Process Research On Comprehensive Recovery Of Gold, Silver And Copper Of Poly-metallic And Complex Gold Concentrate

At present, gold, silver and copper were extracted from poly-metallic and complex goldconcentrate by roasting-acid leaching-cyanide method, the leaching ratio of gold, silver and copperis general low. The writer did a series of studies on this phenomenon. The effects of additive and itsdosage, roasting atmosphere, roasting temperature, roasting time on extracting rate of gold, silverand copper were investigated. By the thermodynamics calculation data, analyze the actionmechanism of roasting temperature, additive and roasting atmosphere. On the basis of theoptimum roasting condition, we optimize the leaching process condition. The main research resultsfrom experiments are as follows:The analysis of thermodynamics calculation data known that additive, roastingatmosphere and roasting temperature have great influence on the leaching rate of gold, s ilverand copper. According to the ΔG0T-T chart of the relation chemical reactions at differenttemperatures, we know that sodium hydroxide of additive is playing an important part inlowering chance to generate zinc ferrite, copper ferrite, Positive zinc silicate, Positive leadsilicate, Lead silicate which wrapped around gold and silver of roasting pretreatment. Therelationship diagram between oxygen partial pressure and sulfur dioxide partial pressure revealedthat the higher the oxygen pressure was, the larger the stable area of sulfation roasting was, theeasier the sulfation roasting was, and the higher the extracting rate of gold, silver and copper was.Through gold and silver phase analysis, we know that distribution rate of gold encapsulated insilicates of gold concentrate, direct roasting calcine, roasting with sodium hydroxide calcine, directroasting-acid leaching-cyanided residue, roasting with sodium hydroxide-acid leaching-cyanidedresidue were4.45%,4.38%,0.40%,35.30%,5.14%(the content of gold encapsulated in silicateswere1.2g/t,1.43g/t,0.13g/t,2.16g/t,0.18g/t), and distribution rate of silver encapsulated in silicatesof gold concentrate, direct roasting calcine, roasting with sodium hydroxide calcine, directroasting-acid leaching-cyanided residue, roasting with sodium hydroxide-acid leaching-cyanidedresidue were12.28%,37.54%,9.25%,59.14%,24.75%(the content of silver encapsulated insilicates were64.16g/t,202.11g/t,49.50g/t,242.48g/t,24.75g/t). In a word, gold encapsulated insilicates and silver encapsulated in silicates were the main reason which impact the leaching rate ofgold and silver. The gold encapsulated in silicates and silver encapsulated in silicates have reducedsignificantly when roasting with sodium hydroxide, and the leaching rate of gold and silver wereimproved obviously.The optimal roasting conditions were further determined through experiment as follows: rich oxygen atmosphere, roasting temperature of903K, roasting time of3h, sodium hydroxide dosageof4%. Under above all-mentioned roasting conditions, the poly-metallic and complex goldconcentrate calcine treated by acid leaching-cyanide process, sulfuric acid leaching, reaction liquidto solid ratio is5:1, sulfuric acid molar concentration is0.5mol/L, reaction temperature is323K,reaction time is2h and stirring speed is300r/min; cyanided, reaction liquid to solid ratio is5:1, pHvalue of9.5～11.5, sodium cyanide concentration is0.4%, stirring speed is250r/min, reaction timeis72h and reaction temperature of room temperature. And the leaching ratio of gold, silver andcopper were91.89%,75.81%,92.33%.We optimized the leaching process, and the optimal leaching conditions were determined asfollows: sulfuric acid leaching, reaction liquid to solid ratio is4:1, sulfuric acid molar concentrationis1.0mol/L, reaction temperature is363K, reaction time is3h and stirring speed is300r/min;cyanided, reaction liquid to solid ratio is4:1, pH value of10.5(use Ammonium bicarbonateadjusting reaction pH value), sodium cyanide concentration is0.3%, stirring speed is250r/min,reaction time is72h and reaction temperature of room temperature. under above-mentionedconditions, the extracting rate of copper, gold and silver steady achieved at95%,96%and83%respectively. In cyanide residue, the content of gold, silver and copper less than1.6g/t,130g/t,0.2%.