Aleks Nikoloski

Coal is commonly used as both fuel and reducing agent in producing synthetic rutile from ilmenite (FeTiO3) via the Becher process, which upgrades ilmenite to high-purity TiO2 (>88%). However, coal-based reduction generates significant carbon waste. This study investigated the effect of adding 1–5% w/w potassium hydroxide (KOH), sodium hydroxide (NaOH), and sodium tetraborate (borax) to coal during ilmenite reduction to improve metallisation and reduce carbon burn-off. Results showed that 1% w/w additives significantly increased metallisation to 96% (KOH), 95% (NaOH), and 93% (borax), compared to 80% without additives, while higher concentrations (3–5% w/w) decreased metallisation. Scanning electron microscopy (SEM)analysis showed cleaner particle surfaces and optimal metallisation at 1% w/w, whereas higher additive levels caused agglomeration or sintering due to elevated silica and alumina activity. Additive type also influenced TiO2 quality, with KOH enhancing TiO2 at low concentrations but causing negative effects at higher levels, while NaOH and borax reduced TiO2 quality via sodium-based compound formation. All additives reduced carbon burn-off, with KOH producing the greatest reduction. The iodine number of the carbon residue increased with higher additive concentrations, with KOH achieving 710 mg/g at 1% w/w and 900 mg/g at 5% w/w, making the residue suitable for water treatment. Overall, KOH is the most effective additive for producing high-quality synthetic rutile while minimising carbon waste.

Microwave fracturing and assisted mechanical breakage offer efficient and cost-effective rock excavation potential. However, these methods have not been well studied or understood for the deployment of in situ recovery (ISR) in mining, which could benefit from microwave-induced cracking to accelerate in situ leaching. This paper reports on investigations into the effects of microwaves on rock transport properties, specifically for in situ recovery applications. The research focused on microwave fragmentation of a synthetic ore with composition and particle size similar to many wet ore-bearing deposits, as well as hard lithium-bearing rock (spodumene) as a natural analogue, to assess changes in porosity and permeability after microwave treatment. The experiments involved exposing samples with varying water content to heating with different microwave energy levels, followed by examining the impact on the induced crack characteristics. All the samples were characterized by a suite of measurements before and after microwave treatment, including scanning electron microscopy (SEM), Nuclear Magnetic Resonance (NMR), nitrogen gas permeameter-porosimeter, and P-wave velocity measurements. The results showed a strong dependence of rock properties after microwave treatment on water content. At high water content (100%), NMR results showed a substantial increase in porosity, by nearly 17% and a dramatic 47-fold rise in permeability, from 0.65 mD to 311 mD. However, the treatment also caused partial melting of the sample, rendering it unsuitable for further testing, including permeability and P-wave velocity. At moderate water content (20%), permeability substantially increased (233–3404%), which was consistent with the observation of multiple cracks in SEM images. These changes led to low P-wave velocity values. This research provides crucial insights into microwave fracturing as a method for in situ recovery in mining.

Different morphologies of cobalt oxide (Co3O4) electrodes were prepared through the electrochemical deposition technique with various electrodeposition times from 10 min to 50 min. Platinum (Pt) nanoparticles were deposited on the Co3O4 electrodes through sputter coating. The crystallographic, microstructural, surface functional, textural–structural, and electric properties of the Co3O4 electrodes were investigated. X-ray diffraction analysis identified a pure cubic Co3O4 crystal structure in the samples. In the electrodeposition process, the microstructure of the electrodes varied from hierarchical 3D flower-like to 2D hexagonal porous nanoplates due to an increase in oxygen vacancies. The carrier densities of all samples were between 5.77 × 1014 cm−3 and 8.77 × 1014 cm−3. The flat band potentials of all samples were between −5.91 V and −6.21 V vs. an absolute electron potential, and the potential values for electrodes became more positive as the oxygen vacancy concentration in the film structure increased. The 2D hexagonal porous nanoplate Pt/Co3O4 electrodes offered the highest oxygen vacancies and thus the maximum current density of 102.66 mA/cm2, with an external potential set at 1.5 V vs. an Ag/AgCl reference electrode.

Redox flow batteries (RFBs) are known for their exceptional attributes, including remarkable energy efficiency of up to 80%, an extended lifespan, safe operation, low environmental contamination concerns, sustainable recyclability, and easy scalability. One of their standout characteristics is the separation of electrolytes into two distinct tanks, isolating them from the electrochemical stack. This unique design allows for the separate design of energy capacity and power, offering a significantly higher level of adaptability and modularity compared to traditional technologies like lithium batteries. RFBs are also an improved technology for storing renewable energy in small or remote communities, benefiting from larger storage capacity, lower maintenance requirements, longer life, and more flexibility in scaling the battery system. However, flow batteries also have disadvantages compared to other energy storage technologies, including a lower energy density and the potential use of expensive or scarce materials. Despite these limitations, the potential benefits of flow batteries in terms of scalability, long cycle life, and cost effectiveness make them a key strategic technology for progressing to net zero. Specifically, in Australia, RFBs are good candidates for storing the increasingly large amount of energy generated from green sources such as photovoltaic panels and wind turbines. Additionally, the geographical distribution of the population around Australia makes large central energy storage economically and logistically difficult, but RFBs can offer a more locally tailored approach to overcome this. This review examines the status of RFBs and the viability of this technology for use in Australia.

