Recovery Of Valuable Minerals Research Articles

Virtual reassembling of 3D fragments for the data-driven analysis of fracture mechanisms in multi-component materials

This paper introduces a novel method for characterizing fracture mechanisms in multi-component materials using 3D image data gained by X-ray computed tomography (CT) measurements. In mineral liberation, the understanding of these mechanisms is crucial, particularly whether fractures occur along the boundaries of mineral phases (intergranular fracture) and/or within mineral phases (transgranular fracture). Conventional techniques for analyzing fracture mechanisms are focused on globally comparing the surface exposure of mineral phases extracted from image measurements before and after fracture. Instead, we present a virtual reassembling algorithm based on image registration techniques, which is applied to 3D data of multi-component materials before and after fracture in order to determine and characterize the individual fracture surfaces. This enables us to conduct a local quantitative analysis of fracture mechanisms by voxelwise comparing adjacent regions at fracture surfaces. A quantitative analysis of fracture mechanisms is especially important in the context of recycling processes. As primary deposits are decreasing worldwide and the focus is shifting on reducing wast, the interest in secondary raw materials has increased. However, lower-concentrated, but valuable materials are often overlooked in recycling routes designed for higher-concentration materials and dissipate. Therefore, efforts are being made to enrich valuable elements, such as lithium, as engineered artificial minerals through pyrometallurgical processes. The subsequent liberation through comminution processes, such as crushing, is essential for the recovery of valuable minerals. A better understanding of crushing processes, especially fracture mechanisms in slags, is crucial for the success of recycling. The reassembling algorithm presented in this paper is evaluated through a simulation study, followed by an application to a naturally occurring ore and a slag resulting from a recycling process.

Frothers in flotation: A review of performance and function in the context of chemical classification

The significance of frothers in the context of mineral flotation is widely recognized, particularly in relation to their impact on bubble size and dispersion, coalescence inhibition, as well as the structure and stability of the froth. All these parameters hold substantial importance in determining the feasibility of the process including the overall recovery of valuable minerals and concentrate grade in flotation process. This review aims to offer a comprehensive overview of the importance of frothers in the flotation process focusing on their performance and function in the context of their chemical classification. The characterisation of flotation frothers is discussed, focusing on the most often used parameters including molecular weight, hydrophilic-lipophilic balance (HLB), dynamic frothability, and interfacial tension measurement. Additionally, the importance of advanced characterisation techniques such as single rising bubble experiments, high-speed video microscopy and infrared reflection absorption spectroscopy (IRRAS) is highlighted. Finally, the application of biodegradable and environmentally friendly biosurfactants such as rhamnolipids as “green frothers” in enhancing flotation rates is outlined.

Simulating the Impact of Ore and Water Quality on Flotation Recovery during the Life of a Mine

Blending of different ore types in the concentrator feed contributes significantly to maintaining a high recovery of valuable minerals with required grades in the concentrate. It is feasible to develop an ore-blending scheme over the life of a mine already in the design phase of the plant. In addition to ore characteristics, water quality is known to impact mineral recovery. A blending plan could also be developed for the different water streams of a future concentrator. This paper describes a novel modeling and simulation approach to predict metallurgical response combining ore types and water quality. The model is based on kinetic laboratory flotation test data, and it was tested on a case study. As a result, rougher flotation grade-recovery curves dependent on ore types and water quality are presented over the predicted life of the mine. The simulation results can be exploited in project design to maximize the recovery of valuable minerals and to ensure environmentally sound and profitable mining operations. Overall, the developed modeling tool can be applied widely for minerals processed by using froth flotation and water types available for kinetic laboratory flotation tests.

Improving Nickel Recovery in Froth Flotation by Purifying Concentrators Process Water Using Dissolved Air Flotation

The pressure for saving water by closing the water loops in mineral processing is increasing continuously. The drivers for higher recirculating rates include water scarcity in dry areas, environmental legislation that is becoming stricter in most countries, limitations set for wet tailings management and the increased demands for social licenses to operate. At the same time, to make mineral processing sustainable, the recovery of valuable minerals should be maximized. This leads for a need to close the process water circulation. To see the effect of closed water circulation on metallurgical performance, flotation tests were carried out with nickel concentrate thickener overflow water before and after the process of water purification by dissolved air flotation (DAF). Both total nickel recovery and concentrate grade in laboratory scale flotation tests to the Ni rougher-scavenger concentrate increased after DAF treatment. Chemical and mineralogical characterizations revealed that after DAF treatment, the process water contained fewer metal hydroxides and less fine-grained silicate mineral particles, which is most likely the reason for the improvement in the nickel flotation performance. Based on the feasibility study, improved nickel recovery by DAF treatment of process water can bring economic benefits at a concentrator plant.

