Alkaline sulfur-containing 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 stron...Alkaline sulfur-containing 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.After a brief introduction to the preparation method,the transformation process of various sulfur-containing species in alkaline solutions was discussed.Thereafter,some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were presented from different aspects,including thermodynamics analysis,electrochemical dissolution,and leaching kinetics.Moreover,recent progress in in-situ generation of sulfur-containing anions from gold-bearing sulfide minerals was outlined as well.Gold passivation caused by sulfur species was discussed in particular because it is considered the greatest challenge facing sulfur-containing leaching systems.Alkaline sulfur-containing lixiviants are expected to serve as alternatives in industrial applications of gold extraction,particularly for refractory gold ores containing copper and carbonaceous matter.展开更多
The thermodynamic equilibria and kinetic aspect of gold dissolution in iodine-iodide leaching were studied with emphasis on the effects of pH value and temperature on the system.The results of thermodynamic analysis o...The thermodynamic equilibria and kinetic aspect of gold dissolution in iodine-iodide leaching were studied with emphasis on the effects of pH value and temperature on the system.The results of thermodynamic analysis of iodine in aqueous solution were given and numerous forms of iodine exist mainly in the acid region of pH values.An increase of the potential of the system results in an increase of iodine speciation.The oxidizing potential of the system will increase by the addition of element iodine.The IO^(3-)anions are stable in the potential range from-2.0 to-0.75 V and at pH value greater than 12.1.An increase of the temperature shifts boundaries of existence of various iodine species in the acid region of pH values.Some of them become unstable.The determined values of the diffusion coefficients and the thickness of the diffusion boundary layer,as well as the solvent concentration on the disc surface(14 mg/L) indicate that the process proceeds in the external diffusion region.Thus,while choosing the conditions of leaching from gold-containing materials of different origins of iodide solvents,it is necessary to carry out the process within the acidic region of pH values,where I^-,I_3^- and IO_4^- ions are capable to form complex compounds with metals.展开更多
Butanedionedioxime, a small organic compound with low toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective go...Butanedionedioxime, a small organic compound with low toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective gold lixiviant can be composed of butanedionedioxime (BDM) with many oxidants, especially potassium permanganate; 2)in the leaching system of BDM KMnO 4 the suitable Ox/Lig(ratio of oxidants to gold ligands) range is 0.20～0.50, optimally 0.25～0.45 at the pH range of 7～11; 3) BDM KMnO 4 extraction of gold from an oxide ore is similar to cyanide(cyanide O 2) extraction, but the leaching rate of gold by BDM KMnO 4 is faster than that by cyanide O 2; 4) gold may readily be recovered by carbon adsorption and zinc precipitation.展开更多
Discrimination of different types of sulfur-containing species not only helps us to deeply understand how sulfur affects cellular signaling,but also contribute to the early diagnosis of diseases.However,the current in...Discrimination of different types of sulfur-containing species not only helps us to deeply understand how sulfur affects cellular signaling,but also contribute to the early diagnosis of diseases.However,the current investigation about sulfur-containing species discrimination is mainly concentrated in biothiols,which is relatively limited for practical application.Toward circumventing this limitation,herein,a convenient sensor array consisting of three kinds of Au NCs-Cu2+ for simultaneous and rapid identification of different types of sulfur-containing species is reported.Based on the fingerprint-like fluorescence responses generated by competitive binding between Au NCs-Cu2+ and different sulfurcontaining species,not only ten different types of sulfur-containing species separately but also their binary or ternary randomly selected mixtures can be well discriminated even in human urine and serum samples.It is worth noting that it only takes 2 min to obtain the best response signals for sulfurcontaining species discrimination.Most importantly,serums from cancer patients(such as liver cancer and breast cancer) and healthy people as well as sulfur-oxidizing bacteria(SOB) and sulfur-free bacteria can be both effectively and rapidly identified within 2 min,respectively,making it a promising approach for point-of-care disease diagnostic.展开更多
基金the National Natural Science Foundation of China(No.51574018).
