| HS Code | 278210 |
| Product Name | Meghmani Caustic Soda Flakes |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Molecular Weight | 40.00 g/mol |
| Appearance | White flakes |
| Purity | 99% min |
| Melting Point | 318°C |
| Boiling Point | 1388°C |
| Specific Gravity | 2.13 |
| Solubility In Water | 111 g/100 mL at 20°C |
| Ph 1 Percent Solution | 13-14 |
| Odor | Odorless |
As an accredited Meghmani Caustic Soda Flakes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Meghmani Caustic Soda Flakes are packaged in strong HDPE woven bags with inner liner, each containing 25 kg net weight. |
| Container Loading (20′ FCL) | 20' FCL loading of Meghmani Caustic Soda Flakes: packed in 25kg bags, palletized, secured, with moisture-proof lining and proper ventilation. |
| Shipping | Meghmani Caustic Soda Flakes are shipped as UN1823, Class 8 corrosive solid. Packed in 25 kg moisture-proof bags on pallets, then loaded into clean, dry containers. Stow away from moisture and incompatible materials. Handle with PPE, ensure ventilation, and follow all hazardous transport regulations. |
| Storage | Store Meghmani Caustic Soda Flakes in a cool, dry, well-ventilated area away from moisture, heat, and direct sunlight. Keep containers tightly sealed, preferably in original packaging or corrosion-resistant receptacles. Store on pallets off the floor, away from acids, organic materials, and reactive metals like aluminum. Ensure proper labeling and spill containment to prevent accidental exposure. |
| Shelf Life | Shelf life: 24 months when stored unopened in original packaging, kept dry, cool, and away from moisture. |
In alumina refineries, Meghmani Caustic Soda Flakes are restored to Bayer spent liquor at the causticisation step rather than dissolved in raw water, because raw-water dissolution dilutes the alumina-to-caustic ratio and forces additional evaporation load downstream. A typical digestion circuit for gibbsitic bauxite operates at 140–160°C with caustic concentrations from 120 g/L to 160 g/L Na₂O equivalent; boehmitic and diasporic ores require 200–240°C and 240–270°C respectively. Flake is discharged from supersacks into a rubber-lined carbon steel dissolution tank fitted with a 45-degree pitched-blade turbine agitator at 100–150 rpm and heated by spent liquor at 60–85°C. The heat of solution of anhydrous sodium hydroxide is 44.5 kJ/mol; if dissolution is batch-charged faster than 25 kg/min per m³ of liquor, local temperature excursions above 95°C can trigger silicate scaling on vessel walls. Impurity levels in flake influence Bayer heat-exchanger fouling: sodium carbonate above 1.5 wt% in the incoming flake increases calcium carbonate scale on digester heater tubes, while chloride above 0.3 wt% accelerates pitting in stainless steel heater shells. These limits are checked by ASTM E291-18 on a lot-by-lot basis. The digested liquor is clarified in thickeners and filtered through security filters; precipitated alumina trihydrate is then washed, dried at 105–120°C, and calcined to smelter-grade alumina at 950–1050°C. The terminal product is metallurgical alumina used in Hall-Héroult smelting.
| Bauxite mineralogy | Digester temperature (°C) | Caustic concentration as Na₂O (g/L) | Alumina-to-caustic ratio (unitless) |
|---|---|---|---|
| Gibbsitic | 140–160 | 120–160 | 0.60–0.70 |
| Boehmitic | 200–240 | 200–260 | 0.30–0.50 |
| Diasporic | 240–270 | 220–280 | 0.25–0.40 |
Published plant data for Meghmani flake in diasporic circuits is limited; the mill control bands above are representative of international Bayer plant operating ranges.
Saponification of palm stearin or tallow with flake-derived sodium hydroxide follows a three-phase reaction in which the rate-limiting step is triglyceride hydrolysis at the oil–aqueous interface. Batch soap kettles using a blend of palm stearin (saponification value 196–205 mg KOH/g) and palm kernel oil (saponification value 240–250 mg KOH/g) are dosed according to the mass balance: NaOH (kg) = 0.7129 × saponification value (mg KOH/g) × oil mass (kg) ÷ 1000, plus a 5–8% excess to ensure complete saponification. A 198 mg KOH/g tallow charge therefore requires 141.2 kg NaOH per metric ton oil on a 100% basis, or 148–152 kg per metric ton at 5–8% excess. Flake is dissolved to 25–35 wt% NaOH lye at 60–70°C in a carbon steel tank fitted with a slow-speed anchor agitator (20–40 rpm) to limit foam generation. The lye is pumped through a plate heat exchanger and introduced beneath the oil phase at 75–85°C over 45–90 minutes. Overdosing beyond 10% excess produces brittle soap with free alkali above 0.05% w/w; underdosing below 3% excess leaves unreacted oil pockets that exude during milling and lower soap hardness. Free caustic alkalinity is determined by AOCS Da 4a-48, and the saponification value of the incoming oil is verified by AOCS Cd 3-25. The terminal product is either neat soap or vacuum-dried soap noodles; the split glycerin phase is sent to evaporation at 28–35 wt% glycerol.
