| HS Code | 293852 |
| Product Name | Xinjiang Tianye Caustic Soda Flakes |
| Chemical Formula | NaOH |
| Cas Number | 1310-73-2 |
| Appearance | White solid flakes |
| Purity | 99% minimum |
| Molecular Weight | 40.00 g/mol |
| Melting Point | 318 °C (604 °F) |
| Boiling Point | 1,388 °C (2,530 °F) |
| Density | 2.13 g/cm³ at 25 °C |
| Solubility In Water | 111 g/100 mL at 20 °C |
| Ph 1 Percent Solution | 13–14 |
| Hygroscopicity | Hygroscopic; absorbs moisture and carbon dioxide from air |
| Odor | Odorless |
As an accredited Xinjiang Tianye Caustic Soda Flakes factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | 25kg caustic soda flakes packaged in double-layer PP woven bags with inner PE liner, sealed, labeled, and palletized. |
| Container Loading (20′ FCL) | 20′ FCL loading of Xinjiang Tianye caustic soda flakes in palletized, heat-sealed bags, secured upright for safe transit. |
| Shipping | Xinjiang Tianye Caustic Soda Flakes ship in 25kg PP/PE woven bags, loaded into ventilated 20ft or 40ft containers. Protect from moisture, humidity, and acids during transit. Handle with care to avoid bag damage; ensure proper labeling and segregation from incompatible materials. |
| Storage | Store Xinjiang Tianye Caustic Soda Flakes in a cool, dry, well-ventilated area, tightly sealed in original or compatible containers. Keep away from moisture, water, acids, and incompatible materials. Use proper bunding or pallets to prevent floor contact. Ensure spill containment and clearly label storage zones. Always wear appropriate PPE when handling. |
| Shelf Life | Shelf life is typically 2 years when stored sealed in a dry, cool place, protected from moisture and contamination. |
In alumina refinery causticization circuits, Xinjiang Tianye caustic soda flakes are introduced as solid make-up into spent liquor return lines at 80–105 °C before digestion feed tanks. The addition point is selected to avoid local supersaturation and to reduce erosion-corrosion on high-flow transfer pumps. Maintaining free Na2O at 220–260 g/L for boehmitic and diasporic bauxite digesters is required; the corresponding alumina-to-caustic molar ratio is held between 0.62 and 0.72 in continuous tube digesters operating at 240–280 °C and 5.5–6.5 MPa. Make-up NaOH consumption recorded on production lines using bauxite with reactive silica of 4–7 wt% ranges from 60–120 kg NaOH per metric ton of smelter-grade alumina, because sodium is lost as desilication product in blow-down. Higher silica bauxites push make-up demand above 120 kg/t; lower levels below 60 kg/t are observed only with gibbsitic bauxite and low-temperature digestion near 140–160 °C. Incoming flake quality is screened against GB/T 209-2018 solid caustic soda limits and refinery chloride budgets; chloride above 0.5 wt% NaCl in make-up is rejected by most alumina mills because it concentrates in liquor and accelerates pitting of steam-heated digestion heaters. Terminal outputs from the caustic-driven circuit include smelter-grade alumina for Hall–Héroult cells, fine hydrate for water treatment coagulants, and zeolite synthesis feedstock, with the flake type selected for low iron and low chloride rather than low carbonate.
Incoming solid caustic soda compliance envelope for high-pressure Bayer digestion:
| Parameter | Standard basis | High-pressure Bayer acceptance window |
|---|---|---|
| NaOH | GB/T 209-2018 | ≥ 99.0 wt% |
| NaCl | GB/T 209-2018 | ≤ 0.05 wt% |
| Fe2O3 | GB/T 209-2018 | ≤ 0.008 wt% |
| Na2CO3 | GB/T 209-2018 | ≤ 0.8 wt% |
Kraft fibre line alkali balance uses flake NaOH not as a primary pulping chemical but as a fortifying agent for weak white liquor after causticizing losses and sodium/sulfur imbalance corrections. The white liquor charge, expressed as effective alkali on an NaOH basis to align with flake metering, is maintained at 18–24% on oven-dry wood for softwood and 12–18% for hardwood, corresponding to 180–284 kg NaOH per oven-dry tonne for softwood at the upper bound. Causticizing efficiency, measured by the ABC test under TAPPI T 624 cm-21, is kept above 82–85% to avoid dead-load sodium carbonate entering the digester. Addition of flake caustic into weak liquor storage at 70–85 °C raises effective alkali without raising sulfide, allowing correction of sulfidity to 25–35%. The downstream production process is continuous alkaline delignification in single-vessel or two-vessel digesters at 150–170 °C, with H-factor controlled from 1,200–2,200 for bleachable hardwood grades, followed by blowing, washing, oxygen delignification, and chlorine dioxide bleaching under ISO 302:2004 Kappa number control. Terminal products include bleached hardwood and softwood market pulp, dissolving pulp for rayon, and unbleached linerboard-grade pulp. A common failure mode observed on fibre lines is scaling of black liquor evaporators when flake addition is too aggressive and carbonate dead load rises above 15 g/L Na2CO3; this reduces heat transfer and forces boilout cycles.
