Flotation of Carbonaceous Matter from a Double Refractory Gold Ore: The Effect of MIBC on Flotation Performance and Kinetics

The use of alkaline pressure oxidation to pretreat refractory gold ore often results in insufficient gold recovery (<60%) in downstream thiosulfate leaching. To improve gold recovery, flotation was considered for the separation of carbonaceous matter (C-matter). In this study, the effect of MIBC on C-matter flotation was investigated to understand the role of the frother in bubble and froth formation and on flotation kinetics. MIBC dosages between 30 and 150 g/t were used in combination with 500 g/t of kerosene as a collector. The results showed that the recovery and selectivity of C-matter were improved with increasing MIBC dosages. Improved selectivity at higher MIBC dosages was attributed to faster C-matter recovery as bubble size decreased to the critical coalescence concentration (CCC) and to changes to the foam structure. Analysis of flotation kinetics showed that the flotation rate increased as the MIBC dosage increased due to the decreasing bubble size and the reduced induction time caused by the interaction between the collector and the frother. The results of this study explain the role of MIBC in C-matter flotation and can be used as a design basis for scavenger-cleaner flotation testing. Overall, the results show the potential for flotation as a means to improve gold recovery in thiosulfate leaching through the removal of C-matter.

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

Minerals ◽

10.3390/min11121316 ◽

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.

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Enhanced Gold Recovery from Alkaline Pressure Oxidized Refractory Gold Ore After its Mechanical Activation Followed by Thiosulfate Leaching

Journal of Sustainable Metallurgy ◽

10.1007/s40831-021-00476-7 ◽

2022 ◽

Author(s):

Sugyeong Lee ◽

Farzaneh Sadri ◽

Ahmad Ghahreman

Keyword(s):

Mechanical Activation ◽

Gold Recovery ◽

Gold Ore ◽

Refractory Gold ◽

Thiosulfate Leaching

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Modelling pyrite oxidation in a refractory gold ore stockpile to estimate the gold recovery via direct cyanide leaching – A case study

Minerals Engineering ◽

10.1016/j.mineng.2021.107177 ◽

2021 ◽

Vol 173 ◽

pp. 107177

Author(s):

Hang Wang ◽

Peter A. Dowd ◽

Chaoshui Xu

Keyword(s):

Pyrite Oxidation ◽

Gold Recovery ◽

Cyanide Leaching ◽

Gold Ore ◽

Refractory Gold

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Process simulation and gate-to-gate life cycle assessment of hydrometallurgical refractory gold concentrate processing

The International Journal of Life Cycle Assessment ◽

10.1007/s11367-019-01723-6 ◽

2019 ◽

Vol 25 (3) ◽

pp. 456-477 ◽

Cited By ~ 1

Author(s):

Heini Elomaa ◽

Pia Sinisalo ◽

Lotta Rintala ◽

Jari Aromaa ◽

Mari Lundström

Keyword(s):

