Global metal casting output reached 80.3m. tonnes in 2009, down
from 93.5m. tonnes in 2008, with the top three producing
countries - China (35.3m. tonnes), India (7.44m. tonnes)
and the USA (7.40m. tonnes) - representing 62% of global
production. In the traditional foundry hub of Western Europe,
Germany led the market with an output of 3.9m. tonnes.
| Forging ahead: production of iron for metal
casting. Ferrous products account for 83% of the
The data reported are from
production numbers provided by each nations metal casting
association for 2009, collated by the World Foundry
Organisation. Although production suffered falling volumes in
2009 - corresponding to lower demand for metal products in
end markets such as automobiles and construction -
preliminary data from 2010 indicates that casting output
increased last year, with output expected to reach 2007 levels
Production is segmented into the
categories of ferrous and non-ferrous castings (see Figure
1). Foundries within the ferrous casting industry produce
grey, ductile, malleable, compacted graphite iron and carbon
and low alloy, corrosion resistant, heat resistant, manganese
and other steel cast products. This segment accounts for 83% of
the market, while non-ferrous foundries - producing
copper-based alloys, aluminium, magnesium, zinc and other
non-ferrous metals - account for 17% of the metal casting
| Table 1: Favourable zircon properties for
| Source: TCMS
Of the ferrous metals, 49% of
production is grey iron, 38% is ductile iron, steel accounts
for 12% and malleable iron for 1.3%. Among the non-ferrous
metals, aluminium dominates with 82% of the total, copper
alloys account for 13%, followed by zinc at 4%, and magnesium
Despite grey iron accounting for
close to half of the ferrous casting industry, its global share
is shrinking. Over the last decade or so, grey iron production
has increased 9.3% while ductile iron production has climbed by
39.6% and steel production has boomed 50%. Grey irons
market share has also fallen owing to the growth of non-ferrous
casting output, which has increased by 41.1% since 1999 -
largely from higher aluminium casting output.
North American foundry materials
supplier HA International believes the growth for metal casting
is expected to be seen predominately in aluminium and magnesium
applications, adding: Iron and steel applications are
expected to remain flat.
Traditional markets such as
automotive, rail and construction continue to drive metal
casting production, with newer markets - such as wind
energy - growing to take a noticeable share, HAI
| Figure 1: World casting production by metal
| Source: Modern Casting
According to the American Foundry
Society, new proposed fuel economy standards will further
increase aluminium casting as the automotive industry moves
away from iron engine blocks, cylinder heads and differential
and suspension castings in passenger automobiles and light
This trend towards aluminium for
motor blocks and cylinder heads has led to conversion away from
green sand molding with phenolic urethane cold-box and hot-box
cores, HAI explained. For aluminium blocks, a precision
sand mold is prepared.
Precision sand refers to a molding
process to produce castings with low dimensional variation in a
bonded molding media (usually sand). Numerous cores are held
together in a flaskless package, and the internal passages and
external geometry of castings are produced without the use of a
traditional mold or pattern plate.
These technological and
material changes will continue to affect metal casting
facilities and cause significant change in the global supply
and demand of castings, HAI revealed.
The change to light metals in
automotive applications has caused the closure of many
operations and reduction in production capacity in iron casting
operations, while aluminium demand and supply numbers rise to
new peak levels in both die casting and permanent mold
operations, the company told IM.
| Figure 2: Global production of automobiles,
2010 (top 10 countries)*
| *provisional results
Source: International Organization of Motor Vehicle
These changing trends have affected
consumption of foundry raw materials, which include a number of
industrial minerals used as foundry sands and as additives in
the casting process (see panel).
The principal foundry sands are
chromite, olivine, silica and zircon; silica represents the
lowest cost and most widely used material. The remaining
minerals are demanded in niche applications; speciality foundry
minerals are applied in substrates to prevent expansion defects
in molding materials exposed to particularly stringent thermal
New substrates are being introduced
as certain mineral sands increase in cost and/or become scarce.
