOR]

• In-situ abrasion resistance of cokes was examined at elevated temperatures. • Tests were carried out in a controlled gas atmosphere (reactive (CO 2) or inert). • Abrasion resistance decreased with increase in temperature, even at 400 °C. • Difference between room and high temperature test results depended on parent coals. • Wear severity was quantified using a combination of image analysis techniques. A novel approach was developed to examine coke abrasion resistance in-situ at temperatures of up to 950 °C and in a controlled gas atmosphere using rotational tribological testing. The originality of this approach lay in the ability to apply tribological testing to the porous coke surface at elevated temperatures under a controlled inert or CO 2 reactive atmosphere. Coke wear characteristics were quantified via (i) the application of advanced microscopy and image analysis techniques, and (ii) analysis of the coefficient of friction (COF) during tribological testing. Two pilot oven cokes were examined in this study, which were generated from single coking coals of similar rank but different petrographic composition. The cokes tested showed a deterioration in abrasion resistance even at 400 °C, and this was accentuated at 950 °C. The COF and the severity of the wear as a function of temperature and gas atmosphere were markedly different between the two cokes. Coke C396 from a mid-to-low vol, medium vitrinite coal showed no statistically significant differences between the wear severity results recorded following room temperature testing and high temperature testing in a CO 2 environment. Conversely, the more reactive coke C426 with a higher parent coal inertinite content showed clear differences in the extent of abrasive wear at room temperature and at high temperature in both inert and reactive gas atmospheres. This suggests that the reduction in abrasion resistance at elevated temperatures is accentuated in the coke with the highest coke reactivity index (CRI) and the highest content of inertinite maceral derived components (IMDC). Our research has shown that at room temperature, the IMDC show greater resistance to abrasion than the reactive maceral derived components (RMDC). This has implications for understanding the relevance of room temperature testing to the abrasion resistance of coke under practical blast furnace operation conditions. For example, a coke from a coal or blend with a comparatively high inertinite content may show lower resistance to abrasion in the blast furnace than would be expected from tumble drum indices. Larger sample numbers and cokes from a variety of single coals need to be tested in further work to verify these assertions. Finally, a novel method using micro-CT image analysis was developed to examine the wear path generated at the coke surface during tribological testing. The purpose of this was to assess the extent of the abrasive wear by comparing the rendered micro-CT images before and after tribological testing. A colour gradient scale was used to facilitate the quantitative assessment, whereby the colour of each voxel was based on the distance from the nearest voxel that is associated with solid phase. As expected, the specific surface area (SSA) calculated for the upper 1 mm of each sample decreased following tribological testing due to the generation of a wear track which is smoother than the initially rough, porous coke surface. In the C426 coke type examined, the SSA decreased the most for the sample tested in an argon atmosphere at 950 °C, matching the COF and quantified wear severity results, which showed there was a notable increase in abrasive wear to this coke as the temperature was raised from room to elevated temperature. Coupling this method of analysis with 3D visualisation techniques in further work would provide a powerful approach to examine and quantify mechanisms of coke surface breakage and the microstructural and/or microtextural features responsible for the breakage. [ABSTRACT FROM AUTHOR]

Coke samples, produced from coals having a range of rank and vitrinite content, were subjected to uniaxial loading in a universal tester. Cokes were also imaged at high resolution using micro-CT. The aim was to understand the relationship between the internal microstructure of the coke and coke strength under load. The loading was done in two separate ways, being either compression to failure or progressive loading. The results showed that the coke samples underwent a form of stiffening at low loads, potentially due to closing of fine-scale pores and/or re-alignment of graphitic layers in the RMDC. Measurements of plastic strain indicated that these changes were permanent. At higher loads, small load-bearing components of the microstructure were found to break, leading to a softening of the coke samples. Evidence of the breaking was observed using micro-CT images before and after loading of samples. The work has relevance to the understanding of the fundamentals of coke strength, as well as to issues relating to handling and preparation of coke for standard testing. [ABSTRACT FROM AUTHOR]

