Search Results (20)

A novel strategy has been developed for extracting value-added resources from iron-lean, high-alumina- and -silica-containing red muds (RMs). With little or no recycling, such RMs are generally destined for waste dumps. Detailed results are presented on the carbothermic reduction of 100% RM (29.3 wt.% Fe₂O₃, 22.2 wt.% Al₂O₃, 20.0 wt.% SiO₂, 1.2 wt.% CaO, 12.2 wt.% Na₂O) and its 2:1 blends with Fe₂O₃ and red mill scale (MS). Synthetic graphite was used as the reductant. Carbothermic reduction of RM and blends was carried out in a Tamman resistance furnace at 1650 °C for 20 min in an Ar atmosphere. Reduction residues were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), elemental mapping and X-ray diffraction (XRD). Small amounts of Fe₃Si alloys, alumina, SiC and other oxide-based residuals were detected in the carbothermic residue of 100% RM. A number of large metallic droplets of Fe–Si alloys were observed for RM/Fe₂O₃ blends; no aluminium was detected in these metallic droplets. A clear segregation of alumina was observed as a separate phase. For the RM/red MS blends, a number of metallic Fe–Si droplets were seen embedded in an alumina matrix in the form of a cermet. This study has shown the regeneration of alumina and the formation of alumina-based cermets, Fe–Si alloys and SiC during carbothermic reduction of RM and its blends. This innovative recycling strategy could be used for extracting value-added resources from iron-lean RMs, thereby enhancing process productivity, cost-effectiveness of alumina regeneration, waste utilization and sustainable developments in the field. Full article

Drilling fluids are vital in oil and gas well operations, ensuring borehole stability, cutting removal, and pressure control. However, fluid loss into formations during drilling can compromise formation integrity, alter permeability, and risk groundwater contamination. Water-based drilling fluids (WBDFs) are favored for their environmental and cost-effective benefits but often require additives to address filtration and rheological limitations. This study explored the feasibility of using vegetable waste, including pumpkin peel (PP), courgette peel (CP), and butternut squash peel (BSP) in fine (75 μm) and very fine (10 μm) particle sizes as biodegradable WBDF additives. Waste vegetable peels were processed using ball milling and characterized via FTIR, TGA, and EDX. WBDFs, prepared per API SPEC 13A with 3 wt% of added additives, were tested for rheological and filtration properties. Results highlighted that very fine pumpkin peel powder (PP_10) was the most effective additive, reducing fluid loss and filter cake thickness by 43.5% and 50%, respectively. PP_10 WBDF maintained mud density, achieved a pH of 10.52 (preventing corrosion), and enhanced rheological properties, including a 50% rise in plastic viscosity and a 44.2% increase in gel strength. These findings demonstrate the remarkable potential of biodegradable vegetable peels as sustainable WBDF additives. Full article

The present study developed a novel approach for transforming red mud (RM) into soft magnetic materials (SMMs) for applications in advanced electrical devices in the form of Fe-Si and Fe-Si-Al alloys. A total of ten blends were prepared based on two RMs, three iron oxide additives (Fe₂O₃, black and red mill scales), alumina and carbonaceous reductants in a range of proportions. Carbothermic reduction of the blends was carried out in a vertical Tamman resistance furnace at 1600–1650 °C for 30 min in an argon atmosphere; synthetic graphite was used as a reductant. Reaction products were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray fluorescence (XRF) and X-ray diffraction (XRD). Significant amounts of Fe-rich metallic droplets/regions of different grain sizes (0.5 to 500 μm) were produced in these studies. The formation of Fe-Si alloys with Si contents from 3.9 to 6.7 wt.% was achieved in 8 out of 10 blends; the optimal levels of Si for SMMs ranged from 3.2 to 6.5 wt.%. There was clear evidence for the formation of Fe-Si-Al (up to 1.8 wt.% Al) alloys in 4 out of 10 blends. In addition to lowering operating challenges associated with RM processing, blending of RMs with iron oxide additives and alumina presents a novel recycling approach for converting RMs into valuable SMMs for possible emerging applications in renewable energy, storage, electrical vehicles and other fields. Along with reducing RM stockpiles across the globe, this approach is expected to improve resource efficiency, mitigating environmental impacts while generating economic benefits. Full article

