China Organic Diatomaceous Earth
China Organic Diatomaceous Earth
Overview
Diatomaceous earth is a naturally occurring sedimentary rock composed of the fossilized frustules of aquatic diatoms. In China, deposits are mined from freshwater lakes where the silica shells have accumulated over millennia, yielding a material that is predominantly amorphous silicon dioxide. Organic certification confirms that no synthetic chemicals or solvents are used during extraction, drying, or milling, preserving the mineral’s intrinsic properties for food‑grade, agricultural, and industrial uses.
Composition and Properties
The product typically contains 88‑94 % SiO₂ (amorphous), with trace amounts of aluminum oxide (≤1.5 %), iron oxide (≤0.5 %), and calcium oxide (≤0.3 %). Particle size distribution is controlled to a D50 of 8‑12 µm and a D97 below 45 µm, providing a high surface area of 45‑55 m²/g. Bulk density ranges from 0.30‑0.45 g/cm³, while true density is approximately 2.2 g/cm³. The material exhibits a pore volume of 1.1‑1.4 cm³/g, giving an oil absorption capacity of 1.8‑2.2 g/g and a moisture content below 6 % after drying.
Manufacturing Process
Raw diatomite is extracted using open‑pit methods that avoid overburden contamination. The ore is crushed to <25 mm, then subjected to a low‑temperature (≤150 °C) rotary dryer to reduce moisture without altering the amorphous silica structure. Subsequent milling employs air‑classified jet mills to achieve the target particle size cut, with inline laser diffraction monitoring. Throughout the line, no chemical fluxes, bleaching agents, or surfactants are introduced, ensuring compliance with organic standards. Final product passes through a magnetic separator to remove ferrous particulates before packaging.
Applications
- Filtration aid for beverage, pharmaceutical, and chemical processes – the high porosity and inert silica matrix provide efficient particle retention while maintaining low pressure drop.
- Absorbent for spill control and industrial cleaning – the material’s oil absorption capacity allows rapid uptake of hydrocarbons and lubricants.
- Carrier for pesticides, fertilizers, and feed additives – the porous structure enables uniform coating and controlled release of active ingredients.
- Soil amendment for horticulture – improved aeration and water retention result from the silica skeleton’s ability to create stable macro‑pores in substrates.
- Non‑chemical pest control – the sharp microscopic edges of diatom fragments damage insect exoskeletons, providing a mechanical barrier when applied as a dust.
Technical Specifications
| Property | Typical Value | Test Method |
|---|---|---|
| SiO₂ (amorphous) | 90 % ±2 % | X‑ray fluorescence (XRF) |
| Moisture content | ≤5 % (w/w) | Gravimetric loss on drying (105 °C, 2 h) |
| Bulk density | 0.35 g/cm³ ±0.05 | ASTM C29 (loose fill) |
| pH (10 % slurry) | 7.5‑8.5 | ISO 4316 |
| D50 particle size | 10 µm ±2 µm | Laser diffraction (ISO 13320) |
| Oil absorption capacity | 2.0 g/g ±0.2 | ASTM D281 |
| Loss on ignition (900 °C) | ≤6 % | Thermogravimetric analysis |
Quality Control
Each batch undergoes a defined control plan: raw material is screened for radioactive nuclides via gamma spectroscopy; after drying, moisture is verified by Karl Fischer titration; particle size distribution is measured every 30 minutes during milling using online laser diffraction; chemical purity is confirmed by XRF for major oxides and ICP‑MS for trace metals (Pb, Cd, As, Hg ≤10 ppm). Microbiological limits (total aerobic count <10³ CFU/g, absence of Salmonella) are tested for food‑grade lots. All test results are recorded in a traceable lot database and made available to customers upon request.
Customization Options
Particle size can be tailored to specific filtration grades (D50 5‑20 µm) by adjusting jet mill pressure and classifier speed. Surface modification with food‑grade silanes is available to increase hydrophobicity for oil‑spray applications. Moisture content can be reduced to <2 % for pneumatic conveying or increased to 8 % for dust suppression where controlled clumping is desired. Packaging formats range from 25 kg multi‑wall paper bags with inner polyethylene liner to 1 tonne flexible intermediate bulk containers (FIBCs) with UV‑stabilized fabric.
Packaging and Shipping
Products are packed in moisture‑barrier bags that maintain relative humidity below 8 % inside the package during transit. Palletized loads use ISO‑standard pallets with stretch‑film wrapping and corner protection to prevent shifting. For bulk shipments, FIBCs are loaded into 20‑foot or 40‑foot containers with dunnage bags to absorb vibration. All containers are marked with handling instructions (“Keep dry, avoid breakage”) and include a material safety data sheet (MSDS) compliant with GHS Rev. 8. Export documentation includes certificate of origin, organic certificate, and test report for the specific lot.
Frequently Asked Questions
Can the particle size distribution be adjusted for a specific filtration rating?
Yes. The jet milling process allows precise control of D50 between 5 µm and 20 µm, with corresponding D97 limits, to meet requirements for plate‑and‑frame, rotary drum, or cartridge filters.
What is the minimum order quantity for a customized grade?
The standard MOQ is 5 tonnes for a custom particle size or surface treatment. Smaller trial quantities (500 kg) can be arranged for feasibility testing, subject to production scheduling.
Which certifications accompany the organic diatomaceous earth?
Each lot is supplied with an organic certificate (NOP or EU equivalent), ISO 9001 quality management certificate, and, upon request, a food‑grade compliance statement (FDA GRAS status for silica).
How are samples arranged for evaluation?
Free 1‑kg samples are available upon request; shipping costs are covered by the requester. Samples are taken from the most recent production lot and include a full test report.
What is the typical lead time after order confirmation?
Standard grades ship within 10‑12 working days. Customized grades require an additional 5‑7 days for process setup and validation.
Contact for Technical Inquiry
To discuss specifications, request a sample, or obtain a formal quotation, please reach out to our technical sales team.