Research On The Theory And Technology Of Cervantite Sulphidizing Flotation

The flotation separation of antimony oxides from gangue minerals is a hard problem in the field of minerals processing in the world, particularly in terms of the complicated composition and poor flotability of antimony oxides, as well as the similar surface physicochemical properties of antimony oxides to that of the gangue minerals, which results in serious interference with each other during the flotation process. Hence the antimony oxides shall be preprocessed to a certain extent so as to improve their flotability and achieve the separation of antimony oxides from gangue minerals.Taking the cervantite from the northern concentrator of Hunan Tin Mine as the samples, and using the technical ideas of sulphidizing flotation, the researches in this paper are conducted including the sulphidizing flotation at normal temperature and roasting sulphidization-flotation. The sulphidizing efficiency of cervantite and the sulphidizing mechanism are systematically studied in this paper by using the flotation experiments, x-ray photoelectron spectroscopy (XPS), x-ray diffraction spectrometry (XRD), polarizing microscope and scanning electron microscopy (SEM), as well as the calculation of flotation solution chemistry and reaction chermodynamics, Main contents and results are as follows:Based on the results of sulphidizating flotation at normal temperature for pure minerals, it can be found that there is a significant synergistic effect between the lead ion and sodium sulfide on the sulphidizing of cervantite. When the suitable ratio and dosage of lead ion and sodium sulfide were used in a suitable pulp, cervantite performs out a good flotability, but quartz and calcite perform poor flotabilities under the same conditions, and it may contribute to effective separation of the cervantite from quartz and calcite. Meanwhile, dithiophosphate BA shows a good selective collectivity to the sulphidized cervantite, and butyl polyglycols shows the selective strengthening of the cervantite flotation froth.The mechanisms of the sulphidizing flotation at normal temperature on cervantite are shown as:lead ions, absorbed on cervantite surface by electrostatic or chemical interaction, react with sodium sulfide and form a certain thickness of PbS on cervantite, then it improve the cervantite’s flotability.Based on the experiments of roasting sulphidization-flotation of cervantite, it can be found that the best flotability of cervantite can be got from roasting products under the condition of a natural pH, the sulfur-antimony molar ratio of0.9, roasting temperature of450℃and the roasting time of30minutes. The best flotation reagent conditions are the lead ion of5×10-4mol/L, isoamyl xanthate of60mg/L and pine camphor oil of40mg/L. The flotability of gangue minerals are extremely poor under the same conditions, and it makes the flotation separation of cervantite from gangues possible.The mechanisms of the roasting sulphidization flotation on cervantite are shown as:there is a high-temperature reaction between the cervantite and the liquid elemental sulfur, which may experience the change process from Sb2O4, Sb2O3(c/Sb2O3(O) to Sb2S3. When the content of sulfur is insufficient, there will be a thin layer of antimony sulfides formed on cervantite surface, and the sulphidizating will gradually get inside of cervantite particles with the increase of sulfur content, and the whole cervantite particle will be sulphidized finally. Gangue minerals, such as quartz and calcite, do not react with elemental sulfur under the same conditions.The results of roasting sulphidization flotation on a stibnite flotation tailings contains cervantite shown that a rougher concentrate with the grade of6.47%Sb and the recovery of73.49%Sb has been produced from the feed with the grade of1.03%Sb.