This is seeing products such as synthetic ceramic mullites,
graphite sands and andalusite sands - such as
Damrecs Kerphalite product - being offered
to the market.
One mineral that has seen significant price increases over the
last six months is chromite sand, which has been used in
foundries for over 50 years. Chromite has steadily expanded its
end market from manganese steel castings to a wide range of
ferrous and non-ferrous castings.
|Construction of Oregon Resources mineral sands
processing facility in Coos Bay, Oregon, USA. The plant
is scheduled to produce 75,000 tonnes of chromite
concentrate in 2011, in addition to smaller amounts of
garnet, ilmenite and zircon. Oregon Resources Corp.
The mineral is commonly used to
face large castings or thick sections and has gained popularity
over the use of olivine, owing to the latters
incompatibility with many synthetic binder systems. Similarly,
foundries have re-evaluated the minerals ability to
replace zircon sand as the latter has become difficult and
expensive to purchase.
Global consumption of chromite
foundry sand is around 700,000 tpa, with the foundry sector
representing less than 3% of the minerals market (the
bulk - over 90% - is diverted to metallurgical
markets primarily for ferrochrome).
South Africa is the worlds
largest chromite producer and an important supplier of foundry
grade sand, with companies such as Rand York SA and US group
Amcol International offering material from the countrys
Bushveld Igneous Complex - estimated to contain up to 70%
of the worlds chromite reserves.
Last year Amcol boosted the
countrys foundry supply capability with a $50m.
investment into the Ruighoek Chrome project, where it
established a processing facility and warehouse to supply its
Hevi-sand foundry product.
The facility allows Amcol to offer
tailor-made grades to the market, such as higher chrome content
and lower silicate levels - sized to the foundries
requirements - rather than a one size fits all
The facility is also an attempt to
help stabilise the chromite sands supply chain, which has
traditionally relied on just in time
deliveries - a challenging task for a market that is
dictated by the sharp demand swings of the metal casting
In fact, over the last three years
or so, price fluctuations and material availability have been
two of the key challenges for the chromite market, and this is
particularly true for South Africa at present; the country is
currently balancing tight availability with logistical
One producer told
IM: We are entering wage negotiations
and labour strike season again and in some cases labour is
looking for 20% increases - which is very unlikely -
but they will strike to force the mines and
|Figure 3: Zircon prices, 2009-2011*
| *Zircon, standard grade, bulk, FOB
Solid lines = top of range; broken lines = bottom of
| Figure 4: Chromite prices, 2009-2011*
| *Chromite, standard foundry, 46-47% Cr2O3, wet
bulk, FOB South Africa
Solid lines = top of range; broken lines = bottom of
In the past companies had huge
buffer stocks to take away some of the impact of labour talks,
but owing to destocking during the downturn and better than
expected demand for casting from late 2010 to present, the
countrys chromite stocks are inadequate, the producer
This delicate supply balance comes
at a time when the mineral is in high demand; zircon sand
prices have doubled over the last six months (see Figure
3) and those who can are turning to chromite, either as an
alternative source of supply or as a candidate for partial
Similarly, chromite has
increasingly benefitted from the burgeoning wind power market,
which depends on well-manufactured wind turbine blades to
function. Chromite sand can provide the kind of precision this
market requires - offering excellent opportunities for
chromite producers in Europe and North America, where the wind
power industry is focused.
In the long-term the chromite sands
market is addressing a number of key issues (see Table
2). Producers are increasingly aware of customer-specified
grades and are looking to improve grain integrity and reduce
silica content, which requires more focus on chromite
processing techniques. The influence of customer-specified
grades may also start to be seen through consolidation and
vertical integration of the chromite supply chain.
