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This study was undertaken to evaluate the nitric acid leaching as a potential pre-treatment process prior to cyanidation of refractory gold/silver ores. ... A Preliminary Study on Nitric Acid Pre ...

This study was therefore aimed at investigating the ability of the CM-deactivating fungus, P. chrysosporium, to also solubilize/oxidize sulfides found in refractory gold ores so as to assess the potential of a single-stage process for the pretreatment of double refractory gold ores. 2. Experimental investigations 2.1. Materials

Recovery of gold increased gradually to its maximum value of 93.05% as the value of cyanide strength increased from 0.8 to 1.2% and the addition of sodium nitrite raise to 1.2 M. No improvement for further addition of nitrites. This introduction of new hydrometallurgical pre-treatment process has given more option for treating refractory ores.

Abstract: Gold telluride ores are important gold refractory ores due to the presence of sulfides and other gangue materials. ores. For the conventional cyanide leaching process, pretreatment such as oxidation is required to achieve high gold recovery. Roasting is .. process of gold telluride ores from a KCGM flotation con.

In the biooxidation process, bacteria partially oxidize the sulfide coating covering the gold microparticles in ores and concentrates. In this way, gold recovery from refractory minerals can increase from 15-30% to 85-95%. In the last 15 years at least ten large-scale commercial gold processing units have been established in South Africa ...

As free-milling oxide deposits are depleted on a world-wide scale, the mining companies capable of efficiently mining and processing both low- and high-grade refractory sulfide deposits will become industry leaders. This chapter addresses a new process for the biooxidation of refractory gold ores developed by GeoBiotics, Inc.

ALKALINE OXIDATIVE LEACHING OF GOLD-BEARING ARSENOPYRITE ORES By P. Bhakta,1 J. W. Langhans, Jr.,1 and K. P. V. Lei2 ABS"rRACT The U.S. Bureau of Mines developed an alkaline oxidative pretreatment leaching procedure to increase the recovery of gold from arsenopyrite (FeAsS) ores. The best solution compositions for

highly refractory ores, the processed gold ore should be pretreated before leaching. Without pretreatment process the gold recovery degree can remain under 50 % or for moderately refractory ores in the range of 50-80 %. In these cases, to increase the recovery degree to acceptable levels (over 80 %), pretreatment

A "refractory" gold ore is an ore that has ultra fine gold particles disseminated throughout its gold occluded minerals. These ores are naturally resistant to recovery by standard cyanidation and carbon adsorption processes. These refractory ores require pre-treatment in order for cyanidation to be effective in recovery of the gold.

grades for refractory resources. We believe ROL for gold has this potential." FL is pioneering Rapid Oxidative Leach (ROL), which is a mechano-chemical pre-treatment process for refractory gold ores. Sally Rocks, senior R&D chemist believes her team has made an extraordinary breakthrough which will have a profound effect on the industry. "We

and Otto, 1980), and on the oxidative leaching of copper ores (Roca et al., 2000). In this research work the use of ozone is proposed as oxidative pretreatment for gold and silver refractory ores with the aim of modifying the pyritic matrix and thus exposing the precious metals to .

FL is pioneering a mechano-chemical pre-treatment process known as the Rapid Oxidative Leach (ROL) for refractory gold ores. Sally Rocks, senior R&D chemist believes her team has made an extraordinary breakthrough which will have a profound effect on the industry.

leaching circuits, even when the ore is finely ground. The cause of low gold recoveries can be either through the presence of naturally occurring 'preg robbing' carbonaceous materials or gold physically 'locked' in sulphide minerals. The majority of gold ores are classified refractory because the gold mineralogy is contained in sulphides.

Refractory gold ore pretreatment Treatment of refractory gold ore (whole ore and flotation concentrates) has become more prominent since the 1980s, with many gold discoveries often including ores that are wholly or partially refractory. Refractory pre-treatment processes include pressure oxidation, biological oxidation and various forms of ...

The reasons of gold refractory, ore classification, and preprocessing methods. I.The reason of the gold mineral refractory. There are so many types of reasons that caused the difficulty of gold ore processing, including physical element, chemical element, and mineralogical element.

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It's now over 10 years since the European Patent Office advised its decision to grant Maelgwyn Mineral Services Ltd (MMS) a European Patent for its Leachox process for the treatment of refractory gold ores. Since that time the process route has become the industry leader in the low-cost recovery of gold from refractory and sulphide orebodies.

reach it in cyanide leaching process. 2) The gold ores with As must be broken or decomposed in the gold particles scales, so that gold is fully exposed, and then extracted with the appropriate gold leaching agent. The process of crushing or decomposition before gold leaching is called pretreatment of refractory gold.

Gold ores are considered refractory if gold extractions from a conventional cyanidation process are less than 80% even after fine grinding. 1) Arsenic-bearing refractory gold ore has stones extremely difficult to deal with. In the stones, gold is locked up in arsenic mineral matrix as the form of microscopic or submicroscopic lattice.

and reagent concentration (Na2S and to eliminate penalty elements includ- In this study, the alkaline sulfide pre- NaOH) on the pretreatment process ing As and Sb from ores/concentra- treatment of a highly refractory gold/ and cyanide leaching of gold and silver tates.23,24 In this respect, Ficeriová et silver ore containing antimonial sul ...

Metallurgical ContentGold Leaching & Processing of Arsenic OreMispickel (Arsenopyrite: FeAsS).6Leaching and Recovering Gold from Antimony MineralsStibnite (Antimony Sulphide, Sb2S2)Telluride Gold Ore ProcessingSolubility of TelluridesGold Extraction from Carbonaceous OreList Gold Refractory Process Methods Where gold is associated with arsenic, antimony, tellurium, and .

The pretreatment of an antimonial refractory gold and silver ore was investigated using alkaline sulphide leaching. The ore assayed 20 g/t Au and 220 g/t Ag and contained predominantly quartz/clay and barite, and to a lesser extent, sulphides such as pyrite, stibnite, sphalerite, zinkenite (Pb 9 Sb 22 S 42) and andorite (Sb 3 PbAgS 6).The latter mineral was identified to be the most important ...

BACTERIAL LEACHING AS A PRE-TREATMENT STEP FOR GOLD ... FOR GOLD RECOVERY FROM REFRACTORY ORES ... This leaching process decomposes the sulfide matrix, thus exposing the encapsulated precious metals to leaching solution.

Refractory gold processes . A "refractory" gold ore is an ore that is naturally resistant to recovery by standard cyanidation and carbon adsorption processes. These refractory ores require pre-treatment in order for cyanidation to be effective in recovery of the gold. A refractory ore generally contains sulfide minerals, organic carbon, or both.
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