| HS Code | 461199 |
| Product Name | Caustic Soda Micropearls 99% Manufacturing Plant |
| Product Type | Turnkey chemical production plant |
| Main Output | Caustic Soda Micropearls 99% |
| Output Purity | 99% NaOH |
| Output Appearance | White spherical micropearls |
| Output Particle Size | 0.5 - 2.0 mm |
| Production Capacity | 50,000 metric tons per year |
| Manufacturing Process | Membrane-cell electrolysis, evaporation, and prilling |
| Primary Raw Materials | Sodium chloride brine, water, electricity |
| Core Equipment | Electrolyzer, evaporator, prilling tower, centrifuge, packaging line |
| Control System | Distributed Control System (DCS) |
| Utilities Required | Electricity, steam, cooling water, compressed air |
| Plant Area Requirement | 15,000 square meters approximately |
| Manpower Requirement | 30-40 operators per shift |
| Environmental Compliance | Zero liquid discharge with effluent treatment plant |
As an accredited Caustic Soda Micropearls 99% Manufacturing Plant factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Caustic Soda Micropearls 99% supplied in 25kg heat-sealed PE bags with outer woven PP bags, palletized and shrink-wrapped. |
| Container Loading (20′ FCL) | Loading 20′ FCL involves securing palletized caustic soda micropearls 99% in bags, ensuring proper weight distribution and safe, dry transport. |
| Shipping | Caustic soda micropearls ship in sealed, moisture-proof bags or bulk containers from the manufacturing plant. Strict handling protocols ensure safety—avoid water contact, use protective gear, and secure loading. Transport follows hazardous material regulations, with proper labeling and ventilation to prevent moisture absorption and maintain 99% purity. |
| Storage | Caustic soda micropearls must be stored in a cool, dry, well-ventilated area in sealed, moisture-proof containers or silos. Keep away from acids, moisture, and incompatible materials. Use corrosion-resistant flooring and secondary containment. Maintain clear labeling and proper handling equipment, with emergency showers and eyewash stations readily accessible. |
| Shelf Life | Shelf life is indefinite if stored sealed, dry, and moisture-free; avoid exposure to air to prevent caking and degradation. |
Alumina refineries operating high-temperature Bayer digestion units maintain caustic inventory within a narrow Na2O/Al2O3 molar ratio of 1.45–1.70 after red-mud separation. Digestion liquor is fortified with 99% sodium hydroxide micropearls to hold dissolved Na2O between 150 g/L and 300 g/L at 150–250°C; bauxite is pre-ground to a P80 of 0.150–0.300 mm and held in atmospheric pre-desilication at 95–105°C for 4–8 h before high-pressure digestion and multi-stage flash evaporation. Specific caustic consumption ranges from 40 kg to 150 kg NaOH per tonne of calcined alumina, with reactive silica in bauxite consuming 0.8–1.3 kg Na2O per kg reactive SiO2 through sodalite precipitation. Shell-and-tube heat exchangers in the digestion train exhibit heat transfer coefficient reduction of 20–40% over a campaign when reactive silica exceeds 5 wt% because sodalite and calcium aluminosilicate scale deposit on the tube side, forcing periodic acid descaling. Pressure vessels and digesters are specified under ASME BPVC Section VIII Division 1, while caustic receiving and storage for alumina producers commonly follow ANSI/AWWA B501-19; environmental management systems are operated to ISO 14001:2015. Downstream hydrate precipitation is conducted in air-lift or mechanically agitated precipitators with a seed charge of 300–800 g/L aluminum trihydrate, and the hydrolyzed product is calcined in rotary or gas suspension calciners. Terminal finished products include smelter-grade alumina, fine aluminum trihydrate, and specialty precipitated hydrates used in flame-retardant fillers.