Open-width mercerising ranges require a narrow caustic concentration window between 280 g/L and 320 g/L NaOH, approximately 24–26°Bé, to achieve controlled cotton fibre swelling without destroying the primary cell wall. The caustic saturator is maintained at 18–23°C with tension set at 3–4% and dwell time between 40 seconds and 60 seconds. At concentrations below 260 g/L, the degree of mercerisation measured by barium activity number under AATCC TM 89 remains below 115, corresponding to incomplete soda-cellulose II conversion; above 330 g/L, fabric tensile strength loss increases and the cold pad bath viscosity rises enough to alter liquor pick-up on the pad mangle. Flake-derived sodium carbonate should remain below 1.0 wt% because carbonate precipitates as sodium bicarbonate on guide rolls in the chilled saturator. The fabric then passes through a stabilisation section where hot-water washing at 70–85°C removes alkali. Residual alkali on the fabric is titrated and must fall below 0.05% as NaOH on fabric mass before drying. The terminal product is dimensionally stable, high-luster mercerised cotton for shirting, sheeting, and covered-elastane knits.
Caustic flake is reconstituted to 2.0–4.0 wt% NaOH for recirculating CIP circuits in dairy evaporators, where the target is removal of denatured whey protein films rather than scale dissolution. At 75–82°C, caustic contact for 20–30 min at a flow velocity of 1.5–2.5 m/s removes protein soil; addition of 0.05–0.15 wt% sodium gluconate prevents calcium phosphate precipitation inside spray ball nozzles. Food-contact surfaces must be rinsed to pH neutral before product contact under FDA 21 CFR 178.1010; sodium hydroxide may be used as a pH control agent in food processing under FDA 21 CFR 184.1763. The terminal requirement is clean stainless steel surface verified by ATP bioluminescence surface swab after rinse.
When flake caustic replaces a 25 wt% liquid caustic feedstock in methoxide makeup, the operator must manage the dissolution water balance because the substitution reaction releases 0.45 kg water per kg NaOH, and free water above 0.25 wt% in the finished methoxide shifts transesterification toward soap formation. In a 10 t/day batch unit, 50 kg flake NaOH is added to 200 kg methanol at 40–45°C over 60–90 minutes with a sealed high-shear mixer. The resulting catalyst is dosed at 0.5–1.0 wt% NaOH equivalent on oil basis into a 6:1 methanol-to-refined oil molar ratio stream at 60–65°C. Refined oil total acid number must be below 0.5 mg KOH/g to avoid excess soap; free fatty acid content above 0.25 wt% consumes catalyst and reduces methyl ester yield. The reaction reaches approximately 98% conversion within 60 minutes; ester content in the washed biodiesel is measured by EN 14103:2020 and final fuel properties by ASTM D6751-23a. The terminal products are fatty acid methyl esters and crude glycerin. Exposed flake at RH >60% can absorb more than 1.0 wt% moisture within 24 h; therefore methoxide makeup systems use sealed supersack discharge and methanol pre-charge to prevent water carryover into the reactor.
In acidic wastewater neutralisation, flake caustic is first diluted to a 20–25 wt% master solution because direct flake addition onto a pH probe causes localised pH excursions above 12 and calcium sulphate blinding of the sensor. The solution is metered through a positive displacement dosing pump controlled by two-stage pH cascade: coarse feed at pH <4.5, trim feed at pH 5.5–6.5. Target discharge is pH 6.5–9.0 for most municipal or industrial permits; for sulfuric acid effluent, the reaction produces sodium sulfate and can raise tank temperature by 15–20°C depending on acid concentration. Caustic soda for potable and wastewater applications is specified under AWWA B501-19. The terminal product is neutralised brine or sodium sulfate solution that is discharged, evaporated, or routed to biological treatment.
