Sep 29 2015nbsp018332Orgul S Reaction chemistry of gold leaching in thiourea solution for a Turkish gold ore Hydrometallurgy 67 7177 2002 Zhu P et al A new technology for separation and recovery of materials from waste printed circuit boards by dissolving bromine epoxy resins using ionic liquid J Hazard Mater 239 270278 2012
The use of thiourea as an alternative nonpolluting reagent for gold leaching is very well known however the processes of gold recovering from thiourea solutions have received little attention
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Reaction kinetics of gold dissolution in acid ph 12 thiourea solutions using ferric sulfate as the oxidant were investigated with the rotating disk technique
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This study has shown that gold and silver can be recovered from a complex anode slime containing copper selenium and tellurium but a carefully planned leaching procedure is required to extract the gold with thiourea it is necessary to first remove the copper selenium tellurium and most of the silver from the mixture once these elements are removed the gold and most of the remaining
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After the desorption with thiourea the pregnant solution contained 246 times more gold and 115 times more silver than the initial one and did not concentrate on the other heavy metals the total gold recovery sorption and desorption stages from the real hydrometallurgical chloride solution
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Compared with the highest gold recovery rate of the single tu leaching 922 177 154 which had additional fe3 and na2so3 supplied after prewashing the rate reached 950 177 073 in the two
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This paper considers the use of the yeast saccharomyces cerevisiae as a biosorbent for the recovery of gold from mahd eldahhab gold mine in kingdom of saudi arabia gold is a noble metal which was seldom used in electroplating hydrogenation catalyst etc heterogeneous composition of samples and low concentration offer renewed interest in the selective extraction of gold using various
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In order to find the optimum conditions of gold leaching with the highest rate of extraction gold recovery numerical optimization was carried out using dx software which is demonstrated in figure 7 it was found that the maximum gold recovery could be obtained of approximately 915 with a desirable value of 100 by numerical optimization
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Apr 15 2010nbsp018332the bioadsorption of metal ions using microorganisms is an attractive technology for the recovery of rare metal ions as well as removal of toxic heavy metal ions from aqueous solution in initial attempts microorganisms with the ability to accumulate metal ions were isolated from nature and intracellular accumulation was enhanced by the overproduction of metalbinding proteins in the
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Adsorption of precious metals in acidic aqueous solutions using thiourea modified magnetic magnetite nanoparticle mnptu was examined the mnptu was synthesized characterized and examined as a reusable adsorbent for the recovery of precious metals the adsorption kinetics were well tted with pseudo secondorder equation while the adsorption isotherms were tted with both langmuir and
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Further experiments aimed on the stabilization of ts in solution revealed a gold recovery of up to 989 gold within 48 hours 015 m ammonium thiosulfate 06 m ammonia 002 m cuiisulfate
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The invention relates to the use of a single solvent extraction reagent which greatly simplifies the recovery of platinum palladium and gold from base metalcontaining solutions the recovery of platinum palladium and gold from acidic feed solutions which contain chloride ion is accomplished by first using a substituted 8hydroxyquinoline
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The use of an acidic ferric chloride solution along with simultaneous electrowinning results in a higher weight percentage of gold in the remaining solid residue 96 in this instance copper recovery was high 99 and electrochemical recovery of gold was more efficient as the residues were 25 times more concentrated in gold compared to the
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Used such as in the diehl process5 gold metal is also leached by aerated aqueous solutions of ammonium thiosulfate6 according to the overall reaction scheme given in reaction 2 finally gold metal is dissolved by an aerated solution containing thiourea7 according to the overall reaction 3 however only the cyanidation process
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In the presence of thiourea 022025 molm2 s in alkaline glycinehydrogen peroxide solutions it has been found that gold leach rate from goldsilver 50 ag alloy is about 6 times higher than rate from pure gold and the silver leach rate was 0247 molm2 s
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Jun 29 1993nbsp018332one method of recovering gold from such thiourea solutions involves neutralizing the acidified thiourea solution to a ph of about 65 which results in the precipitation of gold due to ph change however the method is nonselective and uneconomical due to the acid consumption necessary to readjust the solution ph if the thiourea is to be recycled
