Abstract:

       Using recyclable NH4Cl (ammonium chloride) as medium of CO2 mineral sequestration has become an emerging
technology, while the low ammonium chloride leaching rate of chrysotile turn into a bottleneck restricting the development of this
process. To solve the problem, this study carried on heat-pretreatment to modify the property of chryattile. Results show that heatpretreatment
can efficiently increase the reactivity of Mg2+ leached from chryostile. After heated at 600℃, the leaching effuciency of chryostile reacted with NH4Cl can reach to 55.64%, increasing about 43%, compared to reaction without heating. Heatpretreatment at 600℃ can remove the outer hydroxyl group in the layers of chryostile, and greatly increase the reactive surface area of minerals and reactive mg2+ it concentration, leading to the improvement of reaction rate. But if the roasting temperature was increased above 600℃, the leaching efficiency of chryostile dropped again since the reactive Mg2+ ot content decreases after removing inner hydroxyl group in the layers of chryostile.

Key words: ammonium chloride, chrysotile, heat-pretreatment, CO2 mineral sequestration