Metal Resources Research Articles

Green Recycling Methods to Treat Lithium-Ion Batteries E-Waste: A Circular Approach to Sustainability.

E-waste generated from end-of-life spent lithium-ion batteries (LIBs) is increasing at a rapid rate owing to the increasing consumption of these batteries in portable electronics, electric vehicles, and renewable energy storage worldwide. On the one hand, landfilling and incinerating LIBs e-waste poses environmental and safety concerns owing to their constituent materials. On the other hand, scarcity of metal resources used in manufacturing LIBs and potential value creation through the recovery of these metal resources from spent LIBs has triggered increased interest in recycling spent LIBs from e-waste. State of the art recycling of spent LIBs involving pyrometallurgy and hydrometallurgy processes generates considerable unwanted environmental concerns. Hence, alternative innovative approaches toward the green recycling process of spent LIBs are essential to tackle large volumes of spent LIBs in an environmentally friendly way. Such evolving techniques for spent LIBs recycling based on green approaches, including bioleaching, waste for waste approach, and electrodeposition, are discussed here. Furthermore, the ways to regenerate strategic metals post leaching, efficiently reprocess extracted high-value materials, and reuse them in applications including electrode materials for new LIBs. The concept of "circular economy" is highlighted through closed-loop recycling of spent LIBs achieved through green-sustainable approaches.

Kinetics study of heavy metal removal from the lead smelting slag by carbothermic reduction: Effect of phase transformation

As an environmentally hazardous waste, the lead smelting slag was considered as a potential secondary resource of valuable metals (Zn, Pb, and Sn) if recycled. In this study the removal mechanism and kinetics of Zn, Pb, and Sn from the lead slag by carbothermic reduction at 1423–1473 K were investigated. Microstructure evolution of the pellets and phase transformation of heavy metals was analyzed by XRD and SEM/EDS. The kinetics behaviors of heavy metal volatilization were associated to the phase transformation. The results showed that Zn, Pb and Sn removal were controlled by the three-dimensional internal diffusion. Interestingly, the volatilization of Zn presented a consistent kinetics behavior, because the volatile phases of Zn were always metallic Zn in the whole reaction process. However, the volatilization of Sn and Pb conformed to a two-staged kinetics model. It was because that the nonvolatile polymetallic sulfides (Fe-Sn-Pb-S) and Fe-Pb-Sn alloy generated with metallic iron at a higher metallization degree, which hindered the internal diffusion of Sn and Pb. On the basic of this, a staged kinetics model of heavy metal removal was established, and the apparent rate constants and activation energies were determined.

Copper recovery from waste printed circuit boards by the flotation-leaching process optimized using response surface methodology

ABSTRACT Recycling of waste printed circuit boards (PCBs) receives increasing attention due to abundant metallic resources and significant environmental threats. This work proposes a process for copper recovery from PCBs by froth flotation and oxidation leaching. Copper grade is improved from 38.70% to 68.34% with the recovery of 88.76% by froth flotation, and froth flotation is significantly influenced by copper liberation and particles dispersion of PCB powders. Process variables of oxidation leaching are examined by response surface methodology (RSM). A reliable mathematical model is obtained to predict the response as a function of independent variables and their interactions. Oxidation leaching is remarkably influenced by experimental variables, and the interactions between sulfuric acid and hydrogen peroxide are significant. Optimum conditions are achieved as sulfuric acid 1.0 mol/L, hydrogen peroxide 17%, temperature 50°C, and time 234 minutes, and the maximum leaching ratio of Cu is up to 99.94%, indicating that oxidation leaching is an effective method for Cu recovery from PCBs. Implications: Recycling of waste printed circuit boards (PCBs) receives increasing attention due to abundant metallic resources and significant environmental threats. This work proposes a novel process for copper recovery from PCBs by froth flotation and oxidation leaching. Froth flotation is efficient to enrich copper in metal fractions. Process variables of oxidation leaching are examined by response surface methodology (RSM). A reliable mathematical model is obtained to predict the response as a function of independent variables and their interactions. The froth flotation-oxidation leaching process is practicable and effective for copper recovery from waste printed circuit boards. This study significantly contributes to recycling metal resources from waste PCBs. We believe that this work will attract a broad readership and lead others to follow our approach.

