Preparation and flotation performance of thionocarbamates

To address the problems of byproduct treatment and pollution in thionocarbamate preparation, four novel processes for preparing O-isopropyl-N-ethyl thionocarbamate (IPETC) were designed, which can coproduce 4-(tert-butyl)benzyl mercaptan (BBSH), sodium benzyl trithiocarbonate (BTTC), sodium O-benzylthioethyl xanthate (SBEX), and benzyl disulfide, respectively. All the products were confirmed via FTIR and mass spectrometry. The composite collector (IPETC and BBSH mass contents were 51% and 41%, respectively) was synthesized via one-pot reaction of sodium isopropyl xanthate, 4-tert-butylbenzylchloride, and ethylamine using tert-butyl alcohol as solvent. The yield of IPETC and BBSH was 95% in the process of coproducing IPETC and BBSH. Specifically, BTTC and IPETC were synthesized via a reaction of sodium isopropyl xanthate, benzyl chloride, ethylamine, carbon disulfide, and sodium hydroxide. The IPETC and BTTC yields were 94% and 95% with a purity of 91% and 82% in the process of coproducing IPETC and BTTC, respectively. Meanwhile, SBEX and IPETC were synthesized via reaction of sodium isopropyl xanthate, 2-chloroethanol, ethylamine, benzyl chloride, carbon disulfide, and sodium hydroxide. The IPETC and SBEX yields were 89% and 93% with a purity of 95% and 91% in the process of coproducing IPETC and SBEX, respectively. Benzyl disulfide and IPETC were synthesized via a reaction of sodium isopropyl xanthate, benzyl chloride, ethylamine, and hydrogen peroxide. The IPETC and benzyl disulfide yields were 93% and 95% with a purity of 92% and 94% in the processof coproducing IPETC and benzyl disulfide, respectively. The flotation response of copper-molybdenum ore independent with IPETC and BBSH collectors and with their mixture was assessed. The flotation results indicate that the composite collector displays a superior collecting capability for copper sulfide ore. Further, the combination of IPETC and BBSH could give rise to a synergistic effect, significantly enhancing the overall flotation performance. The flotation performance of SBEX and BTTC on chalcopyrite and pyrite was also investigated. The flotation results indicate that SBEX and BTTC exhibited better collecting performance than sodium isobutyl xanthate (SIBX), which can replace SIBX for the flotation separation of copper sulfide. FTIR spectra and X-ray photoelectron spectroscopy analyses were conducted. The results indicate that when all three sulfur atoms in BTTC bond to the mineral surface, the hydrophobicity increases when compared to xanthates, wherein oxygen does not bond to the surface. Further, the thioether structure can increase the hydrophobicity of SBEX on the chalcopyrite surface, and SBEX features a higher collecting recovery toward chalcopyrite than SIBX. The results indicate that BTTC and SBEX might bond with copper atoms on the chalcopyrite surface through their sulfur atoms to form BTTC-Cu and SBEX-Cu surface complexes.