Phosphoric acid is one of the most widely used industrial chemicals in the world. It plays a vital role in fertilizers, food processing, pharmaceuticals, detergents, metal treatments, and high-tech industries such as semiconductors and batteries. Although it is a common product, the methods used to produce phosphoric acid differ greatly in terms of purity, cost, environmental impact, and raw material requirements.
In the global chemical industry, three major processes are used to manufacture phosphoric acid:
The Thermal Electric Furnace Process
The Wet-Process Phosphoric Acid Technology (Sulfuric Acid or Hydrochloric Acid Route)
The New Thermal Phosphoric Acid Production Technology
Thermal Electric Furnace Process - Producing the Highest Purity Phosphoric Acid
The thermal electric furnace process is the oldest and most refined method for producing high-purity phosphoric acid. Unlike the wet process, which relies on direct acid digestion of phosphate ores, the thermal route produces phosphoric acid through the intermediate production of elemental yellow phosphorus. This process is energy-intensive but produces exceptionally pure acid, making it valuable for specialty and high-end industries.
Product Quality and Purity Levels
Thermal phosphoric acid is known for its extremely low impurity content, including:
Very low heavy metal concentrations
Very low fluoride levels
No sulfate contamination
Exceptional clarity and color stability
Its main product categories include:
High-purity industrial-grade phosphoric acid
Food-grade phosphoric acid
Electronic-grade phosphoric acid
Ultra-pure phosphoric acid for semiconductors
The wet process simply cannot reach this purity without extensive and costly purification.
Key Applications of Thermal-Grade Phosphoric Acid
Because of its purity, thermal phosphoric acid is widely used in:
Food additives (acidulants, beverage ingredients)
Pharmaceutical manufacturing
Semiconductor etching and cleaning
High-performance lithium battery materials
Precision electronic chemicals
Optical materials
These applications require extremely low levels of contaminants that wet-process acid cannot meet.
Advantages and Disadvantages of the Thermal Process
Advantages:
Highest purity phosphoric acid
No phosphogypsum waste
Valuable by-products (ferrophosphorus)
Ideal for high-end industries
Disadvantages:
High electricity consumption
Requires high-grade phosphate rock
Higher production cost compared to wet process
Although expensive, the thermal process remains indispensable in high-value industries requiring maximum purity.
Wet-Process Phosphoric Acid Production - The Mainstream Method for Fertilizer and Industrial Use
The wet process is the most widely used method globally, accounting for more than 85% of world phosphoric acid production. It is generally considered the most economical and best suited for manufacturing fertilizers and large-volume industrial chemicals.
There are two major wet-process variants:
Sulfuric acid process (dominant method)
Hydrochloric acid process (less common but useful for special ores)
2.3 Products Produced by the Wet Process
The wet process is designed for large-scale industrial production, mainly used to manufacture:
Industrial-grade phosphoric acid
Phosphate fertilizers (DAP, MAP, TSP, SSP)
Feed-grade phosphates
Sodium and potassium phosphates
Detergent phosphates
Water treatment chemicals
This makes the wet process the backbone of the global fertilizer industry.
Advantages and Limitations
Advantages:
Lower cost than the thermal method
Well-suited for mass production
Flexible concentration levels
Compatible with a wide range of industries
Limitations:
Generates large quantities of phosphogypsum
Higher impurity levels (fluoride, heavy metals, sulfate)
Not suitable for high-purity or electronic applications
Requires land, storage, and environmental management for gypsum stacks
Because of these constraints, wet-process acid often requires upgrading when purity levels are critical.
New Thermal Phosphoric Acid Production Technology
The new generation of thermal phosphoric acid technology represents a significant advancement in the industry. Recent innovations make it possible to use phosphate rock with P₂O₅ content below 20%, which was previously unsuitable for thermal production.
This breakthrough changes the economics and resource structure of thermal phosphoric acid production.
3.1 Why This New Technology Matters
Traditional thermal plants require high-grade phosphate rock, typically with P₂O₅ content above 30%, to ensure efficient reduction reactions. Such high-grade ores are expensive and increasingly scarce.
The new thermal technology uses advanced furnace designs, modified feed structures, and optimized reaction control, allowing the use of:
Medium-grade phosphate rock
Low-grade phosphate rock (below 20% P₂O₅)
Complex ores with high impurities
Ores unsuitable for wet-process digestion
This dramatically reduces raw material costs and expands resource availability.
3.2 Key Features of the New Technology
The new generation of thermal phosphoric acid production technology represents a major upgrade over traditional electric furnace systems. It integrates advancements in furnace efficiency, reactor design, impurity control, refractory engineering, and digital automation. Together, these innovations allow stable, high-purity phosphoric acid production even when using low-grade or complex phosphate ores.
