A typical challenge encountered on most gold processing plants during leaching of refractory ores is the reduction in recovery due to the presence of carbonaceous matter which preg-robs dissolved ...

Leaching of Sb 2 S 3 ore in an alkaline system involves the combination of sodium sulphide (Na 2 S) and sodium hydroxide (NaOH) to form a solution of sodium thioantimonite as shown in reactions 1 ...

With a telluride-type gold ore flotation concentrate as the research object, the Na2S + NaOH collaborative leaching process was applied to selectively separate tellurium …

Liberation: Cyanide leaching will only be effective if the cyanide can come in contact with the gold particle. For this to happen, the ore should either be sufficiently porous for cyanide to reach the gold, or more usually the ore is crushed and ground to a size at which the surface of the gold is exposed – i.e. the gold is liberated.

In this paper, the removal of arsenic from arsenic-bearing gold ore through air oxidation and sodium hydroxide leaching with microwave irradiation was studied. Firstly, single-factor experiments were carried out. The results indicated that the removal rate of arsenic was influenced by the sodium hydroxide concentration, ratio of liquid to solid, …

2,4 h, and 2M NaOH solution in a 2-L autoclave. Cyanidation of the leach residues resulted in 90 to 93 pct Au and 60 to 80 pct Ag extractions, compared with only 5 and 15 pct, respectively, without the pretreatment. The procedure was further tested by leaching a low-grade gold ore and a bulk sulfide flotation concentrate prepared from it.

Here the equilibrium concentration of dissolved gibbsite, i.e. Al(OH)3, is plotted as a function of temperature for various concentrations of NaOH. Note that the solubility is …

preg-robbing ability of carbonaceous ores has been based on tests with gold cyanide leach, or gold spiked solutions. The amount of gold removed from solution by the ore …

Cyanide is a lixiviant, or reagent that is used to leach, often in tanks, gold from a solid matrix and form a gold cyanide complex. The gold cyanide complex is then extracted from the pulp or slurry by adsorption onto activated carbon. CIL stands for carbon-in-leach. This is a gold extraction process called cyanidation where ... Gold …

The results are also consistent with our previous gold leaching behaviour studies (Asamoah et al., 2018), showing a sharp drop in the gold leaching rate after cyanide leaching for 240 min. Fig. 11 shows a schematic representation of the predominant particle–particle interactions occurring during cyanide leaching with sodium hydroxide …

Heap or vat leaching is a process that has been extensively used for the recovery of valuable metals like copper, gold (Au) and silver. The ore is prepared for vat leaching by either crushing or ...

The rates of arsenic extraction for high-grade ore A in a 2M NaOH solution at 140 psig O2 were determined at 80°, 100°, and 140° C (fig. 4). ... The principal advantage of the alkaline oxidative leaching for …

The reactions that take place during the dissolution of gold in cyanide solutions under normal conditions have been fairly definitely established. Most agree …

Eighty-three percent of the gold and 53 pct of the silver were floated. Leaching of the flotation concentrate at 100° C, 2M NaOH, 10 pct solids, 140 psig O2, and 4 h resulted …

CN − and HCN speciation as a function of pH (a) ... is added to the ore during the transfer process, typically via screw feeder from a lime silo directly onto an ore transfer conveyer belt, before being stacked on the cyanidation heap leaching pad. ... Alternative Lixiviants to Cyanide for Leaching Gold Ores. Gold Ore Processing …

This article will focus on the alkaline leaching of gold-bearing tetrahedrite concentrate in a solution containing sodium sulfide and sodium hydroxide. This selective leaching is followed by the leaching of heavy and waste metals into the solution, which may influence the physical properties and quality of the desired product, possibly …

CHARACTERIZATION OF JAROSITE FORMED DURING BIOOXIDATION OF REFRACTORY GOLD ORES AND ITS EFFECT ON CYANIDE CONSUMPTION DURING GOLD LEACHING BY MICHAEL KANDENGWA SUPERVISED BY PROFESSOR RF SANDENBERGH A dissertation submitted in partial fulfilment of the requirements for the …

Leaching, often gold, is the process of extracting a soluble constituent from a solid by means of a solvent. In extractive metallurgy, of gold, it is the process of dissolving a certain mineral (or minerals) from an ore or a concentrate, or dissolving certain constituents from materials such as a calcines, mattes, scrap alloys, anodic slimes, etc., …

With a telluride-type gold ore flotation concentrate as the research object, the Na2S + NaOH collaborative leaching process was applied to selectively separate tellurium before the cyanide ...

In alkaline solutions, peroxide has been evaluated as an oxidant primarily for the leaching of gold in cyanide solutions (Ball et al., 1989; Nugent et al., 1991; Lorosch et al., 1989) and uranium in carbonate solutions (Burkin et al., 1981; Monhemius, 1992). Peroxide is an intermediate in the reduction of dissolved oxygen.

Fig. 2 — Residual gold concentration in the Fairview ore as a function of the leaching time. During the 17 week testwork period, the PAL process enabled the extraction of all …

To investigate the relationship between metal ions and pH value during leaching of antimony-bearing gold ores under an alkaline sodium sulphide system, ... Na 2 S content of 80 g/L, wash water ratio of 3.0, and stirring at 65 °C for 30 min, the inhibited effect of NaOH concentration on leaching of gold and antimony was investigated, ...

The slurries were filtered and the solids subjected to cyanidation tests using lime to readjust the pH. Arsenic-bearing refractory gold ore 157 Arsenic was solubilized during the NaOH leach, as concentrations in the caustic leach filtrate were 1.5 to 2.0 g/L, with essentiaUy all arsenic in the pentavalent oxidation state.

preg-robbing ability of carbonaceous ores has been based on tests with gold cyanide leach, or gold spiked solutions. The amount of gold removed from solution by the ore indicates the capacity of the ore to adsorb gold from solution. From these results a value or index is calculated based on the gold concentration remaining or removed from solution.

Firstly, the refractory ore was pretreated with sodium hydroxide under ultrasound. Secondly, the pretreated ore was leached under ultrasound. The leaching ratio of gold decreased …

In alkaline solutions, peroxide has been evaluated as an oxidant primarily for the leaching of gold in cyanide solutions (Ball et al., 1989; Nugent et al., 1991; Lorosch …

A new mathematical model was developed for leaching of zinc ores containing silicates such as hemimorphite which produce a gel during leaching with sulfuric acid.

The effect of pulp density from 100 to 600 g/L was investigated to determine the highest pulp density at which arsenic content in the samples could be successfully reduced to below 0.5 wt.% within 6 h of leaching time, while keeping NaHS/NaOH additions at 100 g/L and leaching temperature constant at 80 °C.

Request PDF | Alternative lixiviants to cyanide for leaching gold ores | Over 25 alternative lixiviant processes to cyanide have been tested in the laboratory; some of which have been successful ...

This thesis aims to show the methodology of new leaching processes, point out possible alternatives in the market for processing raw materials and approach the research process of new reagents on samples from waste after flotation processing of gold ores.