文摘Alkaline sulfur-containing 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.After a brief introduction to the preparation method,the transformation process of various sulfur-containing species in alkaline solutions was discussed.Thereafter,some insights into the mechanism of gold leaching in alkaline sulfur-containing solutions were presented from different aspects,including thermodynamics analysis,electrochemical dissolution,and leaching kinetics.Moreover,recent progress in in-situ generation of sulfur-containing anions from gold-bearing sulfide minerals was outlined as well.Gold passivation caused by sulfur species was discussed in particular because it is considered the greatest challenge facing sulfur-containing leaching systems.Alkaline sulfur-containing lixiviants are expected to serve as alternatives in industrial applications of gold extraction,particularly for refractory gold ores containing copper and carbonaceous matter.
文摘The thermodynamic equilibria and kinetic aspect of gold dissolution in iodine-iodide leaching were studied with emphasis on the effects of pH value and temperature on the system.The results of thermodynamic analysis of iodine in aqueous solution were given and numerous forms of iodine exist mainly in the acid region of pH values.An increase of the potential of the system results in an increase of iodine speciation.The oxidizing potential of the system will increase by the addition of element iodine.The IO^(3-)anions are stable in the potential range from-2.0 to-0.75 V and at pH value greater than 12.1.An increase of the temperature shifts boundaries of existence of various iodine species in the acid region of pH values.Some of them become unstable.The determined values of the diffusion coefficients and the thickness of the diffusion boundary layer,as well as the solvent concentration on the disc surface(14 mg/L) indicate that the process proceeds in the external diffusion region.Thus,while choosing the conditions of leaching from gold-containing materials of different origins of iodide solvents,it is necessary to carry out the process within the acidic region of pH values,where I^-,I_3^- and IO_4^- ions are capable to form complex compounds with metals.
文摘Butanedionedioxime, a small organic compound with low toxicity and good chemical stability, has been proposed as an effective gold ligand in gold extraction. The result of experiment shows that: 1) highly effective gold lixiviant can be composed of butanedionedioxime (BDM) with many oxidants, especially potassium permanganate; 2)in the leaching system of BDM KMnO 4 the suitable Ox/Lig(ratio of oxidants to gold ligands) range is 0.20～0.50, optimally 0.25～0.45 at the pH range of 7～11; 3) BDM KMnO 4 extraction of gold from an oxide ore is similar to cyanide(cyanide O 2) extraction, but the leaching rate of gold by BDM KMnO 4 is faster than that by cyanide O 2; 4) gold may readily be recovered by carbon adsorption and zinc precipitation.
基金support from the National Nature Science Foundation of China(Nos.21675093,21505081 and 21974075)the Natural Science Foundation of Shandong Province of China(No.ZR2019YQ13)+1 种基金the Science and Technology Support Plan for Youth Innovation of Colleges and Universities in Shandong Province(No.2019KJC007)the Taishan Scholar Program of Shandong Province,China(No.ts20110829)。
文摘Discrimination of different types of sulfur-containing species not only helps us to deeply understand how sulfur affects cellular signaling,but also contribute to the early diagnosis of diseases.However,the current investigation about sulfur-containing species discrimination is mainly concentrated in biothiols,which is relatively limited for practical application.Toward circumventing this limitation,herein,a convenient sensor array consisting of three kinds of Au NCs-Cu2+ for simultaneous and rapid identification of different types of sulfur-containing species is reported.Based on the fingerprint-like fluorescence responses generated by competitive binding between Au NCs-Cu2+ and different sulfurcontaining species,not only ten different types of sulfur-containing species separately but also their binary or ternary randomly selected mixtures can be well discriminated even in human urine and serum samples.It is worth noting that it only takes 2 min to obtain the best response signals for sulfurcontaining species discrimination.Most importantly,serums from cancer patients(such as liver cancer and breast cancer) and healthy people as well as sulfur-oxidizing bacteria(SOB) and sulfur-free bacteria can be both effectively and rapidly identified within 2 min,respectively,making it a promising approach for point-of-care disease diagnostic.
