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17 pages, 7034 KiB

Open AccessArticle

Bioleaching of Valuable Elements from Red Mud: A Study on the Potential of Non-Enriched Biomass

by Anna Cozzolino, Giovanna Cappai, Stefano Cara, Stefano Milia, Riccardo Ardu, Elena Tamburini and Alessandra Carucci

Minerals 2023, 13(7), 856; https://doi.org/10.3390/min13070856 - 24 Jun 2023

Cited by 1 | Viewed by 1244

Abstract

Red mud (RM) is the main residue produced by the alkaline extraction of alumina (Al₂O₃) from bauxite, and it contains valuable metals such as iron (Fe), aluminium (Al), titanium (Ti), magnesium (Mg), manganese (Mn), rare earth elements, etc. This [...] Read more.

Red mud (RM) is the main residue produced by the alkaline extraction of alumina (Al₂O₃) from bauxite, and it contains valuable metals such as iron (Fe), aluminium (Al), titanium (Ti), magnesium (Mg), manganese (Mn), rare earth elements, etc. This research aimed to investigate the biologically induced leaching of some valuable elements from raw RM without preliminary biomass enrichment and inoculum, simultaneously reducing RM polluting potential and extracting metals for their subsequent recovery within a circular economy-based approach. In addition to the missing inoculum, such an approach is challenging since high RM alkalinity and pH, as well as the absence of any sulphides, constrain the use of the most common biohydrometallurgical techniques. Red Muds from two European locations were tested (RM-I and RM-II, respectively). Bioleaching tests were performed at different temperatures (T = 22 °C and 28 °C; and also 15 °C for RM-II) and solid-to-liquid ratios (S/L = 2%, 5%). A sudden drop in pH from alkaline to constant neutral/acidic values was observed in almost all tests, and such results were attributed to biological activity since abiotic tests did not show any pH decrease. The best results in terms of extraction were achieved with RM-II, in particular for Al, Mg and Mn (17%, 42% and 47%, respectively). At 2% S/L, the highest temperature allowed for a better metal release, while at 5% S/L, the highest extraction of Al, Mg and Ti was observed at 22 °C. As expected, iron was less available to leach at the achieved pH values, as it was mostly present as hematite in both RMs. Finally, the first microbiological characterisation of the autochthonous biomass selected during the bioleaching treatment of RM was provided. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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18 pages, 12670 KiB

Open AccessArticle

Remote Sensing and Mycorrhizal-Assisted Phytoremediation for the Management of Mining Waste: Opportunities and Challenges to Raw Materials Supply

by Ana Rosa Castaño, Adalgisa Scotti, Vanesa Analia Silvani, Stefano Ubaldini, Francesca Trapasso, Emanuela Tempesta, Rita Rosa Plá, Margherita Giuffré, Natalia Andrea Juarez and Daniela Guglietta

Minerals 2023, 13(6), 765; https://doi.org/10.3390/min13060765 - 31 May 2023

Cited by 1 | Viewed by 1066

Abstract

In recent times, the development of innovative processes permits the application of a circular economy approach to the management and exploitation of mining waste with respect to human health and environment, such that society is changing its fundamentally negative perception of the mining [...] Read more.

In recent times, the development of innovative processes permits the application of a circular economy approach to the management and exploitation of mining waste with respect to human health and environment, such that society is changing its fundamentally negative perception of the mining sector. This study presents the opportunities and challenges of supplying raw materials from waste using a remote sensing technique, mycorrhizal-assisted phytoremediation, and hydrometallurgical techniques to transform mining waste from a problem to a resource. Soil/mine wastes from the Sierra Pintada mine (Mendoza, Argentina) were mineralogically and chemically analyzed, and then, a mapping of the mining waste was carried out by Sentinel-2A images to identify areas with similar characteristics. The bioaccumulation of HMs by autochthonous shrubs was also determined to select accumulator plant species, and to evaluate their potential for phytoremediation of mine soils at different technological scales, when they were inoculated with arbuscular mycorrhizal fungi originated from a mining-impacted area. RMs were recovered from plant biomass by scaling in bioreactors, the depuration module, and hydrometallurgical techniques. The encouraging results highlight that this multidisciplinary approach can be applied to meet the increasing demand for RMs supply and, at the same time, to protect the environment and public health. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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11 pages, 5134 KiB

