In the industrial fields of chemical fillers, rubber and plastic, papermaking, coatings, etc., calcium carbonate is the most widely used inorganic powder raw material. The mainstream on the market is divided into two categories: heavy calcium carbonate (GCC) and light calcium carbonate (PCC). Both are based on calcium carbonate as the raw material, and some ultrafine specification products can even replace each other in about 90% of scenarios. However, there are significant differences in production processes, physical and chemical indicators, and usage effects, making it easy for many practitioners to confuse when selecting. This article systematically summarizes the core differences between two types of calcium carbonate from 12 dimensions, including production process, physical indicators, powder characteristics, economic and environmental protection, and practical applications, providing clear references for raw material selection.
Ⅰ. Different production and preparation processes
1. Heavy calcium carbonate (GCC) takes calcite, marble, limestone, chalk, White Marble and other natural carbonate ores as raw materials, without chemical reaction, and is only made into powder through pure physical mechanical processing such as crushing, grinding, grading, etc. The process is simple, and the ore itself is directly crushed and refined.
2. Light calcium carbonate (PCC) is a chemically synthesized powder based on limestone. The entire process includes multiple chemical processing steps, including high-temperature calcination, water digestion, carbonization reaction, dehydration, drying, and fine grading, accompanied by chemical conversion reactions throughout the process.
Ⅱ. Significant difference in bulk density
The bulk density is the most intuitive indicator to distinguish between light and heavy calcium, and the numerical difference is clear at a glance:
The bulk density of heavy calcium carbonate is relatively high, with a conventional range of 0.8-1.3g/cm ³;
Light calcium carbonate has a lower bulk density, typically ranging from 0.5 to 0.7 g/cm ³, with nanoscale light calcium carbonate even as low as 0.28 g/cm ³.
Ⅲ. Classification of particle size grades based on settlement volume
Definition of sedimentation volume: Add 1g of calcium carbonate to 100mL of water, shake thoroughly and let it stand for 3 hours. The larger the value, the finer and lighter the particle size of the powder, and the higher the product quality.
The settling volume of heavy calcium is only 1.1-1.4mL/g;
The sedimentation volume of ordinary light calcium can reach 2.4-2.8mL/g, while that of nano light calcium can reach 3.0-4.0mL/g.
Ⅳ. The specific surface area reflects the fineness of the powder
The specific surface area is directly related to the average particle size of the powder, and the higher the value, the finer the particles:
Heavy calcium: The specific surface area of ordinary products is about 1m ²/g, and that of fine heavy calcium is 1.45-2.1m ²/g;
Light calcium: The normal specification is about 5m ²/g, and the fine light calcium carbonate can reach up to 27-87m ²/g.
Ⅴ. Oil absorption value determines resin consumption cost
Oil absorption value is a key indicator for selecting fillers, which directly affects the amount of resin raw materials used in plastic products and coatings
1. The heavy calcium particles are coarse, smooth on the surface, have a small specific surface area, and have a low oil absorption value, mostly 40-60mL/100g, which can reduce resin consumption and lower production costs;
2. Light calcium particles are small, with a rough and uneven surface, a large specific surface area, and a higher oil absorption value, ranging from 60-90mL/100g. More resin is required to infiltrate the powder during processing.
Ⅵ. Each whiteness interval has its own advantages and disadvantages
The impurity content of ore determines the upper limit of powder whiteness:
Heavy calcium relies on natural ore processing, with higher impurity content, conventional whiteness of 89% to 93%, and high-quality products with a maximum of only 95%;
Light calcium is chemically purified to achieve higher purity, with a basic whiteness of 92% to 95%. High end refined products can reach 96% to 97%, making it more suitable for products with strict whiteness requirements.
Ⅶ、 Different stability of moisture content
There is no wet chemical process in the processing of heavy calcium, and the moisture content is stable and low, usually ranging from 0.2% to 0.3%. The moisture content of high-end ultrafine products can be controlled up to 0.1%;
Light calcium needs to be dehydrated and dried, with greater fluctuations in moisture content. The conventional moisture content is 0.3% to 0.8%, making it more prone to excessive moisture during storage and processing.
Ⅷ. The difference in particle size grading range is large
Heavy calcium carbonate
The particle size range is 0.5-45 μ m, divided into coarse grinding (>3 μ m), fine grinding (1-3 μ m), and ultrafine grinding (0.5-1 μ m) according to particle size; At present, it is not possible to industrialize the mass production of pure nanoscale heavy calcium, and only a small amount of fine products contain trace amounts of 100nm particles. The finer the particle size, the higher the selling price.
