leach residue
Recently Published Documents


TOTAL DOCUMENTS

52
(FIVE YEARS 12)

H-INDEX

9
(FIVE YEARS 2)

Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 10
Author(s):  
Godfrey Tinashe Bare ◽  
Jean Jacques Kalombo Mbayo ◽  
Sehliselo Ndlovu ◽  
Alan Shemi ◽  
Liberty Chipise

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.


2020 ◽  
Vol 156 ◽  
pp. 106489
Author(s):  
Desmond Attah-Kyei ◽  
Guven Akdogan ◽  
Christie Dorfling ◽  
Johan Zietsman ◽  
Daniel Lindberg ◽  
...  
Keyword(s):  

2020 ◽  
Vol 266 ◽  
pp. 121539
Author(s):  
Melina Roshanfar ◽  
Misagh Khanlarian ◽  
Fereshteh Rashchi ◽  
Babak Motesharezadeh
Keyword(s):  

Metals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1012
Author(s):  
Víctor Quezada ◽  
Oscar Benavente ◽  
Cristopher Beltrán ◽  
Danny Díaz ◽  
Evelyn Melo ◽  
...  

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.


Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 654 ◽  
Author(s):  
Päivi Kinnunen ◽  
Jarno Mäkinen ◽  
Marja Salo ◽  
Ratana Soth ◽  
Konstantinos Komnitsas

Copper slags produced in vast quantities in smelting operations could be considered as secondary material sources instead of stockpiling them in landfills. This study investigates the recovery of valuable metals from copper slag and the valorisation of the leach residue as construction material in line with the principles of a circular economy. By taking into account that the environmental characterization of the as-received copper slag did not allow its disposal in landfills without prior treatment, chemical and biological leaching were tested for the recovery of metals. Pre-treatment with acids, namely HNO3 and H2SO4, resulted in the extraction of several target metals and the production of an almost inert waste. Despite the clearly better oxidative conditions prevailing in the bioleaching reactors, chemical leaching resulted in the higher dissolution of Cu (71% vs. 51%), Co (70% vs. 36%), and Zn (65% vs. 44%). The acid consumption was much lower during the bioleaching experiments compared to the chemical leaching. The bioleach residue was suitable for its use as supplementary cementitious material, showing a better performance than the reference sample without causing any detrimental effects to the calcium aluminate cement (CAC) quality. The complete valorisation of copper slags is expected to improve the economics of the process, by avoiding landfill costs and producing saleable products with high added value.


2020 ◽  
Author(s):  
Astrid D. Toache-Pérez ◽  
Ana M. Bolarín-Miró ◽  
Félix Sánchez-De Jesús ◽  
Gretchen T. Lapidus

Abstract Rare earth elements (REE) are essential for the production of technological devices. However, their high demand and low availability, together with an increase in electronic waste generation, compel the development of efficient, economic and green methods for recovering these elements from electronic waste. In this work, a facile method for selective recovering of REE from Liquid Crystal Display (LCD) screen wastes, employing ultrasound assisted leaching is presented. The screen wastes were milled and sieved to pass through a -325 mesh sieve. The milled powder was subjected to ultrasound-assisted leaching in an aqueous medium, at room temperature (25 °C) and pH 6 for 60 minutes. Subsequently, a magnetic separation was applied to the leach residue. ICP was employed to quantitatively analyze the composition of the LCD powders and determine the effectiveness of the extraction process. SEM-EDS allowed qualitative chemical analysis of the solid materials. The results shown that the LCD screen wastes are formed, mainly, by amorphous oxides of Si, Fe, In, Sn and REE. The amount of Gadolinium (Gd) and Praseodymium (Pr) in the wastes were 93 mg kg-1 and 24 mg kg-1, respectively, which justifies their recovery. X-ray diffraction analysis of the magnetic portion of the leach residue, confirmed the presence of an amorphous phase together with crystalline metallic iron alloy. The magnetic behavior, obtained by Vibration Sample Magnetometry, helped to understand the nature of the residues. The formation of this metallic alloy is attributed to the effect of high power ultrasonic during the leach. It was confirmed that the magnetic residues concentrates and recovers 87 wt. % of Gd and 85 wt. % of Pr contained in the original material. Therefore, ultrasound-assisted leaching is a selective and facile method for recovering Gd and Pr from waste LCD.


2020 ◽  
Vol 989 ◽  
pp. 448-455
Author(s):  
Pavel Grudinsky ◽  
Ekaterina Podjelnikova ◽  
Valery Dyubanov

The paper presents the results of the investigation of zinc leach residue (ZLR) processing by sulphatizing roasting with iron sulphates FeSO4 and Fe2(SO4)3 followed by water leaching. The elemental and phase compositions of ZLR of JSC "Chelyabinsk Zinc Plant" were studied. Based on the thermodynamic calculations using HSC Chemistry 9.9 software, the temperature ranges of the sulphatizing roasting and the required amounts of iron sulphate additives for the sulphation of zinc and copper were determined. Subsequent experiments showed that recovery rates of zinc and copper reached 99.5% and 89.1% respectively, while iron remained in the leached residue. The results have indicated a high efficiency of sulphatizing roasting to transform zinc and copper contained in ZLR from ferrite to water-soluble sulphate.


2020 ◽  
Vol 148 ◽  
pp. 105797
Author(s):  
Misagh Khanlarian ◽  
Melina Roshanfar ◽  
Fereshteh Rashchi ◽  
Babak Motesharezadeh

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 365 ◽  
Author(s):  
Junhui Xiao ◽  
Yang Peng ◽  
Wei Ding ◽  
Tao Chen ◽  
Kai Zou ◽  
...  

In this study, a roasting-hydrolysis-acid leaching process is used to extract scandium from the scandium rough concentrate. The scandium rough concentrate containing Sc2O3 of 76.98 g/t was obtained by magnetic separation, gravity separation, and electric separation from Sc-bearing Vi-Ti magnetite tailings in the Panxi area of China. The majority of scandium in scandium rough concentrate mainly occurs in diopside, titanopyroxene, montmorillonite, chlorite, talc, aluminosilicate minerals, and isomorphism. Sodium salt and scandium coarse concentrate are added into the roasting furnace for roasting, which makes the fusion reaction of silicon, aluminum and sodium salt to produce soluble salts such as sodium silicate and sodium metaaluminate. Scandium is further recovered from the hydrolysis residue by acid leaching. Test results show scandium leaching recovery of 95.12% and the acid leaching residue with Sc2O3 content of 8.12 g/t are obtained, while the extraction of scandium is obvious. There is no obvious peak value of Scandium spectrum in hydrochloric acid leach residue. Most of scandium in hydrolytic residue is dissolved into Sc3+ and enters into the liquid phase. The main minerals in leach residue are perovskite, ferric silicate, and olivine.


Sign in / Sign up

Export Citation Format

Share Document