Specialized metallurgical processes – compositions for use therei – Processes – Free metal or alloy reductant contains magnesium
Patent
1993-11-15
1995-07-04
Rosenberg, Peter D.
Specialized metallurgical processes, compositions for use therei
Processes
Free metal or alloy reductant contains magnesium
423DIG17, C22B 1100
Patent
active
054296595
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The present invention relates to a process for the treatment of metal containing materials by bacterial oxidation.
FIELD OF THE INVENTION
It is known that recovery of metals especially precious metals and base metals from refractory sulphide materials can be enhanced by bacterial oxidation or leaching. The bacterial treatment subjects the sulphide material to a pre-oxidation. The refractory sulphide materials can take a wide variety of forms including mineral sulphides, carbonaceous sulphide ores, sulphide flotation concentrates, sulphide gravity concentrates, sulphide tailings, sulphide mattes and sulphidic fume.
The precious metals and some base metals remain in the oxidised solid residue and can be recovered by conventional carbon in pulp or other chemical leaching processes. Some base metals such as copper, zinc and nickel go into solution and may be recovered directly by conventional solvent extraction and electrowinning.
In the past, bacterial oxidation of precious or base metal containing sulphide materials has typically been conducted using bacteria of the Thiobacillus species. However, the Thiobacillus species can only operate at temperatures up to about 40.degree. C. Further, the oxidation effected by Thiobacillus bacteria is an exothermic reaction and it is sometimes necessary to cool the process reactors to prevent the temperature exceeding that at which the Thiobacillus bacteria can operate.
SUMMARY OF THE INVENTION
The present invention provides a process for the bacterial oxidation of metal containing sulphide materials using thermotolerant bacteria which can operate at higher temperatures than conventional Thiobacillus bacteria. In accordance with one aspect of the present invention there is provided a process for recovering metals from particulate refractory precious or base metal containing sulphide materials which comprises contacting the sulphide material with an aqueous solution containing a thermotolerant bacteria culture (as herein defined) capable of promoting oxidation of the sulphide material at a temperature in the range from 25.degree. to 55.degree. C., separating the oxidised residue from the aqueous liquid and treating the oxidised residue and/or the aqueous liquid to recover metal therefrom.
DESCRIPTION OF THE INVENTION
The thermotolerant bacteria used in the present invention are as described in "Thermophiles General, Molecular, and Applied Microbiology" edited by Thomas D. Brock and published by John Wiley & Sons (1986). In Chapter 1 of this publication, there is illustrated in FIG. 1(b) a graph showing that thermotolerant bacteria grow at temperatures lower than those preferred by moderate and obligate or extreme thermophiles.
In the context of the present invention, a thermotolerant bacteria is one which has an optimum growth temperature of 40.degree. to 45.degree. C. and an operating temperature of 25.degree. to 55.degree. C. Preferably, the aqueous solution used in the process of the present invention is acidic. It has been found that the optimum acidity of the aqueous liquid for growth of the thermotolerant bacteria culture used in the present invention is in the range from pH 1.3 to 2.0, whilst the optimum acidity of the aqueous liquid for operation of the process of the present invention is in the range from pH 0.5 to 2.5.
The bacterial oxidation step of the process of the present invention is conducted in the presence of nutrients which are typically dissolved salts of nitrogen, potassium and phosphorus. The nutrients may already be present in the aqueous liquid or they may be added thereto. The nutrient materials promote the growth of the thermotolerant bacteria.
It is preferred that the thermotolerant bacteria be acidophilic in view of the pH conditions under which the process of the present invention is preferably conducted. Further, the thermotolerant bacteria used in the process of the present invention are typically aerobic and thus the aqueous liquid is preferably aerated during the operation of the process to ensure that there is an ade
REFERENCES:
patent: 4729788 (1988-03-01), Hutchins et al.
patent: 4740243 (1988-04-01), Krebs-Yuill et al.
patent: 4752332 (1988-06-01), Wu
patent: 4822413 (1989-04-01), Pooley et al.
patent: 4987081 (1991-01-01), Hackl
patent: 5030426 (1991-07-01), Bowers-Irons et al.
patent: 5236677 (1993-08-01), Torres-Cardona
patent: 5244493 (1993-09-01), Brierley
patent: 5246486 (1993-09-01), Brierley
Barrett Jack
Budden Julia R.
Hughes Martin N.
Poole Robert K.
Spencer Peter A.
Bac Tech (Australia) Pty Ltd.
Rosenberg Peter D.
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