fertilizer production line

Introduction

In modern organic fertilizer production, selecting the appropriate granulation technology is crucial. Different granulation processes have their own characteristics in terms of capacity, energy consumption, raw material adaptability, and product quality. Understanding these differences helps production enterprises make informed choices based on their own conditions and market demands. This article introduces three mainstream organic fertilizer granulation technologies to help readers find the most suitable production solution for their needs.

Overview of Three Mainstream Technologies

Currently, the organic fertilizer industry mainly uses three granulation processes: horizontal mixing and extrusion granulation, flat die extrusion granulation, and rotary drum granulation. Each technology has its unique working principle and applicable scenarios, and the selection requires consideration of factors such as raw material characteristics, product requirements, and investment budget.

Horizontal mixing and extrusion granulation technology uses the mechanical action of a spiral mixing shaft to shape materials, making it particularly suitable for organic raw materials with high moisture content. Flat die extrusion granulation uses the cooperation of a die and pressure rollers to extrude materials, requiring strict control over the moisture content of the raw materials. Rotary drum granulation uses the rotation of a drum to agglomerate materials, usually requiring a drying system.

Raw Material Adaptability Comparison

Raw material characteristics are the primary consideration when selecting granulation technology. Horizontal stirred extrusion granulation has the widest adaptability to raw materials, capable of directly processing organic materials with a moisture content of 25%-45%, including livestock and poultry manure, straw, mushroom residue, and various other organic wastes. This tolerance makes it an ideal choice for processing agricultural waste.

Flat die extrusion granulation requires the raw material moisture content to be controlled between 15%-25%, making it more suitable for pre-treated organic materials or some compound fertilizer production. Drum granulation has the strictest requirements for raw material moisture, typically needing to reduce the moisture content to 10%-20%, thus requiring a drying system, increasing energy consumption and equipment investment.

Capacity and Efficiency Analysis

From a capacity perspective, each of the three technologies has its advantages. A medium-sized horizontal stirred extrusion granulation production line has a capacity of 3-8 tons/hour, which can meet the needs of most organic fertilizer production enterprises. Flat die extrusion granulation has a relatively lower capacity, with a medium-sized line of 0.4-2.5 tons/hour, suitable for small-scale or specialty fertilizer production. Rotary drum granulation boasts the highest production capacity, with medium-sized lines reaching 5-12 tons/hour, but its energy consumption is also the highest.

In terms of energy efficiency, horizontal mixing extrusion granulation excels. Since it eliminates the need for drying, its energy consumption per ton of fertilizer is only 20-30 kWh, far lower than the drying required by rotary drum granulation. This energy efficiency advantage is particularly important given the rising energy costs.

Product Quality Characteristics: Products produced by different granulation technologies differ in appearance and properties. Horizontal mixing extrusion granulation produces irregular spherical or cylindrical particles with high strength, easily disintegrating upon contact with water, making it ideal for field application of organic fertilizers. Flat die extrusion granulation produces regular cylindrical particles with a neat appearance. Rotary drum granulation produces standard spherical particles with the best commercial appearance.

For bio-organic fertilizers, the low-temperature characteristics of horizontal mixing extrusion granulation offer a unique advantage. It ensures a survival rate of over 95% for the biological agents in the product, while the high-temperature process in rotary drum granulation leads to the inactivation of most microorganisms.

Investment and Operating Costs

In terms of initial investment, flat die extrusion granulation lines have the lowest cost, with medium-sized lines costing approximately 500,000-800,000 RMB; horizontal stirred extrusion granulation lines are in the middle, costing approximately 800,000-1,200,000 RMB; and rotary drum granulation lines are the most expensive, reaching 1,500,000-2,000,000 RMB. This difference mainly stems from variations in equipment complexity and supporting systems.

Operating costs include energy consumption, maintenance, and labor costs. Horizontal stirred extrusion granulation has the greatest long-term operating cost advantage due to its low energy consumption and simple maintenance. While rotary drum granulation offers high capacity, its high energy consumption and maintenance costs may offset its capacity advantage.

Selection Guidelines

When choosing a granulation technology, the following factors should be considered:

If the main processing involves organic waste with high moisture content, and low energy consumption and bioactivity protection are prioritized, horizontal stirred extrusion granulation is the best choice.

If the raw materials are pretreated, moisture content is well controlled, and the production scale is relatively small, flat die extrusion granulation may be more suitable.

If the highest capacity and best product appearance are desired, and higher energy costs are acceptable, rotary drum granulation is worth considering.

For most organic fertilizer producers, especially those using agricultural waste as raw materials and focusing on the bioactivity of their products, horizontal mixing and extrusion granulation offers the best cost-effectiveness. It not only suits the actual conditions of organic fertilizer production in China but also aligns with the global trend towards sustainable agriculture.

