Search

This study describes the first, use of eco-friendly welan gum as a new depressant in galena-pyrite flotation separation. The depression mechanism were examined using micro-flotation and various characterization techniques. The selective depression performance of welan gum on pyrite was found to effectively enhance the galena/pyrite flotation separation index. Compared with the addition of NaBX alone, the grade of Pb in the produced concentrate increased by more than 28% (from 40.86% to 70.02%). And it was possible to recover 87.79% of galena and only 15.98% of pyrite. There was an accentuated increase in the electronegativity of the pyrite surface by more than ~ 8 mV after treatment with welan gum alone compared to an increase of ~ 1 mV for galena, which can be explained by the fact that welan gum selectively adsorbed on the pyrite surface in significant amounts. As a result, the subsequent adsorption of xanthate is prevented. This finding has been further proven by adsorption measurement results. The X-ray photoelectron spectroscopy and Time-of-Flight secondary ion mass spectrometry results indicated that the hydroxyl groups in welan gum showed acid – base interactions with the metal hydroxylated species anchored on the mineral surfaces, which may be the main driving force in the adsorption process. Differences in the amount of metal hydroxide on the mineral surface, as well as the electrical affinity of metal ions in metal hydroxide, contributed to the selective adsorption of welan gum. Therefore, welan gum can be regarded as a potential pyrite-depressant. [ABSTRACT FROM AUTHOR]

• A high solution pH is favorable for pyrite and arsenopyrite oxidation. • Arsenopyrite has a higher Fermi level and lower open circuit potential than pyrite. • Arsenopyrite oxidation is thermodynamically preferred over pyrite. • Arsenopyrite oxidation has a faster rate compared to pyrite. This study systematically investigated the surface oxidation behavior differences between pyrite and arsenopyrite under neutral and alkaline pH conditions using various electrochemical measurements. These measurements include open circuit potential (OCP), cyclic voltammetry (CV), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analyses. Key electrochemical parameters have been obtained. The OCP, oxidation potential (E ox), and charge transfer resistance (R ct) of arsenopyrite and pyrite declined as the solution pH increased, but oxidation current density (j ox) and carrier concentration (N D) increased, suggesting that a high solution pH is thermodynamically and dynamically favorable for the oxidation of both pyrite and arsenopyrite. Compared to pyrite, arsenopyrite has a higher Fermi level, lower OCP and E ox , a larger j ox , and a smaller R ct at the same pH conditions, suggesting that arsenopyrite oxidation has a higher thermodynamic preference and occurs at a faster rate than pyrite oxidation under neutral and alkaline pH conditions. This comprehensive study enhances our understanding of the oxidation difference between pyrite and arsenopyrite and offers important guidance for the pyrite-arsenopyrite flotation separation when using the selective surface oxidation method. [ABSTRACT FROM AUTHOR]

Arsenic is hazardous to the environment, and needs special precautions in smelting operations. The separation of pyrite and arsenopyrite is therefore required; however, the process is difficult. The present work employed the combination of sodium carbonate (Na 2 CO 3) and sodium humate (HA) as arsenopyrite depressants. In this regard, flotation tests, zeta potential measurements, adsorption tests and electrochemical measurements were performed. The microflotation tests showed that regardless of the presence or absence of copper sulfate, the recoveries vs. pH of both minerals were quite similar, thereby showing the difficulty of separation. Using copper sulfate is required in achieving flotation separation under weak alkaline. HA alone could depress the arsenopyrite flotation and show good selectivity towards pyrite. Interestingly, compared to the single depressant of sodium humate, higher pyrite and lower arsenopyrite recoveries were obtained when using the combination. The zeta potential, adsorption capacity and cyclic voltammetry showed that HA could strongly adsorb on arsenopyrite, whilst the adsorption on pyrite is weaker. More importantly, the presence of Na 2 CO 3 enhanced the adsorption of HA on arsenopyrite, but reduces that on pyrite, which is consistent with the flotation results. A satisfactory flotation performance was obtained after a closed-circuit flotation using the combined depressants. This work puts forward an environmentally friendly strategy for the separation of pyrite and arsenopyrite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 2 SO 3 replaces a part of CaO in the galena-pyrite mixed concentrate flotation separation.. • Na 2 SO 3 has a significant depression effect on EX-preadsorbed pyrite. • Na 2 SO 3 can desorbed xanthate species on pyrite surface. Galena, sphalerite, and pyrite are important metallic sulfide minerals and are often associated with one another. In the flotation separation of galena-pyrite mixed concentrate, large amounts of lime (CaO) are used for the depression of pyrite. In this study, the negative effects of lime were reduced by using an efficient depressant Na 2 SO 3 + CaO reagent in the flotation separation of galena from pyrite. Real ore sample flotation separation tests showed that the mixed depressant can efficiently depress pyrite from galena-pyrite mixed concentrate. The obtained galena concentrate had a Pb recovery and grade of 58.36% and 83.45%, respectively. Micro-flotation experiments showed that Na 2 SO 3 depressed the floatability of pyrite more strongly than that of galena. Moreover, the depression mechanism of Na 2 SO 3 was observed through contact angle measurements, ultraviolet–visible spectrophotometry (UV–Vis) analysis, and time of flight secondary ion mass spectrometry (TOF-SIMS). This study provides an important reference for the depression of pyrite from a galena-pyrite mixed concentrate with low lime dosage. [ABSTRACT FROM AUTHOR]