Study On The Application Of Neutralization Method In The Treatment Of Steel Pickling Waste Liquor

At present,the research on pickling waste liquor is mainly based on comprehensive utilization,however,most of the problems of heavy metals in pickling waste liquid did not considered.For the pickling waste liquid with high heavy metal content is not suitable for direct use,so measures must be taken to remove heavy metals,or the direct disposal.Neutralization method is the main method for the treatment of pickling waste liquid.In the process of neutralization and disposal of pickling waste liquid,these was less research on the selection of chemicals with alkali metal ions,purification efficiency,filter waste pollutant residues problem.In this paper,the pickling waste liquid of steel cord and zinc plant is studied.Acid neutralizing agent selected the most commonly used NaOH,Ca?OH?₂,CaO three kinds of alkaloids.Through the study of the factors such as the sludge yield,filtrate yield,the residual amount of heavy metals in the filtrate and the cost of treatment,the types of alkali and the control parameters were optimized.At the same time,the effect of iron ion valence state on the neutralization effect was also studied.Provided reference for the practical application of pickling waste liquid neutralization and disposal method.?1?For pickling waste liquid of steel cord factory,the best dosage of Ca?OH?₂is 23%,the sludge production is 40% and the filtrate is 37%.Filtrate of zinc,lead,chromium,nickel,iron were 4.32mg/L,0.640mg/L,1.39mg/L,5.88mg/L,25.7mg/L.Filtrate salinity was 36.8%.Sludge still need to dispose of hazardous waste.Heavy metals in the filtrate is not meet the standard,so it can not be discharged directly.The processing costs 1650 yuan/m³.The optimal dosage of NaOH is 19%,and the pH value is 8.73.Under the optimum experimental conditions of two kinds of reagents,the cost of NaOH treatment is 12% higher than that of Ca?OH?₂.The best dosage of CaO is 16%,and pH is 9.16,and processing cost is 13% less than that of Ca?OH?₂.Zn,Pb,Cr,Ni and Fe residue of the filtrate increases by 49%,41%,3.6%,7.8%,33% than that of Ca?OH?₂.?2?For pickling waste liquid of steel cord factory,the best dosage of Ca?OH?₂is 26%,the sludge production is 46% and the filtrate is 34%.Filtrate of zinc,lead,chromium,nickel,iron were 9.19mg/L?1.18mg/L?1.16mg/L?0.767mg/L?4.89mg/L.Filtrate salinity was 46%.Sludge still need to dispose of hazardous waste.Heavy metals in the filtrate is not meet the standard,so it can not be discharged directly.The processing costs 2040 yuan/m³.The best dosage of NaOH is 22%,and the pH value is 8.73.The treatment cost is15% higher than that of Ca?OH?₂.The best dosage of CaO is 18%,and pH is 9.16,and the cost is reduced by 9%,the zinc,chromium,nickel,iron residue rise 24%,17%,13%,29%.?3?In steel cord pickling waste liquid,Ca?OH?₂ dosage is 22%,pH value is8.03,the treatment effect is the best,and the removal rate of nickel,zinc,iron,lead and chromium is 96.4%,99.6%,99.9%,93.4%,97.7%,respectively.Nickel,zinc,iron,chromium residual amount decreased by 83%,50%,61%,12% respectively compared with the former.For galvanizing plant,Ca?OH?₂ dosage is 23%,and the pH value is 7.56,At the same time,the removal rates of nickel,zinc,iron,lead and chromium are 97.7%,99.5%,99.9%,92.9%,96.4%,respectively.In addition to Zn,the rest of the metal residual amount can meet the standard,in which nickel and lead residual amount reduced by 19%,7% compared to the former.To sum up,for the three kinds of alkali,heavy metal sludge production,comprehensive comparison of filtrate yield,residual filtrate and processing cost,Ca?OH?₂ best effect.Increase the valence state of iron ions is conducive to the removal of heavy metal ions in the filtrate,improve the efficiency of more than 50%.