Effective treatment of real acid mine drainage using MgO-metakaolinite nanocomposite

In this study, synergistic effects of mechanochemically synthesized metakaolinite-Ca-rich-MgO nanocomposite for effective treatment of real acid mine drainage (AMD) was meticulously reported. The obtained results were underpinned using the state-of-the-art analytical techniques and instruments, such as FTIR, HR-FIB/SEM, EDS, XRF, and XRD. The pH REdox EQuilibrium (in C language) was employed to complement experimental results. Optimum conditions were observed to be 45–60 min of mixing time, ≥10 g L−1 of feedstock dosage, i.e. nanocomposite, and ambient temperature and pH. The metal content (Fe, Mn, Cr, Cu, Ni, Pb, Al, and Zn) embedded in real AMD matrices was practically depleted (>99 % removal) and sulphate greatly reduced (≥50 %). PHREEQC predicted metals to exist as mono-, di-, and-tri-valents including variety of chemical complexes, and they precipitated as metals hydroxides, (oxy)-hydroxides, carbonates, and (oxy)-hydro-sulphates. This synergistic treatment approach holds great promise for the sustainable management of real AMD effluents from coal mining activities and can provide a simple and effective solution for its management. Thenceforth, softening and filtration technologies will need to be coupled to this process to further enhance the reclamation of drinking and to explore possible recovery of valuable minerals from the generated sludge.

The Electrochemical Response of Chalcopyrite and Galena to Degrading Water Quality

Water is used as a liquid medium as well as a means of transportation during mining operations. Flotation, in particular, is a water intensive process where water makes up about 80–85% of the pulp phase. Process water contains organic and inorganic species which accumulate as they are recycled. To avoid the treatment costs of removing these contaminants, many mining operations allow the quality of their water to degrade over time. When this water is introduced into flotation circuits, the pulp chemistry is altered. Ionic species that accumulate in recycled process water have been shown by previous studies to be especially deleterious to flotation performance. Such ions include Ca2+, Cu2+, Mg2+, Pb2+, SO42− and S2O32−, amongst others. The flotation sub-process of collector adsorption which is responsible for inducing hydrophobicity on valuable mineral surfaces may be influenced by water chemistry. Accumulating ionic species have been shown to hinder collector adsorption which may reduce recovery of valuable minerals to the concentrate. Consequently, degrading water quality may threaten the economic viability of mining operations that make use of closed water circuits. Electrochemical techniques such as mineral rest potentials can be used to monitor the impact of changing water quality on collector–mineral interactions. Microflotation was used to determine whether mineral floatability was affected by changing water quality. This study therefore aimed to investigate whether electrochemical techniques such as rest potential measurements can be used to predict flotation performance under changing water quality. No definable relationship was found between the rest potential differences and the microflotation initial recoveries, however, rest potential measurements did identify the negative impact that thiosulphate ions may have on flotation processes.

Mining minerals and critical raw materials from bittern: Understanding metal ions fate in saltwork ponds

Seawater represents a potential resource for raw materials extraction. Although NaCl is the most representative mineral extracted other valuable compounds such as Mg, Li, Sr, Rb and B and elements at trace level (Cs, Co, In, Sc, Ga and Ge) are also contained in this “liquid mine”. Most of them are considered as Critical Raw Materials by the European Union. Solar saltworks, providing concentration factors of up-to 20 to 40, offer a perfect platform for the development of minerals and metal recovery schemes taking benefit of the concentration and purification achieved along the evaporation saltwork ponds.However, the geochemistry of these elements in this environment has not been yet thoroughly evaluated. Their knowledge could enable the deployment of technologies capable to achieve the recovery of valuable minerals. The high ionic strengths expected (0.5–7 mol/kg) and the chemical complexity of the solutions imply that only numerical geochemical codes, as PHREEQC, and the use of Pitzer model to estimate the activity coefficients of the different species in solution can be adopted to provide valuable description of the systems.In the present work, for the first time, PHREEQC Pitzer code database was extended to include the target minor and trace elements using Trapani saltworks (Sicily, Italy) as a case study system. The model was able to predict: i) the purity in halite and the major impurities contained, mainly Ca, Mg and sulphate species; ii) the fate of minor components as B, Sr, Cs, Co, Ge and Ga along the evaporation ponds. The results obtained pose a fundamental step in critical raw materials mining from seawater brine, for process intensification and combination with desalination.