Open AccessArticle

Thermodynamic Analysis of Mineral Phase Composition of Steel Slag System

by Shuai Hao, Guoping Luo, Yuanyuan Lu, Shengli An, Yifan Chai and Wei Song

Minerals 2023, 13(5), 643; https://doi.org/10.3390/min13050643 - 06 May 2023

Viewed by 990

Abstract

In order to transform the crystalline form of Ca₂SiO4 (C₂S) in phosphorus-containing slag from monoclinic β-polycrystalline to square γ-polycrystalline, a volume expansion of about 11% was generated, which caused the phosphorus-containing slag to undergo self-powdering. The CaO-SiO₂-Al [...] Read more.

In order to transform the crystalline form of Ca₂SiO4 (C₂S) in phosphorus-containing slag from monoclinic β-polycrystalline to square γ-polycrystalline, a volume expansion of about 11% was generated, which caused the phosphorus-containing slag to undergo self-powdering. The CaO-SiO₂-Al₂O₃-MgO-MnO-P₂O₅-FeO slag system was analyzed using FactSage7.1 thermodynamic software, and the effects of different P₂O₅, FeO and basicity on the mineral phase composition of slag system were analyzed in the range of 1300~1700 °C. It was shown that P₂O₅, FeO and basicity all have an effect on the composition of the mineral phases. When the mass fraction of P₂O₅ in the slag was lower than 0.25%, it had less effect on the transformation of C₂S crystalline structure. When the P₂O₅ content was higher than 0.25%, it was favorable to the generation of low-melting-point substances, but the P₂O₅ in the slag reacted with C₂S in the silicate phase, making P⁵⁺ solidly soluble in C₂S, inhibiting the transformation of β-C₂S to γ-C₂S and hindering the self-powdering of the slag. The FeO content in the slag system ranged from 20% to 28%, and as the FeO content increased, the C₂S content in the silicate phase decreased from 33.3% to 25.9%, while the temperature at which the silicate was completely dissolved into the liquid phase decreased from 1600 °C to 1500 °C and the complete melting temperature of the slag decreased. The low FeO content facilitates the self-powdering of slag. In the high-phosphorus slag, at temperatures below 1450 °C, with the increase of basicity, the proportion of C₂S in the silicate phase first increased and then decreased. With basicity at 1.8; the highest content of silicate phase, accounting for 33.7%; and the temperature exceeding 1450 °C, the silicate phase dissolved into the liquid phase, which is conducive to the removal of phosphorus from the slag, achieving the self-powdering of high-phosphorus slag. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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15 pages, 4474 KiB

Open AccessArticle

Viability of Morisca Powder Tailings for Ceramic Applications

by Antônio Alves de Carvalho Jr., Kelson de Sousa Leite and José Milton Elias de Matos

Minerals 2023, 13(4), 459; https://doi.org/10.3390/min13040459 - 24 Mar 2023

Cited by 1 | Viewed by 971

Abstract

In Juazeiro de Piauí and Castelo do Piauí, two cities in northeast Brazil, mined morisca rock is widely used in civil construction for external coating applications. Aiming at a sustainable practice for its extraction, which includes the economical use of the tailings from [...] Read more.

