| HS Code | 277538 |
| Product Name | Aditya Birla Grasim Caustic Soda Flakes |
| Chemical Formula | NaOH |
| Molecular Weight | 40.00 g/mol |
| Cas Number | 1310-73-2 |
| Appearance | White flakes |
| Purity | 98% min |
| Bulk Density | 1.0 g/cm³ |
| Melting Point | 318°C |
| Boiling Point | 1388°C |
| Solubility In Water | 1090 g/L at 20°C |
| Specific Gravity | 2.13 |
| Ph 1 Solution | 13 |
| Hygroscopic Nature | Highly hygroscopic |
As an accredited Aditya Birla Grasim Caustic Soda Flakes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Available in 25 kg strong HDPE bags with moisture-proof inner lining, ensuring safe handling, storage, and product purity. |
| Container Loading (20′ FCL) | 20′ FCL container loaded with Aditya Birla Grasim Caustic Soda Flakes, properly packed, secured, and ventilated for safe transport. |
| Shipping | Aditya Birla Grasim Caustic Soda Flakes ship in sealed HDPE bags with moisture-proof liners, placed in clean, dry containers. As a corrosive, deliquescent material, they require protection from humidity and acids, proper hazardous-goods labeling, and safe handling with PPE to prevent damage and ensure regulatory compliance during transit. |
| Storage | Store Aditya Birla Grasim Caustic Soda Flakes in a cool, dry, well-ventilated area in tightly sealed, corrosion-resistant containers. Keep away from moisture, water, acids, and incompatible chemicals. Use pallets to avoid floor contact. Ensure containers are clearly labeled. Do not store near food or animal feed. |
| Shelf Life | Shelf life is indefinite if stored in airtight, dry conditions away from moisture and humidity. |
Aditya Birla Grasim caustic soda flakes are introduced into barren liquor make-up tanks in continuous Bayer digestion circuits processing boehmitic or diasporic bauxite, where the Na₂O-to-Al₂O₃ molar ratio is corrected before re-injection into tube digesters operating at 240–280 °C and 30–50 bar gauge. The flake is wet-blended with spent liquor at 60–80 °C in agitated make-down tanks, and the resulting liquor is passed through sand traps and Kelly filters to remove undissolved particles; typical barren liquor is maintained at 140–260 g/L Na₂O caustic with a molar ratio of 1.45–1.70 Na₂O to Al₂O₃. Reactive silica in bauxite consumes caustic through desilication product formation, and the loss is treated as a variable in refinery mass balance rather than as a fixed stoichiometric coefficient because kaolinite and quartz behave differently under digestion conditions. Incoming caustic soda flakes are tested to ASTM E291-18 for total alkalinity, carbonate, and chloride before make-up; smelter-grade alumina produced in the refinery is characterized for loss on ignition according to ISO 806:2004. Terminal product is smelter-grade alumina for Hall-Héroult reduction cells. An operational boundary is the avoidance of direct injection of flake into high-silica pregnant liquor without aging, as this can induce premature desilication product precipitation and scale accumulation on heat exchanger surfaces.
White liquor used in kraft pulping is a multicomponent electrolyte containing NaOH and Na₂S, and caustic soda flake is dissolved in weak wash or low-temperature white liquor to raise effective alkali when the causticizing loop cannot meet digester demand. In softwood batch digesters, effective alkali is typically controlled at 14–20% Na₂O on oven-dry wood, with sulfidity maintained at 25–35%; flake addition is calculated from the mill’s white liquor total titratable alkali and active alkali values rather than as a fixed percentage. The dissolution step is performed in agitated make-down tanks with dilution water at 30–50 °C, and the fortified liquor is returned to the digester circulation line before injection. Mill laboratories quantify hydroxide, carbonate, and sulfide in white and green liquors by titration methods aligned with TAPPI T 624 cm-21; cooked pulp kappa number is monitored using ISO 302:2015 to confirm delignification. Terminal product types include bleached softwood and hardwood kraft pulp for packaging, tissue, and printing grades. Process limitations arise when carbonate accumulates in the white liquor system above 0.2 mol/L because causticizing efficiency drops and flake caustic cannot substitute for the lost sulfide without shifting sulfidity outside target.
