Refractory dolomite emerges from the shadow

RHI’s subsidiary Dolomite Franchi is one of the
few refractory dolomite producers with 0.5m. tpa
dolomite mined in the north of Italy


Being directly dependent on the steel industry, refractory dolomite was significantly impacted by the financial downturn which led to a necessary downsizing of the installed capacities.

About 20% of dolomite produced is used for specific applications in the steel and cement industries, the main 80% being used for construction. There are also some applications for agriculture as soil correction, but it represents a very small portion (see Dolomite at a glance).

Since the major part of dolomite goes into the steel industry, the ups and downs of the steel sector are reflected in the development of dolomite and demand shows a parallel curve to standard magnesia-based refractories.

During the crisis, intermittent operations reduced demand as people stopped using dolomite owing to the risk of hydration if the kiln was stopped for a long period of time.

Even if “the industry is not back to business as usual,” as head of RHI-owned Dolomite Franchi Spa plant Alessandro Romano told IM, stainless steel markets have shown some pick up, driving up dolomite consumption.

Similarly to many other branches, the dolomite industry has strongly concentrated on environmental issues. Whether it was new ecologic binders for shaped dolomite refractories or modernised plant equipment in order to minimise gas, dust and noise emissions, all these measures made dolomite refractories a very advanced state-of-the-art product for the steel industry.

Meanwhile some of the strict measures could be released again. But the industry is not yet back to the bright days of the 1990s.

However, the refractory world is opening its eyes for this type of raw material and specifically to the products made with it. It has very interesting advantages like good and reliable performance in addition to attractive lower costs.

“The tendency is to have an increase in the consumption,” Mauricio Pinho, Magnesita Refrat‡rios SA’s raw materials global director, explained to IM.

Dolomite production, particularly for aggregates, is extremely widespread but refractory grade dolomite production is relatvely limited.

World refractory dolomite producers include Magnesita Refrat‡rios SA (USA, China, Belgium, France and Germany), Carmeuse North America, USA, Calcinor SA, Spain, Vardar Dolomite, FYR Macedonia, and RHI AG’s subsidiary Dolomite Franchi in Italy.

Dolomite Franchi

Italy’s Dolomite Franchi Spa, 100%-owned subsidiary of RHI AG since 2007, produces high grade dolomite for secondary metallurgy in Brescia, Lombardia, in the north of Italy. Refractory products based on dolomite are used almost exclusively in steel production. Because of their extremely low rate of impurities, the bricks are used primarily in ladles (90%). They are also used in AOD converters (10%); monolithics are used as hearth ramming and repair mixes in the electric arc furnace (50%) and for the lining of ladles and converters (50%).

Founded in 1919, Dolomite Franchi started production of dolomite blocks for lining in electric arc furnaces (EAF) in 1952. The company, one of the few globally active dolomite producers, owns its own operation and plant in the city of Marone, near Lake Iseo, for the production of refractories materials and end products such as bricks and monolithics. Having been impacted by the financial crisis, Dolomite Franchi produced 96,800 tonnes in 2009, including 59,500 tonnes bricks and 37,300 tonnes monolithics, down from 121,000 tonnes in 2008, with respectively 75,000 tonnes bricks and 46,000 tonnes monolithics. Total sales revenue of the company was Û34.5m. ($46.6m.) down from Û42.2m. ($57m.) in 2008.

The raw material is mined in Galarusso, above Marone, since the old mining operation, located directly in Marone, closed down in 1980.

At full capacity, the dolomite factory operates in 20 shifts per week, 24 hours a day. The refractories are mixed by three fully-automated mixers, pressed by three hydraulic presses into various shapes and formats, and then finished in two tempering kilns.

Dolomite Franchi supplies its products worldwide. About 40% (Û14.1m.) of the production is sold in Italy directly, where the market share for dolomite is more than 70% and for dolomite mixes is nearly 90%. About 30% (Û10.6m.) is sold in other parts of Europe, while Asia (€4.5m.) and the Americas (€4.9m.) account for 27% of Dolomite Franchi sales. A very minor portion (Û0.4m.) is sold to Africa, mainly to Tunisia and Morocco.

Refractory properties

Dolomite, a niche product with an excellent cost-benefit ratio, is a unique product that has some good properties for chemical and mechanical resistance in extreme applications, namely refractories. It also shows a convenient elasticity modulus showing to be an ideal and environmentaly friendly substitute for magnesia-chrome products in cement.

Dolomite has a fantastic ability to attract and hold a clinker coating which protects the lining in a burning zone environment. This also helps to reduce the kiln shell temperature which reduces energy loss and input, saving costs.

The material also has a very good ability to resist alkali attack. Although it can suffer adversely from the attack of sulphur and sulphates, it is possible to modify the product bonding system to combat this attack mechanism. In addition, the increasing use of secondary or alternative fuels does not cause a problem for dolomite burning zone refractories.

However, one of the main concerns is that dolomite is hydrophobic. If not used properly, the mineral can hydrate and will decay if not protected from its reaction with moisture in the atmosphere.

