Bulk precipitation of nickel and cobalt from sulphate leach liquor by CaO pulp

Abstract

The research work in the present paper determined the conditions at which nickel and cobalt can be recovered, as easily filterable precipitates, from leach liquors, which are produced by sulphuric acid leaching of nickel oxide ores at atmospheric pressure. Nickel and cobalt were precipitated as hydroxides at pH = 8·7, using CaO pulp as a neutralising agent, by 99·9 and 99·8% respectively. At this pH value manganese and magnesium, which were contained in the leach liquor, were precipitated, having a concentration of about 2·6 and 4·7% respectively in the final mixed precipitate. Statistical design and analysis of experiments were used in order to determine the main effects and interactions of the precipitation factors, which were the pH value at equilibrium and temperature. The characterisation of the produced mixed precipitate was carried out by X-ray diffraction, thermogravimetric/differential thermal analysis (TG/DTA), scanning electron microscopy and particle size distribution analyser. The main mineralogical phases of the precipitate after drying at 110°C were nickel hydroxide and bassanite (CaSO₄.0·5H₂O).

Keywords

NICKEL COBALT PRECIPITATION CAO PULP

Get full access to this article

View all access options for this article.

References

Agatzini

and Dimaki

: ‘Recovery of nickel and cobalt from low-grade nickel oxide ores by heap leaching with dilute sulphuric acid at room temperature’, Greek Patent No. 1001555, 1991.

Agatzini

, Oustadakis

and Zafeiratos

: ‘Removal of aluminum and chromium from nickel—cobalt sulphate solutions’, Greek Patent No. 1003419, 1999.

Tsakiridis

P. E.

and Agatzini

S. L.

:. Hydrometallurgy, 2004, 72, 269–278.

Agatzini

and Karidakis

: ‘Production of a magnesium hydroxide containing mixture suitable for use as a filler in polymers and as an additive in cement’, Greek Patent No. 1003693, 2000.

Agatzini

and Dimaki

: Method for extraction of nickel and/or cobalt from nickel and/or cobalt oxide ores by heap leaching with a dilute sulphuric acid solution, prepared from sea water, at ambient temperature’, Greek Patent No. 1003569, 2000.

Virnig

M. J.

and MacKenzie

: ‘Process for the recovery of nickel’, US Patent No. 5976218, 1999.

Jones

D. L.

: ‘Process for extraction of metal from an ore or concentrate containing nickel and/or cobalt’, US Patent No. 6171564, 2001.

White

D. T.

: ‘Selective precipitation of nickel and cobalt’, US Patent No. 6409979, 2002.

Sist

and Demopoulos

G. P.

: JOM, 2003, 55, (8), 42–46.

10.

Tadakazu

, Hideki

, Ayumu

and Mikiko

: Proc. 14th Int. Symp. on ‘Industrial crystallization’, (ed. Garside

), 158–165; 1999, Cambridge, IChemE.

11.

Freeman

H. M.

(ed.): ‘Standard handbook of hazardous waste treatment and disposal’: 1989, New York, McGraw-Hill.

12.

Box

G. E. P.

, Hunter

W. G.

and Hunter

J. S.

(eds.): ‘Statistics for experiments’: 1978, New York, John Willey.

13.

Mackenzie

: ‘Differential thermal analysis’, Vol. 2; 1972, London, Academic Press.