The sugar industry must be managed in a manner that encourages innovation with regard to the waste generated throughout the process. The organic load of sugar mill waste is high, as is its potential to pollute water bodies at various stages of the production process, including cooling bearings, mills, sugar cane washing, bagasse waste and cleaning products. It is therefore necessary to identify treatment mechanisms that not only reduce this waste but also return purer water to the environment, combining the reuse of water in various applications. The objective of this study was to analyze the results of the physical and chemical properties of the effluents generated and the principal treatment technologies employed for the remediation of industrial wastewater from sugar factories. The wastewater from Mozambique’s sugar mills has high levels of dissolved or suspended solids, organic matter, pressed mud, bagasse and atmospheric pollutants. The BOD/COD ratio is low (<2.5), indicating the need for secondary treatment or, more specifically, biological treatment. This can be achieved through humid systems built from stabilization ponds, with the resulting water suitable for reuse in agricultural irrigation. In this work, an educational proposal has been developed for engineering students where they learn to calculate and optimize, among other parameters, the natural wastewater treatment and compare it with a conventional wastewater treatment. Full article

Historical buildings have inhabited every epoch of history. Some of these built legacies are now in ruins and dying whilst others are somewhat undamaged. Knowledge of conservation techniques available today has allowed us to understand more innovative ways of conserving the built heritage. Such techniques are, however, incompatible with the building materials available in our historical epoch and environment. People seek to reclaim the forgotten cultural heritage in the midst of the heritage conservation era while bearing in mind that previous work seldom takes into account the inventive preservation methods of today. This study aims to explore the innovative built heritage conservation practice in the Kano metropolis, to detect deterioration and incorporate traditional wisdom and contemporary innovation according to modern urban development. The study adopted qualitative research with a descriptive approach. The descriptive research explains, examines, and interprets prevailing practices, existing situations, attitudes, reasons, and on-going processes, while the qualitative research approach uses spatial analysis methods (direct assessment of physical characteristics of the selected buildings) and focus group discussion (FGD) sessions with the custodians, prominent elderly persons, or ward head (Mai Unguwa) from each of the selected buildings. In this work, we found it necessary to survey 29 historical buildings of which three of the historic buildings from pre-colonial, colonial, and post-colonial architecture were purposively sampled for inclusion. This is on the basis of their value formation, processes, phenomena, and typology. The findings reveal that deterioration is due to decaying plaster and paint, moist walls, deformed openings, sagging roofs, wall cracks, roof leakages, exit spouts, stains, and corrosion. Other factors include microbes and termite attacks, inappropriate use and neglect, civilization, and inappropriate funding. Conservation was performed to avert the amount of decay while the techniques in practice are documentation methods and treatment interventions with no implementation of diagnostic methods. It further unveils the potential benefits of local treatment, as evidenced by the intervention at the Dorayi palace segment, the use of “makuba” (milled locust bean pod) to stabilize the geotechnical performance of “tubali” (local mud bricks) to improve its potency. This milled locust bean pod also serves as the water repellent consolidant in “laso” (local) plaster, which has proven to be eco-friendly, non-toxic, and effective in wall rendering. The need for immediate implementation of diagnosis techniques in the conservation of architectural heritage in the municipality and elsewhere in Nigeria and beyond is eminent. Intervention and implementation of policies, appropriate funding, and mobilization, raising awareness and sensitization on the value, significance, and state of affairs of our cultural heritage is also paramount. Full article

Sugarcane is a lignocellulosic crop which is used to produce sugar in sugarcane processing industries. Globally, sugarcane processing industries generate solid and liquid wastes amounting to more than 279 million tons per annum and by-products; namely, trash, bagasse, mill mud, and molasses. The valorisation of waste and by-products has recently increased and is playing a significant role in achieving policies and goals associated with circular bioeconomy and sustainable development. For the valorisation of sugarcane processing industry waste and by-products, a number of technologies are well established and in use, while other innovative technologies are still ongoing through research and development with promising futures. These by-products obtained from sugarcane processing industries can be converted into biofuels like hydrogen and methane via anaerobic digestion. Molasses belongs to the first-generation (1G) waste, while trash, bagasse, and mill mud belong to second-generation (2G) waste. Various studies have been carried out in converting both first- and second-generation sugarcane processing industry wastes into renewable energy, exploiting anaerobic digestion (AD) and dark fermentation (DF). This review emphasises the various factors affecting the AD and DF of 1G and 2G sugarcane processing industry wastes. It also critically addresses the feasibility and challenges of operating a two-stage anaerobic digestion process for hydrogen and methane production from these wastes. Full article