Recovery of Valuable Minerals from Sea Water by Membrane Separation and Adsorption Process: A Review

Recovery of Valuable Minerals from Sea Water by Membrane Separation and Adsorption Process: A Review

Development of Nitrogen Recycling Strategies for Bioregenerative Life Support Systems in Space.

To enable long-distance space travel, the development of a highly efficient and robust system to recover nutrients from waste streams is imperative. The inability of the current physicochemical-based environmental control and life support system (ECLSS) on the ISS to produce food in situ and to recover water and oxygen at high enough efficiencies results in the need for frequent resupply missions from Earth. Therefore, alternative strategies like biologically-based technologies called bioregenerative life support systems (BLSSs) are in development. These systems aim to combine biological and physicochemical processes, which enable in situ water, oxygen, and food production (through the highly efficient recovery of minerals from waste streams). Hence, minimalizing the need for external consumables. One of the BLSS initiatives is the European Space Agency’s (ESA) Micro-Ecological Life Support System Alternative (MELiSSA). It has been designed as a five-compartment bioengineered system able to produce fresh food and oxygen and to recycle water. As such, it could sustain the needs of a human crew for long-term space exploration missions. A prerequisite for the self-sufficient nature of MELiSSA is the highly efficient recovery of valuable minerals from waste streams. The produced nutrients can be used as a fertilizer for food production. In this review, we discuss the need to shift from the ECLSS to a BLSS, provide a summary of past and current BLSS programs and their unique approaches to nitrogen recovery and processing of urine waste streams. In addition, compartment III of the MELiSSA loop, which is responsible for nitrogen recovery, is reviewed in-depth. Finally, past, current, and future related ground and space demonstration and the space-related challenges for this technology are considered.

Challenges and opportunities for development of the Vietnam mineral processing in the XXI century

Mineral mining and processing Industry of Vietnam is facing a number of huge challenges at present, but there are also great opportunities for its growth in the future. Mineral processing plants need to make breakthrough improvements in the process designing, technology and equipment utilisation in order to meet requirements of the new era. These challenges force our miners and mineral processing operators to constantly make efforts in researches and to bring best solutions to improve plant operations to ensure the requirements of safety, market demands, product quality, sustainable development and environmental friendliness. Specifically, the issues that need to be addressed urgently are capacity and quality of the workforce, tailings treatment, fine particle processing, ores of low washability, recovery rate increase and maximisation of recoverable valuable minerals, environmental issues and workplace safety monitoring and control, maximasation of production efficiency and reduction of operating costs. This report presents the current key challenges of the mining and mineral processing industry in order to help professionals and policy makers in the field of mineral mining and processing to bring rational directions for action initiate appropriate studies and improve management methods; to help mineral processing plants in improving the production efficiency and recovery of valuable minerals; to reduce operating costs and to become environmentally friendly and to develop sustainably.

Bubble size distributions in gas–liquid–solid systems and their influence on flotation separation in a bubble column

Measurements of bubble size distributions are very important in flotation which is widely used in different chemical industries such as the recovery of valuable minerals, wastewater treatment, deinking of waste paper, and oil recovery from tar sands. Although numerous authors determined bubble size distributions (BSD-s) in gas–liquid systems, BSD-s have been rarely determined in gas–liquid–solid systems. Moreover, the influence of BSD-s on flotation has not been quantified under a wide range of experimental conditions. Thus, this paper is focused on measurements of bubble size distributions by changing surfactant dosage, solid percentage, air velocity and particle size as well as establishing the relationships between bubble size distribution properties and flotation performances. It was found that the experimental bubble size distributions are successfully fitted by using the log-normal distribution model in which the two model parameters (μ and σ) are used. The results showed that the most important factors affecting the Sauter mean diameter (d32), the model parameters and the flotation recoveries are the surfactant dosage and the solid percentage. The increase in the surfactant dosage decreased d32 probably due to the decrease in liquid surface tension. The increase in solid percentage resulted in an increase in d32 perhaps due to the increase in the pulp viscosity at high solid percentage. The lower the d32, the lower the flotation recovery. The results show that d32 and the model parameters represent the true BSD-s. However, a thorough understanding of bubble size distributions is needed to better understand flotation performances.

