Refractory gold ores: Challenges and opportunities for a key …

High-grade refractory gold reserves offer the potential for lower costs per ounce despite higher capital and operational costs. A focus on three action areas can …

The process mineralogy of gold: The classification of ore …

However, refractory and double refractory ores are not easily treated by cyanidation because gold is locked within the sulfide minerals in refractory ores (Natarajan, 2018;Norgate and Haque, 2012 ...

Microbial pre-treatment of double refractory gold ores

roasting This is the current industry standard for simultaneously destroying the carbonaceous matter while oxidizing sulfide minerals in double refractory gold ores. This process is generally, but not always, successful and depends upon the temperature of roasting. Very high temperatures are often required to combust some preg robbing …

Complete gold extraction and recovery from double refractory gold ores

Double refractory gold ores (DRGOs), which are carbonaceous refractory gold ores, are a more challenging target than non‑carbonaceous ores (Konadu et al., 2020). Carbonaceous refractory gold ores not only require pretreatment to liberate gold grains, but also require the removal and/or decomposition of carbonaceous matter to …

Establishing thE ProcEss MinEralogy of gold orEs

refractory gold can only be achieved by employing a pre-oxidation process prior to cyanide leaching. Antimony, bismuth sulfide and telluride gold ores: Antimony, bismuth sulfide and telluride gold ores are often somewhat refractory due to the presence of slow-dissolving gold minerals such as aurostibite, maldonite and gold tellurides.

Near-Technical Limit Gold Recovery from a Double …

Exploring Non-ammoniacal Thiosulfate Gold Leaching and Limited Gold

The application of pressure oxidation (POX) followed by thiosulfate gold leaching is an efficient method used to extract gold from double refractory gold ores containing both sulfide and carbonaceous matter. This process is expected to result in high gold recovery rates, as it liberates gold from sulfides and eliminates the preg-robbing …

Transformation of the carbonaceous matter in double refractory gold …

This chapter introduces the mineralogical and chemical changes in the various solid residues produced during a sequential biotreatment, consisting of the liberation of gold from sulfides by an iron-oxidizer and decomposition of carbonaceous matter by lignin-degrading enzymes secreted from a white rot-fungus, which successfully …

Microwave pretreatment of a double refractory gold ore

Double refractory gold ores, such as Barrick's Goldstrike ore, contain both pyrite and carbonaceous matter and the latter results in the loss of gold from solution during cyanide leaching. One possible remedy is to roast the ore and thus oxidize the pyrite and remove the organic carbon. In this research, microwave roasting of a double ...

Extraction of Gold from Refractory Gold-Bearing Ores by …

Pyrometallurgical processing is shown to be promising for treating ores obtained from refractory and double-refractory gold deposits. Problems related to the …

Bio-Oxidation of a Double Refractory Gold Ore and …

Abstract. Carbonaceous sulfidic gold ores are commonly double refractory and thus require pretreatment before gold extraction. In this paper, the capacity of pre-bio …

A two-stage bacterial pretreatment process for double refractory gold ores

Flotation concentrate was obtained from a plant that processes double refractory gold ores. The particle size was 80% passing 75 μm. Sulfur and carbonaceous matter (CM) in the samples were determined using the Leco combustion volumetric method. A LECO titrator SC-444DR was used in this study. The grade of gold was determined …

Microbial pre-treatment of double refractory gold ores

The characteristics of gold ores change with time during exploitation from free-milling to refractory and double refractory gold ores. This prevents extraction of the minerals of interest in ...

MICROBIAL PRE-TREATMENT OF DOUBLE REFRACTORY GOLD ORES

This chapter introduces the mineralogical and chemical changes in the various solid residues produced during a sequential biotreatment, consisting of the liberation of gold from sulfides by an iron-oxidizer and decomposition of carbonaceous matter by lignin-degrading enzymes secreted from a white rot-fungus, which successfully …

Assessing the environmental impact of gold production from double …

A simplified system boundary is also observed in Fig. 2, showing various stages from comminution to electrowinning for producing 1 kg gold from double refractory ores in a roasting process plant. A roasting facility in Nevada was developed to process 12,000 t of double refractory ore daily (Thomas et al., 1997; Thomas and Cole, 2016).

