Precipitation Of Co Research Articles

High-Selective Separation Recovery of Ni, Co, and Mn from the Spent LIBs Via Acid Dissolution and Multistage Oxidation Precipitation.

For recovering Ni, Co, and Mn from lithium-ion batteries, traditional chemical precipitation methods demonstrate low selectivity and significantly contribute to environmental pollution. This study proposes a separation recovery technique for transition metals, specifically Ni, Co, and Mn, from spent LIBs, involving "acid dissolution" and "multistage oxidation precipitation". More than 98 % of transition metals can be extracted from spent LIBs using a low acid concentration (0.5 M) without reducing agents. The feasibility of separating different metals via multistage oxidation precipitation, based on their different electrode potentials for oxidizing Me2+ (Me=Mn/Co/Ni), was confirmed. The combination of oxidizing agent S2O8 2- and the precipitant OH- was universally applied to the fractional precipitation of Mn, Co, and Ni respectively. About 99 % of Mn, 97.06 % Co, and 96.62 % Ni could be precipitated sequentially by changing the concentrations of S2O8 2- and the pH value of solution. XRD, XPS, XRF, ICP-MS and other methods were employed to elucidate the mechanism behind the multistage oxidation precipitation of target metal compounds, exploiting the differential electrode potentials for oxidizing Me2+ ions. This technique surpasses traditional solvent extraction in cost-effectiveness and selectivity, showing promise for large-scale industrial applications in recovering Mn, Co, and Ni.

A novel closed-loop biotechnology for recovery of cobalt from a lithium-ion battery active cathode material.

In recent years, the demand for lithium-ion batteries (LIBs) has been increasing rapidly. Conventional recycling strategies (based on pyro- and hydrometallurgy) are damaging for the environment and more sustainable methods need to be developed. Bioleaching is a promising environmentally friendly approach that uses microorganisms to solubilize metals. However, a bioleaching-based technology has not yet been applied to recover valuable metals from waste LIBs on an industrial scale. A series of experiments was performed to improve metal recovery rates from an active cathode material (LiCoO2; LCO). (i) Direct bioleaching of ≤0.5 % LCO with two prokaryotic acidophilic consortia achieved >80 % Co and 90 % Li extraction. Significantly lower metal recovery rates were obtained at 30 °C than at 45 °C. (ii) In contrast, during direct bioleaching of 3 % LCO with consortia adapted to elevated LCO levels, the 30 °C consortium performed significantly better than the 45 °C consortium, solubilizing 73 and 93 % of the Co and Li, respectively, during one-step bioleaching, and 83 and 99 % of the Co and Li, respectively, during a two-step process. (iii) The adapted 30°C consortium was used for indirect leaching in a low-waste closed-loop system (with 10 % LCO). The process involved generation of sulfuric acid in an acid-generating bioreactor (AGB), 2-3 week leaching of LCO with the biogenic acid (pH 0.9), selective precipitation of Co as hydroxide, and recirculation of the metal-free liquor back into the AGB. In total, 58.2 % Co and 100 % Li were solubilized in seven phases, and >99.9 % of the dissolved Co was recovered after each phase as a high-purity Co hydroxide. Additionally, Co nanoparticles were generated from the obtained Co-rich leachates, using Desulfovibrio alaskensis, and Co electrowinning was optimized as an alternative recovery technique, yielding high recovery rates (91.1 and 73.6% on carbon felt and roughened steel, respectively) from bioleachates that contained significantly lower Co concentrations than industrial hydrometallurgical liquors. The closed-loop system was highly dominated by the mixotrophic archaeon Ferroplasma and sulfur-oxidizing bacteria Acidithiobacillus caldus and Acidithiobacillus thiooxidans. The developed system achieved high metal recovery rates and provided high-purity solid products suitable for a battery supply chain, while minimizing waste production and the inhibitory effects of elevated concentrations of dissolved metals on the leaching prokaryotes. The system is suitable for scale-up applications and has the potential to be adapted to different battery chemistries.