Simulating the Effect of Water Recirculation on Flotation through Ion-Spiking: Effect of Ca2+ and Mg2+

Froth flotation is a multifaceted complex process which is water intensive. The use of recycled water as an alternative source of water to meet water demands of the process may introduce deleterious inorganic ions that affect the mineral surface, pulp chemistry, and reagent action, hence the need to establish whether threshold ion concentrations exist beyond which flotation performance will be adversely affected. This is of paramount importance in informing appropriate recycle streams and allowing simple, cost-effective water treatment methods to be applied. Here we report that increasing ionic strengths of synthetic plant water (SPW); 3, 5, and 10 SPW respectively, resulted in an increase in water recovery in the order 0.073 mol·dm−3 (3 SPW) < 0.121 mol·dm−3 (5 SPW) < 0.242 mol·dm−3 (10 SPW), indicating an increase in froth stability as higher water recoveries are linked to increased froth stabilities. This behavior is linked to the action of inorganic electrolytes on bubble coalescence which is reported in literature. There was, however, no significant effect on the valuable mineral recovery. Spiking 3 SPW to 400 mg/L Ca2+ resulted in higher copper and nickel grades compared to 3 SPW, 5 SPW, and 10 SPW and was deemed to be the Ca2+ ion threshold concentration for this study since 3 SPW spiked with further Ca2+ to a concentration of 800 mg/L resulted in a decrease in the concentrate grade. The spiking of 3 SPW with Mg2+ resulted in higher copper and nickel grades compared to all other synthetic plant water conditions tested in this study.

The Process of Microbiological Remediation of the Polluted Słoneczko Reservoir in Poland: For Reduction of Water Pollution and Nutrients Management

The article discusses the impact of nutrients from sewage on the state of the sewage receiver. Bioremediation was carried out through the use of effective microorganisms. The potential recovery of valuable mineral and organic substances in the form of fertilizers was also examined. The Słoneczko Reservoir is a bathing area and serves many people in the summertime as a place of water recreation. Water quality deteriorated intensively from 2006 as a result of illegal wastewater discharge and the impact of fecal pollution from bathers. The high concentration of nutrients in the water was the cause of the eutrophication process and blooms of cyanobacteria, which pose a threat to human health in the bathing area. The bathing area was also closed many times by sanitary services as a result of exceeding the number of Escherichia coli and Enterococcus faecalis in the water. At the bottom of the reservoir, there was a layer of sediments with a thickness of 30–70 cm. Thus, the processes of anaerobic decomposition generated odor, causing nuisance in the reservoir area. Water transparency varied from 30 to 50 cm, due to the accumulation of suspensions and biomass of planktonic algae. The reservoir was subjected to microbiological bioremediation in 2017 and 2018 to polluted water treatment and to reduce the organic content of bottom sediments. Already after the first application of biopreparations putrefactive odors and the eutrophication process disappeared at the end of the 2017 summer season. Bioremediation reduced the value of E. coli and E. feacalis to the acceptable level. After the second application in 2018, the organic fraction of the bottom sediments was reduced to a very low level and the water transparency reached the bottom (maximum depth was 2.2 m) throughout the entire bathing area. The effect of the water remediation was maintained until 2019, and the surface water quality remained at a very good level. An important aspect in this case is also the exploitation of bottom sediments, because they are rich in nutrients and organic matter, and therefore it may have some potential as a fertilizer. The recovery of nutrients can be used in plant or pot production. However, they contain compounds that degrade quickly, causing unpleasant odors and threatening the environment. Thus, they should be managed and handled in an environmentally friendly and sustainable way.

Using Partial Desalination Treatment To Improve the Recovery of Copper and Molybdenum Minerals in the Chilean Mining Industry

Limited water resources and greenhouse gas emissions from fossil fuels used in electricity production are problems experienced in Chile. To address water shortages, many copper mining companies have started to use seawater or desalinated water in their operations. However, seawater exerts a negative impact on the mineral processing operation. It reduces the recovery of copper and molybdenum minerals in the flotation of copper–molybdenum sulfide ores due to the presence of calcium and magnesium ions. This study aims to propose a partial desalination treatment for calcium and magnesium species removal to improve the recovery of valuable minerals in the flotation of copper–molybdenum sulfide ores. The proposed method uses carbon dioxide gas and sodium hydroxide to promote the removal of calcium and magnesium ions from seawater. As a result, the partial desalination treatment can remove 60.5% of calcium and 98.3% of magnesium species. In addition, it helped in reaching a high recovery of molybdenum (81.1%) an...

Effect of mineral particle size on froth stability

ABSTRACT Mineral particles offer an added stability to three phase froths, in addition to the stability imparted by frothers. The ability of particles to influence froth stability is particle size dependent. Knowledge of the quantitative effect of particle size on froth stability is essential for froth flotation model development and prediction. This study investigated the extent to which discrete particle size fractions, as well as mixtures of particle size classes, affect the stability of three phase froths in a synthetic pyrite-quartz ore. A novel bench-scale continuous column flotation cell was used to assess froth stability and metallurgical performance. Results obtained show that froth stability decreases as a function of increasing feed particle size. When particle size is transformed to surface area, a linear relationship between froth stability and particle specific surface area is obtained. The effect on flotation performance is reflected by an increase in valuable mineral recovery as froth stability increases.

