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US20040226408A1 - Recovery of bioleaching microbes - Google Patents

Recovery of bioleaching microbes Download PDF

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Publication number
US20040226408A1
US20040226408A1 US10/756,906 US75690604A US2004226408A1 US 20040226408 A1 US20040226408 A1 US 20040226408A1 US 75690604 A US75690604 A US 75690604A US 2004226408 A1 US2004226408 A1 US 2004226408A1
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Prior art keywords
cells
bioleaching
extracted
microbial
membrane
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Abandoned
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US10/756,906
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English (en)
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Chris Du Plessis
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BHP Billiton SA Ltd
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Individual
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Assigned to BHP BILLITON SA LIMITED reassignment BHP BILLITON SA LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DU PLESSIS, CHRIS ANDRE
Publication of US20040226408A1 publication Critical patent/US20040226408A1/en
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
    • C12N1/02—Separating microorganisms from their culture media
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates generally to bioleaching and more particularly is concerned with a method for recovering bioleaching microbes.
  • Bioleaching is the term used to refer to the microbial oxidation of reduced iron or sulphide, contained in solid mineral particles, with the subsequent liberation of valuable metals associated with these particles.
  • the activated sludge process which is illustrated schematically in FIG. 1, was developed to address water pollution problems due to a dense population and advanced industry.
  • organic compounds in the water are biodegraded in an aerated reactor, mainly by bacteria, resulting in the build-up of a bacterial biomass in the reactor.
  • the inflow rate of fluid into the reactor should not exceed the rate at which the bacteria proliferate.
  • Such a scenario would result in the washout of bacteria from the reactor with an associated loss of biodegradation capacity for the incoming organic compounds.
  • the throughput of influent into such a reactor is therefore limited by the growth rate of the microbes in the reactor.
  • This limitation can be overcome, however, by separating the bacterial biomass (sludge) from the rest of the liquid.
  • This step is typically performed in a clarifier.
  • the relatively higher density of the sludge allows for gravitational settling with an overflow of treated effluent.
  • the concentrated sludge can then be returned to the aerated sludge reactor.
  • This process allows for the accumulation of sludge in the aerated reactor and is referred to as activated sludge.
  • the net effect of the process is that biomass, produced in the process of biodegrading the organic compounds contained in the influent, is not lost from the system, apart from a small amount that is purged to limit the accumulation of excess sludge. This results in a high concentration of biomass in the activated sludge reactor, which allows for a high liquid input flow rate and treatment efficiency of the reactor.
  • Microbial recovery of cells from bioleach bioractors is significantly more complex than the operation of a typical activated sludge plant used for wastewater treatment.
  • wastewater treatment two phases exist, viz the biomass sludge phase (biological solids phase) and the liquid phase.
  • three distinguishable phases exist viz the mineral solids particles (mineral solids), the microbial cell biomass (biological solids phase) and the liquid phase.
  • the microbial solids phase is not as uniform as in the case of activated sludge plants.
  • biological solids are either attached onto the mineral particle surfaces or freely suspended. Separation of the biomass phase from the other phases poses significant technical difficulties and challenges. These factors are a prohibitive barrier to the implementation of cell recycling, as in the activated sludge process, to bioleaching technology.
  • Schiraldi et al (Reference 1) describe a microfiltration bioreactor which achieves a high cell density in Sulfolobus solfataricus fermentation. Use is made of a hollow fibre microfiltration unit with the main aim being to improve yield in the growth medium by removal of toxic compounds in the growth medium. Cell concentration occurs in situ in the growth reactor and there is no mention of cell recycling as in the activated sludge-type system.
  • the medium does not contain solid mineral particles, nor is iron contained in any significant amount in the medium.
  • the medium contains yeast extract and other organic compounds and has a pH in the range of from 3.5 to 3.8.
  • the microfiltration unit is applied to a heterotrophic application.
