Chemical Engineering November 2012 - 10

CHEMENTATOR
(Continued from p. 9)
Microbial processing of ore
E
xtraction of metals, such as lithium, from
laterite ores is usually carried out through
solubilization of metals by acids, such as
sulfuric and hydrochloric acids. However,
substantial metal recoveries from laterites
have been achieved only through thermal
pre-treatment of laterites, using high concentrations
of acids at high temperatures.
Microbial processing of laterite ores at
ambient conditions can reduce acid and energy
consumption.
Microbial processing of laterites for nickel
extraction has been extensively studied
using several acid-producing fungal species.
However, there are major drawbacks when
using fungi, such as the cost of microbial
nutritional substrates required for organic
acid production and excess production of microbial
biomass with relatively poor yield of
metal values.
Now a team from the Institute of Minerals
and Materials Technology (www.immt.
res.in), and the Regional Center of Central
Tuber Crops Research Institute (both Bhubaneswar,
India; www.ctcri.org), led by professor
Lala Behari Sukla, has successfully
extracted nickel through the bacterial reduction
of laterite chromite overburden (COB)
at Sukinda Valey in the state of Odisha.
The Sukinda Valley is one of the major
chromite reservoirs in the world and the
only known deposit of nickel in India.
To recover nickel embedded in the goethite
[Fe(O)OH] matrix the team used Acidithiobacillus
ferrooxidans, which reduces
the ferric iron in goethite by using elemental
sulfur as an electron donor.
The microbial processing experiments
showed that up to 41% nickel extraction was
achieved, at anoxic condition in 18 days from
COB (1% nickel grade) at 5% pulp density.
The process was carried out without any
thermal pre-treatment or activation of COB
prior to microbial processing.
cost-effective than the corrosion
inhibitor molybdate, GE says.
FoodPro ST products use a
blend of organic corrosion inhibitors,
phosphates, polymeric dispersants
and a wetting agent,
and are designed specifi cally for
food sterilization equipment. GE
says in tests with its products
and alternatives, the FoodPro
ST chemicals offered equal or
better levels of corrosion and
scale inhibition than current
molybdate-based products without
heavy metals.
CHP & CO2 capture
GE (Fairfi eld, Conn.; www.
ge.com) recently unveiled the
fi rst combined heat and power
(CHP) system at a commercial
greenhouse. The system captures
CO2 and uses it to feed
tomatoes during daylight photosynthesis.
The cogeneration
system is located in Camarillo,
Calif. at the Houweling Tomato
greenhouse. It provides 8.7 MW
of electrical power and 10.6
(Continues on p. 12)
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Chemical Engineering November 2012

Table of Contents for the Digital Edition of Chemical Engineering November 2012