Sodium hydrosulfide (NaHS) 70% flakes is a UN 2949 dangerous good used by copper flotation plants, tanneries and dye makers. Order 70% min flakes in 25 kg PP bags, confirm the COA (NaHS content, sulphide, iron, water), and plan extra lead time because not every shipping line accepts the class.
Sodium hydrosulfide (NaHS, "sodium hydrosulphide" / "硫氢化钠") is a yellow flake chemical with a strong smell, used in large tonnage by copper and molybdenum flotation plants, leather tanneries, dye intermediate producers and the pulp industry. China is one of the biggest suppliers. Buying it from China is very common — but because NaHS is a corrosive dangerous good (UN 2949), the shipping and documentation side needs more planning than an ordinary industrial chemical.
1. What is NaHS used for?
- Copper / molybdenum flotation — as a depressant to separate molybdenum from copper concentrates
- Leather depilation — the lime–NaHS unhairing step in tanneries
- Dyestuff intermediates — raw material for sulfur dyes and organic intermediates
- Pulp and water treatment — caustic substitute in kraft pulping, and heavy-metal precipitation
If you buy for a flotation plant or a tannery, the grade you need is almost always NaHS 70% min, yellow flakes.
2. Grades and what the COA should show
NaHS is normally sold as solid flakes (70% min) or as a 32% aqueous solution. For ocean freight, flakes are the standard export form. Check these values on the Certificate of Analysis:
| Parameter | Typical value | What to check |
|---|---|---|
| NaHS content | 70% min | Below 68% means short supply |
| Na2S content | balance | Free alkali affects use |
| Appearance | Yellow flakes | Dark / black = oxidation damage |
| Moisture | ≤ 2% | High moisture cakes in bags |
3. HS code and dangerous-goods classification
Sodium hydrosulfide flakes fall under HS 2830.90 (sulfides, n.e.s.). For shipping it is classified as:
- UN 2949 — Sodium hydrosulfide, hydrated
- Class 8 (corrosive), Packing Group II
- Proper shipping name: "SODIUM HYDROSULPHIDE, HYDRATED with not less than 25% water of crystallization"
This matters: a standard dry container cannot carry NaHS without the supplier arranging dangerous-goods booking (DG cargo, IMDG-compliant), UN-certified packaging, a maritime declaration and a proper MSDS. Buyers should confirm their own port or customs can accept Class 8 imports and whether an import permit is needed.
4. Packaging and MOQ
- 25 kg / 50 kg PP bags with inner liner — the standard for trial and mid-size orders
- 900–1000 kg super sacks for flotation plants and tanneries buying by the container
A 20ft container takes roughly 20–23 tons in super sacks. Because NaHS is hygroscopic and reacts with acids, bags must be dry, sealed and kept away from moisture and acid cargo in the same container. A first trial order of 1–2 tons is workable but at a higher per-ton price than full-container loads.
5. Shipping time to your port
- West Africa (Lagos, Tema, Abidjan, Dakar): about 25–40 days
- East Africa (Mombasa, Dar es Salaam): about 20–35 days
- South America (Callao, Santos, Cartagena): about 35–50 days
DG cargo sometimes takes a few extra days for booking because not every sailing accepts Class 8 — plan 1–2 weeks of buffer over a normal chemical shipment.
6. The three most common problems
(1) Oxidation and darkening — NaHS turns dark when exposed to air or moisture; demand sealed, lined bags and recent batch photos. (2) Short purity — confirm NaHS 70% min on the COA before loading, not after arrival. (3) DG paperwork delays — a supplier without dangerous-goods export experience will stall at the port; always confirm the exporter has handled UN 2949 before.
SAIFENG supplies sodium hydrosulphide 70% min flakes in 25kg bags and super sacks, together with caustic soda, sulfur, urea and mining chemicals, to flotation plants and tanneries across Africa and South America. Every inquiry is answered within 2 working hours, and we prepare the full DG documentation for each shipment.
View sodium hydrosulphide & industrial chemicals Get a quote for your port