Acoustic emission profiles generated during scratch testing of a range of metallurgical coke samples were recorded and linked to the concurrent energy release, dispersal or absorption on coke fracture or damage. Three different signatures were identified, which were based on the simultaneous measurement of acoustic and total energy release profiles, and these signatures could be correlated with both the microstructure and microtexture of the coke being traversed at the time. The acoustic emission signature for fracture or damage to the coke reactive maceral derived constituents (RMDC) was correlated to the rank of the parent coal or coal blend, with the signature number generally increasing with increasing rank. Conversely, the signature numbers did not vary with parent coal rank for fracture or damage to the inertinite maceral derived constituents (IMDC), with the majority of IMDC fractures associated with a release of mechanical energy. The incidence of the signature associated with a release of mechanical energy (type 1) became increasingly dominant from RMDC to RMDC-IMDC interfaces to IMDC. Conversely, signature types associated with a dispersal (type 2) or absorption (type 3) of mechanical energy become increasingly dominant from IMDC to RMDC-IMDC interfaces to RMDC. The findings suggest acoustic emissions recorded during scratch testing and their subsequent characterisation can be used to indicate the fracture toughness of a given coke. This study contributes towards a broader program of research to improve understanding of the factors which influence the strength of coke and its microtextural constituents and interfaces, and how this relates to the properties of the parent coals. [ABSTRACT FROM AUTHOR]

Petrographic analysis of coke samples from the tuyere level of an operating blast furnace was carried out using a combination of advanced microscopy techniques including high resolution bireflectance and maximum reflectance measurements. A novel tribological approach was employed to investigate the wear mechanisms of the same cokes. The study showed that the wear mechanisms of coke are influenced by its microstructure and microtexture, as well as the strength and nature of the interfaces between the different coke textural constituents. The wear mechanisms of the cokes were found to vary with location from the tuyere entrance of the blast furnace and also differed to the feed coke. This is the first example of the application of petrographic analysis of cokes from an operating blast furnace to identify the difference in hardness and interaction strength of the distinct coke textural constituents. This research contributes towards improving understanding of the complex mechanisms of coke degradation in operating blast furnaces. [ABSTRACT FROM AUTHOR]

Micro-CT imaging of samples of metallurgical coke was achieved at high resolution (~ 10 μm), using the Imaging and Medical Beamline of the Australian Synchrotron. The coke samples were then stressed to breaking point and imaged again. The result is that we can examine, in fine detail in 3D, the locations of the fracture surfaces in the coke, and their relationship to the different aspects of the microstructure. In addition, we have performed 3D finite element linear elasticity analysis, using the microstructure of the cokes as input to the calculations. The result is a 3D map of the von Mises stress in the structure, which provides information about the likely locations of fracture. Finally, we have performed a fractographic analysis of the fracture surfaces, in order to characterise the nature of the fracture mechanisms. The imaging and analysis has been performed for both compressive and mixed-mode loading of the coke samples. The work provides the opportunity to identify the key mechanisms for fracturing of coke due to the aspects of their microstructure, and has the potential to aid in the production of stronger metallurgical coke, by means of blending coals to produce coke with improved strength properties. [ABSTRACT FROM AUTHOR]

Metallurgical coke is a complex brittle heterogeneous material consisting of carbon derived from fusible, semi-fusible and inert coal particles that forms a porous composite matrix. This paper presents a novel approach to assess and quantify the breakage behaviour and microstructural weaknesses in a pilot oven metallurgical coke. The approach uses fractography, a method commonly applied to determine the fracture behaviour and origin(s) in homogeneous materials, such as metals and ceramics. Determination of the fracture origin(s), paths of crack propagation and microstructural weaknesses in such a complex heterogeneous material as metallurgical coke represents a significant advance in both the application of fractography and the assessment of coke strength and breakage behaviour. Identification of the key features that contribute to the coke’s failure will facilitate better prediction of coke strength from coal properties and ultimately optimisation of the coal blending process. Key features and markings have been clearly identified on fracture surfaces that can either be traced back to the fracture origin or give an indication of the type of fracture or stresses to which the coke has been subjected, including the directionality and strength of those stresses. These markings include hackle, hackle twist and wallner lines, as well as markings generated by conchoidal and overload fractures. A three-step approach was applied to determine the breakage behaviour in stabilized lumps of the pilot oven coke, in which fractured coke surfaces were analysed at the macro, micro and submicron levels. The observed mechanisms of failure were quantified and summarised using a radar diagram. [ABSTRACT FROM AUTHOR]