Thin films of manganese–nickel–cobalt oxide with graphene (G@MNCO) were deposited on copper foam using electrochemical deposition. NiCo2O4 is the main phase in these films. As the proportion of graphene in the precursor solution increases, the oxygen vacancies in the samples also increase. The microstructure of these samples evolves into hierarchical vertical flake structures. Cyclic voltammetry measurements conducted within the potential range of 0–1.2 V reveal that the electrode with the highest graphene content achieves the highest specific capacitance, approximately 475 F/g. Furthermore, it exhibits excellent cycling durability, maintaining 95.0% of its initial capacitance after 10,000 cycles. The superior electrochemical performance of the graphene-enhanced, manganese-doped nickel–cobalt oxide electrode is attributed to the synergistic contributions of the hierarchical G@MNCO structure, the three-dimensional Cu foam current collector, and the binder-free fabrication process. These features promote quicker electrolyte ion diffusion into the electrode material and ensure robust adhesion of the active materials to the current collector.

This study investigated the effects of different grinding environments on the flotation behaviour of spodumene from lithium pegmatite ore through bench-scale froth flotation tests using sodium oleate (NaOL) collector. The mechanisms governing these interactions were characterized by particle zeta potential measurements, scanning electron microscopy in tandem with energy-dispersive spectroscopy (SEM-EDS) and X-ray Photoelectron Spectroscopy (XPS). Flotation performance was investigated for spodumene wet ground with cast iron and zirconia media under alkaline, acidic and neutral conditions. SEM-EDS analyses revealed marked differences in particle shape between acid and alkali treated samples. Sodium hydroxide treatment induced mild etching and selective surface dissolution, exposing fresh regions, whiles hydrochloric acid treatment caused extensive morphological alterations, including scuffing marks, holes and fine residuals. XPS analysis showed significant difference in surface composition of iron, aluminium, silicon, carbon and oxygen under different treatment conditions. Iron deposition on mineral surface ground with cast iron balls was attributed to the corrosion of media onto the pulp during grinding. At a head grade of 0.67% lithium oxide (Li2O), the highest flotation performance with zirconia grinding assayed as 2.15% Li2O grade and 46% recovery with alkali pretreatment. By contrast, cast iron grinding achieved a higher recovery of 95%, albeit at a lower concentrate grade of 1.72% Li2O. This work highlights the need to tailor activators and depressants for zirconia and cast-iron media, respectively, to optimize spodumene flotation selectivity.

Exfoliated La-doped g-C3N4, namely La(x%)-eCN-N (x = 0.1%– 10%), was prepared via in-situ La doping and thermal treatment. The photocatalytic activity of La(x%)-eCN-N was explored through the degradation of methyl orange (MO) under visible light and then optimized by varying the loading of La dopant. The optimised La(1%)-eCN-N displayed an enhanced photocatalytic performance over the bulk and exfoliated g-C3N4, and bulk La-doped g-C3N4. Meanwhile, the use of La(1%)-eCN-N was seen with a high photocatalytic efficiency towards MO removal when compared with La(1%)-eCN-C, La(1%)-eCN-T, and La(1%)-eCN-U, which were prepared via conventional chemical, thermal and ultrasonic exfoliation of the pre-formed bulk La-doped g-C3N4. The observed outstanding photocatalytic activity of La(1%)-eCN-N was explained by several favourable features. In particular, the thin nanosheets would permit swift migration and effective separation of photogenerated charge carriers. The nitrogen adsorption–desorption analysis revealed an increased surface area and porosity, which might expose more active sites on the photocatalyst surface to adsorption and subsequent photocatalytic removal of MO molecules. Moreover, La(1%)-eCN-N was proven with improved visible light absorption, enhanced charge carrier separation and reduced transfer resistance. Its activity, along with the crystal and chemical characteristics, was largely retained after five cycles of photocatalytic reaction, affirming its good reusability and stability for potential practical application. The key reactive oxidising species involved in the photocatalytic removal of MO using La(1%)-eCN-N was experimentally determined to be the superoxide radical.

