In open-circuit operation, material passes through the mill once and the discharge is the final product - simple to operate but typically produces a wider particle-size distribution with some over-ground and under-ground material. In closed-circuit operation, mill discharge is fed to a classifier (hydrocyclone or spiral classifier); correctly-sized material proceeds to the next process step while oversize material is returned to the mill for further grinding. Closed-circuit operation produces a tighter, more controlled particle-size distribution and is the standard configuration for flotation feed preparation, though it requires the additional classifier equipment and associated pumping.

Ball load (shown in the specification table) is the total mass of steel grinding balls in the mill at normal operating fill level - typically 30–35% of internal mill volume. Balls wear at a rate dependent on feed abrasiveness, ball hardness, and mill operating parameters; typical wear rates range from 0.5–1.5 kg of steel consumed per tonne of ore processed for moderate-abrasion materials. Mills are topped up with new balls on a regular schedule (often weekly or monthly depending on throughput) to maintain the target ball charge mass and size distribution, since larger balls wear down into smaller sizes that contribute to the overall grinding action until they are eventually discharged or screened out.

Model selection depends on required throughput (t/h), target output particle size, feed hardness (work index), and feed top size after primary crushing (typically ≤25 mm for this series). As a starting point, match required throughput to the capacity range in the specification table at the target output size band (0.074–0.4 mm for most models, 0.075–0.89 mm for the smaller φ900 models). Note that the stated capacity ranges assume moderate-hardness ores; for harder feed materials (higher Bond work index), select one size larger, or provide your ore's work index and required P80 grind size for a confirmed recommendation based on grinding-circuit calculations.

Frame selection depends on three factors: required daily capacity (t/d), maximum feed lump size, and material hardness/abrasiveness. As a starting point, match your required capacity to the t/d range in the specification table - but note that capacity is also affected by material hardness (the t/d figures are typically based on materials with a Mohs hardness below 6 such as limestone and gypsum) and target fineness (finer target particle sizes reduce throughput within a given frame). For harder materials (Mohs 6–7, such as quartz or barite) or very fine target particle sizes, select one frame size larger than the capacity table would suggest, or consult us with your feed data for a confirmed recommendation.

Yes, within the 0.044–0.125 mm (125–325 mesh) range, finished particle size is primarily controlled by the analyzer (classifier) motor speed. Increasing classifier speed returns more material to the grinding zone for further reduction, producing a finer finished product; decreasing classifier speed allows coarser material to pass, increasing throughput at a coarser particle size. For target particle sizes outside this range, consult us regarding alternative roller and ring geometry.

Both configurations share the same mill housing, main shaft, and classifier. A 4-roller configuration adds one additional grinding roller and ring set around the main shaft, increasing the grinding surface area in contact with the material at any instant. This raises throughput by approximately 25–30% within the same frame footprint at a modest increase in main-motor power draw. The 3-roller configuration is suitable where the lower end of the capacity range is sufficient; the 4-roller configuration is selected when maximum throughput from a given frame size is required.

Mesh aperture is selected based on the smallest particle size that must be retained on the deck for dewatering - particles smaller than the aperture pass through with the drainage water and are not dewatered by that deck. For washed coarse sand and aggregate (typically retaining everything above 0.15–0.3 mm), apertures of 0.5–1 mm are common. For fine-sand or tailings dewatering where the target product is finer, apertures down to 0.25 mm are used. Coarser apertures (10–50 mm) are used for de-watering and de-sliming larger washed aggregate fractions. We confirm the recommended mesh based on your feed gradation curve at quotation stage.

A steep angle (25–30°) maximises the gravity component acting to drain free water from the slurry layer as soon as it lands on the deck. This rapid initial drainage is the single largest contributor to overall dewatering performance - most free water separates within the first portion of the deck length. The remaining deck length, combined with the 960 rpm vibration, then focuses on removing the more difficult capillary-held moisture from the particle surfaces. A horizontal screen at the same vibration frequency would require significantly more deck length to achieve the same discharge moisture.