Metallurgical coke samples across the tuyere level of an operating blast furnace were analysed using a fractographic approach to identify and quantify various coke failure mechanisms. Tuyere level cokes displayed different failure mechanisms compared to the feed coke, implying a strong influence of the blast furnace reaction environment on the modification of coke failure mechanisms. The conchoidal and brittle overload type failures were noted to have an effect on the propagation of transgranular and intergranular crack growth in the coke microstructure. Feed coke breakage behaviour was strongly influenced by existing fissures and conchoidal fracture, while the breakage of the deadman coke lumps was dominated by pore wall collapse through intergranular crack growth in combination with erosive wear. The porosity at the IMDC–RMDC interface in coke has been identified as a critical parameter contributing to coke failure at tuyere regions. This fractographic study demonstrates that the fracture faces show evidence of the varying failure mechanisms presented in the preceding manuscripts (Part 1 and Part 2), in addition to the erosive wear resulting from the blast furnace exposure. However, further studies are required to establish the association between the identified coke failure mechanisms and coke texture, which has implications for improving coke performance in a blast furnace. [ABSTRACT FROM AUTHOR]

Metallurgical coke used in blast furnaces is the result of blending coals to achieve the optimum coke strength properties. Prediction of coke strength from coal properties relies primarily on statistical methods. Improvement of these models is desirable. We believe a better understanding of the fundamental factors controlling coke strength is required to achieve this. In this second of a series of three papers, we apply our recently developed fractographic approach to examine and quantify the breakage behaviour and microstructural weaknesses in pilot oven metallurgical cokes from two series of single coals and binary blends of the coals. We have successfully applied fractography to perform an effective failure analysis of the complex, heterogeneous coke material. Summaries of the factors contributing to the failure of each coke studied have been presented as radar graphs. These graphs demonstrate that the failure profile of the cokes from blends is not simply a weighted average of the fracture behaviour of the cokes from the constituent single coals. Instead, non-additive effects are observed, and this may have implications for the mathematical models widely used to predict coke behaviour and strength in the blast furnace. Trends between the various fractographic parameters have been identified, and preliminary relation of these to both the maximum compressive strength of each coke and basic properties of the original coals, has been completed. Enhanced understanding of how the fracture behaviour of each coke relates to the properties of the coal blend used will help facilitate better prediction of coke strength from coal properties and ultimately optimisation of the coal blending process. [ABSTRACT FROM AUTHOR]

Compartmentalization, i.e. the ability to create controlled volumes and separate molecules one from another is possibly the most important requisite for complex manipulations. Indeed, compartmentalization has been the first step to isolate the building blocks of life and ensure the dynamic nature that today makes the complexity of any living system. For decades scientists have tried using many synthetic approaches to imitate such ability and one the most successful comes from mimicking the biological component responsible for the compartmentalization: the phospholipid. We are now able to synthesize macromolecular analogues of the phospholipid using advanced co-polymerization techniques. Copolymers that comprise hydrophilic and hydrophobic components (i.e. amphiphilic) can be designed to self assemble into membrane enclosed structures. The simplest of those is represented by a sac resulting from the enclosure of a membrane into a sphere: the vesicle. Vesicles made of amphiphilic copolymers are commonly known as polymersomes and are now one of the most important nanotechnological tool for many applications spanning from drug delivery, gene therapy, medical imaging, electronics and nanoreactors. Herein we review the molecular properties, the fabrication processes and the most important applications of polymersomes. [ABSTRACT FROM AUTHOR]

