查看更多>>摘要：Currently, there is a lack of research on column bio-oxidation for low-grade refractory gold ore with high arsenic and sulfur content. Therefore, it is essential and significative to investigate column bio-oxidation for this type of gold ore. The column bio-oxidation process of refractory gold ore was characterized by a variety of analytical methods, including X-ray diffraction, 16S rRNA gene analysis, scanning electron microscope coupled with energy-dispersive X-ray spectroscopy and 3D confocal laser scanning microscopy. The evolution of the microbial community structure was analyzed. Simultaneously, the process of passive film formation and the behavior of the dynamic corrosion on the sulfide surfaces were described in detail. The results showed that the cyanidation of gold yielded 81 +/- 2% after column bio-oxidation. The oxidation extent for As, Fe and S were 57 +/- 1%, 38 +/- 1% and 44 +/- 1%, respectively. The community structure of attached and planktonic microorganisms was different and changed with the oxidation time. Importantly, the Sulfur film was observed on the arsenopyrite surface under scanning electron microscope, yet it was not found on the pyrite surface. This finding revealed that the inhibitory effect generated by the passive film of arsenopyrite was significantly higher than that of pyrite. Furthermore, the average corrosion pit volume per unit area of pyrite and arsenopyrite were 161 +/- 6 mu m(3)/mu m(2) and 65 +/- 3 mu m(3)/mu m(2). This indicated that arsenopyrite was more easily oxidized during the column bio-oxidation.
Bergamo, Pedro A. de S.Streng, Emilia S.Carvalho, Marly A. deRosenkranz, Jan...
6页
查看更多>>摘要：There is a lack of skilled operators for mineral processing plants in the mining sector, which might be related to the challenge of creating trainings that addresses the operator's daily work problems. In recent years, the use of simulator-based trainings as a tool to build competence has grown in many different fields. With the help of technologies like virtual reality, these tools have been demonstrated to increase awareness and the capability of workers when compared to traditional learning methods. In this paper, a review is presented on the development and application of such technologies in simulation-based training for the training of operators of the minerals industry in the last 20 years. Proposed next steps and new technologies with the potential of improving these applications are also discussed.
查看更多>>摘要：Previous studies on oleic acid systems have shown that calcium dioleate formed during the flotation process plays an important role. Calcium dioleate has been extensively studied as an important intermediate product in sodium oleate flotation of calcium-containing minerals sodium oleate, but its use as a collector to separate calciumcontaining minerals remains unverified. The effect of calcium dioleate on fluorite, calcite and scheelite flotation and the adsorption mechanism on the mineral surface were examined using solution chemical analysis, flotation test, adsorption measurement, atomic force microscopy (AFM) and transmission electron microscopy (TEM) in this study. Solution chemical calculations prove that stable calcium dioleate colloid will be the dominant species at certain pH, calcium ion and oleate concentrations. Flotation experiments showed that the calcium dioleate plays an important role in the flotation process using sodium oleate. Calcium dioleate has better flotation effect for fluorite and scheelite but weaker effect for calcite than sodium oleate. Adsorption measurement showed that calcium dioleate is more easily adsorbed on the surface of scheelite and fluorite. AFM and TEM measurements exhibited that the formation of micelle adsorption on the surface of scheelite and fluorite caused by calcium dioleate clearly affects the surface roughness. Calcium dioleate colloids can likely enhance the surface roughness of scheelite and fluorite via selectively adsorption to improve the flotation of scheelite and fluorite.
