In traditional phosphate fertilizer production, wet-process phosphoric acid is mainly used as an intermediate product in the manufacture of basic fertilizers such as ammonium phosphate and superphosphate, with a relatively independent process. However, with increasing environmental pressure and dwindling phosphate rock resources, a new industrial model is emerging—the deep integration of wet-process phosphoric acid with fertilizer production processes. This article analyzes how this trend is reshaping the fertilizer production landscape from three dimensions: technological path, economic benefits, and green transformation.
What is the Deep Integration of Wet-Process Phosphoric Acid with Fertilizer Production?
Wet-process phosphoric acid refers to phosphoric acid produced by decomposing phosphate rock with sulfuric acid, traditionally mainly used in the production of phosphate fertilizers. Deep integration refers to the systematic integration of the production, purification, and subsequent fertilizer manufacturing stages of wet-process phosphoric acid, forming a vertically integrated industrial chain of “phosphate rock → wet-process phosphoric acid → fertilizer/fine phosphate/new energy materials.”
Based on industry practice, deep integration includes at least three levels:
Process Coupling: Synergistic use of nitric acid phosphate fertilizer and wet-process phosphoric acid technology, primary decalcification to produce calcium ammonium nitrate, secondary decalcification to produce high-purity phosphate
By-product Resource Utilization: Recovery of fluorosilicic acid to produce anhydrous hydrogen fluoride, phosphogypsum to produce building materials or roadbed materials
Cascade Utilization: Refined phosphoric acid for new energy materials, crude acid for producing fertilizers specifically for acidic soils
Core Technology Path: From “Single Production” to “Combined Production”
2.1 Nitric Acid Phosphate Fertilizer and Wet-Process Phosphoric Acid Coupling Technology
This technology uses the cryogenic nitric acid phosphate fertilizer as the basic process, performing primary decalcification (80% decalcification rate) to obtain calcium nitrate tetrahydrate, which is then used to produce fully water-soluble calcium ammonium nitrate. Secondary decalcification uses sulfuric acid phosphate fertilizer technology (or wet-process phosphoric acid technology), adding sulfuric acid or ammonium sulfate, crystallizing, and filtering, achieving a decalcification rate of over 99%, yielding white dihydrate gypsum.
Key advantages: The filtrate after decalcification, after neutralization, concentration, and granulation, can produce 26-13 nitrate phosphate fertilizer; if nitrate phosphate fertilizer is not produced, the clarified filtrate can be concentrated, denitrified, cooled, crystallized, and dried to obtain industrial-grade monoammonium phosphate (MAP). This means that the same equipment can flexibly switch products according to market demand.
2.2 Hemihydrate-Dihydrate Wet Process Phosphoric Acid Technology The hemihydrate-dihydrate wet process phosphoric acid technology independently developed by China Wuhuan Engineering Co., Ltd. is a typical example of deep integration. Its core innovations include:
Calcium sulfate metastable hemihydrate crystallization control technology:By precisely controlling parameters such as reaction temperature, phosphorus pentoxide concentration, and reaction time, calcium sulfate precipitates in an ideal hemihydrate crystal form.
Hydrated crystal phase reconstruction and efficient dissolution and release of intercrystalline phosphorus:Overcoming the bottleneck of difficult release of intercrystalline phosphorus in traditional technologies, improving phosphorus utilization.
Sulfuric acid dispersion injection into hemihydrate slurry dual-circulation high-level flash evaporation technology:Ensuring uniform sulfuric acid reaction and rapid separation of water and heat generated during the reaction.
Hard data:Compared to traditional dihydrate plants, overall energy consumption is reduced by 52%, phosphorus recovery rate is increased to 98.5%, and the total phosphorus content of phosphogypsum is less than 0.5%. Currently, 12 production units of this technology have been built domestically and internationally, with a total capacity of 2.8 million tons/year.
2.3 Wet process phosphoric acid preparation of water-soluble ammonium polyphosphate
Water-soluble ammonium polyphosphate (APP) is a new type of fertilizer with advantages such as high nutrient content and good chelation performance with metal ions. Using wet-process phosphoric acid, urea, and ammonia as main raw materials, under optimized conditions—MAP slurry neutralization degree 0.8, MAP slurry:urea = 5:1, reaction time 4 hours, and reaction temperature 200℃—APP product with P₂O₅ content 55.19%, N content 17.07%, and average degree of polymerization 2.04 can be obtained.
