high pressure oxidation of refractory gold minerals

diergetos326.jpg" />

Iron oxides such as hematite, and magnetite, and iron oxy-hydroxides such as goethite and ferrihydrite were observed in oxidized ore residues, indicating a high level of iron and sulphur oxidation. Four iron-sulphide-containing gold ores from the White Mountain mine in the Jilin Province, China were studied to examine the benefits of using oxidative treatment prior to conventional cyanidation to leach gold.diergetos78.jpg" /> Pressure hydrometallurgy including pressure oxidation (POX) for refractory gold ores and high pressure acid leach (HPAL) for nickel-cobalt laterite processing.

Get Price
diergetos344.jpg" />

Scaleup of Pressure Oxidation Processes onemine

Jan 01, 2016The successful commercialization of a pressure oxidation (POX) process for recovering metal values, including gold, copper, zinc, nickel and molybdenum, is the result of a carefully planned development program.diergetos246.jpg" />

Gold extraction from refractory gold ores requires a pre-treatment process such as roasting, pressure oxidation, or bacterial oxidation to destroy the host sulfide so that the gold is liberated and made available for cyanide leaching. Roasting and pressure oxidation diergetos344.jpg" />

Jan 01, 2016The successful commercialization of a pressure oxidation (POX) process for recovering metal values, including gold, copper, zinc, nickel and molybdenum, is the result of a carefully planned development program.diergetos355.jpg" />

Pressure oxidation (POX) at elevated temperature (110-225oC) and pressure (0.4-3 MPa) has been widely used for oxidising pyrite to liberate gold and precious metals from refractory ores for further processing. The technology has been practised for over 20 years at Lihir (PNG), Porgera (PNG) and MacCraes (NZ) mines to recover gold from refractorydiergetos12.jpg" />

An usual approach for processing complex refractory gold ores is a pre-oxidation treatment prior the gold leaching step and the most known options are roasting, pressure oxidation and bioxidation 6-8. Pressure oxidation is a technology where sulfuric acid can play an important role for oxidising arsenopyrite effectively 9-11. Biological processes are a reality as production technologies chosen for a significant diergetos113.jpg" />

Im mining reported that the Board of Polymetal International has approved the expansion of pressure oxidation operations at its operations in Russia and authorised the immediate start of

diergetos108.jpg" />Published in Materials Research-ibero-american Journal of Materials 2001Authors M AlmeidaAffiliation University of Porto

Acid Pressure Oxidation of Arsenopyrite Part I, Reaction

AbstractThe aqueous pressure oxidation of arsenopyrite particulates in sulphuric acid solution was investigated in the temperature range 130 to 180C and at 10 atm (1013.2 kPa) O2 partial pressure. In addition to temperature, the effects of time, acidity and slurry density on the reaction chemistry have also been determined.diergetos118.jpg" />

Ozone has a very high oxidation potential (2. 07 V) compared with hydrogen peroxide (1.77 V) and chlorine (1.4 V), making it advantageous to use in several applications (Rice, 1997). Importantly, ozone can create favorable conditions to oxidize sulphide minerals in aqueousdiergetos108.jpg" />Published in Materials Research-ibero-american Journal of Materials 2001Authors M AlmeidaAffiliation University of Porto

AbstractThe aqueous pressure oxidation of arsenopyrite particulates in sulphuric acid solution was investigated in the temperature range 130 to 180C and at 10 atm (1013.2 kPa) O2 partial pressure. In addition to temperature, the effects of time, acidity and slurry density on the reaction chemistry have also been determined.diergetos7.jpg" />

- High-pressure oxidation of refractory gold ores in autoclaves Decarbonization Cyanidation (with periodical sampling and analysis of NaCN concentration) Laboratory Assistant National mineral resources university (University of mines) Bachelor's degree, Metallurgy. 2013 2017.diergetos83.jpg" />

high pressure oxidation gold BINQ Mining. 2013-03-07 High pressure oxidation of refractory gold minerals Mining, Many researches consider this process as the best alternative to the treatment of refractory material containing gold and silver, mainly when the precious metals are, diergetos352.jpg" />

