Se ha denunciado esta presentación.
Utilizamos tu perfil de LinkedIn y tus datos de actividad para personalizar los anuncios y mostrarte publicidad más relevante. Puedes cambiar tus preferencias de publicidad en cualquier momento.
Bio leaching
Group members
Mehwish nazeer, Kanza saleem, Nazish mehmood
m.Ishaq javaid
m.adil
Introduction
 Bioleaching is the simple and effective technology for
metal extraction from low grade ores and mineral
con...
History
 Copper recovery from mine waters in the Mediterranean
area 3000 years ago.
 The role of bacteria in bioleaching...
Features of organisms
involved
Single celled organisms
Chemosynthetic metabolism
Derive carbon dioxide, oxygen from atm...
Procedure
Bacteria perform the key reaction of regenerating the major
ore oxidizer, mostly ferric ion. This reaction takes...
Thiosulfate is also oxidized by bacteria to give
sulfate:
• S2O3
2-
+2O2+H2O 2⟶ SO4
2-
+2 H+
(sulfur oxidizers)
The ferr...
Mechanism involves in
bioleaching
Two processes are used in bioleaching:
 Direct bioleaching
 Indirect bioleaching
In direct bioleaching
In indirect method of bioleaching of
minerals bacteria produce strong oxidizing
agent which reacts w...
In direct bioleaching minerals which are
susceptible to oxidation undergoes direct
enzymatic attack by the microorganisms....
A: In direct mechanism
B: Direct mechanism
Commercial process of
bioleaching
Naturally occur bioleaching process is very slow.
For commercial extraction of metal by...
Slope leaching
In slope leaching the ore is finely ground and kept in large pile in a
slope which is subjected to continu...
Main factors affecting bioleaching
FACTOR
Physicochemical
Temperature pH and to keep ferric
Oxygen reactions
Microbiologic...
Benefits of bioleaching
 Simple
 Inexpensive
 Employed for collecting metals from waste and
drainages
 Use to extract ...
Disadvantages
Time consuming
(takes about 6-24 months or longer)
Have a very low yield of mineral
Requires a large open...
bio leaching
Próxima SlideShare
Cargando en…5
×

bio leaching

19.734 visualizaciones

Publicado el

this is about how we extract metal from microorganisms

Publicado en: Medio ambiente
  • Sé el primero en comentar

bio leaching

  1. 1. Bio leaching Group members Mehwish nazeer, Kanza saleem, Nazish mehmood m.Ishaq javaid m.adil
  2. 2. Introduction  Bioleaching is the simple and effective technology for metal extraction from low grade ores and mineral concentrate by the use of micro organisms.  Commonly used microorganisms are:  Mesophiles  Moderately thermophilic bacteria  extremophiles
  3. 3. History  Copper recovery from mine waters in the Mediterranean area 3000 years ago.  The role of bacteria in bioleaching was shown in 1947.  In 1950´s copper dump leaching.  In 1960´s the first industrial copper heap leaching operation.  First industrial gold bioleaching plant in 1980´s  Nowadays about 40 plants in industrial use for copper, gold, zinc, cobalt, uranium.
  4. 4. Features of organisms involved Single celled organisms Chemosynthetic metabolism Derive carbon dioxide, oxygen from atmosphere Requires acidic PH
  5. 5. Procedure Bacteria perform the key reaction of regenerating the major ore oxidizer, mostly ferric ion. This reaction takes place in the cell membrane of bacteria.  In the first step, disulfide is spontaneously oxidized to thiosulfate by ferric iron (Fe3+ ), which in turn is reduced to give ferrous iron (Fe2+ ): • FeS2+6 Fe3+ +3 H2O 7⟶ Fe2+ +S2O3 2- +6 H+ spontaneous  In second step Microorganisms catalyze the oxidation of ferrous iron and sulphur, to produce ferric iron and sulphuric acid: • Fe2+ + 1/4O2 + H+ ---> Fe3+ + 1/2 H2O • S + 3/2O2 + H2O ---> H2SO4
  6. 6. Thiosulfate is also oxidized by bacteria to give sulfate: • S2O3 2- +2O2+H2O 2⟶ SO4 2- +2 H+ (sulfur oxidizers) The ferric iron produced in reaction (2) oxidized more sulfide as in reaction (1), closing the cycle and given the net reaction • 2 FeS2+7O2+2 H2O 2⟶ Fe2+ +4SO4 2 +4H+ The net products of the reaction are soluble ferrous sulfate and sulfuric acid.
  7. 7. Mechanism involves in bioleaching Two processes are used in bioleaching:  Direct bioleaching  Indirect bioleaching
  8. 8. In direct bioleaching In indirect method of bioleaching of minerals bacteria produce strong oxidizing agent which reacts with metals and extract them from the ores.
  9. 9. In direct bioleaching minerals which are susceptible to oxidation undergoes direct enzymatic attack by the microorganisms. Direct bioleaching
  10. 10. A: In direct mechanism B: Direct mechanism
  11. 11. Commercial process of bioleaching Naturally occur bioleaching process is very slow. For commercial extraction of metal by bioleaching the process is optimized by controlling the PH, temperature, humidity, o2 and co2 concentrations. These processes are:  Slope leaching  In-situ leaching  Heap leaching
  12. 12. Slope leaching In slope leaching the ore is finely ground and kept in large pile in a slope which is subjected to continuous sprinkling of aqueous solution of microorganisms. The leach liquor collected at the bottom of the ore is processed further for metal recovery. In situ leaching In in situ leaching ore is subjected to bioleaching in its natural occurrence, aqueous solution of microorganisms is pumped through drilled passages with in the ore. The leach liquid collected at the bottom of the ore used for metal extraction. Heap leaching In heap leaching ore is arranged in heap and goes through the same procedure as in slope leaching. The aqueous solution containing microorganism works on the heap of ore and produces the leach liquor. The leach liquor is used for metal recovery.
  13. 13. Main factors affecting bioleaching FACTOR Physicochemical Temperature pH and to keep ferric Oxygen reactions Microbiological Microbial diversity culture Population density Metal tolerance EFFECT • affects leaching rate, microbial composition and activity • needs to be low to obtain the fastest leaching rates and to keep ferric iron and metals in solution •electron acceptor needed in chemical and biological oxidation •mixed cultures tend to be more robust and efficient than pure •high population density tends to increase the leaching rate •high metal concentrations may be toxic to meta
  14. 14. Benefits of bioleaching  Simple  Inexpensive  Employed for collecting metals from waste and drainages  Use to extract refines and expensive metals which is not possible by other chemical processes  no poisonous sulfur dioxide emissions as in smelters  no need for hi pressure or temperature  ideal for low-grade sulfide ores  Environment friendly process
  15. 15. Disadvantages Time consuming (takes about 6-24 months or longer) Have a very low yield of mineral Requires a large open area for treatment May have no process control High risk of contamination Inconsistent yield because bacteria cannot grow uniformly

×