The Synthesis Of Xanthate Orgnic Depressant And Its Depressing Mechanisms In Zinc-iron Sulfide Minerals

The contents of studies in this paper include following five aspects:the crystal structure and surface property of marmatite,arsenopyrite andpyrrhotite, the design and synthesization of the xanthogenate organicdepressants, the depressing capability of the synthesized organicdepressants on zinc-iron sulphids minerals and effect on electrochemicalflotation of these minerals, the depressing mechanism of the organicdepressants based on zeta potential,Infrared spectrum and ultravioletspectrophotometer tests, the structure-activity relationship of the organicdepressants in the light of the flotation reagents characteristic indexnumber i and hydrophilic lipophilic balance (HLB).1. X-radial diffract datas of three minerals show that X-radialdiffract datas of the samples are as same as standard diffract datas ofJCPDS of Marmatite-Cubic, Arsenopyrite-Triclinic and Pyrrhotite-Trigonal. It is affirmed that marmatite (Guangxi province Dachang ) isof Marmatite-Cubic, arsenopyrite (Hunan province Yaoguangxian) is ofArsenopyrite-Triclinic, Pyrrhotite(Guangxi province Dachang)is ofPyrrhotite-Trigonal. Marmatite, arsenopyrite and pyrrhotite is floatableusing collector butyl xanthate, butyl amine aerofloat, anddiethyldithiocarbamate. Marmatite has good floatability from pH2 topH12 after it is activated by Cu²⁺ions, besides arsenopyrite and pyrrhotitecan also be activated.2. Seven polyhydroxy xanthogenate organic depressant compoundsare synthesized according to molecular design theory of organicdepressant, namely sodium 2-hydroxyethyl carbonyl dithiocarbonate,sodium 2,3-dihydroxypropyl dithiocarbonate, sodium 2, 3, 4, 5,6-quinthydroxyhexyl carbonyl dithiocarbonic, sodium acetate carbonyldithiocarbonate,sodium propionate carbonyl dithiocarbonate, 1-sodiumformate-2-hydroxy carbonyl dithiocarbonate, 1-sodium formate-1-sodium acetate carbonyl dithiocarbonat. Reaction products and theirpurity are ascertained through infrared spectral analysis and chemicalelement analysis.Floatation test shows that polyhydroxy xanthogenate has despression effect on zinc iron sulphid minerals, the order of despression capacity isarsenopyrite＞pyrrhotite＞marmatite. In the presence of Cu²⁺ions,polyhydroxy xanthogenate has weak despression effect on marmatite,nevertheless, it has stronger despression effect on pyrrhotite andarsenopyrite. Marmatite,arsenopyrite and pyrrhotite can be separatedthrough flotation in the range of pH over than 6.Flotation separation of three artificial mixed minerals aboutzinc-arsenic,zinc-sulfur and zinc-arsenic-sulfur separation can be cometrue when 1-sodium formate-1-sodium acetate carbonyl dithiocarbonicacid sodium is used as depressant. This shows that synthesizedxanthogen orgnic depressant is in favorable possession of applicationforeground and investigation value on flotation separation of zinc ironsulphid ores.3. The flotation behaviors of marmatite, arsenopyrite and pyrrhotiteare related to the pulp potential with the butyl-xanthogenate as collector.The potential area that the minerals can be floated is bigger in the low pHthan in the high pH. When the xanthogenate-group depressant is used,marmatite has a wide floated Eh area while the arsenopyrite andpyrrhotite only have a narrow floated Eh area in the low pH, so themarmatite can be separated from the arsenopyrite and pyrrhotite in thelow pH by potential control. But three of them can't almost be floated inthe high pH and they can't be separated.4. The order about the adsorption of the xanthogenate-groupdepressant on the surfaces of sulfides is arsenopyrite＞pyrrhotite＞marmatite corresponding to the depression intensity of the depressant onmineral. The adsorption density of the xanthogenate-group depressantincreases with the pH and arrives the biggest level when the pH≥6.0.The adsorption of on the surface of arsenopyrite and pyrrhotite is morethan on the surface of marmatite.The depression of the organic depressants are also indicated by thechange of the zeta-potential of the minerals which are interacted with thefloat reagents. The change of the zeta-potential is more by themulti-carboxylic xanthogenate than by the multi-hydroxy xanthogenate.With the increase of the concentration of the organic depressant, the zeta-potential of the minerals decreases continually and arrives ainvariable level when the reagents are used with a larger quantity. Thezeta-potential of the arsenopyrite is the lowest, the pyrrhotite takes thesecond place, and the one of marmatite is on the top, this result indicatesthat the order of adsorption intensity of the depressant is arsenopyrite＞pyrrhotite＞marmatite. Because the anion organic depressant can beintensive adsorption on the negative surfaces of the minerals, theinteraction between the reagents can be probably a kind of chemicaladsorption.The infrared spectra of the interaction between the xanthogenate-group depressant and the zinc iron sulphid minerals show that these twokinds of depressants are chemically interacted with the minerals. TheCu²⁺ on the surface of the marmatite reacted with the butyl xanthate andmakes Cu(BX)₂ in the presence of Cu²⁺, butyl xanthate andxanthogenate-group depressant, so the xanthogenate-group depressantloses the depression to the marmatite while still keeps the gooddepression to the arsenopyrite and the pyrrhotite.5. The more the hydrophilic group in the organic compounds, thestronger the depression to the minerals. Polyhydroxy xanthogenateorganic depressant(GX) has the order of hydrophilic groupGX3＞GX2＞GX1,So that the depression capability is GX3＞GX2＞GX1,Similarly, for the polycarboxyl xanthogenate organic depressant, thenumber of hydrophilic-COOH and hence the depression capability isTX4＞TX3＞TX2＞TX1.The depression capability of the xanthogenate organic depressantincreases with the characteristic index i and the value of hydrophiliclipophilic balance (HLB), the bigger the index and the HLB value, thestronger the hydrophilic performance, and the more the depressioncapability. Their order is also GX3＞GX2＞GX1 to the polyhydroxyxanthogenate organic depressant and TX4＞TX3＞TX2＞TX1 to thepolycarboxyl xanthogenate organic depressant.