In kraft pulping, the effective alkali charge on oven-dry softwood is set at 14–22 wt% Na2O with sulfidity 25–35%; hardwood lines typically operate at the lower bound of the charge range. White liquor is maintained at 90–120 g/L active alkali as Na2O, and liquor-to-wood ratio is 3.5:1–4.5:1. 99% micropearls are dissolved to 50% NaOH before use in recausticizing and are not dry-dosed into the digester; this prevents localized exotherm and fiber degradation at the feed point. Continuous hydraulic digesters run softwood at an H-factor of 1,600–2,200, with maximum cooking temperature 160–170°C and blow-line kappa controlled to 25–30. Oxygen delignification is carried out at 80–100°C under 500–700 kPa oxygen partial pressure, removing 40–50% of residual kappa before chlorine dioxide and peroxide bleaching. Brownstock washing uses countercurrent washing lines with a dilution factor of 1.5–2.5 m³ per tonne pulp. Pulp quality is tested against ISO 302:2015 for kappa number and ISO 1762:2019 for residue on ignition, while mill environmental performance falls under Directive 2010/75/EU best available techniques for pulp and paper. Production-scale data indicate that a drop in active alkali below the target window increases screen room rejects above 0.5% on dry wood mass. Terminal product forms include bleached and unbleached kraft pulp, linerboard, sack paper, and dissolving pulp for cellulose derivatives.
Continuous saponification lines running tallow, palm stearin, and coconut oil blends are dosed with 99% caustic soda micropearls after the fat phase has been heated to 80–95°C in plate-and-frame heat exchangers. The alkali requirement is calculated from ISO 3657:2020 saponification value; for a fat with saponification value 190–205 mg KOH/g, fresh micropearl demand is 136.8–147.6 g per kg fat at 99% NaOH content. The 50% caustic stream and molten fat are mixed under high-shear agitation in a closed saponification kettle with neat soap recycle held at 30–50% of feed mass to control phase inversion. The neat soap phase is then separated from spent lye and glycerin through countercurrent extraction; sweet water from separation is concentrated in evaporators to 80–85% crude glycerin. Vacuum spray drying follows to reduce moisture to 10–13% before noodling and pressing. Overdosing caustic by more than 2% above stoichiometric requirement shifts the neat soap phase into a soft, high-free-alkali gel that clogs vacuum dryers; finished soap free caustic is therefore controlled below 0.1% NaOH to comply with Regulation (EC) No 648/2004 detergent safety requirements and REACH (EC) No 1907/2006 substance restrictions. Terminal finished products include soap noodles, toilet soap base, laundry soap flakes, and saponified oleochemical intermediates.
Packed-tower chlorine scrubbing uses a circulating 20% NaOH solution generated from micropearls, with stoichiometric demand of 1.128 kg NaOH per kg Cl2; the equivalent feed of 99% micropearls is 1.139 kg per kg Cl2. Product residual alkali is held at 0.5–1.0% NaOH by mass to maintain pH 12.5. The absorber is operated at 20–30°C because chlorate formation accelerates above 35°C; cooling is supplied by an external plate heat exchanger on the recycle loop, and the exothermic reaction enthalpy is approximately −103 kJ/mol Cl2. A falling-film absorber is substituted when chlorine partial pressure is high, and the caustic circulation ratio is interlocked with chlorine gas flow to hold outlet chlorine below 1 ppm. Sodium hypochlorite generated in this configuration conforms to EN 901:2013 for drinking water chemicals when raw materials and dilution water meet the same standard. The process utilizes structured ceramic packing or corrosion-resistant polymer internals. Terminal product type is sodium hypochlorite solution at 10–15% available chlorine, used in municipal disinfection, membrane cleaning, and industrial oxidative bleaching.
The mercerizing range is operated with a chainless clip width of 1800–2200 mm and a fabric speed of 40–80 m/min depending on woven or knit construction. 99% micropearls are dissolved to an 18–24% NaOH working solution and maintained at 15–25°C to maximize cellulose I-to-cellulose II conversion under tension; scouring ahead of mercerization uses 1–4% NaOH on weight of fabric. Fabric dwell in the saturator is held at 35–60 s, followed by hot water displacement at 60–90°C and neutralization with acetic acid at 0.5–1.5 g/L. Textile compliance is verified under ZDHC MRSL v3.1 and OEKO-TEX Standard 100, with tensile properties measured according to ISO 13934-1:2013 for woven fabrics. Production-scale tensile data indicate strength increase of 10–20% after mercerization due to fiber untwisting and improved longitudinal orientation; however, published data for specific single-jersey knit behavior at low applied tension is limited. Spent caustic is recovered through evaporation to 30–40% NaOH and returned to the saturator after filtration. Terminal finished products include mercerized cotton yarn, high-luster shirting, denim, and mercerized knitwear for home textile applications.
