Preparation of high purity fluorite and nanoscale calcium carbonate from low grade fluorite

Flotation separation of calcite from fluorite is a challenge on low grade fluorite flotation, which limits the recovery and purity of fluorite concentrate. This paper proposed a new acid leaching-flotation process for fluorite. This innovative process raised the fluorite's grade to 97.26% while producing nanoscale calcium carbonate from its leachate, which contained plenty of calcium ions. On the production of nanoscale calcium carbonate, the impacts of solid-liquid ratio, pH, temperature, and titration rate were examined. By modifying the process conditions and utilizing crystal conditioning agents, calcite-type calcium carbonate with a particle size of 1.823 μm and amorphous calcium carbonate with a particle size of 1.511 μm were produced. The influence of the impurity ions Mn²⁺, Mg²⁺, and Fe³⁺ was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system when compared to calcium chloride solution. The combination of the acid leaching-flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources, presenting a novel idea for the effective and clean usage of low-quality fluorite resources with microfine particles embedded.