Environmental issues are also faced
by the foundry industry, with chromite consumers looking to
improve the packing density of the particles to reduce resin
consumption (not only lowering emissions but also reducing
resin costs). Likewise, new recycling efforts are being made to
re-use spent sands or extract chromium - also reducing
foundries disposal costs.
Zircons refractory properties make it an ideal material
for metal casting, with approximately 150,000 tpa of zircon
sand consumed in this market (see IM May 2011:
Zircon substitution - myth or reality?
The mineral is unique in that it is
not consumed in the casting process; allowing it to be recycled
to remove binders and separate other foundry sands. Despite
this benefit, the cost of zircon sand has forced many of its
consumers to find cheaper alternatives, such as chromite -
although, as discussed above, chromite has its own supply
Ceramics consultant Alister
MacDonald, director of Technical Ceramic Marketing Services,
estimates that chromite could substitute for zircon in up to
50% of foundry applications; and with zircon now costing four
to five times more than chromite, there will be increased
efforts to replace zircon - where possible.
Security of zircon supply is
more important than price for most foundry uses for
zircon, MacDonald told IM. As
zircon costs 4-5 times that of chromite, most people will have
switched already if they didnt need zircon.
The shift to cheaper
(inferior) alternatives will be forced upon users who cannot
secure zircon, he explained.
One chromite project looking to
bridge this gap is USA-based Oregon Resources Corp., which is
developing a suite of heavy mineral sands Ð chromite,
garnet, ilmenite and zircon - at its Coos Bay project in
Oregon, on the west coast.
Chromite is the flagship product of
the heavy minerals mix - with ORC and its parent company
Industrial Minerals Corp. looking to produce 75,000 tpa. But
the company is positioning itself as premium grade chromite
producer - offering an alternative to bauxite, mullite and
zircon - owing to the unique size and shape of its
chromite sand grains (see IM July 2010:
Foundries fire up a gear).
Industrial Minerals Corps
CEO, Philip Garratt, told IM: ORCs
sand has a rounded grain shape and narrow particle size
distribution, which allows the rounded grains to pack together
This provides increased
grain-to-grain contact and therefore increases the contact
points for the binder to form more binder bridges, he
During tests the company has
observed higher tensile strength for cores, improved heat
transfer, and an improved casting finish, Garratt
ORCs plant is currently being
commissioned and is planned to achieve capacity (at the first
year run rate) by July 2011, Garratt told IM,
with the first-year production of 600,000 tonnes ore expected
to produce: 75,000 tonnes of SpheriChrome chromite
concentrate; 10-15,000 tonnes of chromite grading >42%
Cr2O3; >12,000 tonnes of high-Fe
ilmenite; 3,700 tonnes of zircon; and 13,000 tonnes of
In addition, production of more
than 20,000 tonnes of aluminosilicates (kyanite, staurolite,
epidote) will be returned to the mine site pending integration
of additional product circuits, expected in 2012.
ORC revealed that HAI is the
exclusive North American distributor of SpheriChrome,
while German trading group Possehl will handle European
|Table 2: Chromite foundry sands market trends - past
| Source: Vincent Agnello, IM Chromite
Metal casting outlook
Confidence is returning to the foundries sector, with a number
of industrial mineral producers reporting positive market
conditions for their grades.
Stan Franey, commercial director of
Minelco Ltd, told IM that the company was
seeing healthy demand for its traditional market
regions of Asia and Europe, adding: Foundries are
expecting double digit growth, based on positive news flow from
IMCs Garratt concurred:
The global foundry market so far this year has improved
on the prior corresponding period, and there is strong demand
for all of our products.
Garratt warned that the sector was
yet to reach pre-crisis levels in its main markets, but that
metal casting was stronger primarily in Asia and South
He commented: The
opportunities for raw material supply are excellent for
producers located in the USA, or in locations that have a US
dollar cost base; these [producers] will benefit in the short
to medium term.
The source of the metal casting
sectors renewed confidence is largely owing to the motor
vehicle industry - the biggest end market for
foundries - which has seen better than expected demand
return from Q2 2010 to present.