Future Outlook

With continuous technological advancements, these granulation processes are converging and developing. The addition of intelligent control systems makes operation more precise, the use of new materials extends equipment lifespan, and process optimization improves product quality. In particular, horizontal mixing and extrusion granulation technology is continuously innovating, maintaining its original advantages while gradually improving product appearance and expanding its application range.

Regardless of the technology chosen, successful production relies on meticulous management of raw materials, a deep understanding of the process, and strict quality control. With the increasing global emphasis on organic agriculture and sustainable production, choosing the right granulation technology will become one of the key factors for the success of organic fertilizer companies.

Strategic Choice for Sustainable Production

In conclusion, selecting the optimal granulation technology is a strategic decision that balances raw material properties, production goals, and economic viability for any organic fertilizer manufacturing operation. Horizontal stirred extrusion, flat die, and drum granulation each serve distinct niches within the industry.

The choice of fertilizer granulation technology is just one part of a complete organic fertilizer production line. It begins with efficient organic fertilizer fermentation, supported by robust fermentation composting turning technology using equipment like a chain compost turning machine or large wheel compost turning machine. The granulation stage—whether using a new type organic fertilizer granulator, a flat die pelleting machine, or traditional drum granulation—shapes the final product. For a bio organic fertilizer production line, preserving microbial viability during granulation becomes the paramount technical consideration.

Ultimately, a successful operation integrates the right preprocessing, fermentation, and granulation technologies to produce high-quality, market-ready organic fertilizers efficiently and sustainably.

Microbial fertilizers, also known as microbial fertilizers, are a type of fertilizer made with specific live beneficial microorganisms as the core functional component, combined with organic matter, carriers, or small amounts of nutrients. They themselves do not contain macro- or micronutrients; their core function is to improve the soil’s micro-ecological environment, activate soil nutrients, and stimulate crop growth through the life activities of microorganisms. When used in conjunction with chemical fertilizers and organic fertilizers, they achieve multiple effects of “promoting growth, resisting disease, and improving quality,” making them a key fertilizer category for developing green agriculture.

Core Mechanism of Action

The efficacy of microbial fertilizers depends entirely on the metabolic activities of beneficial microorganisms, primarily through the following four pathways:

Activating Soil Nutrients and Enhancing Fertilizer Utilization

The soil contains a large amount of “fixed” nutrients that are difficult for crops to directly absorb (such as insoluble phosphorus, potassium, and organic nitrogen). Beneficial microorganisms can secrete organic acids and enzymes to decompose and convert these nutrients into soluble nutrients.

Phosphate-solubilizing bacteria: Secrete organic acids to dissolve calcium phosphate, iron phosphate, etc., in the soil, releasing available phosphorus.

Potassium-solubilizing bacteria: Decompose minerals such as feldspar and mica, releasing potassium ions.

Nitrogen-fixing bacteria: Convert atmospheric nitrogen into ammoniacal nitrogen for crop absorption (e.g., nitrogen fixation through symbiotic relationships between rhizobia and legumes).

Producing growth-promoting substances to stimulate crop growth: Beneficial microorganisms secrete plant growth regulators during metabolism, including auxins, cytokinins, and gibberellins, promoting root development, accelerating stem and leaf growth, and enhancing the crop’s ability to absorb water and nutrients.

Suppressing soil-borne diseases and mitigating continuous cropping obstacles: Beneficial microorganisms can seize living space around crop roots through “occupancy effects” and “antagonistic effects,” inhibiting the reproduction of pathogens; simultaneously, they secrete antibacterial substances (such as antibiotics and chitinase) to directly kill or inhibit soil-borne disease pathogens (such as wilt and root rot pathogens), thereby mitigating the accumulation of soil diseases caused by continuous cropping.

Improving Soil Structure and Optimizing the Micro-ecological Environment

Microbial metabolites (such as polysaccharides and humic acids) promote soil aggregate formation, improve soil aeration and water and fertilizer retention capacity; simultaneously, the proliferation of beneficial microorganisms regulates the balance of the soil microbial community, reduces the number of harmful microorganisms, and improves soil health.

Main Product Types and Applicable Scenarios

Based on the types and functions of the microorganisms they contain, microbial fertilizers can be divided into 5 categories, specifically tailored to the needs of different crops and soils:

Rhizobium Agents

Core Strain: Rhizobium (e.g., soybean rhizobium, peanut rhizobium).

Functional Characteristics: Forms root nodules in symbiosis with the roots of leguminous crops (soybeans, peanuts, peas, etc.), fixing atmospheric nitrogen and meeting 30%-80% of the crop’s nitrogen requirements, significantly reducing nitrogen fertilizer application.

