Feasibility Study on Marble Grinding with Raymond Mill and Applications of the Ground Powder

1. Project Overview

Marble is a metamorphic rock formed from pre‑existing rocks subjected to high temperature and pressure. It is mainly composed of calcite, limestone, serpentine, and dolomite, with calcium carbonate (CaCO₃) as the primary component, typically accounting for more than 50%. Marble resources are widely distributed and easy to process. With economic development, the domestic and international demand for marble powder has been growing steadily. Using Raymond mills to grind marble is an effective way to convert marble resources (including waste materials from mining and processing) into high‑value‑added industrial raw materials.

2. Raw Material Analysis

2.1 Basic Properties of Marble

• Main component: Calcium carbonate (CaCO₃), typically >90%
• Mohs hardness: 3–4 (well below the Raymond mill’s upper limit of 7)
• Densità: 2.6–2.8 g/cm³
• Colour: white, greyish white, light red, light green, etc.; whiteness can reach 85–93 or higher
• Moisture content: generally <1% (meeting the Raymond mill requirement of <6%)

2.2 Raw Material Sources

Raw materials for marble grinding are abundant and include:

1. Run‑of‑mine marble blocks from quarries – after primary crushing, they can be fed directly to the mill
2. Edge scraps and waste from marble processing plants – generated during cutting and polishing; approximately 70% of marble resources become tailings or waste during mining and processing
3. Demolished marble construction waste – marble waste from old building demolition

Using marble waste for grinding not only enables resource recycling but also reduces environmental pollution, aligning with the national strategy for a green circular economy.

3. Working Principle of Raymond Mill and Its Suitability

3.1 Working Principle

The Raymond mill (pendulum roller mill) is a vertical fixed‑disc mill primarily used for grinding various non‑metallic ores. The process is as follows: large materials are crushed by a crusher to the required size, then elevated by a bucket elevator to a storage hopper, from which an electromagnetic vibrating feeder uniformly and continuously delivers the material into the grinding chamber. Driven by the transmission device, the central shaft rotates the plum blossom frame and the roller assembly, generating a strong centrifugal force that presses the rollers tightly against the grinding ring. The material is scooped up by a plough blade and fed between the rollers and the ring, where it is crushed by rolling, squeezing, and impact. The ground powder is carried by air flow upward to the classifier, where a turbo classifier separates the fines. Particles meeting the fineness requirement are carried into a cyclone collector for collection, while oversize particles are returned to the mill for re‑grinding.

3.2 Suitability for Marble

Marble fully meets the operating conditions of Raymond mills:

4. Process Flow

4.1 Complete Production Process

Marble ore / waste
       ↓
Frantoio a mascelle (primary crushing to ≤30 mm)
       ↓
Bucket elevator
       ↓
Storage hopper
       ↓
Electromagnetic vibrating feeder (uniform feeding)
       ↓
Raymond mill (grinding)
       ↓
Turbo classifier (classification)
       ↓
Qualified fine powder → Cyclone collector → Packaging
Oversize particles → Return to mill for re‑grinding
       ↓
Pulse bag filter (collection efficiency ≥99.9%)

4.2 Description of Each Step

(1) Crushing

Large marble blocks (typically >300 mm) are crushed by a jaw crusher to below 30 mm to meet the feed size requirement of the Raymond mill. For marble edge scraps that are already 15–50 mm, the crushing step may be omitted.

(2) Conveying and Storage

The crushed material is conveyed by a bucket elevator to a storage hopper, which acts as a buffer to ensure continuous feeding.

(3) Feeding

An electromagnetic vibrating feeder delivers the material uniformly and quantitatively from the hopper into the grinding chamber. Stable feed rate directly affects product quality and equipment performance.

(4) Grinding

The material is crushed by rolling, squeezing, and impact between the rollers and the grinding ring. Key parameters during grinding include roller pressure and main shaft speed, which should be adjusted according to the target fineness.

(5) Classification

The ground powder is carried upward by air flow to the classifier. The turbo classifier separates the fines; those meeting the fineness requirement pass through, while oversize particles are returned to the mill. Classification accuracy directly determines product quality.

(6) Collection and Packaging

Qualified powder is carried by air into the cyclone collector for gas‑solid separation. The collected finished powder is discharged through the powder outlet and sent to packaging. Packaging can be in tonne bags or small bags, depending on customer requirements.

(7) Dust Collection System

The entire system is equipped with a pulse bag filter, achieving a collection efficiency of over 99.9%. The air‑classification circuit circulates internally between the fan, cyclone separator, ducting, and fan. Minimal dust is emitted, keeping the workshop clean and environmentally friendly.

5. Equipment Selection

5.1 Main Equipment Configuration

5.2 Raymond Mill Model Selection

5.3 Option for Ultra‑fine Grinding (Optional)

For producing ultra‑fine marble powder (800 mesh or finer), a high‑fineness ring roller mill can be selected:

5.4 System Characteristics

The Raymond mill grinding line has a compact three‑dimensional structure, small footprint, and strong system integration. From raw material preparation to grinding to final packaging, it forms an independent production system. The finished powder is uniform in fineness, with a screening pass rate of 99%.

6. Product Quality and Fineness Control

6.1 Fineness Adjustment Range

Raymond mills can produce marble powder with fineness adjustable within 80–600 mesh (0.18–0.038 mm). Some upgraded models can reach 800 mesh. When using a high‑fineness ring roller mill, fineness can be adjusted between 325 and 2500 mesh, with product fineness reaching D97 ≤ 5 μm in a single pass.