  • the invention provides a method of recovering microbial cells in a bioleaching process which includes the steps of subjecting a slurry produced in a bioleaching plant to a solid/liquid separation process, and extracting microbial cells from the resulting liquid.
  • the microbial cells may be separated from metal in solution, in the liquid.
  • the microbial cells may be extracted by subjecting the liquid to a centrifugal process which may be carried out continuously, or on a batch basis.
  • the microbial cells are extracted by subjecting the liquid to a membrane filtration process.
  • the cells may be recovered by continuous concentration of the cells or the cells may be accumulated onto an inner surface of the membrane and are then removed in any appropriate way for example by back flushing or washing.
  • the microbial cells may be extracted using a plurality of extraction phases which are operated in series.
  • the bioleaching plant may include at least one bioleaching reactor, and typically includes a plurality of bioleaching reactors connected in series.
  • the method may extend to at least one of the following steps:
  • FIG. 1 illustrates an activated sludge system (prior art) which has already been described in the preamble to this specification
  • FIG. 2 is a block diagram representation of a method of recovering bioleaching microbes in accordance with the principles of the invention
  • FIG. 3 is a more detailed illustration of the process shown in FIG. 2,
  • FIG. 4 is a diagram of a ceramic membrane microfilter for use in the methods shown in FIGS. 2 and 3, and
  • FIG. 5 schematically depicts a centrifugal separation system which can be used in place of a ceramic membrane microfilter, in the method of the invention, to recover bioleaching microbes.
  • FIG. 1 depicts a typical activated sludge process and has already been referred to in the preamble to this specification.
  • FIG. 2 of the accompanying drawings is a flow chart representation of the method of the invention for recovering bioleaching microbial cells making use of a microfiltration membrane.
  • Bioleaching may be described as a process in which the bio-oxidation of ferrous iron and sulphides occurs in continuous culture agitated and aerated reactors, with the subsequent release of metals such as copper into solution. 2
  • metals such as copper into solution. 2
  • the metals of interest do not go into solution but are bio-beneficiated by the fact that the sulphides are oxidised, resulting in lower cyanide consumptions upon extraction of such metals from the remaining residue.
  • This process can take place in a single reactor or a train of several reactors in series.
  • a concentrate feed 10 which contains a desired metal such as gold or copper, which is to be recovered, is fed to a bioleaching process 12 .
  • a slurry 14 produced by the bioleaching process, is fed to a solid/liquid separation stage 16 .
  • the oxidised minerals solids residue 18 from the separation stage 16 is treated for disposal.
  • the liquid or supernatant 20 from the process 16 is subjected to a cell recovery step 22 which may be effected by making use of a centrifugal technique (see FIG. 5), or by making use of a membrane filtration process (see FIGS. 3 and 4), which separates the suspended cells 24 from the liquid 20 .
  • the recovered cells may be recycled to the process 12 , be stored (block 26 ), be used for inoculation purposes (block 28 ), or be used for bio-product production (block 30 ).
  • the metal remaining in the liquid from which the cells 24 are extracted is then recovered using a suitable process 32 which is known in the art e.g. solvent extraction or electrowinning.
  • FIG. 3 is a more detailed depiction of the method of the invention and, where applicable, like reference numerals are used to designate like steps or components.
  • the concentrate feed 10 is fed to a bioleaching plant 12 which includes a succession of bioleaching reactors designated 12 A, 12 B, 12 C, etc. which are connected in series.
  • a bioleaching reactor designated 12 A, 12 B, 12 C, etc.
  • the slurry effluent 14 from the bioleaching chain of reactors reports to a solids/liquid separation process 16 which typically is based on the use of a clarifier or thickener 16 A.
  • a flocculent agent may be added to assist in such separation.
  • the supernatant 20 then contains a suspension of remaining (non-attached) microbial cells.
  • the oxidized minerals solids residue 36 from this process is treated for disposal (step 18 ).
  • the retention time in the solids/liquid separation system should be sufficiently short to ensure ongoing viability of the microbial cells.
  • a variation of a gravitational solids/liquid separation step would be the use of a hydrocyclone or any similar process in which the gravitational selectivity and separation is induced or takes advantage of the relative density differences between the microbial cells and the minerals solids particles.