Refinery caustic wash systems treating LPG and light naphtha are configured as countercurrent extraction columns with external circulation coolers. The caustic solution is prepared at 5–15% NaOH from micropearls; H2S prewash uses the lower concentration, while Merox extraction for mercaptan oxidation uses 10–15% NaOH with sulfonated cobalt phthalocyanine catalyst. Treat rates are typically 0.1–0.5 vol% of hydrocarbon feed, and LPG contactor operation is maintained at 30–50°C and 1.0–1.8 MPa to keep the blend in liquid phase. Spent caustic, often carrying sodium sulfide above 5 wt%, is routed to a dedicated oxidation unit operating at 70–90°C and 0.7–1.0 MPa with air injection to convert sulfides to thiosulfate, rather than being mixed with acid waste streams. Treated LPG is sampled for H2S content by ASTM D7621-17 and for total sulfur by ISO 20846:2019, with typical specification limits below 10 ppm H2S and 30 ppm total sulfur. Terminal finished products include low-sulfur LPG, gasoline blendstock, and jet fuel components after downstream sweetening.
Potable water stations apply 99% micropearls as a 0.1–10 mg/L NaOH solution to hold distribution pH within 7.0–8.0 under EN 896:2012 and ANSI/AWWA B501-19, with static mixer injection into a clearwell to produce stabilized drinking water; boiler feed demineralization units use 4–8% NaOH for anion resin regeneration at 35–50°C, yielding demineralized water with conductivity below 5 µS/cm.
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Caustic Soda Micropearls 99% Manufacturing Plant is supplied as a continuous process package for conversion of membrane-cell sodium hydroxide liquor into anhydrous spherical micropearls. The product envelope is established at NaOH ≥ 99.0 wt%, with carbonate, chloride, and iron limits fixed in the contract datasheet and typically benchmarked to GB/T 209-2018 or EN 896:2012 for water-treatment destinations. Model designations follow the format CP-CSM-XX/99, where XX denotes nameplate output in thousands of tonnes per year on a 100% NaOH basis; the reference unit CP-CSM-45/99 corresponds to a 45,000 t/a installation. The plant comprises falling-film pre-evaporation, final high-concentration finishing in nickel alloy, melt filtration, prilling, cooling, classification, and dry packaging. Carbon steel is limited to low-temperature, low-concentration upstream sections; final wetted parts are specified in nickel 200/201 or equivalent low-carbon nickel alloy because anhydrous caustic at processing temperature attacks stainless steel and titanium. Pressure-retaining equipment is supplied under ASME BPVC Section VIII Division 1 or PED 2014/68/EU according to the installation jurisdiction, and the continuous runtime basis is 8,000 h/a.
The plant output is specified around the micropearl form rather than flake or block form. A micropearl is defined by controlled particle geometry and a narrow size distribution; the production line is arranged to deliver ≥92 wt% between 0.5 mm and 1.2 mm, with mass median diameter between 0.6 mm and 0.9 mm. Chemical purity is governed by upstream liquor polishing and by the material selection of the final evaporation train, not only by the solidification step. The design quality envelope for a standard export-grade micropearl is given below.
| Parameter | Typical 99% micropearl design envelope | Reference method or standard |
|---|---|---|
| Sodium hydroxide as NaOH | ≥99.0 wt% | ASTM E291-18; GB/T 209-2018 solid grade |
| Sodium carbonate as Na2CO3 | ≤0.50 wt% | ASTM E291-18 carbonate determination |
| Sodium chloride as NaCl | ≤0.05 wt% | ASTM E291-18 or ion chromatography after dissolution |
| Iron as Fe | ≤0.0005 wt% | ICP-OES after dilution in ultrapure water |
| Particle size distribution | ≥92 wt% between 0.5 mm and 1.2 mm; d50 0.6–0.9 mm | ISO 3310-1:2016 screening |
| Loose bulk density | 1.10–1.30 g/cm³ | in-house pour density, 1 L cylinder, 20°C, 3 replicates |
| Moisture / volatile content | ≤0.3 wt% as loss on heating | in-house method at 250°C to constant mass |
If the micropearls are destined for water-treatment use, the product is additionally assessed against the applicable purity clauses of EN 896:2012. For industrial customers in Asia, GB/T 209-2018 grade limits commonly control acceptance. Published data for this specific configuration is limited; final limits are fixed in the plant performance guarantee and reflected in the analyzer schedule.
