The selective flotation separation of apatite from dolomite using carrageenan as an innovative bio-based inhibitor

The direct flotation is highly effective in enhancing the quality of concentrate products and removing the content of magnesium for the beneficiation of middle and low grade phosphate ore. This study introduces carrageenan (CG) as an innovative dolomite inhibitor and assesses its effectiveness through micro-flotation tests with sodium oleate (NaOL) as a collector. At pH 10, the combination of 40 mg/L CG and 4 x 10-4 M NaOL successfully separated dolomite from apatite, the artificially mixed ore tests produced a concentrate assaying 32.23 % P2O5 with 76.44 % P2O5 recovery. Results demonstrate CG's strong inhibition of dolomite while minimally affecting apatite. The interaction mechanisms of CG with apatite and dolomite were investigated through various analyses including ICP-OES tests, zeta potential measurements, FTIR tests, contact angle measurements, XPS analysis, AFM tests, and ToF-SIMS analysis. Findings suggest that CG adsorbs strongly to dolomite surfaces by chemisorption between carboxyl groups and Ca sites, whereas it adsorbs weakly to apatite surfaces by hydrogen bonds between carboxyl and hydroxyl groups with F sites. Thus, CG shows promise as an innovative bio-based inhibitor for separating apatite from dolomite using direct flotation.