磷酸二氢铵与铅锑氧化物的高温反应行为

Reaction of NH_4H_2PO_4 with Lead and Antimony Oxides at High Temperature

通过磷酸二氢铵与氧化铅及氧化锑所组成的二元混合物的TG/DTA分析,了解混合物的热行为,用XRD表征混合物在选定温度下的煅烧产物。结果表明,当磷酸二氢铵与氧化铅的物质量比为2.5∶3,在750℃下煅烧30min得到Pb2P2O7[空间群P-1(2)]和Pb5P4O15[空间群P21/c(14)]的混晶。而当磷酸二氢铵与氧化锑的物质量比为2.5∶1,在750℃下煅烧30min得到空间群为P21/m(11)的SbPO4晶体。将SbPO4与PbO组成的混合物在850℃下煅烧30min,SbPO4又转变成以Pb14.67Sb1.33(PO4)12[空间群1-43d(220)]为主的混晶,从而表明Pb14.67Sb1.33(PO4)12是一种在高温下比SbPO4更稳定的化合物。因此磷酸二氢铵可作为火法精炼锑的除铅剂。

The thermal behaviors of the mixtures consisting of NH4H2PO4 and PbO or Sb2O3 are investigated by the TG/DTA analysis, and the products obtained from calcining mixture at fixed temperature are characterized by XRD. The results show that a mixture of Pb2P2OT[Space group P-1（2）] and Pb5P4O15[space group P21/c（14）] is obtained in condition of 2.5 ： 3 molar ratio of NH4H2PO4 to PbO, 750℃ for calcining temperature and 30 min for calcining time. Moreover, SbPO4, space group P21/m （11）, is obtained when 2.5：1 molar ratio of NH4H2PO4 to Sb203, 750℃ for calcining temperature and 30 min for calcining time. The SbPO4 is turned into Pb14.67Sbl.33（PO4）12 [space group 1-43d （220）] when mixture of SbPO4 and PbO is calcined at 850℃ for 30min. It shows a fact that Pb14.67Sb1.33（PO4）12 is a kind of more steady compound than SbPO4 at high temperature. Thereby, NH4H2PO4 can be used as a reagent for removing lead in fire refining Antimony.