How to Source a Chinese Alternative to METSO® 500 Powder
Compare sodium metasilicate pentahydrate powder — Na₂SiO₃·5H₂O, CAS 10213-79-3 — with a METSO® 500 Powder target on assay, bulk density method and particle size, then write those lines on the RFQ.
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Short answer
Compare Na₂O and SiO₂, bulk density with the method named — loose, poured or tapped — and particle size as D10, D50 and D90. Passing 30 mesh or 60 mesh is not a D50 and does not prove a mean of 90 µm. On the RFQ, write CAS 10213-79-3, those methods, trial quantity, packing, destination port and the documents for that same powder grade. Ask for the current SDS and a controlled TDS with the quotation.
1. What to compare, and what to write on the RFQ
Compare the incumbent powder and the offered powder on the same three items. Assay is Na₂O and SiO₂. Bulk density needs the method: loose, poured or tapped. Particle size is D10, D50 and D90 from a named instrument. A mesh-passing result is not that distribution.
Write those lines on the RFQ with CAS 10213-79-3, the trial quantity, annual volume, packing, destination port, importer name and the document list for the same powder grade. Ask for the current SDS and a controlled TDS with the quotation.
2. Confirm the Correct Chemical Identity
The substance buyers mean, when they name METSO® 500 Powder, is sodium metasilicate pentahydrate in powder form. Confirm that identity on every document before comparing a physical property or a price.
SDS, TDS, COA and regulatory files must name the same substance and the same grade. A file written for a different hydrate, or for a granular form of the same hydrate, does not describe the powder being sourced.
- Chemical name: Sodium Metasilicate Pentahydrate
- Formula: Na₂SiO₃·5H₂O
- CAS: 10213-79-3
- Physical form: Powder
- Must not be confused with anhydrous sodium metasilicate, CAS 6834-92-0
3. Mesh Data Is Not Mean Particle Size
A sieve result and a mean particle size answer different questions. Passing 30 mesh, or passing 60 mesh, cannot prove a D50 of 90 µm and cannot prove a mean particle size of 90 µm. Fines that pass a coarse sieve can still sit far from the mean a buyer wrote down.
Buyers should request D10, D50 and D90, the particle-size distribution curve, the instrument, the sample preparation and the test method. Comparative testing has to use the same method on the incumbent sample and on the candidate sample. A published mesh-passing line — including a pentahydrate powder result such as passing 30 mesh — remains a sieve result.
4. Why Bulk Density Matters
Bulk density changes the mass delivered by a volumetric dose, a screw feeder and a bag of a given volume. It also changes how the powder blends, how fast it wets and dissolves, how much dust it throws at a charge point, and how much packaging and container volume a tonne occupies.
Always state whether the density is loose, poured or tapped, and name the test method. A reported 850 g/L or 900 g/L cannot automatically be treated as meeting a buyer target written as 700±100 g/L. Those numbers can describe different methods or different grades. The historical 700 g/L figure in the public reference table below is not a Zhongzhi specification.
5. Historical public reference — not a Zhongzhi specification
Na₂O, SiO₂ and loss on ignition tell you which hydrate you are holding. They do not, by themselves, describe how that powder doses, feeds, blends or dissolves. Powder buyers still have to specify bulk density and particle size, each with a method.
The Metso 500 powder column in a historical PQ promotional brochure lists SiO₂ 28.5%, Na₂O 28.7%, LOI at 800°C 43.0%, bulk density 700 g/L and mean particle size 90 µm. The same brochure’s alkalinity table lists a pH of about 12.5 for a 1% sodium metasilicate pentahydrate solution. Those figures are copied below only as historical publicly available reference values—not Zhongzhi product specifications.