Provisional results of global
automobile manufacturing in 2010, released by the International
Organization of Motor Vehicle Manufacturers (OICA), indicate
that just over 77.6m. units (both cars and commercial vehicles)
were produced in 2010 - a growth of 25.8% on 2009
Of the top ten producers (see
Figure 2), China led the group with an output of 18.3m.
units, followed by Japan with 9.6m. units, and the USA with
almost 7.8m. units.
Chinas growth in motor
vehicle production has occurred with astonishing speed; in 2009
the country produced 13.8m. units - representing a 48%
increase - despite poor economic conditions for the rest
of the world. The country followed this with an increase of
almost 33% in 2010.
While fiscal stimulus aid packages
failed to help western car manufacturers in 2009, these
traditional motor vehicle production hubs - Germany, the
UK and the USA - all posted significantly better results
This was particularly evident in
the USA, where auto manufacturing grew 35% - just
exceeding the countrys drop in production in 2009 (34%).
If the US auto market performs equally well this year, it will
climb to levels not seen since 2006.
In the USA, the annual Foundry
Management and Technology Business Outlook Survey of metal
casting executives, managers and operators was conducted in
October 2010, with the results noting an improvement in the
economy with noticeable acceleration.
Demand recovery was described as
starting in a modest and consistent fashion, followed by
acceleration, with 57% of participants saying they expected to
see increases in their production for 2011. However, there
remained a conservative view on increasing capital. Also noted
was the modernisation of China and India as a significant
impact to the global economy.
Within the top five industry
concerns, raw material costs, energy prices and imported
castings were listed; indicating that while metal casting
production had returned to the USA, China had exposed
weaknesses and inefficiencies with US capabilities.
However, when the quality and
delivery of the castings was considered, the real value of
castings showed the USA to be a viable producer, the survey
In recent months, much of the
concern has focused on prices increasing for key raw materials
such as chromite and zircon (see Figures 3 and 4), but
also including chemicals such as phenol, methanol and furfuryl
alcohol, HAI told IM.
The impact is seen throughout
key binding systems used in foundry, cold box, no-bake, acid
set and resin coated sand, the company said.
The main causes are related to
limited supply with increased demand as well as rising fuel
prices; and the outlook is for continued increases globally as
the foundry industry recovers.
While the increases have affected
the pricing structure for castings, all indications show that
the increases in raw materials have not affected overall
production levels: metal casting is on the up, and producers
will need to secure raw materials.
Acknowledgement: The author wishes to thank Keith
McLean and Lorena ONeill from HA International for
providing extensive information on metal casting
Foundry minerals at a glance
| Zircon usage by application (2008)
| Source: TZ Minerals International
| Chromite sands by market
| Olivine sands by application
| Source: Industrial Minerals HandyBook, 4th
| Silica sand end markets*
| *US markets
Chromite sand: used in foundries for over 50 years and
has steadily expanded its end market from manganese steel
castings to a wide range of ferrous and non-ferrous castings,
and is commonly used to face large castings or thick sections.
Improvements in product quality and consistency and the
incompatibility of olivine with many synthetic binder systems
have boosted chromites market penetration.
Pricing: $480-520/tonne for standard foundry,
46-47% Cr2O3, wet bulk, FOB South
Olivine sand: widely used in the casting of manganese
steels due to its basicity. The magnesium content of the
olivine enhances its bonding characteristics when used with
clays, reducing bentonite usage. It is also used in the
production of castings (particularly non-ferrous) that require
a fine surface finish as well as in core manufacturing. Olivine
has faced competition from chromite sands as producers have
improved the quality of their foundry grades and have benefited
from olivines incompatibility with acid-cured binders.
Pricing: 40-80/tonne ($59-114/tonne)
depending on sand size, FOB European port.
