Effect of hydroxylated TiO2 on properties of lightweight magnesia aggregates for cement kilns
In order to address the challenges of high load and high thermal conductivity of refractory materi-als in the firing zone of cement rotary kilns,suitable lightweight aggregates for cement kilns were devel-oped.Foaming slurries were first prepared employing light-burned magnesia powder as the raw material,sodium dodecyl benzene sulfonate(SDBS)as the foaming agent,triethanolamine(TEA)as the disper-sant,and TiO2 as the sintering aid.Then MgO foam slurries were prepared,and lightweight magnesia aggregates were successfully synthesized after firing the MgO foam slurries at 1 600 ℃ for 2 h.The effects of the TiO2 addition(0,0.5％,1.0％,1.5％,2.0％,and 2.5％,by mass)on the properties and microstruc-ture of magnesia foam slurries and lightweight magnesia aggregates were investigated.The results show that(1)TiO2 surface hydroxylates;as the TiO2 addition increases,the viscosity of the foam slurries increa-ses,while the surface tension and contact angle decrease;the average size of the bubbles in the slurries ranges from 114.30 to 53.76 μm;(2)TiO2 reacts with CaO in the light-burned magnesia powder,forming CaTiO3;as the TiO2 addition increases,the average grain size of magnesia increases,the amount of interg-ranular pores decreases,the bulk density of the lightweight aggregates increases,and the apparent porosi-ty decreases;(3)the optimum physical properties were achieved when the TiO2 addition was 1.0％.
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