Electrochemical investigation of
mineral electrodes in alkaline solution
D. Erdenechimeg1, B. Maralmaa1, B. Oyun1 , A.V. Kashevskii2
1School
of Engineering and Applied Sciences, National University of Mongolia, St. University, Ulaanbaatar, Mongolia, 976.
2 Faculty of Chemistry, Irkutsk State University, Russia St. Lermontov -126, 644009.
ABSTRACT:
RESULTS AND DISCUSSION
Cyclic voltammetric methods have been applied to study the electrochemical
behavior of the sulfide minerals (chalcopyrite and pyrite) in alkaline solution of
phosphate-buffered and the sodium sulfide. The redox process of electrodes of
sulfide ores was investigated using silicone-impregnated graphite electrode.
The cathodic and anodic reaction products in alkaline solution was determined
within the potential range of -2V to +2V (vs. Ag/AgCl). Due to the oxidative
process, oxidized formation of FeS, FeS2, and FeOOH were observed on the
pyrite electrode in sodium sulfide solution at an approximately potentials such
as -0.5V and +1V. On the other hand, meta-stable formation of CuFe(1-x)S2 and
compounds of Cu2S, CuS and CuO were formed on the surface of chalcopyrite
electrode, respectively.
Fig1. Cyclic voltammograms measured on electrode "Gr"
APB saline in 0.1 M, pH 7.4, ν=50mV/sec three consecutive
cycles.
Fig. 2. Cyclic voltammograms of electrode "Pyr2"
APB in 0.1M, pH 7.4, ν=50 mV/sec three consecutive
cycles in -350 - 1500mV.
Keywords: electrochemical method, chalcopyrite, pyrite, sodium sulfide,
flotation
Preparation of the electrode
MATERIALS AND METHODS:
Fig. 3. Cyclic voltammograms of electrode "Pyr2" APB in
0.1M, pH 7.4, ν=50mV/sec three consecutive cycles in -350 1500 mV, The scale of the axes is changed from Fig.3.
Chalcopyrite
Chalcopyrite electrode
Pyrite
Pyrite electrode
Electrochemical measurement
Fig. 5. Voltammogram of pyrite electrode in alkaline (pH=12)
solution of sodium sulfide at a potential scan rate 50mV/s
→ → 0.3В
→ 2 0.2В
19 → 2 9 15 0.8В
Fig. 4. Voltammogram measured on a graphite
electrode in alkaline (pH = 12) solution of sodium
sulfide at a potential scan rate of 50 mV/sec
Fig. 7. The cyclic voltammogram measured at
chalcopyrite electrode in alkaline solution of sodium
sulphide (pH = 12) (scan rate ~50mV/sec)
3 → 2 3 0.5В
→ 2 0.2В
2 → 2 2 0,8В
Bipotentiostat/Galvanostat µStat 400 (DropSens, Spain)
Potential range:
Scan rate:
- 2.0 V ~ 2.0 V
10 mV/sec
Working electrodes:
Reference electrode:
Counter electrode:
CONCLUSION:
CuFeS₂, FeS₂
Ag/AgCl (3M KCl)
Pt
Fig. 6. Eh-pH diagram of the Fe-S-O-H system.
Fig. 8. Eh-pH diagram of the system Cu-S-O-H
The electrochemical process occurring on the surface of minerals (chalcopyrite, pyrite) in an alkaline solution of sodium sulfide was studied and it was
established that as a result of oxidation on the surface of pyrite electrode at a potential (-0.5V, +1V) formed compounds are FeS, FeS2, FeOOH, and on
chalcopyrite electrode at potentials -0.7V, + 0.4V and +1V (vs Ag/AgCl), meta stable - compound of CuFe(1-x)S2 and copper formations of Cu2S, CuS and CuO are
formed, respectively. It is observed that in an alkaline (pH = 12) solution of sodium sulfide the current of the chalcopyrite electrode is more than that of pyrite
electrode. It indicates that chalcopyrite activity is higher in alkaline solution of sodium sulfide (pH=12). Based on the study findings a hydrophobicity and
selectivity of flotation process can be improved further establishing influencing factors of the given process.
CONTACT INFORMATION:
E-mail: prof., Erdenechimeg.D /Ph.D./ [email protected] ; Maralmaa.B /M.Sc./ [email protected]
Address: Main building of National University of Mongolia, Sukhbaatar district, Ulaanbaatar-13. P.O. Box 46A/272
Tel: +976 – 11 – 77307730 – 3206