How to Review Calcium Carbonate Analysis?

Introduction to Calcium Carbonate Analysis and Its Importance in Industry

Calcium carbonate with the chemical formula CaCO₃ is one of the most abundant and well-known minerals in manufacturing industries. Due to its affordable price, abundance in nature, and diverse physical and chemical properties, this material is used in a wide range of products; from PVC/UPVC profiles and pipes and masterbatch to cables, artificial leather, paint, paper, glue, and engineered stone. But this wide range of applications shows that a single product caot meet the needs of all industries, and each application requires its own specific specifications.

Calcium carbonate analysis is actually a set of quantitative and qualitative data that shows how pure this material is, what dimensions its particles have, which impurities exist in it, and how this material will behave in the production process. This information is usually provided by the manufacturer in a sheet called the Analysis Sheet. But having this sheet alone is not enough; what matters is the ability to read, understand, and interpret this data. Without familiarity with concepts such as purity percentage, particle size distribution, and units of measurement, the figures and numbers listed lose their practical value.

The importance of reviewing the analysis can be examined from two aspects. First, the quality of your final product is directly affected by the specifications of the calcium carbonate used; particle size, their distribution, and material purity affect impact resistance, final surface quality, production speed, and even energy consumption. Second, carefully reviewing the analysis helps you create a proper match between your production line's actual need and the product available in the market, avoiding paying extra costs for a degree of quality you don't need. In other words, analysis is a decision-making tool, not a display sheet.

The calcium carbonate product of the Kani Sang Amiran project is produced in the 100 to 3500 mesh range and is selected for polymer, paint, paper, and engineering product applications. This diversity in particle size doubles the necessity of familiarity with analytical parameters; because a product suitable for engineered stone is not necessarily the best option for paper or masterbatch. Each application demands its own mesh range and surface characteristics, and reviewing the analysis is a bridge between the application need and the selection of the right product.

In this educational, step-by-step article, in simple and practical language, we will review the key concepts of analysis review: from purity percentage and particle size distribution to instrumental methods such as XRF and XRD, coating and moisture inspection, interpreting results based on industrial application, and finally a practical checklist for selecting a supplier. By the end, the reader will be able to review an analysis sheet with a professional perspective. To view the full product specifications, you can also visit the Calcium Carbonate page on the Kani Sang Amiran website.

Key Parameters to Check in Calcium Carbonate Analysis

To professionally review calcium carbonate analysis, you first need to know which parameters matter and what each one tells you about product quality. Below, we introduce the most important parameters usually included in the analysis sheet of mineral products so you can approach data interpretation with a broader perspective.

• Purity Percentage (CaCO₃ %): Indicates the amount of pure calcium carbonate in the product and is the most important overall quality indicator.
• Particle Size Distribution (PSD): Expresses particle dimensions and their dispersion as values like d10, d50, d90, and d97.
• Whiteness and Brightness: Optical properties of the product, especially important in paint, paper, and masterbatch.
• Moisture: The amount of water in the powder, affecting processability and product shelf life.
• Acid Insoluble Matter: Indicates impurities such as silicates and silty particles.
• Loss on Ignition (LOI): Shows the weight loss of the sample at high temperature and forms the basis for purity estimation.
• Oil Absorption: Indicates the amount of oil absorbed by the powder, important in paint and plastic applications.
• Specific Density and pH: Physicochemical properties that determine product behavior in formulation.
• Coating Type and Amount: In coated products, specifies the type of coating material and the degree of particle coverage.

Each of these parameters alone provides part of the overall picture of product quality. For example, high purity alone does not guarantee quality in a polymeric application; because coarse particles or improper size distribution can ruin the final surface of the product or reduce production line speed. For this reason, reviewing the analysis should always be a comprehensive and holistic view, not evaluating a single parameter in isolation. In fact, correct interpretation of analysis is the art of combining data to reach a purchasing decision.

Also, a key point to note is that the importance of each parameter varies depending on your application. In the production of PVC/UPVC profiles and pipes, particle size distribution and coating status are more important; while for paper and paint, whiteness degree and oil absorption play key roles. In cables and artificial leather, particle surface behavior and moisture level are decisive. Knowing your production line's needs is the first step to correctly interpreting the analysis and avoiding selection errors.

Finally, it is recommended to always define the analysis data in the form of a written specification sheet for your supplier so that what you receive is exactly what your production line needs. In addition to maintaining quality, this minimizes potential disputes in product delivery and forms a transparent business relationship. In the next chapter, we will examine the most important parameter, namely purity percentage and its measurement methods, in detail.