Study on the Refining Conditions of Nickel Pig Iron for High Purity Nickel Matte Production

Nickel has been known to be the most important metallic resource, which has been used in various products, such as multi-layer ceramic capacitors, Li-ion batteries, heat-resistance super alloys. Those Ni resources have various types such as metallic nickel, ferronickel alloy, nickel matte, and nickel sulfate depending on the situation. In a production route of high purity nickel matte from ferronickel, which had been implemented many decades ago, a large amount of by-product, as well as relatively high operational cost, have been recently drawing attention. To resolve arisen problems, nickel pig iron can be suggested as a low-cost raw material. The possibility of upgrading nickel pig iron by removal of Fe and enrichment of Ni was investigated by lab-scale oxidation experiments. It was found that major impurities like C and Si should be removed before Fe oxidation initiates. And decarburization and desiliconization of nickel pig iron were enhanced by oxygen injection, compared with other blowing manners. The slag conditions for effective Fe oxidation were discussed using thermodynamic calculation and oxygen blowing tests. Conclusively, the continuous addition of CaO during oxygen blowing enables the formation of liquid slag and further Fe oxidation. In the case of Fe2O3-SiO2 based slag, liquid slag seems to be limited by MgO dissolution from refractory

Stepwise extraction of Fe, Al, Ca, and Zn: A green route to recycle raw electroplating sludge

Electroplating sludge is a hazardous waste produced in large quantities in the electroplating industry during production. It is rich in heavy metal resources and can be recovered as value-added heavy metal products. To recover Zn in electroplating sludge, Fe/Al/Ca impurities were effectively removed as hematite, boehmite, and calcium sulfate, respectively, via a facile hydrothermal method with reduction of nitric acid by addition of glucose. After the sludge was dissolved in nitric acid, the generated solution contained 6.1 g/L of Zn, 2.2 g/L of Fe, 2.5 g/L of Al, and 2.9 g/L of Ca. First, approximately 100% Fe was extracted as hematite nanoparticles containing 94.6 wt% Fe2O3 after the solution was treated at 190 °C for 6 h. Second, when the temperature was elevated to 270 °C, nearly 99% Al was isolated as boehmite particles containing 95.2 wt% Al2O3. Third, more than 98% Ca was removed as anhydrite, which contained 95.9 wt% CaSO4, by adding sulfuric acid. During the steps, the total loss of Zn was less than 3%, and 5.75 g/L of residual Zn was recovered as zincite containing 92.2 wt% ZnO by adjusting the pH to 8. The dissolved Fe, Al, and Ca impurities were successfully removed as purified hematite, boehmite, and anhydrite, respectively, through the stepwise separation method by adjusting reaction temperatures and pH. The high content of Zn in the electroplating sludge was finally purified as zincite.

Decreasing the Power-Clock Resonant Signal Central Voltage as a Mean for Power Reduction in Integrated Power and Clock Distribution Networks