6.2 Product Types by Fineness

7. Applications of Ground Marble Powder

Marble powder (mainly calcium carbonate, CaCO₃) has high whiteness, good purity, stable chemical properties, and is non‑toxic and odourless. Ground marble powder (ground calcium carbonate, GCC) is widely used in the following fields:

7.1 Plastics Industry

Marble powder is used as a filler in plastic products to increase volume, improve processing properties (adjusting viscosity and rheology), and reduce costs. Different fineness grades are used in PVC, PE, and other plastic products. The plastics industry is one of the largest consumers of calcium carbonate, accounting for a significant share of downstream demand.

• Fineness: 250–300 mesh
• Applicazioni: Filler for PVC profiles, pipes, cable compounds, plastic films, etc.

7.2 Paints and Coatings

Marble powder is used as a filler to improve hiding power, durability, and application properties. It is mainly used in interior/exterior wall paints, waterproofing materials, and industrial coatings.

• Fineness: 325–800 mesh
• Applicazioni: Latex paints, putty powders, waterproof coatings, road marking paints, etc.

7.3 Paper Industry

As a paper filler, marble powder improves paper whiteness, opacity, and printability. The paper industry is a major consumer of GCC.

• Fineness: 325–1250 mesh
• Applicazioni: Pre‑coating, top‑coating, and pulp filling in papermaking.

7.4 Building Materials

Marble powder has wide applications in building materials:

• Artificial agglomerated stone: Made from marble waste and powder with organic resin as binder, through vacuum mixing and high‑pressure vibration moulding. Hezhou, Guangxi, has developed a green industrial chain: “mining – natural stone – GCC powder – artificial stone”.
• Concrete admixture: Replacing 5%–40% of cement with waste marble powder improves abrasion resistance, compressive strength, and flexural strength.
• Putty powder: As a filler to improve workability and reduce cost.
• Imitation stone coatings: Marble powder can account for as much as 60%–70% of the formulation.

7.5 Rubber Industry

Marble powder is used as a filler in rubber products to improve processing and mechanical properties.

• Fineness: 250–400 mesh
• Applicazioni: Fillers for tyres, hoses, conveyor belts, seals, etc.

7.6 Adhesives and Sealants

Marble powder is used to adjust viscosity, increase volume, and reduce costs in adhesives and sealants.

• Fineness: 200–600 mesh
• Applicazioni: Construction sealants, silicone sealants, epoxy adhesives, etc.

7.7 Other Applications

• Cosmetics and personal care: Ultra‑fine marble powder with high whiteness and purity is used in cosmetics, toothpaste, etc.
• Food and pharmaceutical: Used in chewing gum, chocolate, and pharmaceutical excipients.
• Feed additives: As a calcium supplement.
• Desulphurisation agents: Marble powder is efficient and cost‑effective for flue‑gas desulphurisation.
• Soil conditioners: The alkaline nature of marble powder neutralises acidic soils.
• Wastewater treatment filter media: Used as a neutralising filter for acidic wastewater.

8. Environmental Protection and Safety

8.1 Dust Control

The Raymond mill system operates under negative pressure and is equipped with a pulse dust collection system. The pulse bag filter achieves a collection efficiency of over 99.9%. The air‑classification circuit is internal, so very little dust is emitted, keeping the workshop clean. Electrical systems are centrally controlled, and the mill can operate virtually unattended.

8.2 Noise Control

The mill mainframe can be equipped with vibration‑damping devices to reduce noise and vibration. The integral base structure is robust and offers good seismic resistance.

8.3 Safety Measures

• Overload protection and emergency stop devices are installed.
• Electrical systems have grounding protection.
• Explosion‑proof design for the powder collection system (marble powder is non‑flammable and non‑explosive, so risk is low).

9. Investment and Economic Analysis

9.1 Investment Estimation

The investment cost of a marble Raymond mill grinding line varies depending on equipment model, capacity, automation level, and auxiliary equipment:

Equipment prices vary significantly with configuration. For reference, the HC1300 model is around 400,000–500,000 RMB, HC1500 about 100,000–200,000 RMB, and HCH1395 ultra‑fine mill about 600,000–700,000 RMB. These are indicative prices; final quotes depend on specific configurations and supplier negotiations.

Additional costs include factory construction, power upgrades, installation, and commissioning, generally accounting for 30%–50% of total investment.

9.2 Operating Cost Analysis

Main operating costs include:

• Electricity: Total power ranges from 85 to 680 kW; electricity is the largest operating cost.
• Wear parts replacement: Rollers and rings are made from wear‑resistant materials and surface‑treated, but they are normal consumables.
• Labour: High automation reduces manpower requirements.
• Manutenzione: Maintenance‑free roller assemblies reduce maintenance time and cost.

9.3 Economic Benefits

• Low raw material cost: Utilising marble waste significantly reduces feedstock cost.
• High product added value: Marble powder (GCC) has strong market demand – domestic consumption in China was about 23.96 million tonnes in 2024, and is expected to continue growing through 2030.
• Policy support: The state encourages the development of ultra‑fine GCC (≤5 μm) and its wide application in building materials, environmental protection, plastics, rubber, coatings, etc.
• Broad market outlook: The global calcium carbonate market was valued at US$25.72 billion in 2024 and is projected to reach US$41.35 billion by 2033.

10. Risk Analysis and Mitigation