Silica sand: the principal foundry moulding material
owing to its widespread availability and low cost. Fine,
naturally bonded sands have traditionally been used in the
casting of aluminium, light copper alloys, and light grey iron.
Heavier, naturally bonded sands are used in the moulding of
large iron castings. Applications for all naturally bonded
products have declined in favour of blends of washed sands,
bentonites and other binders and additives, owing to better
control and customisation of product characteristics.
Pricing: $20-22/tonne for bulk material, FOB
Zircon sand: niche product that is capable of
withstanding long exposure to the highest casting
temperatures - typically between 1,550-1,650¡C for
certain low alloy and low carbon steels. Its unique
characteristics (such as refractoriness, low linear thermal
expansion, and chemical stability) make it an ideal non-silica
foundry sand. But high prices mean it is usually reserved for
the most specialised applications; such as facings for heavy
iron and steel castings poured at high temperatures, as mould
paints or washes to improve surface quality, high definition
cores, and shell casting and investment casting.
Pricing: $1,600-1,700/tonne for standard
material, bulk, FOB Australia.
Other sands: andalusite, bauxite, ilmenite, kyanite,
mullite, perlite, sillimanite, fused silica and
Bentonite: has good bonding characteristics and fast
green strength, good hot strength, high gel formation and low
permeability. It is used to bind green sands (such as olivine)
together during foundry molding and metal casting. Both calcium
and sodium bentonites are used in foundry applications,
although Na bentonite is more stable at high
temperatures - such as those encountered during casting of
steel, ductile iron, and medium-heavy grey iron. Ca bentonite
is more commonly used for detailed intricate castings, usually
with grey iron, ductile iron, and non-ferrous alloys.
Pricing: $90-115/tonne for foundry grade,
bagged, railcars ex-works Wyoming, per s.ton.
Graphite: is traditionally used in core and mold
washings and foundry ladles. Low quality flake graphite or
amorphous flake graphite can be mixed with other refractory
minerals and shaped to form crucibles, molds and ladles for
multiple metal types. Finely ground flake graphite or amorphous
graphite can also be used with other minerals to form foundry
facing or coating for molds - creating a smooth finish on
castings. Pricing: $2,500-3,000/tonne for
large flake, 94-97% C, +80 mesh, CIF.
Other additives: alumina (fused and white fused),
gilsonite, kaolin and mica.
The casting process
Casting is performed using disposable (non-permanent) or
reusable (permanent) molds. In non-permanent or disposable
molding, the mold is destroyed when the metal casting is
removed from the mold. The opposite is true for permanent
molds, where the mold is reused after the casting is
The finished mold may consist of
one or more parts (mold sections), such as the cope (top), drag
(bottom) and cores, which form internal passages or cavities in
the metal casting. Molds and cores are generally produced from
similar molding materials. In most cases, the main component of
these is silica sand bound with inorganic or organic
In high production foundries, molds
are produced on molding lines with cores produced using
core shooters or blowers that use
compressed air to facilitate filling of the core box with the
sand/binder mix prior to hardening.
The most important raw material for
disposable molds is quartz sand. Quartz (α-modification)
is the most common modification of silica. When heated,
α-quartz undergoes a transition to the β-quartz
modification at temperatures above 573ºC (1,063
This reversible transition is
accompanied by expansion of the crystalline lattice leading to
a drop in the density from 2.65 to 2.50 g/cm3. Due
to this quartz transition, heat cracks leading to
casting defects such as veining may arise when the
resin-bonded molds and cores are poured, depending on the
degree of compaction of the molding material, the weight and
temperature of the melt, and the cross-linking density of the
Different binder systems are generally used for specific
molding processes. Molds for ferrous casting traditionally have
mainly been produced using inorganic binders such as clay and
in a very few remaining cases, using cement or waterglass. The
use of bentonite clay, water and a carbon-producing substance
such as seacoal is referred to as green sand
molding, due to the fact that the binder never hardens or cures
and remains moist.