查看更多>>摘要：Phosphate concentrates are widely used as primary sources in the production of fertilizers worldwide, but the efficient removal of dolomite from apatite in flotation relies heavily on selective depressants. Conventional apatite depressants such as sulfuric and phosphoric acid inevitably cause serious environmental pollution. It is urgent to explore green and efficient depressants to substitute conventional ones for the clean production of phosphate concentrate. In this work, iminodisuccinic acid (IDS) was explored as an efficient and environmentalfriendly dolomite depressant in the direct flotation of apatite from dolomite. The depression performances were evaluated by micro-flotation and the interaction mechanism was revealed through adsorption capacity, Microcalorimetry, Zeta potential, Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) measurements. Mico-flotation results showed that IDS selectively depressed dolomite but hardly affected apatite flotation, improving the separation efficiency and upgrading the quality of apatite concentrates successfully. Mechanism study demonstrated that IDS preferentially adsorbed on dolomite due to its higher affinity to Mg sites on dolomite. IDS was dominantly chelated with Mg sites to form octahedral complexing structure via the coordination of COO- with Mg sites. While IDS was weakly adsorbed on apatite thought weak hydrogen bond between F sits of apatite with carboxyl within IDS. The preadsorption of IDS impeded NaOL adsorption on dolomite, but didn't influence the NaOL adsorption on apatite. The work proved that IDS could be used as a green and selective dolomite depressant for the clean flotation of apatite from dolomite, which is of great importance for the sustainable production of fertilizer.
查看更多>>摘要：Leaching recovery of rare earth elements (REEs) from two natural kaolinite samples were investigated in this study. Using standard leach conditions without pretreatment, only 10% and 56% of the total REEs were leached from the raw samples, respectively. However, pretreatment by calcination at temperatures between 500 degrees C and 900 degrees C increased the leaching recovery of total REEs to values as high as 93% for both samples. Mineralogical characterization and acid leaching results suggested that the decomposition of the kaolinite structure occurs as a function of calcination temperature. Comparisons between the REEs and the major constituent elements of kaolinite showed that their leaching characteristics contrasted. Moreover, sequential chemical extraction results suggested that the fractions of REEs occurring in an ion-adsorption form were negligible. Therefore, the REEs were primarily associated with REE-bearing minerals of which, a portion was encapsulated in kaolinite aggre-gates while the remaining existed as liberated particles. These association characteristics were proven through SEM-EDX analysis. Based on the mineralogy characterization, acid leaching, and sequential chemical extraction results, it was concluded that the REEs have complicated modes of occurrence and association characteristics with kaolinite. The positive impacts of calcination on the leaching recovery of REEs are likely due to two mechanisms, i.e., (1) liberation of the encapsulated REE-bearing minerals through expansion of the kaolinite aggregates, and (2) conversion of the REE-bearing minerals into more soluble forms.
Ans, MuhammadMakhdoom, Muhammad AtifIrfan, Muhammad FaisalAl Abir, Anzum...
10页
查看更多>>摘要：With the increasing applications of nickel in industrial homogeneous catalysis, coatings, and batteries a large amount can be recycled from waste orthodontic implants that contain -10% nickel. This research has reported a cost-effective, low temperature, and environmentally friendly route for recovering nickel from the waste orthodontic implants using a hydrometallurgical technique. Response surface methodology coupled with central composition design (CCD) was employed to optimize and maximize the yield. Leaching time, temperature, rotational speed, and solid-liquid (S-L) ratio were considered independent parameters, while recovery of nickel was taken as a response. A quadratic regression model was developed for the maximization of nickel leaching concerning input parameters and response. Different performance indicators (i.e., RE, RMSE, and MAE) were employed to assess the developed model further. Based on ANOVA analysis, temperature, and S-L ratio were found to be statistically significant factors. The results show a maximum nickel yield of similar to 95% was achieved with optimized parameters viz., temperature (90 degrees C), leaching time (180 min), rotational speed (40 rpm), and S-L ratio (1:50). Furthermore, the kinetic analysis of the process is also carried out using the Jander rate equation, and the calculated activation energy of nickel leaching with a first-order reaction is 39.8 kJ/mol.
查看更多>>摘要：One of the challenging tasks in tailings management is dealing with clay-based minerals, which create constant problems, especially in pumping thickened slurries. For their treatment, a broad range of additives has been tested in situ, where sodium triphosphate has shown some successful preliminary advantages due to its ability to disperse particles. This work aims to evaluate the adsorption capacity of sodium triphosphate in kaolinite from a theoretical molecular approach that combines quantum calculations and molecular dynamics simulation. First, triphosphate was parameterized from quantum calculations (QM) to obtain the force field that describes the system using molecular dynamics (MD) simulation. Then, MD simulations described the behavior of triphosphate in saline solutions. The results indicated that triphosphate can self-aggregate and even more in the presence of NaCl salts. The adsorption of triphosphate on kaolinite surfaces was stable and formed mainly sodium-mediated bridge-type interactions between the charged groups. The adsorption was favorable when the triphosphate concentration increased, but in the presence of NaCl, it increased only up to concentrations of 0.06 M. These latter results can be attributed to the tendency to form aggregate over the interaction with kaolinite.