Background/Objectives: Density, performance, and design complexity of integrated circuits are rapidly increasing specifically in 3-D integration where multi-plane synchronization is required. The power and clock distribution networks consume a large portion of the limited on-chip metal resources. In order to reduce the metal overhead associated with the power, global clock, and local clock distribution networks, the concept of an integrated power and clock distribution network (IPCDN) was investigated and correct functionality of combinational and sequential elements verified. This study discusses potential power savings in IPCDNs achieved by reducing the central voltage at which the signal oscillates. Methods/Statistical analysis: In this paper, an IPCDN with differential power-clock signals centered at half the supply voltage is proposed to further reduce the power consumption. The elements of the proposed scheme including the LC differential power-clock driver, clamping circuit, clock buffer, and voltage doubler have been simulated using Tanner 0.25 um CMOS technology at a frequency of 50 MHz and a supply voltage of 2.5 V. Findings: Simulation results indicate that the proposed scheme achieves 75.32% and 76.47% power reduction in the LC differential powerclock driver and clock buffer, respectively. The effects of process, voltage supply, and temperature (PVT) variations on the proposed scheme were also investigated. Discussion: The IPCDN has a large capacitance and is heavily loaded, thus reducing the central voltage of the resonant sinusoidal signal flowing in this network enables significant reduction in power consumption. Novelty/Applications: The proposed scheme enables power reductions in the LC differential power clock driver and clock buffer. The effects of process, voltage supply, and temperature (PVT) variations on all circuit elements of the proposed scheme was investigated. Keywords: resonant clocking; power reduction; routing complexity; LC clock driver; clock buffer; clamping circuit; voltage doubler Density, performance, and design complexity of integrated circuits are rapidly increasing specifically in 3-D integration where multi-plane synchronization is required. The power and clock distribution networks consume a large portion of the limited on-chip metal resources. In order to reduce the metal overhead associated with the power, global clock, and local clock distribution networks, the concept of an integrated power and clock distribution network (IPCDN) was investigated and correct functionality of combinational and sequential elements verified. This study discusses potential power savings in IPCDNs achieved by reducing the central voltage at which the signal oscillates. Methods/Statistical analysis: In this paper, an IPCDN with differential power-clock signals centered at half the supply voltage is proposed to further reduce the power consumption. The elements of the proposed scheme including the LC differential power-clock driver, clamping circuit, clock buffer, and voltage doubler have been simulated using Tanner 0.25 um CMOS technology at a frequency of 50 MHz and a supply voltage of 2.5 V. Findings: Simulation results indicate that the proposed scheme achieves 75.32% and 76.47% power reduction in the LC differential powerclock driver and clock buffer, respectively. The effects of process, voltage supply, and temperature (PVT) variations on the proposed scheme were also investigated. Discussion: The IPCDN has a large capacitance and is heavily loaded, thus reducing the central voltage of the resonant sinusoidal signal flowing in this network enables significant reduction in power consumption. Novelty/Applications: The proposed scheme enables power reductions in the LC differential power clock driver and clock buffer. The effects of process, voltage supply, and temperature (PVT) variations on all circuit elements of the proposed scheme was investigated. Keywords: resonant clocking; power reduction; routing complexity; LC clock driver; clock buffer; clamping circuit; voltage doubler

How precious metal and energy resources interact with clean energy stocks? Fresh insight from the novel ARDL technique.

To boost the stability of economic and financial aspects along with the apprehensions for sustainability, it is important to promote the development of clean energy stocks around the globe. In the current research, the researchers have examined the impact of oil prices, coal prices, natural gas prices, and gold prices on clean energy stock using the autoregressive distribution lag (ARDL) approach from the year 2011 to the year 2020. The result of daily data analysis specifies that in the long as well as in the short run, gold prices, oil prices, and coal prices have a positive and significant effect on clean energy stock. On the other side, natural gas prices in the long as well as in the short run have a negative and significant effect on clean energy stock. So, the empirical analysis of our study is of interest to investors at an institutional level who aim at detecting the risk associated with the clean energy market through proper financial modeling. Besides, this study opens up a new domain to sustain financial as well as economic prospects by protecting the environment through clean energy stock as the investment in clean energy stocks results in producing a substantial effect on the economy and the environment as well.

Milliampere-level direct current enhance cyanogenic capability of bacteria during the bioleaching of precious metals from waste printed circuit boards

For the conservation and sustainable utilization of metallic resources, recovering precious metals from the vast quantity of waste printed circuit boards is an attractive avenue. Bioleaching has been proved as an environment-friendly and suitable recovery technology. However, the limited cyanogenic capability restricts the industrialization of this technology. To break this bottleneck, in this paper, an innovative bioleaching technology assisted by milliampere-level direct current was developed to enhance cyanogenic capability. Experimental results indicated 10 mA current was the most beneficial for cyanide production. At 10 mA, the cyanide concentration reached 5.05 mg/L, 1.48 times that of without electric current. With the assistance of milliampere-level direct current, the total energy required for the reaction from glycine anion to cyanide was decreased by 101.81 kcal/mol. Meanwhile, the added direct current reduced the relative abundance of Pseudomonadaceae but enriched Enterobacteriaceae. Clusters of orthologous groups function classification revealed that some functions involved in cyanide production such as secondary metabolites biosynthesis, transport and catabolism were more powerful. This work proposes a novel approach to break the bottleneck of low cyanogenic capability in bioleaching technology, providing crucial scientific information for the industrialization of bioleaching.

