Bio-oxidation process and apparatus

Inactive Publication Date: 2006-01-03
RHODES MIKE +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0014]Surface aerators such as paddle aerators may be used to break liquid surface and assist in entrainment of gas such as air in the bulk reaction slurry. Reactor configuration may be varied to maximise aeration.

Problems solved by technology

Primary among these is the high power consumption and high capital cost encountered in employing bacterial oxidation reactors agitated by impellers.
Although proposals have been made to employ diffusion means to maintain particles in suspension, notably in Envirotech U.S. Pat. Nos. 4,728,082, 4,732,608, 4,968,008, 4,974,816 and 5,007,620, it is uniformly recognised that there is a need to provide some mechanical means, for example in the form of a rake to ensure that significant quantities of solids are not deposited on the floor of the reactor vessel, reducing reactor efficiency.

Method used

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  • Bio-oxidation process and apparatus
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  • Bio-oxidation process and apparatus

Examples

Experimental program
Comparison scheme
Effect test

example a

[0080]Inert Material

[0081]A trial was conducted on an inert mineral used to duplicate sulphide ores and concentrates.

[0082]A 10% weight percent slurry with a sizing of 90% passing 16 micrometers was maintained in uniform suspension in a tank with fine air bubbles injected from a close packed array of membrane disc diffusers of EPOM synthetic rubber commercially available from Nopol's under the trade mark PIK300. The diameter of the disc is 304 millimeters at the base of a 1.4 meter diameter by 4 meter high tank. The height of tank is similar to that used in commercial practice.

[0083]Air flows of at least 2.4 Nm3 / h / diffuser was required to prevent settling of solids. The air flow rates required were within the manufacturer's recommended operating range.

[0084]Solids that settled because of a reduction or disruption in air flow were resuspended when the air flow was re-established at 2.4 Nm3 / h / diffuser or higher.

[0085]These results showed that a typical ground sulphide concentrate with...

example b

[0087]Leaching of Refractory Gold Sulphide Concentrate

[0088]A sample of gold concentrate containing arsenopyrite and pyrite was ground to a size such that 80% of the particles were less than 15 micrometers in diameter.

[0089]The bio-oxidation reactor, constructed from conventional acid resistant material, had a volume of 200 liters and was provided, at its base, with a membrane diffuser as described in Example A. Air was supplied to the diffuser at a rate which maintained the ground solids in suspension. No other agitation was used.

[0090]The ground concentrate was mixed with water to produce a slurry at 10% solids on a weight to volume basis. Sulphuric acid was added to the slurry to obtain an acidity level of pH 1.2. Approximately five liters of an inoculum slurry containing a mixture of mineral concentrate and moderately thermophilic bacteria was added to the slurry in the reactor. Thereafter a mixture of nutrients comprising hydrated magnesium sulphate, potassium orthophosphate, a...

example c

[0099]Leaching of Copper Concentrate

[0100]A sample of copper concentrate containing chalcopyrite (and designated “CP1”) was ground to a size such that 80% of the particles were less than 10 micrometers in diameter. Again, the bio-oxidation reactor had a maximum volume of 200 liters and a membrane diffuser, as described in Example A, was installed at the base. Air was supplied at a rate to maintain the ground solids in suspension and maintain oxygen requirement of the bacteria. No other agitation was employed.

[0101]The ground concentrate was mixed with water to produce a slurry at 5% solids on a weight to volume basis. Sulphuric acid was added to the slurry to obtain an acidity level of pH 1.2. Approximately 5 liters of an inoculum slurry containing a mixture of mineral concentrate and moderately thermophilic bacteria was added to the slurry in the reactor. Thereafter, a mixture of nutrients comprising hydrated magnesium sulphate, potassium orthophosphate, and ammonium sulphate was a...

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Abstract

Disclosed is a process and apparatus for conducting bio-oxidation processes for the extraction of metals from metal containing materials in which aeration means, preferably a diffuser means, is employed within a bio-oxidation reactor to maintain bacterial viability and suspension of metal containing materials by introduction of an oxygen containing gas to a non-mechanically agitated reactor.

Description

[0001]This application claims the benefits under 35 U.S.C. § 365 of PCT International Application No. PCT / AU99 / 00917 filed 22 Oct. 1999 entitled “Bio-Oxidation Process and Apparatus” which was published in English on 25 May 2000 having International Publication No. WO 00 / 29629, and which claims priority to Australian Patent No. AU PP 7180 filed 18 Nov. 1998.FIELD OF THE INVENTION[0002]This invention relates to bio-oxidation processes and reactors for the liberation of metals from minerals, especially sulphides, containing them.BACKGROUND OF THE INVENTION[0003]Metal containing minerals, especially metal sulphides, may be oxidised using specific types of micro-organism, especially bacteria in a bioextraction, particularly a bio-oxidation process. Oxidation of sulphide minerals may be used to put the metals into solution, from for example iron, copper, zinc, nickel and cobalt sulphides, or to release precious metals, such as gold, silver and platinum, encapsulated in metal sulphides, p...

Claims

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Application Information

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IPC IPC(8): C22B3/18C22B3/02
CPCC22B3/02C22B3/18Y02P10/20
InventorRHODES, MIKEMILLER, PAUL C.WINBY, RICHARD
OwnerRHODES MIKE