The effect of iron and oxidizing flux addition on the fire assay of low grade pyritic refractory gold ores

In this study, experiments were conducted to understand the effects of different quantities of additional iron and oxidizing flux (Na2O2) on the direct fire assay of low grade pyritic refractory gold ores instead of performing any pre-treatment like roasting before fire assay. A portion of the pyritic ore was primarily roasted using a rotary kiln to remove sulphur content for the comparison of the results obtained from direct fire assay of the pyritic ore. Then, fire assay process was performed to the roasted ore and gold and silver content in the ore was determined. Unroasted ore specimens were fused by using fluxes and PbO, which accumulates the precious metals, with various quantities of iron. Correlation between the quantity of additional iron and the recovery of gold-silver were investigated. Various quantities of Na2O2, as an oxidizing flux, were added to the smelting charge with iron additions, from which the highest gold and silver recoveries were obtained from previous experiments. From the results, it was clear that the increase in additional iron and Na2O2 quantities was the reason for the increase in the recovered amounts of lead, gold and silver during the process.

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Aeration pretreatment of low grade refractory gold ores

Mining Metallurgy & Exploration ◽

10.1007/bf03403277 ◽

1990 ◽

Vol 7 (1) ◽

pp. 22-29 ◽

Cited By ~ 1

Author(s):

R. W. Bartlett

Keyword(s):

Low Grade ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold

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Enzymatic Pre-Treatment of Carbonaceous Matter in Preg-Robbing Gold Ores: Effect of Ferrous Ion Additives

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.262.43 ◽

2017 ◽

Vol 262 ◽

pp. 43-47

Author(s):

Kojo T. Konadu ◽

Keiko Sasaki ◽

Kwadwo Osseo-Asare ◽

Takashi Kaneta

Keyword(s):

Hydrogen Peroxide ◽

Activated Carbon ◽

Aromatic Compounds ◽

Ferrous Ion ◽

Alkaline Solutions ◽

Carbonaceous Matter ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold ◽

Pre Treatment

The bio-treatment of double refractory gold ores (DRGO) to reduce preg-robbing needs to account for the heterogeneity of the ore so as to acquire a much more complete picture of the system. To this end, the effects of ferrous ion additives on the degradation of powdered activated carbon (PAC) by cell-free spent medium (CFSM) was studied. Au(CN)2- adsorption and Raman spectrometric results suggest that the ferrous salt could have possibly reacted with some biogenic hydrogen peroxide to aid in the degradation of PAC. The bio-treatment produced mixed solid residues containing some partially degraded aromatic compounds which were soluble in alkaline solutions. Ultimately, biodegradation of PAC using CFSM in the presence of 50 µM FeSO4.7H2O for 7 days followed by washing with 3 mM NaOH reduced Au(CN)2- uptake by 80%.

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Investigations of accelerating parameters for the biooxidation of low-grade refractory gold ores

Minerals Engineering ◽

10.1016/s0892-6875(00)00137-0 ◽

2000 ◽

Vol 13 (14-15) ◽

pp. 1543-1553 ◽

Cited By ~ 18

Author(s):

T.L Deng ◽

M.X Liao ◽

M.H Wang ◽

Y.-W Chen ◽

N Belzile

Keyword(s):

Low Grade ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold

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Biooxidation of High-Sulfur Refractory Gold Concentrate by Ferroplasma acidiphilum

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.997.642 ◽

2014 ◽

Vol 997 ◽

pp. 642-645 ◽

Cited By ~ 1

Author(s):

He Shang ◽

Jian Kang Wen ◽

Biao Wu

Keyword(s):

Pulp Density ◽

Cyanide Leaching ◽

Gold Extraction ◽

Pressure Oxidation ◽

Gold Ores ◽

Refractory Gold Ores ◽

Refractory Gold ◽

Initial Ph ◽

Pre Treatment ◽

Number Of Bacteria

Gold ores can be categorized into two types-free milling and refractory. Free milling ores are easy to treat. Gold in such ores is recovered by gravity separating techniques or direct cyanidation. Refractory gold ores, on the contrary, are difficult to treat and require pre-treatment prior to cyanidation, such as roasting, pressure oxidation, fine grinding and biooxidation. A number of bacteria are used in biomining but the prominent ones that are known to be involved in the oxidation of sulfide ores include Thiobacillusferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans. In this study, the gold concentrate was biooxidized in a reactor at 45°C over a period of 10 days at a pulp density of 15% solids using a culture of already grown Ferroplasma acidiphilum. The initial pH was adjusted to 1.5 with sulfuric acid, resulted in 85.39 % oxidation of sulfur from initial grade of 33.83 %, and the slag rate was 68.52 %. The products of sulfide biooxidation were leached at a pulp density of 20 %(v/w) for 24 h at pH 11. The pH was adjusted using CaO and cyanide strength was 10 kg/t, we got a gold extraction of 90.71 %, which ncreaseed 80.09 % compared with the direct cyanide leaching.

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