Calcium Carbonate – modern day applications

Major industrial applications of GCC and PCC

Calcium carbonate powders, precipitated products and dolomite, are among the most important and versatile materials used by industry.

Modern calcium carbonate uses – paper, paint, rubber, plastics, household products, sealants, agriculture, bread, pharmaceuticals, glass

Both ground calcium carbonate (GCC) and precipitated calcium carbonate (PCC) are used in an increasingly wide range of applications. Commercial grades of calcium carbonate have been developed to meet the technical demands of a different requirements by optimising properties such as fineness, particle size distribution and colour.

Principal applications for ground calcium carbonate (GCC)

Adhesives and sealants
Animal and pet feeds
Carpet-backing
Construction (concrete, plasters, asphalt)
Environment (desulphurisation of flue gas)
Fertilisers and agricultural liming
Food and pharmaceuticals
Glass and ceramics
Household products
Paints and surface-coatings
Paper
Plastics and composites
Rubber and elastomers

Further information on major GCC applications

Principal applications of precipitated calcium carbonate (PCC)

Cosmetics and toiletries
Food and pharmaceuticals
Paints and inks
Paper
Plastics
Sealants and adhesives

Further information on major PCC applications

NB: Dolomite Uses

Uses for dolomite are largely similar to those for GCC. However, its magnesium content excludes it from another of applications e.g. foods, pharmaceuticals, etc. On the other hand, magnesium, like calcium, is an important biological element, which is of interest in agriculture and forestry. Dolomite and magnesium limestones are therefore used for agricultural liming and the rehabilitation of over-acidified lands and waters.

Calcium Carbonate – geology

A story spanning over 200 million years of the UK’s history

UK calcium carbonate geology is based on 3 principal resources: Carboniferous limestone, Cretaceous chalk and Dolomite (a mixed carbonate of calcium and magnesium).

With the exception of dolomite all have the same chemical formula but due to distinct differences in there formation, have different properties.

Sedimentation and rock formation

Original carbonate deposition

calcium carbonate deposition

Flat land surface. Shallow, warm sea. Minimal sediment washed in from land. Deposition of calcium carbonate in skeletons of marine organisms

Sedimentation is the rock forming process from which all limestones, including chalk and, ultimately, marble originate.

Sedimentary rocks generally form in two stages: initially loose materials are deposited in layers, and then they are consolidated to rock by pressure or cementation. The physical, chemical or biological alteration of sediments into sedimentary rock is called diagenesis.

Rocks of biological origins

Most significant limestone deposits are derived from organogenic sedimentation meaning the original material forming the basis of the rocks is of biological origin. This mainly concerns the inorganic remains of invertebrates which deposit on the seabed and become consolidated in the course of time. The size of the component elements range from whole and broken shells of molluscs to coccoliths (single-called marine algae) measuring a few thousandths of millimetre.

Calcium Carbonate – history

Uses of CaCO3 from prehistory to modern times

history of calcium carbonate uses from prehistory to the middle ageshistory of calcium carbonate uses from the middle ages to the industrial revolutionhistory of calcium carbonate uses from the industrial revolution to modern times

Calcium carbonate has been used from as early as 40,000 BC to present day. The history of calcium carbonate illustrates how we have been able to utilise the unique properties of this mineral in applications ranging from prehistoric cave paintings to modern paper and plastic manufacturing.

Calcium carbonate uses over the ages – from prehistoric cave paintings and glass to rubber products used in modern cars.

The Anglo-Saxons referred to chalk as “Hwiting-melu”, literally “whitening powder”. And this was exactly what chalk was used for over the millenia, be it as a white pigment in paints, primers and plasters.

The main preconditions for the widespread of chalk over other forms of calcium carbonate, were the ease with which it could be quarried and processed. The Anglo-Saxons quarried chalk all around Dover on the South Coast. They found the soft rock could easily be quarried with simple tools such as saws and axes. Moreover it was usually sufficient to merely crush and grind the chalk chunks to produce a powder in the required quality

Chalk is still referred to as “whiting” to this day but, along with other forms of ground calcium carbonate including limestone and marble, is now used in a wide range of products that touch people every day lives. Calcium carbonate is one of the most widely used raw materials in the world and new applications are constantly being developed so it is likely that its use will continue to grow well into the next millenia.

