scholarly journals Electro-hydrometallurgical chloride process for selective gold recovery from refractory telluride gold ores: A mini-pilot study

2022 ◽  
Vol 429 ◽  
pp. 132283
Author(s):  
Ivan Korolev ◽  
Pelin Altinkaya ◽  
Mika Haapalainen ◽  
Eero Kolehmainen ◽  
Kirsi Yliniemi ◽  
...  
Keyword(s):  
Pilot Study ◽  
Gold Recovery ◽  
Gold Ores ◽  
Chloride Process

scholarly journals Bio-Oxidation of a Double Refractory Gold Ore and Investigation of Preg-Robbing of Gold from Thiourea Solution

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1216
Author(s):  
Rui Xu ◽  
Qian Li ◽  
Feiyu Meng ◽  
Yongbin Yang ◽  
Bin Xu ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Active Sites ◽  
Gold Recovery ◽  
Ftir Analysis ◽  
Gold Extraction ◽  
Gold Ores ◽  
Gold Ore ◽  
Thiourea Solution ◽  
Refractory Gold ◽  
Pure Cultures

Carbonaceous sulfidic gold ores are commonly double refractory and thus require pretreatment before gold extraction. In this paper, the capacity of pre-bio-oxidation can simultaneously decompose sulfides or deactivate carbonaceous matters (CM) from a double refractory gold ore (DRGO) using pure cultures of A. ferrooxidans or L. ferrooxidans, and a mixed culture containing A. ferrooxidans and L. ferrooxidans was investigated. The results showed that direct thiourea leaching of the as-received DRGO yielded only 28.7% gold extraction, which was due to the encapsulation of sulfides on gold and the gold adsorption of CM. After bio-oxidation, thiourea leaching of the DRGO resulted in gold extraction of over 75–80%. Moreover, bio-oxidation can effectively reduce the adsorption of carbon to gold. XRD, SEM-EDS and FTIR analysis showed that many oxygen-containing groups were introduced on the surface of DRGO during bio-oxidation, while the C=C bond was cleaved and the O–C–O and C–N bonds were degraded, causing a decrease in active sites for gold adsorption. Moreover, passivation materials such as jarosite were formed on the surface of DRGO, which might reduce the affinity of CM for gold in solutions. In addition, the cleavage of the S–S band indicated that sulfides were oxidized by bacteria. This work allows us to explain the applicability of pre-bio-oxidation for degrading both sulfides and CM and increasing gold recovery from DRGO in the thiourea system.

Pretreatment of Refractory Gold Ores Using Cell-Free Extracts of P. chrysosporium: A Preliminary Study

2013 ◽  
Vol 825 ◽  
pp. 427-430 ◽  
Author(s):  
Grace Ofori-Sarpong ◽  
Kwadwo Osseo-Asare ◽  
Ming Tien
Keyword(s):  
Gold Recovery ◽  
Active Components ◽  
Gold Extraction ◽  
Promising Alternative ◽  
Gold Ores ◽  
Refractory Gold Ores ◽  
In Vitro Processing ◽  
Refractory Gold

The fungus Phanerochaete chrysosporium has been proven to biotransform refractory gold ores, leading to increase in gold recovery. This transformation has been attributed to enzymes secreted by the microbe. This paper reports the findings of preliminary investigations aimed at assessing the use of hydrogen peroxide and cell-free extracts from the fungus, P. chrysosporium, to effect biotransformation of sulphidic refractory gold ores. The investigations show that the total dissolved arsenic, iron and sulphur in solution were up to 5.2 wt%, 0.9 wt% and 6.0 wt% respectively from flotation concentrate after 72 hrs of treatment. Analysis for sulphide sulphur in the residual solids of the gold concentrate indicated about 25 wt% oxidation within 24 hours of treatment. In general, cell-free decomposition of the samples did not increase beyond 24 hours of contact time, possibly due to exhaustion of the active components. Gold extraction by cyanidation increased by 24% after 24-hr treatment with the cell-free extracts. Comparatively, cell-free (in vitro) treatment recorded 66% overall gold recovery as against 61% for whole cell (in vivo) after 72 hours of treatment. These initial results indicate clearly that in vitro processing is a promising alternative to in vivo processing of refractory gold ores using P. chrysosporium.

Biogenic Hydrogen Sulfide for Cyanide Regeneration in Solutions during Cupriferous Gold Ores Processing

2017 ◽  
Vol 262 ◽  
pp. 131-134
Author(s):  
Anna A. Faiberg ◽  
Aleksandra N. Mikhailova ◽  
Vladimir E. Dementiev ◽  
Sergey S. Gudkov
Keyword(s):  
Hydrogen Sulfide ◽  
Sodium Cyanide ◽  
Gold Recovery ◽  
Copper Recovery ◽  
Thermophilic Microorganisms ◽  
Copper Cyanide ◽  
Gold Ores ◽  
Hydrometallurgical Processing ◽  
Optimal Approach ◽  
Process Solutions

