Borates bounty: lumps of colemanite at Eti
Maden’s Bigadic works
Boron is a relatively rare element and does not appear on Earth
in elemental form; instead, it is found as a mineral deposit in
the crystalline group known as ‘borates’ (oxides of
boron). These are distinguished by a structural framework
formed of polymerized boron-oxygen-hydroxyl tetrahedral or
triangles, which are linked to each other by means of
cations.
This group includes boric acid,
borax and others. Boron, with an atomic number of 5 and weight
of 10.81, is a trivalent metalloid element that has a covalent
bond like non-metals but with intermediate properties between
metals and non-metals. It occurs abundantly in the evaporative
ores borax and ulexite.
Boron’s position in the
periodic table would indicate a close relationship to
aluminium, gallium, indium, and thallium, but it is actually
much more similar to carbon and silicon in its chemical
properties. Elemental boron is used as a dopant in the
semiconductor industry, while boron compounds play important
roles as light structural materials, insecticides and
preservatives, and reagents for the chemical synthesis of
carbon.
Figure 1: Turkish boron sales and global market share
Figure 2: World boron production, 2009 (3.29m. tonnes)
Boron background
Boron compounds may have been known of for about 6,000 years,
starting with the Babylonians. The Egyptians, Chinese, Tibetans
and Arabians are reported to have used such materials.
The first European borax source was
discovered in 1777 at the hot springs (soffini) near Florence,
Italy, and became known as sal sedativum, with mainly
medical uses. It was the main European source from 1827 to
1872, at which date US sources replaced it. Boron was not
recognized as an element until it was isolated by Sir Humphry
Davy and by Joseph Louis Gay-Lussac and Louis Jacques in 1808
through the reaction of boric acid and potassium. Davy called
the element boracium. Jšns Jacob Berzelius
identified boron as an element in 1824. The first pure boron
was arguably produced by the US chemist W Weintraub in
1909.
Although the use of boron or its
combined form of borax
(Na2B4O7. 10H2O)
dates back to early times, it did not become of interest until
the twentieth century. Early uses of it were as a mild
antiseptic ore cleaner because of its detergent and
water-softening properties and as ceramic flux due to its
ability to dissolve metal oxides.
Nowadays, the usage of boron varies
from insulation or textile fibreglass, heat resistant glass,
detergent, soaps, personal care products, ceramics, agriculture
micronutrients to aircraft fuel and hydrogen storage due to the
following advantages. First, borates are safe. Used for
centuries, they pose no risk to people, animals or the
environment under normal handling and use. Second, they are
versatile. In some applications, there is simply no substitute
for borates.
Boron forms several commercially
important compounds. The most important boron compound is
sodium borate pentahydrate
(Na2B4O7•5H2O).
Large amounts of this compound are used in the manufacture of
fibreglass insulation and sodium perborate bleach. The second
most important compound is boric acid (H3BO3), which
is used to manufacture textile fibreglass and is also used in
cellulose insulation as a flame retardant. Sodium borate
decahydrate
(Na2B4O7•10H2O),
better known as borax, is the third most important boron
compound. Borax is used in laundry products and as a mild
antiseptic.
Boron could also play an important
role in the world’s move away from fossil fuels toward
greener energy. Hydrogen can be obtained from the pyrolysis and
hydrolysis of some borohydrides. In its usage in fuel cells,
boron compounds are considered the most promising candidates
among the metal hydrates for the safe storage of hydrogen which
is an impediment to the commercial use of hydrogen as fuel in
fuel cells. NaBH4 has been found to be a feasible material for
a portable and safe hydrogen gas generator.
Commercialisation of
NaBH4 has been performed by Millennium Cell as the
‘Hydrogen on Demand’ process. The production of
magnesium diboride (MgB2) can be given as another
attractive research interest for the usage of boron.
MgB2 is a simple metallic compound differing from
ordinary metallic superconductors due to such unique properties
as a relatively high-critical temperature (Tc) of 39K,
and the low cost of the starting materials. This makes
MgB2 a promising candidate for practical
applications, in comparison with low temperature
superconductors (LTS).
In combination B and N have many
similarities to carbon. Both carbon and boron nitride (BN) have
hexagonal (graphitic) and cubic (diamond) crystal structures.
Hexagonal boron nitride is a soft lubricious material while
cubic boron nitride is second only to diamond in hardness and
is commonly used as an abrasive. The most notable differences
between C and BN are color and electrical properties. Graphitic
carbon is black and electrically conductive while (h)BN is
white and electrically insulating.
These properties and other unique
performance characteristics are the reason why BN is valuable
in many applications. Ceramics and intermetallic composites
incorporate boron nitride in their formulations to enhance
performance characteristics. A partial list includes: SiC/BN
TiB2/BN, Si3N4/BN AlN/BN,
ZrO2/BN Al2O3/BN.