Calcium Carbonate – production

Processing and production of industrial fillers based on calcium carbonate

Viet Nam calcium carbonates are a nationally significant source of raw materials. Commercial calcium carbonate grades, in the form of powders, granules and slurries, are produced in 2 ways: through the extraction and processing of natural ores or synthetically through chemical precipitation.

chalk quarry, humberside

Ground calcium carbonate, commonly referred to as GCC, is primarily based on limestone and chalk in Viet Nam, though marble stone is imported and processed at a few locations.

Precipitated Calcium Carbonate (PCC) is produced through a recarbonisation process or as a by-product of some bulk chemical processes.

Dolomite fillers are also produced from indigenous stone, similar to GCC, but as Viet Nam has no viable source of high whiteness dolomite rock, again this material is also imported but processed locally by a few  companies.

GCC Production

Though there are extensive reserves of chalk, limestone and dolomite in Viet Nam, in reality only a few deposits are of sufficiently high quality to be able to provide raw materials for industrial and agricultural uses. Only if the purity, colour, thickness and homogeneity are acceptable is commercial extraction worthwhile.

SEM of ground calcium carbonate

SEM of ground calcium carbonate (GCC)

After quarrying, further treatment is required to process natural calcium carbonates (and dolomite, which is very similar) of the highest quality, known generically as Ground Calcium Carbonate (GCC).

The production process maintains the carbonate very close to its original state, ending up in a finely ground product delivered either in dry or slurry form (water based suspension).

bulk tanker delivery of fine limestone powder

Bulk tanker delivery of fine limestone powder

Generally, the processing includes washing, sorting of undesirable contaminants, grinding, size classification of particles and possibly drying. Depending on the circumstances and intended uses, the order and necessity of those different steps vary. At the outlet of the process, the material is delivered in bags or in bulk when dry, or as bulk tankers for slurries by road or rail.

GCC Production Process schematic: Extraction and processing of GCC

Surface treatment of GCC is another aspect of adding value to the basic material. Such coatings aim to match the surface tension of calcium carbonate fillers with that of the compounds (e.g. thermoplastics) in which they are incorporated.

PCC Production

Most commercial producers use the recarbonisation method of PCC production where limestone is converted into calcium oxide (lime) and carbon dioxide by calcination at high temperatures. After calcination the lime is slaked with water and the resulting milk of lime is purified and re-carbonised with the carbon dioxide obtained directly from the calcination process.

storage silos

Silos used for storing calcium carbonate prior to delivery by bulk tanker to the customer

This produces a water-based suspension of CaCO3. A cake comprising upto 60% solid matter (depending on particle diameter) is then obtained by filtration. This filter cake is then dried and subsequently disagglomerated in grinders.

Depending on the chemical composition of the milk of lime used and on the purifying stages during production, food and pharmaceutical grades as well as technical grades can be produced.

Coated grades of PCC are also produced by introducing fatty acids or other additives at the suspension stage prior to filtration.

SEM of scalenohedral precipiated calcium carbonate

SEM of scalenohedral precipiated calcium carbonate (PCC)

The fineness of the grain, as well as the morphology of the PCC crystals can be modified during the process by controlling temperature, concentration and time. There are three main crystal morphologies: Calcite, Aragonite, and Vaterite. Within each morphology, several crystal forms are possible. This opens up interesting possibilities of tailoring PCC products to specific use applications.

10 Things you might not know about CaCO3

A few interesting facts about calcium carbonate

1st unusual fact about calcium carbonate

Calcium carbonate is one of the most common minerals

Calcium carbonate makes up 4% of the earth’s crust. Over 20% of the World’s sedimentary rocks are composed of chalk or limestone.

2nd unusual fact about calcium carbonate

Calcium carbonate – plant or animal or both?

Limestone is an inorganic, sedimentary rock formed from the remains of microscopic animals or foraminifera. Chalk was also thought to be derived from foraminifera but in 1953 was shown to be largely composed of coccoliths, a lime-secreting algae. So both.

3rd unusual fact about calcium carbonate

The world’s oldest building is made of calcium carbonate

Khufu’s Pyramid, usually referred to as the “Great Pyramid”, is the world’s oldest structure and consists of 2.5 million limestone blocks, each one weighing an average of 2.5 tonnes.

4th unusual fact about calcium carbonate

Chalk whiting – a Saxon connection

Ground Chalk has been commonly known for centuries as Whiting. It is believed ‘whiting’ is derived from the Saxon word, ‘Hwíting-melu’, which literally means ‘whitening powder’.

