| Zhaoyuan mining and smelting company used the efficient enrichment technology of sulfur flotation process developed by the Institute of process engineering in the reusing of cyanide residue.The high sulfur concentrate with sulfur content more than 48%was produced,and the sulfuric acid and iron power of iron content more than 63%were also produced.This technology realized the comprehensive utilization of cyanide tailings,reduced waste storage and environmental pollution.But in the whole process,the sulfur flotation would produce 400t wastewater every day,and the contents of copper,lead and zinc and arsenic were 2.1mg/L,1.8mg/L,8.3mg/L and 10.5mg/L,respectively;the sulphuric acid production process also produced 130t wastewater every day,and the copper,lead and zinc content were respectively 22.12mg/L,3.08mg/L,2.62mg/L,while the arsenic content reached 800mg/L,which was far higher than the standard of Shandong Peninsula basin wastewater discharge standard(DB37/676-2007).In addition,arsenic is a kind of metal like elements,and its compounds are toxic substances.Trace arsenic can cause certain damage to the human body,such as the skin,organ carcinogenesis.With the development of social progress and people's health consciousness,the government has issued a series of arsenic pollution control policies,which has aroused widespread concern of the society and the attention of the related enterprises.In this paper,the effects of different concentrations of pollution factors and pH in the two kinds of wastewater were studied.Firstly,a certain amount of lime and ferrous sulfate solution was added in acid wastewater,and adjusted the pH value of the wastewater.The total arsenic in wastewater was reduced to 34.3mg/L after the neutralization.Secondly,the acid wastewater and the flotation wastewater were mixed after neutralizing treatment,which was treated further by the electrochemical method.This study shows that:When the lime milk was added into the acid wastewater(pH<7),the arsenic content decreased.As pH value increased to 12,the arsenic content did not change significantly,and remained stable;When the ferrous sulfate was added into the wastewater,when pH =9(In this paper,the pH value was used to indicate the content of ferrous sulfate),the arsenic content decreased significantly;In the neutralization process,the arsenic content in the neutralization pond decreased gradually as the residence time of aeration reaction increased.But when the residence time was more than 24h,the arsenic content declined slowly;In the electrochemical process,the contents of various pollutants decreased as the current increased,in which Cu,Pb,Zn content began to decline slowly at 1800mA,and the arsenic content began to slow down at 2000mA.At the same time,the substrate consumption rate was accelerated with the increase of current,and the cost increased.Therefore,the control of the electrochemical system current is 2000mA.In addition,the effects of residence time and flocculant on the removal of arsenic were investigated.According to the experimental results,the company's wastewater treatment system was improved.Lime and ferrous sulfate were added to pretreat the acid wastewater.Then the acid wastewater and the flotation water were mixed,and then the electrochemical treatment was further used to treat the waste water.Finally,the treated wastewater was reused or discharged.The contents of copper,lead,zinc and arsenic content in wastewater after purify treatment were reduced to 0.47mg/L,0.40mg/L,0.44mg/L,0.43mg/L,which achieved the comprehensive utilization of waste water from treatment of cyanide tailings,and satisfied the requirements of the Shandong Peninsula watershed discharge standards. |
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