Cotton mercerization with caustic soda flakes requires dissolving the solid to a 50 wt% mother liquor and then diluting it into a mercerizing range of 18–24 wt% NaOH, equivalent to 24–31°Bé at 15–25 °C. At this concentration, the cotton cellulose lattice transitions from cellulose I to alkali cellulose and then recrystallizes to cellulose II after tension-controlled washing; the targeted sodium hydroxide addition is 350–420 kg NaOH per metric ton of dry cotton fabric when pumping from 50 wt% stock, with bath renewal based on titration to maintain 200–250 g/L NaOH. The wetting agent dose is 0.2–0.5 g/L, and the goods-to-liquor ratio is held at 1:4 to 1:8. Downstream production equipment includes a chain mercerizing frame with width control, temperature-controlled caustic troughs, and countercurrent rinse sections at 65–85 °C. In actual operations, luster variation occurs if caustic activity falls below 16 wt% or if bath temperature exceeds 30 °C, because swelling becomes non-uniform; frame pin breakage increases when tension control exceeds 1.5 cN/dtex on lightweight fabrics. Compliance is evaluated through fabric tensile strength testing under ASTM D5034-21 and dimensional stability under AATCC 135-2020, with residual caustic in fabric limited to below 0.05 wt% after neutralization. Terminal products include mercerized cotton poplin, sateen, high-tenacity sewing thread, and warp yarn for reactive dyeing, where increased dye uptake and lower pilling are specified by garment manufacturers.
Continuous sweetening of LPG and light straight-run naphtha uses a regenerable caustic phase at 5–12 wt% NaOH in a packed prewash column operated at 30–45 °C and 1.2–2.5 MPa to extract hydrogen sulfide and low-molecular-weight mercaptans before the Merox oxidation section. Xinjiang Tianye flakes are dissolved in a dedicated caustic dissolving skid with softened water to a 20–25 wt% NaOH mother liquor and injected at 0.2–0.5 vol% of the hydrocarbon feed rate; spent caustic purge is maintained at 0.5–2.0 vol% of circulating inventory per day depending on sulfur load. The addition ratio is governed by mercaptan sulfur in feed, typically 150–1,500 mg/kg; the caustic-to-mercaptan molar excess is held at 3:1 to 5:1 in extraction, while regeneration air flow is controlled to achieve disulfide separation without caustic carryover. Compliance for treated LPG hydrogen sulfide content is tested by ASTM D2420-21, and process safety for caustic handling follows API RP 2009. Downstream production includes caustic prewash, Merox extraction, air oxidation of sodium mercaptides to disulfides, and disulfide separation, after which the regenerated caustic is recycled. Terminal products are low-sulfur LPG, sweet naphtha for catalytic reforming, and low-mercaptan jet fuel blending components. A production-line failure observed in this circuit is sodium naphthenate emulsification in the spent caustic knock-out drum when purge rate is reduced below 0.5% and organic acid salt accumulation increases interfacial tension; the resulting carryover forces unit cutbacks and solvent washing of downstream coalescers.
Batch and continuous soap saponification with Xinjiang Tianye flake caustic requires dissolving to 38–50 wt% NaOH in low-chloride process water before metering into molten triglyceride blends at 70–90 °C under reflux. The stoichiometric dry flake requirement is derived from the saponification value: NaOH (g) = SAP (mg KOH/g) × 0.000713 × oil mass (g). For a tallow/coconut oil blend with SAP of 190–210 mg KOH/g, the theoretical NaOH charge is 13.5–15.0% by oil mass; industrial kettles run 0.5–2.0 wt% excess NaOH over stoichiometry to force complete triglyceride conversion, then reduce free caustic in the neat soap to 0.05–0.10 wt% by back-neutralization with citric acid or stearic acid. The downstream process includes high-shear mixing, salting-out with sodium chloride, neat soap separation from spent lye, vacuum spray drying at 110–130 °C, and plodding/extrusion. Compliance is evaluated under ASTM D460-22 for soap sampling and chemical analysis, with free caustic alkalinity measured by titration and reported as NaOH. Terminal products include toilet soap base, laundry soap bars, and industrial soap noodles. A processing limitation observed in production is localized overheating and discoloration when dry flakes are added too quickly to low-water oil phases; dissolution exotherm can raise temperature above 140 °C and darken unsaturated tallow fractions, so continuous saponification lines pre-mix caustic solution to 40 wt% and control injection to avoid local excess.
