Research Of Crystal Chemistry On Flotation Of Several Sulfate Minerals

Celestite(SrSO4), barite(BaSO4) and gypsum(CaSO4·2H2O) are three kind of important sulfate minerals, which are also important salt minerals used widely in architecture, chemical industry and medical fields. Barite is a main raw material for extracting barium salt. Celestite is the main source of strontium carbonate, which is often used for producing kinescope panel glasses of TV sets and permanent-magnet materials. Gypsum is a kind of more important nonmetal material, used widely in the field of industry, agriculture and medicine.The flotation of Celestite, barite and gypsum is a significant topic of theory and practice. The three sulfate minerals usually accompany with these salt minerals, having ions with equal activities or similar properties on the surface, which makes the flotation separation difficult. At present, the research on the flotation of the three sulfate minerals mainly laid special emphasis on studying flotation separation between the three sulfate minerals and other salt minerals including calcite, apatite, and fluorite and so on.The floatability of minerals is closed related with their crystal chemistry characteristics. The crystal chemistry characteristics includes chemical composition, chemical bonds, crystal structure and the relation among them, which decide the surface properties of minerals after dissociating in the solution, and then influence the floatability. Consequently, this paper carried out the crystal chemical research on the flotation of the three sulfate minerals.This paper started from the crystal structure, and carried out the systematic study through vast scale flotation experiments on the floatability of the three sulfate minerals without activator and depressant in anion, cation and chelating collectors flotation system, and influence of polyvalent metal cation, inorganic anion modifiers, organic high molecular depressants and organic chelating agents on floatability of them. At the same time, the studies on crystal structures of three typical sulfate minerals with the aid of theory of crystal chemistry, theory of solution chemistry of flotation and modern advanced surface test technique (X-ray photoelectron spectrometric,ζ-potential measure) were carried out for research of crystal chemistry on three sulfate minerals in this paper, and computer simulation calculation was also attempted to carry out for verifying the results of flotation.The research shows that the floatability sequence of three sulfate minerals is barite>celestite>gypsum in the collector systems of sodium oleate and salicylhydroxamic acid; in lauryl amine system is:gypsum>celestite>barite. XPS and infrared spectrum analysis are used to find that it is chemical reaction between sodium oleate and three minerals, physical adsorption on the surface of minerals for lauryl amine, and it is chelating reaction between salicylhydroxamic acid and three minerals possibly.Theoretical calculation on chemical bonds in crystal structures of three minerals is carried out, finding that the bond length, bond energy, coulomb force, percentage and polarity of ionic bond and bonding strength determine the breaking level of Mn+—O2- when minerals dissociate in flotation system, and the breaking level of Mn+—O2- in crystal structures of three sulfate minerals is closed related with floatability. As to celestite and barite, The Ba-O, Sr-O bonds break largely and much Sr2+,Ba2+ exposing on the surfaces, which can generate chemical reaction with sodium oleate, and chelating reaction with salicylhydroxamic acid, so celestite and barite have good floatability in the systems of sodium oleate and salicylhydroxamic acid.The bond Ca-O in gypsum structure is more difficult to break, and Ca2+ exposes very little, so the electronegativity on the surface of gypsum is higher, which leads to a good floatability in the flotation system of lauryl amine, better than in the sodium oleate and salicylhydroxamic acid flotation systems. The results of computer aided calculation are accordant with the flotation experiments results, showing that the reaction energy of mineral and reagent changes more, the floatability is better.