Oxalic acid dihydrate 99.6% is a UN 3261 (Class 8) dangerous good used in rare-earth extraction, metal cleaning, textile bleaching and leather tanning. Order 99.6% min in 25 kg PP bags, check the COA for purity, sulphate and iron, and confirm your shipping line accepts Class 8 before booking.
Oxalic acid (H2C2O4·2H2O, "乙二酸 / 草酸") is a white crystalline solid used in wide range of industries: it is the standard precipitant in rare-earth extraction, a strong rust and scale remover in metal cleaning, a depilatory agent in leather tanning, and a bleaching agent in textile and marble polishing. China is the world's main producer and exporter, so buying oxalic acid from China is straightforward — but it is a corrosive solid and needs a little more care than ordinary bulk chemicals.
1. Which grade do you need?
Most export-grade oxalic acid is sold as dihydrate crystals, 99.6% min. Tell your supplier your end use:
- Industrial grade 99.6% min — standard for metal cleaning, rust removal and marble polishing
- Rare-earth / reagent grade — stricter heavy-metal and sulfate limits, required by rare-earth refineries for product purity
- Leather and textile grade — controlled ash and chloride for tanneries and bleaching
Most buyers outside China order the standard 99.6% dihydrate crystals; rare-earth plants in particular should ask for the full heavy-metal table on the COA.
2. What the COA should show
Always check the Certificate of Analysis before shipment. These four numbers matter most:
| Parameter | Typical value | What to check |
|---|---|---|
| Oxalic acid content | 99.6% min | Below 99% means short on active acid |
| Sulfate (SO4) | ≤ 0.2% | High sulfate ruins rare-earth product quality |
| Heavy metals (as Pb) | ≤ 0.001% | Required for food-contact and rare-earth use |
| Residue on ignition | ≤ 0.08% | High ash = impure batch |
3. HS code and shipping classification
Oxalic acid is classified under HS 2917.11 (oxalic acid and its salts). For ocean freight it is:
- UN 3261 — Corrosive solid, acidic organic, n.o.s.
- Class 8 (corrosive), Packing Group III
In practice oxalic acid moves easily: most container lines accept Class 8 organic solids, but the supplier still needs to book it as DG cargo with UN-certified bags, an MSDS and a dangerous-goods declaration. It must be stowed away from alkalis (such as caustic soda) and food cargo in the same hold.
4. Packaging and MOQ
- 25 kg woven PP bags with inner polyethylene liner — the standard for trial and mid-size orders
- Super sacks (1000 kg) for metal-treatment plants and rare-earth refineries
A 20ft container holds roughly 25 tons in 25kg bags. Because oxalic acid is hygroscopic, sealed bags and a dry container are essential; damp oxalic acid cakes and loses quality.
5. Shipping time to your port
- West Africa (Lagos, Tema, Abidjan, Dakar): about 25–35 days
- East Africa (Mombasa, Dar es Salaam): about 20–30 days
- South America (Santos, Cartagena, Callao): about 35–45 days
6. The three most common problems
(1) Caking from moisture — bags absorb water and harden; insist on lined, dry bags and a clean container. (2) High sulfate for rare-earth use — if you extract rare earths, always check the sulfate value on the COA, not just total purity. (3) Mis-declared as general cargo — a supplier without DG experience can cause port detention; confirm the exporter has shipped UN 3261 before.
SAIFENG supplies oxalic acid 99.6% dihydrate in 25kg bags and super sacks, together with caustic soda, sodium hydrosulfide, urea and mining chemicals, to metal-treatment plants, tanneries and rare-earth buyers across Africa and South America. Every inquiry is answered within 2 working hours.
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