Caustic soda flakes used for pH correction of demineralized and reverse-osmosis permeate are dissolved to a 0.1–0.5 wt% NaOH dosing solution to prevent localized high pH excursions and to allow precise metering by diaphragm pumps into static mixers. In a water stream with residual CO2 concentration of 2–15 mg/L and alkalinity of 5–20 mg/L as CaCO3, pH lift from 6.8 to 8.2 requires 2–10 mg/L NaOH as 100% basis, depending on temperature and CO2 equilibrium; plant-specific dose is confirmed by titration because published data for this specific configuration is limited. Compliance governing caustic soda in municipal and industrial water treatment is ANSI/AWWA B501-19; carbon dioxide and bicarbonate equilibria are monitored by ASTM D513-19. The downstream production process includes a stored 25–50 wt% caustic mother liquor in HDPE or FRP tanks, a metering pump, static mixer, and a pH analyzer with sample lag compensation. Terminal products are corrosion-protective potable water, low-silica boiler feedwater for high-pressure steam generation, and closed-loop district heating make-up. The operational boundary is strict: direct dosing of concentrated caustic into aluminum fittings or unlined carbon steel is incompatible because hydrogen evolution and stress corrosion cracking can occur; winter shutdowns require heat tracing when the mother liquor concentration exceeds 50 wt% because the freezing point rises and crystal deposition plugs diaphragm check valves.
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Xinjiang Tianye Caustic Soda Flakes are industrial-grade solid sodium hydroxide, CAS 1310-73-2, UN 1823, Hazard Class 8, Packing Group II, produced at the membrane-cell chlor-alkali complex in Shihezi, Xinjiang. The product is specified as Grade I solid flake under GB/T 209-2018; published technical documents for this specific product do not assign a separate proprietary numeric model beyond the Grade I membrane-cell flake designation. Nominal specification limits are NaOH ≥ 99.0% w/w, Na2CO3 ≤ 0.5%, NaCl ≤ 0.03%, Fe2O3 ≤ 0.005%. The material is produced by multi-effect evaporation of membrane-cell 32% NaOH liquor, followed by drum flaking; the flake form is intended for bag charging, batch dissolver feed, and installations where freezing of 50% liquid caustic is a logistical constraint.
| Parameter | Unit | Grade I limit | Test basis |
|---|---|---|---|
| Total alkalinity as NaOH | % w/w | ≥99.0 | GB/T 209-2018 |
| Sodium carbonate as Na2CO3 | % w/w | ≤0.5 | GB/T 209-2018 |
| Sodium chloride as NaCl | % w/w | ≤0.03 | GB/T 209-2018 |
| Iron as Fe2O3 | % w/w | ≤0.005 | GB/T 209-2018 |
| Appearance | — | White or near-white flakes, no visible mechanical impurities | Visual inspection per GB/T 209-2018 |
The Grade I limits differentiate this product from Grade II and Grade III solid sodium hydroxide under the same standard; Grade II permits NaCl up to 0.05%, and Grade III permits NaCl up to 0.08%. The low chloride and iron ceilings are significant in closed-loop industrial circuits where impurity accumulation controls heat exchanger corrosion, salt precipitation, and final product contamination. The solid has a particle density of approximately 2.13 g/cm3, and the flake bulk density is typically 0.9–1.1 kg/L. Published particle-size and dissolution-rate data for this specific Xinjiang Tianye flake product are limited; process design should rely on lot-specific certificates of analysis and on-site dissolution trials rather than generalized flake data.
When flakes are charged directly into closed dosing skids, the limiting factors are heat release, local concentration gradients, and solid bridging. Dissolution of unmilled flakes proceeds more slowly than micropearl dissolution because the geometric surface area per kilogram is lower; uncooled tanks may develop hot spots near the addition port because the enthalpy of solution of NaOH is approximately −44.5 kJ/mol. For a target solution strength of 20–25% NaOH, standard practice is to charge flakes onto the surface of a mechanically agitated tank at 250–400 rpm, with external cooling or a recirculation loop maintaining bulk temperature below 60°C. The dissolver should be fabricated from carbon steel or 316L stainless steel in the low-temperature zone; heating surfaces above 80°C require nickel alloy trim because welded carbon steel in hot concentrated caustic service is vulnerable to stress-corrosion cracking. Solid bridging at the bag outlet can generate batch-to-batch variance in flake feed rate; on actual batching lines, use of a hopper with a mechanical stirrer and vibrator reduces bridging but requires dust extraction because broken flakes release residual fines. The viscosity of 50% NaOH at 20°C is approximately 80 mPa·s, which is substantially higher than water and should be accounted for in dosing pump sizing and line pressure drop calculations.