Double-Refractory Carbonaceous Sulfidic Gold Ores

Ores where gold is associated with sulfides and with high carbonaceous matter content are considered double refractory. Ores in the Carlin Trend District are characterized by the presence of ...

Biological pretreatment of carbonaceous matter in double …

The pretreatment of carbonaceous material in double refractory gold ores (DRGO) is necessary to decrease preg-robbing of gold and maximize gold recovery. …

Mycohydrometallurgy: Biotransformation of double refractory gold ores

Double refractory gold ores (DRGO) contain organic carbonaceous matter (CM) and sulfide minerals, and thus require pretreatment before cyanidation for gold extraction. Though there have been several studies into microbial pretreatment of DRGO, available literature indicates that microbial degradation of both sulfides and CM in a …

Significance of Acid Washing after Biooxidation of Sulfides in

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 …

Assessing the environmental impact of gold production from double …

However, refractory and double refractory ores are not easily treated by cyanidation because gold is locked within the sulfide minerals in refractory ores (Natarajan, 2018; Norgate and Haque, 2012; Vaughan, 2004). Furthermore, double refractory ores indicate preg-robbing properties caused by carbonaceous matter in the …

Transformation of the carbonaceous matter in double refractory gold …

Sulfides and carbonaceous matter in double refractory gold ore (DRGO) were bio-treated sequentially using an iron-oxidizing archaeon Acidianus brierleyi followed by lignin peroxidase-dominating crude enzymes released from the white-rot fungus Phanerochaete chrysosporium to significantly improve gold recovery from 24% to 92%.

A two-stage bacterial pretreatment process for double refractory gold ores

For double refractory gold ores which contain sulfide minerals and organic carbonaceous matter, the stage in which to use coaldegrading microorganisms (Amankwah et al. 2005) for degradation of the ...

Microbial Pre-treatment of Double Refractory Gold Ores

Microbial Pre-treatment of Double Refractory Gold Ores. Microbial Pre-treatment of Double Refractory Gold Ores. James Afidenyo. 2008. See Full PDF Download PDF.

Double-Refractory Carbonaceous Sulfidic Gold Ores

Ores where gold is associated with sulfides and with high carbonaceous matter content are considered double refractory. Ores in the Carlin Trend District are characterized by the presence of submicroscopic gold (invisible gold) finely disseminated within a sulfide-rich matrix within carbonaceous material.Sulfide concentrations vary …

Flotation of Carbonaceous Matter from a Double …

The flotation feed used in this study was double refractory gold ore containing both carbonaceous matter and sulfide from Barrick's flagship Goldstrike mine in Nevada, USA. X-ray diffraction (XRD) …

Processing double refractory gold-arsenic-bearing …

1. Introduction. Mining metallurgists classify gold ores into two categories according to their amenability to a conventional "cyanidation-carbon adsorption" gold extraction technology: "free milling" and "refractory" (La Brooy et al., 1994).The former are those ores from which more than 90% of the gold can be extracted by simple gravity …

Near-Technical Limit Gold Recovery from a Double Refractory …

A recent Nevada Gold Mines research program focused on pressure oxidation pre-treatment of a Carlin-type double refractory ore from the Turquoise Ridge Mine. The research team found that both arsenian pyrite and carbonaceous matter were highly oxidized within an hour at 300 °C using a bench-top autoclave reactor and that …

Recovery of gold from sulfide refractory gold ore: Oxidation …

Cyanide-refractory ores constitute 30 % of the world's gold mineral resource base. With the global decrease in the availability of high-grade and free-milling ores, low-quality ores, including ...

Biological pretreatment of carbonaceous matter in double refractory

The refractory gold ores, which contain both gold locking in sulfides and preg-robbing by CM, are classified as a double refractory gold ores, abbreviated as DRGOs (Nanthakumar et al., 2007).