| The mine water containing fluorine not only affects the comprehensive utilization of mine water,but also does some harm to the surrounding water environment.In this paper,the effects of coagulation,adsorption and electro-flocculation on defluorination of mine drainage were studied.The test process took the removal of fluoride ions as the main testing index and turbidity as the secondary testing index,the single factor test,orthogonal test,and response surface test were used to study the influence of various factors on the test effect.The defluorination technology scheme of mine drainage was given,and the comparative analysis and research were carried out.The research results are as follows:(1)The coagulation test results showed that,when fluoride ion removal rate was the main indicator,the influence of the four factors in the coagulation process was ranked as pH,flocculation time,coagulation aid and coagulation agent.In the coagulation orthogonal test,the highest removal rate of fluoride ion was 59.43%and the residual fluorine ion concentration was 1.05 mg/L,which cannot reach the surface water environment quality standard(GB 3838-2002)Ⅲ standards(CF-≤1mg/L).But the removal effect of coagulation test on turbidity was better,the removal rate can reach more than 98%.Therefore,the method of coagulation can not effectively remove the fluoride ion from mine water.(2)The fluoride ions of the flocculated effluent were further treated by adsorption test.The results showed that the significant factor of fluoride removal effect was pH>time>temperature>adsorbent.The optimal solution was:the adsorbent was 5g hydroxyapatite powder,the pH was 4,the adsorption temperature was 25℃,and the adsorption time was 90min.In adsorption of orthogonal experiment,the residual fluorine ion concentration was 0.35～0.79mg/L,which can reach the surface water environment quality standard(GB 3838-2002)Ⅲ standards(CF-≤1mg/L)or less.The study on the treatment of fluorinated mine water by modified raw coal powder showed that the adsorption effect of R2 on fluorine ion was better than that of R1,with the highest adsorption capacity of 0.269mg/g and removal rate of 91.82%.In the adsorption of fluoride ions in mine water,the adsorption process of modified raw pulverized coal R and R2 was more in line with quasi-secondary kinetics.Therefore,the coagulation-adsorption method can effectively remove turbidity and fluoride ions in mine water containing fluorine.(3)When the response value of electro-flocculation was fluoride ion concentration,Al-Al plate was selected and the electro-flocculation times was 40 min,the results showed that the significance order of the three factors in the electro-flocculation reaction process was pH>interelectrode distance>current density,and the interaction between plate spacing and pH was significant.Best running condition was current of 0.75 A,current density of 3.22mA/cm2,interelectrode distance of 4.88 cm,pH of 5.09,simulation of fluorine ion removal rate was 93.95%.In the experimental study of fluoride removal by electro-flocculation,the kinetic characteristics generally accord with the first-order kinetics.In the process of electro-flocculation response surface test,the average removal rate of fluoride ion was 88.52%.The highest removal rate was 92.72%in this test and the lowest fluorine ion concentration was 0.19mg/L,which can reach the surface water environment quality standard(GB 3838-2002)Ⅲ standards(CF-≤1mg/L).For the removal effect of turbidity,the highest removal rate was 97.73%,and the turbidity was 40.1NTU.Therefore,in order to effectively remove turbidity and fluoride ions in fluorine-bearing mines,it is recommended to adopt coagulation-electric flocculation method.To sum up,in the treatment of fluorinated mine water,when the suspended matter content was low,adsorption method or electro-flocculation method can be used,and the removal effect of electro-flocculation method was better than that of adsorption method.When the content of suspended matter was high,coagulation-adsorption method or coagulation-electro flocculation method can be used.Figure[48]table[24]reference[94]... |
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