Vakylabad, Ali BehradNazari, SaberehDarezereshki, Esmaeel
10页
查看更多>>摘要：The formation of hydrolyzed ferric iron (Fe (III)) as jarosite could limit the bioleaching of copper and significantly lower the dissolution rate of low-grade chalcopyrite ore. Thus, to improve the rate through overcoming the hindered dissolution of chalcopyrite, this study investigated the influence of chloride addition into leaching lixiviant. As a microbial source, mixed mesophiles, moderately thermophilic, and thermophilic microorganisms were adapted to about 120 mM NaCl solution. After optimization of the ore bioleaching in 64 controlled minicolumns, the scaled tests in 2-m tall columns were conducted to study the overall leaching procedure and precipitation of the jarosite. Under normal aeration conditions (0.05 Nm3/m2/h) with hybrid irrigation (120 mM NaCl in H2SO4 solution at pH = 1.5), copper recovery reached 80% after 120 days while it was approximately 50% with limited one (0.003 Nm3/m2/h). The limited aeration column had a moderate oxidation-reduction potential (ORP) with values < 450 mV. This significant improvement in dissolution is explained by the reduced precipitation of passivating layer (mainly jarosite). These conclusions were also confirmed by the estimation of pyrite and natrojarosite with a modified ASTM D-2492 (MASTM D-2492). Moreover, to identify the microbial communities in the columns, DNA extraction and 16Sr RNA gene PCR amplification and sequencing were done.
查看更多>>摘要：Uncovered mine tailings may result in environmental stresses such as severe acidification and heavy metal discharge to adjacent watercourses. These problems originate in metal sulfide oxidation, which results in acidic metal-rich leachate, known as acid mine drainage (AMD) that persists over time. Sulfides in mine tailings can persist for centuries. Thus, accelerating the sulfur oxidation process can help mitigate this problem. In this study, the use of ozone and hydrogen peroxide to increase the leaching of coal mine tailings was investigated in detail. One of the biggest challenges when using oxidizers is determining the acting plume. To this end, the decomposition kinetics of oxidants were studied when contacting mine tailings. Additionally, a mathematical model was developed to predict the subsurface propagation of the oxidizers used. In the group where ozone was applied, there was a 62% reduction in sulfur content, while the corresponding reduction in the control group was only 18%. The results indicated that ozone and hydrogen peroxide increased metal leaching, and decreased ecotoxicity compared to a control group. The kinetic rates were dependent on the saturation of coal mine tailings. Furthermore, the spread model contributed to oxidation plume determination. For ozone, it was observed that for a kinetic rate of -0.2669.C-O3(0.7899) mol.m(-3).s(-1), a 60% increase in pressure causes the ozone plume to increase the effective transport distance by 30%. This paper presents an innovative strategy for mitigating AMD.
查看更多>>摘要：The effect and mechanism of visible light and Ag+ on chalcopyrite bioleaching were investigated in the presence of Acidithiobacillus ferrooxidans. The results of bioleaching tests revealed that the copper extraction was improved significantly when visible light and Ag+ were simultaneously present. By analyzing bioleaching parameters, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical imped-ance spectroscopy results: the accumulation of jarosite and the formation of covellite-like species led to the slow dissolution rate of chalcopyrite at the end period of bioleaching. The introduction of Ag+ resulted in the formation of Ag2S and Ag-0 on the surface of chalcopyrite. And light illumination promoted the accumulation of Ag2S and Ag-0 on chalcopyrite surface, thus reducing the resistance of the passivation layer. Further, light illumination increased the rate of charge transfer and promoted the dissolution of chalcopyrite.
NSTL
Elsevier