Optimization of Low-Rank Coal Flotation Using Jatropha curcas Biodiesel via Response Surface Methodology

In this study, the focus is on investigating the performance of Jatropha curcas biodiesel as a potentially eco-friendly and non-edible collector for use in the flotation of low-rank coal. Due to its high cost and limited efficiency, using diesel as a collector for treating low-rank coal flotation presents several challenges. To achieve this aim, a systematic approach was adopted, employing a statistical design methodology to develop comprehensive mathematical models for combustible recovery and ash content. These models considered various parameters, including the dosage of the collector and frother, the solid percentage, and the depressant. The test results indicated that both models were statistically significant (p < 0.05). Furthermore, the findings showed that when the collector, frother, solid percent, and depressant were set at 0.5 kg/t and 2.13 kg/t, 0.26 kg/t and 0.214 kg/t, 15.00% and 14.40%, and 0.50 kg/t and 0.51, respectively, the ash content and recovery efficiency were 11.2% and 80.08%, respectively. The results also indicated that the doses of the frother and collector had a greater impact on the response variables than the other factors. In addition, verification experiments were conducted under the ideal conditions specified by the models to assess their validity and sufficiency. The SEM-EDS results confirmed that the concentration of carbon in coal cleaned with Jatropha biodiesel was higher than that cleaned with diesel oil. Furthermore, an FT-IR investigation showed that Jatropha biodiesel was more effective than diesel oil in reducing hydrophilic groups and enhancing hydrophobic groups. The hydrogen bonding between the oxygen-containing groups in Jatropha biodiesel and the surface of low-rank coal was responsible for the improvement in floatability and flotation recovery, which means Jatropha biodiesel, could be utilized as a substitute collector in the flotation of low-rank coal.