Effects of multistage thermomechanical treatment on the microstructure and properties of Cu–Ni–Co–Si–Mg alloy strip by HCCM horizontal continuous casting

Multistage thermomechanical treatment experiments were conducted on Cu–Ni–Co–Si–Mg alloy strip prepared by the Heating Cooling Combined Mold (HCCM) horizontal continuous casting-cold rolling process. Effects of various heat treatments on the microstructure, mechanical properties, and electrical conductivity of the alloy were studied. The strengthening mechanisms and factors influencing the performance of each process has been analyzed. The tensile strength, yield strength, and electrical conductivity of Cu–Ni–Co–Si–Mg alloy can reach 894 MPa, 855 MPa, and 47.1 %IACS after a third-stage of thermomechanical treatment (TTMT). The cold rolling in first-stage of thermomechanical treatment (FTMT) not only caused work hardening of the alloy but also promoted the precipitation of solute atoms and the growth of second phase particles, limiting the increase in strength. Second-stage of thermomechanical treatment (STMT) effectively hindered the excessive growth of second phase particles in FTMT but shortened recrystallization process. The superior performance of Cu–Ni–Co–Si–Mg alloy after TTMT was attributed to dispersive precipitation of Ni, Co, and Si elements as (Ni, Co) 2Si phases in the copper matrix, strengthening the interaction between the precipitates and dislocations. A short process of HCCM horizontal continuous casting-cold rolling-thermomechanical treatment was developed to produce a high strength and highly electrically conductive Cu–Ni–Co–Si alloy strip used in lead frames.

RETRACTED: Engineering a high-performance W-doped Sr0.9Fe0.67Ti0.3Co0.03O3-δ hydrogen electrode for Solid Oxide Electrolysis Cells (SOECs)

Traditionally, Ni-based cermet fuel electrodes have been extensively utilized in Solid Oxide Electrolysis Cells (SOECs) for their excellent conductivity and catalytic properties. However, the development of alternative materials has gained attraction due to concerns over Ni's susceptibility to carbon deposition and long-term stability issues. To overcome this issue, we designed Sr0.9Fe0.67Ti0.30Co0.07O3-δ (SFTC) and W-doped SFTC (SFTCW) via the sol-gel method and thoroughly characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG-DSC), and electrochemical tests. The results reveal that the incorporation of W enhances the stability of the electrode material under both oxidizing and reducing conditions, with no impurity phases detected. Furthermore, W doping promotes the precipitation of Co–Fe alloy, preserves the original structure, and facilitates the creation of oxygen vacancies within the material. In a reducing atmosphere containing 40 % H2O, SFTCW demonstrates superior electrolysis performance at an electrolysis voltage of 1.8 V, exhibiting a remarkable improvement of approx. 35 % compared to the SFTC sample. During a 100 h long-term stability test, the current density of SFTCW increased from -240 mA cm–2 to -270 mA cm–2, attributed to the enhanced hydrogen oxidation activity and increased reactive sites resulting from W doping, thereby enhancing its long-term stability. This work provides a feasible scheme for the selection and construction of hydrogen electrodes for electrolytic water.

Investigating the strengthening and deformation behavior of B2-strengthened high entropy alloys with high Co and Al contents

A never-ending challenge for materials scientists is to design alloys with excellent strength-ductility combinations. Here, a systematic study on B2 precipitation and mechanical behaviors of a high Co and Al content high entropy alloy (HEA) annealed at 700–1000 °C was investigated. The alloy annealed at 700 °C (denoted as A700) exhibited a high yield strength of 1820 ± 22 MPa and an ultimate tensile strength of 1884 ± 21 MPa, which can be mainly attributed to the dislocation, ultra-fine grain and B2-strengthening. With the annealed temperature increasing to 900 °C (denoted as A900), the FCC matrix has been full-recrystallized, and the grain size of FCC matrix increases from 0.21 μm to 2.8 μm. The volume fraction of the B2 phase decreases slightly from 58% to 53%. As a result, the A900 alloy displays a yield strength of 1038 ± 17 MPa and tensile ductility of 28 ± 2.3%. The deformation and strengthening mechanisms are investigated by microstructural characterization and theoretical calculations. This work will provide a basis for the composition and structural design of B2-strengthened HEAs.

