End User Focus: Under mineral lock & key

By Alex Feytis
Published: Wednesday, 26 October 2011

As an emerging niche market, carbon capture and storage could bring demand potential for magnesium and calcium oxide-rich industrial minerals

One niche market is gaining more and more attention from the industrial minerals industry: that of carbon dioxide (CO2) sequestration or storage, which aims to reduce greenhouse gas (GHG) emissions into the atmosphere.

Carbon capture and storage (CCS) is the process of capturing, transporting and storing anthropogenic CO2. The CO2 is sequestered from large industrial sources such as coal, oil and gas facilities before it is released into the atmosphere. It is then transported through pipelines - similar to those used to transport natural gas and oil - and permanently stored in reservoirs or in other deep geological formations. The selected storage sites are at depths of 1-5km below the surface and exhibit the geologic conditions necessary to ensure that these reservoirs can retain the CO2 for long periods of time. Small volumes of CO2 can also be transported as a liquid in ships, tanker trucks or rail tankers.

Carbon capture and storage is of increasing interest to the raw materials industry as industrial minerals rich in magnesium oxide (MgO) and calcium oxide (CaO) - including brucite, olivine and wollastonite (see table) - are naturally capable of sequestering CO2 before transforming the gas into a geologically and thermodynamically stable form, ie. carbonates, that can be stored.

Olivine for instance, once milled to expose additional surface area, breaks down in a few years to form carbonates through the carbonation process. This process of chemical weathering can be enhanced to increase CO2 sequestration and suggests that olivine and other similar minerals, once crushed and spread on fields to expose them to high levels of anthropogenic CO2, could be used to pick up carbon dioxide from the atmosphere in addition to supply essential magnesium, calcium, silica and iron to the growing plants.

Much of the research into mineral carbon sequestration has looked at methods of speeding up the carbonation process, which is inherently slow under natural conditions, to create an industrially viable system owing to the global reserves of suitable minerals.

The minerals can be processed to particle sizes of less than 100 microns to expose a high surface area for faster reaction that improves carbonation rates. The resulting carbonated products could provide a useful source of additional revenue, as they can be used in construction applications or mine reclamation.


Minerals proposed for carbon sequestration



Source: George Hawley, consultant, George C. Hawley Associates


Magnesium oxide

Magnesium oxide is said to be more effective in reacting with CO2 than calcium oxide as, in theory, one tonne of brucite (containing MgO) can capture 0.75 tonnes of CO2 while CaO-bearing wollastonite will sequester a lower amount of 0.38 tonnes.

Sources of MgO, which is used in basic refractories, could therefore be seen as good potential materials for CCS. But at present, the application does not seem to have yet attracted the attention of producers.

“It is something that we have been aware of however it is not something that we are following with any great interest, just watching,” a world-leading magnesia producer told IM.

“Basically we do not think the science is developed well enough for this application to figure in our current strategic marketing plan,” the producer added.

Brucite, a natural magnesium hydroxide mineral which has a content of 69.1% MgO, could be seen as a good choice. Carbonate-hosted brucite deposits of economic significance are found in Canada, Norway, Russia, and the USA. Undeveloped or exhausted brucite deposits occur in Arizona, USA; British Columbia, Canada; China, Ireland, North Korea and the UK.

The white colour of brucite is an advantage as the magnesium carbonate produced from the reaction with carbon dioxide tends to be white, and thus could be suitable for use as a white extender pigment to compete with calcium carbonate.

Newly-formed International Brucite Corp. (IBC) became North America’s leading producer in November 2010 following the bankruptcy of the deposit’s former developer, Applied Chemical Magnesias Corp. (ACM), in 2009.

Olivine

Olivine, with 45-51% MgO content, technically has a good potential for CCS as it breaks down in a few years to form carbonates when crushed and exposed to CO2.

World capacity in 2008 totalled about 9m. tpa but actual output could be as low as 6.5m. tonnes at present. The main producer is Norway, followed by Japan and Spain.

Globally, the largest olivine producer is Norway-based Sibelco Nordic (formerly North Cape Minerals A/S) whose three olivine mines in Norway - Aheim, Bryggja and Raubergvik - have a combined capacity of 2.4m. tpa.

However, olivine price remains a source of concern. “A lot of people are asking about the use of olivine in CO2 sequestration. But it is not moving yet,” a leading world producer of olivine commented to IM.

According to the Faculty of Geosciences at Utrecht University in the Netherlands, about 140g olivine is needed to sequester 176g CO2. In a report, the university recommend to spread large quantities of milled olivine over the Earth’s surface.

