Definition
Calcium carbonate (CaCO3) is a mineral calcium compound, supplied to industry as a white meal or powder of varying fraction, used above all as a filler for plastics, paper, paints and rubber. It occurs in two basic commercial varieties: GCC — ground from natural rocks, and PCC — precipitated chemically, with a purer composition and a finer, controlled grain.
It is one of the most widespread and cheapest mineral raw materials of industry. From the perspective of a bulk-materials terminal, calcium carbonate is a cargo of a dual nature: chemically completely safe (inert, non-toxic, with no ADR classification), yet logistically demanding — because in the form of a fine meal it generates dust and cakes like any very fine mineral powder.
GCC and PCC — two types of calcium carbonate
Under the single name “calcium carbonate” hide two different products, differing not in chemical composition (both are CaCO3) but in the method of manufacture, and consequently in purity, fraction and price.
| Feature | GCC (natural ground) | PCC (precipitated) |
|---|---|---|
| Origin | grinding of limestone, marble, chalk | chemical precipitation from solution |
| Purity | depends on the deposit, with admixtures | higher, controlled |
| Fraction | broad range, down to micronised | fine and very fine, uniform |
| Grain morphology | irregular (a result of grinding) | defined (calcite, aragonite) |
| Cost | lower | higher |
| Main application | mass fillers, construction | high-quality paper, paints, technical plastics |
GCC (Ground Calcium Carbonate) is produced by grinding natural rocks — limestone, marble or chalk — to the desired fraction. It is cheaper and makes up the majority of the filler market. Its properties depend on the quality of the deposit: whiteness, chemical purity and the presence of admixtures (e.g. silica, metal oxides) derive from the raw material.
PCC (Precipitated Calcium Carbonate) is obtained by a chemical route — by precipitating the carbonate from solution, usually by carbonating lime milk with carbon dioxide. This gives a product of higher purity, a finer and more uniform grain and a controlled crystal morphology. PCC is more expensive and goes where repeatability matters: to high-quality paper, paints, technical plastics and certain food or pharmaceutical applications.
For a logistician the difference between GCC and PCC comes down mainly to fraction and flowability: very fine PCC and micronised GCC generate the most dust and are the hardest to discharge, while coarser GCC grades flow more freely. It is the fraction, not the type, that determines how the material will behave during transloading.
Parameters and form
Calcium carbonate is supplied as a dry powder of a fraction matched to the application — from coarser construction meals to micronised grades for plastics, where the particle size descends to single micrometres. The finer the fraction, the better the filler “disappears” into the polymer and the higher the price, but also the stronger the dusting and the tendency to aerate and cake.
The key parameters from a transport and transloading point of view:
- Bulk density — typically approx. 0.8-1.3 t/m3, depending on the fraction and the manner of filling. Fine, aerated meals are lighter (closer to the lower limit), coarser and compacted ones are heavier. Loose density (freshly poured, aerated material) and tapped density (after vibration and settling) are distinguished. This difference can be significant and directly affects how much material will fit in a silo trailer and how it will behave during discharge.
- Dusting — the fine fraction generates strong dust; during transfer it rises into the air and settles on the surroundings. This is the main occupational safety and cleanliness challenge in transloading.
- Hygroscopicity — low, but moisture cakes the material; that is why storage and transport must be dry.
- Inertness — chemically inert, non-toxic, non-flammable; no ADR classification.
- Abrasiveness — the mineral meal abrades installation components (valves, hoses, fluidising bottoms) — this is a factor in equipment selection and operation.
From a bulk-transport perspective it is important that fine CaCO3 readily aerates (fluidises) and then behaves almost like a liquid — which eases pressure discharge but requires sealed installations, because aerated meal “seeks out” every leak and generates dust there.
ADR and safety
Calcium carbonate is a non-ADR material — it is not a dangerous good and is not subject to the regulations on the transport of dangerous goods. It is chemically inert, non-toxic and non-flammable. This places it in the same group as most of the cargoes handled at our terminal, where the rule is that we accept “anything that flows well and is not ADR”.
The absence of a hazard classification does not, however, mean the absence of requirements. Mineral dust is subject to occupational safety regulations — maximum permissible concentrations for dusts in the workplace apply regardless of the non-toxicity of the compound itself. That is why transloading the meal is carried out so as to limit dust emission to the surroundings: with sealed chutes, by limiting the free fall of the material and, if necessary, with dust extraction. A chemically safe cargo still requires proper work organisation.
Calcium carbonate as a filler for plastics
The most important application of CaCO3 from the perspective of granulate logistics is its role as a filler for plastics. It is added to polyolefins and PVC in order to:
- lower the cost of the product — the mineral filler is cheaper than the polymer it replaces;
- increase stiffness and dimensional stability;
- improve whiteness, opacity and printability of films and products;
- modify mechanical and processing properties.
Most often, calcium carbonate does not reach the processor as a pure powder but as a masterbatch — a filler concentrate dispersed in a polymer carrier (usually PE or PP) and supplied in the convenient form of a granulate. The masterbatch producer buys CaCO3 meal in bulk, mixes it with polymer and extrudes the finished granulate, which the processor doses into its blend. In this chain, CaCO3 meets polyethylene and polypropylene as carriers, and especially often PVC, where calcium carbonate is one of the basic additives — in pipes, window profiles and flooring its share can be very high.
Here an interesting connection emerges between the streams handled by the terminal: the same logistics that delivers the polymer granulate also delivers the mineral filler that will end up inside that granulate. The cleanliness of both streams matters — contamination of the filler with a foreign grain or metal will carry over into the plastic product, which is why here too the control on cleaning screens, separating clumps and foreign bodies, is useful.
