Aluminum hydroxide (ATH) is classified as low‑hazard inorganic mineral filler. However, fine ATH powder generates large amounts of dust during grinding, classification, modification, packaging and material transfer operations. Improper handling may cause respiratory irritation, dust accumulation risks, equipment wear, and secondary quality risks. Though ATH is non‑combustible itself, good safety management is still required across the whole processing line.
1. Dust Inhalation & Personal Protection
Fine ATH dust can irritate nasal passages, throat and respiratory tract with long‑term repeated inhalation. It is not classified as pneumoconiosis‑causing hazardous mineral, but chronic exposure shall be avoided.
- Wear appropriate PPE: dust‑proof respirators, safety goggles, anti‑dust work clothes when entering production zones.
- Avoid eating, drinking or smoking in powder‑handling areas; wash hands and face thoroughly after operation.
- Prevent skin contact with large‑volume fine powder; prolonged contact may cause mild skin dryness. In case of eye contact, flush eyes with plenty of clean water.
2. Dust Explosion Risk Assessment
ATH powder itself is non‑flammable and non‑explosive. However, accumulated dust layers in the plant may mix with other combustible impurities (coupling‑agent vapors, organic modifier residues, rubber/plastic debris). Hybrid dust‑vapor mixtures can create explosion hazards.
- Maintain negative‑pressure closed system for grinding‑classification‑modification sections; minimize open dust emission points.
- Regularly clean dust deposits on beams, equipment tops and floor gaps; avoid thick dust layer accumulation.
- For dry surface‑modification units using silane or fatty‑acid modifiers: control modifier vapor concentration, equip inert gas protection and explosion‑venting panels for processing vessels.
- Prevent high‑energy ignition sources: eliminate open flames, avoid ungrounded static electricity, restrict spark‑producing tools inside dust zones.
3. Static Electricity Prevention
Fine flowing ATH powder generates static charge during pneumatic conveying.
- All processing equipment: mills, classifiers, cyclones, bag‑house collectors, conveying pipelines must be reliably grounded.
- Use conductive hoses and conductive fabric filter bags for powder collection.
- Avoid high‑velocity uncontrolled powder free‑fall, which amplifies static build‑up.
4. Thermal Safety: Prevent ATH Decomposition & Over‑heating
ATH decomposes and releases crystal water above 150 °C. Even though decomposition is non‑violent, hot dehydrated alumina powder may cause thermal burns, and decomposed material becomes waste product.
- Monitor equipment temperature; keep material temperature consistently below 110 °C via water‑jacket cooling.
- Prevent material stagnation and coking inside dead corners of dryers, mills and classifiers. Trapped residual ATH may gradually over‑decompose.
- Do not perform hot‑work welding or cutting on powder‑filled pipelines without full purging and cleaning.
5. Equipment Operation Safety
- Maintain proper sealing for all negative‑pressure processing lines to stop powder leakage into workshop environment.
- Carry out lock‑out tag‑out procedures before opening mill, classifier or modification chamber for inspection and maintenance. Rotor and impeller parts still coast for a long time after motor shutdown.
- For high‑shear modification units, never open access doors while equipment is running.
- Regularly inspect ceramic liners and wear‑parts; broken liner fragments may damage downstream equipment.
6. Storage & Packaging Safety
- Store bagged ATH powder in dry, well‑ventilated warehouse. Keep bags sealed to prevent moisture absorption and caking.
- Stack bags properly, avoid over‑height stacking which causes bag rupture and dust spillage.
- Keep ATH separated from strong acids. ATH reacts with strong acid to produce salt solution. Spilled powder should be swept instead of compressed‑air blowing (blowing re‑suspends fine dust into air).
7. Waste & Spill Handling
- Spilled ATH powder: collect by sweeping or vacuum dust extractor (explosion‑proof type). Do not blow with compressed air.
- Waste ATH powder is mostly inert solid waste; comply with local solid‑waste disposal regulations.
ATH powder itself is low‑toxic and non‑combustible. The main hazards come from fine dust inhalation, hybrid combustible dust‑modifier‑vapor risk, static electricity and thermal decomposition. Key measures include closed negative‑pressure production configuration, proper personal protective equipment, static grounding, regular dust cleaning, strict temperature control and standardized maintenance procedures.