An optimal approach to the problem of cupriferous gold ores hydrometallurgical processing is the recycling of process solutions after copper recovery and regeneration of cyanide bound in complexes. The study focuses on the copper-cyanide solutions processing technology using biogenic hydrogen sulfide for copper recovery in the form of сhalcocite, and cyanide regeneration. The strains of anaerobic sulfidogenic thermophilic microorganisms Desulfurella acetivorans and Desulfurella Kamchatkensis were used for producing hydrogen sulfide. The studies on copper precipitation and cyanide regeneration were conducted on copper-cyanide process solutions which were obtained during cyanidation of refractory cupriferous gold-bearing flotation concentrates from one of the deposits in the South Ural (Russia). Ten cycles of "Cyanidation-Regeneration" were carried out in total. The copper recovery was 86–96 %; the cyanide regeneration obtained 96 %. On an average 8.9 kg of sodium cyanide and 4.6 kg of copper sulfide were recovered from 1 m3 of solution. The sodium cyanide consumption decreased from 25.0 kg/t to 6.0 kg/t without reducing gold recovery during the CIL (carbon-in-leach) recycling process. The gold recovery was the same 63–68 %.

scholarly journals Significance of Acid Washing after Biooxidation of Sulfides in Sequential Biotreatment of Double Refractory Gold Ore from the Syama Mine, Mali

Minerals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1316
Author(s):  
Cindy Cindy ◽  
Ryotaro Sakai ◽  
Diego M. Mendoza ◽  
Kojo T. Konadu ◽  
Keiko Sasaki
Keyword(s):  
Gold Recovery ◽  
Carbonaceous Matter ◽  
Acid Attack ◽  
Gold Ores ◽  
Gold Ore ◽  
Positive Effects ◽  
Acid Washing ◽  
Washing Process ◽  
Refractory Gold ◽  
Mineralogical Compositions

Environmentally friendly pretreatment of double refractory gold ores (DRGO) to improve gold recovery without emitting pollutant gas is challenging. Sequential biotreatment, including iron-oxidizing microorganisms to decompose sulfides, followed by the enzymatic decomposition of carbonaceous matter, was recently developed. The effect of acid washing by 1 M HCl for 24 h between two bioprocesses was evaluated using a real double refractory gold ore from the Syama mines, Mali, which includes 24 g/t of Au and 5.27 wt % of carbon with a relatively higher graphitic degree. The addition of the acid washing process significantly improved gold recovery by cyanidation to yield to 84.9 ± 0.7% from 64.4 ± 9.2% (n = 2). The positive effects of acid washing can be explained by chemical alteration of carbonaceous matter to facilitate the accessibility for lignin peroxidase (LiP) and manganese peroxidase (MnP) in cell-free spent medium (CFSM), although the agglomeration was enhanced by an acid attack to structural Fe(III) in clay minerals. Sequential treatment of DRGO basically consists of the oxidative dissolution of sulfides and the degradation of carbonaceous matter prior to the extraction of gold; however, the details should be modified depending on the elemental and mineralogical compositions and the graphitic degree of carbonaceous matter.

scholarly journals THE GOLD RECOVERY CLEAN TECHNOLOGY FROM REFRACTORY GOLD ORES USING MICROWAVES’ ENERGY

2018 ◽  
Author(s):  
Nicolae Tomus ◽  
◽  
Marius Zlagnean ◽  
Ioana-Carmen Popescu (Hostuc)
Keyword(s):  
Clean Technology ◽  
Gold Recovery ◽  
Gold Ores ◽  
Refractory Gold Ores ◽  
Refractory Gold

Pilot study on criteria in cavity preparation-facts or artifacts?

1973 ◽  
Vol 37 (11) ◽  
pp. 27-31 ◽  
Author(s):  
G Salvendy ◽  
WM Hinton ◽  
GW Ferguson ◽  
PR Cunningham
Keyword(s):  
Pilot Study ◽  
Cavity Preparation

A Pilot Study of Early Storybook Reading With Babies With Hearing Loss

2019 ◽  
Vol 62 (9) ◽  
pp. 3397-3412
Author(s):  
Michelle I. Brown ◽  
David Trembath ◽  
Marleen F. Westerveld ◽  
Gail T. Gillon
Keyword(s):  
Hearing Loss ◽  
Pilot Study ◽  
Visual Analysis ◽  
Single Case ◽  
Eye Contact ◽  
Preliminary Evidence ◽  
Storybook Reading ◽  
Book Selection ◽  
Turn Taking ◽  
Parent Child

Purpose This pilot study explored the effectiveness of an early storybook reading (ESR) intervention for parents with babies with hearing loss (HL) for improving (a) parents' book selection skills, (b) parent–child eye contact, and (c) parent–child turn-taking. Advancing research into ESR, this study examined whether the benefits from an ESR intervention reported for babies without HL were also observed in babies with HL. Method Four mother–baby dyads participated in a multiple baseline single-case experimental design across behaviors. Treatment effects for parents' book selection skills, parent–child eye contact, and parent–child turn-taking were examined using visual analysis and Tau-U analysis. Results Statistically significant increases, with large to very large effect sizes, were observed for all 4 participants for parent–child eye contact and parent–child turn-taking. Limited improvements with ceiling effects were observed for parents' book selection skills. Conclusion The findings provide preliminary evidence for the effectiveness of an ESR intervention for babies with HL for promoting parent–child interactions through eye contact and turn-taking.

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