Calcium Carbonate Purity Percentage and Measurement Methods

Purity percentage is the most and at the same time most frequently referenced parameter in calcium carbonate analysis. This number shows what fraction of the product mass is pure calcium carbonate, and the rest is impurities such as silica, metal oxides, and organic matter. In sensitive applications, a few percent difference in purity can mean a difference in final product quality and even increased production line waste.

There are various methods to measure purity. The most common method is complexometric titration with EDTA, which is based on the reaction of calcium ions with EDTA reagent in the presence of a color indicator. In this method, the volume of EDTA consumed to reach the endpoint is the basis for calculating calcium percentage and consequently calcium carbonate percentage. This method has adequate accuracy, low cost, and wide availability in quality control laboratories.

Another method is X-ray fluorescence (XRF). In this method, the sample is exposed to X-rays and its constituent elements are identified and measured based on the wavelength of the retuing beams. XRF has high speed and can analyze various elements simultaneously; therefore, it is widely used in daily quality control by mineral material producers. The output of this device is the percentage of constituent oxides such as CaO, which is converted to CaCO₃ percentage with a conversion factor.

The third method is determining loss on ignition (LOI). Calcium carbonate decomposes at high temperature and converts to calcium oxide and carbon dioxide gas. Measuring the weight loss of the sample after heating is the basis for estimating calcium carbonate percentage. This method is simple, but it should be noted that other volatile substances can also affect the number; therefore, it is usually used as a supplementary test and not exclusively for consumption.

In addition to direct purity methods, the acid insoluble matter test also provides complementary information. In this test, the sample is dissolved in acid and the part that does not dissolve (mostly silicates and silty particles) is weighed. The lower this value, the higher the product purity. Combining the results of these tests gives you a reliable picture of raw material quality. Also, to lea about the signs of identifying original and fake products, read the article How to Identify Original Calcium Carbonate Powder?

An important point in reviewing the purity number is to always ask the supplier for the test method and reference standard. Two different methods can give different numbers for the same sample, and comparing the analysis of two suppliers without knowing the test method would be an incorrect comparison. Also, request that the test results be provided on your specific sample, not just the general product sample, to ensure that the number stated in the analysis represents the product you will actually receive. An independent laboratory can also be used as an arbitration reference in sensitive cases.

Particle Size Distribution and the Role of Mesh in Product Quality

After purity, particle size distribution (PSD) is the most important analytical parameter. This parameter shows what dimensions the product particles have and how they are spread over a size range. In polymeric, paint, and paper applications, particle size directly affects how the material disperses in the matrix, final product surface quality, transparency, and mechanical strength, and is therefore considered a decisive parameter.

In analysis sheets, particle size distribution is usually expressed with values like d10, d50, d90, and d97. The number d50 means that 50% of the particle mass is smaller than this size; similarly, d97 means 97% of the particle mass is smaller than this value. The smaller the d97, the finer and more uniform the product. To evaluate product quality, a single number is not enough; rather, the entire distribution curve and its uniformity must be considered to ensure the absence of coarse particles.

The common unit for expressing particle size in the Iranian market and many global markets is "Mesh". The mesh number indicates the number of holes per inch of the sieve; so that a higher mesh number means finer particles. The calcium carbonate product of Kani Sang Amiran is offered in the 100 to 3500 mesh range; a range that covers almost all common industrial applications. Lower grades are usually suitable for applications like engineered stone and glue, while higher grades are used for masterbatch, paper, and paint.

The standard method for measuring PSD is laser diffraction. In this method, a laser beam passes through the particle suspension and the obtained scattering patte is converted into a size distribution curve based on mathematical models. This method is fast, repeatable, and requires precise sampling and preparation. In very fine grades, other methods such as image analyzers or scaing electron microscopes can be used to confirm results.

The effect of particle size on product performance is very direct. In PVC/UPVC profiles and pipes, finer particles with uniform distribution create a smoother final surface and higher impact resistance. In masterbatch, finer particles help better color dispersion and more transparency. In paper, fine particles create better coating. But it should be noted that finer is not always better; excessively fine particles may cause increased oil absorption, reduced line speed, and processing problems. Choosing the right size is a balance between final product quality and production process efficiency.

As a summary of this chapter, when reviewing the PSD section of the analysis, always check three points: first, that d50 and d97 values are all specified and listed; second, that the distribution curve is uniform and has no coarse (oversize) particles; and third, that the measurement method (e.g., laser) and sample preparation conditions are mentioned in the analysis sheet. These three simple points identify many potential production problems before they occur.

