The Synthesis Of Two Small-Molecule Organic Depressants And Its Depressing Mechanisms

Nonferrous metals are essential to the national interest and people’s livelihood, and can be used in many fields, such as industry and agriculture fields. With the development of economy, the mineral resources contained copper and lead are extensively exploited, caused the ore grade is getting lower and lower, and the number of refractory ores is increasing. Because of the similar floatability and fine dissemination size of copper-lead sulfide ores and increasingly importance on the environmental protection and energy consumption, it is imperative to develop the high performance, low toxicity and low cost depressant of copper-lead sulfide ores. According to the actual situation, small molecule organic depressants sodium 2,3-dihydroxypropyl dithiocarbonate (SGX) and O, O-bis(2,3-dihydroxypropyl) dithiophosphate (DHDTP) were synthesized in this study. The separation of chalcopyrite and galena were investigated with SGX or DHDTP as depressant based on the single mineral’s and the artificially mixed samples’flotation tests. Zeta potential, infrared spectrum, adsorption, TOF-SIMS measurements and the calculation results of depression characteristics parameters and molecular dynamics simulation were performed to study the interaction between depressants and minerals.The flotation tests of single minerals were shown that SGX had a certain activation on chalcopyrite, while had strong depression on galena in the range of pH 4-12. DHDTP had slight depression on chalcopyrite in the whole pH range, while had strong depression on galena in the range of pH 4-10, that is to say two reagents (DHDTP and SGX) had high selectivity on chalcopyrite and galena in a relatively wide pH range. With the increase of reagent dosage, SGX activated slightly on chalcopyrite, while depressed galena more and more strongly. DHDTP had slight depression on chalcopyrite, while had increasing depression on galena. The depression of SGX or DHDTP on chalcopyrite and galena was equivalent with that of K2Cr2O7.The flotation tests of artificially mixed samples were found that SGX had better separation of artificially mixed samples when diethyl dithiocarbamate was used as collector than ammonium dibutyl dithiophosphate; while DHDTP had better separation by ammonium dibutyl dithiophosphate than diethyl dithiocarbamate. The separation of artificially mixed samples by SGX or DHDTP were better than K2Cr2O7, indicating that two reagents were effective depressants of galena.Zeta potential and infrared spectrum analyses were indicated that there were hydrogen bonding and electrostatic force interaction between reagents (DHDTP and SGX) and chalcopyrite; while were chemisorption, hydrogen bonding and electrostatic force interaction between reagents and galena, namely the interaction capacity between reagents and galena was stronger than that between reagents and chalcopyrite, and this was proved by the results of flotation tests.Adsorption and TOF-SIMS measurements were shown that SGX and DHDTP had more adsorption on galena than chalcopyrite, and this was also revealed the internal cause that two depressants had stronger depression capacity on galena than chalcopyrite.The calculation results of electronegativity of groups, hydrophilic-hydrophobic index i and HLB were signified that the electronegativity difference between polar groups of reagents (DHDTP and SGX) and Pb was greater than that between reagents and Cu, this meaned that two depressants adsorbed more easily on galena than chalcopyrite.The results of simulation were manifested that the main mode of interaction between two depressants (DHDTP and SGX) and chalcopyrite was two S atoms of reagent molecule were interacted with Cu, Pb atoms of the mineral surface, and the interaction energy between mineral and depressants was greater than that between mineral and collectors (ammonium dibutyl dithiophosphate and diethyl dithiocarbamate), indicating that depressants had weaker adsorption capacity on chalcopyrite than collectors. The main mode of interaction between two depressants and galena was the single bond S atom of reagent molecule was interacted with Pb atom of the mineral surface, and the interaction energy between mineral and depressants was smaller than that between mineral and collectors, indicating that depressants adsorbed more easily on galena than collectors. The results of simulation and the calculation results of depression characteristics parameters can corroborate each other, and explain the results of flotation tests theoretically.