The pre-evaporation train receives clarified sodium hydroxide liquor at 32–33 wt% NaOH and 60–80°C. Multiple-effect falling-film evaporators, normally specified in 316L or duplex stainless steel for the first effects, concentrate the liquor to approximately 50 wt% NaOH before transfer to the high-concentration section. The finisher uses forced-circulation or thin-film equipment with nickel 200 heat-transfer surfaces; nickel is required because high-temperature caustic destroys the passive film on stainless steel and causes rapid erosion-corrosion in titanium. The final stage removes residual water to produce an anhydrous melt at 330–370°C. Low-carbon nickel 201 is specified for components operating above 315°C to limit intergranular attack. Melt filtration upstream of prilling removes insoluble particulates that would otherwise cause nozzle plugging and off-spec oversize. The filtered melt is pumped to a prilling tower; rotary nozzles or spray disks generate droplets that are cooled by countercurrent air with pressure dew point ≤ -40°C according to ISO 8573-1:2010 Class 2 or better. The tower discharge is screened on a two-deck vibratory classifier; the lower deck rejects undersize dust, and the upper deck removes oversized agglomerates. Off-spec material is re-dissolved and returned to the upstream liquor circuit. Dust-laden air from the classification and conveying line passes through bag filters with high-efficiency media and is discharged only after meeting the plant emission permit.
The molten-handling section is operated under a low-carbon-dioxide environment to limit sodium carbonate formation; nitrogen or dried air with CO₂ < 50 ppmv is used for melt storage and prilling tower air. Solid micropearls are cooled below 50°C before packaging. Automatic bagging machines fill 25 kg polyethylene-lined paper bags or 500–1,000 kg flexible intermediate bulk containers with internal liners. Filled packages are palletized and stretch-wrapped in a dry area at ≤30% RH and 15–25°C. A central distributed control system monitors caustic concentration, melt temperature, prilling air dew point, and classifier load; safety instrumented functions are designed according to IEC 61511 for high-temperature shutdown and seal gas failure.
Micropearls are used in dry sodium hydroxide dosing lines where flowability, dust control, and consistent particle-size distribution determine metering accuracy. Compared with flakes, micropearls have higher loose bulk density, fewer irregular edges, and lower dust generation during conveying. Compared with conventional larger pearls, the smaller mean diameter increases the specific surface area available for dissolution. However, the same surface area increases the rate of moisture and carbon dioxide pickup if the product is exposed to ambient air; the dosing line therefore requires dry air purging or nitrogen blanketing. The table below summarizes the principal handling differences among micropearls, flakes, and larger pearls.
| Handling property | Micropearls 99% | Flakes 99% | Standard pearls 99% |
|---|---|---|---|
| Loose bulk density | 1.10–1.30 g/cm³ | 0.80–1.00 g/cm³ | 1.05–1.25 g/cm³ |
| Particle geometry | spherical, 0.5–1.2 mm | irregular platelet, 2–10 mm major axis | spherical, 1.0–2.5 mm |
| Flow classification | free-flowing; suitable for loss-in-weight screw feeders | cohesive; prone to arching and ratholing | moderate; requires a wider hopper outlet |
| Dust release in dense-phase conveying | low | high | moderate |
| Dissolution surface | higher surface area per unit mass than larger pearls; lower dust than flakes | high exposed edge area; rapid initial dissolution but uneven metering | lower surface area per unit mass; slower dissolution under identical agitation |
Flow classification should be verified by ASTM D6128-16 shear cell measurements on the specific batch because bulk solids flow is a function of consolidation stress and moisture. Hopper outlet dimensions and feeder screw geometry must be derived from measured flow properties rather than analogy to other caustic soda forms. Automated dosing systems for micropearls are typically specified for a mass setpoint deviation below ±2% over a dispensing cycle; the spherical form reduces segregation in the hopper and improves cut-off at the feeder screw. Published data for this specific configuration is limited.
