The entrainment of Mg-containing chlorite usually occurs during marmatite flotation, which further deteriorates the smelting of zinc concentrate. In this study, the flotation behavior of marmatite and chlorite were investigated, which disclosed that fine-grained chlorite was more floatable and easily entered into zinc concentrate than coarse-grained chlorite. The combined water glass (AWG) and sodium citrate (SC) has been confirmed excellent chlorite depressant, which could decrease the grade of MgO from 3.45 % to 0.31 % in zinc concentrate. XPS and reagent adsorption analysis uncovered that Cu 2+ would not adhere and induce collector ML-8 attach to chlorite surface, meaning the entrainment of chlorite was not caused by activation flotation. The moisture of foam for fine-grained chlorite flotation is much higher than of marmatite, confirming that foam for chlorite flotation is not mineralized, and the collection of chlorites was caused by foam entrainment. Moreover, AWG and SC could selectively adsorb on the chlorite surface and reduce its contact angle to 16.85°. Eventually, SEM-EDS detection further revealed that the entrainment of fine-grained chlorite in zinc concentrate was almost disappeared after using the combined AWG and SC to increase the surface wettability of chlorite. The actual ore flotation further confirmed its excellent inhibitory effect on selectivity.
Yun Li,Zelong Huang,Liyuan Chai,Yunyan Wang,Xin Wang,Yong Ke,Cong Peng,Xiaobo Min
High-silica-calcium oxygen-sulfur mixed lead-zinc (HSC-PbZnOS) ore is a complex and refractory resource. This study proposed a novel and cleaner process to extract zinc and conserve sulfur and calcium in CaS form from HSC-PbZnOS concentrate. After mineral composition characterization of HSC-PbZnOS concentrate, thermodynamic and experimental investigations reveal that zinc oxides can be directly reduced by carbon, ZnS first reacted with CaO above 770 ℃ to form a stable intermediate CaZnSO (CaO + ZnS → CaZnSO), which is subsequently reduced above 1126 ℃ to Zn(g) and CaS (CaZnSO + C → Zn(g) + CO + CaS). Thus sulfur was fixed as CaS and SO₂ emission was avoided. SiO₂ tended to react with CaO to form silicates, partially inhibiting sulfur-fixation. However, under reducing conditions around 1300 ℃, silicate decomposed to release CaO, allowing it to regain reactivity with ZnS. In addition, pilot tests show that adding 10 wt% limestone increased the Zn reduction rate to 98.9% and the sulfur fixation rate to 98.1%. The gaseous product was ZnO, and the residue mainly consisted of individual SiO₂ and CaS. This work provides a clean, short-process route for efficient utilization of complex HSC-PbZnOS resources with industrial potential.
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