Chemical oxidation using nitric acid at ambient pressure and temperature has also been used on a limited basis. Other ore types considered refractory include Carbonaceous ores that allow cyanide to dissolve gold but quickly adsorb gold back onto the active carbon in the ore.diergetos353.jpg" />

The aqueous pressure oxidation of arsenopyrite particulates in sulphuric acid solution was investigated in the temperature range 130 to 180C and at 10 atm (1013.2 kPa) O 2 partial pressure. In addition to temperature, the effects of time, acidity and slurry density on diergetos166.jpg" />

From acidulation the slurry passes to the autoclaving circuit. High-pressure oxidation of refractory gold ores and concentrates is performed in order to enhance their amenability to cyanide leaching. Oxidation conditions are critical to the chemistry within the autoclave and can significantly affect gold diergetos311.jpg" />

May 28, 2002During conventional pressure oxidation of sulfide gold ores, the mineral material feed is introduced into only the first in series of the compartments. Oxygen gas is typically added to each of the compartments and oxidation of sulfide minerals proceeds to a greater extent as the slurry moves from compartment to compartment through the autoclave.

diergetos227.jpg" />

The development of a jet reactor for the leaching of

refractory sulphides only renders about 60% of the refractory gold amenable to subsequent cyanidation. Other techniques developed for the treatment of sulphidic refractory gold ores include pressure oxidation and bacterial oxidation. Throughout the 1970s and 1980s Gencor (South Africa) worked on the development of bacterial oxidation for sulphidic refractory gold ores and in 1986 a 10 ton/day plantdiergetos135.jpg" />Published in American Mineralogist 2013Authors Dogan Paktunc Juraj Majzlan Lukas Palatinus J E Dutrizac Mariana KlementovaAffiliation Schiller International UniversityAbout Hydrometallurgy Arsenic Sulfate Arsenate

(often referred to as solid solution or refractory gold). Gold ore recoveries depend on whether they are free-milling or refractory. The former type yield gold recoveries greater than 90%, while the latter yield recoveries below 80% owing to their high percentage content of sub-microscopic gold particles (7). Traditional gold diagnostic leaches use a combination of sodium cyanide and aciddiergetos227.jpg" />

refractory sulphides only renders about 60% of the refractory gold amenable to subsequent cyanidation. Other techniques developed for the treatment of sulphidic refractory gold ores include pressure oxidation and bacterial oxidation. Throughout the 1970s and 1980s Gencor (South Africa) worked on the development of bacterial oxidation for sulphidic refractory gold ores and in 1986 a 10 ton/day plantdiergetos294.jpg" />

The main pretreatment options for "unlocking" the gold from refractory ores are chemical, biological, pressure oxidation, thermal and physical treatment. The figure below indicates the various pretreatment options before cyanidation can occur for refractory ores.diergetos184.jpg" />

The gold content of the ore sample, coming from Bolivia, was of 10 g ty1 Au. After 24 h leaching time by direct cyanidation, low gold recovery was obtained Ž- 20% Au., with a high reagent consumption. On the other hand, a high gold recovery was achieved for the biooxidated samples after 24 h cyanidation gold dissolution reached about 91% Au.diergetos242.jpg" />

For instance, approximately 15-20 per cent of the world's current gold production involves refractory ores that must be pre-treated prior to downstream recovery by cyanidation. Ores are refractory for many reasons but commonly because gold occurs as tiny inclusions or diergetos28.jpg" />

is in pressure oxidation (POx). POx is usually used in the recovery of gold from refractory ores. Figure 2 shows the typical temperature and pressure ranges for HPAL and POx. High pressure acid leaching (HPAL) 35 65 Min Pressure (Bar) Max Pressure (Bar) 200 275 Min temperature (C) Max temperature (C) Pressure oxidation (POx) 10 35diergetos320.jpg" />

roasting or pressure oxidation. Roasting produces off-gases containing sulfur dioxide and arsenic trioxide, which requires later expensive treatment. The other methods require high pressure, high temperature and/or corrosion-resistant materials. Biological oxidation (biooxidation) as pre-treatment of refractory gold ores is based on the