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Microbial recovery of petroleum by the conventional technique used in the oil fields approximately onethird of the oil can be recovered however the oil recovery can be enhanced by using solvents and surfactants certain polymers produced by microorganisms eg xanthan gum when added to oil wells are capable of increasing oil recovery
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Gold was selectively recovered with the use of minix while effective recovery of gold platinum and palladium over the base metals copper and iron was achieved with amberlite pwa5 successful elution of these metal cyanides was possible from both minix and amberlite pwa5 using a 2m potassium thiocyanate solution at ambient temperature
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A process for the hydrometallurgical recovery of gold from goldbearing material comprising the step of treating goldbearing material with an acidic lixiviant solution containing thiourea and ferric ions characterized in that the said solution also includes a complexing agent for ferric ions whereby consumption of thiourea is significantly reduced
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Thirty species of microorganisms 8 bacteria 9 actinomycetes 8 fungi and 5 yeasts were screened for maximal gold accumulation extremely high abilities to accumulate gold from a solution containing hydrogen tetrachloroaurateiii were found in bacterial strains such as escherichia coli and pseudomonas maltophilia most of the actinomycetes fungi and yeasts had lower ability to
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Carbon adsorption was considered as the most adequate method for recovery of silver from thiourea leach solutions for this reason it was decided to examine the characteristics of adsorption of silver on activated carbon coconut hard shell activated carbon was used for this study experimental the carbon coconut hard shell was pulverized and dry seived into monosized fractions in the range
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Chapter 4 the recovery of bisthiourea gold perchlorate using solvent impregnated resins 41 preparation of gold solutions for recovery from solution81 42 analysis of gold in solution 83 43 initial tests on the recovery of gold by the resins85
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A method is provided for recovering gold and silver from precious metal bearing materials including ores leaching residues flue dust electronic scrap jewelry scrap etc in the method the gold and silver are extracted from the precious metal bearing materials with a thiourea solution to form a thiourea leach and the thiourea leach is contacted with carbon to adsorb the gold and silver
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Utilized for the removal and recovery of goldiii from aqueous solution therefore the development of a new recovery method using alfalfa biomass to collect goldiii from industrial waste sources might not only reduce the risk of hazardous chemical use but it may also be a more costeffective method as well
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From the loaded resin is studied using acidic thiourea solutions the final recovery from the eluates is accomplished by the use of an alkaline borohydride solution experimental the ion exchange resin lewatit mp64 fluka was used to adsorb gold iii from hydrochloric acid solutions lewatit mp64 is a macroporous mediumbasic anion exchange
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Logical processes recovery of ionic gold from dilute solutions usually involves either precipitation by zinc dust carbon adsorption solvent extraction or ion exchange resins all of these are of low selectivity and comparatively expensive 6 7 chemical methods for the recovery of gold from ores include cyanidation and thiourea
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Nov 09 2015nbsp018332gold from solution i run high iron content ore with thiosulfate the only time there is ever a smell of rotten eggs is after the addition of sulfide as the reductant even then if you havent process for thiourea and thiosulphate leaching post by barren realms 007 187 december 6th 2011 831 am
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Oct 20 2009nbsp018332while the role of microorganisms as main drivers of metal mobility and mineral formation under earth surface conditions is now widely accepted the formation of secondary gold au is commonly attributed to abiotic processes here we report that the biomineralization of au nanoparticles in the metallophillic bacterium cupriavidus metallidurans ch34 is the result of auregulated gene
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A ferric chloride fecl3 preleach at 40 deg c in 6 h extracted about 50 pct of the zinc and formed insoluble silver and lead chlorides subsequent acid thiourea leaching for 1 to 3 h at 40 deg c extracted about 85 pct of the gold and silver lead chloride was solubilized from the remaining residue with nacl brine solution at 55 deg c in 1 h
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Jul 01 1990nbsp018332use the most common uses for thiourea have been for the production of thiourea dioxide 30 in leaching of gold and silver ores 25 in diazo papers blueprint papers 15 and as a catalyst in the synthesis of fumaric acid 10 iarc 2001 it has also been used in the production and modification of synthetic resins other uses of
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Gold uptake by microorganisms fungi and higher plants biomining processes are llsed successfully on a commercial scale for the recovery of gold and other metals and are based on the activity of obligate chemoautolithotrophic bacteria that use iron or sulfur as their energy source and grow in
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