Assessing the impacts of climate variables on long-term air quality trends in Peninsular Malaysia

Climate change is thought to influence the composition of atmospheric air, but little is known about the direct relationship between these variables, especially in a hot tropical climate like that of Malaysia. This work summarizes and analyzes the climate state and air quality of Peninsular Malaysia based on selected ground-based observations of the temperature, precipitation, relative humidity, wind speed, wind direction and concentrations of PM10, O3, CO, NO2, and SO2 over the last 20 years (2000–2019). The relationship between the climate state and air quality is analyzed using the Pearson correlation and canonical correlation analysis (CCA) methods is employed to predict the degree of change in the future air quality under different warming scenarios. It is found that the Peninsular Malaysia mainly experienced strong precipitation in the central and mountainous regions, while air pollutants are primarily concentrated in densely populated areas. Throughout the period of study (interannual, monthly, and diurnal time series analyses), Peninsular Malaysia became warmer and drier, with a significant increase in temperature (+4.2 %), decrease in the relative humidity (−4.5 %), and greater fluctuation in precipitation amount. The pollution conditions have worsened; there has been an increase in the PM10 (+16.4 %), O3 (+39.5 %), and NO2 (+2.1 %) concentration over the last 20 years. However, the amount of SO2 (−53.6 %) and CO (−20.6 %) decreased significantly. The analysis of the monthly variation shows a strong bimodality of the PM10 and O3 concentrations that corresponds to the monsoon transition. Intensive diurnal fluctuations and correlations are observed for all the variables in this study. According to the CCA, the air quality factors are strongly correlated with meteorological factors; in particular, the CO, O3, and PM10 concentrations interact strongly with the air temperature. These findings show that the future air quality in Peninsular Malaysia has high possibility to deteriorate under warming condition.

Recovery of molybdenum from (Co – Mo / - Al2O3) spent catalyst

In the present research, hydro – desulfurization spent catalyst with an alumina base has been found to be as a source for molybdenum recovery. It was compose of 19 - 30 % of molybdenum as MoO3. Two methods were used for the recovery of molybdenum. First method was using H2S gas for precipitation of Co as CoS, and the precipitation of Mo has been done by HCl acid solution addition. The second method was the alkali leaching of spent catalyst and recovery of molybdenum using dilute NH4OH solution and then the precipitation of molybdenum as trioxide using HCl solution. The optimum conditions were predicated for the recovery of molybdenum, and different parameters were studied such as the alkali concentration and leaching time.

Prediction of reduction products in the preheating process

Under the current requirements of environmental protection, carbon peaking and carbon neutrality goals, the capacity of the new energy interconnection network is increasing day by day. The thermal power unit requires the ability of rapid load adjustment to meet the requirements of real-time power balance. However, when the unit is in a variable load condition, the denitrification system is inefficient or even inoperable. The NOx emission is large, which makes it difficult to meet environmental protection requirements. In this study, a new method for predicting reductive products in the preheating process is proposed, introducing the gasification mechanism into the pulverized coal preheating process. The effects of air coefficient on combustion temperature, velocity, O2, CO2, CO, CH4, and H2, volatile matter and NOx emission are investigated by numerical simulation. It is demonstrated that the gasification mechanism is applicable to predict the reduction products and NOx during preheating. Internal combustion burners can stabilize the precipitation of volatile matter, CH4, CO, and H2. The burner outlet temperature and flow rate decrease with decreasing air coefficient. The local maximum concentration of volatile matter and CH4 are 8.3 vol.% and 2.54 vol.%, respectively. The CO concentration increases with decreasing air coefficient under the effect of CO2 gasification reaction. When the air coefficient is 0.33, the NOx concentration at the burner outlet is 2.8 mg/Nm3 (at 6% O2).

Preliminary Study of LiCoPO4 cathode material synthesis for LiCoPO4/Graphite Cell

<p>Nowadays, the race towards a high-performance Li-ion batteries discovery for energy storage has become an interesting technological challenge. New or improved Li-ion battery cathodes have been developed relentlessly in this decade. LiCoPO<sub>4</sub> (LCP) is a cathode material that allow a battery to operate at high voltage which resulted a high energy density battery. The presence of strong P-O bond adds a thermal stability feature to LIB cells. In this study, a LiCoPO<sub>4</sub> material were prepared by precipitation of Co<sub>3</sub>(PO<sub>4</sub>)<sub>2</sub> (CP) followed by high temperature Li insertion. H­<sub>3</sub>PO<sub>4</sub> were used as the phosphate source. The crystallization or precipitation of CP can only be achieved under mild pH condition, which can be controlled using sodium hydroxide. XRD, SEM and FTIR analysis were used to characterize the final product. The as-obtained LCP were applied as cathode material while graphite was used as the counter anode. The cell can deliver a charge-discharge capacity at a voltage of 2.0-4.95 V. This preliminary can be a groundwork toward the commercialization of LCP based Li-ion batteries for high duty application.</p>

