Potassium Carbonate: A Multi-Sector Key Raw Material for Agriculture, Food, and Industry

Basic Information

• Chemical Formula: K₂CO₃

• Molecular Weight: 138.206

• CAS Number: 584-08-7

• EINECS Number: 209-529-3

• Melting Point: 891 °C

• Solubility: Easily soluble in water

• Density: 2.43 g/cm³

• Appearance: White crystalline powder

• Hazard Symbol: Xn (Harmful)

• Risk Phrases:

  • R22 (Harmful if swallowed)

  • R36/37/38 (Irritating to eyes, respiratory system, and skin)

• Safety Phrases:

  • S26 (In case of contact with eyes, rinse immediately with plenty of water and seek medical advice)

  • S36 (Wear suitable protective clothing)

  • S37/39 (Wear suitable gloves and eye/face protection)

• UN Number: 3262

Physical and Chemical Properties

Potassium carbonate appears as a white granular or crystalline powder. Its core characteristics include:

• Solubility: Highly soluble in water, yielding an alkaline solution; insoluble in ethanol, acetone, and ether. This property makes it particularly suitable for water-based applications such as fertigation and industrial solution preparation.

• Hygroscopicity: Strongly hygroscopic, absorbing CO₂ and moisture from air to gradually form potassium bicarbonate. Requires sealed packaging during storage and transport.

• Hydrates: Exists in monohydrate, dihydrate, and trihydrate forms; loses water of crystallization at 100 °C and shows good thermal stability.

• pH Value: A 10% aqueous solution has a pH of ~11.6, making it effective both as a soil conditioner and as a neutralizing agent in food and industrial processes.

Production Methods

Potassium carbonate can be produced via several methods:

1. Plant Ash Method (historical, low purity, largely abandoned except in remote regions or traditional crafts).

   
   

2. LeBlanc Process (18th century industrial process, energy-intensive, now obsolete).

   
   

3. Electrolytic Method (mainstream, large-scale production):

   • Uses potassium chloride as raw material, electrolyzed to potassium hydroxide solution, then carbonated with CO₂ to form potassium bicarbonate and finally calcined.

   • Advantages: Abundant raw materials, high yield, no “three wastes,” scalable.

   • Limitation: High power consumption.

     
     

4. Ion-Exchange Method (flexible, small-scale, high-purity production):

   • Uses cation-exchange resin and ammonium bicarbonate to produce potassium bicarbonate solution, then crystallized and calcined.

   • Advantages: High product quality, lower energy consumption.

   • Limitation: Resin replacement costs, smaller capacity.

Comparison of Mainstream Methods:

Dimension	Electrolytic Method	Ion-Exchange Method
Raw Materials	KCl, electricity, CO₂	KCl, ammonium bicarbonate, resin
Product Purity (Industrial)	99–99.5%	99.5–99.8%
K Conversion Rate	≥95%	≥92%
Energy Use (tce/ton)	~1.2	~0.6
Annual Capacity/Line	100,000–300,000 tons	5,000–20,000 tons
Investment	High (~150M RMB/100k t)	Low (~20M RMB/10k t)
Environmental Aspects	No “three wastes,” Cl₂ recyclable	Some ammonium wastewater
Best Fit	Large-scale, power-rich	Small-scale, ultra-high purity

Applications

Agriculture

• Problem Addressed: Acidification of soils due to dominance of acidic fertilizers (urea, MAP, MKP, ammonium sulfate, etc.), coupled with limited alkaline fertilizer options.

  
  

• Core Advantages of Potassium Carbonate:

  1. High purity for water-soluble fertilizers – 100% soluble K⁺, no chloride or sulfate, avoids soil salinization, improves nutrient uptake.

  2. Soil pH regulation – Neutralizes excess acidity, restores soil structure, maintains optimal crop pH (6.0–7.5).

  3. CO₂ release for photosynthesis – Natural CO₂ supplementation in greenhouses, reducing labor and amendment costs.

Practical Applications:

Scenario	Condition	Method	Recommended Dosage
Acid soil improvement	pH < 6.0 farmland/greenhouses	Spray/drip irrigation	30 kg/ha
Alkali-loving crops/flowers	Orchids, carnations, etc.	Spray/drip irrigation	30 kg/ha

Animal Nutrition

• Nutritional Value:

  • Provides potassium (essential for osmotic pressure, nerve conduction, muscle function).

  • Carbonate anion contributes to acid-base buffering.

    
    

• Feeding Effects:

  • Corrects potassium deficiency (weakness, poor growth, arrhythmias).

  • Mitigates heat stress by replacing lost K⁺ in hot conditions.

  • Improves DCAD (dietary cation-anion difference) in dairy cattle, preventing acidosis.

  
  

• Dosage:

  • In complete feed: 0.1–0.3% of diet.

  • Dairy cow: 100–150 g/day (avoid excess to prevent Mg deficiency or K toxicity).

Food Industry

• Used as acidity regulator, neutralizer, and alkaline agent in noodles, bakery, and dairy.

• Compared with sodium carbonate:

  • Produces crisper noodles with better mouthfeel.

  • Substitutes Na⁺ with K⁺, beneficial for cardiovascular health (hypertension prevention).

• Typical usage: 0.1–2% in flour-based products.

Other Industrial Uses

• Glass: Improves transparency and stability in optical glass, bulbs, display tubes.

• Electronics/Electroplating: Used as pH regulator and high-purity reagent.

• Pharmaceuticals/Dyes: Intermediate in antibiotics, dye auxiliaries.

• Others: CO₂ absorbent, fire extinguisher powders, rubber antioxidant, fertilizer gas scrubbing.

Global Market Overview

• Market Size:

  • Global potassium carbonate market reached record highs in 2024, growing 3–5% annually despite raw material and logistics challenges.

    
    

• Regional Distribution (2024):

  • Asia (55–60%): Driven by China/India agriculture and industrial growth.

  • Europe (20–25%): High demand for high-purity products in food/pharma; strict environmental standards.

  • North America (15–20%): Balanced agricultural and industrial demand; relies partly on imports.

Future Trends (2024–2032):

• Asia expansion: Market share >65% by 2032, fueled by agricultural modernization and industrial growth.

• Europe/US: Slight share decline due to slower growth and offshoring of production.

• Shift to high-purity products: Demand for ≥99.5% purity grows at 8–10% annually, far above ordinary industrial grades (2–3%).

Conclusion

Potassium carbonate stands as a multi-functional, cross-sector essential raw material, with advantages of alkalinity, high potassium content, and low impurities.

• Production: Electrolytic and ion-exchange processes dominate, balancing large-scale and high-purity needs.

• Applications: From correcting soil acidification in agriculture, supplementing potassium in animal feed, enhancing food quality, to enabling glass, electronics, and pharmaceuticals.

• Market: Global expansion led by Asia, with high-purity grades becoming the main competitive focus.

  
  

With ongoing agricultural modernization, industrial upgrading, and health-oriented consumption trends, potassium carbonate is set to expand its role as a cornerstone material across industries.