  • the supernatant 20 from the solids/liquid separation process, containing suspended microbial cells, is treated by using a membrane filtration process 22 to separate the suspended cells from the solution.
  • a membrane filtration process 22 to separate the suspended cells from the solution.
  • This may be effected in various ways.
  • the liquid 20 is passed into a ceramic microfiltration membrane 40 , which is shown in further detail in FIG. 4.
  • the membrane has a cylindrical wall 42 and is mounted inside a casing 44 .
  • the liquid 20 is pumped into an inlet 46 of the cell by means of a peristaltic pump 48 , or any similar device.
  • the pressure of the system which is a measure of the permeability of the membrane, is monitored by means of a gauge 50 .
  • Permeate 52 passes through the membrane wall and is collected inside the housing.
  • the permeate flow through the membrane wall is assisted by means of a vacuum induced inside the housing, around the membrane, by means of a peristaltic pump 54 or any similar device.
  • the level of the vacuum inside the housing is monitored by means of a gauge 56 .
  • the permeate 52 contains metals in solution and is directed to a known metal recovery process 32 , as has been described in connection with FIG. 2.
  • a flow meter 58 is used to provide a measure of the permeate flow rate from the casing 44 .
  • the cells 24 exit the membrane tube via an outlet 60 and are continuously recovered.
  • the rate at which the cells leave the membrane tube is measured by means of a flow meter 62 .
  • the flow rate is relatively high with a relatively low cell concentration. This situation is designated in FIG. 3 by means of a relatively large arrowhead 64 .
  • the flow rate is relatively low but the cell concentration is relatively high, as is indicated by means of a relatively small arrowhead 66 .
  • membrane units may be used in series to improve efficiency and in order to allow for sequential and automated back-flushing and membrane maintenance procedures to be implemented.
  • the membrane reactor, the solids/liquid separation system, and the solution entering and exiting the membrane reactor should preferably be maintained at a temperature sufficiently high to maintain metabolic activity of these cells.
  • the recovered concentrated cell suspension 24 could be used for any, or a combination, of the following:
  • the process of the invention could also be applied in a system where a step is introduced to remove attached microbial cells from solid mineral particles.
  • bioleaching process benefits can be achieved directly or indirectly from the recovery and recycling of cells to, and from, a bioleaching reactor plant:
  • any microbial adaptations which occur in the reactors would be retained and recycled. This would result in the eventual proliferation of any such mutated or adapted organism if such an adaptation provided the particular cell with a competitive advantage under the prevailing reactor conditions; and cells with various growth rate kinetics could be accommodated in the reactors.
  • the microbial growth rate is controlled by the hydraulic retention time. In such a reactor, at steady state, the microbial growth rate of the cells is equal to the dilution rate (reciprocal of the hydraulic retention time).
  • Microbes with a maximum specific growth rate less than the prevailing dilution rate would, therefore, be accommodated in such a reactor.
  • Microbes with a maximum specific growth rate greater than the prevailing dilution rate would, however, be lost (washed out) from the reactor even if such microbes have superior affinity for ferrous and/or sulphide (smaller half saturation constants for these substrates) or have other superior qualities beneficial in the bioleaching process.
  • Discrimination in the continuous culture process is, therefore, mainly based on growth rates at the prevailing conditions.
  • the microbial cell (biological sludge) retention time is separated from the hydraulic and mineral solids retention times. This allows for the accommodation of microbes with a greater range of maximum specific growth rates and, therefore, also of microbes with other beneficial bioleaching properties.
  • Effective monitoring of the membrane recovery system could include the following elements:
  • Membrane type Ceramic microfiltration membrane
  • FIG. 5 schematically illustrates a centrifugal based system which can be used in place of the membrane microfilter shown in FIGS. 3 and 4.
  • the supernatant 20 is directed into a centrifuge 70 which is spun at high speed and which separates the microbial cells from the remaining solution in the centrifuge.
  • the cells 24 are drawn from the centrifuge and are used in any of the applications which have been described.
  • Solution which is depleted of cells is treated (step 32 ) for metal recovery e.g. by means of solvent extraction or electrowinning.
  • the centrifugal separation system can be operated on a batch or continuous basis to achieve results which are similar to those obtained by means of the membrane filter.

