In cement manufacturing, raw material grinding is one of the most energy-intensive processes across the whole production line. Cement plants running outdated ball mill circuits face growing pressure to cut power consumption while boosting operational flexibility. This case study covers a full grinding system replacement project at a Southeast Asian cement plant. It walks through every critical stage, from initial technical feasibility assessment, equipment selection, site construction, performance testing to final project handover and acceptance.
Project Background & Business Drivers
A major Southeast Asian cement manufacturer operates multiple production lines with total clinker capacity above 13 million tons per year.
At one of its production sites, Line 1 relied on two conventional ball mill circuits for raw meal preparation. These grinding lines had been in continuous service for many years.
The plant identified clear, quantifiable reasons to carry out this grinding system retrofit:
- Rising electricity expenses. The existing ball mill circuit consumed 21.7 kWh per ton for raw meal grinding. With regional power prices climbing steadily, this high energy cost was no longer economically viable.
- Production capacity bottlenecks. The old grinding system struggled to deliver consistent raw meal output to feed its 4,500 tpd clinker production line.
- Limited operational flexibility. The ball mill layout restricted the plant’s ability to adapt to fluctuating raw material properties and changing product fineness requirements.
- Growing market competition. Neighboring cement factories had upgraded to higher-efficiency grinding technology. Keeping the original ball mill setup was not a sustainable long-term plan.
Site management set clear revamp targets: replace the legacy grinding circuit with a modern high-efficiency grinding system. The goal was to slash specific power consumption while maintaining or raising throughput.
The business case was supported by projected annual electricity savings of EUR 1.5 million, delivering an attractive return on investment.
## Technical Evaluation & Solution Selection
### Comparison of Mainstream Grinding Technology Options
The project team performed a thorough technical review of available grinding technologies. Two primary solutions were evaluated:
1. Vertical roller mill system
A vertical roller mill combines drying, grinding, classification and material conveying in one compact unit. However, hitting the target throughput requires a large main fan, and continuous water injection is often needed to stabilize the grinding bed. Energy tests confirmed that under identical working conditions, a vertical roller mill consumes an extra 3–4 kWh per ton compared with the alternative roller press circuit.
2. Roller press finish grinding system
Roller press technology uses high inter-particle compression with short material dwell time. It delivers the strongest energy-saving potential for finish grinding applications. Compact footprint and advanced classifier design make roller press finish grinding a competitive substitute for vertical mills, especially for cement raw meal processing.
### Selected Grinding Circuit Solution
After rigorous comparison, the plant chose a COMFLEX grinding circuit built around a roller press, forming a closed-loop system with static and dynamic classifiers.
Key equipment specifications:
- Roller press model: RPM18-200/180; roller diameter 1,800 mm, roller width 2,000 mm. Two 1,850 kW motors provide total installed power of 3,700 kW.
- Two-stage static classification system: 6,000 mm × 2,000 mm coarse static classifier for feed dispersion and pre-classification; 8,600 mm diameter fine static classifier to control product fineness.
- Product collection: four cyclones, 3,800 mm diameter each.
- System fan power: 1,500 kW.
- Bucket elevator: total height 45.1 m, drive power 400 kW.
This two-stage static classifier layout is designed to cut classification energy demand and reduce power draw for the main system fan.
Fresh raw feed enters the coarse static classifier for material dispersion, drying and pre-classification. Oversized coarse particles flow to the roller press for compression grinding. Fine particles travel with gas flow into the fine static classifier for secondary separation, before being collected as finished raw meal product via cyclones.
## Key Project Implementation Phases
### Phase 1: Site Survey & Basic Engineering Design
The engineering team completed a three-week detailed site survey.
Work scope included checking load capacity of the existing ball mill foundation, verifying workshop height and crane lifting capacity, confirming power supply and switchgear modification requirements, mapping duct routing space, and drafting a temporary production plan during construction.
During basic engineering, 136 construction drawings were created, covering civil modification, equipment foundations, steel structures, piping layout, electrical and automation control. All design documents were submitted to the owner’s engineering team for review and approval.