Instrumental Methods for Calcium Carbonate Analysis (XRF, XRD, FTIR)

To accurately and reliably examine calcium carbonate, in addition to classical chemical methods, advanced instrumental techniques are used. These methods provide much richer information about the structure, composition, and characteristics of the product and play a vital role in verifying the quality of high-value products. Below, we review the most important of these methods.

X-ray Fluorescence (XRF): In this method, the sample is bombarded with X-rays and the constituent elements are identified and quantified based on the retuing fluorescence beams. XRF is very efficient for determining the percentage of main oxides such as CaO, SiO₂, Fe₂O₃, Al₂O₃, and MgO, and is used as a fast, non-destructive, and repeatable method in daily quality control. Its output is usually provided as a percentage of elements or oxides, and with conversion factors, the calcium carbonate percentage can be calculated.

X-ray Diffraction (XRD): This method examines the crystalline structure of the material and can determine which crystalline form (polymorph) of calcium carbonate is present: calcite, aragonite, or vaterite. In polymeric applications, the crystalline form and structure can affect the material's behavior in formulation. XRD can also identify impurity phases such as quartz or dolomite and is considered a reference tool to confirm that the sample is truly the desired type of calcium carbonate.

Fourier Transform Infrared Spectroscopy (FTIR): This method identifies the chemical bonds and functional groups of the material. In calcium carbonate, FTIR shows specific absorption bands of the carbonate ion and can easily detect the presence of organic matter, silicates, or other impurities in the sample. FTIR is also a useful tool for examining the amount and type of coating in coated products, as it shows fatty acid bonds on the particle surface.

Scaing Electron Microscope (SEM): Used to examine the shape, morphology, and actual size of particles. SEM images provide information about particle shape (spherical, acicular, prismatic) and the uniformity of milled products, which is valuable in applications where particle morphology affects final product behavior (such as painting and paper coating). In some cases, automated image analyzers are used for more complete statistics on particle size and shape distribution.

Choosing the appropriate method depends on what information is needed: for daily purity control, XRF or titration is sufficient; to confirm crystalline structure and type of calcium carbonate, XRD; to identify organic matter and coating, FTIR; and to directly view particles, SEM. In important projects, a combination of several methods is usually used for full validation of results. The laboratory's reference status and the alignment of methods with recognized standards increase confidence in the accuracy of analytical data and lead to a reliable choice.

Checking Moisture, Coating, and Surface Characteristics

In addition to chemical composition and particle size, the surface characteristics and moisture of calcium carbonate play an important role in its performance. These parameters determine how the material interacts with other formulation components (especially polymers and solvents) and how it behaves on the production line. Careful examination of this part of the analysis is a key step in selecting the right product.

Moisture is one of the critical parameters in powder products. Free water in the powder can cause bubbles, porosity, and a drop in final product quality in polymeric processes; in paint and glue, high moisture can damage suspension stability and product shelf life. Moisture measurement methods include oven drying (gravimetric) and the Karl Fischer method for very low moisture. In the oven method, the sample is dried at a specific temperature until reaching constant weight, and the weight loss is reported as moisture.

Coating is one of the most important mode developments in calcium carbonate products. In coated products, the particle surface is covered with a thin layer of organic materials (usually fatty acids such as stearic acid). This layer makes the particles hydrophobic and more compatible with the polymer matrix. The result of this is better particle dispersion, reduced oil absorption, reduced extruder torque, and improved mechanical specifications of the final product.

There are several methods to examine the amount and quality of coating. FTIR can confirm the presence of organic bonds from fatty acids on the particle surface. Contact angle measurement shows the degree of particle hydrophobicity. Also, the oil absorption rate before and after coating can be an indicator of coating quality. A good coated product should have uniform coating dispersion on all particles, not just some particles being coated.

The importance of coating in polymeric applications, especially in PVC profiles, masterbatch, and cables, is very prominent. Without proper coating, calcium carbonate particles tend to agglomerate, which causes a drop in impact resistance and surface defects. To better understand the role of coating in polymers, read the article How Does Coated Calcium Carbonate Help Polymer Thermal Stability?

Other surface characteristics such as pH and specific density are also considered in the analysis review. The pH of calcium carbonate is usually in the weakly alkaline range, and this must be considered in acid-sensitive formulations. Specific density affects volumetric filling and weight-volume ratio calculations in formulation. Ultimately, the consistency of these characteristics across different product batches indicates the supplier's stable quality control and should be checked periodically.

