| In China,the proved tungsten ore is mainly scheelite,which accounts for two thirds of the national tungsten reserves.Ore dressing wastewater of Scheelite is usually discharged in large amount,and contains complicated components.It features high content of suspended solids?SS?and toxic and harmful heavy metal pollutants with low concentration.At present,there is limited research on the treatment of tungsten ore processing wastewater,and there is no satisfactory engineering case in treating it systematically.Therefore,this paper attempts to address this problem.Based on the aforesaid features of tungsten ore processing wastewater,this design scheme is put forward through water quality analysis and technical process selection,and is realized through a treatment project for overflowing wastewater of a tailings reservoir.After debugging,the treatment effect is analyzed.To summarize the demerits of this design,this paper comes up with some improvement suggestions.The main conclusions of this paper are as follows:?1?The designed wastewater treatment capacity in this project is 14400 m3/d,i.e.,Q=600 m3/h,adopting a treatment process of“gyrate sedimentation basin+collecting tank+coagulation reaction pool+oblique tube sedimentation basin+pH value callback in clear pool”.And here are 6 crucial points:1)The grit chamber adopts vortex grit chamber,with a semi-aboveground steel concretestructure and a size of D×H=3050×3100 mm.Besides,its irrigation channel B1=610mm,outlet channel B2=1200 mm.And a sand pump and a water separator are used toremove sand from pools.2)The collecting tank adopts a semi-aboveground steel concrete structure,and a size ofL×B×H=15000×14000×3800 mm.The effective depth h=1.8 m,and the residence timeHRT=30 min.And the water decanter with unpowered constant flow buoy is adopted.3)The coagulation reaction pool adopts a semi-aboveground steel concrete structure anda size of L×B×H=11250×6000×4000 mm.The effective depth he=3.7 m,and theresidence time HRT=23 min.4)The sedimentation tank adopts an inclined tube sedimentation tank and asemi-aboveground steel concrete structure,as well as a size ofL×B×H=5500×5500×6800 mm.The surface load q'=5m3/?m2·h?,and the residencetime HRT=22 min.Besides,its effective sludge bucket volume Ve=66.4 m3.5)The sludge concentration pool adopts a semi-aboveground steel concrete structure anda size of D×H=7000×5000 mm.The effective depth h=3.6 m,and the sludge bucketangle is 55°.6)The clear water reservoirs also adopts a semi-above ground steel concrete structureand a size of L×B×H=8000×4000×4200 mm,with an effective depth h=3.8 m.?2?The total investment in this project total investment is roughly 4.7251 million yuan.After completion,the costs of running this project may include electricity?1373 yuan/d?,agent fee(6185 yuan/d,cost of labor?266 yuan/d?,and engineering unit processing cost?0.453yuan/m3?.?3?The discharge of this project is treated according to level A of Integrated Wastewater Discharge Standard?GB8978-1996?.Through the commissioning and effects analysis,the commissioning results show that the treated wastewater can keep to the standard constantly.For instance,the concentration of SS effluent was stabilized at 47.2 mg/L,and the removal rate was basically stable at 82%.The water concentration of CODCr effluent was basically stabilized at 41.47 mg/L,and the removal rate was 75.6%.The concentration of the As effluent was stabilized at about 0.065 mg/L,and the removal rate is up to 88.6%.The concentration of Pb effluent is 0.034 mg/L,and its removal rate is as high as 97.2%.Besides,it was found that that the concentration of Zn effluent was essentially stabilized at 0.059 mg/L,and removal rate is as high as 97.2%.And no Cd is detected both in inflow and effluent.?4?The general layout of this project and the layout of the elevation layout should be designed based on the gravity flow of waste water to save a lot of energy.A unique design of unpowered constant-current decanter,with uniform water volume,is used to optimize water intake conditions.Sludge from wastewater treatment can be discharged into the tailings reservoir after being treated by the sludge concentration pool,and so there is no secondary sludge pollution.. |
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