Study On Processing Mineralogy And The Utilization Of The Nepheline Ore In Nanjiang Sichuan

Nepheline is a kind of alkaline aluminosilicate mineral resource from whichaluminium, silicon, sodium and potassium can be recycled and utilized. At present,this kind of mineral resource is mainly applied in glass and ceramic industry in the US,Canada, Norway, etc. While it is mostly used for alumina preparation in Russia, andthe byproducts such as soda, potash, cement can be obtained at the same time. Thenepheline resources are abundant and widely distributed in China, which are mostlyused as raw materials in glass and ceramic.There is only one rock type, urtite, among the nepheline ores in NanjiangSichuan. The nepheline content is always2-3times as the other types of nephline,which is the most remarkable unique nature leads to the great value of utilization forits high content of nepheline. Additionally, the promising reserves are estimated asmuch as21million tons[1]which can guarantee a long term exploitation andapplication. As a result of lower level of research and utilization compared with theUS, Canada, Norway and Russia, most of the nepheline ores in China are used asprimary raw materials of producing glasses and ceramics. And the condition ofutilization of this mineral resource is unsatisfied. Most studies about the Nanjiangnepheline are in the categories of geological formation and beneficiation processing,and the reports of utilization of this ore has never been seen. Therefore, studies on theprocessing mineralogical characteristics and beneficiation technologies of theNanjiang nepheline ore, and experiments on the preparation of alumina from the orecan be conducive to the utilization of this mineral resource.In the study of processing mineralogy, various analyzing and characterizationmethods were employed to investigate the compositional, textural features, etc. Thechemical composition of the ore was investigated by XRF, beyond that the Fe2+andFe3+were detected by volumetric method and atomic absorption method respectively.The mineral constitution of the ore was analyzed by XRD. The morphology of eachmineral in the ore was observed by optical microscope, and the mineral particledistribution was counted under the microscope and concluded with mathematic method. The chemical composition in mono-mineral and the elements distributionwere investigated by SEM-EDS technology.In the beneficiation studies, the nepheline ores were subjected to gravityseparation, wet magnetic separation, dry magnetic separation and reverse flotation.The grinding fineness and pulp concentration were taken into consideration in thebeneficiation process as influence factors. The optimal technological parameters weredetermined in both magnetic separation and flotation. Finally, the combined schemeof beneficiation, wet magnetic separation-dry magnetic separation, was believed asthe most efficient optimal beneficiation technology. With the combined beneficiationtechnology, the nepheline concentrates with0.12%Fe2O3content which can be usedas raw materials of optical glass were obtained.In the experiments of preparation of alumina, the nepheline concentrates wereselected as raw materials to be calcinated at1200℃for2hours mixed with CaCO3.Then, the resultant of calcination were dissolved in alkali liquor with pH=11at80℃for50minutes. The precursor Al(OH)3was obtained with introducing excessive CO2into the dissolved filtrate prior to obtaining Al2O3(95wt.%) via making the precursorannealed at a certain temperature. The product Al2O3mainly comprised-Al2O3,besides θ-Al2O3and κ-Al2O3were also existed in the final powder.