The steel industry is one of the largest industrial carbon dioxide emitters, accounting for up to 7% of global emissions. Increasingly stringent global carbon emission regulations are prompting the steel and coal industries to explore and implement carbon abatement strategies through both the incremental development of current technologies and the incorporation of new, innovative ones. This paper reviews the current status and future development of sustainable cokemaking, aiming to identify suitable carbonaceous materials for partial coal displacement in metallurgical coking blends and the desirable properties of coals which facilitate such displacements. Results from works pertaining to the influence of renewable and waste additions on the thermoplastic properties of coal blends and the quality of resulting cokes are included. This includes the mechanism of interaction between various additives and metallurgical coal and the influence on the coking behavior, microstructural and microtextural transformation, and ash chemistry during cokemaking. The sustainability of incorporating certain carbonaceous additives in blends on a commercial scale has also been evaluated. Efforts were made to draw correlations from literature data regarding the impact of coal property parameters on the carrying capacity of coal in blends with renewable biomass feedstocks and other waste additives. The review has identified the knowledge gaps and future research needs in sustainable cokemaking. • Influences of renewable additives for cokemaking are reviewed. • Promising carbonaceous materials for partial coal displacement in coking blends were analysed. • The significance of coal properties on coal carrying capacity was explored. • The knowledge gaps and future research needs in sustainable cokemaking were identified. [ABSTRACT FROM AUTHOR]

• Measures for reducing the carbon intensity of blast furnace ironmaking were introduced. • Influences of low-carbon ironmaking processes on fuel requirements are reviewed. • The introduction of alternative reductants cannot eliminate the need for metallurgical coke. • Sustainability of blast furnace ironmaking depends on improving the H/C replacement ratio. • Introduction of hydrogen promotes the solution loss and structural degradation of coke. The blast furnace technology is still the main ironmaking route with a current global share of 70%. Reduction of fossil carbon consumption and CO 2 emissions in blast furnace operations are essential for the decarbonization of steelmaking. Potential solutions such as introducing renewable carbon-based materials (torrefied biomass, charcoal), using hydrogen-enriched reducing gases (i.e., hydrogen gas, coke oven gas, reformed coke oven gas, green methane), oxygen enrichment with top gas recycling, and carbon capture and storage/utilization have been considered to decrease emissions. The enhanced sustainability of blast furnace operations depends primarily on improving the hydrogen-to-carbon replacement ratio. Hydrogen is an effective reducing agent, producing steam during the reduction of ferrous burden. The replacement of coke and PCI with hydrogen leads to reduced fuel rates and CO 2 emissions. Although implementing the innovative ironmaking solutions reduces coke and coal consumption, coke cannot be replaced entirely as it plays an irreplaceable role as a mechanical support network and the permeable layer for gas movement in the blast furnace. The injection of alternative reducing agents into the blast furnace alters the reaction environment by changing gas composition and temperature. Therefore, understanding the impacts of new reaction conditions on coke rate and quality requirements is important to both coal producers and steel manufacturers. This paper reviews the current understanding of how the introduction of alternative reducing agents into the blast furnace influences the gasification behavior, degradation mechanism, and consumption rate of coke. The review also identifies the knowledge gaps and future research opportunities in the field. [ABSTRACT FROM AUTHOR]

Abstract: Membrane fouling is one of the most important challenges in reverse osmosis operation. In this study, low-fouling, poly(ethylene glycol) (PEG) acrylate multilayers were assembled via the layer-by-layer technique on a commercial polyamide reverse osmosis membrane and stabilized using click chemistry. Resistance to fouling of the membrane surface with a model biopolymer increased as the number of PEG bilayers was increased. This trend was consistent with the measured surface contact angles of the membranes and with scanning electron microscopy images before and after fouling experiments. Importantly, the flux through unfouled membranes fell only marginally (9–17%) due to the presence of the multilayer coating. AFM images of the coated and uncoated membranes showed little change in surface roughness, supporting the hypothesis that the coating layer is of thickness in the nanometer range. This coating strategy holds promise for the preparation of membranes that are both high in flux and resistant to fouling. [Copyright &y& Elsevier]