Aluminum hydroxide (ATH) grinding mill operates under special working conditions: heat‑sensitive material, fine abrasive powder, strict low‑temperature requirements, and anti‑iron‑pollution demands. Proper routine maintenance stabilizes product quality (D97, LOI, whiteness), extends equipment service life, reduces unplanned downtime, and avoids ATH thermal decomposition caused by equipment failure. Poor maintenance leads to classifier wheel wear, temperature rise, iron contamination, unstable particle‑size distribution and frequent breakdowns.
1. Daily Routine Inspection (Every Shift)
- Temperature check
Monitor mill body water‑jacket cooling water inlet and outlet temperature. Confirm material temperature stays below 110 °C. Abnormal temperature rise indicates insufficient cooling water flow, scale deposition in cooling jacket, or material accumulation inside grinding chamber. Shut down for inspection if temperature exceeds alarm threshold. - Vibration and noise monitoring
Listen for abnormal noise and observe unit vibration. Excessive vibration may come from loose fasteners, unbalanced rotor, damaged lining or foreign hard impurities entering grinding cavity. - System pressure and negative‑pressure status
Check system negative‑pressure value. Pressure fluctuation suggests filter bag blockage, pipeline blockage or air leakage points. Air ingress brings humid outside air, causing powder caking inside the mill. - Dust leakage check
Inspect sealing parts of feed inlet, discharge port, pipeline flange, access doors. Dust leakage means seal failure, which causes workshop dust pollution and changes internal airflow field. - Oil‑level inspection for bearing assemblies
Check bearing lubrication oil level and oil temperature. Over‑high bearing temperature will transfer heat to grinding zone and risk ATH dehydration.
2. Weekly Maintenance
- Inspect wear‑resistant liners and grinding rotors
For cable‑grade ATH mills with ceramic lining, check liner plates for cracks, chipping or falling‑off. Damaged ceramic parts will introduce iron pollution and reduce product whiteness. Replace or repair liners in time. - Inspect air classifier components
Check classifier wheel blades, guide vanes and secondary‑air channel for wear and powder buildup. Material buildup will distort airflow and cause unstable D97. Clean deposits; check blade wear clearance. - Inspect filter bags of pulse dust collector
Check bag surface for blockage, damage or powder bridging. Damaged filter bags lead to powder loss and coarse material falling back into finished product, causing D97 fluctuation. Check pulse‑jet cleaning function. - Check grounding and static‑elimination connections
Verify grounding cables for mill, classifier, cyclone and pipelines are firmly connected. Loose grounding brings static‑accumulation risk during powder conveying. - Clean material dead zones
Clean residual ATH powder in corners and dead spaces. Long‑term retained material may overheat and decompose, forming hard sintered agglomerates that enter finished products.
3. Monthly Maintenance
- Lubrication maintenance
Replace or replenish bearing lubricant strictly following equipment manual. High‑speed rotor and classifier wheel bearings are key vulnerable parts. Avoid over‑filling or insufficient lubrication, both will trigger bearing overheating. - Check all fasteners and couplings
Tighten loose bolts on mill housing, classifier, motor base. Check belt tension of drive system; slipping belts cause unstable rotor speed and inconsistent D97. - Inspect cooling water circuit
Clean scale and sediment inside water‑jacket and cooling pipelines. Scale buildup reduces cooling efficiency, which is a common cause of over‑temperature in ATH grinding lines. - Inspect sealing gaskets
Replace aging, hardened gaskets on access doors and flanges to prevent air leakage. - Calibrate feeding and control instruments
Calibrate loss‑in‑weight feeder, temperature transmitters and frequency inverters. Deviated instruments lead to unstable feed rate and wrong temperature readings.
4. Quarterly / Semi‑annual Overhaul
- Complete disassembly inspection of grinding rotor and classifier wheel. Measure blade wear thickness. Excessive wear will degrade classification sharpness and cannot be fixed by parameter adjustment.
- Comprehensive inspection of all ceramic‑lined components. Replace severely worn or broken ceramic pieces; any metal exposure will cause iron contamination for high‑purity ATH.
- Inspect fan impeller for wear and imbalance. Clean fan internal powder deposition.
- Check all pneumatic components: solenoid valves, pulse valves, cylinder actuators for aging and failure.
- Conduct full‑system purging before long‑term shutdown, remove all residual ATH powder inside mill and classifier to prevent caking and sintering.
5. Key Maintenance Notes Specific to ATH Mill
- Never ignore cooling‑system maintenance
Unlike ordinary mineral mills, ATH mill cannot run at high temperature. Cooling‑water failure is not only equipment fault, but also quality accident: ATH loses crystal‑water, flame‑retardant performance is permanently damaged. - Avoid metal‑to‑metal contact inside grinding chamber
For cable‑grade ATH, keep ceramic liners intact. Exposed metal surfaces will generate iron impurities, reducing powder whiteness and electrical performance. - Do not perform hot‑repair (welding, cutting) without thorough purging
Before hot work, completely clean ATH powder and organic modifier residues inside equipment to avoid hidden safety risks. Follow lock‑out tag‑out procedure. - Grade‑switch cleaning requirement
When switching between different ATH grades (cable‑grade / artificial‑stone grade), fully purge mill and classifier internals. Residual coarse powder will contaminate fine‑grade products. - Spare‑parts preparation: keep spare ceramic liners, classifier blades, sealing gaskets, filter bags and bearing sets in stock, to shorten downtime during failure.
6. Common Faults Caused by Poor Maintenance
| Fault Phenomenon | Typical Maintenance‑Related Root Cause |
|---|---|
| D97 becomes higher and unstable | Classifier blade wear, material buildup inside classification chamber |
| Product whiteness drops, iron impurity rises | Damaged ceramic lining, metal component exposure |
| Material temperature rises continuously | Cooling‑jacket scaling, insufficient cooling water |
| Frequent system pressure fluctuation | Blocked or damaged filter bags, pipeline powder accumulation |
| Severe mill vibration | Loose bolts, worn rotor liners, unbalanced rotating parts |
ATH grinding mill maintenance focuses on three core dimensions: cooling system reliability, wear‑resistant anti‑pollution components integrity, and stable rotating‑parts condition. Strict daily‑weekly‑monthly inspection cycles can prevent most quality deviations and unexpected shutdowns. Well‑maintained equipment keeps ATH powder within target D97, LOI and whiteness specifications for long‑term continuous production.
