Optimization of copper extraction for bioleaching of complex Cu-polymetallic concentrate by moderate thermophiles

Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.

Microstructure and mechanical properties of lightweight Ti_(3)Zr_(1.5)NbVAl_(x)(x=0,0.25,0.5 and 0.75) refractory complex concentrated alloys

Combining high strength and good ductility is an urgent requirement for traditional structural materials,but yet a challenge.Newly emerging ductile Ti_(3)Zr_(1.5)VNbAl_(x)(x=0,0.25,0.5,0.75) refractory complex concentrated alloys(RCCAs) with high specific strength were designed and synthesized via vacuum arc-melting.Alloying effects of Al on microstructure and mechanical properties were systematically investigated.It was found that the phase composition in this alloy system changes from the single disordered body-centered cubic(BCC) phase to a nano-scale mixture of co-continuous disordered BCC and ordered B2 phases with the increase of Al concentration.This structure transition results in a remarkable increase in the yield strength of the RCCAs,i.e.,from 790 to 1118 MPa,leading to a superior specific yield strength of 199.4 MPa cm^(3)g^(-1)for the Al0.75 alloy,meanwhile,the tension plasticity maintained at~10%.TEM observation demonstrates that cell-forming structure and HDDWs induced by wave slip play a crucial role of considerable plasticity in Al0.25 alloy,whereas in Al0.5 alloy,microbands induced by planar slip dominant deformation behavior.The current work is important not only for providing novel high strength and tough structural materials with low density,but also sheds light on designing highperformance lightweight alloys with tunable microstructure.

Machine learning of phases and mechanical properties in complex concentrated alloys

The mechanical properties of complex concentrated alloys(CCAs)depend on their formed phases and corresponding microstructures.The data-driven prediction of the phase formation and associated mechanical properties is essential to discovering novel CCAs.The present work collects 557 samples of various chemical compositions,comprising 61 amorphous,167 single-phase crystalline,and 329 multiphases crystalline CCAs.Three classification models are developed with high accuracies to category and understand the formed phases of CCAs.Also,two regression models are constructed to predict the hardness and ultimate tensile strength of CCAs,and the correlation coefficient of the random forest regression model is greater than 0.9 for both of two targeted properties.Furthermore,the Shapley additive explanation(SHAP)values are calculated,and accordingly four most important features are identified.A significant finding in the SHAP values is that there exists a critical value in each of the top four features,which provides an easy and fast assessment in the design of improved mechanical properties of CCAs.The present work demonstrates the great potential of machine learning in the design of advanced CCAs.

Microstructural Evolution of Co_(35)Cr_(25)Fe_(30)Ni_(10) TRIP Complex Concentrated Alloy with the Addition of Minor Cu and Its Effect on Mechanical Properties

The influences of minor Cu addition(2 and 4 at.%)on the microstructural evolution and room-temperature mechanical property of metastable Co_(35)Cr_(25)Fe_(30)Ni_(10)are systemically investigated in the present study.The results indicate that the thermally induced hexagonal close-packed(HCP)phase is absent when Cu was added,due to the increase in stacking fault energy(SFE).The 2%-Cu-added alloys showed the largest total elongation of 69%among the three alloys.With the addition of Cu content reaching 4 at.%,heterogeneous grain structures composed of coarse grains(~9μm)and fine grains(~4μm)and Cu-rich precipitates near the grain boundary are observed,showing the highest yield strength.Additionally,the segregation state of Cu was quantitatively characterized by electron probe microanalysis(EPMA).And effects of Cu addition on microstructures and tensile properties of(Co_(35)Cr_(25)Fe_(30)Ni_(10))_(100-x) Cu _(x) are also discussed.The findings are beneficial to comprehensively understand the Cu-containing complex concentrated alloys.

Pressure Oxidative Leaching of Complex Sulphide Concentrate

The presented results are related to the leaching of Pb-Zn-Cu-Fe sulphide concentrate, obtained from barite-sulphide ores, under the elevated temperatures and pressures in an autoclave. The leaching process was performed using the sulphur acid solution with the oxygen addition for the separation of the targeted metals from the polymetallic concentrate. In this process influences of various parameters were discussed and then correlated to the leached metals, zinc, copper and iron. Zinc, copper and iron were dissolved in a solution, while lead remained as insoluble in the leach residue. The best leaching results were determined under the temperature of 210 ℃ during the 240 min. Obtained leaching degrees were 98% zinc, 95% copper and 96% iron.

An investigation of oxygen pressure acid leaching of Gacun complex Cu-Pb bulk concentrate

The treatment of the Gacun complex Cu-Pb bulk concentrate with high Zn,Ag,etc.,by oxygen pressure acid leaching was studied.The pri-mary copper and leadminerals in the concentrate are tetrahedrite and galena.The treatment of tetrahedrite was rarely studied,and most of silver occurred in themineral too.The optimum operating parameters of oxygen pressure acid leaching were established by conditional tests.Under these parameters,the result of pilot scale test showed that the leaching percentages of copper and zinc were separately as high as 98.9 wt.% and 94.9 wt.%,while lead and silver were transformed into sulfate and sulfide precipitations,respectively.The copper and zinc in lixivium were reclaimed by extraction-electrowinning and purification-electrowinning,respectively,and the lead and silver in the residue were reclaimed separately by carbonate transformation-silicofluoric acid leaching and thiourea leaching.

