Comparative Analysis Between Raymond Mill and Vertical Roller Mill

Core standards referenced in this article: JB/T 13877-2020 Pendulum Mill, GB/T 35165-2017 Vertical Roller Mill for Non-metallic Ores, GB/T 50542-2019 Code for Design of Powder Engineering.

Working Principle Analysis of Raymond Mill and Vertical Roller Mill

Working Principle of Raymond Mill

Raymond Mill is a grinding device that uses centrifugal force to drive grinding rollers to compress materials. Its core components include vertical mainframe, plum blossom frame, shovels, grinding ring, grinding roller assembly, classifier, fan and pipeline system.

During operation, the grinding rollers mounted on the plum blossom frame rotate with the main shaft. Driven by centrifugal force, the rollers continuously press against the fixed grinding ring while rotating on their own axis. Meanwhile, the shovels installed below the grinding rollers rotate at high speed together with the plum blossom frame, scooping materials falling to the bottom of the main machine and throwing them between grinding rollers and grinding ring to form a material bed. After materials are crushed and ground by rollers, powder flows with air stream into the top classifier. Qualified fine powder passes the classification wheel and enters the collection system, while unqualified coarse powder falls back to the grinding zone for regrinding, forming a closed-circuit circulation system.

The fineness and output of finished powder are controlled by adjusting the classifier speed and system air volume. Higher rotating speed produces finer classified powder. Larger air volume strengthens air conveying capacity and brings more powder to the classifier per unit time, directly boosting output.

Note that excessive air volume may force coarse powder through the classification wheel and coarsen finished powder. Insufficient air volume fails to carry qualified fine powder out of grinding zone timely, which easily causes over-grinding, reduces output and accelerates wear of grinding rollers and rings. During production, air volume and classifier speed shall be matched and adjusted to pursue maximum output on the premise of guaranteed fineness.

Working Principle of Vertical Roller Mill

Vertical Roller Mill is a hydraulic constant-pressure bed grinding equipment integrating drying, grinding and classification functions. Its core structure consists of grinding table, grinding rollers, rocker arm assembly, hydraulic pressurization system, classifier, fan and pipeline system.

In operation, the motor drives the grinding table to rotate via reducer. Materials fall onto the grinding table through feeding inlet and move toward table edge under centrifugal force. At the same time, grinding rollers keep pressing the material bed on grinding table under hydraulic system and rotate by friction from materials. The rollers hang above the table without direct contact. Materials are crushed under extrusion and grinding between rollers and table.

While grinding, hot air entering from air ring dries materials synchronously. Fine powder is carried by hot air to the top classifier. Qualified fine powder passes classification wheel into collection system, and unqualified coarse powder returns to grinding zone for regrinding to build closed-circuit circulation.

The fineness and output of finished powder are also controlled by adjusting classifier speed and system air volume. Hot air temperature and air volume determine drying performance. In production, air volume and classifier speed should be coordinated, and balance between hydraulic pressure and material bed thickness shall be maintained to maximize output under stable operation and qualified fineness.

Performance Index Comparison Between Raymond Mill and Vertical Roller Mill

The following data are tested under identical working conditions with calcite, Mohs hardness 3, feed size ≤25mm, finished product 200 mesh with D97 pass rate ≥90%. Data for reference only. Actual parameters vary with raw materials and processes. Contact us for specific parameters; our professional technical team will provide support.

Energy Utilization

Raymond Mill: Grinding rollers tightly press grinding ring with metal contact during milling. Energy utilization rate ranges from 5%~8%, over-grinding rate ≤30%. Power consumption rises exponentially with fineness; power consumption exceeds 40kWh/t under 400 mesh condition.

Vertical Roller Mill: Grinding rollers do not contact grinding table directly, so metal loss is low. Energy utilization rate reaches 10%~15%, over-grinding rate ≤15%. It saves 25%~30% energy compared with Raymond Mill, with unit power consumption of only 20~28kWh/t.

Scale Application

Raymond Mill: Suitable for materials with Mohs hardness ≤7, optimal for medium & low hardness ≤4. Feed moisture ≤6%; pre-drying equipment is required for high-moisture materials. Feed particle size generally ≤30mm, single machine hourly output 0.3~35t/h, maximum annual capacity ≤300,000 tons. Scalability drops when output exceeds 10t/h. It is mainly used for small and medium powder processing. Large-scale projects usually adopt multi-machine parallel configuration.