Interpreting Analysis Results Based on Industrial Application

One of the most important skills in reviewing calcium carbonate analysis is the ability to match its results to the needs of your specific application. In this chapter, we examine the most important applications of this mineral and the parameters that are most important in each, so that reviewing the analysis becomes a targeted process for you.

PVC/UPVC Profiles and Pipes: In this application, calcium carbonate is used both as a filler and as a cost-reducing agent. Uniform particle size distribution is vital for achieving a smooth surface and higher gloss; coarse particles cause a significant drop in gloss and impact resistance. The presence of controlled-size particles helps better melt flow and higher production speed. Proper coating is also essential to prevent particle agglomeration and compatibility with the PVC matrix. Follow the improvement of polymeric products' resistance with coated calcium carbonate in the article How Does Coated Calcium Carbonate Increase the Resistance of Polymeric Products?

Masterbatch and Cables: In masterbatch production, high whiteness degree and fine, uniform particle size distribution are extremely important, because calcium carbonate acts as a filler and color carrier, and any impurities or coarse particles directly affect the color quality and transparency of the final product. In the cable industry, electrical and insulation properties are important, and metallic impurities and moisture must be minimized, because metal ions and free water can seriously damage the cable's insulation specifications.

Paint and Artificial Leather: In the paint industry, oil absorption and whiteness degree are key parameters. Low oil absorption means lower solvent consumption and higher pigment volume in the formulation. In artificial leather, which is made from polymers like PVC and polyurethane, particle uniformity and proper surface behavior are decisive for achieving the desired texture and abrasion resistance.

Paper, Glue, and Engineered Stone: In papermaking, calcium carbonate is used both as a filler and in coating, and very fine particles with uniform distribution are needed to achieve smooth, white, and printable paper. In glue, products with different mesh grades are selected based on the glue type and final application. In engineered stone, medium mesh grades with sufficient purity and light color are usually used, because in this application, high volume and economical product price matter more than particle fineness.

As a summary, in any application, before reviewing the analysis, first prepare a specification sheet of your critical parameters: target purity, allowable particle size range, minimum whiteness degree, allowable moisture, and coating need. Then evaluate the analysis of candidate products against this specification sheet. This systematic method prevents decision-making based on supplier price or advertisements and guarantees a choice based on your production line's actual need.

Final Checklist for Analysis Review and Supplier Selection

In the final chapter, we organize everything we reviewed into a practical checklist for reviewing analysis and selecting a calcium carbonate supplier. This checklist can be used as a step-by-step guide when receiving the analysis sheet for any new product.

• The test method and reference standard for each parameter should be specified.
• The purity percentage should be measured and listed using a reliable method (titration, XRF, or LOI).
• The values d10, d50, d90, and d97 should be presented completely, not just a single average number.
• The particle size distribution curve should be uniform and without coarse (oversize) particles.
• The whiteness and brightness degrees should be listed for paint, paper, and masterbatch applications.
• The moisture amount should be measured with a standard method (oven or Karl Fischer).
• Acid insoluble matter should be low and within the allowable range for your application.
• If using a coated product, the type and amount of coating should be specified and verifiable.
• The results should pertain to the product sample you will actually receive, not a general sample.

Key Questions for the Supplier: First, can you provide test results on my specific sample? Second, can the particle size range be adjusted based on my needs? Third, how do you guarantee consistency between batches? Fourth, is it possible to provide a trial sample for evaluation on the production line? These questions help you distinguish a supplier who only shows an analysis sheet from one with real quality control.

Batch-to-batch consistency is one of the most important indicators of a professional supplier. Receiving several batches of product over time and comparing their analysis shows whether the manufacturer has stable quality control. Large fluctuations in particle size or purity, even with a good average, can cause production problems on your line. Therefore, it is recommended to evaluate at least three batches of product at different time intervals.

Ultimately, remember that a good analysis is your most important tool in selecting a suitable calcium carbonate for your production line. A product that precisely meets your application requirements will, in the long run, bring significant savings through reduced waste, improved quality, and production speed. The Kani Sang Amiran project, by offering products in the 100 to 3500 mesh range and broad industrial applications, is ready to provide you with transparent technical and analytical information so you can choose the right product for your needs with complete confidence.

Finally, it is recommended to keep this checklist in the form of a written form in your company's technical archive and complete it step by step during each new product evaluation. In addition to creating a traceable record, this makes the raw material purchasing process independent of specific individuals and creates an organizational standard procedure. Choosing the right raw material lays the foundation for the quality of your final products.

Source: Kani Sang Amiran Project (Mineral Materials Production) — Calcium carbonate product data and common mineral testing standards.