5th unusual fact about calcium carbonate

Calcium is the fifth most abundant element in the body

Calcium is an important structural component of bones and teeth and also is necessary for the normal function of all muscles and nerves.

6th unusual fact about calcium carbonate

When pasta was made from chalk

Pasta, the Italian term for dough originally referred to how painters produced their pastel chalk. They kneaded chalk, pigment powder and an aqueous binder into uniform dough from which pencils were formed and finally dried.

7th unusual fact about calcium carbonate

Calcium carbonate exists only on Earth and possibly on Mars

In Shergotty, India a meteorite fell from the sky which is believed to have originated from Mars. The meteorite contained calcium carbonate, as well as traces of gypsum.

8th unusual fact about calcium carbonate

Blackboard chalk isn’t chalk

The base of pastel chalks is not calcium carbonate but calcium sulphate (CaSO4), which is derived from gypsum (CaSO4-2H2O). Pastels also contain clays and oils for binding and strong pigments.

9th unusual fact about calcium carbonate

Chalk and Cheese – a scam in the Middle Ages

14th century Welsh market traders used to try to pass chalk off as a hard cheese on unsuspecting customers, hence the popular term ‘like chalk & cheese’

10th unusual fact about calcium carbonate

The white cliffs of Dover are “rare”

Though white cliffs are fairly common in England the only other chalk cliffs in the world, are in Northern Ireland, France, Denmark and Germany. Chalk geology is rare in the World, confined to northwest Europe; thus it is of global importance.

Calcium Carbonate – an exceptional mineral

Calcium carbonate is composed of three elements which are of particular importance for all organic and inorganic material on our planet: carbon, oxygen and calcium. Calcium carbonate (CaCO3) is a white solid, is non-toxic and odourless.

Download presentation about Calcium Carbonate and the British Calcium Carbonates Federation.

stalagmite composed of calcium carbonate

The earths crust contains more then 4% calcium carbonate, making it one of nature’s most abundant raw materials. Calcium carbonate is found as rock in all parts of the world, is the main component of seashells and is usually the principal cause of hard water. As well being dissolved in rivers and oceans, the mineral can be found in molten form as “cold” carbonatite-lava, or as a solid in the form of stalactites, stalagmites or as the major constituent of whole mountain ranges.

10 things you might not know about calcium carbonate

chalk is largely made up of coccoliths, the remains of a lime-seceting algae

Calcium carbonate geology

Calcium carbonate is normally found as a white mineral (calcite) which occurs naturally in chalks, limestones and marbles. Some of these rocks were formed by inorganic processes, but many are of organic origin being composed of the remains of countless sea organisms. Most are limestones, a general term used for a rock possessing varying proportions of calcite and dolomite with small amounts of iron-bearing carbonates. Dolomite is a double carbonate of calcium and magnesium, with the formula CaMg(CO3)2. Limestones are usually clear or white. However, with impurities, they can take on a variety of colours, commonly white, tan or grey.

More about calcium carbonate geology

The most common crystal arrangement for naturally-occurring calcium carbonates is the hexagonal form of calcite. Less common is aragonite, which has a discrete or clustered needle, orthorhombic crystal structure. Aragonite is formed in a narrow range of physio-chemical conditions, typically in thermal springs although mollusc shells and pearls are made of aragonite.

chalk extraction, Humberside

Calcium carbonate production

Commercial calcium carbonate is produced in 2 ways: through the extraction and processing of natural ores or synthetically through chemical precipitation. Ground calcium carbonate is commonly referred to as GCC. Precipitated Calcium Carbonate (PCC) is produced through a recarbonisation process or as a by-product of some bulk chemical processes (e.g. the Solvay method or caustic soda production).

How calcium carbonate is turned into fillers and functional additives

A long history of uses from prehistory to the present day

Calcium carbonate has been used since prehistoric times to the present day. The history of calcium carbonate shows how we have been able to utilise the unique properties of this mineral to improve the quality of life through the ages.

Historical uses of calcium carbonate

Modern calcium carbonate uses - paper, paint, rubber, plastics, household products, sealants, agriculture, bread, pharmaceuticals, glass

Today, Calcium carbonate powders, precipitated products and dolomite, are among the most important and versatile materials used by industry. It is used as a filler and functional additive in an incredible variety of industrial applications ranging adhesives & sealants, building products, glass, paints & inks, paper, plastic & rubber to animal feeds, flue-gas desulphurisation, fertilizers, food, personal care, pharmaceuticals and water treatment.