The Research Of H₂O₂/(Fe²⁺/Fe³⁺) Homogeneous Catalytic Oxidation System In Gold Wastewater Thiocyanate And Cyanide Regeneration

With the application of large scale cyanide leaching process, and gold and silver sulphide ore and the increase of the concentration of the concentrate, people are putting more attention on the study of transformation of sulfur cyanide to cyanide and better removal of the sulfur in the waste water. Through treatment of cyanide waste liquid to reducie the toxicity of wastewater.In this paper, we mainly discuss the apparent kinetics of SCN^- catalytic oxidation in wastewater by Fenton and Fenton- like oxidation system. Comparative analysis on the application of SCN^- in the catalytic oxidation of two different free radical systems. Using Co²⁺、Ni²⁺ as catalyst, catalytic H₂O₂ to produce hydroxyl radical, to explore the effects of various factors on the catalytic oxidation of SCN^- and the exploration of the regeneration of cyanide. The main contents and conclusions of this paper are as follows:（1） Apparent kinetics study on process of SCN^- in the homogeneous catalytic oxidation of gold mine wastewater. The Fenton reaction is composed of Fe²⁺ as catalyst and H₂O₂ as oxidant. And Fe³⁺ as catalyst and H₂O₂ as an oxidant for the Fenton- like reaction. In the range of pH=2.5³, the temperature is controlled at 23℃, The effects of initial concentration of SCN^-, Fe²⁺ and H₂O₂ on the reaction rate of Fenton were investigated. By changing the initial concentration of various substances, the change of the catalytic oxidation of SCN^- reaction system was obtained. The apparent kinetic model was established by fitting the power function equation. Results show, under acidic conditions, the Fenton reaction series is 2.62, and the apparent kinetic equation is expressed as : 87.089.086.05GHW1053.7V-′=. The Fenton- like reaction series is 4.09, and the apparent kinetic equation is expressed as: 51.146.112.17GHW1023.1V-′=.（2） Fenton and Fenton- like oxidation method is using Fe²⁺ catalytic H₂O₂ and Fe³⁺ catalytic H₂O₂ to produce ·OH free radical.and the oxidation method which is using Fe²⁺ activated persulfate（PS） produceSO₄^-· free radical. The process of catalytic oxidation degradation of SCN^- in wastewater was studied. Single factor analysis of the solution pH value, reaction time, reaction temperature and the effect of SCN^- ion concentration, oxidant dosage, catalyst dosage on the removal efficiency of SCN^-. Experimental results show that: compared to the Fenton, and Fenton- like oxidation system, the use of free radical on pH value is more widely. In acidic, neutral and alkaline conditions were able to achieve a certain treatment effect. But Fenton and Fenton- like oxidation reaction rate is fast, in a short period of time it can achieve a certain removal effect. In the system, the oxidation dose and concentration of SCN^- is unchanged. Two systems for the removal rate of SCN^- all decreased with the increase of the mole ratio of the oxidant and the catalyst. With the increase of the molar ratio of SCN^- and oxidant increase. Two systems for the removal rate of SCN^- all increase with the increase of experiment temperature, increase with the extension of reaction time. In general, the oxidation reaction of free radical system is relatively slow than that of free radical system.（3） Using Co²⁺、Ni²⁺ as catalyst, catalytic H₂O₂ to produce hydroxyl radical, degrade the sulfur cyanide in wastewater. Single factor analysis of the solution pH, reaction time, reaction temperature and the SCN^- concentration, oxidant dosage, catalyst dosage on the SCN^- ion removal effect. Analysis can be drawn from the results of the experiment, the removal efficiency of SCN^- was not obvious by using cobalt ion and nickel ion as catalyst. The removal rate is poor, and the amount is more, the raw material is not easy to get, the reaction duration is shorter.（4） Using H₂O₂ as oxidant to change the acid salt of different concentrations, when the concentration of H₂O₂ is fixed, after reaction 1h, using NaOH as absorbent to absorb hydrocyanic acid. It can be seen from the experimental results. although hydrogen peroxide can oxidize some of the salt to cyanide, but the oxidation effect is not very obvious. The production rate of cyanide is low.