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2 Physicochemical Problems of Mineral Processing

2 2019

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Function and mechanism of sodium silicate in the cleaning process of ilmenite rough concentrate

100%

Xiong K. , Wen S. , Deng J. , Cai J. , Lv M.

2019

tom Vol. 55, iss. 5

1099--1107

The grade of titanium dioxide (TiO2) from Panzhihua titanium concentrate (defined as the ilmenite rough concentrate in this paper) is generally around 47%. The high impurity content in the titanium concentrate causes difficulties for its successive use in the production of titania pigment. Further purification of the ilmenite concentrate will make it more useful for industrial use. In this study, a further cleaning process of the ilmenite rough concentrate is conducted using sodium silicate as the depressant, and the function of sodium silicate is determined by flotation, absorption measurements, Zeta potential measurements, and infrared spectral analysis. The results indicate that an ilmenite concentrate with a TiO2 grade of 50.37% can be achieved from 46.78% according to the stages on the flowsheet-one roughing, three cleaning and one scavenging-under the optimal conditions, and can also reflect the advantages of the excellent selectivity of sodium silicate. Sodium silicate can hinder the adsorption of salicylhydroxamic acid (SHA) on the titanaugite surface but has almost no effect on ilmenite. Multiple methods comprehensively confirm that sodium silicate provides a good selective depression effect for the further purification of the ilmenite rough concentrate.

Gold recovery from refractory gold concentrates by pressure oxidation pre-treatment and thiosulfate leaching

72%

Yu L. , Li S. , Liu Q. , Deng J. , Luo B. , Liang Y. , Zhao L. , Lai H.

2019

tom Vol. 55, iss. 2

537--551

Naturally, refractory gold is enclosed by sulfide minerals such as pyrite and arsenopyrite and a higher content of organic carbon, which results in difficulty in the recovery of gold. In this study, the flotation gold concentrate before and after pressure oxidation (POX) was analyzed. The analysis of the Eh-pH diagram revealed that pyrite/arsenopyrite would be dissolved in higher oxidation potential. Results of SEM-EDS showed that the surface of minerals became very rough and structure of some particles was destroyed after POX. The XRD measurement showed that pyrite was oxidized to jarosite, and gangue minerals such as quartz and organic carbon were hardly changed. The process of thiosulfate leaching of gold was designed and optimized according to Miscellaneous implemented by Response Surface Methodology (RSM). Based on the results of ANOVA, leaching model was significant. In leaching, [S2O32-] played an important role and the interactions between [S2O32-] and [Cu2+] were significant. The effect of [HA] was relatively weak. Optimum process parameters of the initial reagent concentration were 505.00 mM for [S2O32-], 34.77 mM for [Cu2+], and 0.50 mM for [HA]. Under these conditions, the Au extraction value was about 86.21%, which was significantly higher than that obtained with leaching directly.