scholarly journals Dissolution of Black Copper Oxides from a Leaching Residue

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1012
Author(s):  
Víctor Quezada ◽  
Oscar Benavente ◽  
Cristopher Beltrán ◽  
Danny Díaz ◽  
Evelyn Melo ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Acid Leaching ◽  
Atomic Emission ◽  
Copper Oxides ◽  
Leach Residue ◽  
Copper Extraction ◽  
Original Sample ◽  
Hydrogen Electrode ◽  
Inductively Coupled ◽  
Leaching Residue

This article presents the behavior of black copper minerals in reducing acid leaching using FeSO4 as reducing agent. The original sample, which was a blend of green and black copper minerals, was treated first by an oxidizing acid leach using O3 to dissolve the soluble phase (green copper oxides). The residue (mainly black copper) was evaluated by agitated leaching under three different solution potentials, with respect to the standard hydrogen electrode (SHE) (450, 500, and 600 mV (SHE)) at 25 °C. The original sample and the leach residue were characterized by scanning electron microscope (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The O3 leach residue was 1.43% copper, with 50% of the insoluble phase associated with copper pitch, copper limonites, and unreacted chrysocolla. The results of leaching using FeSO4 demonstrate that it is possible to obtain 90% copper extraction using a solution with a potential of 450 mV, while leaching at 600 mV resulted in 65% copper extraction. Acid consumption was 40 kg/t in the test at 450 mV, followed by 30 kg/t in the 500 mV test, and finally 25 kg/t in the 600 mV test, showing that reactivity decreases with increased solution potential. The results show that retreatment of a leaching residue is possible, considering the presence of copper pitch, copper limonites, and chrysocolla as the main copper contributing minerals. Modeling of copper extraction with nonlinear regression is proposed. The retreatment of residues resulting from conventional acid leaching can be an alternative to make use of the treatment capacity of hydrometallurgical plants.

Effect of Mechanical Activation on Leachability of Fayalite in Sulfuric Acid Solution

2020 ◽  
Vol 10 (2) ◽  
pp. 82-87
Author(s):  
Rashid Nadirov ◽  
Lyazzat Mussapyrova
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Mechanical Activation ◽  
Ferrous Metallurgy ◽  
Sulfuric Acid Solution ◽  
Inductively Coupled Plasma ◽  
Acid Leaching ◽  
Atomic Emission ◽  
Copper Smelter ◽  
Inductively Coupled

Background: Being by-products of non-ferrous metallurgy, slags contain fayalite (Fe2SiO4) as the major component. Since hydrometallurgical methods are considered as the most promising for processing such material to obtain valuable metals, increasing the leachability of fayalite in sulfuric acid as a widely used leaching agent is an important task. Objective : The present work was devoted to increasing the reactivity of fayalite by using mechanical activation. Methods: Fayalite, synthesized with the use of powders of metallic Fe, Fe2O3, and SiO2, was subjected to mechanical activation in the planetary ball mill at 400 rpm with a ball/powder ratio of 5 for 45 minutes. Then, activated and non-activated fayalite samples were subjected to sulfuric acid leaching. Before leaching, solid samples were characterized by XRD and Dynamic Light Scattering (DLS). Quantitative analysis of Fe and Si in the leachate was determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy. Results: Mechanical activation led to partial amorphization of the initial fayalite sample. It was found that the leaching rate constants of the treated samples in sulfuric acid solution (50-80 g×L-1) at 298, 338, and 368 K increased and the activation energy of the leaching process decreased, i.e. mechanical activation enhances the reactivity of fayalite in H2SO4 solution. Conclusion: Mechanical activation can be applied to improve fayalite leachability in sulfuric acid solution. The results obtained can be used in the development of methods for leaching slag of non-ferrous metallurgy, in particular, copper smelter slags, the major component of which is fayalite.

scholarly journals Mineralogical Characterization and Acid Pretreatment of a Gold Calcine Leach Residue

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Godfrey Tinashe Bare ◽  
Jean Jacques Kalombo Mbayo ◽  
Sehliselo Ndlovu ◽  
Alan Shemi ◽  
Liberty Chipise
Keyword(s):  
Inductively Coupled Plasma ◽  
Acid Leaching ◽  
Leach Residue ◽  
X Ray Diffraction ◽  
Acid Pretreatment ◽  
Mineralogical Characterization ◽  
Inductively Coupled ◽  
Left Behind ◽  
Process Route ◽  
Ultrafine Milling