Table 1: Turkish boron reserves
| Boron mineral |
Reserve (m. tonnes) |
Share (% ) |
| Colemanite |
888 |
74 |
| Ulexite |
24 |
2 |
| Tincal |
288 |
24 |
Figure 3: Turkey’s domestic boron sales, 2000-2009
Turkish boron market
The most important boron bearings in the world are,
respectively, Turkey, the USA, and Russia. Large deposits of
boron reserves occur in southern California and in Turkey.
Turkey has approximately 67% of the world’s known reserves
base, with 1.2bn tonnes. The USA, Russia and Kazakhstan follow
Turkey with 7% share rates. The US deposits consist primarily
of tincal and kernite, while Turkish deposits are 70%
colemanite.
The borate deposits of Turkey occur
in western Anatolia, south of the Sea of Marmara, within an
area roughly 300km east-west by 150km north-south. The main
borate districts are Bigadic, Kestelek, Sultancayõr,
Emet and Kõrka (see map). These borate deposits
are generally enveloped by, or grade into, limestone or clay
stone.
Figure 4: Turkish boron sales by market (2009)
Turkey’s global role
Turkey has the largest and highest quality reserves and is the
world’s leading exporter of the mineral. In proportion to
its reserve share, Turkey has had a relatively stable position
in the boron market in the last five years. In 2009, Turkey
possessed 37% of the total world production on the
B2O3 basis. This makes Turkey a major
world producer of both concentrated and refined boron products.
The total sales amounted to 1.1m. tonnes.
The mined boron minerals of Turkey
primarily consist of tincal, colemanite and ulexite. The tincal
ore is concentrated at Kõrka while colemanite is mined
mainly in the Emet and Bigadic regions. In addition, a
relatively small amount of ulexite is also mined in the Bigadic
and Kestelek regions. The reserves and share rates of these
regions are given in Table 1.
Boron mining was started in Turkey
in 1861 by foreign companies. Later, mining exploitation rights
were transferred to the state sector, Eti Maden Works General
Management (Eti Mine). The Eti Mine was established in 1935
under the name of Etibank in order to utilise the natural
resources of Turkey.
The annual production capacities of
Eti Mine are 2.45m. tonnes concentrated boron and 1.277m.
tonnes boron chemicals, respectively. In recent years, the
trading strategy of Turkey has shifted from the marketing of
boron concentrate to value-added products. In 1998, the share
of boron concentrate in total trade was 53%. This rate had
decreased to 8% by 2009. Most of the concentrated boron is used
for boron chemicals production.
The production of boron concentrate
and chemicals is performed by five plants, namely; Emet,
Kõrka, Bigadic, Kestelek boron works and the
Bandõrma boron and acid plant works. The production
levels of these foundations are given in Table 2.
The main mining method at the most
important borate deposits throughout the world is the open pit
operation. However, at the Bigadi and Kestelek mines some
part of the deposits had been operated by underground methods.
Today, all are open pit mines. In the industrial application,
the upgraded minerals are widely-preferred to refined products
because they are cheaper and compatible. Most of the
commercially mined deposits have a simple beneficiation plant
which consists of crushing, hand sorting, screening, washing
and classification circuits.
Following years of strong growth,
in 2009 a sharp decrease was observed in demand for borates
owing to the effects of economic crises and economy growth rate
in 2008. The decrease in the consumption of boron in 2009 was
calculated at 51% for Europe and 33% for North America,
respectively. It is estimated that the consumption of boron
decreased to 2.9m. tonnes (26.3%) compared to the previous
year. However, in the second half of the year, the markets for
both textile-grade fibreglass and borosilicate glass recovered
and demand for borosilicate glass in LCD screens is expected to
have grown by 15% in 2010.
The world production of natural and
refined borates remained highly concentrated in Turkey and the
USA in 2009. The two countries provided total production of
around 75% of the world supply. The actual production of boron
was estimated at about 3.29m. tonnes. Turkey kept its leading
role (41%), and North America (USA 29%), South America (Chile,
Argentina, Peru, and Bolivia 18%) and finally Asia (China,
Russia, India 12%) followed Turkey in share rates.
Although the state still plays a
major role in industry, Turkey has a very energetic, productive
private sector. This makes Turkey a rapidly growing country
compared to other developing regions.
According to statistical data
released by the Eti Mine base on domestic boron sales between
1999 and 2009, the Turkish boron market can be characterised by
several highs and lows caused by the general economic condition
of the country, overall growth rate per capita, GDP and
industrial output.
The domestic boron sales graph
given in Figure 3 clearly indicates that the boron consumption
in the domestic market developed with an increasing industrial
production rate especially due to the driving force of the
ceramic and glass sectors from 2001 to 2004, and kept this
position up to 2006. But the trend reversed after this
relatively stagnant period, and a continued decline in
consumption was observed due to economic recession and the
results of the global economic crisis on the domestic market.