Synthesis of Carbon Nanoparticles with Cobalt-Rich Shell via Pyrolysis of Zn-ZIF@Co/Zn-ZIF: Relevance of Co(III) Precursors

To the best of our knowledge, this is the first report on the rapid one-pot synthesis of a unique core-shell-structured zeolitic imidazolate framework (ZIF) using Co(III) and Zn(II) precursors. The key to obtaining this unique structure is the use of a Co(III) precursor as the starting material. Transmission electron microscopy (TEM) reveals that Co was present within a 30-nm-thick shell layer of the ZIF material. Thermal decomposition of the ZIF material affords core-shell-structured carbon nanoparticles that have Co on the external surface of the carbon grain. We have previously demonstrated that this carbonaceous material obtained by thermal decomposition exhibited high performance as an adsorbent for nitric oxide, even in the presence of excess oxygen and water vapor, and therefore, it was a suitable material for NOx elimination at low temperatures. The growth mechanism of the synthesized ZIF particles and the differences between synthesized ZIF and conventional Co(II)-ZIF-67 are discussed. The reactivity of the Co(III) precursor is much lower than that of the Co(II) species, leading to slower precipitation of Co(III) than that of Zn(II), thus forming the core-shell structure.

Recycling the cathode materials of spent Li-ion batteries in a H-Shaped neutral water electrolysis cell

• A large pH gradient is generated in a neutral water electrolysis cell. • The pH gradient allows concurrent LiCoO 2 leaching and Co(OH) 2 precipitation. • The use of external acid and base is avoided. • The Co(OH) 2 and Li 2 CO 3 recovered were calcined to resynthesize new LiCoO 2 . • The treatment of LiMn 2 O 4 and NCM with this process was also investigated. The recycling of Li-ion batteries is becoming increasingly urgent due to the rapid accumulation of spent Li-ion batteries from aging portable electronics and electric vehicles. The lack of environmentally and economically feasible recycling technologies will not only cause material losses and environmental contamination, but also poses a serious limit for the penetration of more Li-ion batteries in electric vehicles and grid-scale energy storage applications. Here, we present a proof-of-concept demonstration of an innovative process for recycling cathode materials of Li-ion batteries in a neutral water electrolysis cell. During electrolysis, an electrochemical pH gradient was generated, which enables the leaching of waste LiCoO 2 at low pH in the anode chamber and the precipitation of solid Co(OH) 2 at high pH in the cathode chamber. The Co(OH) 2 precipitates can be readily filtered and separated from the electrolysis cell. In addition, the Li + is recovered in the form of Li 2 CO 3 . Unlike conventional hydrometallurgical processes and other aqueous electrochemical processes, this work harnesses the in-situ electrochemical pH gradient generated by neutral water electrolysis. This allows concurrent LiCoO 2 leaching and Co(OH) 2 precipitation at separate chambers and avoids the use of external acid and base, extractant or ion-selective polymer electrolyte membrane. This method is also extended to recycling waste LiMn 2 O 4 and LiNi 0.5 Co 0.2 Mn 0.3 O 2 . Therefore, this new process represents a green advance for recycling the waste cathode materials of the Li-ion batteries.

Physical Regularities for Cellular Precipitation of Co-, Cu-, and Pb-Based Supersaturated Solid Solutions

The decomposition of supersaturated solid solutions through the cellular mechanism is considered in terms of the physical regularities of this phenomenon. The general characteristics of this process are described. The mechanisms of nucleation and subsequent cell growth, as well as kinetic parameters of processes, are partially described. The influences of some external factors on the cellular precipitation process and its stages are characterized. Particularly, the effects of annealing temperature and a third element on the cellular precipitation process are studied.

An investigation into potential pathways for nickel and cobalt loss during impurity removal from synthetic nickel laterite pressure acid leach solutions via partial neutralisation