During chain mercerization of cotton yarn, sodium hydroxide flake is used to replenish alkali removed by fabric carry-over and neutralization, maintaining the saturator bath at 19–23% NaOH by weight, corresponding to 200–240 g/L NaOH. The flake is dissolved in soft water and fed into the recirculation loop of the mercerizing unit; bath temperature is controlled at 15–20 °C because higher temperatures reduce fibre swelling and luster development. Fabric dwell time in the caustic saturator is typically 30–60 s under controlled warp and weft tension, followed by a stabilization wash at 50–60 °C to prevent slack-mercerization shrinkage. Mercerized cotton yarn or fabric intended for dyed goods is evaluated for colourfastness to domestic and commercial laundering according to ISO 105-C06:2010; incoming caustic soda flake is checked for carbonate and chloride using ASTM E291-18 because carbonate concentrations above 2% of bath weight can cause surface dulling and uneven dye uptake. Terminal product types include high-luster cotton yarn, woven shirting, and knitwear. An operational boundary is the intolerance of the mercerizing bath to polyvalent metal ions; iron above 10 mg/L can create localized staining, so dissolution tanks and distribution lines are specified in stainless steel or lined carbon steel. Published production-scale data for carbonate tolerance in high-speed chain mercerizers is limited; mills commonly maintain carbonate below 2% as an operational limit.
In high-shear neutralisation loops producing linear alkylbenzene sulfonate pastes, caustic soda flake is dissolved to 20–30% NaOH by weight in a dedicated make-down vessel and dosed into a stoichiometric reaction with linear alkylbenzene sulfonic acid. The neutralisation is performed at 40–60 °C with a recirculating loop reactor; the free alkalinity of the finished paste is controlled at 0.05–0.10% NaOH, corresponding to a product pH of 7.5–9.0 measured at 1% aqueous dilution. Anionic active matter in the terminal LAS paste or liquid detergent is determined according to ISO 2271:1989, and the use of flake caustic rather than 50% NaOH membrane-cell solution requires monitoring of carbonate and chloride to avoid haze formation in clear detergent formulations. The downstream production process includes pH correction of the neutralised paste, addition of hydrotropes or nonionic surfactants, and final adjustment of active matter to 15–30% for domestic liquid detergents. Terminal product types include heavy-duty laundry liquids, dishwashing liquids, and spray-dried washing powders. A processing constraint is that localized overdosing from dry flake addition can generate sodium carbonate scale on loop reactor walls; therefore flake is always predissolved and filtered through a 100 µm strainer before entering the dosing pump.
Transesterification of low-free-fatty-acid glyceride feedstocks with methanol and flake sodium hydroxide proceeds through in situ formation of sodium methoxide, and the dissolution of flake in methanol is performed in a sealed methoxide make-up vessel at 25–40 °C with dry methanol containing less than 0.1% water. Catalyst charge is set at 0.3–0.5% NaOH by mass of oil when the feedstock free fatty acid content is below 0.5% as oleic acid; every 0.1% FFA consumes approximately 0.14 g NaOH per kg oil through soap formation and must be included in the total alkali addition. The oil is dried to below 0.1% moisture and preheated to 55–65 °C before the methoxide enters the transesterification reactor, where residence time is typically 60–120 min under high-shear agitation. After phase separation, the upper FAME phase is washed with acidulated water, and the lower glycerin phase containing sodium soaps is withdrawn.
| Parameter | ASTM D6751-23a limit | EN 14214:2012+A2:2019 limit |
|---|---|---|
| Free glycerin | ≤ 0.020 wt% | ≤ 0.02% |
| Total glycerin | ≤ 0.240 wt% | ≤ 0.25% |
| Na + K combined | ≤ 5 mg/kg | ≤ 5 mg/kg |
| Water | ≤ 0.050 vol% | ≤ 500 mg/kg |
| Ester content | Not specified | ≥ 96.5% |
Compliance of the terminal fatty acid methyl ester product is tested according to ASTM D6751-23a for free glycerin ≤ 0.020% and total glycerin ≤ 0.240%, and EN 14214:2012+A2:2019 for ester content ≥ 96.5%, Na+K ≤ 5 mg/kg, and water ≤ 500 mg/kg. Terminal product type is B100 biodiesel for blending with petroleum diesel. The dominant process limitation is aqueous soap-stock formation at the methoxide preparation stage; if the flake is added to methanol too rapidly, the exotherm exceeds 60 °C and causes localized methanol boiling, loss of methoxide homogeneity, and unreacted flake carryover into the oil phase, increasing emulsion stability during separation.
