Forecasting of Perspective Flotation Reagents on the Base of Structure Based Virtual Screening
The molecular models of complexes of poorly studied mineral clusters and reagents in developing the principles of evaluation of forecasting in flotation reagent activity have been created and optimized by using Chem Bio 3D and ChemOffice2005 by Cambridge Soft with optimization by MM2. It is proposed to use structure based virtual screening (SBVS) and reduce enormous amount of chemical compounds to a more manageable number for synthesis and screening which could lead to potential flotation candidates. The metal tellurides and arsenic sulfides as poorly explored types of minerals have been investigated. HOMO, SOMO, LUMO and total energies, atomic charges and s, p, d-population were determined for the various compounds. The strategy of prognosis of collector activity evaluation (PCAE) has been proposed as a consistent approach to estimate the interaction between a collector and a mineral cluster to search the analogue of butyl xanthate. The relationship between PCAE and flotability has been established. Our results indicate that the lower PCAE the stronger the interaction between the collector and the mineral cluster. The binary complexes of various reagents on the mineral surface have been studied. It was shown that the lowest magnitude of PCAE was obtained for arsenopyrite with binary mixture of dibutyl dithiophosphoric acid and diethylaminoethyl xanthic acid that indicated the high chemical activity of the combination of reagents. Forecasting of perspective flotation reagents by screening of chemical compounds and theoretical results obtained from research can provide a basis for innovative technology in mineral processing.
Investigation of the effect of N-substituents on performance of thionocarbamates as selective collectors for copper sulfides by ab initio calculations
Abstract Using ab initio methods, we calculated some properties such as the energies and compositions of frontier molecular orbitals and the atomic charges which are related to the reactive behavior of thionocarbamates containing different N -substituent groupings. The results of the calculations indicate that the efficiencies of N -substituent thionocarbamates depend on the investigated parameters, and the N -substituent groupings have significant effect on flotation performance of thionocarbamates as selective collectors for copper sulfide minerals. The order of electron-donating ability is O -isobutyl- N -ethyl-thionocarbamate (IBETC) >  O -isobutyl- N -allyl-thionocarbamate (IBALTC) ≫  O -isobutyl- N -acetyl-thionocarbamate (IBACTC) >  O -isobutyl- N -ethoxycarbonyl-thionocarbamate (IBECTC), and the order of feedback-electron-accepting ability is IBACTC ≈ IBECTC ≫ IBALTC > IBETC. This implies that IBECTC or IBACTC can react with copper atoms having (t 2g ) 6 (e g ) 3 Cu(II) or t 6 e 4 Cu(I) configuration on the surfaces of copper sulfide minerals through normal covalent bond and back donation covalent bond, but the interaction of IBECTC or IBACTC with iron atoms having (t 2g ) 6 (e g ) 0 Fe(II) or (t 2g а ) 3 (e g а ) 2 Fe(III) configuration on the surface of iron sulfide minerals is very weak. IBECTC or IBACTC have excellent performance in these agents as flotation collectors with improved collecting power for copper sulfide minerals and selectivity against iron sulfide minerals. The theoretically obtained results are consistent with the experimental data reported in the literature.
Effects of the mineral phase and valence of vanadium on vanadium extraction from stone coal
The influence of roasting on the leaching rate and valence of vanadium was evaluated during vanadium extraction from stone coal. Vanadium in stone coal is hard to be leached and the leaching rate is less than 10% when the raw ore is leached by 4 mol/L H2SO4 at 90°C for 2 h. After the sample is roasted at 900°C for 2 h, the leaching rate of vanadium reaches the maximum, and more than 70% of vanadium can be leached. The crystal of vanadium-bearing mica minerals decomposes and the content of V(V) increases with the rise of roasting temperature from 600 to 900°C, therefore the leaching rate of vanadium increases significantly with the decomposition of the mica minerals. Some new phases, anorthite for example, form when the roasting temperature reaches 1000°C. A part of vanadium may be enwrapped in the sintered materials and newly formed phases, which may impede the oxidation of low valent vanadium and make the leaching rate of vanadium drop dramatically. The leaching rate of vanadium is not only determined by the valence state of vanadium but also controlled by the decomposition of vanadium-bearing minerals and the existence state of vanadium to a large extent.