In Juazeiro de Piauí and Castelo do Piauí, two cities in northeast Brazil, mined morisca rock is widely used in civil construction for external coating applications. Aiming at a sustainable practice for its extraction, which includes the economical use of the tailings from its mining, this work presents a solution for the use of discarded materials from processing morisca from Piauí. In this context, an analysis of the results of using morisca as a substitute for clay materials for applications in red ceramics are presented. For the analyses, XRF, XRD, microgranulometry, limits of consistency, TG, DTG, and a set of technological tests inherent to ceramic materials were used. It was concluded that morisca powder is viable as a clay substitute for red ceramic applications. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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14 pages, 8710 KiB

Open AccessArticle

Features of the Physical-Mechanical Properties and Chemical Composition of Chert Gravels

by Mark Tzibulsky and Vladimir Frid

Minerals 2023, 13(4), 455; https://doi.org/10.3390/min13040455 - 23 Mar 2023

Viewed by 1344

Abstract

The chert gravels are a by-product of sand mining in the south of Israel; the reserves amount to tens of millions of tons and continue to grow. The attempts of their comminution for the production of aggregates by conventional mechanical methods have not [...] Read more.

The chert gravels are a by-product of sand mining in the south of Israel; the reserves amount to tens of millions of tons and continue to grow. The attempts of their comminution for the production of aggregates by conventional mechanical methods have not yet been successful due to the high abrasiveness, as well as the flaky form of their fracturing. This study was motivated by the need to find an alternative method to rock comminution that would ensure aggregate production in line with the requirements of the asphalt and concrete industry. This article deals with the first inevitable stage on the way to this goal, which consists of an extensive laboratory study of the physical and mechanical properties of the chert gravels, as well as the features of their chemical composition. The results show that the chert rock, consisting of quartz micro grains, contains calcium, sulfur, phosphorus, and barium impurities. The rock is characterized by extremely low porosity and water absorption (less than 1%) and high values of tensile strength (10.8 ± 3.3) and electrical resistivity (23.0 ± 11.9 kΩm). The cubic uniaxial compression strength of the rock is relatively not high (37.3 ± 10.4 MPa), which contradicts the assessment made based on the Schmidt hammer and Point Load studies (158 ± 30.4 MPa and 321 ± 118.5 MPa, respectively). Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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18 pages, 5292 KiB

Open AccessArticle

Utilization of Sugar Mill Waste Ash as Pozzolanic Material in Structural Mortar

by Nazmus Sakib, Rashidul Hasan, Azrul A. Mutalib, Maslina Jamil, Sudharshan N. Raman and A. B. M. A. Kaish

Minerals 2023, 13(3), 324; https://doi.org/10.3390/min13030324 - 24 Feb 2023

Cited by 2 | Viewed by 2231

Abstract

Bagasse is produced as a waste in the sugar production process, which is used as fuel to stoke boilers in the sugar mills. The concluding product of this burning is residual sugarcane bagasse ash (BA), which is normally dumped or used as low-quality [...] Read more.

Bagasse is produced as a waste in the sugar production process, which is used as fuel to stoke boilers in the sugar mills. The concluding product of this burning is residual sugarcane bagasse ash (BA), which is normally dumped or used as low-quality fertilizer. The ash for this study was collected from a reputed sugar mill located in the northern region of Bangladesh. Type I Portland cement (PC) was partially replaced with that finely ground bagasse ash without any pretreatment. The ground BA was used as a replacement for Portland cement at 5, 10, 15, 20, 25 and 30% of BA, respectively, in structural mortar. In addition, chemical characterization, specific gravity, X-ray diffraction (XRD), scanning electron microscopy (SEM), setting time, a strength activity index, compressive strength, water absorption, density and durability in a chloride environment of mortar were determined. The strength activity index result indicates that the used BA has the pozzolanic properties to be used as a partial cement replacement. The results showed that, at the age of 56 days, the mortar samples containing 5–15% ground bagasse ash had higher compressive strengths than the control mixture (mortar without ground bagasse ash). Mortar containing 15% ground bagasse ash had the highest mechanical and durability properties. Therefore, the substitution of 15% BA is acceptable for producing good quality structural mortar in the civil engineering construction field except in chloride environments. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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11 pages, 6009 KiB

