Collector-metal behaviour in the recovery of platinum-group metals from catalytic converters

Abstract

A commercial pyrometallurgical process for the extraction of platinum-group metals (PGM) from a feedstock slag was analysed with the use of a model based on computational fluid dynamics. The results of the modelling indicate that recovery depends on the behaviour of the collector phase. A possible method is proposed for estimation of the rate at which PGM particles in slag are absorbed into an iron collector droplet that falls through it. Nanoscale modelling techniques (for particle migration or capture) are combined with a diffusion-controlled mass-transfer model to determine the iron collector droplet size needed for >95% PGM recovery in a typical process bath (70 mm deep) in a realistic time-scale (<1 h). The results show that an iron droplet having a diameter in the range 0.1–0.3 mm gives good recovery (>90%) within a reasonable time. This finding is compatible with published experimental data. Pyrometallurgical processes similar to that investigated should be applicable to other types of waste that contain low levels of potentially valuable metals.

Get full access to this article

View all access options for this article.

References

Hennion

F. J

. Availability of precious metals from spent cata-lysts. In The platinum group metals—an in-depth view of the industry. 1983 IPMI seminar, Williamsburg, VA, U. S. A., 10-13 April, 1983 (Allentown: International Precious Metals Institute, 1983), 61–81.

Hanewald

R. H.

, Onuska

J. C.

and Schweers

M. E

. Recycling nickel, chromium and iron catalysts through the high temperature metals recovery process. In Queneau

P.B.

and Preston

R. D.

eds Third international symposium on recycling of metals and engineered mate-rials, 1995 (Warrendale, Pa: The Minerals, Metals & Materials Society, 1995), 371–8.

Mishra

R. K.

and Reddy

R. G

. Pyrometallurgical processing andrecovery of precious metals from autocatalysts using plasma arc smelting. In Precious metals 1986: Proc. 10th International Precious Metals Institute conference, Lake Tahoe, Nevada (Allentown: International Precious Metals Institute, 1986), 217–30.

Gibbon

, Harry

J. E.

and Hodge

. The plasma process for the recovery of the platinum metals from autocatalyst. Paper pre-sented at International Symposium on Plasma Chemistry-8, Tokyo, 1987. Paper D11-03.

Burnham

. F, Harry J. E and Gibbon A. Plasma arc furnaces. European Patent application 0 096 493 A2, 1983.

Saville,

. Process for the extraction of platinum group metals. U. S. Patent 4 685 963, 1987.

Reddy

R. G.

and Mishra

R. K

. Recovery of precious metals by pyrometallurgical processing of electronic scrap. In Precious metals 1987: Proc. 11th International Precious Metals Institute conference, Brussels (Allentown: International Precious Metals Institute, 1987), 136–46.

Benson

The recovery mechanism of platinum group metals from catalytic converters in spent automotive exhaust systems. Resources, Conservation and Recycling, 31, 2000, 359–65.

Allen

M. P

and Tildesley

D.J.

Computer simulation of liquids (Oxford: Clarendon Press, 1987).

10.

Israelachvilli

J. N

. Intermolecular and surface forces, 2nd edn (London: Academic Press, 1991).

11.

Rafii-Tabar

and Sutton

A. P

. Long-range Finnis-Sinclair potentials for FCC metallic alloys. Phil. Mag. Letters, 63, no. 4, 1991, 217–24.

12.

Brandes

E. A

. Smithell's metals reference book, 6th edn (Basingstoke: Butterworth, 1983).

13.

Urbain

. Viscosity estimation of slags. Steel Res., 58 no. 3, 1987, 111–6.

14.

Mills

K. A.

and Keene

B. J

. Physical properties of BOS slags. Int. Materials Reviews, 32, no. 1-2, 1987, 1–120.

15.

Ukanawa

A. O

. M558 radioactive tracer diffusion. In Proc. 3rd space processing symposium—Skylab results, 30 April-1 May 1974, Marshall Space Flight Center, Alabama, vol. I (Springfield, Va.: NASA, 1974) 425-56.