Study On The Treatment Of Cyanide Wastewater From Silver Mine In Hubei Province

The cyanide waste water of silver mine were mainly containing cyanide and heavy metals. Cyanide belongs to toxic substances and heavy metals are a refractory material. From the perspective of ecological environment and biological safety, attaches importance to the effective treatment for silver cyanide wastewater is very necessary.This article explains methods on the basis of summarize the treatment of wastewater containing cyanide and heavy metals. Combining the problems existing in the enterprise bearing cyanide wastewater, explored the method of ferrous sulfate, potassium ferrate combined cyanide wastewater of silver. Analyzed the different conditions on removal efficiency of total cyanide and heavy metal elements in the cyanide wastewater by single factor experiment and orthogonal experimen,at the same time processed back bearing cyanide wastewater used for cyanide leaching. The influence of the following conclusions:(1) Experiment investigated the influence of pH, ferrous sulfate dosing amount, reaction time, flocculant dosing quantity on removal efficiency of total cyanide and heavy metal elements in the cyanide wastewater using ferrous sulfate complexation reaction, the results showed that:a. Considering the removal efficiency of total cyanide and heavy metal elements, determined control when using ferrous sulfate complex first reaction pH was 10, the second reaction pH was 6.5, ferrous sulfate dosage was 12.5 g/L, stirring time was 25 min, polyacrylamide flocculant dosage was 2 mg/L, the total cyanide removal rate was 98.48%, the removal efficiency of heavy metals Cu was 75.55%, the removal efficiency of heavy metals Zn was 65.57%;b. Ferrous sulfate orthogonal experiment results showed that the primary and secondary factors on the impact bearing cyanide wastewater treatment efficiency were: ferrous sulfate dosing quantity > the first step reaction pH > the second step reaction pH > stir time >flocculant dosing quantity. From cyanide removal efficiency analysis of the optimum process conditions of water samples combination were: ferrous sulfate dosing quantity was 12.5 g/L, flocculant dosing quantity was 2 mg/L, the first step reaction pH to 12, the second step reaction pH was 6, the mixing time was 25 min.(2) Experiment investigated the influence of potassium ferrate dosing quantity, oxidation pH value, reaction temperature, oxidation time, flocculation reaction pH and flocculation reaction time on removal efficiency of total cyanide and heavy metal elements in the cyanide wastewater using the ferrous sulfate jointed potassium ferrate, the influence of the results indicated:a. Considered removal efficiency of total cyanide and heavy metal elements, the optimal conditions to deal with wastewater containing cyanide by combined method as: dosage ferrate reached 0.4 g/L, oxidation pH value was 10, oxidation time was 25 min, the reaction temperature was 25℃, flocculation reaction pH was 10, flocculation reaction time was 35 min, the total cyanide removal rate was 99.98%, the removal efficiency of heavy metals Cu was 99.77%, the removal efficiency of heavy metals Zn was 99.36%;b. By ferrous sulfate combined potassium ferrate method of orthogonal experiment to investigate the primary and secondary relations of various factors effecting the cyanide treatment effect: potassium ferrate dosing quantity > oxidation time > oxidation pH > reaction temperature. The joint method of handling cyanide extensions cast potassium optimum technological conditions for: potassium ferrate dosing quantity was 0.4 g/L, oxidation pH value of 10, the reaction temperature was 25℃, oxidation time of 25 min;(3) The wastewater purification treatment after the new process can realize zero discharge of waste water, to solve the huge harm to the environment, the containing cyanide wastewater discharge of degree of cleaner production, and bring good economic benefits and environmental benefits.