Competitive Meghmani Caustic Soda Flakes prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to sales3@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: sales3@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Meghmani Caustic Soda Flakes is a solid hygroscopic sodium hydroxide product manufactured by membrane-cell electrolysis of purified brine, followed by evaporative concentration, molten handling, and flaking on cooled drum contact surfaces. The product is identified by the chemical name sodium hydroxide, CAS Registry Number 1310-73-2, EINECS 215-185-5, and transport classification UN 1823, Class 8, Packing Group II. It is not assigned a discrete model number; the commercial designation refers to the membrane-cell grade, flake physical form, and the sodium hydroxide assay. The flake form is selected where solid inventory control, reduced water freight, or direct low-moisture dosing is required. Sodium hydroxide flakes are white to off-white deliquescent solids with a molecular weight of 40.00 g/mol, melting point 318 °C, boiling point 1388 °C, and true specific gravity approximately 2.13. The bulk density of commercial flakes is lower than true density, typically in the range 0.9–1.1 kg/L depending on flake size distribution and packing. Aqueous solubility is high, approximately 111 g per 100 mL water at 20 °C, with significant heat release on dissolution. The product absorbs atmospheric moisture and carbon dioxide, forming surface carbonate and caking if exposed to humid air. The following technical description covers specification parameters, differences from alternative caustic soda grades, dissolution practice, downstream uses, and operational limitations.
Because the material is deliquescent, open-bag storage at relative humidity above 60% produces surface absorption and bridging in hoppers. Closed-top bins, moisture purge, and first-in-first-out stock rotation are used in production-scale storage. Specification compliance should always be cross-checked against the batch-specific certificate of analysis and the current safety data sheet, since re-test intervals and regional packaging variants can alter the documented parameter set.
The distinction originates in the electrolytic cell design. In membrane-cell production, a perfluorinated cation-exchange membrane separates anolyte and catholyte compartments, permitting sodium ion transport while restricting chloride back-migration. The resulting sodium hydroxide stream contains substantially less sodium chloride and sodium chlorate than diaphragm-cell product. Commercial membrane-grade flakes commonly specify sodium chloride at ≤0.2% by mass, whereas diaphragm-grade solid material may contain sodium chloride in the range 0.5–1.0% by mass and higher chlorate values. Mercury-cell product is also high-purity, but mercury residue and international phaseout programs make membrane-cell material the preferred feedstock where food-contact, pharmaceutical-intermediate, or high-purity polymer processes impose low heavy-metal requirements. Meghmani Caustic Soda Flakes is produced by membrane-cell technology, which reduces chloride and heavy-metal burden relative to diaphragm material.
Differences from liquid caustic soda are equally significant. A 50% liquid caustic soda solution carries roughly half its mass as water, while flake product retains only low residual moisture, reducing freight mass and ambient storage demand. However, solid handling requires dry feed systems or controlled dissolution, and the flakes generate substantial heat on wetting. Compared with prilled or micropearl sodium hydroxide, flakes can exhibit wider particle size distribution and greater dust generation, but they retain lower friability and are suited to direct manual or semi-automated charge operations where dissolution vessel design permits slow addition. Selection among flake, prill, and liquid is therefore driven by logistics, dosing accuracy, and the energy balance of the receiving process rather than by any single purity advantage.
The trade specification below reflects typical membrane-cell caustic soda flake parameters; actual batch certificates control. The product is ordinarily packed in 25 kg and 50 kg laminated high-density polyethylene bags with outer woven polypropylene, or in 500 kg and 1000 kg FIBCs fitted with moisture barriers. Storage should be on dry, covered racking away from acids, aluminum, zinc, and galvanized surfaces. Bulk handling equipment should be stainless steel Type 316L or approved polymer-lined carbon steel.
| Parameter | Typical limit | Method |
|---|---|---|
| Total alkalinity as NaOH | ≥ 99.5% by mass | ASTM E291-18, titrimetric |
| Sodium carbonate as Na₂CO₃ | ≤ 0.5% by mass | ASTM E291-18 / IS 252:2013 |
| Sodium chloride as NaCl | ≤ 0.2% by mass | ASTM E291-18 |
| Iron as Fe | ≤ 50 ppm | ASTM E291-18, spectrophotometric |
The sodium hydroxide content is determined by acid-base titration and expressed as total alkalinity; the result includes sodium carbonate and is corrected by separate carbonate determination. The values above are used for energy-balance and mass-balance calculations but do not substitute for the safety data sheet or batch-specific analysis.
Dissolution of solid sodium hydroxide in water is strongly exothermic; the integral enthalpy of solution at infinite dilution is approximately −44.51 kJ/mol. In a continuous neutralisation train, flake addition rate must be matched to jacket or external heat exchanger duty, because the adiabatic temperature rise of a concentrated solution can exceed 100 °C at atmospheric pressure if flakes are added faster than heat removal capacity. A typical dissolution skid consists of a stainless steel Type 316L tank, top-entry or side-entry agitation, a variable-frequency flake screw feeder, a conductivity or density loop for concentration feedback, and a recirculation cooler sized for the peak exotherm. The flakes are charged into the vortex of water at controlled temperature; reverse addition of water to a static mass of solid is prohibited because localized boiling and splattering can occur.
