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Early mining of chromite was on a small-scale and was relatively
straightforward from outcrops or to shallow depths followed
by hand sorting.
With the increased demand, conventional open-pit mining and
mechanical underground mining became necessary. Underground
mining of stratiform deposits is most often required but can
be particularly difficult due to the narrow seam thickness (less
than 1.5m), weathering close to surface and faulting. Open-pit
mining is generally applied to the podiform ores at first but
this progresses to underground mining as deeper levels of the
deposit are reached. Weathering through serpentinisation and
faulting are often encountered.
Historically, there was sufficient high-grade metallurgical
ore to meet demand but with the rapid growth of the stainless
and other alloy steel industries, the much larger reserves of
the lower grade, higher iron, ores have had to be exploited.
Reserves and Resources
Reserves are defined as proven in-situ tonnages, while resources
are estimated additional tonnages.
- The United States Geological Survey states that world resources
of chromite exceed 11 billion tonnes, sufficient to meet world
demand for many centuries.
- South Africa and Zimbabwe hold about 90% of the world's chromite
reserves and resources, with South Africa having reserves of
about 3.1 billion tonnes and a further estimated resource of
5.5 billion tonnes.
- Zimbabwe has reserves of about 140 million tonnes with resources
of a further 1 billion tonnes. It is the only country to exploit
both stratiform and podiform deposits. The stratiform deposits
occur in the Great Dyke, approx. 550 km long and 11 km wide,
while the podiform deposits occur in the Selukwe and Belingwe
areas.
- Kazakhstan has podiform deposits in the southern Ural Mountain
region with reserves of 320 million tonnes and a further 320
million tonnes resource. The ores vary greatly in chromium content
and in Cr:Fe ratios.
- India's output is from podiform bodies on the east coast of
the state of Orissa. Its reserves are put at 27 million tonnes
with a further resource of 67 million tonnes.
- Finland has podiform deposits near Kemi in northern Finland.
Although the Cr2O3
content is very low, the ore has been successfully mined, concentrated
and smelted to ferrochromium, and then converted to stainless
steel on site. Reserves are given as 41 million tonnes and resources
as 120 million tonnes.
- In Brazil, production is concentrated in Bahia and Minas Gerais,
although chromite deposits have been identified in other states.
These are mainly stratiform deposits with reserves of 14 million
tonnes and resources of 17 million tonnes.
- China's chromium resources are contained in podiform and stratiform
deposits but are largely unknown in terms of possible reserves
and resources. There is a chromite mine in Tibet. Russia also
has mines in the Ural mountains with further developments above
the arctic circle.
- Other countries with smaller chromite deposits include Oman,
Iran, Turkey and Albania. Total reserves and resources of these
and others are 24 million tonnes and 538 million tonnes respectively.
World Production and Global Development
While demand for chromium alloys has been expanding by some
5% annually over the past decade, the output of chromite ore
followed closely with an average growth rate of 4.6% per annum.
However, the market performance showed an unusual pattern:
Between 1994 and 1999, chrome ore production stagnated whereas
from the year 2000 onwards, market volumes increased from 15
million tonnes to 24 million tonnes in 2008.
This substantial increase can be primarily explained from the
rapidly rising global stainless steel demand and production
in China, where local ferroalloy plants converted strongly rising
imports of chrome ore into chromium alloys.
In the year 2008, world chromite ore production stood at 24
million tonnes with the following breakdown: South Africa accounted
for 39% of production, whilst Kazakhstan and India provided
15% and 16% respectively. Brazil, Finland, Oman, Russia, and Turkey together contributed a further 21%, whilst some 11
smaller producer countries brought the balance of 9%.
Within the total volume of ore and concentrates produced in
2008, 95% were metallurgical grade, 2% chemical grade and the
balance of 3% were refractory and foundry grade.
World Chromite Ore Production in 2008
* Albania, Australia, China, Iran, Madagascar, Pakistan,
Philippines, Sudan, UAE, Vietnam & Zimbabwe
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