Research Of Ferrite Stabilization Technology On Heavy Metal Of Slurry

Traditional heavy metal of waste water was removed usually by produced hydroxideprecipitation, then the heavy metal sludge was solidificated in cement. But the cementtreatment likely leads too big body size, has expanded phenomenon, heavy metals will bedissolved again and pollute the environment because that a large number of heavy metalhydroxide react with H+easily and destroy the solidified body if cement solidification bodyexist in acidic environment for a long time. This paper hope reduce heavy metal solid wastepollution in environment through a solidification/stabilization technology for heavy metalsludge stabilization directly, at the same time, heavy metal solid waste form is determinedslurry in order to reduce the technological process and cost savings.Through ferrite stabilization technology on pureed of heavy metal directly stabilization,bivalent heavy metal, trivalent heavy metal and its hybrid simulation slurry stabilization wasstudied with three stabilization methods by addited Fe2+/H2O2, Fe2+/Fe3+, Fe2+/O2, actualheavy metal slurry was studied with Fe2+/Fe3+stabilization method, the stability of heavymetals slurry ferrite stabilization is discussed from two aspects of dissolve and leaching.Research results show that three methods can be directly for the stabilization of heavymetals in simulated slurry, Fe2+/Fe3+is the best stabilization method. Stabilizing effect isgood to actual heavy metal slurry with Fe2+/Fe3+stabilization method, its stabilizationproduct is not easy to dissolve.As oxidation ferrite stabilization technology oxidant, compared with O2, H2O2improvethe the oxidation efficiency, which can effectively reduce the oxidation temperature andshorten oxidation time, provides a more choice for heavy metal slurry direct stabilization.The factor of optimal dosing ratio, dosing quantity, pH value, temperature, reaction time,concentration, aging time, adding the alkali, moisture content and the anion to slurrystabilization effect on the kinds of Ni(OH)2and Cr(OH)3single and composite slurry wasanalysed. The conclusions are as follows.There are best dosing proportions with Fe2+/H2O2and Fe2+/Fe3+. Under the condition ofoptimum dosing ratio, with the increase of iron salt dosing quantity, the stabilization effect ofheavy metals in slurry is better. The stabilization effect is greater impacted, and the ferrite isnot easy to generate under the condition of low temperature and acid. Along with the moisturecontent reduce, stabilization effect is gradually variation, mainly is affected by the qualitativeinfluence; Aging time on stabilizing effect the impact is not big, NaOH, Ca(OH)2and NH4OHthree base material control reaction system pH value, NH4OH and NaOH to Ni stabilization,Ca(OH)2against Ni stabilization; Reaction system in anion is Cl-and when NO3-to Nistabilization, SO42-against Ni stabilization. For the Ni(OH)2slurry, under the best conditions that Fe2+：Fe3+=1:7, Fe2+:H2O2=4:3, pHvalue of9, the reaction temperature is70℃, reaction time is1h, iron dosing quantity for themole ratio is Fe:Ni=10:1, the dissolving rate of Ni2+is27.13%,20.57%and60.04%respectively when three kinds of methods Fe2+/H2O2Fe2+/Fe3+and Fe2+/O2acting on theNi(OH)2thick slurry which moisture content is99.8%, concentration is0.01mol/L andvolume is250ml.For the Cr(OH)3slurry, under the best conditions that Fe2+：Fe3+=1:5, Fe2+:H2O2=5:2, pHvalue of9, the reaction temperature is70℃, reaction time is1h, iron dosing quantity for themole ratio is Fe:Ni=10:1, the dissolving rate of Cr3+is16.61%,13.83%and11.57%respectively when three kinds of methods Fe2+/H2O2Fe2+/Fe3+and Fe2+/O2acting on theCr(OH)3thick slurry which moisture content is99.8%, concentration is0.01mol/L andvolume is250ml.For the Ni(OH)2and Cr(OH)3composite slurry, under the best conditions that Fe2+：Fe3+=1:5, Fe2+:H2O2=5:2, pH value of9, the reaction temperature is70℃, reaction time is1h,iron dosing quantity for the mole ratio is Fe:Ni=10:1, the dissolving rate of Cr3+is18.22%,17.68%and10.02%%, the dissolving rate of Ni2+is46.03%,28.94%and22.18%respectively when three kinds of methods Fe2+/H2O2Fe2+/Fe3+and Fe2+/O2acting on thethick slurry which moisture content is99.8%, concentration is0.01mol/L and volume is250ml.For