Applicable Scenarios: Seed coating or base fertilizer for leguminous crops. Note the specificity of the strain and crop (e.g., soybean rhizobium cannot be used for peanuts).

Nitrogen-Fixing Bacterial Agents

Core strains: Free-living nitrogen-fixing bacteria and symbiotic nitrogen-fixing bacteria (e.g., *Azotobacter chrysophagus*).

Functional characteristics: Do not require symbiosis with crops; can independently fix nitrogen in the soil while secreting auxins to promote crop growth.

Applicable scenarios: Base fertilizer or top dressing for non-leguminous crops such as wheat, corn, and vegetables; suitable for improving nitrogen supply in poor soils.

Phosphorus- and potassium-solubilizing Bacterial Agents

Core strains: Phosphorus-solubilizing bacteria (e.g., *Bacillus megaterium*) and potassium-solubilizing bacteria (e.g., *Bacillus mucilaginosus*).

Functional characteristics: Decomposes fixed phosphorus and potassium elements in the soil, improving the utilization rate of phosphorus and potassium fertilizers and reducing fertilizer loss.

Applicable scenarios: Base fertilizer for field crops, fruit trees, and vegetables; especially suitable for plots with “soil compaction and nutrient fixation” caused by long-term application of chemical fertilizers.

Compound Microbial Agents

Core strains: A compound of multiple beneficial bacteria, including nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, potassium-solubilizing bacteria, and disease-resistant bacteria.

Features: Combines multiple functions of “nutrient activation + growth promotion + disease resistance,” with a wide range of applications and more comprehensive effects.

Applicable Scenarios: Base fertilizer and top dressing for various crops, and soil improvement in areas with continuous cropping obstacles.

Bio-organic Fertilizer

Core Components: Beneficial microorganisms + well-rotted organic fertilizer (carrier).

Features: Combines the advantages of organic fertilizer (“soil improvement, providing organic matter”) and microbial fertilizer (“nutrient activation, disease resistance, and growth promotion”), providing a gentle and long-lasting fertilizer effect.

Applicable Scenarios: Base fertilizer for facility agriculture, fruit trees, and vegetables; an excellent alternative to traditional chemical fertilizers.

III. Core Advantages

Improved fertilizer utilization rate and reduced fertilizer usage

When used in conjunction with microbial fertilizers, it can increase fertilizer utilization rate by 10%-30%, reducing soil pollution and nutrient loss caused by excessive fertilizer application.

Relieves Continuous Crop Obstacles and Improves Soil Health

For greenhouse vegetables, fruit trees, and other fields with long-term continuous cropping, it effectively inhibits soil-borne diseases, restores the soil micro-ecology, and solves the problem of “repeated cropping leading to reduced yields.”

Green and Environmentally Friendly, Enhancing Agricultural Product Quality

Microbial fertilizers are non-toxic and harmless, leaving no residue in crops. After application, they can improve the taste, sweetness, and safety of agricultural products, meeting the production needs of green and organic foods.

Complementary and Synergistic with Other Fertilizers

Used in conjunction with chemical fertilizers, it can prevent “root burn”; used in conjunction with organic fertilizers, it can accelerate the decomposition of organic fertilizers and enhance their effectiveness.

Precautions for Use

Maintaining microbial activity is key.

Store in a cool, dry, and well-ventilated place, avoiding direct sunlight (ultraviolet rays will kill beneficial bacteria) and high temperature and humidity environments.

Avoid mixing with fungicides, insecticides, and other pesticides. If necessary, allow an interval of 7-10 days.

Prepare and use immediately whenever possible; diluted microbial fertilizer solutions should not be stored for extended periods.

Strictly follow application methods: Seed dressing and root dipping are more effective than broadcasting, allowing microorganisms to be closer to the crop roots. When used as a base fertilizer, it must be thoroughly mixed with the soil to avoid concentrated application that could lead to excessively high local microbial concentrations.

Properly combine with other fertilizers; do not replace chemical fertilizers: Microbial fertilizers cannot replace chemical and organic fertilizers. They must be applied in combination with chemical and organic fertilizers according to the crop’s needs to meet its nutrient requirements throughout its entire growth cycle.

Pay attention to soil compatibility: The activity of beneficial microorganisms is greatly affected by soil pH, temperature, and humidity. They thrive in soils with a pH of 6.0-7.5. Excessively dry or waterlogged soils will inhibit microbial activity.

Conclusion: Integrating Microbial Solutions into Modern Fertilizer Systems

In summary, microbial fertilizers represent a fundamental shift toward biological soil management, enhancing nutrient cycling, soil health, and crop resilience. Their success hinges on maintaining microbial viability and integrating them effectively with conventional nutrient sources.

