ADVANCED APPLICATION OF LIME

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1. Conducting coating of CaCO_3Ag coated calcite was obtained by calination of Ag_2CO_3 coated calcite prepared by ion exchange method from AgNO_3 aqueous solution with the suspension of calcite particles. The coating on calcite was most uniform by calcination at 400-500ﾟC of the particles prepared at 40ﾟC,under [AgNO_3]=1.8*10^<-2>M and suspension of calcite=1-4g/1 for 3-6h. The conductivity of Ag coated calcite was measured by Impedance gain-phase analyzer (Solartorn, SI-1253).2. Synthesis of colored CaCO_3(1) Solid solution with transition metal ionThe crystallization of CaCO_3 by co-precipitation from mixed aqueous solution of Ca(NO_3)_2 and Na_2CO_3 homogeneous precipitation using (NH_2)_2CO was investigated in the pressence of Ni^<2+>, Co^<2+>, Mn^<2+> or Fe^<3+> ion. The resulting CaCO_3 was colored slightly with the color of metal ion. The addition of Ni^<2+> and Mn^<2+> made change the lattice constant of calcite particles prepared at 35ﾟC.The lattice parameter of aragonite prepared at 90ﾟC with Mn^<2+> ion addition also changed. These results suggest their substitution for Ca^<2+> ions in CaCO_3.(2) Coating of Ni compound on CaCO_3Ni compound-coated CaCO_3 particles were prepared by heating Ni (NO_3)_2 aqueous solution with the suspension of calcite particles. Calcite was most uniformly coated by NiCO_3・6H_2O and colored light green by the reaction at 70ﾟC,under [Ni (NO_3)_2]=0.01M and suspension of calcite=0.1M for 5h.(3) Coating of CO compound on CaCO_3As coating of Ni compound, Co compound-coated CaCO_3 particles were prepared. The coating was most uniform at 70ﾟC,under [Co (NO_3)_2]=0.001-0.01M,and suspension of calcite=0.1M for 5h. The color of resulting particles were measured by UV seactro photometer (Hitachi Co., U-3300). The color of deposit was blue under [Co (NO_3)_2]=0.001M,and violet under [Co (NO_3)_2]=0.01M.