### Phase 2: Old Equipment Demolition & Civil Works Modification
Dismantling of the legacy grinding system followed a predefined work sequence and took 42 days.
Demolition scope: two ball mills, drive assemblies, feeding and discharge equipment, original classifiers and all gas duct piping.
Civil modification ran in parallel: partial demolition and reinforcement of old foundations, pouring of new equipment foundations (roughly 680 m³ concrete), temporary widening of installation access routes, plus upgrades to control room and electrical substation.
### Phase 3: Equipment Installation & Piping Hook-Up
After equipment delivery, installation followed this sequence:
1. Roller press main frame and roller assembly installation, with levelness tolerance controlled within 0.05 mm per meter.
2. On-site assembly and welding for the two static classifiers.
3. Cyclone installation and dust duct fitting.
4. Erection of the 45.1 m bucket elevator.
5. System fan and ductwork installation.
6. Electrical wiring and control system commissioning.
At peak construction, 87 workers were on site, including a 6-person Chinese installation supervision team and 81 local subcontract workers.
### Phase 4: Individual Equipment Commissioning & Full System Trial Run
Each standalone machine first underwent no-load testing to verify rotation direction, temperature rise, vibration and other operating parameters. After individual checks passed, the team moved to integrated system trial runs with staged load-up:
- 4 hours full-system no-load test
- 8 hours at 20% load
- 24 hours at 50% load
- 48 hours at 75% load
- Final continuous 72-hour operation at 100% full load
### Phase 5: Performance Test & Final Acceptance
Performance testing started after stable full-load operation for 72 hours. Contractual guarantees vs actual results:
- System throughput: Contract ≥305 t/h; Actual 312 t/h – Pass
- Specific power consumption: Contract ≤16.5 kWh/t; Actual 15.8 kWh/t – Pass
- Product fineness (R0.08 mm sieve residue): Contract ≤12%; Actual 10.5% – Pass
- Product moisture: Contract ≤0.5%; Actual 0.4% – Pass
- Equipment availability during test: Contract ≥98%; Actual 99.2% – Pass
The full performance test ran continuously for 7 days. All KPIs met or exceeded contractual requirements, and the project obtained final acceptance.
## Retrofit Outcomes & Key Lessons Learned
### Measurable Project Results
- Throughput: Original ball mill capacity 215 t/h → upgraded roller press circuit 312 t/h, **45% capacity increase**.
- Specific power consumption: 21.7 kWh/t reduced to 15.8 kWh/t, **27.2% energy cut**.
Based on these improvements, annual electricity savings reach approximately EUR 1.5 million.
### Key Lessons
1. Comprehensive pre-project technical assessment directly determines project success. This project benefited from six months of continuous raw material sampling and lab testing, ensuring roller press sizing matched real plant operating conditions.
2. Temporary production contingency plans must be aligned with plant production teams at an early stage. While removing old equipment, this site minimized production losses by rerouting capacity from other production lines and moderate external clinker procurement.
3. Training for local subcontract crews should start in advance. Before equipment shipment, local installation technicians received two weeks of hands-on training, shortening on-site construction time significantly.
4. Performance test metrics need to balance practical measurability and fairness. All test instruments were third-party calibrated to guarantee reliable, auditable data.
5. Pre-ordering critical wear spares is critical for stable long-term operation. By project acceptance, both parties confirmed the first-year wear parts list and delivered initial spare stock, avoiding unplanned downtime from long procurement lead times.
## Conclusion
From technical assessment to handover acceptance, the whole project was completed within 4 months.
The new raw meal grinding system brought the plant’s grinding power consumption down to the lowest level across the region, delivering around EUR 1.5 million in yearly power savings.
Beyond energy savings, the stable and adjustable roller press circuit helps the plant handle raw material variations and product mix changes, creating room for further capacity expansion.
This retrofit delivers a proven reference for cement producers considering ball mill replacement or grinding circuit optimization. It provides actionable implementation workflows and risk control guidelines for similar mineral processing and cement grinding upgrades.
If you are exploring grinding system upgrades for cement or mineral processing operations, reach out to our engineering team for a customized feasibility study and preliminary solution proposal for your site conditions.