| The treatment method and technology of treating fluoride-containing wastewater is an important subject to be studied urgently in the field of environmental protection.In this paper,the fluoride-containing beneficiation wastewater was taken as the research object,the chemical precipitation adsorption composite process was used to treat the simulated fluoride-containing beneficiation wastewater.The influence of different precipitation process conditions on the fluorine removal effect was studied,and the best conditions of this process were determined.The simulated fluoride-containing wastewater after precipitation treatment was further treated by adsorption method,the adsorption characteristics of F-were studied,and the best adsorbent and adsorption process conditions were selected.Taking feldspar fluoride-containing beneficiation wastewater as the object,the process of chemical precipitation adsorption was adopted to treat it under the suitable operation conditions,and it was determined whether the wastewater after treatment met the discharge requirements of the first level standard of integrated wastewater discharge standard?GB 8978-1996?.In this paper,the fluoride-containing ore dressing wastewater was taken as the research object,which was treated by the chemical precipitation adsorption composite process,so that the fluoride-containing ore dressing wastewater could reach the discharge standard,providing reference for the treatment process of fluoride-containing wastewater.The main conclusions were as follows.?1?The defluoridation effects of three precipitants,namely,slaked lime,technical grade calcium chloride,and slaked lime-industrial grade calcium chloride combined medicament on the simulated fluoride-containing wastewater with an initial fluoride concentration of1000 mg·L-11 under different precipitation conditions were studied.The fluoride concentration in the solution could be reduced to about 35 mg·L-11 with the slaked lime prepared from light-burned limestone as a precipitant,about 20 mg·L-11 with industrial grade calcium chloride as precipitation agent,and slaked lime-industrial grade calcium chloride combined medicament as a precipitant could reduce the residual fluoride concentration of the solution to about 25 mg·L-1.Considering the effect and cost of defluoridation,the combination of slaked lime and industrial calcium chloride was used as precipitant.?2?To investigate and analyze the fluoride removal effects of chemical precipitation and induced crystallization precipitation as the pretreatment of simulated fluoride wastewater.The optimal conditions for the treatment of simulated fluoride-containing wastewater by chemical precipitation method were as follows:taking slaked lime-industrial calcium chloride combined agent as precipitant,Ca?OH?2 and the total calcium ratio is 1/2,calcium-fluoride ratio is 0.75 and precipitation reaction time is 30 min.After standing for 30minutes,the residual fluoride ion concentration was about 25 mg·L-1.The best conditions for treating simulated fluoride-containing wastewater by the induced crystallization precipitation method were as follows.Taking slaked lime-industrial calcium chloride combined medicament as the precipitant,add seed fluorite with a particle size of 200-300 mesh,the precipitant composition has a molar ratio of Ca?OH?2 to total calcium of 1/2 and a calcium-fluorine ratio of 0.75,the dosage of seed crystals is 10 g·L-1and the precipitation time is 6 h.After standing for 30 minutes,the residual fluoride ion concentration was about15 mg·L-1.?3?The simulated fluoride-containing wastewater after sedimentation pretreatment was treated by adsorption method with LDHs and MLDHs used as adsorbents to remove fluoride in depth.it was better to choose.The suitable conditions of using LDHs as adsorbent were the concentration of the adsorbent was 1.2 g·L-1,the adsorption pH was 8 and the adsorption time was 12 h at room temperature.After treatment,the F-removal rate of the adsorbent material was more than 90%,and the remaining fluoride ion concentration in the water was1.15 mg·L-1,which met the first level standard for integrated wastewater discharge?GB8978-1996?.Under the same conditions,with MLDHs as adsorbent,the F-concentration of effluent water was 4.1 mg·L-1,and the adsorbent could be separated rapidly by magnetic field.?4?Taking feldspar fluoride-containing beneficiation wastewater as the treatment objects,after adsorption with hydrated lime industrial calcium chloride used as precipitant and200-300 mesh fluorite as crystal seed,and defluoridation with LDHs.The concentration of fluoride in the wastewater was 1.43 mg·L-1,the effluent pH was 7.37,the COD concentration was 26.62 mg·L-1,the total nitrogen concentration was reduced to 10.64mg·L-1,and the total iron concentration was 0.002 mg·L-1,which met the first level discharge standard of national industrial wastewater?GB 8978-1996?. |
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