Leaching kinetics of malachite in ammonium carbonate solutions
Purchase on Springer.com
$39.95 / €34.95 / £29.95*
Rent the article at a discountRent now
* Final gross prices may vary according to local VAT.
Leaching of malachite was conducted with ammonium carbonate as lixiviant and with temperature, lixiviant concentration, and particle size as variables. Two stages of reaction were found. In Stage I, the initial dissolution of malachite proceeds rapidly, but after about 10 pct reaction the rate is reduced by surface blockage due to the presence of a needle-structured intermediate, presumably Cu(OH)2. Subsequently, malachite and the intermediate dissolve concurrently. In Stage II, after 90 pct reaction, essentially all of the malachite has dissolved and only the intermediate remains. It dissolves in Stage II. The activation energy is 64 kJ/mole (15.3 kcal/mole) for Stage I and 75 kJ/mole (18 kcal/mole) for Stage II. The rate of reaction in Stage I is proportional to the reciprocal of particle size and is 0.8 order with respect to the concentration of ammonium carbonate. The structures of leaching residues were studied using a scanning electron microscope. The kinetic data (activation energy and entropy), particle size and concentration dependence, residue morphology, and general leaching behavior evident from microscopic monitoring during leaching were used to develop the geometric equation for leaching in Stage I. The equation, based on a heterogeneous reaction with geometric rate control, is: 1 - (1 - α1/3 = K01/r0/[(NH4)2C03]0.8 exp(-64,000/RT)t. It was deduced that initial steps in reaction were: (1) release of Cu2+ from malachite; (2) initial complexing with ammonia to form Cu(NH3)2+; and (3) subsequent complexing to produce Cu(NH3) 4 2+ which is stable in solution at pH 8.8, the buffered pH of reaction. Stage II appears to be a similar reaction except that the reaction obeys cylindrical geometry instead of spherical geometry as in Stage I.
- H. Brasseur:Zeit. Krist., 1932, vol. 82, pp. 11–26.
- L.S. Ramsdell and C.W. Wolfe:Am. Minerologist, 1950, vol. 35, pp. 119–21.
- A. F. Wells:Acta Cryst., 1951, vol. 4, pp. 200–04. CrossRef
- P. Suesse:Acta Cryst., 1967, vol. 33, pp. 146–51. CrossRef
- G. A. Kopylov and A. I. Orlov:Tr. Inst. Met. i Obogasch, Akad Nauk. Kaz. SSR II, 1964, vol. 82, p. 9.
- B.R. Benner and J.R. Roman:SME-AIME Trans., 1974, vol. 256, pp. 103–05.
- E. M. Semenishin, G. A. Aksel’rud, and S. V. Limarenko (USSR):Inzh-Fig. Zh, 1973, vol. 25, no. 1, pp. 150–51 (Russ).
- K.O. Bryden: M.S. Thesis, June 1975, Dept. of Metallurgical Engineering, University of Utah, Salt Lake City, UT.
- K. O. Bryden: Ph. D. Dissertation, June 1980, Dept. of Metallurgical Engineering, University of Utah, Salt Lake City, UT.
- F. Habashi and R. Dugdale:SME-AIME Trans., 1973, vol. 254, pp. 98–102.
- J. Halpern:J. Metals, 1957, vol. 9, no. 2, pp. 280–89.
- R. M. Garrels and C. L. Christ:Solutions, Minerals and Equilibrium, Freeman, Cooper and Company, San Francisco, CA, 1965, pp. 61–71.
- K.S. Pitzer:J. Phys. Chem., 1973, vol. 77, p. 268. CrossRef
- F. Habashi:Principles of Extractive Metallurgy, Gordon and Breach, New York, NY, 1969, vol. 1, pp. 130–37.
- M. E. Wadsworth: Second AIME Tutorial Symposium on Extractive Metallurgy, University of Utah, Salt Lake City, UT, December 1972, pp. 29–32.
- A. M. Bard:Chemical Equilibrium, Harper and Row, New York, NY, 1966, p. 129.
- Leaching kinetics of malachite in ammonium carbonate solutions
Metallurgical Transactions B
Volume 14, Issue 1 , pp 33-40
- Cover Date
- Print ISSN
- Online ISSN
- Additional Links
- Industry Sectors
- Author Affiliations
- 1. Laboratory of Mineral Ore Dressing, Catholic University of Louvain, Place St. Barbe, 2, B 1349, Louvain la Neuve, Belgium
- 2. Department of Metallurgy and Metallurgical Engineering, University of Utah, 412 Browning Building, 84112, Salt Lake City, UT