Dissolution rate is limited by surface area, bulk water temperature, and agitation. Use of warm process water at 35–50 °C accelerates dissolution but requires additional cooling capacity. For 50% final concentration, the resulting solution is highly alkaline and corrosive. Materials of construction downstream of the dissolution point should avoid aluminum, zinc, tin, and galvanized steel; stainless steel Type 316L, high-density polyethylene, fiberglass-reinforced plastic, and rubber-lined carbon steel are suitable for ambient-temperature storage. If the neutralisation target is a weak acid such as acetic acid, the heat of reaction adds to the heat of dilution; the vessel cooling load must be calculated from both enthalpy terms. In sulfide precipitation or pH correction duty, the flake form permits solid inventory without large lye storage tanks but increases operator exposure potential during bag handling and hopper charging.
In Bayer-process alumina refining, sodium hydroxide is used to dissolve gibbsitic and boehmitic aluminum hydroxide from bauxite at elevated temperature and pressure. The flake product is dissolved into spent liquor to maintain the sodium oxide-to-alumina molar ratio in the digester feed. Low chloride and iron input from membrane-cell flakes reduces impurity accumulation in the closed liquor loop, which is significant because chloride promotes pitting corrosion in heat exchangers and flash tanks. The required specific caustic consumption depends on bauxite mineralogy and is determined by plant mass balance rather than by flake specification alone.
In kraft pulp and paper operations, sodium hydroxide flakes are combined with sodium sulfide to generate white liquor. The causticity and sulfidity of the white liquor are controlled parameters; flake purity affects the inert carbonate load entering the lime cycle. In soap and surfactant manufacture, the flake is used for saponification of triglycerides. The stoichiometric requirement is 3 mol sodium hydroxide per 1 mol triglyceride, though practical formulations may use excess caustic or dual-stage addition to drive the reaction and achieve target free alkali. In textile mercerization, sodium hydroxide concentrations in the range of 20–25% w/w are typical for cotton mercerizing; flake-dissolved caustic must be low in transition metals to avoid fabric staining and peroxide decomposition in subsequent bleaching. In water treatment and industrial cleaning, flake sodium hydroxide is used to raise alkalinity, soften water, neutralize acidic waste streams, and remove organic soils. For these applications the product is generally dissolved before use, and the user is responsible for verifying compatibility with surfactants, chelating agents, and wetting additives.
Occupational exposure to sodium hydroxide mist or dust is controlled under the OSHA permissible exposure limit of 2 mg/m³ as an 8-hour time-weighted average, listed in 29 CFR 1910.1000 Table Z-1. Process areas handling flakes should be equipped with local exhaust ventilation or dust suppression; wet methods reduce airborne dust but generate corrosive floor films. Direct contact with skin or eyes produces liquefactive necrosis; a full-face shield, chemical splash goggles, neoprene or PVC gauntlets, and alkali-resistant clothing are required during bag breaking, hopper charging, and dissolving. Emergency showers and eyewash stations should conform to ANSI/ISEA Z358.1. The product is incompatible with strong acids, ammonium salts, chlorinated solvents, nitro compounds, and light metals including aluminum, zinc, tin, and magnesium. Contact with acids releases heat and may cause violent boiling; contact with ammonium salts releases ammonia. Under no circumstances should flake caustic soda be combined with amine-based additives in high-temperature neutralisation, because exothermic neutralisation and ammonia evolution can lead to uncontrolled pressure or vapor release. Storage tanks should be vented to a scrubbed or safe location, and transfer lines should be sloped to drain to prevent dead-leg solidification.
| Control area | Parameter | Reference |
|---|---|---|
| Chemical identity | Sodium hydroxide, CAS 1310-73-2 | REACH regulation; CLP inventory |
| Transport classification | UN 1823, Class 8, Packing Group II | UN model regulations |
| EU hazard classification | Skin Corr. 1A, H314 | CLP Regulation |
| Occupational exposure limit | 2 mg/m³ | 29 CFR 1910.1000 Table Z-1 |
| Product specification | Caustic soda flakes | IS 252:2013 |
| Test method | Total alkalinity, chloride, iron | ASTM E291-18 |
Batch-to-batch variation in flake moisture and particle size distribution can affect screw feeder accuracy and dissolution rate. At relative humidity above 60%, hopper pre-drying or inert gas purge is required to prevent bridging and caking. The product should not be left in open bags; resealing and dry transfer are necessary. For applications requiring low nickel, low silica, or controlled particle size, the certificate of analysis should be reviewed for the specific lot, because published data for this specific configuration is limited. Plant-scale solubility tests are recommended when switching from liquid caustic soda to flakes, because the point-of-use dissolution system must accommodate both the exotherm and the residual impurity profile. Until such verification is complete, batch-controlled feed rates and closed transfer remain the operative control measures.
Committed to quality, innovation, and reliable chemical solutions for a sustainable future.
