The effect of CuO addition on the sintering of lime

The sintering of lime was carried out with 1-4 wt.% CuO in the temperature range 1500-1650 degreesC. A double calcination process was adopted in the study. The result showed that without additive the densification was 88% and with additive it maximised to 93% of the theoretical value at 1550 degreesC with 1 wt. % CuO. The density decreased due to the presence of large closed pores with a higher percentage of CuO. Hydration resistance was measured at 50 degreesC in 95% relative humidity through the weight gain after 3 h. Addition of CuO up to 2 wt.% improved the hydration resistance, but it was not significantly high in comparison to that of 1 wt. % CuO. The use of a higher level of CuO in lime did not show any further improvement in hydration resistance. The CaO forms a low melting compound (2CaO.CuO) with CuO which helps liquid phase sintering of lime. When the liquid content increased in the sinterred lime,grain growth takes place simultaneously along with pore growth. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved