A Study On New Leaching Process Of Galena Or Jamesonite Concentrate

The status quo and the trends of technical development of lead and jamesonite concentrate smelting is presented in the paper. Fe2(SiF6)3- H2SiF6-H20 system is a kind of new lixiviant which is applied to the leaching of galena concentrate or jamesonite concentrate. The study on the process of lead leaching of galena concentrate is advanced in our country, and the study on new hydrometallurgical process of lead and antimony extraction of jamesonite with a ferric fluosilicate solution is more advanced and important, which has not been reported. Theory study first gives chemical theory knowledge of fluosilicate acid and its salts aqueous solution. Nature and composition and equilibra in the H2SiF6 aqueous solution, and chemical reactions probably with ores in the leaching in the fluosilicate acid medium, such factors as temperature, concentration and so on affecting on stability of and vapor over H2SIF6 aqueous solution are discussed. Then the thermodynamics of the leaching of galena and antimonite concentration with the ferric fluosilicate solution is investigated. In the lixiviant, SiF62 in the forms of oxidation property is stable, and moreover, ferric and flousilicate complexes exist in the solution, which have some effect on the potential of ferric ion. Certain acidity is needed to be held out in the antimonite concentrate leaching. There is possibility that lead elemental becomes PbSO4 and consequently remains in the residues, thereby limiting the fractional Pb extraction in the leaching ofjamesonite concentrate. The study on new process of galena leaching is emphasized, and the experimental results show that the process of lead leaching galena concentrate is possible, and fractional Pb extraction is 96 percent. Surfacechemical reaction mechanism is responsible fOr the overall leaching rate,and temperature have significant effect on the dissolution of the galenaconcentrates. The optimized leaching conditions of galena concentratesare as follows: @temperature ranges 50 to 65C, @H,SiF, concentrationin the lixiviant is l5--50 g/L, @Fe'+ is 35--50 g/L, @leaching fOr 4--6 h with -250 mesh, and prolonged with larger particle size. @pulpdensity is 30ho70 g/L. A proposed process for galena leaching is alsogiven. The lead sulfide concentrate is first leached with a ferricfluosilicate solution. The leach slurry is then washed and filtrated. Theresidue containing elemental sulfur and precious metals is sent for furthertreatment, while the fluosilicate leach solution containing dissolved leadcould be purified by adding lead powder to cement copper, bismuth, andantimony from the leach solution. The purified leach solution is sent to anelectrolytic cell with a porous diaPhragm for lead electrowinning. Thelead ion is reduced to lead metal on the cathode, while the ferrous in theleach solution is oxidized on the anode to regenerate the ferric fluosilicatesolution that is recycled for further treatment of the galena concentrate.On the other hand, the study on new leaching process ofjamesoniteconcentrates has been investigated. Fractional Pb extraction is 78 percent,and antimony is 94 per cent. The leaching control mechanism is discussed,and internal diffusion through solid production possibIy plays importantrole in the overall leaching rate. The optimized leaching conditions ofjamesonite concentrates are as followst Otemperature: 50--65 C, @H,SiF,f 25-- 130 g/L, @Fe'+f 35--50 g/L, @leaching for l2 h with -300mesh, and prolonged with larger particle size. @pulp densityt 45--70g/L. The princip1ed flow sheet of the process for jamesonite leaching issimilar to that of the galena leaching process but a difference is that metalreduced on the cathode is the lead and antimony aIloy. Some sc...