Vertical Roller Mill: Wider adaptability, capable of handling materials with Mohs hardness ≤9.5. Powerful integrated drying eliminates extra drying equipment. Feed moisture ≤15% (special configuration up to ≤25%, e.g. GKLM coarse powder vertical roller mill). Feed size generally ≤50mm, single machine hourly output 2~420t/h, maximum annual capacity above 2 million tons. It is primary equipment for large-scale industrial powder production.

Finished Powder Fineness

Raymond Mill: Dynamic classification system (rotary impeller). Fineness range 80~400 mesh with uniform particle size distribution. Fitted with ultra-fine classifier or high-pressure suspension roller device, it can reach 600 mesh, but output declines above 400 mesh. Its efficient grinding interval remains 80~400 mesh.

Vertical Roller Mill: Combined dynamic-static classification system (dynamic rotor + static vanes). Fineness 80~600 mesh with concentrated particle size distribution and superior classification precision versus Raymond Mill. (Ultra-fine vertical mill reaches 2500 mesh)

Operation & Maintenance Cost

Raymond Mill: Low initial investment, only 1/3 of vertical roller mill. Service life of grinding roller and ring: 800~2500h, single downtime lasts 4~8h. High comprehensive cost performance.

Vertical Roller Mill: Higher initial investment but lower running energy consumption and maintenance cost, saving 25%~30% energy than Raymond Mill. Roller sleeves are reversible; service life of roller sleeves and table liners is 6000~12000h. O&M cost per unit output is merely 30%~50% of Raymond Mill, annual maintenance downtime reduced by over 70%, delivering high ROI in long-term operation.

How to Choose Between Raymond Mill and Vertical Roller Mill?

There is no absolute superiority between Raymond Mill and Vertical Roller Mill. Matching proper application scenarios and material characteristics is the key to efficient production.

Optimal Application Scenarios of Raymond Mill

Production Scale: Small-medium projects with annual capacity ≤100,000 tons and rated hourly output ≤5t/h, or project pilot and temporary production lines.

Material Characteristics: Dry, medium-low hardness non-metallic minerals with Mohs hardness ≤4 and feed moisture ≤6%, e.g. limestone, dolomite, calcite.

Quality Requirements: General powder products without strict requirements for particle distribution and purity, such as construction powder and common building material additives.

Project Profile: Small & medium private enterprises with limited budget, short ROI cycle and site constraints.

Optimal Application Scenarios of Vertical Roller Mill

Production Scale: Medium-large projects with annual capacity ≥100,000 tons and rated hourly output ≥5t/h, especially large industrial projects requiring continuous and stable production.

Material Characteristics: Medium-high hardness, highly abrasive materials with Mohs hardness ≥4 or high-moisture materials with feed moisture ≥6%, such as slag, steel slag, cement raw meal and clinker.

Quality Requirements: High-end powder products with strict standards for particle distribution, whiteness, purity and qualification rate, e.g. functional fillers for plastic, coating, paper-making, rubber, high-grade building material powder.

Project Profile: Large enterprises or group projects with sufficient capital, focus on long-run operation cost and long-term ROI.

Frequently Asked Questions About Raymond Mill and Vertical Roller Mill

Advantages and Disadvantages of Multi Raymond Mills in Parallel vs Single Vertical Roller Mill?

Multi Raymond Mills in Parallel: Low investment threshold and high fault tolerance. Funds can be invested in phases, with lower total cost than a single vertical roller mill. Production continues on remaining units if one stops, minimizing capacity risk. It supports multi-product production (e.g. two units for 200 mesh, two for 325 mesh) to flexibly handle small-batch, multi-batch orders for diverse industries. However, its process system is complex; select an experienced manufacturer such as Guilin Mining Machinery.

Single Vertical Roller Mill: High initial investment yet simple maintenance, low energy consumption and excellent long-term ROI. High equipment integration reduces footprint and cuts investment for workshop and steel structure.

Which Lasts Longer, Raymond Mill or Vertical Roller Mill?

Raymond Mill: Optimized for hardness ≤4. Wear accelerates sharply above Mohs 7. Roller/ring service life only 800~2500 hours.

Vertical Roller Mill: Handles materials up to Mohs 9.5. Reversible roller sleeve service life reaches 6000~12000 hours, better wear resistance than Raymond Mill.

Which Achieves Higher Fineness, Raymond Mill or Vertical Roller Mill?

Raymond Mill: Efficient grinding range 80~400 mesh. Output drops drastically above 400 mesh; 600 mesh achievable with special process.

Vertical Roller Mill: Standard model covers 80~600 mesh, ultra-fine vertical mill reaches 2500 mesh with superior classification precision and tighter particle size distribution.