Deactivated SCR Catalyst Compounded With Calcium Carbonate And As A Ceramic Emulsion

Deactivated SCR catalysts from coal-fired power plants are large and difficult to treat solid wastes,and making full use of the valuable components in them to realize their materialization is an important step to eliminate their environmental pollution,realize resource utilization and increase economic benefits.Based on the above background and the characteristics of deactivated SCR catalysts,which are mainly composed of titanium dioxide（Ti O₂）carriers,this thesis investigates the preparation of CaCO₃-SCR complexes by liquid-phase mechanical force grinding method,calcination of CaCO₃-SCR complexes by solid-phase method and the preparation of perovskite by CaCO₃-SCR complexes and CaCO₃-SCR catalysts and perovskite as emulsions,respectively,from deactivated SCR catalysts and calcium carbonate（CaCO₃）in coal-fired power plants.CaCO₃-SCR complexes and CaCO₃-SCR complexes as emulsions for the preparation of sanitary ceramic glazes were investigated.The results are also expected to play a positive role in eliminating the radioactive radiation hazards in the glaze layer caused by the use of zirconium silicate（Zr Si O₄）emulsion and the yellowing of the glaze surface caused by the use of a single Ti O₂ as emulsion.The preparation and characterization of CaCO₃-SCR complexes by liquid-phase mechanical force milling and CaCO₃-SCR complexes by solid-phase calcination were investigated.The optimized process conditions for the preparation of CaCO₃-SCR complexes were Ca O/Ti O₂（molar ratio）=1,slurry concentration 20%,pellet ratio 4,and grinding time 2 h.The resulting CaCO₃-SCR complexes were achieved by homogeneous encapsulation of Ti O₂ in SCR on the surface of CaCO₃ particles,CaCO₃ and Ti O₂ through the formation of-Ca-O-Ti-bonds by hydroxyl groups on the surface of the particles.binding.The optimized process conditions for the preparation of chalcocite were calcination temperature of 1000°C and holding time of 2 h.The prepared chalcocite products mainly consisted of chalcocite phase with massive particles with clear contours and size of about 150 nm.The preparation and properties of sanitary ceramic glazes using CaCO₃-SCR complex and chalcocite as emulsifier were investigated.The optimal preparation conditions for CaCO₃-SCR complex were:11%addition to glaze,firing temperature of 1175°C,holding time of 4 h.The resulting glaze had a milky white appearance with L*,a*and b*values of 94.01,-0.75 and 5.68,respectively;the optimal preparation conditions for chalcocite were:9%addition to glaze,firing temperature of 1150°C,holding time of 4 h.The resulting glaze had a white appearance with L*,a*and b*values of 94.01,-0.75 and 5.68,respectively.The best preparation conditions for the use of perovskite are:9%addition ratio in glaze,firing temperature 1150°C,holding time 4 h.The resulting ceramic glaze is white,with L*,a*and b*values of 93.09,-0.76 and 4.98,respectively.Glossiness is comparable,and yellowness value is slightly larger.The emulsion mechanism of CaCO₃-SCR complex and chalcocite as emulsions in the glaze layer of sanitary ceramics was investigated.The phases of the glaze layer of sanitary ceramics using CaCO₃-SCR complex and calixarene as emulsifier were mainly titanite,quartz and amorphous matter,with titanite predominating,and titanite particles were well distributed in the glaze layer and well dispersed.In the glaze layer with CaCO₃-SCR complex as emulsifier,titanite particles are in the form of long columns and wedge-shaped blocks with a particle size of about 0.5-1 mm,while in the glaze layer with perovskite as emulsifier,titanite particles are in the form of short columns with a particle size of about 0.2-0.5 mm.Both ceramic glaze layers are emulsified by titanite precrystallization.