Research On Treatment And Reuse Technic Of Phosphorite Processing Wastewater

Phosphorite resources are abundant in our country, but most are poor quality collophanite. So the process of floatation needs not only high grinding fineness but also quantity of reagent consumption. Because of the action, the composition of the flotation wastewater is very complex. If the wastewater is directly poured into natural water without any measures to deal with, the environment of mining surrounding area would be polluted and it is also a big waste of water recourse.In this paper, the overflow wastewater and tailings wastewater taken from a certain phosphorite plant in Hubei were used as study object. On the basis of experimental determination of harmful substances by analyzing the effect of backwater on the direct flotation process of phophate and phosphorite wastewater quality, the author proposed a segregated treatment, that is, respectively adopting coagulation-precipitation procedure to treat the overflow wastewater and hydroxide precipitate procedure to treat the tailing wastewater. After treatment, the effluent of coagulation-precipitation could meet discharge standard, and the effluent of hydroxide precipitation could be possiblly reused as flotation water. Finally, the concentrate grade and recovery was evaluated.The results showed that the Ca2+, Mn+, SO42-, PO43-, etc. contained in the backwater produced a significant effect on direct flotation process of phosphorite, and they were backwater to control the concentration of 100mg/L,25mg/L, 1g/L, 10mg/L or less.The combined treatment process of "lime milk+PAM" is adopted to treat the overflow wastewater, under the optimum conditions, the removal rate of phosphorus in wastewater up to 99.85%, while the removal rate of CODCr and SS were 81.2%and 92.6%, respectively. The quality of the effluent after treatment reached national class-I standard for the "Integrated Wastewater Discharge Standard".The combined treatment process of "lime milk+CaCl2+PAC+PAM" is adopted to treat the sulfate in overflow wastewater, on the basis of single faceor influential experiment, and by orthogonal experiment determine the optimum conditions, the removal rate of sulfate in wastewater up to over 70%, but can't meet the requirements of backwater quality.On the basis of the effect of reuse is not good after dephosphorization in the tailings wastewater, combined with the effect of backwater quality on direct flotation process of phosphorite, analysis showed that Mn+is the key factor for effecting tailings wastewater reuse, so determine using hydroxide precipitate method to remove Mn+in the tailings wastewater. Under the optimum conditions, the removal rate of Mn+in wastewater up to over 83%. After the tailings wastewater treated by hydroxide precipitate method, the effluent not only meet the requirements of backwater quality, but also can reduce the dose of Na2CO3 in the flotation. Thus reduce the beneficiation cost, create economic benefits for enterprises, but also create social benefits.