Combined paper mill biosolids (PB) and forest-derived liming by-products improve soil properties, but their residual effects following several years of application have hardly been investigated. A 13-year (2009–2021) field study was initiated at Yamachiche, QC, Canada, to assess the residual effects of PB and liming materials on the properties of a loamy soil. The PB was applied during nine consecutive years (2000–2008) at 0, 30, 60, and 90 Mg wet·ha⁻¹, whereas the 30 Mg PB·ha⁻¹ rate also received one of three liming materials (calcitic lime, lime mud, wood ash) at 3 Mg wet·ha⁻¹. No amendment was applied during residual years. Past liming materials continued to increase soil pH but their effect decreased over time; meanwhile, past PB applications caused a low increase in residual soil NO₃-N. Soil total C, which represented 40% of added organic C when PB applications ceased, stabilized to 15% after six years. Soil Mehlich-3-extractable contents declined over the thirteen residual years to be not significant for P, K, and Cu, while they reached half the values of the application years for Zn and Cd. Conversely, Mehlich-3 Ca was little affected by time. Therefore, land PB and liming material applications benefited soil properties several years after their cessation. Full article

Red mud desulfurization is an environmentally friendly desulfurization technology. After desulfurization, the acidity of red mud slurry continues to be neutralized for processing new red mud, and no waste acid is generated. At present, there is a lack of research on desulfurization intensification in external fields, etc. To further enhance red mud desulfurization, this paper used an SO₂ detector, X-ray fluorescence spectrometer (XRF), and scanning electron microscope (SEM) to compare and analyze red mud desulfurization under the action of ball mill and ultrasonic external fields. In this study, experiments were conducted using a bubbling and stirring reactor device. The results showed that the suitable red mud slurry concentration was 10 g/L. The raw red mud desulfurization (without external field condition) could reach 100% absorption in the first 25 min, and the desulfurization rate dropped to 81.3% at 80 min. The mechanism of red mud desulfurization was investigated by X-ray diffractometer (XRD), XRF, and infrared spectroscopy. Under the action of the external field of the ball mill, the red mud particles could be refined to prolong the desulfurization time. The red mud after ball milling could reach 100% absorption within 33 min. Under the thermal effect of the ultrasound, 100% absorption could only be achieved within 23 min. From the desulfurization effect and XRF results, it was found that the ball mill was more suitable for promoting red mud desulfurization in the bubbling and stirring reactor. Full article

Extracting nutraceuticals with high value from bagasse, filter mud, and sugarcane leaves discarded as sugar mill by-products, is crucial for the development of a sustainable bio-economy. These by-products are important sources of policosanols and phytosterols, which have a cholesterol-lowering effect. This research focused on using a promising green technology, subcritical liquefied dimethyl ether extraction, with a low pressure of 0.8 MPa, to extract policosanols and phytosterols and on application of pretreatments to increase their contents. For direct extraction by subcritical liquefied dimethyl ether without sample pretreatment, the highest extraction yield (7.4%) and policosanol content were found in sugarcane leaves at 2888 mg/100 g, while the highest and lowest phytosterol contents were found in filter mud at 20,878.75 mg/100 g and sugarcane leaves at 10,147.75 mg/100 g, respectively. Pretreatment of filter mud by ultrasonication in hexane solution together with transesterification before the second subcritical liquefied dimethyl ether extraction successfully increased the policosanol content, with an extract purity of 60%, but failed to increase the phytosterol content. Full article

Semi-autogenous (SAG) mills are widely used grinding equipment, but some ore with critical particle sizes cannot be effectively processed by SAG mills and turned into pebbles. This research aims to analyze and compare the properties of raw ore and pebbles from a zinc- and tin-bearing ore. The results show that the contents of sphalerite, cassiterite, biotite, antigorite, pyroxferroite, ferroactinolite, and ilvaite in the raw ore are higher than those in the pebbles, and that the pebbles have higher contents of hedenbergite, chlorite, epidote, actinolite, etc. Meanwhile, the abrasion and impact resistance of pebbles is greater than that of the raw ore. In addition, the sphalerite is evenly embedded, and the grinding process is regular. Fine cassiterite associated with harder minerals is difficult to dissociate; it is often found in softer or brittle minerals which may be easily ground into ore mud. The cassiterite in the pebbles is associated with hard and brittle hedenbergite and soft chlorite, making it difficult to recover. This research provides a good foundation for evaluating the recovery value of pebbles and improving the productivity of the SAG process. Full article

Bauxite residue (red mud) generated during alumina production is a highly alkaline solid waste. The red mud is mainly stored on land, but it can cause harm to the surrounding environment and human health. The transformation of red mud into soil is a feasible method for the large-scale disposal of red mud, but alkali removal is the key process that controls the transformation of red mud into soil. In this study, the calcification dealkalization of red mud with a small particle size was carried out below 100 °C. The results show that the sodium in red mud is predominately distributed in small particles, mainly because the lattice alkali and alkali present between the crystals are exposed to the surface of red mud particles by ball milling. The dealkalization process was controlled by the internal diffusion of the shrinking-core model (SCM), and the apparent activation energy was 23.55 kJ/mol. The dealkalization rate and the Na₂O content of dealkalized red mud reached 92.44% and 0.61%, respectively. The dealkalization rate increased with increasing reaction time, reactant concentration, and leaching temperature, and this result was consistent with the results of the kinetic study. In addition, calcification enhances the flocculation of particles, so the filtration performance of red mud improved. Full article

