Product Introduction

Sodium silicate powder, also known as instant powdered sodium silicate, instant water glass or powdered sodium metasilicate feedstock, has the general formula Na₂O·mSiO₂·nH₂O, where m is the modulus (molar ratio of SiO₂ to Na₂O) and n is the number of water of crystallization. It is produced from liquid sodium silicate (water glass) by modulus adjustment and spray drying. The product is an amorphous, uniform, white to off-white powder that retains all the properties and applications of liquid water glass while eliminating the inconvenience of transporting and storing liquids. Compared with mechanically milled anhydrous powder, the spray-dried grade offers faster dissolution, higher purity, narrower particle-size distribution and direct dry-blending compatibility with other powders, making it ideal for mechanized and automatic continuous feeding. Standard: GB/T 4209 Sodium silicate for industrial use (current edition GB/T 4209-2022). CAS No.: 1344-09-8.

Technical Characteristics

▪ Appearance & form: White to off-white amorphous powder, uniform particle size, free of mechanical impurities; apparent bulk density typically 0.30–0.80 g/mL.

▪ Solubility: Dissolves rapidly in water at room temperature; the aqueous solution is strongly alkaline (1% solution pH ≈ 11.5–12.5). Lower modulus dissolves faster; high-modulus grades need 60–80 ℃ warm water.

▪ Adjustable modulus: Modulus M can be customized from 1.6 to 3.4 by application; common commercial grades are 2.0, 2.3, 2.5, 2.85, 3.0 and 3.3.

▪ Colloidal & binding: Silicate anions polymerize into a 3-D network in solution; dehydration gives a siloxane gel with strong adhesion, high-temperature resistance and acid/alkali corrosion resistance.

▪ Physical stability: Non-combustible; strongly hygroscopic and prone to caking, gradually carbonized by atmospheric moisture and CO₂; must be sealed and stored dry.

▪ Dissolution-rate test: Time (seconds) required for essentially complete dissolution of a 1% addition under stirring at 30 ℃ — a key process index of this product.

Main Technical Parameters

The following are typical quality indexes of industrial instant powdered sodium silicate (representative grades; subject to the supply contract and certificate of analysis):

Note: The table above shows typical (representative) index ranges, which vary slightly by manufacturer and grade. Specific limits, impurity indexes and test methods shall follow GB/T 4209 for the applicable grade and the certificate of analysis. Modulus M is calculated as M = %SiO₂ ÷ %Na₂O × 1.032.

Requirements for Use

▪ Water quality & feeding: Use clean water at room temperature, or 60–80 ℃ warm water for higher-modulus grades. Add the powder slowly and uniformly into water under stirring; never add water to the powder to avoid lumping ("fish eyes").

▪ Solution concentration: Prepare the concentration required by the process (generally 1%–40%); high-modulus and high-concentration systems need heating with continued stirring. After complete dissolution, de-aerate, filter (recommend 100-mesh) and use.

▪ Compatibility: The solution is strongly alkaline; avoid direct contact with acids, acid salts, ammonium salts, heavy-metal ions and strong oxidants, which cause precipitation of silicic acid gel.

▪ Hardener: For binders, acid-resistant cements and grouting/strengthening, a hardener (sodium fluorosilicate Na₂SiF₆) is normally added at 12%–15%, adjusted with temperature, humidity, modulus and density (take the lower limit when temperature, modulus and density are high and low, respectively).

▪ Dry blending: Direct dry blending with other powders (cement, refractory aggregates, detergent base) is possible; a small trial is recommended to fix the ratio and setting time.

Precautions

▪ 1. Non-combustible but corrosive and strongly irritating; may cause burns. Wear dust mask, protective gloves and goggles; avoid dust inhalation and skin/eye contact.

▪ 2. After skin or eye contact, flush with plenty of running water for at least 15 minutes and seek medical attention if needed. If ingested, do not induce vomiting; dilute with water and seek medical help immediately.

▪ 3. Do not store or transport together with acids, acid substances, ammonium salts or oxidants. Store in a ventilated, dry warehouse away from damp floors and rain.

▪ 4. Strongly hygroscopic — caking reduces activity. Reseal tightly after opening and use promptly; keep warehouse relative humidity below 65%.

▪ 5. Prepare fresh solution on-site and use without prolonged standing. In acidic ground or hard-groundwater (high Ca²⁺/Mg²⁺) conditions, run a trial first to prevent premature gelation or line blockage.

▪ 6. Neutralize waste liquid to near neutral (pH ≈ 6–9) before discharge; dispose of the precipitate per local environmental regulations. Do not discharge directly into water bodies.

Packaging and Storage

▪ Packaging: Multi-ply composite kraft paper bag (or PP woven bag) with PE inner liner; common net weight 25 kg/bag. 50 kg/bag and FIBC/jumbo bag (1000 kg) are available on request.

▪ Storage conditions: Store in a cool, dry, well-ventilated warehouse. Keep sealed and dry, away from direct sunlight and heat sources. Stack off the floor and walls, avoiding excessive pile height.

▪ Shelf life: Stable for long-term storage when the package is intact and conditions are met; use first-in first-out and consume soon after opening.

▪ Transportation: Handle gently to avoid package damage. Do not load or transport together with acids or oxidants. Protect from rain and moisture in transit.

Scope of Application and Modulus-to-Application Mapping

The modulus M (n = molar ratio SiO₂/Na₂O) is the key parameter governing solubility, binding power, water resistance and gelation: the lower the modulus, the stronger the alkalinity, the faster the dissolution and setting, but the poorer the water resistance; the higher the modulus, the higher the solution viscosity and film/water resistance, but the more difficult the dissolution (high-modulus grades require warm or heated water). The selection rule is to match the modulus to the working condition, as detailed in the table below.

Selection guide: Detergent/cosmetic auxiliaries — prefer M 2.0–2.4; foundry, refractories and building materials — M 2.4–2.8; precision casting, ceramics and grouting — M 2.85–3.1; silica gel/silica source and oilfield plugging — M 3.2–3.4.