chemistry of gold extraction using cyanide pdf and ppt

chemistry of gold extraction using cyanide pdf and ppt

  • Extraction of gold using cyanide NZQA

    Extraction of gold using cyanide Gold is found in very low concentrations in the ore from which it is mined To collect the gold from the ore it needs to be separated from the other minerals in the ore To do this the gold needs to be made into a soluble form so that it can be separated from the other minerals as gold is insoluble To make gold soluble sodium cyanide (NaCN) isTHE CHEMISTRY OF THE EXTRACTION OF GOLD Cu(CN); and Cu(CN)! The insoluble gold cyanide compound AuCN precipitates from acidic solutions of aurocyanide ions as follows: Au(CN); + H+ = AuCN + HCN (152) This reaction takes place readily in strongly acidic solution and slowly in weak acid solutions (pH 2 to 3)The Chemistry of the Extraction of Gold SAIMM

  • Extraction of gold using cyanide NZQA

    Exemplar for internal assessment resource Chemistry for Achievement Standard 91389 © NZQA 2015 Extraction of gold using cyanide Gold is found in very low concentrations in the ore from which it is mined To collect the gold from the ore it needs to be separated from the other minerals in the ore To do this the goldFigure 7 Effect of cyanide concentration on gold conversion32 Figure 8 Effect of cyanide concentration on leaching Preleaching: pH 112, 8 ppm O 2, 100 g/t Pb(NO 3) 2, 12 h; cyanide: pH 112, 10 ppm O 233 Figure 9 The effect of pH on gold extraction Condition: 20% solid, 06 MPa,MODELING OF GOLD CYANIDATION

  • Extraction of gold using cyanide NZQA

    Exemplar for internal assessment resource Chemistry for Achievement Standard 91389 © NZQA 2015 Extraction of gold using cyanide Gold is a very precious metal, and is very valuable It has been valuable for a long time Gold has a chemical symbol Au It is found in what is called ore Within this golddilute aqueous solution of sodium cyanide, Stream 16, and a recycle stream, Stream 20a, from Unit 400 The resulting slurry, Stream 18, is fed into large mechanically stirred tanks where it is agitated with air Here, leaching occurs, and the gold is transferred from the ore and forms a goldcyanide complex The complex is then sent to Unit 300 asProduction of Gold West Virginia University

  • (PDF) Gold Extraction and Recovery Processes For

    This process involves the dissolution of gold (and of any silver present in soluble form) from the ground ore in a dilute cyanide solution (usually NaCN or KCN) in the presence of lime and oxygen according to the reactions [2,5]: 2Au + 4KCN + O2 + 2H2O = 2KAu(CN)2 + 2KOH + H2O2 2Au + 4KCN + H2O2 = 2KAu(CN)2 + 2KOH Elsner’s equation 4Au + 8CN + O2 + 2H2O → 4Au(CN)2 + 4OH With optimum cyanide concentration (about 005% NaCN), clean goldMuch simpler and less expensive gravity methods are available to recover this gold Cyanidation is used for gold that is distributed finely through a mineral matrix Liberation: Cyanide leaching will only be effective if the cyanide can come in contact with the gold particle For this to happen, the ore should either be sufficiently porous for cyanide to reach the gold, or more usually the ore is crushed and ground to a size at which the surface of the gold is exposed – ie the goldThe Metallurgy of Cyanide Gold Leaching – An

  • Cyanide Leaching Chemistry & Gold Cyanidation

    The reactions that take place during the dissolution of gold in cyanide solutions under normal conditions have been fairly definitely established Most agree that the overall cyanide equation for leaching and cyanidation of gold is as follows: 4 Au + 8 NaCN + O2 + 2 H20 = 4 NaAu(CN)2 + 4 NaOH Cyanide Leaching Chemistrydissolve gold under aerated conditions The dissolution of metallic gold is due to the strong complexing capabilities of c yanide anions combined with the oxidizing properties of the dissolved molecular oxygen Upon dissolution, gold forms the stableREVIEWING THE OPERATION OF GOLD

  • (PDF) Gold Extraction and Recovery Processes For

    Solvent extraction of gold from alkaline cyanide solution was limited due to the lack of a selective extractant Recent developments in solvent extraction using modified amines and alkyl phosphorus esters have been reported to provide for selective gold extraction from alkaline cyanide solution [5]Alkaline sulfurcontaining lixiviants, including thiosulfate, polysulfides, and alkaline sulfide solutions, stand out as a promising class of alternatives to cyanide because of their low toxicity, high efficiency, and strong adaptability In this paper, we summarized the research progress and remaining challenges in gold extraction using these noncyanide reagents[PDF] A review of gold extraction using noncyanide

  • Cyanide Leaching Chemistry & Gold Cyanidation

    Cyanide Leaching Chemistry & Gold Cyanidation The reactions that take place during the dissolution of gold in cyanide solutions under normal conditions have been fairly definitely established Most agree that the overall cyanide equation for leaching and cyanidation of goldAll the hydrometallurgical gold extraction routes utilize a leaching step to produce a goldbearing solution as an intermediate product while the recycling of secondary gold from the recycling of secondary gold from electronic and precious metal scrap using selective and fast dissolution of the precious metal constituentsREVIEWING THE OPERATION OF GOLD

