Experimental Study On Treatment Of Phosphate Ore Dressing Wastewater By Coagulation Sedimentation Process And Its Reuse

Phosphate ore is widely distributed in Guizhou province. Phosphate ore flotation process produces large amounts of wastewater which contains a lot of flotation residue chemicals and minerals dissolved inorganic ions. If waste water is directly discharged into the river, it will pollute the nearby, which is harmful to environment and human health. In the consideration of environmental protection and water resources increasingly exhausted reality, flotation wastewater recycling is particularly important.In this paper, on the analysis of the Guizhou phosphorus ore dressing plant of thickener overflow water(flotation concentrate wastewater) and tailings tailing water of Ca2+, Mg2+, SO42-, TP and CODMn concentration, the concentration of simulated wastewater is prepared. The effect of water and simulated wastewater on the flotation efficiency was studied. The simulated flotation wastewater is treated by coagulation sedimentation process. Then the appropriate treatment process was determined. The plant wastewater was treated by the determined treatment process.The effect of water reuse after treatment was evaluated.The useful minerals in test phosphate rock is fluorapatite, and the main gangue mineral is dolomite and quartz. Ore grade of P2O5, Mg O, Si O2, and R2O3 was respectively 24.05 %, 6.11 %, 8.16 %, and 1.57 %. So it belongs to the middle-low grade calcium magnesium phosphate ore. This test adopted the "one roughing-one cleaning" flotation flowsheet and FAS as collector, acid wastewater WST as anti flotation p H adjusting agent and inhibitor. The grinding fineness of-0.074 mm content was 77.18 %. Dosage of roughing WST and FAS was 250 kg/t and 1.6 kg/t. Selection of WST and FAS dosage was respectively 75 kg/t and 0.4 kg/t. Dosage of surface active agent was 15 %. On the basis of these conditions to obtain concentrate grade of P2O5 was 31.28 %. P2O5 recovery rate was 91.35 %. The grade of Mg O was 1.04 %. Concentrate grade were reduced to 28.88 % and 29.34 % on the condition of simulated concentrate and tailing waste water directly reused. And the plant flotation concentrate and tailing waste water was directly reused, the concentrate grade was reduced to 27.86 % and 29.56 % respectively.The test was based on Ca O and Na2CO3, and adding different coagulants. Combined with the flotation effect of reuse water after treatment, the appropriate treatment process was determined for “Ca O+Na2CO3+PAC+PAM”. In the simulated concentrate wastewater treatment, the Ca O, Na2CO3, PAC and PAM dosage was respectively 1400 mg/L, 2000 mg/L, 1400 mg/L and 10 mg/L. In wastewater the SO42-, TP, Ca2+, Mg2+ and CODMn removal rate was respectively 30.60 %, 97.54 %, 92.74 %, 82.15 % and 76.88 %. After the treatment the wastewater was used, then the concentrate P2O5 grade was 30.65 %, P2O5 recovery rate was 91.89 %, and the Mg O grade was 1.37 %. The simulated tailing wastewater was tested to determine the Ca O, Na2CO3, PAC and PAM dosage of 1200 mg/L, 1400 mg/L, 1200 mg/L and 6 mg/L respectively. Under these conditions, the removal rate of SO42-, TP, Ca2+, Mg2+ and CODMn in wastewater reached 36.09 %, 93.06 %, 88.99 %, 78.77 % and 88.82 %. The treated wastewater was used for P2O5 flotation test, concentrate P2O5 grade and recovery rate was respectively 30.73 % and 92.56 %, grade of Mg O was 1.24 %. The plant wastewater was treated by determined treatment process, the concentrate wastewater was reused after treatment, and the concentrate P2O5 grade was 30.54 %, P2O5 recovery rate was 92.08 %, and the Mg O grade was 1.47 %. The treated plant tailing wastewater was reused, then the concentrate P2O5 grade and recovery rate was 30.67 % and 91.28 % respectively, the Mg O grade was 1.44 %. Tests show that the wastewater can be recycled after treatment.It was observed in floc scanning electron microscope photos that spherical flocs particles together due to polymer blending agent adsorption and bridging role, forming a loose network like aggregates. Energy spectrum analysis showed the peak of Ca, Mg, P, S, C and other elements of the floc surface, which indicated that the floc settling eliminated impurities in water.