Study On The Comprehensive Utilization Of Carbonation Tower Cleaning Water In Hou’s Process

The technical requirement of using a large Hou’ process factory’s carbonizationtower cleaning water in hubei province as raw material to preparate light calciumcarbonate and magnesium ammonium phosphate was studied respectively.Laboratoryanalysis conclusion is as follows:①Through the orthogonal experiment, the influence of various factors on theproduct particle size was determined as follows: reaction temperature＞dropping speed＞stirring speed.The better reaction condition was reaction temperature25℃, droppingspeed3ml/min, stirring speed700r/min.②By optimum condition optimization experiments, the optimum conditions weredetermined as follows: reaction temperature20~30℃,raw material dropping speed3~4ml/min, reaction time35~50min, stirring speed around700r/min. In this condition,the precipitated calcium carbonate average particle diameter was0.76~1.45μm.③Through the analysis of optimum condition process experiment, SEM andXRD.The result Shows that under the best reaction conditions, added the additive op–10as Ca(OH)2solution mass fraction0.1%,the average particle size of precipitated calciumcarbonate was smaller between0.2~0.5μm,narrow distribution and it’s a better particledispersion degree and calcite crystal shape as square, block. Comprehensive utilization1tcleaning water of carbonization tower in Hou’s Process will recycle44.19kg carbonateions, produce73.65kg precipitated calcium carbonate.④Through the test of preliminary reaction conditions and the orthogonalexperimental analysis, to determine the degree of significant effect on the reactionperformance factors was: reaction pH> phosphorus nitrogen mole ratio n (P): n (n)>magnesium nitrogen mole ratio n (Mg): n (n)> reaction temperature. The bettercondition was: reaction pH at10.0, magnesium nitrogen mole ratio n (Mg): n (n) at1.5:1,phosphorus and nitrogen mole ratio n (P): n (n) at1.1:1, reaction temperature25℃.⑤By optimum condition optimization experiments, the optimum reaction conditionwas determined as: pH9.5, adding the magnesium salt MgCl2·6H2O as magnesium nitrogen mole ratio n(Mg): n(N) at1.2:1and that phosphorate salt Na2HPO4·12H2O asphosphorus nitrogen mole ratio n(P): n(N) at1.1:1, reaction temperature is25℃. In thiscondition, ammonia nitrogen utilization rate was97.4%, magnesium utilization ratio was97.8%, phosphorus utilization rate was99.6%.⑥By analysis the results of optimum technological experiments, SEM and XRD,show that increasing the initial concentration of ammonia nitrogen in range will be goodfor reaction was determined under the optimum reaction conditions. The highestammonia nitrogen utilization rate was over97%,as the initial concentration of ammonianitrogen was around7500mg/L. When using the cleaning water of carbonation towerwith initial ammonia nitrogen concentration about5000～7500mg/L in Hou’s Process asa raw material,the sediment was the target product MgNH4PO46H2O,that the nutrientelements in the content of nitrogen, phosphorus, magnesium, magnesium ammoniumphosphate close to standard, the crystal shape was rules, better distribution and clearcrystal as cubic orthogonal structure. Comprehensive utilization1t cleaning water ofcarbonization tower with ammonia nitrogen concentration at7500mg/L in Hou’s Processcan produce magnesium ammonium phosphate about0.1392t, and recovery ammonianitrogen7.29kg.