Light soda ash is the grade selected in fertilizer and agro-industrial plants where sodium carbonate is dissolved rather than conveyed — batch make-up of alkali solutions for pH control, scrubbing and effluent neutralisation. Its fine particle size gives rapid dissolution, which shortens make-up cycles and reduces undissolved carry-over into dosing lines. As with the dense grade, its role here is as a plant reagent; sodium carbonate is not a nutrient input and is not applied to land.
Substance identity
| Field | Value |
|---|---|
| Chemical name | Sodium carbonate (anhydrous), light grade |
| Formula | Na2CO3 |
| CAS number | 497-19-8 |
| PubChem CID | 10340 |
| Molar mass | 105.99 g/mol |
| EC number | 207-838-8 |
| Role in this category | Process reagent — not a fertilizer nutrient product |
Specification
Typical commercial ranges, not guaranteed limits.
| Parameter | Typical range | Relevance in this application |
|---|---|---|
| Total alkali as Na2CO3 | 99.2 % min, dry basis | alkali equivalent per tonne |
| Bulk density | approx. 0.50–0.60 t/m3 | storage volume; silo design must suit a cohesive powder |
| Particle size | predominantly below approx. 0.15–0.2 mm | governs dissolution rate |
| Water-insoluble matter | typically ≤ 0.03–0.10 % | residue in make-up tanks, strainer and nozzle fouling |
| Sodium chloride (NaCl) | typically ≤ 0.3–0.8 % | chloride carried into the treated stream |
| Loss on heating | typically ≤ 0.5–1.0 % |
For solution-make-up duty, water-insoluble matter is the trace to watch — it accumulates in tank bottoms and blocks strainers — more than the iron limit that governs glass grade.
Properties
Melting point approx. 851 °C; true density approx. 2.53–2.54 g/cm3; solubility approx. 21.5 g/100 g water at 20 °C, maximum near 35 °C, slight decline thereafter; 1 % solution pH approx. 11.3–11.6; dissolution exothermic; hygroscopic and cake-prone.
Two design consequences. First, because solubility passes through a maximum near 35 °C, a solution made up near saturation at warm ambient can deposit solids in dosing lines both on cooling and, on the other side of the maximum, on heating — do not run concentrated make-up close to saturation without trace heating and a defined operating band. Second, dissolution releases heat; on large batches, control the addition rate and keep agitation running throughout.
Applications
- Batch make-up of carbonate alkali solutions for pH control across wet-process operations.
- Acid-gas scrubbing solutions on plant vents and stacks.
- Effluent neutralisation ahead of discharge or metals precipitation.
- pH adjustment in precipitation, crystallisation and purification steps, where carbonate buffering is preferred to the sharper response of caustic soda.
- On-site feedstock for other sodium salts.
Handling and storage
Alkaline and notably dusty; eye protection, gloves and respiratory protection appropriate to the dust level; enclose transfer points and extract at source; safety data sheet governs.
Hygroscopic and strongly cake-prone — store sealed, dry, off the floor, away from condensation. Expect bridging and rat-holing; silo and feeder design must suit a cohesive, aeratable fine powder, and dense-grade geometry should not be reused without review.
Incompatibilities: acids — vigorous CO2 evolution and heat, a live concern in plants storing sulphuric, phosphoric or nitric acid; segregate storage and spill bunds. Aluminium and zinc in moist conditions (alkaline attack, hydrogen evolution). Galvanised surfaces. Do not co-store with acidic fertilizer intermediates or acidic wash liquors.
Notes
- Not a soil input. Sodium carbonate adds sodium and carbonate alkalinity; sodium disperses clay and degrades soil structure, infiltration and permeability. Irrigation-water assessment treats carbonate alkalinity with sodium as a hazard through the residual sodium carbonate (RSC) index. For soil pH correction, the conventional materials are ground limestone and dolomitic limestone.
- Light versus dense is a handling decision, not a chemical one. Choose light where the reagent is dissolved; choose dense where it is stored in silos and dosed mechanically.
- Duplication note: this page describes the same product as
/chemical-products/soda-ash-light.html. Under the accepted plan this URL is a 301, not a page.
Sources: general chemical knowledge and public reference data only (PubChem identifiers as supplied and cross-checked against general knowledge, ECHA-style substance identity conventions, standard inorganic-chemistry reference values). **