Effect of Sodium Sulfite on Floatability of Chalcopyrite and Molybdenite

Abstract

Sodium hydrogen sulfide (NaHS) is commonly used as a copper depressant in the selective flotation of copper and molybdenum ores. However, the process is facing health and safety issues because NaHS readily yields toxic hydrogen sulfide gas (H 2 S) under acidic conditions. In this study, Na 2 SO 3 was proposed as an alternative copper depressant. The effect of Na 2 SO 3 on the surface wettability and floatability of chalcopyrite and molybdenite-typical copper and molybdenum minerals, respectively-was intensively studied using contact angle measurements and flotation tests. Contact angle readings show that the chalcopyrite surface became hydrophilic after the Na 2 SO 3 treatment. Meanwhile, the molybdenite surface was relatively more hydrophobic compared with that of chalcopyrite after the treatment. Flotation tests using pure minerals of chalcopyrite and molybdenite demonstrate that the floatability of chalcopyrite decreased with increasing concentration of Na 2 SO 3. On the other hand, the floatability of molybdenite gradually increased under similar conditions, suggesting that Na 2 SO 3 might have the potential to be used for selective flotation of chalcopyrite and molybdenite. A possible mechanism is proposed in this study to explain the phenomenon using X-ray photoelectron spectroscopy analysis.

On the use of Na₂SO₃ as a pyrite depressant in saline systems and the presence of kaolinite

“…The effects of Na2SO3 in the chalcopyrite without the presence of a collector showed maximum recoveries of 20%. This effect is attributed to the interaction of Na2SO3 in active iron sites and its reducing effect, as suggested by Miki et al (2018) in their study of chalcopyrite and molybdenite minerals. The chalcopyrite, in the presence of the depressant shown in Fig.…”

“…An increase in the dose of Na2SO3 affected the recovery of the chalcopyrite in the presence of the minimum and maximum values of IPETC. The above was explained by Miki et al (2018), who determined that increasing the dose of Na2SO3 reduces the hydrophobicity of pure chalcopyrite. At its midpoint, further recovery can be achieved.…”

“…Among them, sodium sulfite (Na2SO3) has been investigated as a pyrite depressant in copper sulfides (Molaei et al, 2018), enargite (Haga et al, 2012), copper depressant in minerals associated with molybdenite (Miki et al, 2018), and arsenopyrite from gold ores (Kydros K. , Angelidis T., 1993). However, these studies used fresh water for their evaluation.…”

An Alternative Depressant of Chalcopyrite in Cu–Mo Differential Flotation and Its Interaction Mechanism

“…The mineral suspension was prepared by adding 25 g of mineral powder to 100 mL of solution while using a stirrer to agitate. The pH of the mineral suspension was first adjusted to the desired value (2,4,6,8,10,12) with concentrated NaOH or H 2 SO 4 stock solution. The prepared CMC solution was added to the desired concentration while conditioned for 5 min.…”

“…As molybdenite is inherently more floatable than chalcopyrite [6], chalcopyrite is inhibited by a depressant that selectively hinders the collector adsorption to chalcopyrite or increases the hydrophilicity of chalcopyrite during the separation. The most routinely used chalcopyrite depressants are inorganic reagents such as sodium sulfide [7][8][9][10], sodium thioglycolate [11,12] and sodium cyanide [13]. These reagents are extremely toxic and applied in high amounts, which are harmful to both humans and the environment.…”