“To remove 1bn tonne of CO2, 0.5% of the land surface (just over 5% of Siberia) should be covered by a 0.4mm thick layer of olivine grains, preferably by mixing them with fertilisers before spreading,” the university suggested.

A source from the industry commented to IM that the use of olivine in a country hosting the mineral could be possible as there would not be much freight cost involved. “Otherwise it would not be worth it if the mineral has to be transported to be used for CO2 sequestration,” the source declared, adding that freight prices to transport minerals have significantly grown.

As reported by IM, olivine prices have shown signs of increasing. Prices currently range at $60-90/tonne but some prices were reported at up to $100-200/tonne depending on the grade, meaning that it is not economically viable to use the mineral.

“At some point CO2 sequestration could have a great potential, perhaps within the next 10 years. It is just a question of training the industry,” the source told IM.

US carbon dioxide emissions growth*



Source: Short-term energy outlook, September 2011, EIA
* Change from previous year


Dunite

Dunite, which is about 50% olivine and 50% serpentinite, is increasingly used in refractory applications but could also be used for CCS. The mineral is produced by Pasek SA in Galicia, Spain.

“Dunite is a natural candidate due its capability to react with CO2, fixing it as bicarbonate as first step of dissolution of CO2,” Roberto Caballero, manager of Pasek’s new division Pasek Technical Center (PTC), told IM, adding that “CCS is a new opportunity for some industrial minerals such as dunite”. As for all mineral candidates for CCS, particle size and reaction parameters such as pressure and temperature have a strong influence.

Today, there is no dunite produced for CCS but Pasek is “pushing dunite’s CCS potential from R&D and sales departments”. Caballero revealed that Pasek is in contact with several companies interested in minerals for CCS.

“We hope to start supplying as soon as possible,” Caballero said.

Wollastonite

Wollastonite, thanks to its 48.3% CaO content, could be used in CCS as it is high in purity. Although it is theoretically only about half as efficient as brucite in sequestering CO2, wollastonite is much more widely available.

According to the US Geological Survey, estimated wollastonite crude ore production increased in 2010 and was in the range of 550-575,000 tonnes in 2010 compared with 520-540,000 tonnes in 2009. The main producers are China (300,000 tonnes in 2010), India (145,000 tonnes), the USA (65,000 tonnes in 2009), Mexico (40,000 tonnes), Finland (16,000 tonnes in 2009) and Spain (7,000 tonnes in 2009).

In addition, the by-products from sequestration should be marketable and of reasonably high value as wollastonite reacts with sulphuric, carbonic and hydrochloric acids to produce calcium sulphate (gypsum), calcium carbonate (calcite) and calcium chloride, respectively. The first two are insoluble; calcium chloride is soluble and will pass out in the liquid wastes.

Wollastonite can also remediate flue gases containing sulphur, chlorine and carbon emissions.

NYCO Minerals Inc., a USA-based leading producer of chemically modified wollastonite, believes that wollastonite is being given “serious consideration” as a material to be potentially used in the CCS process.

“[It] has been reported to be one of the most reactive minerals in this process and the availability of both calcium and silica from wollastonite are of particular interest in the CCS process,” NYCO’s technical marketing manager Sal LaRosa told IM.

However, LaRosa pointed out that the market potential for wollastonite is still in the development stage and a commercial opportunity is not yet understood.

“If the conversion process proves to be commercially viable, the potential for wollastonite in this market could be significant,” he said, underlining that the “development of the CCS process will depend on cost, economics and the ability to create a material out of the CCS process that has value”.

As a consequence, NYCO which “is aware of the potential use of wollastonite in CCS”, plans to continue working with companies that have an interest to evaluate wollastonite for this application.

Limestone in FGD

Many industrial applications, such as coal-fired power stations, require the combustion of hydrocarbons and thus emit sulphur dioxide (SO2) into the atmosphere. Other processes, such as the incineration of waste, also generate SO2 and other acidic gases such as sulphuric, sulphurous and hydrochloric acids which increase the acidity of the atmosphere and promote acid rain.

Limestone remains an important mineral in the flue gas desulphurisation (FGD) market, as it is used with lime to sequester SO2, which in many cases produces gypsum as a by-product. About 600kg limestone is needed to capture 1 tonne SO2, and generates almost two tonnes of gypsum as a by-product.

Flue Gas Treatment (FGT) represents the second largest market of the turnover of Carmeuse Group, the world-leading limestone producer headquartered in Belgium.

“This market is an important market, aligned with our target to be a reference supplier with full technical support for our customers,” Carmeuse CEO Rodolphe Collinet told IM.

As Carmeuse explained, limestone “is the preferred sorbent and will remain in the future” owing to the volume needed, the proven calcium-based technology and the limestone availability.