Thanks to its properties and its lower cost compared to usual refractories minerals such as magnesia and bauxite in the present economic climate, research and development divisions have recently been focusing on developing new dolomite-based products for refractories applications.

Mauricio Pinho, from Magnesita Refratorios revealed to IM that the Brazilian dolomite producer and refractories manufacturer has worked to develop some new dolomite products with enhanced properties as increased thermo-cycling resistance for the cement kilns and corrosion resistance, specially for steel applications.

A boom in China?

The search for cheaper raw material or alternative to most strategic refractories minerals such as bauxite or magnesia has become a primary quest in the present climate. As a consequence, the popularity of dolomite for refractories has significantly increased during the last few years.

In many countries in the world regardless of the status of their industrialisation dolomite refractories used in the steel industry has the most potential. Being a refractory material for many applications in a mild steel operation from electric arc to steel ladles it has become the key refractory mineral for its application in the stainless steel sector due to its best price/performance ratio.

“We definitely see more potential for dolomite in our end-markets, not only because of a certain undersaturation, but also because of an increased technical acceptance in sectors, which so far were more dealing with magnesia-based products. An example might be the development of dolomite in high alloyed steel production with sophisticated production routes,” Alessandro Romano explained to IM.

Although the mineral does not have all the refractory properties of magnesite, it is of interest for the industry as a cheaper source of magnesia as dolomite prices are up to 40% lower (see panel).

Romano believes that dolomite could become an alternative in the refractories industry to strategic minerals such as bauxite; particularly in steel ladles, which are still lined with high-alumina bricks but not so much in special ceramics.

An interesting development is the adoption of doloma refractories to application areas, where dolomite has not been used so far.

However, overcoming the rivalry between moisture and dolomite would be a great progress in the field of electric arc furnaces (EAF) with water cooled panels.

The steel industry seems to offer significant opportunities in the future as plants all over the world are continuously checking possibilities to lower their production costs. In this context a possible application of dolomite products must be discussed as well. Depending on the supply situation of other refractories made from alumina or magnesia, new markets could emerge quite quickly such as China.

“Sooner or later the Chinese steel industry will detect dolomite as a refractory material for ordinary steel ladles and then create a boom for dolomite in China,” Romano said.

The impact on refractories would be positive. High grade magnesia raw materials, whose availability is becoming less, could be further used exclusively for sophisticated applications in the consumer industries, whereas the commodity part can be taken over by dolomite.

Challenges

Freight costs, which have recently significantly increased, remain a concern particularly in east and south Europe. However, they can be much cheaper to East Asia in countries such as Malaysia, Taiwan or Thailand. “It is sometimes just a few dollars more than if you go to the CIS [Commonwealth of Independent States] countries,” a source from the industry explained to IM.

According to Romano, one of the biggest challenges is to bring back dolomite to its reputation “as the best refractory material for a clean steel production”.

Due to the high affinity of dolomite to alumina and silica oxides, these main oxidic inclusions form phases with the lime (CaO) component of the dolomite and thus get captured in the brick or at its surface. “The risk of getting oxidic inclusions in the steel is less with dolomite than with other refractory materials. Therefore dolomite refractories contribute to a clean steel production,” he explained.

Outlook

After having been significantly affected by the financial downturn, the dolomite industry seems to now be back on track, following the trends of the steel industry. On the short term, 2010 has shown some improvement and next year should be a good year for dolomite.

“As we can see from incoming orders, the situation is further improving and I expect that already in 2011 we will see a very good year for dolomite,” Romano confirmed. However, the industry is not yet ready to pop champagne as it seems still premature to say if dolomite is really getting back to normal levels yet.

On the long-term the little push could result from the present raw material supply situation which could help dolomite emerge from the shadows.

Although it has remained until now a humble mineral compared to the usual star refractory minerals, dolomite could see its potential growing in the future as a cheaper alternative to magnesia, mainly supplied by China, which is trying to preserve resources and to feed its growing domestic demand.

“Despite of the decreasing specific refractory consumption in the steel industry, dolomite is expected to grow further because of an increasing substitution of other refractory materials by dolomite in steel ladles,” Romano forecast.

Pinho from Magnesita confirmed that the stainless steel market has shown some pick up and that dolomite consumption has increased. “We expect that the market will continue with this tendency, especially in Europe and Scandinavia as we see some consistent recovery in the production,” he said to IM. Magnesita has therefore planned to increase its present dolomite production of 500,000 tpa by 5-10% within the next few years (IM 22 November 2010: Magnesita to increase dolomite output by 5-10% within 3 years)

Reduced prices compared to minerals such as magnesia are obviously one of the key drivers to develop new dolomite-based products.

A very interesting development is the adoption of doloma refractories to application areas, where dolomite had never been used. “I would not see a big potential in tundishes but could imagine a remarkable share in production facilities of primary metallurgy,” Romano underlined.

