Sulfur content reduction of iron concentrate by reverse flotation

ABSTRACT

In this study, the desulphurization of iron ore concentrate using reverse flotation was investigated. In this paper first, behavior of the flotation of both pure – pyrite and iron oxides-pyrite with xanthate has been examined based on micro-flotation results and zeta-potential measurements. Then, an effort has been made to investigate the effect of pH, chemical reagent dosages, impeller speed, pulp density, flotation time and conditioning time parameters on desulphurization of actual iron ore concentrate using lab-scale mechanical flotation cell. Results of zeta-potential measurements displayed that iso-electric points (IEP) for pure and iron oxides-pyrite were around pH 7 and 8, respectively. Based on the micro-flotation results, the recoveries were highly dependent on pH. Both pyrite types showed high recoveries at pH 4.75 to 8, but in the flotation of iron oxides-pyrite, partial depression was found in the pH range of 6–7. The presence of iron ions in solution considerably depressed iron oxide-pyrite flotation in the pH range of 2.5–3. Recovery of both pyrites decreased dramatically when going from pH 10, due to the formation of iron hydroxides and the instability of dixanthogen. According to the data obtained from batch flotation tests, the maximum recovery of total sulfur was achieved when the operational parameters were set to the PAX dosage 200 gr/t, MIBC dosage 150 gr/t, CuSo₄ 75 gr/t, impeller speed 1500 rpm, pH 7.5, flotation time 7 min and pulp density 30%. With these optimum parameters, final concentrate with the grade of 69.48% Fe and 0.1% S was obtained.

KEYWORDS:

• Flotation
• desulphurization
• pyrite
• iron ore concentrate
• zeta potential
• xanthate
• optimization

Acknowledgments

The authors would like to acknowledge and the support of the Golgohar Iron Ore Complex and Steel Research Institute for this research.

Conflict of Interest

The authors declare that they have no conflict of interest.

Additional information

Notes on contributors

Fardis Nakhaei

Fardis Nakhaei was born in Iran, in 1986. He received the PhD degree of mineral processing in Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Iran in 2018. His research activity is on the modelling and control for the mineral processing processes.

Mehdi Irannajad

Mehdi Irannajad is an associate professor in Department of Mining & Metallurgical Engineering, Amirkabir University of Technology, Iran. His research interests are the mineral processing and process mineralogy.

Sima Mohammadnejad

Sima Mohammadnejad received the PhD degree of mineral processing from the University of Melbourne, Australia, in 2014. She is an assistant professor in Tarbiat Modararres University, Iran. She has extensive experience in the characterization and processing of ores, combining her knowledge and expertise in both mineralogy and processing.

Amir Hajizadeh Omran

Amir Hajizadeh Omran received the M.Sc. degree of mineral processing from the Shahid Bahonar University of Kerman, Iran, in 2011. He is a researcher in Golgohar Iron Ore and Steel Research Institute, Sirjan, Iran.