Economic Benefits: Compared with using industrial monoammonium phosphate as raw material, this process can reduce costs by about 20%.
III. Empirical Evidence of Economic Benefits: Practical Data on Cost Reduction and Efficiency Improvement
3.1 Cost Advantage: Using the coupled technology of nitric acid phosphate fertilizer and wet-process phosphoric acid, the manufacturing cost of 26-13 nitric acid phosphate fertilizer is within 1550 yuan/ton (after deducting by-products), with a profit of about 800 yuan/ton. The cost of industrial monoammonium phosphate is 600-800 yuan/ton lower than that of the sulfuric acid process.
Environmental Benefits: Phosphogypsum Reduction and Resource Utilization
Phosphogypsum is a major byproduct of wet-process phosphoric acid production, generating approximately 5 tons of phosphogypsum for every ton of phosphoric acid produced. Deep integration technology addresses this issue from two directions: source reduction and end-use utilization.
Source Reduction: The hemihydrate-dihydrate technology controls the total phosphorus content of phosphogypsum below 0.5%, significantly improving quality and creating conditions for subsequent utilization.
End-Use Utilization: Phosphogypsum can be used to produce building materials and highway subgrade materials, or, after modification, can be safely stockpiled. Simultaneously, fluorosilicic acid generated during wet-process phosphoric acid production can be transformed from waste into high-value-added anhydrous hydrogen fluoride.
Industrial Chain Extension: From Fertilizers to New Energy Materials
Another direction of deep integration is the extension to new energy materials. Industrial phosphoric acid and industrial monoammonium phosphate produced using nitric acid wet-process phosphoric acid technology can serve as precursors for ferric phosphate.
Market Background: The demand for ferric phosphate was approximately 2 million tons in 2023 and is projected to reach 3-3.5 million tons by 2025. From a cost structure perspective, phosphorus source costs account for 53% of the production cost of iron phosphate. Chemical companies with access to phosphorus resources have a significant cost advantage.
Conclusion: The deep integration of wet-process phosphoric acid with fertilizer production processes is moving from a “concept” to “large-scale industrialization.” Its core value is reflected in three levels:
Economic level: Through co-production models and by-product resource utilization, it significantly reduces the cost of single products and enhances the company’s resilience.
Environmental level: It reduces phosphogypsum emissions, increases fluorine recovery rates, and achieves full utilization of phosphorus resources.
Strategic level: It extends the industrial chain to the field of new energy materials, opening up a second growth curve for traditional phosphate fertilizer companies.
For companies planning to build or upgrade phosphate fertilizer production lines, it is recommended to prioritize evaluating the applicability of nitrate phosphate fertilizer coupled with wet-process phosphoric acid technology or hemihydrate-dihydrate wet-process phosphoric acid technology. According to supporting solutions provided by equipment manufacturers such as Huaqiang Heavy Industry, the investment payback period for these two technology routes is typically 2-4 years, and they can meet increasingly stringent environmental regulations.
The deep integration of wet-process phosphoric acid with downstream fertilizer manufacturing represents a paradigm shift that extends far beyond phosphate chemistry alone. This vertically coupled model naturally synergizes with modern compound and organic fertilizer infrastructure, enabling producers to architect versatile production ecosystems. A fully integrated facility can simultaneously host an npk fertilizer line for high-analysis compound products, a bio organic fertilizer production line for sustainable soil amendments, and a roller press granulator production line for specialty slow-release formulations— all drawing purified phosphoric acid from a unified upstream wet-process unit.
Moreover, standardized auxiliary systems such as the fertilizer dryer machine, fertilizer cooler machine, and rotary drum screening machine can be shared across multiple product trains, maximizing capital efficiency and simplifying maintenance protocols. The final fertilizer packing machine stage ensures consistent bagging quality regardless of product type. By unifying phosphoric acid purification with flexible downstream granulation, drying, and packaging modules, enterprises gain the agility to pivot between commodity fertilizers, premium organics, and even new-energy precursors—transforming what was once a linear, resource-intensive process into a resilient, circular industrial platform.