Nanobubble effects on hydrodynamic interactions between particles and bubbles

Particle-bubble interactions play a vital role in froth flotation that is widely used for the recovery of valuable minerals from gangue minerals. In this study the effects of nanobubbles on particle-bubble interactions were visualized using a specially designed apparatus to show the trajectory of solid particles of different degrees of hydrophobicity moving around a regular sized flotation bubble. It has been shown that particle hydrophobicity and the nanobubbles generated on particle surface enhance the particle-bubble interaction process by affecting the balance between the hydrodynamic and surface chemistry forces that control the trajectory of a particle moving around a bubble surface. Increased particle surface hydrophobicity in terms of contact angle from 50o to 85o and 110o enhanced the particle-bubble interaction by reducing the induction time from 75 ms to 52 ms and 48 ms, respectively. In the presence of nanobubbles on particle surface, the thin film between the particle and the bubble ruptures up to 50% faster. It has also been observed that nanobubbles are capable of producing fine particle aggregates that facilitate the particle-bubble interaction process.

Effects of nanobubble and hydrodynamic parameters on coarse quartz flotation

Quartz, the second most abundant mineral in the earth’s crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles (NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of −425 + 106 μm quartz by up to 21%. For the 7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number (Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.

Effect of using different grinding media on the flotation of a base metal sulphide ore

In the present investigation flotation was used as a diagnostic to understand the effects of changes to the media during the grinding stage. A Base Metal Sulphide (BMS) ore was ground under media of different shapes and compositions to determine the effect of different rod/ball material on the flotation performance of the ore. The observations from flotation for different media are discussed in terms of water recovery, solid recovery and valuable mineral recovery. The chemical parameters; pH, redox potential (Eh) and dissolved oxygen (DO) levels were measured. For a given grind (D80 = 75 μm), media shape had no effect on flotation performance of a BMS ore. Different grinding media had significant effects on slurry chemical properties and flotation performance. Mild steel rods (RMMS) produced the highest solids recovery, nickel and pyrrhotite (Po) recovery, with the highest ethylenediaminetetraacetic acid (EDTA) extractable iron and the lowest DO level. Chrome steel balls and stainless steel rods produced the lowest metal recovery, EDTA extractable iron and the highest DO level. Ferric ions were seen to depress talc.

Effect of different grinding media composition on the flotation of a PGM ore

In the present study, the effect of using different grinding media, viz, ceramic (CE), forged steel (FS), 15% Cr steel (CS), stainless steel (SS) and a mixture of stainless steel and 15% Cr steel balls (50:50) (SS + CS) were investigated using a Platinum Group Metal (PGM) ore, UG2. Test work was conducted using a laboratory scale horizontal tumbling mill and a batch flotation cell. Power draw to achieve a specific P80 was determined for each media type. The different flotation behaviour obtained from different media is discussed in terms of particle size distribution, water recovery, solid recovery and valuable mineral recovery. pH, Redox potential (Eh) and dissolved oxygen (DO) level were also measured. Grinding products of five different media produced the same solids and water recovery, but the grades and recoveries of PGM and chromite were different. Grinding products of ceramic media had the best flotation performance, which produced the highest PGM recovery and the lowest Cr2O3 recovery. Meanwhile grinding products of stainless steel balls (SS) produced the lowest PGM recovery and highest Cr2O3 grade and recovery in the concentrates. The paper proposes possible reasons to explain these observations.

A conservation law with multiply discontinuous flux modelling a flotation column

Flotation is a unit operation extensively used in the recovery of valuable minerals in mineral processing and related applications. Essential insight to the hydrodynamics of a flotation column can be obtained by studying just two phases: gas and fluid. To this end, the approach based on the drift-flux theory, proposed in similar form by several authors, is reformulated as a one-dimensional non-linear conservation law with a multiply discontinuous flux. The unknown is the gas volume fraction as a function of height and time, and the flux function depends discontinuously on spatial position due to several feed inlets. The resulting model is similar, but not equivalent, to previously studied clarifier-thickener models for solid-liquid separation and therefore adds a new real-world application to the field of conservation laws with discontinuous flux. Steady-state solutions are studied in detail, including their construction by applying an appropriate entropy condition across each flux discontinuity. This analysis leads to operating charts and tables collecting all possible steady states along with some necessary conditions for their feasibility in each case. Numerical experiments show that the transient model recovers the steady states, depending on the feed rates of the different inlets.