A provenience study of Bronze Age metal objects from the Hami Basin, Xinjiang, China

Lead isotopic analysis on metals of the Bronze Age of Hami Basin (1800-400 BCE) principally focus on the early sites such as the Tianshanbeilu cemetery and Liushugou Site. Opinions on their provenience are wildly divergent. This research presents 29 lead isotope data of metals from Wupu cemetery (1000-400 cal BCE) as an important site from the late period and ten from Tianshanbeilu cemetery as well as their chemical composition and metallographic structure. Combined with existing data, this article comprehensively discusses the possibly existing circulation network of metal resources between the Hami Basin and the other three areas, namely the southern Altai Mountains, the Hexi Corridor, and the West Tianshan Mountains during the Bronze Age, and provides a new understanding of the role played by the Hami Basin in the Bronze Age as one of the cultural passageways linking the eastern Eurasian steppe and the Hexi Corridor.

Prospect for expansion and replenishment of rare metal resources and reserves in Eastern Kazakhstan

The main rare metal-bearing structures in Eastern Kazakhstan are granitoid belts formed in the Hercynian cycle of tectogenesis in the post-collisional (orogenic) geodynamic environment of the Permian time and confined to the continental blocks of siallitic high-level. The geotectonic position of the Kalba–Narym rare metal granitoid belt in the geological structure of the Greater Altai is considered. The known rare-metal pegmatite deposits (Ta, Nb, Be, Li, etc.) are spatially and genetically related to Kalba granites (P1). The richest ore-bearing are granite massifs formed in the mobile tectonic environment and under unbalanced P–T conditions. The distribution of rare alkalis in granitoids of the Hercynian evolutionary series is given. The forecast estimate of prospects is associated with the study of hidden granite massifs on the northwestern flank of the belt, identified based on the geological and geophysical data. The forecasting criteria are the intensive alteration of the above-intrusive zone (granitization, greisenization, silicification), direct signs of tin–tungsten mineralization on ground surface, identification of ongonite-like dikes and rare metal minerals in metasomatites from the results of electron microscopy. The estimation of the prospects of nontraditional tin–lithium–tantalum mineralization associated with albitized and greisenized granites is given. It is recommended to undertake deep mineralogical mapping of the closed reserved areas. The further geological exploration should be aimed at expansion of mineral resources and reserves for rare metal production.The study was supported by the Committee of Science of the Ministry of Education and Science of the Republic of Kazakhstan, Contract No. 120 dated 1 June 2020, Registration No. 0120RK00135, and Grant IRN AR08856325.

Porphyry CU deposits in the Central Andes of Argentina: An overview

Porphyry Cu deposits are the world's most important source of Cu and the Central Andes of South America hold some of the largest Cu resources worldwide. In Argentina many porphyry-type deposits and prospects with different degrees of exploration straddle along ~1500 km of the Central Andes. The review and analysis of the tectono-magmatic, metallogenic and economic data of the better-known deposits and prospects allow to define the controls of porphyry-type mineralization and the metallogenic epochs and belts which in turn indicate the potential for porphyry-type mineralization in some relatively poorly explored segments of the Central Andes.Slab shallowing (particularly linked to the subduction of aseismic ridges) and associated eastward arc migration/expansion appears to be a favorable geodynamic scenario for Paleozoic and Cenozoic mineralizing magmatism which show variable adakitic signatures probably as a result of a progressive crustal thickening. In this context the V/Sc and especially the Sr/Y ratios are a useful tools for assessing magma fertility. Major WNW-trending deep crustal pre-Andean structures controlled the inland migration of the magmatism and are a first order control on porphyry emplacement during these epochs of magmatic activity.There are five favorable metallogenic epochs linked to the arc magmatism in Argentina: Permian, Upper Cretaceous-Eocene, late Eocene-early Oligocene, late Oligocene-early Miocene and Miocene-Pliocene. The Permian and Upper Cretaceous-Eocene metallogenic epochs are represented by a small number of deposits with low metal (Cu–Mo–Au) content; however, the extension of the magmatism of both epochs suggests they are favorable for further exploration. The late Eocene–early Oligocene magmatism involves few deposits but formed the second largest known copper resource in Argentina. The Miocene-Pliocene magmatism, particularly between ~11 and 6 Ma, generated the largest porphyry-type deposits with the greatest metal resources. Based on the available information ten metallogenic belts are outlined: 1) Permian Puna-Frontal Cordillera/Neuquén basement, 2) Upper Cretaceous–Eocene Neuquén, 3) late Eocene-early Oligocene, 4) late Oligocene-early Miocene, 5) middle Miocene Puna-Frontal Cordillera, 6) middle Miocene Precordillera, 7) late Miocene Cordillera, 8) late Miocene-Pliocene Cordillera, 9) late Miocene-Pliocene Northern Sierras Pampeanas, 10) late Miocene-Pliocene Famatina. These ten metallogenic belts accumulate 74.21 Mt Cu, 1.70 Mt Mo, 2160.66 t Au and 23,876.71 t Ag of known resources and approximately 239 Mt Cu, 6.4 Mt Mo, 4240 t Au and 77,900 t Ag contained in undiscovered deposits. The Miocene belts are the most endowed, confirming their economic importance as well as their prospectivity for exploration. The largest total known resources are hosted by the late Miocene belt in the Frontal Cordillera, followed by the late Eocene-Early Oligocene one and the Miocene-Pliocene belt in the Sierras Pampeanas. The continuation of the late Miocene-Pliocene Cordillera belt that extends from Los Bronces and El Teniente in Chile, further south into Argentina, is here considered the most prospective underexplored belt.