Other applications
Beyond plastics, calcium carbonate is one of the most versatile industrial raw materials:
- Paper — as a filler and coating (especially PCC) it improves whiteness, opacity and printability; the paper industry is one of the largest customers.
- Paints and coatings — a filler that lowers cost and regulates rheological and covering properties.
- Rubber and adhesives — a reinforcing and bulking filler.
- Construction — aggregates, mortars, mixes, where coarser fractions are used.
- Agriculture — soil liming (though here more often in coarser grades).
- Food and pharmaceutical — pure CaCO3 as an additive (e.g. a source of calcium, an acidity regulator) — here the purity requirements are highest and the material usually comes from dedicated, certified lines.
Each of these industries expects a different fraction and a different purity, which means — as with granulates — that “calcium carbonate” is not a single product but a whole family of grades with strictly defined parameters. For a transloading terminal the consequence is the same as with plastics: batch traceability and not mixing grades are fundamental, because food and construction meal look almost identical yet go to entirely different places.
Transloading and logistics
From the perspective of the terminal in Chorula, calcium carbonate is a typical dusty mineral powder — like cement it requires dust emission control, though unlike cement it is not chemically reactive. There are three challenges:
- Dusting. The fine meal rises at every transfer. Transloading is therefore carried out with a limited free fall, with sealed chutes where possible, and with dust extraction at critical points. The goal is for the material to pass from the packaging into the tank without a “cloud”.
- Caking and moisture. Meal exposed to moisture cakes and loses flowability, which hinders discharge and spoils the batch. That is why storage is carried out in dry conditions, and during pressure discharge dry air is ensured.
- Flowability and aeration. Fine fractions fluidise superbly — this eases the discharge of the silo trailer but requires a sealed installation, so that the aerated powder does not escape through leaks.
We most often receive the material in big-bags or octabins from imports and production, maintain a buffer store and transfer it to silo trailers at the rhythm of the customer’s orders. Fine, well-flowing grades travel in bulk by silo trailer with pressure discharge; coarser fractions and smaller batches remain in big-bags. We describe the transfer service in more detail on the big-bag to silo trailer transloading page, and you will find the full offer of bulk-material transport in the PHS Magnum portal.
It is worth emphasising the difference from polymer granulates: there the main enemy is contamination and mechanical damage to the grain (angel hair), so a gentle transloading without pneumatics is used. With limestone meal the priority, by contrast, is mastering dust and moisture and selecting equipment resistant to abrasion. This is a good example of the fact that there is no single, universal transloading method — the working method is matched to the physics of the specific material, and the terminal’s experience lies precisely in correctly recognising how a given cargo will behave.
Fraction as the key — why grain size decides everything
In the calcium carbonate trade it is not the type (GCC or PCC) but the fraction that is the parameter most strongly affecting the behaviour of the material in the supply chain. The same meal, ground coarser or finer, is practically two different cargoes.
Coarser fractions — construction, aggregate — flow freely, generate little dust, have a higher and more predictable bulk density, and their discharge causes no trouble. Fine and micronised fractions, descending to single micrometres, behave the opposite way: they generate strong dust, aerate and fluidise easily, and once settled they cake. The finer the meal, the more valuable the product (for plastics and paper), but also the harder to handle. That is why, when accepting a load, the question about the fraction is as important as the question about the material itself — it determines whether the batch will travel in bulk by silo trailer or remain in packaging, and what dust-control measures must be provided.
This also has consequences for equipment selection. Fine, abrasive meal abrades the components of the discharge installation — valves, fluidising bottoms, hoses — faster than equipment-friendly polymer granulate. This is an operational factor that the terminal must take into account in maintaining its silo trailers and fittings, in order to preserve the tightness of the installation — and tightness with a dusty material is a condition of clean work.
Imports and the supply chain
Calcium carbonate is sometimes a local raw material — mined and ground near the processor’s plant — but a large part of the specialist grades (especially high-purity GCC from particular deposits and PCC) circulates in international trade, including in imports from Asia. The chain is then similar to the granulate chain: production plant → port → inland terminal → the customer’s silo or warehouse. On the final stretch, leading to the processor’s plant in Central and Western Europe, what counts is an efficient, clean delivery and flexibility in the choice between bulk delivery and packaging.
This is precisely where a transloading terminal plays the role of an intermediate link. The meal usually arrives in packaging — big-bags or octabins — because this is a convenient form for a container and a warehouse. A customer with a silo installation, however, prefers bulk delivery, without having to cut open hundreds of bags. Transferring from the packaging into a silo trailer, carried out with dust control, combines these two worlds and allows the material to be delivered in the form a particular plant expects. Among the terminal’s regular customers in bulk-material logistics are, among others, LG Chem, Borealis, Synthos and Orlen — buyers and suppliers from the plastics industry, for whom mineral fillers are a natural complement to the granulate stream.
Related topics
Calcium carbonate is best understood in two contexts: as a dusty mineral powder — logistically comparable to cement — and as a filler for plastics, where it meets PVC, polyethylene and polypropylene. It is transported in big-bags and in bulk by silo trailer, and contamination control is provided by cleaning screens. On the services side, see storage and packing of bulk materials.
Sources
- Safety data sheets and technical specifications from calcium carbonate manufacturers (GCC/PCC).
- Occupational safety guidelines concerning mineral dusts in the workplace (exposure limits).
- Industry materials concerning mineral fillers for plastics and paper.
- Operational practice of the SMIALA terminal, Chorula — Aleksy Pasternak.
