Solid-liquid separation of ultrafine Calcium carbonate (CaCO₃) suspensions by using therm-compression filtration technology

School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai 201209, China

^a Corresponding author: xlli@sspu.edu.cn

Abstract

The ultrafine CaCO₃ was usually produced by wet chemical synthesis technique currently. The solid-liquid separation techniques of mechanical filtration and two-stage thermal drying were needed to separate the ultrafine powder from the CaCO₃ slurry. A new technology of thermo-compression filtration was taken to dispose the ultrafine CaCO₃ suspensions for purpose of simplifying the traditional producing technique in this paper. The thermo-compression filtration not only combined the process of mechanical filtration and thermal drying on one single filter press, but also saved energy because of its non-phase-change thermo-compression drying characteristic. The external heat energy was used to offer assistant thermo-motive, but not to vaporize all of the moisture in the saturated cake. The experimental results indicated that the thermo-compression filtration was much more effective than mechanical filtration or thermal drying respectively. The moisture content of filter cake after thermo-compression drying was about 18.75%~21.89%, much lower than that after mechanical filtration, about 25.5%~28.5%. Furthermore, to keep a relative higher temperature of drying plates when mechanical filtration process was an available method to obtain the product with lower moisture content, but use a minimum working time.