The primary pathways by which nickel (Ni) and cobalt (Co) loss could occur from acidic sulfate solution during partial neutralisation of synthetic nickel laterite pressure acid leach solutions (to pH 4 at 85 °C) was investigated. Knowledge of the avenues by which Ni and Co loss occurs will enable minimisation of valuable metal losses through optimisation of the partial neutralisation process. Precipitation of Ni and Co as their hydroxides did not appear to be a pathway by which metal loss occurred during partial neutralisation. Additionally, co-precipitation of Ni and Co with either Fe(III) or Al was not found to be a significant route for valuable metal loss. Adsorption onto freshly precipitated hydrous oxides of Al and Fe(III), as well as haematite, a major component of nickel laterite pressure leach discharge solids, appeared to be the primary route by which Ni and Co loss occurs during partial neutralisation. There was a preference for Co to adsorb onto haematite and ferric iron precipitates whilst Ni preferentially adsorbed onto Al precipitates. The molar ratio of Al to Fe(III) in the synthetic feed liquor was found to be a key variable controlling Ni and Co loss during partial neutralisation. Final Ni losses initially increased with increasing Al/Fe molar ratio in the feed, being at their highest in the absence of Fe(III) (10.7% Ni loss), and when the Al/Fe molar ratio in solution was unity (11.9% Ni loss), then decreased significantly when the Al/Fe ratio in the feed liquor was greater than or equal to 2 (2% Ni loss). Cobalt losses generally decreased with increasing Al/Fe ratio in solution except for in the presence of haematite where Co losses were 3.30%, confirming that Co adsorption onto haematite is a significant route by which loss of this valuable metal occurs during partial neutralisation.

Selective extraction and separation of Li, Co and Mn from leach liquor of discarded lithium ion batteries (LIBs)

Novel route has been developed to selectively extract lithium (Li), cobalt (Co) and manganese (Mn) from the leach liquor of discarded lithium ion batteries (LIBs) containing 1.4 g/L Cu, 1.1 g/L Ni, 11.9 g/L Co, 6.9 g/L Mn and 1.2 g/L Li. Initially, Cu and Ni were extracted by solvent extraction techniques using 10% LIX 84-IC at equilibrium (Eq.) pH 3 and 4.6, respectively. Subsequently, precipitation studies were carried out at different conditions such as pH, reaction time, precipitant concentration etc., to optimize the parameters for selective precipitation of Co from the leach liquor. Result showed that 99.2% Co was precipitated from the leach liquor (11.9 g/L Co, 6.9 g/L Mn and 1.2 g/L Li) after extraction of Cu and Ni in a range of pH 2.9 to 3.1 using un-diluted ammonium sulfide solution (10% v/v) as a precipitant at 30 °C, while only 0.89% Mn and 0.62% Li were co-precipitated. After Co precipitation, 98.9% Mn was extracted from the filtrate using 10% D2EHPA at equilibrium pH 4.5, and Li remained in raffinate. From the obtained purified solution, metals could be recovered either in a form of salt/metals by precipitation/ evaporation/ electrolysis method.

Combined use of tannic acid-type organic composite adsorbents and ozone for simultaneous removal of various kinds of radionuclides in river water

Tannic acid-type organic composite adsorbents (PA316TAS, AR-01TAS, PYRTAS, WA10TAS, WA20TAS, and WA30TAS), combined with hydrolyzed and sulfonated tannic acid (TAS) and porous-type strongly basic anion-exchange resin (PA316), benzimidazole-type anion-exchange resin embedded in high-porous silica beads (AR-01), pyridine-type anion-exchange resin (PYR), acrylic-type weakly basic anion-exchange resin (WA10), or styrene-type weakly basic anion-exchange resins (WA20 and WA30) for simultaneous removal of various kinds of radionuclides in river water were successfully synthesized. The adsorption behavior of twelve kinds of simulated radionuclides (Mn, Co, Sr, Y, Ru, Rh, Sb, Te, Cs, Ba, Eu, and I (I− and IO3−)) on these composite adsorbents has been studied in real river water at room temperature. PA316TAS adsorbents showed much higher distribution coefficients (Kd) for all metal ions. TAS structure has more selective adsorption ability for Mn, Co, Sr, Y, Cs, Ba, Eu, and IO3−. On the other hand, Y, Ru, Rh, Sb, Te, Eu, I (I− and IO3−) were adsorbed on both PA316 and TAS structures. To evaluate the validity of these mechanistic expectations, the respective chemical adsorption behaviors of Mn, Co, Sr, etc. and PA316TAS adsorbent were examined in river water ranging in temperature from 278 to 333 K. As was expected, one adsorption mechanism for Mn, Co, Sr, Cs, and Ba systems and two types of adsorption mechanisms for Y, Ru, Rh, Sb, Te, Eu, I (I− and IO3−) systems were observed. On the other hand, the precipitation of Mn, Co, Y, Ru, Rh, Te, and Eu was formed by ozonation for river water, that is, ozone can transform Mn, Co, Y, Ru, Rh, Te, and Eu ions into the insoluble precipitates. Hence, one straight line for Sr, Cs, Ba systems and two types of straight lines for Sb, I (I− and IO3−) systems were obtained in river water treated with ozone. The chromatography experiments of Cs, Sr, I (I− and IO3−) were carried out to calculate their maximum adsorption capacities. The obtained maximum adsorption capacities of Cs, Sr, and I− mixed with IO3− were 1.7 × 10−4 (Cs), 1.8 × 10−3 (Cs/O3), 7.8 × 10−5 (Sr), 5.6 × 10−4 (Sr/O3), 5.4 × 10−2 (I− and IO3−), 3.1 × 10−2 (I− and IO3−/O3) mol/g - PA316TAS. It was discovered that the maximum adsorption capacities of I− and IO3− for the composite adsorbent is unprecedented high and the capacity become much greater than an order of magnitude, compared with those of previous reports. This phenomenon suggests the formation of electron-donor-acceptor (EDA) complexes or pseudo EDA complex. Based on these results, it was concluded that the combined use of tannic acid-type organic composite adsorbents and ozone made it possible to remove simultaneously and effectively various kinds of radionuclides in river water in the wide pH and temperature ranges.