Open AccessArticle

Effect of High Temperature Reconstruction and Modification on Phase Composition and Structure of Steel Slag

by Shuai Hao, Guoping Luo, Yuanyuan Lu, Shengli An, Yifan Chai and Wei Song

Minerals 2023, 13(1), 67; https://doi.org/10.3390/min13010067 - 30 Dec 2022

Cited by 3 | Viewed by 1330

Abstract

This study investigates the pattern of influence of blast furnace slag tempering on the composition and structure of steel slag. The chemical composition, equilibrium phase composition, microscopic morphological characteristics and elemental composition of microscopic regions of steel slag and blast furnace slag modified [...] Read more.

This study investigates the pattern of influence of blast furnace slag tempering on the composition and structure of steel slag. The chemical composition, equilibrium phase composition, microscopic morphological characteristics and elemental composition of microscopic regions of steel slag and blast furnace slag modified by high temperature reconstruction were analyzed using X-ray diffractometer (XRD), FactSage7.1 thermodynamic analysis software, mineral phase microscopy and field emission scanning electron microscopy. The results show that blast furnace slag blending can promote the generation of a low melting point phase in the slag, as well as reducing its melting temperature and improving its high temperature kinetic conditions. On the one hand, the incorporation of blast furnace slag was found to promote the generation of C₂S in the steel slag and improve its gelling activity. Notably, at 1400 °C, the C₂S content (mass fraction) of steel slag modified with 15% high temperature reconstruction reached 39.04%, while that of unmodified steel slag at this temperature was only 16.92%, i.e., only 1/4 of the C₂S content in the modified slag. On the other hand, the incorporation of blast furnace slag inhibited the generation of a-C₂S-C₃P and calcium ferrate minerals, refined the grains of calcium–aluminum yellow feldspar, reduced the alkalinity and promoted the generation of silicate phases with high hydration activity in steel slag. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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Review

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30 pages, 4462 KiB

Open AccessReview

Challenges, Regulations, and Case Studies on Sustainable Management of Industrial Waste

by Rajiv Ranjan Srivastava, Dilip Kumar Rajak, Sadia Ilyas, Hyunjung Kim and Pankaj Pathak

Minerals 2023, 13(1), 51; https://doi.org/10.3390/min13010051 - 28 Dec 2022

Cited by 7 | Viewed by 4331

Abstract

Incessant generation and mismanagement of industrial waste, resource scarcity, and environmental degradation have created non-sustainability in human life. Though industrial wastes are hazardous or non-hazardous in nature based on their source, open dumping disposal is commonly done for both types of waste. The [...] Read more.

Incessant generation and mismanagement of industrial waste, resource scarcity, and environmental degradation have created non-sustainability in human life. Though industrial wastes are hazardous or non-hazardous in nature based on their source, open dumping disposal is commonly done for both types of waste. The adversity associated with waste enhances the environmental and health impacts. However, this waste has the potential to recycle and minimize resource scarcity. The circular economy works on the concept of reuse, recycling, and recovery to convert waste into a resource. Thus, industrial waste can benefit the environment and economic growth to build industrial ecology. However, the opportunities and challenges associated with industrial ecology for the reuse and recycling of waste have to be identified and preserved. Therefore, this study has identified challenges associated with waste, analyzed their impact, and industrial regulations, prioritized their criticality, and developed solution strategies to alleviate them. Two case studies on industrial byproducts, i.e., fly ash and red mud, based on different income groups are discussed in this study. It highlights the circular economy has minimized waste generation and enhanced the recovery of secondary resource materials. In addition, this study supports achieving the sustainable development goals (SDGs) 11 and 12 to build a sustainable industrial ecosystem. Full article

(This article belongs to the Special Issue Management, Recycling and Reuse of Industrial Waste)

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