Miners around Zimbabwe used to supply gold concentrates from sulphide flotation to the Kwekwe Roasting Plant (Zimbabwe) for toll treatment. The concentrates were roasted in Edward’s roasters and the calcine product was leached by cyanidation. Due to inefficient roasting, overall gold recoveries of 75–80% left behind a rich calcine leach residue at the Kwekwe Roasting Plant. The characterization performed to establish a potential process route involved several techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), fire assaying and inductively coupled plasma (ICP). Assays conducted on samples from the 350,000 tons tailings dam residue, created over the operational years, gave an average Au grade of 8.58 g/t and 12.54 g/t for Ag. The base metals assayed—0.11% Cu, 0.10% Pb, 0.17% Zn and 26.05% Fe. SiO2 (36.1%), Fe2O3 (36.9%), Mg3Si4O10 (OH)2 (8.9%), NaAlSi3O8 (6.9%), and Fe3O4 (6.4%)—were the major mineral phases in the cyanide leach residue. SEM gold scans on 24 polished sections showed only 2 discrete gold particles of less than 5 µm, with one partially liberated and associated with quartz, while the other was fully liberated. Therefore, the particulate gold in the calcine leach residue was negligible. It was deduced from the analysis after ultrafine milling (P80 < 5 µm) followed by cyanidation that 68.53% of the gold was sub-microscopic. Direct cyanidation using bottle roll resulted in only 2.33% of the total gold being leachable, indicating that the calcine leach residue was highly refractory. Diagnostic leaching by sequential use of acids in order of their strength resulted in HCl leachable phases (CaCO3, CaMg(CO3)2, PbS, Fe1-XS, and Fe2O3) freeing 4.2% of the total Au during subsequent cyanidation leach. H2SO4 leachable phases (Cu–Zn sulphides, labile FeS2) released an additional 26.57% during cyanidation, whereas HNO3 leachable phases (FeS2, FeAsS) released a further 20.98% of Au. After acid treatment and subsequent cyanidation, hot caustic leach of the residue followed by carbon in pulp resulted 4.43% of the total gold being eluted. Therefore, 4.43% of the total gold was surface bound. From the analysis after diagnostic acid leaching, it was deduced that a total of 54.08% of the gold was in the acid-leachable phase. Due to cost and environmental considerations, H2SO4 was selected for the evaluation of acid digestion as a pretreatment stage followed by cyanidation. Increasing the H2SO4 strength for the pretreatment of the calcine leach residue increased gold recoveries during cyanidation.

Rapid Catalyst Capture Enables Metal-Free Parahydrogen-Based Hyperpolarized Contrast Agents

2018 ◽  
Author(s):  
Danila Barskiy ◽  
Lucia Ke ◽  
Xingyang Li ◽  
Vincent Stevenson ◽  
Nevin Widarman ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Contrast Agents ◽  
Inductively Coupled Plasma ◽  
Organometallic Compounds ◽  
Atomic Emission ◽  
Platinum Group Metals ◽  
Resonance Spectroscopy ◽  
Plasma Atomic Emission ◽  
Inductively Coupled

<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>

Rapid Catalyst Capture Enables Metal-Free Parahydrogen-Based Hyperpolarized Contrast Agents

2018 ◽  
Author(s):  
Danila Barskiy ◽  
Lucia Ke ◽  
Xingyang Li ◽  
Vincent Stevenson ◽  
Nevin Widarman ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Contrast Agents ◽  
Inductively Coupled Plasma ◽  
Organometallic Compounds ◽  
Atomic Emission ◽  
Platinum Group Metals ◽  
Resonance Spectroscopy ◽  
Plasma Atomic Emission ◽  
Inductively Coupled

<p>Hyperpolarization techniques based on the use of parahydrogen provide orders of magnitude signal enhancement for magnetic resonance spectroscopy and imaging. The main drawback limiting widespread applicability of parahydrogen-based techniques in biomedicine is the presence of organometallic compounds (the polarization transfer catalysts) in solution with hyperpolarized contrast agents. These catalysts are typically complexes of platinum-group metals and their administration in vivo should be avoided.</p> <p><br></p><p>Herein, we show how extraction of a hyperpolarized compound from an organic phase to an aqueous phase combined with a rapid (less than 10 seconds) Ir-based catalyst capture by metal scavenging agents can produce pure parahydrogen-based hyperpolarized contrast agents as demonstrated by high-resolution nuclear magnetic resonance (NMR) spectroscopy and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The presented methodology enables fast and efficient means of producing pure hyperpolarized aqueous solutions for biomedical and other uses.</p>

Silicate analysis of carbonated rocks using ICP-AES with calibration by the concentration ratio

2020 ◽  
Vol 86 (5) ◽  
pp. 16-21
Author(s):  
T. A. Karimova ◽  
G. L. Buchbinder ◽  
S. V. Kachin
Keyword(s):  
Inductively Coupled Plasma ◽  
Concentration Ratio ◽  
Total Error ◽  
Atomic Emission ◽  
Emission Spectrometry ◽  
Calibration Error ◽  
Plasma Atomic Emission Spectrometry ◽  
Standard Samples ◽  
Inductively Coupled ◽  
Carbonate Materials

Calibration by the concentration ratio provides better metrological characteristics compared to other calibration modes when using the inductively coupled plasma atomic emission spectrometry (ICP-AES) for analysis of geological samples and technical materials on their base. The main reasons for the observed improvement are: i) elimination of the calibration error of measuring vessels and the error of weighing samples of the analyzed materials from the total error of the analysis; ii) high intensity of the lines of base element; and iii) higher accuracy of measuring the ratio of intensities compared to that of measuring the absolute intensities. Calcium oxide is better suited as a base when using calibration by the concentration ratio in analysis of carbonate rocks, technical materials, slags containing less than 20% SiO2 and more than 20% CaO. An equation is derived to calculate the content of components determined in carbonate materials when using calibration by the concentration ratio. A method of ICP-AES with calibration by the concentration ratio is developed for determination of CaO (in the range of contents 20 – 100%), SiO2 (2.0 – 35%), Al2O3 (0.1 – 30%), MgO (0.1 – 20%), Fe2O3 (0.5 – 40%), Na2O (0.1 – 15%), K2O (0.1 – 5%), P2O5 (0.001 – 2%), MnO (0.01 – 2%), TiO2 (0.01 – 2.0%) in various carbonate materials. Acid decomposition of the samples in closed vessels heated in a HotBlock 200 system is proposed. Correctness of the procedure is confirmed in analysis of standard samples of rocks. The developed procedure was used during the interlaboratory analysis of the standard sample of slag SH17 produced by ZAO ISO (Yekaterinburg, Russia).

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