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American-Eurasian Journal of Agronomy 2 (2): 84-88, 2009
ISSN 1995-896X
© IDOSI Publications, 2009

Biomining - A Useful Approach Toward Metal Extraction
1

Mohd. Haris Siddiqui, 2Ashish Kumar, 3Kavindra Kumar Kesari and 1Jamal M. Arif
1

Department of Biotechnology, Integral University, Luck now, India
Department of Biochemical Engineering, Harcourt Butler Technological Institute,Kanpur, India
3
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India

2

Abstract: Biomining is the extraction of specific metals from their ores through biological means usually
bacteria. Although it is a new technique used by the mining industry to extract minerals such as copper,
uranium and gold from their ores but nowadays biomining occupies an increasinglyimportant place among the
available mining technologies. Today biomining is no longer a promising technology but an actual economical
alternative for treating specific mineral ores.Traditional extractions involve many expensive steps such as
roasting and smelting, which requires sufficient concentrations of elements in ores while low concentrations
are not a problem for bacteria because theysimply ignore the waste which surrounds the metals, attaining
extraction yields of over 90% in some cases.
Key words: Biomining % Microbial decomposition % Pyrite % Lixiviant % Thiobacillus thiooxidans %
Thiobacillus caldus % Leptospirillum ferrooxidans
INTRODUCTION

THE PROCESS

Our ability to harness the natural capability of certain
microbes to decompose a variety of mineral deposits is anold process that dates back to Roman times in the first
century BC and probably the Phoenicians before that
[1-2]. Those early miners used microbial activity to leach
copper from ore without being aware that microbes were
involved but now with increasing research trend in
mineral biotechnology our interest toward the phenomena
has grown up and has given some potential results which
bringthe revolution in mining industry.
As the world wide high grade ore reserves are
falling day at appalling rate as most are worked out
because of high metal demand, traditional techniques
like pyrometellury and chemical processings are becoming
more and more economically inviable. Micro organisms
bear a clear advange over it, as not only they offer a
economically viable option but is alsoclean technology.
Microbes such as bacteria and fungi convert metal
compounds into their water-soluble forms and are
biocatalysts of these leaching processes [3]. Additionally,
applying microbiological solubilisation processes, it is
possible to recover metal values from industrial wastes
which can serve as secondary raw materials. Now with the
gaining importance this mechanism is being usedto
recover metals such as gold, copper, iron, uranium.

Biological Tools: A variety of mineral oxidizing bacteria
readily found can easily oxidize iron and sulfur
containing minerals. These include the iron- and sulfuroxidizing Acidithiobacillus ferrooxidans (previously,
Thiobacillus
ferrooxidans),
the
sulfur-oxidizing
Acidithiobacillus thiooxidans (previously Thiobacillus
thiooxidans)and Acidithiobacillus caldus (previously,
Thiobacillus
caldus)
and
the
iron-oxidizing
Leptospirillum
ferrooxidans
and
Leptospirillum
ferriphilum[4-6].
Several species of fungi can be used for
biomining. Experiments have shown, that two fungal
strains
Aspergillus
niger
and
Penicillium
simplicissimum were able to mobilize Cu and Sn by
65% and Al, Ni, Pb and Zn by more than 95%[7].
Similiarly, ‘Phytomining’ is based on the tendency of
some plant species to bioaccumulate excessive
amounts of metals from their host rock. The plants,
called hyperaccumulators are grown on highly
mineralized soils or post-mine lands and their yield
(bio-ore) is used as a pure metal source [8-9]. Compared to
the bacterial mining, these technologies are not so
popular primarily because...
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