New process could unlock untapped US ilmenite supplies
Published: Friday, 07 July 2017
A pilot scheme in the USA, jointly funded by the state government of Minnesota and the University of Minnesota, has delivered pigment-grade titanium dioxide at up to 99.8% purity from large ilmenite deposits that were previously considered unusable.
A pilot scheme has delivered pigment-grade titanium dioxide
(TiO2) from the large ilmenite deposits in the US state of
Minnesota, which were previously considered unsuitable for
commercial use due to the presence of hard-to-remove
The Natural Resources Research Institute, part of the
University of Minnesota, announced on May 25 that high-quality
titanium dioxide had been extracted through a proprietary
process which is suitable for commercial application.
The pilot scheme, joint-funded by the Minnesota state
government and the University of Minnesota, has delivered
pigment-grade titanium dioxide at up to 99.8% purity, processed
from 10 tonnes of local ilmenite.
A band of ilmenite deposits runs along the northeastern edge of
Minnesota. There are at least 13 oxide-bearing bodies in the
Among these is Longnose deposit, owned by mining junior
American Shield Titanium Group, reported to be among the
largest and highest quality ilmenite deposits in the US, which
delivered the ilmenite used in the pilot.
Drilling at Longnose indicates about 58m tonnes ilmenite with
17% TiO2 content, according to the Minnesota Minerals
Coordinating Committee (MMCC).
Of the other two sites that have been defined, the Titac
deposit has around 45m tonnes at 15% TiO2, while the Water Hen
deposit has some 62m tonnes at 14% ilmenite, the MMCC said.
Exploitation of the deposits has been so far prevented by the
high proportion of magnesium oxide in the ore, which is hard to
remove and compromises the whiteness of the finished
But the pilot demonstration was able to produce high-purity
TiO2 through the use of proprietary hydrometallurgical
The process also delivers usable 98.5% pure iron oxide.
Speaking to IM, the NRRI initiative director George Hudak noted
that the process also left other minerals as byproducts, such
as vanadium and magnesium. These could potentially be extracted
Hudak said that the production system was a "closed loop",
meaning that, in theory, it could be carried out with little
"This process (...) appears to be very cost-effective and with
commercial potential," said American Shield boss Bill
The cost of developing a mine and mill on the Longnose site is
estimated at $170m, Ulland told IM.
Ulland said that the next step in exploiting the deposit would
be to find a partner to handle the extraction.
The region of Minnesota in which Longnose is found is already a
centre of iron oxide mining, and the reserve appears easily
minable, with a low sulphur content which does not create the
same pollution risks as in other nearby copper deposits.
"Access is not a problem (…) I don’t think
you could find a better place [for a deposit]," he said.