In the present study, a series of La-doped g-C3N4 with Ag nanoparticles (NPs) decoration was synthesized via one-pot thermal pyrolysis and wet impregnation. As compared with the bulk g-C3N4 (BCN), La-modified g-C3N4 or Ag-modified g-C3N4, the optimal La-doped g-C3N4 with Ag NPs decoration (Ag-0.8/LaCN-1) showed improved methyl orange (MO) adsorptive capacity and higher photocatalytic activity, because of the synergistic effect of La doping and Ag NPs decoration. Adsorption kinetic and isotherm models were employed to study the adsorption mechanism. The best fit of the experimental data was obtained using the pseudo-second-order (PSO) kinetic model and the Redlich-Peterson isotherm model. It indicated that the MO adsorption using Ag-0.8/LaCN-1 was mainly governed by chemisorption; the process appeared to follow neither an ideal monolayer nor a multilayer but a hybrid mechanism. The MO adsorptive (30 min) removal and photocatalytic degradation (80 min) rate using Ag-0.8/LaCN-1 was seen at around 49.6 and 13.1 times that of BCN, respectively. At pH = 6, the good MO adsorption could be mainly the result of π – π interaction and complexation; whilst the good photocatalytic efficiency was ascribed to improved visible light absorption, charge carrier separation and transfer. Superoxide radicals and holes were proven as the main reactive species for the high MO photocatalytic degradation, by conducting the scavenger test and ESR analysis. The as-prepared Ag-0.8/LaCN-1 displayed good reusability with approximately a 3% loss in the total MO removal % after five consecutive runs of tests. Good stability was observed, recording only ca. 0.25% and 0.01% leaching of Ag and La dopants from Ag-0.8/LaCN-1, respectively, suggesting its robustness for practical use.

The increasing demand for lithium-ion batteries particularly for electric vehicles underscores the importance of improving the sustainability of lithium mining operations. The depletion of high-grade lithium ore deposits has necessitated the upgrading of medium to low-grade ores for lithium extraction. Spodumene is the most commercially exploited lithium-bearing mineral found in pegmatites due to its high lithium content. Ore sorting can be used for early rejection of up to 60% of gangue minerals prior to preconcentration. Dense media separation is a viable spodumene beneficiation method. However, as case studies have shown, flotation may still be required to process middlings and the undersized fraction, which falls outside the particle size range effective for dense media separation. Magnetic separation can be conducted during or after flotation to remove iron impurities in lithium concentrates. While fine particle flotation has historically achieved high recovery rates, their economic feasibility is increasingly questioned due to intensive comminution requirements. Coarse particle flotation in mechanical flotation cells for instance is inefficient due to turbulence-induced detachment of coarse particles. Coarse particle beneficiation using fluidized bed flotation cells can offer advantages such as reduced grind size and environmental footprint. Despite proven energy savings and recovery efficiencies in other mineral sectors, their application in lithium mining operations remains limited to pilot scale. Also, research in this area is underexplored. This review addresses this gap by evaluating the feasibility, potential benefits and challenges of integrating ore sorting, dense media separation, magnetic separation and fluidized bed flotation with the HydroFloat, NovaCell and Reflux cells into lithium ore beneficiation flowsheets. Key challenges identified include high water consumption and the inadvertent entrainment of fine particles requiring desliming steps. Furthermore, this review acknowledges the challenges in spodumene beneficiation due to the structural similarities among silicate minerals and highlights relevant pretreatment methods to improve selectivity, recovery and grade.

This study systematically studied the effects of Pr, Fe, and Na as representative rare earth, transition, and alkali metal dopants, respectively, on the photocatalytic activity of exfoliated graphitic carbon nitride (g-C 3 N 4). The doped exfoliated g-C 3 N 4 samples were prepared by integrating precursor ion intercalation into the pre-formed g-C 3 N 4 with thermal treatment. The as-prepared catalysts were examined for crystal, textural, chemical, optical, and photoelectrochemical properties to explore the correlation between dopants and photocatalytic activity of the resulting composites. The detailed analyses revealed that the Pr-doped g-C 3 N 4 exhibited superior photocatalytic activity in degrading methylene blue under visible light, achieving a ~96% removal in 40 min. This was not only better than the activity of g-C 3 N 4 , but also much higher than that of Na-doped g-C 3 N 4 or Fe-doped g-C 3 N 4. The kinetic rate constant using Pr-doped g-C 3 N 4 was 3.2, 5.1, and 2.0 times greater than that of the g-C 3 N 4 , Fe-doped g-C 3 N 4 , and Na-doped g-C 3 N 4 , respectively. The enhanced performance was attributed to its inherent characteristics after optimal tuning, including good surface area, improved porosity, enhanced visible light absorption, suitable electronic band structure, increased charge carrier density, promoted charge separation, and reduced charge transfer resistance. In addition, the optimized Pr(0.4)g-C 3 N 4 was used to study the photocatalytic removal of methylene blue in detail under conditions with different initial methylene blue concentrations, types of dyes, catalyst dosages, initial solution pH, counter ions, and water matrices. Our results demonstrated the high photocatalytic activity of Pr(0.4)g-C 3 N 4 under varying conditions, including in real wastewater media, which were collected from our local municipal wastewater treatment plant. The observed good reusability and stability after five cycles of photocatalytic degradation test further suggested a promising potential of Pr(0.4)g-C 3 N 4 for practical application in wastewater treatment.