Non-cyanide reagents for gold extraction from the products of pressure oxidation of sulphide concentrates

2021 ◽  
pp. 37-44
Author(s):  
A. V. Epiforov ◽  
S. V. Balikov ◽  
A. A. Lukianov ◽  
A. A. Shipnigov
Keyword(s):  
Gold Extraction ◽  
Pressure Oxidation

Biooxidation of High-Sulfur Refractory Gold Concentrate by Ferroplasma acidiphilum

2014 ◽  
Vol 997 ◽  
pp. 642-645 ◽  
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.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

Formation of defects in implanted hipox-structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1406-1407
Author(s):  
Peter Pegler ◽  
N. David Theodore ◽  
Ming Pan
Keyword(s):  
High Pressure ◽  
Cross Section ◽  
Semiconductor Devices ◽  
Silicon Substrates ◽  
Processing Conditions ◽  
Pressure Oxidation ◽  
Deep Trench ◽  
Local Oxidation ◽  
Trench Isolation ◽  
And Behavior

High-pressure oxidation of silicon (HIPOX) is one of various techniques used for electrical-isolation of semiconductor-devices on silicon substrates. Other techniques have included local-oxidation of silicon (LOCOS), poly-buffered LOCOS, deep-trench isolation and separation of silicon by implanted oxygen (SIMOX). Reliable use of HIPOX for device-isolation requires an understanding of the behavior of the materials and structures being used and their interactions under different processing conditions. The effect of HIPOX-related stresses in the structures is of interest because structuraldefects, if formed, could electrically degrade devices.This investigation was performed to study the origin and behavior of defects in recessed HIPOX (RHIPOX) structures. The structures were exposed to a boron implant. Samples consisted of (i) RHlPOX'ed strip exposed to a boron implant, (ii) recessed strip prior to HIPOX, but exposed to a boron implant, (iii) test-pad prior to HIPOX, (iv) HIPOX'ed region away from R-HIPOX edge. Cross-section TEM specimens were prepared in the <110> substrate-geometry.

Recovery of gold from sulfide refractory gold ore: Oxidation roasting pretreatment and gold extraction

2021 ◽  
Vol 164 ◽  
pp. 106822
Author(s):  
Hong Qin ◽  
Xueyi Guo ◽  
Qinghua Tian ◽  
Dawei Yu ◽  
Lei Zhang
Keyword(s):  
Gold Extraction ◽  
Gold Ore ◽  
Refractory Gold

scholarly journals Performance-Based Selection of the Cathode Material for the Electrodeposition-Redox Replacement Process of Gold Recovery from Chloride Solutions

2021 ◽  
Author(s):  
Ivan Korolev ◽  
Kirsi Yliniemi ◽  
Mari Lindgren ◽  
Leena Carpén ◽  
Mari Lundström
Keyword(s):  
Material Selection ◽  
Recovery Process ◽  
Multiple Attribute Decision Making ◽  
Gold Recovery ◽  
Process Efficiency ◽  
Gold Extraction ◽  
Corrosion Properties ◽  
Multiple Attribute ◽  
Replacement Process ◽  
Cathode Substrate

AbstractRecently, an emerging electrodeposition-redox replacement (EDRR) method was demonstrated to provide exceptionally efficient gold recovery from cyanide-free hydrometallurgical solutions. However, the effect of electrode material and its corrosion resistance in this process was overlooked, even though the EDRR process is carried out in extremely corrosive, acidic chloride solution that also contains significant amounts of strong oxidants, i.e., cupric ions. In the current study, nickel alloy C-2000, stainless steels 316L and 654SMO, and grade 2 titanium were for the first time critically evaluated as potential cathode materials for EDRR. The particular emphasis was placed on better understanding of the effect of cathode substrate on the overall efficiency of the gold recovery process. The use of a multiple attribute decision-making method of material selection allowed reaching of a well-founded compromise between the corrosion properties of the electrodes and process efficiency of gold extraction. The 654SMO steel demonstrated outstanding performance among the examined materials, as it enabled gold recovery of 28.1 pct after 3000 EDRR cycles, while its corrosion rate (CR) was only 0.02 mm/year.

scholarly journals Underground Multiculturalism: Contentious Cultural Politics in Gold-Mining Regions in Chocó, Colombia

2020 ◽  
pp. 1-28
Author(s):  
Jesse Jonkman
Keyword(s):  
Cultural Politics ◽  
Gold Mining ◽  
Political Life ◽  
Mining Activities ◽  
Unique Form ◽  
Gold Extraction ◽  
Mining Regions ◽  
Instrumental Role ◽  
Community Councils

Abstract This article maps the contentious forms of political life that emerge when multicultural rights and non-formal gold extraction coincide. Specifically, it shows how, in the Colombian department of Chocó, Afro-descendant community councils have produced a unique form of mining governance that, while depending for its legitimacy on everyday uses of Afro-Colombian legislation, consists of the organisation, taxation and policing of mining activities that are in tension with official notions of extractive and multicultural law. In exploring such ‘underground’ cultural politics, the article highlights the limits of state-centric analyses of ‘neoliberal multiculturalism’ and, accordingly, underscores the instrumental role that governed subjects play in the on-the-ground unfolding of multicultural governance regimes.

The Effect of Ge Segregation on Oxidation of Si

1987 ◽  
Vol 105 ◽  
Author(s):  
E. C. Frey ◽  
N. R. Parikh ◽  
M. L. Swanson ◽  
M. Z. Numan ◽  
W. K. Chu
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Epitaxial Layer ◽  
Atmospheric Pressure ◽  
Oxidation Rate ◽  
Oxidation Temperature ◽  
Pressure Oxidation ◽  
Enhanced Oxidation ◽  
High Pressure Oxidation

AbstractWe have studied oxidation of various Si samples including: Ge implanted Si, CVD and MBE grown Si(0.4–4% Ge) alloys, and MBE grown Si-Si(Ge) superlattices. The samples were oxidized in pyrogenic steam (800–1000°C, atmospheric pressure) and at low temperature and high pressure (740°C, 205 atm of dry O2). The oxidized samples were analyzed with RBS/channeling and ellipsometry.An enhanced oxidation rate was seen for all Ge doped samples, compared with rates for pure Si. The magnitude of the enhancement increased with decreasing oxidation temperature. For steam oxidations the Ge was segregated from the oxide and formed an epitaxial layer at the Si-SiO2 interface; the quality of the epitaxy was highest for the highest oxidation temperatures. For high pressure oxidation the Ge was trapped in the oxide and the greatest enhancement in oxidation rate (>100%) was observed.

A high selective ion-imprinted polymer grafted on a novel nanoporous material for efficient gold extraction

2013 ◽  
Vol 36 (11) ◽  
pp. 1826-1833 ◽  
Author(s):  
Elahe Moazzen ◽  
Homeira Ebrahimzadeh ◽  
Mostafa M. Amini ◽  
Omid Sadeghi
Keyword(s):  
Nanoporous Material ◽  
Ion Imprinted Polymer ◽  
Imprinted Polymer ◽  
Gold Extraction ◽  
Ion Imprinted
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