Gold extraction with poly(diallylamine) resins

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.

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

Journal of Latin American Studies ◽

10.1017/s0022216x2000098x ◽

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.

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

Journal of Separation Science ◽

10.1002/jssc.201300147 ◽

2013 ◽

Vol 36 (11) ◽

pp. 1826-1833 ◽

Cited By ~ 8

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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Effect of Temperature on Column Bioleaching of a Refractory Gold Ore

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.825.352 ◽

2013 ◽

Vol 825 ◽

pp. 352-355 ◽

Cited By ~ 3

Author(s):

Zeng Ling Wu ◽

Zhong Sheng Huang ◽

Ren Man Ruan ◽

Shui Ping Zhong ◽

Brenda K.C. Chan

Keyword(s):

Sulfide Oxidation ◽

Effect Of Temperature ◽

Low Grade ◽

Key Factors ◽

Gold Extraction ◽

Gold Ores ◽

Fraction Distribution ◽

Higher Temperature ◽

Liberation Analysis ◽

Main Factor

Low-grade, finely disseminated refractory sulfide gold ores associated with high arsenic are ubiquitous resources all over the world. Since heap bio-oxidation is an economic and promising biotechnology to recover gold, low grade, high organic carbon and arsenic bearing gold ores from Zhesang Mines in China were chosen for this purpose to study the key factors that would affect biooxidation. Pyrite and arsenopyrite (particle size 0.002-0.22 mm) were the main minerals from Mineral Liberation Analysis (MLA). Column biooxidation and cyanidation of mineral size < 10 mm were evaluated for its potential for gold extraction. Results showed that temperature was the main factor influencing sulfide oxidation. 58-67 % of sulfide was oxidized at 35-45°C after > 240 days of biooxidation with mixed mesophiles, while higher sulfide-S dissolution (77%) was obtained at 60°C. Sulfide-S fraction distribution revealed higher mineral decomposition, finer fractions and eventually higher sulfide oxidation at 60°C. Jarosite and scorodite were found from the residues at 60°C by SEM and EDX, which implies higher temperature accelerated arsenic precipitation. No elemental sulfur was detected during the biooxidation at 35-60°C. After bio-oxidation, column cyanidation was successfully demonstrated recovery of gold from the residues, with gold extraction rate reaching 66%.

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Effect of Acid Leaching Pre-Treatment on Gold Extraction from Printed Circuit Boards of Spent Mobile Phones

Materials ◽

10.3390/ma14020362 ◽

2021 ◽

Vol 14 (2) ◽

pp. 362

Author(s):

Nicolò Maria Ippolito ◽

Franco Medici ◽

Loris Pietrelli ◽

Luigi Piga

Keyword(s):

Mobile Phones ◽

Printed Circuit Boards ◽

Acid Leaching ◽

Economic Feasibility ◽

Circuit Boards ◽

Gold Extraction ◽

Printed Circuit ◽

Solid Ratio ◽

Thiourea Complex ◽

Pre Treatment

The effect of a preliminary acid leaching for the recovery of gold by thiourea from printed circuit boards (PCBs) of spent mobile phones, was investigated. Preliminary leaching is aimed to recover copper in the leachate that would compete with gold in the successive leaching of the residue with thiourea, thus preventing the formation of the gold-thiourea complex. Two hydrometallurgical routes were tested for the recovery of copper first, and gold after. The first one was based on a two-step leaching that utilizes sulfuric acid and hydrogen peroxide in the preliminary leaching and then thiourea for the recovery of gold in the successive leaching: A copper and gold recovery of 81% and 79% were obtained, respectively. In the second route, nitric acid was used: 100% of copper was recovered in the leachate and 85% of gold in the thiourea successive leaching. The main operative parameters, namely thiourea and ferric sulphate concentrations, leach time, liquid-solid ratio, and temperature were studied according to a factorial plan strategy. A flowsheet of the processes was proposed, and a mass balance of both routes was obtained. Finally, qualitative considerations on the technical and economic feasibility of the different routes were made.

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Gold Extraction from Cyanidation Tailing Using Microwave Chlorination Roasting Method

Metals ◽

10.3390/met8121025 ◽

2018 ◽

Vol 8 (12) ◽

pp. 1025 ◽

Cited By ~ 3

Author(s):

Fei Zhu ◽

Libo Zhang ◽

Haoyu Li ◽

Shaohua Yin ◽

Sivasankar Koppala ◽

...

Keyword(s):

Microwave Field ◽

High Efficiency ◽

Chloride Concentration ◽

Treatment Method ◽

Gold Extraction ◽

Microwave Roasting ◽

Gold Mines ◽

Chlorination Roasting ◽

New Treatment ◽

Gold Industry

At present, gold mines are increasingly scarce in the world. The yield of cyanidation tailing (CT) of refractory gold ores with a grade of 10 g/T is huge; however, the effective capitalization of the cyanidation tailing is a significant problem in the gold industry. In this work, a new treatment method, a microwave-roasting process developed. The effect of roasting temperature, calcium chloride concentration, holding time and mineral size on the recovery of Au researched under conventional and microwave conditions. It found that, under the same processing conditions, the Au recovery in the microwave field is much higher than that of conventional conditions. The preliminary reinforcing role of the microwave discussed in the recovery of gold. This might be because of the microwave absorption ability of CaCl2 is much better, heated quickly and the reactions intensified among CaCl2, O2, and H2O. As a result, the extraction of gold in CT drastically increased in the microwave field, and the microwave roasting technology shows the characteristics of environmental protection in terms of low energy consumption and high efficiency.