For ambient storage, sealed bags should be kept below 60% relative humidity. Caustic flakes are highly hygroscopic and begin to absorb atmospheric moisture when local RH exceeds the critical relative humidity of the surface film; for NaOH at 20°C this value is below 20%. Partial bags should be resealed or transferred to airtight hoppers. The material must not be stored with ammonium salts, cyanides, strong acids, or organic peroxides because contact may generate ammonia, hydrogen cyanide, or severe exothermic reactions. Contact with aluminium, magnesium, zinc, tin, brass, or bronze produces hydrogen gas; transfer lines should not contain these metals. Dry carbon steel storage is acceptable, but continuous wet contact above 50°C requires post-weld stress relief and may require a corrosion allowance.
In alumina refining, low-chloride caustic reduces chloride-related corrosion in heat exchangers and can reduce chloride salt carryover in precipitation circuits. Digestion liquor typically operates at 140–280°C and caustic concentrations equivalent to 140–250 g/L Na2O, with a NaOH-to-Al2O3 molar ratio in the range 1.5–3.0. Because Bayer circuits recycle liquor, chloride and carbonate impurities concentrate over time; the Grade I limit of NaCl ≤ 0.03% and Na2CO3 ≤ 0.5% provides a controlled makeup-alkali composition compared with lower grades. Published data specific to Xinjiang Tianye caustic soda flakes in Bayer operability is limited; plant trials are required to quantify scale inhibition and corrosion rates because bauxite gangue, lime, and liquor additives dominate fouling behavior more than the difference between Grade I and Grade II caustic at typical makeup rates.
Textile mercerizing uses strong caustic as a swelling agent for cotton; the process is typically run at 18–24°Bé, approximately 15–20% NaOH, and 15–20°C, with tension control to improve luster and dye uptake. In alkaline peroxide bleaching of chemical pulp, caustic flakes are dissolved to a stock solution and dosed to maintain pH 10.5–11.5; sodium hydroxide addition of 1.5–4.0 wt% on oven-dry pulp is common, but the exact dose is determined by peroxide stabilization and chelate performance. In soap and surfactant manufacture, the flakes are used to prepare 25–30% NaOH for saponification; the low NaCl and Fe2O3 limits reduce salt interference in soap grain formation. This industrial-grade material is not automatically compliant with FDA 21 CFR 173.310 or Food Chemicals Codex requirements; food-contact use requires dedicated certification.
Micropearls and flakes differ in handling because of particle geometry. Micropearls flow more freely in pneumatic conveying and dissolve faster due to higher surface-to-volume ratio; flakes have lower dust generation in manual bag charging but are more likely to bridge in hoppers and may require larger bag-breaking stations. On production-scale dissolver skids, batch-to-batch variance in flake thickness from drum flaking can shift total dissolution time; a thicker flake population dissolves more slowly under the same agitation and temperature. Table 2 summarizes general handling contrasts observed across solid and liquid alkali products.
| Handling or use property | Xinjiang Tianye caustic soda flakes | Typical 50% liquid NaOH | Typical micropearl solid |
|---|---|---|---|
| Water content by mass | Low, roughly 1% or less including impurities | Approximately 50% water | Low, comparable to flakes |
| Freezing behaviour | No aqueous freezing point; remains free-flowing if dry | Freezing plateau near 12°C | No aqueous freezing point; remains free-flowing if dry |
| Dust in manual charging | Moderate; fines from broken flakes | None | Lower dust than flakes, higher flowability |
| Dissolution rate in an agitated tank | Moderate; influenced by flake thickness and agitation | Immediate dilution as supplied | Faster than flakes at equal particle size distribution |
In alkaline cleaning and heavy-duty degreasing, flake-derived NaOH is made into 5–10% baths at 60–80°C for ferrous components; sodium hydroxide is not suitable for aluminium, zinc, tin, brass, or bronze parts because of vigorous hydrogen evolution and surface attack. In water treatment, a 0.05–1.0% solution is injected for pH elevation, but only after confirmation that the treatment stream does not contain soluble aluminium or generate precipitates that would clog dosing lines. The product’s low chloride and iron limits reduce addition of undesirable ions in closed-loop reuse systems, but on-site jar testing under actual water pH and hardness is required because precipitation of magnesium hydroxide can occur above pH 10.5.
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