Integrating high-efficiency oxygen evolution catalysts featuring accelerated surface reconstruction from waste printed circuit boards via a boriding recycling strategy

Converting electronic wastes into high-efficiency energy conversion catalysts is a win-win strategy in addressing the metal resources shortage and sustainable energy challenges. Herein, a facile boriding strategy is developed to directly convert the leachates of waste printed circuit boards into magnetic mixed metal borides (FeNiCuSnBs) for oxygen evolution reaction (OER) catalysts. Via the boriding process, a metal cation recovery rate of 99.78 %, 99.98 %, 99.96 %, and 99.49 % has been attained for Fe, Ni, Cu, and Sn, respectively. The obtained catalysts with a higher ratio of Ni and Fe show better OER performance. The optimal FNCSB-4 attains 10 mA cm−2 at a low overpotential of 199 mV, as well as good stability in alkaline solution. Remarkably, FNCSB-4 represents a record‐high activity among waste-derived OER electrocatalysts. In-depth study suggests that the superior OER performance is mainly owing to accelerated surface self-reconstruction by B/Sn co-etching under OER potential region, and the newly formed multimetal (oxy)hydroxides act as the active species for OER. Additionally, the efficient mass/charge transfer, the amorphous feature, and hierarchical structure also benefit OER. Apart from providing an insight into the correlation between surface self-reconstruction and OER activity of multimetal boride-based catalysts, this study also offers a general strategy for the high-efficiency recovery and advanced energy-driven applications of critical metals from other urban mines in a sustainable and environment-friendly approach.

Re‐Os Isotopic Age of Molybdenite of the Jingren Deposit and its Mineralogical Significance of Magnetite, Pyrite and Chalcopyrite

AbstractThe Jingren deposit is part of the Qimantage metallogenic belt within the eastern Kunlun orogenic belt, the largest metallogenic belt in Qinghai Province, northwestern China. Exploration data show that the metal resources of the Jingren deposit are greater than 93000 t in a mining area of 76.15 km2, which indicates significant exploration potential in the near future. Three W–E‐trending faults, F1‐3, dominate the extension of the mineralization zone, which consists of chalcopyrite, pyrite, magnetite, galena, sphalerite, and molybdenite as well as bismuth‐bearing minerals. The deposit contains a large amount of late Triassic intrusive rocks, however, previous research did not reach a consensus on the timing or the origin of the mineralization owing to a lack of geochronological data and poor exposure conditions. In the present study, Re‐Os isotopic dating from six molybdenite samples collected from a borehole of the granodiorite in the Jingren deposit using negative thermal ionization mass spectrometry (NTIMS) showed 187Re and 187Os concentrations of 0.26–4.40 ppm and 1.03–16.46 ppb, respectively, with an initial 187Os/188Os value of 0.06 ± 0.19. This proves that the Jingren deposit has a metallogenic age of (225 ± 4) Ma and is the product of united mineralization of the Qimantage metallogenic belt and that the Jingren deposit might actually be an Indosinian metallogeny. In addition, the Re content of these samples, at 0.42 ppm to 7.00 ppm shows that the mineralization was derived mainly from a crustal source. Furthermore, electron probe microanalysis (EPMA) conducted on chalcopyrite obtained from 22 metallic mineral samples revealed (Fe + Cu)/S ratios of 1.801–1.947 with an average of 1.852, which is lower than the ideal value (1.875). Besides, the main ore body formed in a relatively higher temperature environment than the surrounding rocks in the Jingren deposit. These data indicate that the Jingren deposit formed in a metallogenic environment at lower temperature. Moreover, according to the TiO2‐Al2O3‐(MgO + MnO) and TiO2‐Al2O3‐MgO genetic classification diagram for magnetite, the Jingren deposit most likely belongs to the skarn family. In addition, the Co‐Ni‐As genetic classification diagram of the pyrite indicates sedimentary and skarn genetic characteristics.