  • Gold SlideShare

    2 PHYSICAL PROPERTIES OF GOLD • Gold is a chemical element with symbol Au and atomic number 79 • In its purest form, it is a bright, slightly reddish yellow, dense, soft, malleable and ductile metal • Chemically, gold is a transition metal and aStudies on the intensive cyanidation of goldbearing gravity concentrate are carried out in a conical type apparatus The process takes place in presence of 15 kg/t and 30 kg/t of an organic acid as an activator varying the sodium cyanide concentration It is shown that the increase of the reagentactivator presence decreases the extraction time and the leaching losses of gold with tails[PDF] INTENSIVE CYANIDATION OF GOLD USING

  • Cyanide Use in Gold Mining Earthworks

    Kyrgyzstan, Kumtor Gold Mine, 1998: A truck carrying 2 tons of sodium cyanide crashed into the Barskoon river, resulting in more than 2,000 people seeking medical care Romania, Aural Gold , 2000 : A tailings dam ruptured, spilling 35 million cubic feet of cyanideDue to the strong affinity of these resins for goldcyanide anions, elution of the loaded precious metals is difficult and a sulphuric acid/thiourea mixture is most commonly used During elution, the negatively charged goldcyanide complex is broken and a positively charged goldthiourea complex is formed, as shown in Reaction 6TECHNICAL PAPER Purolite

  • Spectroelectrochemical studies of the goldelectrolyte

    Department of Chemistry University of Guelph, Guelph, ON, N1G 2W1, Canada Leaching reagent or lixiviant (L) Extraction from solution by electrowinning +! Low cost ! Reasonably simple chemistry! Small consumption " Environmentally friendly thiosulfate > 2500 mg/Kg thiourea 125 mg/Kg cyanide 64 mg/Kg Compound Toxicity in (ORLRATLD50) Table 1The extraction of gold by the cyanidemethod is of great technical importance It is effected by lixiviation with a solution of potassium cyanide, the gold being precipitated either by addition of zinc or electrolytically The process was suggested by Mac Arthur and Forrest in 1385, and is based on the wellknown solubility of gold in potassiumExtraction of Gold

  • Production of Gold West Virginia University

    2 Marsden, John and Iain House, The Chemistry of Gold Extraction, Ellis Horwood Ltd, Chichester, West Sussex, England, 1992 3 Habashi, Fathi Kinetics and Mechanism of Gold and Silver Dissolution in Cyanide Solution Montana College of Mineral Science andDue to the strong affinity of these resins for goldcyanide anions, elution of the loaded precious metals is difficult and a sulphuric acid/thiourea mixture is most commonly used During elution, the negatively charged goldcyanide complex is broken and a positively charged goldthiourea complex is formed, as shown in Reaction 6Scientific Paper Gold Selected Ion Exchance Resin vs

  • New Technology for Recovery of Gold and Silver by

    gold in the host mineral 2 Extraction of gold and silver from the argentopyrite / argentite ore 21 Pressure oxidation / cyanidation chemistry The oxidation of gold and silver is a prerequi site for its dissolution in the alkaline cyanide lixiviant Pyrite along with arsenopyrite, argent opyrite, sphalerite and covellite are the most commonnative gold from goldbearing ores or the dissolution of gold metal during the recycling of electronic and precious metal scrap is performed every day using hazardous chemicals such as sodium cyanide or aqua regia These chemicals represent health and safety risks for workers and a serious threat for the environment However, even if severalA Method for Leaching or Dissolving Gold from Ores or

  • Bottle Roll Testing for Cyanidation of Gold Ores: Problems

    Keywords: Gold, Cyanide, Leaching, Bottle Roll Test, Pregrobbing, Cyanicide 1 Introduction Cyanide leaching of gold is a very common methodology for evaluation of low grade gold ores Despite risks associated with cyanide, the method proved to be highly effective provided that necessary precautions are taken GoldAll the hydrometallurgical gold extraction routes utilize a leaching step to produce a goldbearing solution as an intermediate product while the recycling of secondary gold from the recycling of secondary gold from electronic and precious metal scrap using selective and fast dissolution of the precious metal constituentsREVIEWING THE OPERATION OF GOLD

  • How gold is extracted by Cyanidation Process

    This extraction is done by converting the gold to a watersoluble form The cyanidation process of gold extraction or the use of cyanide is the most common leaching process, used in the extraction of gold from its ores Some countries do not approve of this method of gold extraction because of the poisonous nature of the cyanide Steps toAfrican gold plant These figures are not a standard but reflect the nature of the ore and the design basis for a particular situation The ore is first reduced in size (typically 80% passing 75µm) to ensure that all nonrefractory gold is readily accessible for cyanide leaching There are several variations of comminution circuits used in theThe process design of gold leaching and carboninpulp

  • Cyanide Use in Gold Mining Earthworks

    Kyrgyzstan, Kumtor Gold Mine, 1998: A truck carrying 2 tons of sodium cyanide crashed into the Barskoon river, resulting in more than 2,000 people seeking medical care Romania, Aural Gold , 2000 : A tailings dam ruptured, spilling 35 million cubic feet of cyanideThiosulphate has received much attention as an alternative noncyanide lixiviant for gold recovery over the last three decades In particular, a number of studies have shown that an ammoniacal copper(II)/thiosulphate system offers fast leaching kinetics, but there are difficulties in controlling the complex solution chemistry and there are concerns over the use of ammonia[PDF] Gold dissolution in nonammoniacal

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