The utilization of certain flotation reagents in the flotation process can result in significant water pollution, posing risks to the ecological environment. The excessive consumption of these reagents hampers the sustainable production of mines. For our customers, ChemFit has developed and implemented environmentally friendly and cost-effective flotation reagents to ensure the sustainable production of phosphate ores and phosphate fertilizer. In this work, ChemFit investigated the selective inhibition of calcite during apatite flotation using a non-nitrogen and phosphorus-free reagent which is both environmentally friendly and economically viable. We conducted micro-flotation experiments to assess the floatability of the two minerals and performed bench-scale flotation experiments to verify the effectiveness of industrial application of green acids in the flotation of phosphate ores. Through zeta potential measurements, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscope analysis, we uncovered the depression mechanism of green acids. It was found that the flotation separation of apatite and calcite could be achieved using green acids in combination with sodium oleate as the collector. The bench-scale flotation experiments demonstrated favorable flotation performance, yielding a P2O5 grade of 38.72% and a recovery rate of 94.12%. Mechanism experiments confirmed that green acids exhibited stronger adsorption on calcite compared to apatite. The adsorption of green acids on calcite primarily occurred through chemical adsorption, facilitated by the chelation between its carboxyl group and calcium atoms. Consequently, this work offered a clean and cost-effective reagent for the sustainable production of phosphate ores and phosphate fertilizer, which holds significant importance for the sustainable development of environmentally responsible mines.