Boron sales reached their lowest value in 2009, corresponding
to 40,306 tonnes.
The estimated distribution pattern
for boron compounds consumed in Turkey in 2009 is given in
Figure 4. The glass industry (glass fibre, glass wool, and
borosilicate glass) had the highest consumption share at 41%.
This was followed by ceramics at 38%, soaps, detergents, and
bleaches at 3%, and agriculture, packaging, textiles and timber
preservation with a consumption rate of 19%.
Figure 5: Distribution of Turkish boron research projects by
area
Research & investment
The economy of Turkey is largely developed. The country is
among the world’s leading producers of agricultural
products, textiles, motor vehicles, ships and other
transportation equipment, construction materials, consumer
electronics and home appliances. Turkey has the world’s
seventeenth largest nominal GDP. However, the usage of boron
and boron end products in the domestic market is far from the
expected level.
Not only to boost the boron market
but also to overcome an observed weakness in science and
technological policies of Turkey, a new technological roadmap
has been implemented since 2003. The road map ‘Vision
2023’ has been implemented to:
-
Overcome a weakness in innovation;
-
Increase the competitive advantage in today’s global
market;
-
Connect with global research;
-
Invest in a knowledge based economy.
A released report consists of:
-
Assessment of the current status of Turkey in the field
of science and technology;
-
Assessment of the long term scientific and technological
developments in the world;
-
Identification of the strategic technologies required for
achievement of creative production;
-
Recommendation of policies aimed at development and/or
acquisition of designated technologies.
According to Vision 2023, the
foundation of a national boron institute (BOREN) and university
research centres have been completed in addition to an existing
technology development department of Eti Mine. This institute
and other research centres, and also researchers from different
universities, are focusing the investigation of new application
areas for boron and its compounds and are carrying out
exploration of new products as well as studies on the
improvement of product quality. Since 2003, BOREN has provided
financial support for 131 research projects, 64 of which were
completed successfully.
The main industrial outputs of
these projects were; the production or synthesis of boron
additive cement, boron additive ceramics, three-methyl borate,
Na-borehydrate, zinc borate, boron nitrate, fire retardants and
micro-feeders for agricultural applications. The distribution
of the completed projects according to related application
areas are given in Figure 5.
The usage of borates in ceramics
production, especially as an additive for frit
production due to its ability to dissolve metal
oxides goes back to historical times. The Chinese have
traditionally used boron mainly in the production of ceramics
and glassware. However, recent research studies performed by
the Boron Research Center, Osmangazi University, Turkey, show
that borax could also be used as an additive in the production
of ceramic bodies.
The laboratory and plant studies on
the production of terracotta and floor tiles show an increased
presence of borax compared to the standard mixture of clay, as
a co-fluxing material in the body. It considerably accelerates
the vitrification process and allows for better technological
properties for the firing regime involved with relatively lower
energy consumption due to the decreased firing temperature. The
increased demand for boric acid from Turkish ceramic producers
in recent years could be attributed to the practice of these
findings in commercial production.
Eti Mine has also continued its
investment and research activities to increase the recovery and
plant capacities of boron. The rehabilitation and investment
programme started in 2005 has mainly focused on the projects
related to increasing capacity. The construction and equipping
of the Bandõrma agri boron production plant, with a
capacity of 8,000 tpa and borax decahyrate/pentahydrate
production plant (80,000 tpa) in Kõrka can be given as
examples of completed projects in 2009.
Table 2: The production capacities and main products of Eti
Mine at its five sites
Conclusions
A frequently discussed forecast concerning the world’s
economic status for the next 20-30 years sees a shift away from
the dominant current production centres or economic powers to
the fast growing countries, having young and productive
populations such as China, Brazil, India, Indonesia, Mexico and
Turkey. It has been estimated that approximately 75% of the
total world production will be supplied by these emerging
economic nations.
Borates are an integral part of the
natural world. Plants and even humans are reliant on them; not
only as a nutritionally important part of their diet, but also
as an essential component of many products in everyday use. The
latest developments in materials science have tended to focus
on electrical properties. However, mechanical properties are
also of major importance and the contribution of boron to
improve the material properties in the production of such
materials continues to grow.
Turkey holds approximately a 67%
share of the total known world deposits. These boron reserves
are high in tenor and quality and are estimated as being
sufficient to supply world demand for the next 250-500 years.
Such facts improve Turkey’s position on the global
marketplace as both a raw and processed materials supplier and
combine with increased productivity due to implemented new
supporters on education and technological innovation.
Principal borate deposits in Turkey
Contributor: Prof. Haldun Kurama, Boron
Research Center, Eskisehir Osmangazi University, Turkey.
Adapted from a paper presented at the 3rd Liaoning Boron
Industry Exposition, 27-28 September 2010, Shenyang.