Abstract: Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate. A new acid leaching–flotation process for fluorite is proposed in this work. This innovative process raised the fluorite’s grade to 97.26wt% while producing nanoscale calcium carbonate from its leachate, which contained plenty of calcium ions. On the production of nanoscale calcium carbonate, the impacts of concentration, temperature, and titration rate were examined. By modifying the process conditions and utilizing crystal conditioning agents, calcite-type and amorphous calcium carbonates with corresponding particle sizes of 1.823 and 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 compared with the 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, thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.