“FGD market needs proven, efficient and reliable solutions to comply with legislation without risk. The technology is looking more like an evolution than a revolution,” Collinet said.

North America and Europe are important markets for FGD. Although legislation is slightly different, the goal and the customer’s needs are comparable, Collinet believes. Volumes and logistics are different because of local realities such as limestone availability, the coal share in electricity production and the logistics network.

Collinet believes that global FGD market should be growing in the coming years in some regions such as Eastern Europe or mid-west USA and in countries with a strong growth potential.

“This is highly dependent on the coal share use in electricity. This topic is highly strategic at state level in terms of mix, cost and safety of electricity supply,” Collinet commented.

In Jamaica, limestone producer Lydford Mining Co. Ltd told IM that the company, which focuses on whiting grade, high bright limestone for paints, plastics, fillers and high purity limestone used in food and pharmaceutical grades of limestone is entering the market for FGD in coal-fired power stations.

“We have the criteria in place: quality limestone, port, shipping, and an expanding market for FGD,” explained CEO Leo Cousins, adding: “It is worth it if you gear for quantity and put the equipment for volume output in place - 500,000 tpa to 1m. tpa.”

In 2010, Lydford exported about 80,000 tonnes into the USA in partnership with TBS shipping from New York, which operates a bulk carrier fleet of ships. The company loads in 40,000-tonne carriers from the port of Ocho Rios in Jamaica, discharging into barges at the port of New Orleans.

As Cousins highlighted, limestone is a very low-priced commodity with the current market price between $8-14/tonne FOB. “In this usage, the price paid is based especially on the purity and reactivity of the limestone for trapping carbon dioxide. Sizing, volumes, moisture content, port fees and geographical location to user, are other factors considered. The abrasiveness of the limestone is another factor in the grinding costs to be incurred,” Cousins declared.

FGD is dependent on environmental laws in each country so the growth is dependent on political considerations, the main challenge being geography - ie. the distance from user to producer - and logistics.

However, Cousins believes that “food grade, lime, cement, and construction aggregate will always be more profitable than FGD economically speaking”.

CCS forecast

CCS is expected to play a significant role in decreasing industrial CO2 emissions around the world. The US Energy Information Administration (EIA) estimates that CO2 emissions from combusting fossil fuels increased by 3.9% in 2010. Forecast fossil-fuel CO2 emissions are estimated to fall by 0.7% in 2011, as emission increases from higher natural gas consumption are offset by declines in coal and petroleum consumption. Increases in hydroelectric generation and other renewable energy sources in 2011 will also help to mitigate emissions growth.

Fossil-fuel CO2 emissions in 2012 are forecast to remain stable as expected declines in coal emissions are nearly equalled by the increases in emissions from petroleum and natural gas.

According to the International Energy Agency (IEA), global demand for energy will continue to increase. This will be driven by emerging economies and continued global prosperity. Forecasts suggest a 50% increase in global energy demand by 2030, meaning that we will need all sources of energy to meet this demand. This includes a continued role for fossil fuels including coal, oil and gas, along with emerging energy sources such as wind, solar, and hydroelectric.

Meanwhile, CO2 management actions will be needed by both energy producers and energy consumers as environmental stresses are growing, particularly around CO2 and global warming.

All technologies along the CCS chain have been in operation in various industries for decades, although in relatively small scale. IEA explained that “these technologies have only been put together in industrial scale in a small number of installations. No large-scale installations exist yet in electricity production.”

IEA analysis suggests that CCS will play a vital role in worldwide, lowest-cost efforts to limit global warming, contributing around one-fifth of required emissions reductions in 2050.

“For CCS to reach this potential, around 100 CCS projects would need to be implemented by 2020 and over 3,000 by 2050,” IEA pointed out.

Although the application does not seem to be a major concern for mineral industry players yet, the amount of industrial minerals used in CCS could increase accordingly in the future as a result of this emerging market. However, the process would take time and would depend on various factors such as mineral prices, freight, and the development of the technology.

“This capability was probably investigated in the past but, today, it appears to be necessary. In my opinion, the market for mineral sequestration of CO2 will take a long time and process will be slow,” Caballero from Pasek commented to IM.

Caballero believes that “reaction technology would be guided to a universal solution at room conditions”, for example a layer of mineral covering the whole Earth as mentioned by the university of the Netherlands. “On the other hand, really difficult reaction technology would be focused on high performance reactors to get instant sequestration,” he added.

CCS being directly related to the energy market, one important factor will be political as the increase of CCS will depend on environmental laws and regulations to be voted on in the future, in Europe as in the rest of the world.

“CCS is not a long-term solution but a transitional solution,” as one mineral producer explained.