• Fineness: 325 mesh (Screen)
• Corresponding particle size: Approximately 45 micrometers (μm)
• Standard pass rate: ≥ 99.5% passes through 325 mesh sieve
• Main component: CaCO₃ (Calcium carbonate)
• Common type: Heavy calcium carbonate (Ground Calcium Carbonate, GCC)
• Appearance: White powder
• White degree: Industrial grade usually 85%–93%
• Density: Approximately 0.8–1.0 g/cm³
• pH value: 8–10 (weakly alkaline)

• Chemical stability: Highly inert, resistant to acids and alkalis, non-toxic and odorless.
• High cost-effectiveness: Moderate fineness, processing, and raw material costs are much lower than those of ultra-fine powders (e.g., 800 mesh, 1250 mesh).
• Good filling property: Enhances the product’s hardness, heat resistance, and dimensional stability, and significantly reduces raw material costs.
• Easy to disperse: Good dispersibility in plastic, rubber, coating and other systems.

What are the main applications of 325 mesh calcium carbonate powder?

• Plastics: PVC pipes/profiles, sheets, cable materials, injection molded products (cost reduction, increased rigidity, and heat resistance).
• Coatings / Paints: Latex paint, primer, putty (body filler, enhancing coverage and paint film thickness).
• Rubber: Shoe soles, rubber products (reinforcement filling, improving processing performance).
• Building materials: Dry powder mortar, sealant, and glass adhesive (increasing consistency and filling ability).
• Papermaking: Fillers, coating pigments (improving paper whiteness, smoothness, and opacity).

1. Heavy Calcium Carbonate (GCC, 325 mesh) – Most commonly used
   Common industrial grade (whiteness 85% – 90%, CaCO₃ 96% – 98%)
   40 – 55 USD / ton
   (For power plant desulfurization, ordinary putty, low-grade plastics, building materials, and mortar)
   High whiteness / Premium grade (whiteness 90% – 94%, calcite raw material)
   55 – 80 USD / ton
   (Coatings, PVC, cable materials, papermaking, rubber)
   Superior / Ultra-white (whiteness 95% +, high-purity calcite)
   100 – 150 USD+ / ton
   (High-end coatings, food / pharmaceutical grade, special modification)
2. Lightweight Calcium Carbonate (PCC, 325 mesh)
   Common light calcium: 60 – 100 USD / ton
   Active / Modified light calcium: 100 – 150 USD / ton

The most common types of processing equipment available on the market are these two：

From the above introduction, we have learned that both the Raymond mill and the ultra-fine grinding machine can be used to process calcium carbonate powder with a particle size of 325 mesh. So, what are the differences between these two devices? What are the differences in their working principles?

Now, let our technical engineer answer your questions for you.

Raymond mill-The preferred choice for processing 325 mesh calcium carbonate：

The Raymond mill is composed of a single layer of grinding rings. Usually, a Raymond mill can consist of 3 to 5 rollers. These rollers are the parts that come into direct contact with the materials. They lift the mineral powder using scrapers and grind the powder through the compression between the rollers and the grinding rings. However, the fineness of the products processed by this type of equipment is relatively low, typically ranging from 80 mesh to 400 mesh. It is suitable for enterprises that do not have strict requirements for product fineness. This equipment has a relatively low cost, especially more favorable for mining business owners who are just starting out. Currently, our small-sized Raymond mill 4R3220 is very popular in Nigeria.

ultrafine grinding mill：

Schematic diagram of the working principle of the ultrafine grinding mill

The ultra-fine grinding machine uses a multi-layer crushing method to grind the mineral powder. The mineral materials are fed into the main body of the grinding machine through the feeding machine, and after multiple layers of crushing, the mineral powder is ground into ultra-fine powder with a size of 300-3000 mesh or larger.

The fineness of the finished product, ranging from 300 to 3000 mesh, is achieved by adjusting the rotational speed of the analyzer. The mineral powder that has undergone ultra-fine grinding processing is mainly applied in industries such as plastic fillers, high-end paints, PVC fillers, and high-end coatings.

Many mine owners do not know how to choose grinding equipment. They may not be wise to solely pursue high fineness. High-fine grinding machines are relatively expensive, and many customers’ end-users do not necessarily require such high-fine mineral powder. Here are several selection suggestions provided by Cronus’ engineers for your reference:

• To fully understand the fineness of the mineral powder your customers require, if it is below 400 mesh, then the Raymond mill should be chosen. If the fineness requirement is generally above 600 mesh, then a superfine grinding machine should be selected.

• Decide based on the investment situation: For the initial investment, it is relatively small. You can choose the Raymond mill. Starting with an investment of around 50,000 US dollars is sufficient. If the investment is adequate and the main customers all have a demand for ultra-fine powder, then choose the ultra-fine grinding machine.
• Long-term planning: The main consideration is the future uses of the mineral powder and the main application fields. Based on the understanding of the market, an ultra-fine grinding machine can be selected.

• Optimal combination: The optimal configuration includes installing a Raymond mill to meet the needs of customers requiring coarse powder, as well as installing an ultra-fine powder machine to satisfy the demands of high-end customers.

If you are interested in the equipment, please feel free to contact us.

You can also visit our official website to learn more.

www.shcronus.com