Method and Apparatus for Producing Core-Shell Calcium Hydroxide-Calcium Carbonate Particles

A method of preparing calcium carbonate (CaCO3)-coated calcium hydroxide (Ca(OH)2) particles comprising:

• throttling a liquid carbon dioxide into an exit stream so as to induce a phase change in the liquid carbon dioxide to a mixture of a gaseous carbon dioxide and a solid dry ice;
• introducing calcium hydroxide particles to the exit stream so as to induce heterogeneous nucleation of the calcium hydroxide particles and promote the formation of the dry ice particles around the calcium hydroxide particles;
• and
• sublimating the dry ice particles formed around the calcium hydroxide particles.

A system for producing calcium carbonate (CaCO3)-coated calcium hydroxide (Ca(OH)2) particles comprising:

• a throttle valve for inducing a phase change from a liquid carbon dioxide to a mixture of a gaseous carbon dioxide and a solid dry ice, the throttle valve being operable to discharge the mixture into an insulated hose comprising an exit stream;
• a screw feeder for introducing calcium hydroxide particles to the exit stream, the calcium hydroxide particles being the heterogenoeus nucleation agent for inducing heterogeneous nucleation and promoting dry ice formation around the calcium hydroxide particles;
• and
• a cyclone to receive the mixture from the exit stream and the dry ice covered calcium hydroxide particles, the cyclone to further sublimate the dry ice.