Technologies for metal recycling from electrical - electronic wastes

Wastes from electrical - electronic equipment (WEEE) are of huge concerns worldwide. With the decreasing life cycle of most electrical - electronic equipment (EEE), the WEEE growth rate is fast, about 3÷5% annually. This is considered as the fastest growing waste stream among municipal wastes. WEEE contains, in addition to plastic, glass etc., high contents of base metals and precious metals. They are regarded as potential secondary resources of metals in addition to primary resources of metals from metallic ores. Over the past decades, many metal recycling technologies from WEEE have been developed including physical separation processes and chemical extraction processes. This article summarizes the characteristics, recycling principles, separation processes and optimal operating conditions of the world's most currently common technologies for metal recycling from WEEE. So that one can derive new directions for metal recycling from electrical - electronic wastes in the Vietnam case.

Zinc oxide coated regenerated spent FCC catalyst for water purification

Introduction: Zeolites are microporous aluminosilicates, commonly used as commercial adsorbents and catalysts. As an adsorbent, zeolite can adsorb gram-positive bacteria when compared with gram-negative bacteria (1,2). Ultrafine zinc oxide nanoparticles in colloidal medium is toxic to E. coli bacteria (3). ZnO-coated zeolite adsorbent can effectively remove of humic acid and E. coli from water when compared to zeolite adsorbent (4-5). The spent FCC (SFCC) catalyst is very harmful to the human health by being absorbed mainly into the respiratory tract and lungs due to its tiny particles of size 60-100 micrometer (1). Most of the spent FCC catalysts are currently disposed as landfills, which leads to the wastage of valuable metal resources and the environmental pollution. In this work the spent zeolite catalyst is regenerated and coated with zinc oxide and this zinc oxide coated regenerated spent FCC catalyst (ZOCRSC) is used to remove E. coli from water. Methods: In this work, decoking is done to burning off the deposited carbon by roasting in air at 550°C for 2 hours. Then SFCC catalyst is leached with HCl and oxalic acid. Activated SFCC catalyst, obtained as a leaching residue is separated. Zinc oxide is coated on the regenerated catalyst to develop zinc oxide coated zeolite adsorbents. Coating procedure follows activated catalyst modified by HNO3 and then Zn(NO3)2 solution. To characterize crystal structure of zeolite and ZOCRSC, XRD, SEM, and BET analysis were carried out. The water from the treatment plant after secondary treatment was used for the experiments and the E. coli content was estimated using plate counting technique. ZOCZ is added to the E-coli containing water and after proper mixing the suspension is allowed to settle. Sample is collected from treated water at different intervals for determining E. coli content. The treatment procedure was also done using the spent coated sample, acid activated sample and spent FCC catalyst and are used as a comparison with ZOCZ. Results & Discussions: The XRD pattern shows that the ZOCRSC exhibited similar characteristic diffraction peaks to that of the uncoated samples which indicates that the modification did not affect the mineralogy of the zeolite and in addition it also exhibited similar characteristic diffraction peaks to those of ZnO. Thus, the XRD pattern and the SEM images of ZnO coated spent catalyst and ZnO coated regenerated catalyst shows that coatings of ZnO on zeolites were done effectively. The surface area and pore volume of zinc oxide coated regenerated spent FCC catalyst is determined from BET analysis. The removal of E. coli from water was quantified by plate counting. The E. coli count of the untreated water sample is 560 cfu/ml and treated sample after 30 minutes is less than 1 cfu/ml. Water treated using spent FCC catalyst without any modification did not show any change in the E. coli count. The acid activated catalyst and spent FCC catalyst coated with ZnO reduce the E. coli content in the water to 11 cfu/ml and 6 cfu/ml respectively after 90 minutes. Conclusions: ZnO coated regenerated spent FCC catalyst is developed from waste spent catalysts is utilized for the removal of E. coli from water. The ZOCRSC removes E. coli effectively when compared with spent FCC catalyst coated with ZnO, acid activated catalyst, and spent FCC catalyst in a short period. The spent FCC catalyst coated with ZnO cannot be directly used for treating purpose as it contains various contaminant metals which should not be present in treated water. Keywords: Escherichia coli, Spent FCC catalyst, Zinc oxide, ZOCRSC