Low-alkalinity surface water entering a municipal or industrial treatment plant can be pH-corrected by metering a concentrated sodium hydroxide solution prepared from caustic soda flake in a dedicated make-down system. The flake is dissolved to 25% or 50% NaOH using softened or demineralized dilution water, and the exothermic dissolution temperature is maintained below 70 °C by circulating the make-down tank through a heat exchanger. Dosing pumps inject the caustic solution into the raw water line upstream of a static mixer and pH analyzer; the required amount is alkalinity-dependent and is controlled by feedback from downstream pH and turbidity instruments. For soft surface water with total alkalinity below 40 mg/L as CaCO₃, a dose of 5–15 mg/L of 100% NaOH may be required to reach pH 8.0–8.5; the exact dose is confirmed by jar testing because humic substances and dissolved CO₂ consume alkali. The chemical is specified under EN 896:2012 for drinking water treatment in the European Union and AWWA B501-19 in North America, with impurities such as mercury, lead, and arsenic controlled to regulatory limits. Terminal product types include potable water, boiler feedwater make-up, cooling tower make-up, and demineralization pretreatment. An operational limitation is the incompatibility of concentrated caustic with aluminum and galvanized piping; the distribution system from the dosing skid to the injection point is constructed in PP, PVDF, or lined carbon steel to prevent corrosion and hydrogen evolution at high pH.
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Aditya Birla Grasim Caustic Soda Flakes is a white, deliquescent solid form of anhydrous sodium hydroxide produced by concentrating membrane-cell caustic lye and flaking the melt on a cooled drum. The commercial designations correspond to technical grade and rayon grade solid sodium hydroxide, with CAS 1310-73-2, UN 1823, EINECS 215-185-5, IMDG Class 8, and hazard statement H314. Solid density is approximately 2.13 g/cm³, melting point is near 318 °C, and solubility in water exceeds 100 g/100 mL at 20 °C. Because the product originates from membrane-cell electrolysis rather than diaphragm or mercury cells, it carries lower sodium chloride and sodium chlorate residuals, and it does not carry mercury-cell contamination. This makes the flake suitable for chloride-sensitive textile spin baths, soap saponification, and closed-loop alumina liquor make-up where impurity accumulation is controlled. The material is supplied in moisture-barrier bags, typically 25 kg or 50 kg net weight, with an inner polyethylene liner to limit carbon dioxide absorption and water uptake.
Certificates of analysis for the flake grade are commonly generated according to ASTM E291-18 or IS 252:2013. Total alkalinity is converted to sodium hydroxide content, sodium carbonate is determined by double-indicator titration or an equivalent method, and sodium chloride is measured by argentometric titration, ion chromatography, or potentiometric titration. The typical technical flake specification is 99.5% w/w NaOH minimum, 0.5% w/w Na2CO3 maximum, 0.1% w/w NaCl maximum, and 20 mg/kg iron maximum. Membrane-cell 50% lye is normally specified at 48.0–50.0% w/w NaOH with sodium chloride around 0.02–0.05% w/w. Evaporation of lye to flake can relatively enrich non-volatile sodium chloride and sodium carbonate in the dry product, so a direct substitution of flake for lye must be evaluated for chloride-sensitive recipes and for rayon-grade applications where lower iron and sodium chloride limits are contractually fixed.
| Parameter | Aditya Birla Grasim Caustic Soda Flakes | Membrane-Cell 50% Lye | Diaphragm-Cell Solid Reference |
|---|---|---|---|
| Sodium hydroxide | 99.5% w/w min | 48.0–50.0% w/w NaOH | 96.0–98.5% w/w typical |
| Sodium chloride | 0.1% w/w max | 0.02–0.05% w/w typical | 0.4–1.0% w/w typical |
| Sodium carbonate | 0.5% w/w max | 0.2% w/w max | 0.4–1.0% w/w typical |
| Iron | 20 mg/kg max | 1–5 mg/kg typical | 20–50 mg/kg typical |
| Mercury | Not detected | Not detected | Not detected |
The flake form differs from prilled or granular caustic soda in particle geometry and dissolution surface area. Flakes are plate-like solids with high exposed surface area per unit mass, which accelerates dissolution in agitated tanks but increases bridging tendency in hoppers and screw feeders. Prills and granules generally flow more uniformly from bulk storage and may be preferred for automated dosing systems where mass-flow hoppers are used. The absence of water in the flake lowers freight mass compared with 50% lye, but anhydrous handling requires stricter protection against moisture and atmospheric carbon dioxide. In direct comparison with diaphragm-cell solid, the membrane-cell flake reduces sodium chloride and iron entering the end-use process, which is materially important in rayon spin baths and in high-purity chemical synthesis.