Improved Furnace Energy Efficiency
Modern thermal furnaces are designed with significantly higher energy utilization rates. This is achieved through advanced electrode layouts, optimized heat transfer mechanisms, and intelligent furnace temperature management systems. New insulation materials help reduce heat loss, while upgraded power supply systems ensure stable electrical input with minimal fluctuations. As a result, plants can achieve:
Lower electricity consumption per ton of P₂O₅
More stable furnace operation
Reduced overheating risks
Lower overall energy cost
Optimized Reactor Design to Enhance Phosphorus Volatilization
In traditional thermal processes, incomplete volatilization of elemental phosphorus often leads to material loss and lower production efficiency. The new technology addresses this through:
Streamlined reactor geometry
Enhanced airflow distribution
Better reaction zone temperature control
Improved residence time of feed materials
Controlled oxygen injection systems
These improvements help maximize phosphorus volatilization rates, ensuring that a higher percentage of phosphorus is successfully captured and converted into phosphoric acid. This results in both higher yield and lower raw material waste.
Advanced Impurity Control and Purification Systems
One of the most impressive features of the new thermal process is its advanced impurity control capability. Traditional furnaces struggle with impurities such as iron, magnesium, silica, or organic residues, especially when processing lower-grade ores. The improved technology introduces:
Multi-stage gas scrubbing systems
High-efficiency dust removal and particle separation
Upgraded condensation units to prevent impurity carryover
Controlled oxidation to minimize heavy metal contamination
These systems ensure that impurities are captured early in the process, delivering exceptionally pure phosphorus gas for oxidation. The result is a more stable and high-quality thermal phosphoric acid product suitable for food-grade, pharmaceutical-grade, and electronic applications.
High-Performance Refractory and Insulation Materials
Furnace refractory life has historically been a major bottleneck for thermal phosphoric acid production. New-generation furnaces now use:
Ultra-high temperature–resistant refractories
Improved anti-corrosion lining materials
Long-lasting insulation bricks
Multi-layer protective barriers
Advanced cooling system integration
These features significantly reduce refractory erosion, swelling, and chemical attack. As a result, furnace campaign life is extended, maintenance frequency is reduced, and the risk of unexpected shutdowns is minimized. Longer refractory life directly contributes to lower operating expenses and increased plant uptime.
Automated Process Monitoring and Digital Plant Control
Digitalization is one of the defining characteristics of the new thermal production technology. Modern plants integrate:
Real-time temperature and pressure monitoring
Continuous gas composition analysis
Smart feed rate and oxygen flow control
Computer-integrated furnace management systems
Cloud-based plant diagnostics and early-warning systems
These tools allow precise process control, ensuring consistent production quality and operational safety. Advanced algorithms can predict furnace performance, detect abnormalities early, and adjust operational parameters automatically. This reduces operator workload and minimizes human error. With digital control, plants can run more reliably and respond dynamically to variations in ore quality or energy supply.
Efficient Use of Low-Grade Ores Due to Integrated System Upgrades
The combined effect of these innovations-higher energy efficiency, optimized volatilization, impurity management, improved refractory performance, and digital automation-enables the system to handle low-grade phosphate ore effectively. Even ores with less than 20% P₂O₅ can be processed economically. This technological leap helps:
Lower raw material cost
Expand usable ore resources
Reduce dependency on premium-grade phosphate
Improve long-term sustainability of the phosphate industry
3.3 Environmental and Economic Benefit
The process delivers strong advantages:
No phosphogypsum waste
Lower operational carbon footprint when paired with renewable electricity
Higher equipment life due to improved furnace materials
Better raw material utilization
Valuable by-products such as ferrophosphorus
Consistent high purity suitable for food, pharmaceutical, and electronic industries
Comparison of the Three Major Production Technologies
| Technology | Purity | Main By-Product | Raw Material Demand | Main Applications | Cost Level |
|---|---|---|---|---|---|
| Thermal Electric Furnace | Highest (food, electronic grade) | Ferrophosphorus | High-grade ore | High-tech, food, pharmaceuticals | High |
| Wet-Process Sulfuric/HCl | Medium | Phosphogypsum | Medium-to-high grade ore | Fertilizers, detergents, industrial chemicals | Low |
| New Thermal Technology | Very high | Valuable metallic by-products | Low-grade ore (<20% P₂O₅) | Food, industrial, electronic | Medium |
Which Process Should a Producer Choose?
The choice depends on market positioning, raw material availability, investment scale, and purity requirements.
Choose Thermal Electric Furnace If:
You target food, pharma, semiconductor, or battery industries
Ultra-high purity is essential
Electricity is affordable or renewable
Choose Wet Process If:
You focus on fertilizers or general industrial chemicals
You require low production cost
Large output capacity is needed
Choose the New Thermal Technology If:
You want high purity without expensive ore
You want to eliminate phosphogypsum waste
You aim for long-term sustainability and flexible ore sourcing