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  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Genetics & Genomics (AREA)
  • Biotechnology (AREA)
  • Organic Chemistry (AREA)
  • Zoology (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Wood Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Microbiology (AREA)
  • Biomedical Technology (AREA)
  • Virology (AREA)
  • Biochemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Tropical Medicine & Parasitology (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Micro-Organisms Or Cultivation Processes Thereof (AREA)
  • Apparatus Associated With Microorganisms And Enzymes (AREA)
US10/756,906 2001-07-16 2004-01-14 Recovery of bioleaching microbes Abandoned US20040226408A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
ZAZA2001/5817 2001-07-16
ZA200105817 2001-07-16
WOPCT/ZA02/00110 2002-07-04
PCT/ZA2002/000110 WO2003008565A1 (en) 2001-07-16 2002-07-04 Recovery of bioleaching microbes

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US (1) US20040226408A1 (es)
EP (1) EP1406999B1 (es)
AP (1) AP1648A (es)
AR (1) AR036164A1 (es)
AT (1) ATE450599T1 (es)
AU (1) AU2002354965B2 (es)
CA (1) CA2452777A1 (es)
DE (1) DE60234601D1 (es)
WO (1) WO2003008565A1 (es)
ZA (1) ZA200309784B (es)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070169587A1 (en) * 2004-07-16 2007-07-26 De Kock Sanette H Optimization of Bioleaching Process

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113549551A (zh) * 2021-07-20 2021-10-26 深圳华大基因医院管理控股有限公司 一种生物用细胞反应器

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4732608A (en) * 1986-02-07 1988-03-22 Envirotech Corporation Method for biological processing of metal-containing ores
US4974816A (en) * 1986-02-07 1990-12-04 Envirotech Corporation Method and apparatus for biological processing of metal-containing ores
US5007620A (en) * 1986-02-07 1991-04-16 Envirotech Corporation Apparatus for biological processing of metal-containing ores
US5278069A (en) * 1992-02-14 1994-01-11 The Israel Electric Corporation Ltd. Bioleaching method for the extraction of metals from coal fly ash using thiobacillus
US6309547B1 (en) * 1996-04-15 2001-10-30 Western Environmental Engineering Company Anaerobic treatment process with removal of nonbiodegradable organic material

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
PE20020912A1 (es) * 2000-11-25 2002-10-19 Billiton Sa Ltd Produccion de bioproducto

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4732608A (en) * 1986-02-07 1988-03-22 Envirotech Corporation Method for biological processing of metal-containing ores
US4974816A (en) * 1986-02-07 1990-12-04 Envirotech Corporation Method and apparatus for biological processing of metal-containing ores
US5007620A (en) * 1986-02-07 1991-04-16 Envirotech Corporation Apparatus for biological processing of metal-containing ores
US5278069A (en) * 1992-02-14 1994-01-11 The Israel Electric Corporation Ltd. Bioleaching method for the extraction of metals from coal fly ash using thiobacillus
US6309547B1 (en) * 1996-04-15 2001-10-30 Western Environmental Engineering Company Anaerobic treatment process with removal of nonbiodegradable organic material

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070169587A1 (en) * 2004-07-16 2007-07-26 De Kock Sanette H Optimization of Bioleaching Process
US7494529B2 (en) * 2004-07-16 2009-02-24 Bhp Billiton Sa Limited Optimization of bioleaching process

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AR036164A1 (es) 2004-08-18
AP2004002954A0 (en) 2004-03-31
AP1648A (en) 2006-07-31
CA2452777A1 (en) 2003-01-30
AU2002354965B2 (en) 2007-10-04
EP1406999A1 (en) 2004-04-14
EP1406999B1 (en) 2009-12-02
ATE450599T1 (de) 2009-12-15
WO2003008565A1 (en) 2003-01-30
DE60234601D1 (de) 2010-01-14
ZA200309784B (en) 2005-01-27

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