Research on Application Technology of Diatomaceous Earth Filter Aids in Industrial Oil Products

I. Critical Role in Industrial Oil Filtration

Diatomaceous earth (DE) filter aids serve as an indispensable filtration medium in industrial oil refining. Processed from fossilized diatoms through crushing, grading, and calcination, DE exhibits unique properties:

Porosity: 80–93%

Surface area: 15–40 m²/g

Pore distribution: 0.1–20 μm

Widely used in lubricant base oils, transformer oils, hydraulic fluids, and white oils for dewaxing, decolorization, and precision filtration, DE offers three key advantages:

High precision: Removes particles >0.5 μm

Chemical stability: Resists oil additives and acidic compounds

Thermal endurance: Operates continuously at 150°C

ASTM D4929 specifies DE standards for lubricant filtration, validating its industrial use. Practically, DE combines pre-coat and body feed mechanisms (mechanical sieving, depth filtration, and adsorption) for optimal purification.

II. Applications in Lubricant Base Oil Production

Solvent dewaxing:

Forms porous filter cakes with wax crystals

Parameters:

Pre-coat: 5–10 mm (2–3 kg/m²)

Temperature: -15 to -25°C

ΔP: 0.2–0.4 MPa

Performance:

Flow rate: 20–30 L/m²·min

Wax cake oil content: <18%

Hydroprocessed oil filtration:

Removes catalyst fines and gums

Optimized DE gradation (coarse/medium/fine = 3:5:2) reduces mechanical impurities to <10 mg/kg and extends cycles by 30–40%.

Notably, specialty-treated DE minimally adsorbs additives, preserving oil performance.

III. Innovations in Specialty Industrial Oils

Transformer oils:

High-purity DE (<50 ppm metals) reduces tanδ by 30–40%

Three-stage DE filtration (coarse → fine → ultra-fine) with N₂ protection boosts breakdown voltage to >75 kV (IEC 60296 compliant) 

White oil refining:

Industry-standard with activated clay

Dual functions:

Clay particle removal

Trace impurity adsorption

Optimal DE dosage (30–50% of clay weight) achieves:

Flow: 15–25 L/m²·min

UV absorbance (260 nm): <0.05

IV. Advantages in Waste Oil Reclamation

Removes acid sludge/gums, improving yield by 3–5%

High-temperature calcined DE (>900°C) maintains stability at 120–150°C, enhancing color by 2–3 grades.

Economic benefits:

Plate-frame presses reduce cake oil content to <25%

20–30% lower regeneration costs

30% less hazardous waste

Thermal regeneration (600–800°C) restores 70% performance.

V. Process Optimization & Sustainability

Strategies:

Dual-layer pre-coat: 60% coarse (20–30 μm) + 40% fine (5–10 μm) → 20–30% efficiency gain

Dynamic dosing: 0.1–0.3% of oil weight, auto-adjusted by cake resistance (ΔP: 0.3–0.5 MPa)

Temperature control: 80–120°C ideal (15–20% flow increase per 10°C rise)

Equipment selection: Plate frames for high viscosity; leaf filters for low viscosity

Quality standards:

Permeability: 0.5–10 Darcy (viscosity-dependent)

Moisture: ≤0.5%

Acid solubles: ≤3.0%

Heavy metals: API compliant

VI. Trends & Outlook

Technology directions:

Functionalization: Surface-modified DE for selective impurity removal

Smart systems: IoT sensors + predictive maintenance

Green manufacturing: Low-energy processes + spent DE upcycling

Market forecast: 3–4% annual growth, driven by higher oil quality demands and eco-friendly innovations.