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Housing and population sprawl near tailings storage facilities in the Witwatersrand: 1952 to current

South African Journal of Science ◽

10.17159/sajs.2015/20140186 ◽

2015 ◽

Vol Volume 111 (Number 11/12) ◽

Cited By ~ 7

Author(s):

Melanie A. Kneen ◽

Matthew E. Ojelede ◽

Harold J. Annegarn ◽

◽

...

Keyword(s):

Census Data ◽

Buffer Zone ◽

Housing Development ◽

Aerial Photographs ◽

Population Exposure ◽

Residential Areas ◽

Gold Extraction ◽

Buffer Zones ◽

Quality Dispersion ◽

Storage Facilities

Abstract Mining, tailings storage facilities (TSFs), dust pollution and growth in residential housing development are synonymous with the Witwatersrand, South Africa. Encroachment of housing onto land close to TSFs, i.e. areas rendered marginal because of the dust hazard and risk of structural failure, has continued unabated for decades, intensifying human exposure to windblown mineral dust. Recent research indicates that the finer milling used for modern gold extraction results in aeolian dust emanating from the TSFs which contributes to a higher proportion of inhalable particles in the source material. Air quality dispersion modelling, validated by ambient aerosol monitoring campaigns, indicates that episodic dust events generate particulate matter (PM10) and, specifically, quartz dust concentrations that are unhealthy at distances of up to 2 km downwind from TSFs. This contribution documented residential development from 1952 to 2011 (using historical aerial photographs, census data from 2001 and 2011 and ancillary information) to determine the population exposed to dust emanations from the TSFs. Using the images, land use was classified into residential areas, TSF footprints and open areas, onto which a series of 500 m buffer zone contours were superimposed. The resulting statistics were used to assess the populations exposed to dust hazard within the defined buffer zones. Overall, housing development has experienced a growth of approximately 700% since 1952 at a rate of 14% per year. Analysis of recent monitoring campaign data has confirmed multiple occurrences of quartzrich inhalable dust in residential settings at levels that exceed occupational health standards, extrapolated to values for population exposure.

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Study of the Gold Extraction Using Tetra N-Butyl Ammonium Chloride-Chloroform

Indonesian Journal of Chemistry ◽

10.22146/ijc.21947 ◽

2010 ◽

Vol 1 (2) ◽

pp. 77-80

Author(s):

Yuli Puspito Rini ◽

Agus Kuncaka ◽

Ngatidjo Hadipranoto

Keyword(s):

Experimental Data ◽

Ammonium Chloride ◽

Extraction Efficiency ◽

Extraction Constant ◽

Experimental Result ◽

Gold Extraction ◽

Minimum Concentration ◽

Influence Of Ph ◽

Brown Precipitate

The existence of the AuCl4- ion in the solution as the function of pH before performing the extraction of gold in the system of tetra N-butylammonium chloride (TBACI) -chloroform has been studied. The experimental data showed that AuCl4- ion was hydrolyzed at pH 5-10 and, an amorf dark-brown precipitate was appeared at pH 11-14. Amount of gold in the solution at pH 14 before extraction was around 70%. Study of the extraction has been carried out by investigating the influence of pH and TBACI concentration on the extraction efficiency. The experimental result indicated that TBACI was very efficient extractant for the extraction of gold from aqueous halide with the efficiency higher than 99%. The extraction of Gold in the TBACI-chloroform was effective at pH 0-4 with minimum concentration of TBACI 10-3 M, and the calculated Kex (extraction constant) was 5.07x10-4.

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The Borax Method of Gold Extraction for Small-Scale Miners

Journal of Health and Pollution ◽

10.5696/2156-9614-2.3.5 ◽

2012 ◽

Vol 2 (3) ◽

pp. 5-10 ◽

Cited By ~ 20

Author(s):

Peter W.U. Appel ◽

Leoncio Na-Oy

Keyword(s):

Heavy Metal ◽

Melting Point ◽

Scientific Research ◽

The Philippines ◽

Toxic Element ◽

Heavy Mineral ◽

Small Scale ◽

Gold Extraction ◽

Reducing Costs ◽

Capture Rates

Background. More than ten million small-scale miners (SSM) worldwide use mercury to extract gold, releasing large amounts of the toxic element into the environment. Alternatives to mercury have been suggested over the years to little avail. A group of miners in the Philippines has demonstrated that borax, when used as a flux for smelting gold out of heavy mineral concentrates, is an effective and safer substitute for mercury. Objectives. To present a basic comparison of the mercury amalgamation and borax methods of gold extraction for SSM. Methods. Borax was added to milled ore to reduce the melting point of gold to a level accessible to SSM. The amount of gold captured, and the amount of mercury released into the environment, was compared to two common amalgamation methods: whole ore and heavy metal. Discussion. The borax method appears to capture more gold, as well as eliminate the use of mercury. It is also less expensive. It is important to stop the use of mercury amongst SSM. However, health and environmental arguments alone are not enough to convince miners to switch. The argument of improving gold-capture rates while reducing costs is more compelling, and may help propagate the technique among small-scale miners. Conclusions. Scientific research should continue in order to further establish the uses and limitations of the borax method.

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