Influence Of Physicochemical Factors In Grinding Process On The Floatability Of Several Carbonate Minerals

Carbonate minerals are very important nonmetal mineral materials, an important mineral source of extracting metal, such as Fe、Mg、Mn、Pb、Zn、Cu and radioactive element and rare earth elements. It is of great economic significance to the world. With sulphide ore and rich ore resources exhausted day by day, the development and utilization of Carbonate minerals draw more and more attention. Calcite and dolomite coexists valuable minerals as gangue minerals usually. Many flotation processes involve the separate of valuable minerals with carbonate minerals. So it is of great significance to the flotation theory and industrial practice of salt minerals to research on the flotation behaviors of carbonate minerals.The research of carbonate flotation is mainly focus on the develop of flotation reagents, flotation mechanism research and flotation process improvement. But the relationship between grinding and flotation of carbonate minerals is paid little attention by the mineral processing researchers. Grinding is not only substantial to decrease the size and consequently to liberate the valuable minerals from its gangue to allow for their selective recovery during mineral processing processes such as flotation but also to influence the flotation behavior significantly. Many researches and industrial practices showed that the interactions between the ore and the grinding environment affect sulphide both in recovery and selectivity. It has an important theory and practice significance to study the affect of grinding on the flotation behavior of carbonate minerals and to search for the relationship and regularity between physicochemical factors of grinding process and flotation behavior of carbonate minerals.The study was undertaken using four carbonate minerals, including calcite, malachite, calamine and magnesite and a common gangue mineral, quartz. The influence of different grinding media, different grinding mode and the flotation reagents addition site on the flotation of five minerals using sodium oleate and lauryl amine as collector respectively was investigated using advanced surface and solution test technology such as X-ray photoelectron spectrometric (XPS), atomic absorption spectrometry (AAS) analysis andζpotential measure. And the effecting mechanism of grinding environment on floatability of five minerals was discussed.It is showed that grinding with zirconia media is beneficial to the flotation of carbonate minerals using sodium oleate as collector than grinding with steel media, but grinding with steel media can activate the flotation of quartz obviously. And grinding with steel media depresses the flotation of all five minerals when using lauryl amine as collector. It may be attributed to the electrochemical corrosion of steel media in grinding. The iron will be oxidized and oxygen in the solution be reduced subjected to the abrasion diversity corrosion and galvanic corrosion. It is showed that the species in slurry after grinding with steel ball are mainly Fe(OH)3 based on the (Eh, pH) value of slurry and the Eh-pH phase digram of Fe-H2O system. And the solution test shows that there is soluble Fe phase in slurry solution, which may be Fe2+ and its hydroxy complexes. The adsorption of Fe(OH)3, Fe2+ and its hydroxy complexes in the minerals surface may change the surface electricity and surface properties, then effect the minerals floatability.The influence law of wet and dry grinding on the flotation of four carbonate minerals is different. The floatability of malachite using sodium oleate as collector after wet grinding with zirconia media is better than dry grinding, but the floatability of malachite after dry grinding with steel media is better than wet grinding. The floatability of calcite after dry grinding is better than wet grinding, while the floatability of calamine and magnesite after dry grinding is worse than wet grinidng with both kind of grinding media. When using lauryl amine as collector, the floatability of calcite after wet grinding is better than dry grinding, while the floatability of calamine and magnesite after dry grinding is better than wet grinidng with both kind of grinding media.The XPS surface elements test shows that, wet and dry grinding process makes the distribution difference of surface anion and metal cation, then influence the floatability of carbonate minerals using sodium oleate and lauryl amine as collector. An assumption of "the flotation difference of carbonate after wet and dry grinding is the flotation difference between initial state and equilibrium state of carbonate dissolution" was made out according to the analysis of the carbonate crystal structure and solubility properties. And the "Stirring time" test andζpotential measurement were carried out to verify the validity of the assumption. The floatability of calamine and magnesite has good correlation with the assumption but the floatability of malachite and calcite shows a poor correlation.Flotation separation experiment of four groups of mixed mineral was carried out using sodium oleate as collector. The separation effect of malachite-quartz system wet grinding with zirconia is relatively superior. The selectivity index of grinding with zirconia media is higher than grinding with steel media under the same condition.