the actual slurry, under the best conditions that Fe2+：Fe3+=1:5, pH value of9, thereaction temperature is75℃, reaction time is1h, iron dosing quantity for the mole ratio isFe:Ni=29:1, the dissolving rate of Cu2+、Ni2+、Zn2+、Cr3+、Cd2+and Pb2+is23.91%,20.45%,35.55%,3.78%and23.71%respectively when the method Fe2+/Fe3+acting on the thick slurrywhich moisture content is99.8%and volume is250ml.XRD, SEM and FTIR, VSM, TG-DTA on stabilizing product were characterized, showthat Fe2+/H2O2, Fe2+/Fe3+two methods formation of ferrite stabilizing product is better, dosingFe2+/H2O2is poorer, after calcining, stabilizing product grain full development and contentwere increased trend; Through the VSM representation, Fe2+/Fe3+stabilizing productmagnetic is stronger; Through the three stabilization method of product settling performanceanalysis, found that the additive Fe2+/Fe3+get stabilizing product settling performance is best,dosing Fe2+/H2O2is the second smallest, and additive Fe2+/O2worst; Thermal analysis showthat the from room temperature to1200℃heating process found no apparent heat absorption,heat release change, the whole process of weightlessness simulation pureed10%, actualpureed is about30%. The actual pureed stabilizing product stability was evaluated. Through the staticimmersion solution experiments, research the leaching time, pH value, vibration velocity,temperature, etc factors on product stabilization of heavy metals in leaching effect. The resultsshow that, stabilizing product is stable, in addition to part hydroxide form of heavy metals aredissolved out of heavy metal, ferrite basic not dissolve out. Through the downflow circulatingcolumn leaching the systematic study of stabilizing product dynamic leaching characteristics,in the pH value for4and6two mode, heavy metal leaching difference is not very big, and inthe initial period of heavy metal leaching quantity is stable, the follow-up time by the impactis not big, show that stabilizing product is stable. Dynamic leaching and static immersionsolution results coincide.The stabilization product stability was evaluated through the static immersion solutionexperiments, the leaching time, pH value, vibration velocity, temperature on productstabilization of heavy metals in leaching effect was studied. The conclusions are as follows.The leaching of heavy metals in stabilizing product changes little over time but is stronglyinfluenced by pH value, such as heavy metal leaching rate increases significantly in the pH <5. The effect of vibrating velocity on heavy metal leaching rate of stabilizing is not very well,for example, the leaching rate of+and Cu2+, respectively from2.24%and3.92%when thevibration speed was100r/min changed to2.45%and5.62%when the vibration speed was500r/min in, and the vibration speed of500r/min of, which show that under the condition of4h reaction time vibrating velocity had a little influence on leaching of heavy metals. Theleaching rate of Pb2+, Ni2+, Cd2+and Zn2+in the stabilization product increase with theleaching temperature rise, such as the leaching rates changed respectively from13.25%,11.63%,9.35%and8.06%to19.00%,17.14%,17.93%and18.71%as the leachingtemperature raised from20℃to40℃. But the leaching rate of Cr3+and Cu2+in thestabilization product changes little with the leaching temperature rise, such as the leachingrates changed respectively from3.28%and4.73%to3.82%and3.55%as the leachingtemperature raised from20℃to40℃.Through the downflow circulating column leaching the systematic study of stabilizingproduct dynamic leaching characteristics, in the pH value for3.8and6two mode, heavymetal leaching difference is not very big, and in the initial period of heavy metal leachingquantity is stable, the follow-up time by the impact is not big, show that stabilizing product isstable. When the pH value is4, in the initial leaching conditions of the first8h time, theleaching rates of Cu2+, Ni2+, Zn2+, Cr3+, Cd2+and Pb2+in the stabilization product were3.69%,12.15%,6.77%,1.59%,15.87%and11.76%. As the pH value is6, in the initial leachingconditions of the first8h time, the leaching rates of Cu2+, Ni2+, Zn2+, Cr3+, Cd2+and Pb2+in the stabilization product were0.49%,6.76%,2.35%,0.10%,15.97%and12.01%. Dynamicleaching has the same results to static immersion solution.