Zhongzhi’s published pentahydrate specification is a separate document on the product page. Do not copy a historical 700 g/L or 90 µm target onto that page and treat it as a Zhongzhi specification.
| Property | Historical public reference |
|---|---|
| Na₂O | approximately 28.7% |
| SiO₂ | approximately 28.5% |
| LOI at 800°C | approximately 43.0% |
| Bulk density | approximately 700 g/L |
| Mean particle size | approximately 90 µm |
| pH of 1% solution | approximately 12.5 (pentahydrate row in the same brochure’s alkalinity table) |
PQ historical METSO sodium metasilicate promotional PDF (public file; not a Zhongzhi specification)
6. Request Documents for the Same Grade
Ask for one document set that belongs to the powder grade under review. A granular COA cannot prove a powder grade. Do not stitch the best assay, the best particle-size result and the best density from different grades or different batches and read them as one material.
- Controlled TDS for the powder grade
- Current SDS for the same substance and grade
- A recent COA for that same grade, not a granular lot
- Particle-size report with D10, D50, D90, instrument and method
- Bulk-density result stating loose, poured or tapped, plus the method
- Packaging specification
- Storage conditions and shelf life
7. Verify EU REACH Coverage Before Price Negotiation
Price is the wrong first question if the importer cannot place the substance on the EU market. Confirm coverage with the responsible compliance representative before price is discussed.
Zhongzhi’s published REACH file on this site is for disodium metasilicate, CAS 6834-92-0. It is not proof of coverage for sodium metasilicate pentahydrate, CAS 10213-79-3. An anhydrous registration does not automatically cover the pentahydrate.
- Substance identity on the dossier
- CAS, EC and List identity
- Registrant or Only Representative
- Supply chain the registration actually covers
- Tonnage band
- Named importer coverage
- Whether the coverage is still valid
ECHA guidance: Only Representative
ECHA: enquiry on REACH and CLP
8. Sample Approval Process
Treat sample approval as a sequence. Skipping the method agreement, or approving a sample against a different method from the one on the incumbent file, is how a later production lot fails a comparison the trial appeared to pass.
- 1. Target specification and test method — write the limits and the methods before a sample is shipped.
- 2. Compliance review — substance identity, REACH or Only Representative coverage, and named-importer status, confirmed with the responsible compliance representative.
- 3. TDS and representative COA review — both for the same powder grade.
- 4. Sample testing — against the agreed methods, on a representative sample.
- 5. D50, bulk density and dissolution comparison — same instrument and same density method as the target.
- 6. Pilot batch — one production lot under the agreed specification.
- 7. Consecutive-batch review — more than one lot, so a single COA is not mistaken for ongoing stability.
Request a Specification Review
Send the checklist below with the RFQ. Our team will identify which requirements match a published standard grade, which require factory feasibility review, and which compliance documents must be verified before quotation.
- CAS
- Na₂O / SiO₂
- Bulk density, stating loose, poured or tapped, and the method
- D10 / D50 / D90
- Test method
- Trial quantity
- Annual volume
- Packing
- Destination port
- Importer name
- Required compliance documents
FAQ
Is sodium metasilicate pentahydrate the same as anhydrous sodium metasilicate?
Can passing mesh data be converted directly into D50?
Why does bulk density matter when replacing a powder grade?
Does an anhydrous REACH registration automatically cover pentahydrate?
What documents should be reviewed before sample approval?
Can Zhongzhi Chemical guarantee equivalence to METSO® 500?
Request a Specification Review
Our team will identify which requirements match a published standard grade, which require factory feasibility review, and which compliance documents must be verified before quotation.
- CAS
- Na₂O / SiO₂
- Bulk density (loose, poured or tapped) and method
- D10 / D50 / D90
- Test method
- Trial quantity
- Annual volume
- Packing
- Destination port
- Importer name
- Required compliance documents
METSO® is a registered trademark of PQ Corporation. Zhongzhi Chemical is not affiliated with or endorsed by PQ Corporation. The trademark is referenced solely to describe an incumbent product and buyer sourcing requirements. Figures in the historical public reference table are not Zhongzhi product specifications; confirm them against the buyer’s current approved specification. REACH coverage for sodium metasilicate pentahydrate, CAS 10213-79-3, is a separate confirmation. The published file for disodium metasilicate, CAS 6834-92-0, is not that evidence.