Thermodynamic simulation of complex Pb-Bi concentrate oxidative bath smelting process

The element partitioning in a Pb-Bi concentrate oxygen-rich bath smelting process was studied using thermodynamic equilibrium simulation method. Effects of oxygen to feed ratio(OFR) and sulfur dioxide partial pressure(pSO2) on the partitionings of Bi, Pb, As, Sb, Cu and Ag were analyzed and compared with industrial data. The results suggested that the optimal OFR was between 6.3 and 6.8 kmol/t to maximize Bi, Pb, Cu and Ag partitioning in the metal phase. Further increase of OFR led to the drop of metal partitioning and increase of slag liquidus temperature. High pSO2 led to high deportment of Bi and Pb in the gas phase mainly in the form of sulfides, suggesting that a low pSO2 was conducive for reducing the dust ratio.

Oxygen pressure acid leaching of Gacun complex Cu concentrates

The treatment of the Gacun complex Cu concentrate with high contents of Pb,Zn,Ag,etc by oxygen pressure acid leaching was studied.It is unusual that tetrahedrite,whose treatment was rarely studied,is the primary copper mineral of the concentrates.Most of silver also occurs in the mineral.The optimum operating parameters of oxygen pressure acid leaching were established by conditional tests.Pilot scale test was carried out under the parameters,and the leaching rates of copper and zinc are as high as 97.10% and 89.83% while lead and silver are transformed into sulfate and sulfide respectively and stay in leaching residue.The copper and zinc in lixivium were reclaimed by extraction-electrowinning and purification-electrowinning,respectively,and the lead and silver in the residue were reclaimed separately by chloride leaching and thiourea leaching.The extraction rate of copper achieves 96%,and the leaching rates of lead and silver reach 90% and 95%,respectively.

Study on copper complexing ligand concentrations in several China's coastal waters

Copper complexing ligand concentrations in the Daya Bay, Qingdao coast, Jiaozhou Bay, South China Sea and Huanghe Estuary waters were determined by the anodic stripping voltammetry technique. The distribution regularity and the relationship with other parameters were discussed. The results were as follows： Copper complexing ligand concentrations of the South China Sea were a little higher than those of other sea areas, and they were apparently higher than those of the ocean. Compared with the subsurface layer （SSL） in the sea surface microlayer copper complexing ligand concentrations showed an enrichment phenomenon, of which the mechanism is similar to dissolved organic matter. The metal complexing ligand concentration profiles of the South China Sea showed that the value in the sea surface was the highest, then it decreased with depth accruing, and a higher value appeared at the bottom. Copper complex- ing ligand concentrations were higher than those of cadmium and lead. Ligands in each sea area exhibited a complicated property. In short, the distribution regularity of copper complexing ligand concentrations in China＇s coastal waters was consistent with that of other regions in the world. Meanwhile, the positive relationship between the copper complexing ligand concentrations and biological oxygen demand, chemical oxygen demand, dissolved organic carbon, and viscosity were found clearly.

Determination of copper complexation in surface microlayer of Daya Bay and Jiaozhou Bay

Copper complexing ligands concentration (C C) and conditional stability constant of the sea surface microlayer (SML) and subsurface layer (SSL) samples, collected from Daya Bay of Guangdong Province and Jiaozhou Bay of Shandong Province, were determined by anodic stripping voltammetry (ASV) technique. C C of Daya Bay in the SML ranged from 6.19×10-7 to 3.52×10-7 mol/L. C C of Jiaozhou Bay in the SML ranged from 5.30×10-7 to 3.03×10-7 mol/L in August 1998 and from 3.46×10-7 to 1.36×10-7 mol/L in May 2000. The C C concentrations were higher in all surface microlayer samples, compared with corresponding subsurface samples. The average enrichment factors of copper complexation in the SML observed above were 1.58, 1.41 and 1.56, respectively. The enrichment of C C concentration in the microlayer demonstrated that organic ligands had certain buffer action on the toxicity of the enriched trace metals in the same layer. Conditional stability constants of the SML in Jiaozhou Bay were lower than those of the SSL; however, it showed just opposite for Daya Bay. BOD (biological oxygen demand) and COD (chemical oxygen demand) indicated the organic matter content, also showed enriched in the SML. C C had an obvious relationship with BOD or COD.

Solar Photochemical Pre-Treatment for Sulphurous Ground Water Purification Process

The sulfurous water deposit exploitation in volcanic, swamp, or wetland regions, represents an alternative option for potable water supply in cities and communities around the world. However, before its consumption, it must be treated by the application of physicochemical or biological methods with the ability to separate high contents in sulfates, hydrogen sulphite and sulphides which have laxative, allergic and toxic properties in humans. Conventional methods require the supply of chemical compounds or the adequate control of different parameters such as pH, temperature, etc., and the constant maintenance within their reactors. For these reasons, the systems could have elevated operating costs and require additional steps to enable the treatment of its separated products and the final disposal of its residual waste generated. In this research, compound parabolic collectors are implemented for the use of solar energy radiation, UV-B type, in Solar Advanced Oxidation Processes in H2O2/O3/UVsolar homogeneous phase. Its application during the pre-treatment of four sulfur water wells from the region of Puebla, Mexico, demonstrated its ability to transform their sulfur compounds in sulfates of easy removal by a later stage of reverse osmosis, in an approximately 15 min treatment time process.

On correction of model of stabilization of distribution of concentration of radiation defects in a multilayer structure with account experiment data

We introduce a model of redistribution of point radiation defects, their interaction between themselves and redistribution of their simplest complexes（divacancies and diinterstitials） in a multilayer structure. The model gives a possibility to describe qualitatively nonmonotonicity of distributions of concentrations of radiation defects on interfaces between layers of the multilayer structure. The nonmonotonicity was recently found experimentally.To take into account the nonmonotonicity we modify recently used in literature model for analysis of distribution of concentration of radiation defects. To analyze the model we used an approach of solution of boundary problems,which could be used without crosslinking of solutions on interfaces between layers of the considered multilayer structures.