Elasticity of substitution and biased technical change in the CES production function for China's metal-intensive industries

To achieve sustainable and green development, it is imperative for China, as the world's major metal consumer, to improve utilization efficiency and conservation of metal resources. Thus, understanding the industrial endogenous growth patterns of China regarding metal utilization and technical change becomes the prerequisite. Therefore, this paper regards metal as one of production factors nested with capital and labor, employs normalized supply-side system approach to estimate the elasticity of substitution in constant elasticity of substitution (CES) function and analyzes technical change bias based on the analytical framework built in this paper. Results show that: the optimal nesting structure for most metal-intensive industries are metal-capital composite nested with labor. And the metal input is less efficient than capital or labor in all metal-intensive industries. The technical change biases for metal-intensive industries are diversified, but only metal mining industries and heavy machinery manufacturing industries tend to save metal when expanding the production effectively. Targeted suggestions are made per industry according to the heterogeneity of production factors allocation and technical change biases.

Development of Jacketing Machine

Flat Belt is manufactured almost all over the world. In the Transmission Industries, Flat Belt is almost available in every part. In modern trend demand has been significantly increased. To fulfil the increased demand for flat belt, jacketing operation of flat Belt must be paced up. In traditional jacketing processes which are carried out manually take more time, labour work and also provide damage to industry growth. To overcome this and to minimize stress on workers, an attempt has been made to design a jacketing machine for flat belt, which is simple in design and can be handled by the common man. The demand for a flat belt jacketing machine is higher and it is time to respond to the problem raised. Designing and fabricating such types of functional machines is important to save money instead of investing money and time buying labor and conventional tool. Since metal resources are declining and their products are very expensive as compared to rubber, it’s preferable to use Rubber flat belts rather than using chains for transmission. As per the studies, it is easier and economical to use belt drives replacing chain drives and it is good for the future without disturbing the ecosystem. Study shows that while analyzing the force and power for machines the designer takes the help of analysis software. The cost of software for analysis is high. So there is requirement to find simple formula. In this paper the various theories regarding bending are reviewed, formulae for force and power calculation are collected and finally a case study is taken where we have put together all the results of these formulae. Our main concern is to reduce the human effort required in jacketing of flat belt and also to save the time, labour work, lead time, and move towards the partial automation. The machine has been designed and developed to minimize the cost of production and increase the efficiency.

Genesis of the Bieyesamas Monzogranite of the Altay Mountain, Xinjiang, Northwestern China, and Its Rare Metal Resource Potential