Dolomite at a glance

• World production (2008): 103m. tonnes for dimension stone, including limestone, dolomite and related materials.
• US production (2009): 1.83m. tonnes (dimension stone)
• Value: $377m. in 2009 up from $324m. in 2008 (dimension stone)

Properties

• Sedimentary carbonate rock, also known as dolostone, consisting mainly of the mineral dolomite
• Formula: Calcium magnesium carbonate (CaMg(CO₃)₂); differs from calcite (CaCO₃) in the addition of magnesium ions to make the formula CaMg(CO₃)₂
• Found all over the world; quite common in sedimentary rock sequences; can be found in massive beds several hundred feet thick
• Deposits are usually associated with limestone
• Limestone partially replaced by dolomite is referred to as dolomitic limestone or as magnesian limestone
• Good chemical and mechanical resistance for extreme applications (refractories)
• Good elasticity

Uses

• Construction as a replacement for limestone
• Refractories as source of MgO
• Flux for the smelting of iron and steel where calcite limestone is uncommon or too costly
• Float glass production
• Horticulture: dolomite and dolomitic limestone are added to soils and soilless potting mixes to lower their acidity and as a magnesium source

Prices: a 40% cheaper alternative to magnesia?

According to industry sources, dolomite prices for finished product used in refractories range at an average of €350/tonne ($475/tonne) in Europe which is still 30-40% lower than price levels for magnesia carbon finished products such as bricks. It is around $550-650/tonne according to another world leading dolomite producer, depending on size, quantities and properties.

At present, dolomite is far less in the focus of the consumers than magnesia products. It is not considered a strategic mineral like bauxite and to a certain extent also magnesite. Therefore demand driven price fluctuations did not occur in the dolomite sector. The price development for dolomite was rather determined by comprehensible cost drivers like manpower, energy, binders and others. “Compared with the complexity of dolomite production, the dolomite prices are generally too low. And also ours,” Alessandro Romano from RHI ’s Dolomite Franchi told IM.

However, refractories manufacturers show an increased interest in dolomite as it is more and more seen as a cheaper alternative in terms of costs compared to usual refractories minerals such as magnesia.

As far as alumina based products are concerned, these are not any longer competing against dolomite in its typical application area in steel ladles. “In many cases, especially in the western countries, these products have already been substituted by dolomite,” Romano explained.

IM visited Dolomite Franchi which strip mines 0.5m. tpa in Galarusso, above Marone (by means of blasting) over the entire year. The deposit has a mine life of 35 years.

The crude dolomite is then transported in special lorries to the crushing and sifting plant before being conveyed by cable cars at 500 metres high to the production plant.

The crude material is then processed in six sintering furnaces into a refractory material which is processed into bricks or used for the production of mixes. As dolomite is hydrophobic, final products are then packaged with nine layers of hermetic aluminium and plastic sheets in order to resist humidity and avoid damage during transportation.

“Sooner or later the Chinese steel industry will detect dolomite as refractory material”

Alessandro Romano, head of Franchi Dolomite’s plant, talked to IM about the potential of dolomite for refractories

How is the market performing for dolomite?

Alessandro Romano: As far as demand is concerned, it shows a parallel curve to standard magnesia-based refractories. Since the major part of dolomite goes into the steel industry, the ups and downs of the steel sector are reflected in the development of dolomite as well.

What factors have most impacted the industry lately?

AR: It was for sure the economic crisis in 2008 and 2009, which led to a necessary downsizing of the installed capacities. Meanwhile, some of the strict measures could be released again. However, the industry is not yet back to business as usual.

What has changed in the industry?

AR: Similarly to many other branches, the dolomite industry has strongly concentrated on environmental issues. Whether it was new ecologic binders for shaped dolomite refractories or modernised plant equipment in order to minimise gas, dust and noise emissions, all these measures made dolomite refractories a very advanced, state-of-the-art product for the steel industry.

Where do you see emerging markets for dolomite?

AR: I think that steel plants all over the world are continuously checking possibilities to lower their production costs. In this context, a possible application of dolomite products must be discussed as well. Depending on the supply situation of other refractories made from alumina minerals or magnesia, new markets could emerge quite quickly.

Sooner or later, the Chinese steel industry will detect dolomite as refractory material for ordinary steel ladles and then create a boom for dolomite in China. 

What are the new R&D trends for dolomite?

AR: A very interesting development is the adoption of doloma refractories to application areas, where dolomite has not been used so far. I would not see a big potential in tundishes, but could imagine a remarkable share in production facilities of primary metallurgy.

Particularily I think about a revitalisation of its use in the big integrated BOF [basic oxygen furnaces] steel shops. But also overcoming the rivalry between moisture and dolomite would be a great progress in the field of electric arc furnaces (EAF) with water cooled panels.

What is your forecast?

AR: I expect the dolomite industry to grow further despite of the decreasing specific refractory consumption in the steel industry, because of an increasing substitution of other refractory materials by dolomite in steel ladles. 

As we can see from incoming orders, the situation is further improving and I expect that already in 2011 we will see a very good year for dolomite. Whether it will be already a year back to normal or just a single flash will become apparent in the future.