Study On The Existing State And Process Mineralogy Of Gold And Tungsten In Xiangxi Gold Deposit

ABSTRACT:The Xiangxi gold deposit is famous for its rich resources of tungsten and antimony consisting of two ore blocks, i.e., Woxi and Yuershan. Through field investigation, polarized light microscopy, X-ray diffraction, X-ray fluorescence spectrum and scanning electron microscopy, this thesis studies the existing state and the process minerlogy of gold in the ores with the results as follows.(1) The properties of the ores both in Woxi and Yuershan are similar. They are both siliceous ores with grade of Au (7.39-10.33g/t), Sb (0.86-4.13%), WO3(0.64-1.95%), SiO2(70.84-80.82%), Al2O3(4.26-6.1%), FeO (2.26-3.15%) and CaO (0.48-1.53%).(2) The ore mineralogy is similar both in Woxi and Yuershan ore blocks, both consisting of pyrite, stibnite, siderite and scheelite, with minor sphalerite, arsenopyrite, wolframite, ilmenite and rutile. But the content of arsenopyrite in Yuershan is higher than that in Woxi.(3) The gold occurs mainly as very fine grains (2-125μ m, average14μ m), filling micro fissures in pyrite, quartz, stibnite, siderite, arsenopyrite and sphalerite. The proportions of gold associated with pyrite, quartz and stibnite are respectively48.41%,39.77%and6.82%More than98%of gold in Woxi is of high purity, mainly as native gold with minor aurostibite.(4) The gold distribution in Yuershan ore block is different from that in Woxi. The former occurs as microinclusions or dispersed gold in sulfides (50.80%) and matrixes (24.11%), with low percent of liberated gold (25.09%); the latter contains high percent of liberated gold (60.35%) and relatively low percent of inclusion gold in sulfides (32.65%).(5) The tailings in Woxi contain up to0.87Au g/t. The proportion of liberation Au is47.62%and inclusion Au in sulfides is20.95%, leading to the optimal ratio of Au at68.57%fr cyanide leaching and recycling sulfides. Gold mainly occurs as fine liberation grains in sulfur concentrate enriched from the tailings with an average grain size of17μ m.(6) The dominant tungsten-bearing mineral of the ores is scheelite (about72-74%) in Woxi and Yuershan ore blocks, with minor wolframite (about24-26%). Scheelite and wolframite occur in cataclastic agglomerate associated with quartz and stibnite with the percents of grain size above200mesh being respectively93.55%and87.74%. The grade of WO3of the tailings is0.012%, composed of scheelite (57.14%) and wolframite (41.67%).Thus the recovery of tungsten from the primary ores is mainly from scheelite, but for the tailings, both scheelite and wolframite must be considered.