Lying in the Altay Orogenic Belt in Xinjiang, Northwestern China, the Bieyesamas monzogranite pluton is located in the North Altay Terrane. It is one of the important granitic batholiths with a large amount of rare metal pegmatite dikes. According to LA-ICP-MS zircon U-Pb isotopic dating, the 206Pb/238U weighted average age of the Bieyesamas monzogranite is 451.1 ± 5.1 Ma ( MSWD = 6.0 ), indicating the formation age of Late Ordovician. The Bieyesamas monzogranite has secondary minerals such as garnet and tourmaline. The geochemical analysis shows that the pluton is characterized by high SiO2 (70.45%~75.44%), Al2O3 (14. 04%~17.14%), potassium and alkaline ( K 2 O = 4.20 % ~ 4.78 % , N a 2 O + K 2 O = 7.90 % ~ 8.99 % ), A/CNK (1.16~1.28), and high corundum (2.33%~5.08%) being found in CIPW standard minerals, belonging to high-K calc-alkaline peraluminous series. The pluton is enriched in LREE, depleted in HREE ( LREE / HREE = 5.99 ~ 9.65 ), with obviously negative Eu anomaly ( δ Eu = 0.44 ~ 0.60 ), while the trace elements are characterized by Rb, K, Nb, Ta, Hf, and U enrichment and Ba, Sr, Ti, and Zr depletion, as well as with high differentiation index ( DI = 93.24 % ). Zircon ε Hf t values range from 2.89 to 7.69, with the corresponding two-stage model ages ( T DM 2 ) of 941~1257 Ma. The mineral assemblage, geochemical characteristics, and zircon Hf isotope indicate the pluton experienced the highly fractionated process and belongs to highly fractionated S-type granite, which was formed by partial melting of the Meso- to Neoproterozoic crustal material. In the Bieyesamas monzogranite, the average contents of rare metals are obviously higher ( Li = 550 × 10 − 6 , Be = 10.18 × 10 − 6 , Nb = 18.91 × 10 − 6 , Ta = 2.14 × 10 − 6 , Rb = 500 × 10 − 6 , and Cs = 149.9 × 10 − 6 ) than the other rocks and Clark values of crust, which indicates that the Bieyesamas pluton has the enrichment potential of rare metals. The metallogenic geological conditions are superior in the Bieyesamas area of the Altay Mountain, and rare metal deposits and ore spots are widely distributed. In particular, the newly discovered rare metal deposits are characterized by large-scale mineralization, high grade and industrial utilization value, etc. It is preliminarily predicted that they have reached the medium-scale deposits. Therefore, the Bieyesamas area is one of the key areas for rare metal prospecting breakthroughs in the future, with great potential for rare metal mineral resources.

Chromium-Catalyzed Cross-Coupling Reactions by Selective Activation of Chemically Inert Aromatic C–O, C–N, and C–H Bonds

AbstractTransition-metal-catalyzed cross-coupling has emerged as one of the most powerful and useful tools for the formation of C–C and C–heteroatom bonds. Given the shortage of resources of precious metals on Earth, the use of Earth-abundant metals as catalysts in developing cost-effective strategies for cross-coupling is a current trend in synthetic chemistry. Compared with the achievements made using first-row nickel, iron, cobalt, and even manganese catalysts, the group 6 metal chromium has rarely been used to promote cross-coupling. This perspective covers recent advances in chromium-catalyzed cross-coupling reactions in transformations of chemically inert C(aryl)–O, C(aryl)–N, and C(aryl)–H bonds, offering selective strategies for molecule construction. The ability of low-valent Cr with a high-spin state to participate in two-electron oxidative addition is highlighted; this is different from the mechanism involving single-electron transfer that is usually assigned to chromium-mediated transformations.1 Introduction2 Chromium-Catalyzed Kumada Coupling of Nonactivated C(aryl)–O and C(aryl)–N Bonds3 Chromium-Catalyzed Reductive Cross-Coupling of Two Nonactivated C(aryl)–Heteroatom Bonds4 Chromium-Catalyzed Functionalization of Nonactivated C(aryl)–H Bonds5 Conclusions and Outlook

Status of Recovery of Strategic Metals from Spent Secondary Products

The need to drive towards sustainable metal resource recovery from end-of-cycle products cannot be overstated. This review attempts to investigate progress in the development of recycling strategies for the recovery of strategic metals, such as precious metals and base metals, from catalytic converters, e-waste, and batteries. Several methods for the recovery of metal resources have been explored for these waste streams, such as pyrometallurgy, hydrometallurgy, and biohydrometallurgy. The results are discussed, and the efficiency of the processes and the chemistry involved are detailed. The conversion of metal waste to high-value nanomaterials is also presented. Process flow diagrams are also presented, where possible, to represent simplified process steps. Despite concerns about environmental effects from processing the metal waste streams, the gains for driving towards a circular economy of these waste streams are enormous. Therefore, the development of greener processes is recommended. In addition, countries need to manage their metal waste streams appropriately and ensure that this becomes part of the formal economic activity and, therefore, becomes regulated.