Dissolution of 99% micropearls is strongly exothermic. A suitable dissolving skid adds solid caustic to water under agitation, not water to a dry bed. The heat of solution of anhydrous sodium hydroxide is approximately -44.5 kJ/mol, corresponding to approximately 1.1 MJ/kg of NaOH. A temperature control loop with cooling water flow linked to the dissolving tank protects against localized boiling and splatter. Materials for the dissolving tank and recirculation piping are selected for the maximum solution temperature at the target concentration. Emergency shower and eyewash equipment is placed near bag dumping and drum handling stations.
In sodium hypochlorite generation, the micropearls are dissolved to produce a 20–30 wt% NaOH solution, which is then reacted with chlorine. The final salt content is controlled because chloride already present in the caustic reduces chlorate formation and impacts product stability; the low chloride specification of ≤0.05 wt% is therefore relevant for hypochlorite quality. In soap and detergent saponification, dry micropearls are metered into molten fat or oil neutralization stages; the spherical geometry reduces bridging in loss-in-weight feeders and supports uniform saponification rate. In wastewater treatment, micropearls are dissolved in mixing tanks to prepare 10–50 wt% solutions for pH adjustment; the dissolution skid is designed to prevent localized overconcentration.
Carbonate pickup in anhydrous caustic soda is a surface-driven process; moisture film formation accelerates the reaction with atmospheric carbon dioxide. The plant therefore uses dried air with pressure dew point ≤ -40°C and CO₂ < 50 ppmv for prilling and conveying air. The packaging area is maintained at ≤30% RH and 15–25°C; silos are inerted with nitrogen where storage exceeds 72 h. The handling system design includes hopper outlets sized from measured wall friction angles on the actual moisture-conditioned product. Carbonate accumulation in recycle streams is limited by purging a small slipstream from the re-dissolution loop and replacing it with fresh membrane-cell liquor. The plant control system logs dew point, carbon dioxide, and temperature in the prilling air supply; deviations beyond the operating window automatically divert product to the off-spec bin.
The final melt piping and prilling circuit avoid aluminosilicate insulation at flanges where caustic splash may attack the insulation. Bag filters handling caustic dust are fitted with PTFE membrane media and 316L or higher alloy cages; scrubbed liquor is returned to the dilution tank. Sodium hydroxide emissions from the stack are controlled to the site permit limit, and continuous analyzers are installed for caustic mist where local regulations require it. The plant is also arranged to contain spills from the bagging area and to prevent contact of molten caustic with water, aluminum, zinc, tin, or chlorinated solvents.
Because anhydrous caustic is corrosive to glass and silica, the dissolution and process water should be demineralized or at least low-hardness water to avoid precipitation of calcium and magnesium hydroxides that can foul downstream metering pumps. Process water hardness above 50 mg/L as CaCO3 can accelerate scale formation in the dissolution loop; an ion-exchange or reverse osmosis polisher is recommended. The design package specifies instrument air quality for valve actuators and prilling air quality for product contact. At ambient relative humidity above 60%, pre-drying of packaging-area make-up air is required to prevent bag surface condensation.
Model designations follow the format CP-CSM-XX/99, where XX is the nominal annual output in thousands of tonnes per year. Standard reference configurations are built around 15,000 t/a, 45,000 t/a, and 120,000 t/a nameplate capacities. The 15,000 t/a unit is typically a single finishing effect with one prilling tower cell; the 45,000 t/a unit uses two parallel high-concentration finishers and a single multi-nozzle prilling tower; the 120,000 t/a unit uses four parallel finishers and two prilling towers or one large-diameter tower with multiple nozzle rows. Utility consumption is site-specific because feed liquor concentration, steam pressure, and cooling water supply temperature influence evaporator economy; published data for this specific configuration is limited. A basic engineering package includes heat and material balances, PFDs, P&IDs, equipment datasheets, and the performance guarantee for the selected capacity.
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