Precipitated Calcium Carbonate
The particle size range is wider, with ordinary products ranging from 0.5~15 μ m and nano light calcium only from 20~200nm. The subdivision grades include fine particles (>5 μ m), micro powders (1-5 μ m), micro powders (0.1-1 μ m), ultrafine particles (0.02-0.1 μ m), and ultrafine particles (<0.02 μ m), which can accurately match the requirements of fine modification.
Ⅸ. The particle morphology and structure are completely different
Heavy calcium powder
The particles have irregular shapes, sharp edges, rough surfaces, wide particle size distribution, and uneven sizes; Grinding only changes the particle size and does not alter the crystal structure. Calcite based heavy calcium is in hexagonal crystal form, while marble based heavy calcium is mostly in cubic crystal form, and the crystal morphology is determined by the ore origin.
Artificial synthesis of controllable crystals of light calcium powder, with regular particle morphology, narrow particle size distribution, and good monodispersity; By adjusting the reaction conditions, multiple crystal forms can be produced, suitable for different industries:
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Spindle shape: the most common light calcium crystal form, with a long axis of 5-12 μ m and a short axis of 1-3 μ m;
Needle shaped/chain shaped: particle size of 0.01-0.1 μ m, with aspect ratios of 5-100 and 10-50, respectively;
Spherical: particle size 0.03-0.05 μ m; Cube shape: 0.02-0.1 μ m; Flake: 1-3 μ m.
Ⅹ、 Difference in odor of food grade products
Odor is an important quality control standard in food filling scenarios: incomplete carbonation of light calcium carbonate in the production of calcium oxide will result in residual lime irritating odors, which can cause choking when used in baked goods such as biscuits; Heavy calcium carbonate has no additional odor, making food filling safer.
Ⅺ. Comparison of Production Costs and Environmental Performance
1. Preparation cost: The basic processing cost of conventional light and heavy calcium is similar. If combined with environmental protection and resource consumption costs, the comprehensive production cost of light calcium is higher;
2. Environmental emissions: The production of heavy calcium only produces noise pollution, with no discharge of wastewater, exhaust gas, or waste residue, making environmental control difficult; The calcination process of light calcium will generate a large amount of combustion exhaust gas, accompanied by the production of solid waste and wastewater, which requires greater investment in environmental protection and treatment;
3. Resource utilization: Heavy calcium can achieve comprehensive utilization of all components of ore, with high resource utilization rate; The chemical processing flow of light calcium is complex, making it difficult to accurately control the rational consumption of limestone resources.
Ⅻ. Comparison of actual application performance in various industries
Although both are filling powders, their functional positioning is different: heavy calcium mainly focuses on low-cost volume filling, with a high upper limit on the amount added; Light calcium combines filling and reinforcement, and nanoscale products can be used as functional modified fillers, with significant differences in performance across different industries.
1. Paper industry
After the popularization of neutral sizing technology, the demand for calcium carbonate has greatly increased. However, ordinary light calcium has strong oil and water absorption capabilities, which will consume more adhesive and reduce paper strength, making it unsuitable for ordinary printing paper; Spindle shaped light calcium is a specialized raw material for cigarette paper, with particles interlaced to form a loose bridging structure, significantly improving the breathability, opacity, and whiteness of the paper. It is the core filler for high-end cigarette paper; Regular writing and packaging paper should preferably use heavy calcium.
2. Plastic industry
Light calcium has a high oil absorption value and is difficult to mix and process. High filling systems are prone to poor dispersion; In high filling scenarios such as plastic pipes, woven bags, injection molding, and hollow products, heavy calcium is commonly used to reduce raw material costs.
3. Rubber industry
The particle size of light calcium is fine and the settling volume is large. Adding it can expand the volume of rubber, optimize the vulcanization process, and have a semi reinforcing or even reinforcing effect; Heavy calcium is only used as a low-cost incremental filler, with weak reinforcement performance.
4. Coatings, feed, and building materials fields
For products such as building putty, ordinary coatings, and feed fillers that do not require high powder fineness, heavy calcium carbonate is preferred for higher cost-effectiveness.
Summary
Heavy calcium carbonate is superior in terms of low production cost, low environmental pressure, stable moisture content, high filling adaptability to rubber and plastic pipes, ordinary papermaking, and building materials; The advantages of lightweight calcium carbonate include higher whiteness, controllable particle size, and diverse crystal forms, making it suitable for cigarette paper, rubber reinforcement, high-end coatings, and fine modified plastic products. Nano lightweight calcium is an indispensable filler for functional composite materials. When selecting a company, it can combine the product's requirements for reinforcement, whiteness, filling amount, and processing cost, and match the corresponding calcium carbonate category to achieve a balance between product performance and production cost.
