OVERVIEW
NP 18–46–0 compound fertilizer is a high-phosphorus, nitrogen–phosphorus fertilizer, commonly known as DAP-type fertilizer. It contains:
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18% Nitrogen (N)
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46% Phosphorus (P₂O₅)
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0% Potassium (K₂O)
This fertilizer is widely used for basal application, especially during early crop establishment, due to its excellent phosphorus availability and nitrogen support.
IMPORTANCE OF NP 18–46–0 FERTILIZERS
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Promotes strong root development
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Enhances early plant vigor
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Improves flowering and seed formation
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Provides fast-acting, water-soluble phosphorus
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Suitable for a wide range of crops and soil types
RAW MATERIALS USED IN NP 18–46–0 PRODUCTION
PHOSPHORUS SOURCES
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Phosphoric acid
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Phosphate rock (after acidulation)
NITROGEN SOURCES
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Anhydrous ammonia
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Aqueous ammonia
AUXILIARY MATERIALS
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Process water
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Granulation aids
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Anti-caking agents
PRODUCTION METHODS OF NP 18–46–0 COMPOUND FERTILIZERS
1. AMMONIATION–GRANULATION METHOD (MOST COMMON)
PROCESS DESCRIPTION
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Phosphoric acid is neutralized with ammonia
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Ammonium phosphate slurry is formed
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The slurry is sprayed onto recycled fines in a granulator
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Granules are built up by layering and agglomeration
MAIN STEPS
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Acid–ammonia neutralization
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Slurry preparation
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Granulation (drum or pan granulator)
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Drying
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Screening
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Cooling
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Coating and packaging
ADVANTAGES
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Uniform nutrient distribution in each granule
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High chemical purity
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Excellent granule strength
2. SLURRY GRANULATION PROCESS
PROCESS DESCRIPTION
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Concentrated ammonium phosphate slurry is directly fed into the granulator
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Granulation occurs through controlled moisture and temperature
KEY FEATURES
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High production efficiency
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Stable granule size control
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Suitable for large-scale industrial plants
3. PIPE REACTOR TECHNOLOGY
PROCESS DESCRIPTION
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Ammonia and phosphoric acid react inside a pipe reactor
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High-temperature reaction produces ammonium phosphate melt
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Melt is discharged directly into the granulator
ADVANTAGES
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Very high conversion efficiency
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Lower energy consumption
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Reduced dust formation
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Improved granule hardness
4. BULK BLENDING + RE-GRANULATION (ALTERNATIVE METHOD)
PROCESS DESCRIPTION
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Pre-produced ammonium phosphate materials are blended
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Moisture, steam, or binders are added
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Mixture is re-granulated and dried
LIMITATIONS
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Less chemical uniformity compared to true compound methods
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Mainly used where integrated chemical plants are not available
DRYING, SCREENING, AND COOLING
DRYING
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Reduces moisture to improve storage stability
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Prevents caking and microbial degradation
SCREENING
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Ensures uniform granule size
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Oversize crushed and recycled
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Fines returned to granulator
COOLING
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Improves granule hardness
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Reduces dust formation
QUALITY CONTROL PARAMETERS
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Total nitrogen content
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Available phosphorus (P₂O₅)
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Moisture content
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Granule size distribution
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Bulk density
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Crush strength
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Caking tendency
APPLICATION AREAS OF NP 18–46–0
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Cereals (wheat, maize, rice)
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Oilseeds
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Legumes
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Vegetables
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Fruit orchards (basal application)
ADVANTAGES OF NP 18–46–0 COMPOUND FERTILIZER
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High phosphorus availability
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Excellent starter fertilizer
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Low application rate due to high nutrient concentration
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Compatible with most soil types
SUMMARY
NP 18–46–0 compound fertilizers are produced mainly through ammoniation–granulation and pipe reactor technologies, ensuring high nutrient concentration and uniform granules. These fertilizers are essential for early plant development and are widely used as basal fertilizers in modern agriculture.