Wastewaters from the olive oil industry are a regional environmental problem. Their phenolic content provides inherent toxicity, which reduces the treatment potential of conventional biological systems. In this study, Sulfate Radical based Advanced Oxidation Processes (SRbAOPs) are compared with advanced oxidation processes (namely Fenton’s peroxidation) as a depuration alternative. Synthetic olive mill wastewaters were submitted to homogeneous and heterogeneous SRbAOPs using iron sulfate and solid catalysts (red mud and Fe-Ce-O) as the source of iron (II). The homogenous process was optimized by testing different pH values, as well as iron and persulfate loads. At the best conditions (pH 5, 300 mg/L of iron and 600 mg/L of persulfate), it was possible to achieve 39%, 63% and 37% COD, phenolic compounds and TOC removal, respectively. The catalytic potential of a waste (red mud) and a laboratory material (Fe-Ce-O) was tested using heterogenous SRbAOPs. The best performance was achieved by Fe-Ce-O, with an optimal load of 1600 mg/L. At these conditions, 27%, 55% and 5% COD, phenolic compounds and TOC removal were obtained, respectively. Toxicity tests on A. fischeri and L. sativum showed no improvements in toxicity from the treated solutions when compared with the original one. Thus, SRbAOPs use a suitable technology for synthetic OMW. Full article

At present, the world is committed to the development of environmentally friendly, sustainable and industrial safety. The effective treatment of industrial solid waste can be applied in the field of industrial safety. It is one of the ways to apply industrial solid waste to industrial safety to modify industrial solid waste and combine active powder to prepare industrial solid waste-based composite powder explosion inhibitors and apply it to underground coal dust explosion. This paper introduces the modification and preparation methods of industrial solid waste, and analyzes the good explosion suppression effect and good economic benefit of industrial solid waste-based composite powder explosion inhibitors on coal dust explosion. In this paper, four kinds of industrial solid wastes (red mud, slag, fly ash and sludge) were modified, and the modified solid waste materials with good carrier characteristics were obtained. Combined with a variety of active powders (NaHCO₃, KH₂PO₄ and Al(OH)₃), the industrial solid waste-based composite powder explosion inhibitors were obtained by solvent-crystallization (WCSC) and dry coating by ball milling (DCBM). Those kinds of explosion inhibitors can suppress the explosion of pulverized coal in 40–50% of cases. Compared with the powder explosion inhibitor commonly used in industry, it has a lower production cost and better explosion suppression effect. Those kinds of explosion inhibitors have a good industrial application prospect. Full article

There are four main waste products produced during the harvesting and milling process of sugarcane: cane trash, molasses, bagasse and mill mud–boiler ash mixture. This study investigates the value proposition of different techniques currently not being adopted by the industry in the utilisation of these wastes. The study addresses the technical challenges and the environmental impact associated with these wastes and comes up with some recommendations based on the recent findings in the literature. All the biomass wastes such as bagasse, trash (tops) and trash (leaves) have shown great potential in generating higher revenue by converting them to renewable energy than burning them (wet or dry). However, the energy content in the products from all the utilisation methods is less than the energy content of the raw product. This study has found that the most profitable and challenging choice is producing ethanol or ethanol/biogas from these wastes. The authors recommend conducting more research in this field in order to help the sugar industry to compete in the international market. Full article

In this study, CaO-containing wastes from pulp and paper industries such as fly ash (FA) and calcined lime mud (LM) were utilized to neutralize and purify acidic wastewaters from the pickling processes in steel mills. The investigations were conducted by laboratory scale trials using four different batches of wastewaters and additions of two types of CaO-containing waste materials. Primary lime (PL), which is usually used for the neutralization, was also tested in the same experimental set up in the sake of comparison. The results show that these secondary lime sources can effectively increase the pH of the acidic wastewaters as good as the commonly used primary lime. Therefore, these secondary lime sources could be potential candidates for application in neutralization processes of industrial acidic wastewater treatment. Moreover, concentrations of metals (such as Cr, Fe, Ni, Mo and Zn) can decrease dramatically after neutralization by using secondary lime. The LM has a purification effect from the given metals, similar to the PL. Application of fly ash and calcined lime mud as neutralizing agents can reduce the amount of waste from pulp and paper mills sent to landfill and decrease the need for nature lime materials in the steel industry. Full article