Flue Gas CO2 Mineralization Using Thermally Activated Serpentine: From Single- to Double-step Carbonation
Abstract This communication explores the carbonation potential of activated serpentine at flue gas conditions. A first series of single-step batch experiments was performed varying the temperature and the slurry density to systematically assess the precipitation regime of the relevant Mg-carbonates and the fate of the Si species in solution. The results suggested that the reaction progress was hindered by a passivating layer of re-precipitated silica, quartz, or carbonates, as well as by equilibrium limitations. Among several strategies that were tested to overcome these limitations, a simple double-step process that is driven by a temperature swing in combination with a low-level CO2 pressure swing is presented. Exploratory experiments are shown that prove the viability of our process, first by applying a discontinuous method, and secondly by implementing a methodology to cycle the liquid phase continuously between a dissolution reactor and a precipitator. In this way, it was possible to produce highly pure Mg-carbonates that may serve various industries.