Insights into the Biogeochemical Cycling of Cobalt: Precipitation and Transformation of Cobalt Sulfide Nanoparticles under Low-Temperature Aqueous Conditions.

Cobalt sulfide precipitates, key phases in the natural biogeochemistry of cobalt and in relevant remediation and resource recovery processes, are poorly defined under low-temperature aqueous conditions. Here, we systematically studied Co (Fe) sulfides precipitated and aged in environmentally relevant solutions, defined by different combinations of pH, initial cobalt to iron ratios ([Co]aq/[Fe]aq), with/without S0, and the presence/absence of sulfate-reducing bacteria. The initial abiogenic precipitates were composed exclusively of amorphous Co sulfide nanoparticles (CoS·xH2O) that were stable in anoxic solution for 2 months, with estimated log K* values 1-5 orders of magnitude higher than that previously reported for Co sulfides. The addition of S0, in combination with acidic pH and elevated temperature (60 °C), resulted in recrystallization of the amorphous precipitates into nanocrystalline jaipurite (hexagonal CoS) within 1 month. In the presence of Fe(II)aq, the abiogenic precipitates were composed of more crystalline Co sulfides and/or Co-rich mackinawite, the exact phase being dependent on the [Co]aq/[Fe]aq value. The biogenic precipitates displayed higher crystallinity for Co sulfides (up to the formation of nanocrystalline cobalt pentlandite, Co9S8) and lower crystallinity for Co-rich mackinawite, suggestive of mineral-specific bacterial interaction. The revealed precipitation and transformation pathways of Co (Fe) sulfides in this study allows for a better constraint of Co biogeochemistry in various natural and engineered environments.

Pyrite chemistry: A new window into Au-Te ore-forming processes in alkaline epithermal districts, Cripple Creek, Colorado

Tellurium has a wide variety of applications, most importantly in the solar energy industry and is eco-toxicologically significant; however, the magmatic-hydrothermal processes causing the pronounced Te enrichment together with Au in some epithermal districts are still poorly constrained. Hydrothermal and alkaline magmatic activity in post-subduction environments are suggested to be a critical component in the evolution of this Te-rich sub-class of low-sulfidation epithermal deposits. Cripple Creek represents an example for a world-class low-sulfidation epithermal Au-Te anomaly in the continental crust. This area represents a natural laboratory to investigate the processes of ore-formation and Au-Te enrichment in alkaline igneous rock-hosted epithermal systems.Here, we present the first micro-analytical approach that combines petrographic observations with in situ LA-ICP-MS analyses and trace element mapping to define the key ore-forming processes of Au and Te in the Cripple Creek epithermal complex. Two main styles of mineralization can be distinguished: (1) low-grade Au disseminated pyrite-rich ores in the permeable brecciated host rocks and (2) high-grade quartz-fluorite veins rich in calaverite (AuTe2), coloradoite (HgTe), petzite (Ag3AuTe2), altaite (PbTe) and native Au.Pyrite trace element mapping revealed distinct variations and decoupling of elements (Au-Te) and element pairs (Au-As vs. Co-Ni) within and between different sites in the epithermal district. This is reflected by the concentric/growth zoning of these elements in pyrite that were interpreted to be caused by fluid boiling associated with the deposition of the low-grade disseminated host rock ores at temperatures between 220 and 350 °C leading to the precipitation of Au, As, Co and Ni from the liquid phase and the preferential partitioning of Te into the vapor phase. The subsequent condensation of the Te-rich vapors in metal-bearing meteoric waters led to the Te precipitation being decoupled from Au in the low-grade ores.The high-grade Au-Te mineralization was likely initiated by the influx of magmatically derived oxidized fluids. Subsequently, fluid temperatures dropped due to mixing with meteoric waters resulting in fluid boiling under low pressure conditions at shallower crustal levels (<1000 m) compared to the low-grade ores. Elevated fO2 minimized the loss of Te to the vapor phase and the strong boiling conditions at lower fluid temperatures (105–200 °C) caused the contemporaneous precipitation of Au and Te in the high-grade veins.