Global Warming ◽

Life Cycle Assessment ◽

Life Cycle ◽

Environmental Impacts ◽

Process Simulation ◽

Development Stage ◽

Environmental Indicators ◽

Gold Recovery ◽

Pressure Oxidation ◽

Refractory Gold

Abstract Purpose Currently, almost all cyanide-free gold leaching processes are still in the development stage. Proactively investigating their environmental impacts prior to commercialization is of utmost importance. In this study, a detailed refractory gold concentrate process simulation with mass and energy balance was built for state-of-the-art technology with (i) pressure oxidation followed by cyanidation and, compared to alternative cyanide-free technology, with (ii) pressure oxidation followed by halogen leaching. Subsequently, the simulated mass balance was used as life cycle inventory data in order to evaluate the environmental impacts of the predominant cyanidation process and a cyanide-free alternative. Methods The environmental indicators for each scenario are based on the mass balance produced with HSC Sim steady-state simulation. The simulated mass balances were evaluated to identify the challenges in used technologies. The HSC Sim software is compatible with the GaBi LCA software, where LCI data from HSC-Sim is directly exported to. The simulation produces a consistent life cycle inventory (LCI). In GaBi LCA software, the environmental indicators of global warming potential (GWP), acidification potential (AP), terrestrial eutrophication potential (EP), and water depletion (Water) are estimated. Results and discussion The life cycle assessment revealed that the GWP for cyanidation was 10.1 t CO2-e/kg Au, whereas the halogen process indicated a slightly higher GWP of 12.6 t CO2-e/kg Au. The difference is partially explained by the fact that the footprint is calculated against produced units of Au; total recovery by the halogen leaching route for gold was only 87.3%, whereas the cyanidation route could extract as much as 98.5% of gold. The addition of a second gold recovery unit to extract gold also from the washing water in the halogen process increased gold recovery up to 98.5%, decreasing the GWP of the halogen process to 11.5 t CO2-e/kg Au. However, both evaluated halogen processing scenarios indicated a slightly higher global warming potential when compared to the dominating cyanidation technology. Conclusions The estimated environmental impacts predict that the development-stage cyanide-free process still has some challenges compared to cyanidation; as in the investigated scenarios, the environmental impacts were generally higher for halogen leaching. Further process improvements, for example in the form of decreased moisture in the feed for halide leaching, and the adaptation of in situ gold recovery practices in chloride leaching may give the cyanide-free processing options a competitive edge.

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

Metals ◽

10.3390/met10091216 ◽

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.

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Pre concentration and pressure oxidation of Porgera refractory gold ore

Mining Metallurgy & Exploration ◽

10.1007/bf03402481 ◽

1986 ◽

Vol 3 (4) ◽

pp. 201-208 ◽

Cited By ~ 1

Author(s):

D. R. Weir ◽

J. A. King ◽

P. C. Robinson

Keyword(s):

Pressure Oxidation ◽

Gold Ore ◽

Refractory Gold

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Comparison of gold recovery from refractory gold ore by different processes

Advances in Energy Equipment Science and Engineering ◽

10.1201/b19126-530 ◽

2015 ◽

pp. 2739-2742

Author(s):

Guiying Zhou ◽

Biao Wu ◽

Wenjuan Li ◽

Yongsheng Song

Keyword(s):

Gold Recovery ◽

Gold Ore ◽

Refractory Gold

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The Separation of Carbonaceous Matter from Refractory Gold Ore Using Multi-Stage Flotation: A Case Study

Minerals ◽

10.3390/min11121430 ◽

2021 ◽

Vol 11 (12) ◽

pp. 1430

Author(s):

Sugyeong Lee ◽

Charlotte E. Gibson ◽

Ahmad Ghahreman

Keyword(s):

Treatment Method ◽

Single Stage ◽

Carbonaceous Matter ◽

Flotation Concentrate ◽

Gold Ore ◽

Fine Grained ◽

Multi Stage ◽

Refractory Gold ◽

Pre Treatment ◽

Concentrate Grade

As a pre-treatment method of refractory gold ore, carbonaceous matter (C-matter) flotation was investigated with multi-stage flotation by rougher, scavenger, and cleaner stages. Different dosages of kerosene and MIBC (4-Methyl-2-pentanol) were applied and the optimum dosage was selected by testing in each flotation stage. With the combination of each stage, four circuit designs were suggested, which were a single-stage rougher flotation (R), rougher-scavenger flotation (R+S), rougher-scavenger-scavenger cleaner flotation (R+S+SC), and rougher-rougher cleaner-scavenger-scavenger cleaner flotations (R+S+RC+SC). The results indicated that the scavenger flotation increased C-matter recovery but reduced C-matter grade compared with single-stage rougher flotation. Cleaning of the scavenger flotation concentrate improved C-matter grade significantly, but reduced recovery slightly. Cleaning of the rougher flotation concentrate achieved overall improved selectivity in flotation. A combination of rougher-scavenger flotation followed by cleaning of both concentrates (R+S+RC+SC) resulted in 73% C-matter recovery and a combined cleaner concentrate grade of 4%; the final tailings C-matter grade was 0.9%, where the C-matter remaining in the tailings was locked, and fine grained. The results demonstrate the need for the multi-stage flotation of C-matter from refractory gold ore to achieve selective separation and suggested the potential of C-matter flotation as the pre-treatment for efficient gold production.

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