The enthalpy of solution of sodium hydroxide in water is approximately −44 kJ/mol at infinite dilution. Preparation of a 1 mol/L solution can raise water temperature by roughly 10 °C under adiabatic conditions. Process vessels should therefore be sized for the heat of solution and vented before mixing begins. The solid flake must be added to water in a mechanically stirred tank, not the reverse, because adding water to a mass of solid can generate localised boiling and caustic spray. For preparation of 50% w/w mother liquor from flakes, continuous dissolving systems normally use chilled water at 5–15 °C and external cooling to hold the liquid below 60 °C when high-density polyethylene tanks are used. Carbon steel is generally suitable for caustic solutions below 60–70 °C, while austenitic stainless steel can undergo stress corrosion cracking in hot caustic above 80 °C if tensile stress and chloride contamination are simultaneously present. Nickel alloys are specified for elevated-temperature evaporator and dissolver service. In storage, opened flake bags must be reclosed immediately; the product deliquesces in humid air, and atmospheric carbon dioxide progressively converts surface sodium hydroxide to sodium carbonate.
Viscose fibre production uses caustic soda in the steeping and alkalization of cellulose to form alkali cellulose. Rayon-grade caustic must limit iron because iron can catalyse degradation of the cellulose chain and reduce viscose filterability. The membrane-cell flake is specified around 20 mg/kg iron maximum and is often supplied against tighter lot-specific limits. Diaphragm-cell solid can carry 0.4–1.0% w/w sodium chloride and 20–50 mg/kg iron into the process, which increases salt load in recovery circuits and can interfere with spin-bath control. Sodium chlorate generated in diaphragm cells is an undesirable oxidant in acid spin baths; membrane-cell flake has a lower chlorate profile because the cell chemistry is separated by an ion-exchange membrane. Replacing diaphragm-cell solid with membrane-cell flake therefore changes the plant sodium chloride mass balance and may require adjustment of recovery circuit purge rates. Published data for exact sodium chlorate limits in supplier-specific rayon-grade flakes is limited, and the required maximum must be confirmed against the buyer specification and lot certificate rather than assumed from the general technical grade.
Cotton mercerization uses 20–25% w/w NaOH at 15–25 °C. The flake is dissolved to the required target concentration before use, and the caustic strength is verified by titration or density measurement. In soap saponification, the theoretical sodium hydroxide requirement is calculated from the saponification value: NaOH mass per gram of oil follows from (saponification value / 56.1) × 40.0. The flake charge is then adjusted for the free caustic specification of the finished soap. For alumina refinery digestion, sodium hydroxide is normally supplied as lye, but flakes are used for make-up when liquid logistics are constrained or when site storage favours dry alkali. The flake must meet low chloride and low iron limits because these impurities accumulate in closed Bayer liquor circuits and influence precipitation yield and product quality. The heat of dissolution of flakes must be included in the energy balance of make-up dissolving tanks, particularly when large batch additions are made.
At ambient to moderately warm temperatures, 304 and 316 stainless steels can handle many caustic solutions, but stress corrosion cracking risk increases near 80–100 °C. Residual tensile stress from welding and chloride contamination further reduce the operating envelope. Carbon steel is preferred for many low-temperature storage and transfer applications, while hot caustic service above 80 °C may require stress-relieved carbon steel or nickel-rich alloys depending on concentration and velocity. Aluminium, zinc, galvanized steel, tin, and magnesium alloys are not acceptable because sodium hydroxide attacks these metals and releases hydrogen. Gaskets and seals should be EPDM or PTFE; polyacetal and polyamide are unsuitable in continuous hot caustic. Transfer lines should be self-draining and heat-traced if a 50% solution is produced at ambient temperatures below 12 °C, because 50% caustic lye has a freezing point near 12 °C. The solid flake does not freeze, but moisture ingress can create surface solution that crystallizes at low temperature and binds the flakes into a solid mass.
Regulatory classification follows sodium hydroxide as a single-substance chemical. The material is registered under REACH, and packaging is UN-approved for Class 8 corrosive solid transport. Wastewater neutralization must bring discharge pH to the local regulatory range, commonly 6–9, before release. Neutralization should be carried out in a controlled stirred tank with appropriate cooling because neutralization with mineral acids also releases heat. For spills, the solid should be collected dry where possible, and residues should be flushed with water only after ensuring that drainage flows to a neutralization system or compatible collection basin.
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