The influence of biologically produced sulfide-containing solutions on nickel and cobalt precipitation reactions and particle settling properties

Wastewater from mining and metallurgical activities provides a potential profit source for recovering leftover but valuable metals such as nickel (Ni) and cobalt (Co). For this, sulfide precipitation is an attractive option, although the cost of providing chemical sulfide and the poor settling of metal sulfides discourage its application. As an alternative, sulfide-containing solution (i.e. biogenic sulfide) can be produced on site by sulfate reducing bacteria that can utilize sulfate present in the wastewater, thus reducing reagent and transportation costs. Additionally, the various components in biogenic ‘sulfide’, i.e., bacterial cells, cell by-products and exopolymer may enhance the settling properties of Ni and Co sulfide, thus improving metal recovery. In this project, the effect of using chemical sulfide and four biogenic sulfide-containing solutions for Ni and Co precipitation and settling was evaluated. The biogenic sulfide-containing solutions were obtained from four bioreactors fed with volatile fatty acids (VFA), leachate from fermentation of municipal solid waste, ethanol and lactate, respectively. The results showed that VFA-fed biogenic sulfide enhances the Ni precipitation reaction as compared with chemical sulfide, whereas Co was effectively precipitated from solution (> 98%) regardless of the sulfide source and metal concentration. Settling extent of both metal sulfides reached up to 80–90% in lactate-fed biogenic sulfide, while <20% of the precipitates settled by reaction with chemical sulfide. Phosphate was the main component affecting particle settling whereas acetate and sulfate exhibited a smaller influence. This research highlights the importance of the different components from the biogenic sulfide-containing solutions in the precipitation and settling of Ni and Co precipitates, demonstrating enhanced prospects of metal recovery through biological sulfate reduction process.

Pronounced nanoindentation creep deformation in Cu-doped CoFe-based metallic glasses

By using nanoindentation techniques combined with atomic force microscopy, a pronounced creep behavior at ambient temperature as demonstrated by small creeping stress exponents was observed in (Co0·7Fe0.3)0.68B0·219Si0·051Nb0.05 metallic glass with 0.5 at.% Cu addition. Such obvious creep deformation is due to the precipitation of Co(Fe)-rich clusters induced by the chemical effect of Cu. It promotes the formation of the weakly bonded structure and thereby the generation of plenty of excess free volume during the nucleation and propagation of multiple shear bands in the process of deformation, which contributes to a steady creep behavior and large plasticity. Our work provides a microscopic understanding of creep behaviors in Cu-doped metallic glasses, which might also guide for improving the plasticity of these alloys.

Atomic-scale heterogeneity in large-plasticity Cu-doped metallic glasses

By using nanoindentation techniques combined with transmission electron microscope, wide-/small-angle X-ray scattering, and three-dimensional atom probe tomography, the sub-nanometer- to nanometer-length-scale structural heterogeneity due to the precipitation of Co(Fe)-rich clusters was observed in [(Co0.7Fe0.3)0.68B0.219Si0.051Nb0.05]100-xCux (x = 0.5) metallic glasses. Such short-range ordered structure promotes energy dissipation during deformation via regulating intrinsic elastic constants and hardness at the mesoscale, which contributes to the improved compressive plasticity of Cu-doped (Fe, Co)-based metallic glasses. Our work provides new evidence on atomic-scale heterogeneity in Cu-doped metallic glasses from the aspects of topological orders and microscopic mechanical responses.