For manufacturers, microbial inoculants can be incorporated into a complete bio organic fertilizer production line. This begins with producing a high-quality organic base via windrow composting machine technology. The resulting compost can then serve as a carrier for beneficial microbes. For producing compound fertilizers, an npk fertilizer production line using an npk blending machine and granulation equipment like a disc granulator (part of a disc granulation production line), a double roller press granulator, or a roller press granulator production line can be used to create blended or coated products that combine chemical nutrients with microbial agents, following a precise npk fertilizer production process.

Ultimately, the future of sustainable agriculture lies in synergizing biological inputs with precision mineral nutrition, creating fertilizer systems that are both productive and regenerative.

Flat die pelleting production lines play a vital role in modern industrial production, improving the efficiency of material storage, transportation, and utilization by processing powdered materials into uniform granules. This article introduces the production line’s capacity characteristics, applicable materials, working principle, and selection recommendations to help global readers gain a comprehensive understanding of this technology.

Production Capacity Overview

The hourly output of flat die pelleting production lines varies significantly depending on the model, configuration, and material characteristics. Common small production lines (such as those used in laboratories or small-batch production scenarios) typically have an hourly output between 0.08 and 0.3 tons, with a power configuration of approximately 5.5 to 11 kW. Medium-sized production lines are suitable for small to medium-sized farms or fertilizer plants, with an hourly output of 0.4 to 2.5 tons and a power configuration of 15 to 55 kW. Large production lines are used for large-scale production, with an hourly output of 2.5 to 5 tons and a power configuration of 55 to 75 kW. For extra-large customized production lines, the hourly output can even reach 8 to 20 tons, with power requirements exceeding 90 kW.

Key factors affecting production capacity include material moisture content, particle size, viscosity, hardness, as well as die orifice diameter and roller pressure. Generally, the material moisture content should be controlled between 15% and 25%, the particle size is preferably less than 2 mm, and the die orifice diameter commonly ranges from 3 to 30 mm. Proper control of these parameters helps improve pelleting yield and production efficiency.

Main Application Areas: Flat die pelleting technology is widely used in multiple industries. In the fertilizer industry, it is suitable for the production of organic fertilizers, bio-organic fertilizers, and compound fertilizers. Raw materials include livestock and poultry manure, straw, and humic acid, with a pelleting yield typically exceeding 95%, high particle strength, and low secondary pulverization rate. In the feed industry, this technology is used to produce livestock, poultry, and aquatic pellet feed, retaining nutrients while maintaining a temperature rise below 30 degrees Celsius during processing. In the biomass energy sector, flat die pelleting can compress raw materials such as sawdust and straw into high-density fuel pellets, facilitating storage and combustion. Furthermore, this technology is also suitable for the chemical and mining industries, such as the pelleting of activated carbon, catalyst carriers, and mineral powders, especially suitable for low-viscosity and heat-sensitive materials. Working Principle and Structural Features: The flat die granulator works by using a motor-driven reducer to rotate the flat die. Under centrifugal force, the pressure rollers adhere to the die, forcing the material into the die holes and extruding it into cylindrical granules. Finally, a scraper cuts the granules into uniform lengths. The entire process is carried out at low temperatures (typically below 30 degrees Celsius), making it suitable for processing heat-sensitive materials.

The core components of the production line include pretreatment equipment (such as crushers and mixers), the main unit (including the flat die, pressure rollers, and scraper), and post-processing equipment (such as coolers and screening machines). The flat die is typically made of alloy steel or carburized steel, offering high wear resistance. Particle diameter can be adjusted between 3 and 50 mm, with a granulation rate generally exceeding 95%. Compared to drying granulation technology, flat die pelleting can reduce energy consumption by approximately 40%.

Technical Advantages and Applicable Scenarios

The advantages of flat die pelleting technology include low-temperature processing, which helps retain the bioactivity and nutrients of the material; lower moisture requirements, reducing drying energy consumption; simple equipment structure, low maintenance costs, and convenient die replacement, adaptable to various pellet sizes.

This technology is particularly suitable for the large-scale production of organic and bio-fertilizers, especially composted materials and low-viscosity materials. It provides a low-cost pelleting solution in biomass fuel and feed production. For heat-sensitive or low-viscosity powders in the chemical and mining industries, flat die pelleting is also an efficient pelleting method.

Selection and Operation Recommendations

When selecting a flat die pelleting production line, capacity requirements, material characteristics, and target pellet sizes must be considered. It is recommended to calculate the hourly output based on daily production requirements and reserve 10% to 20% redundancy. For materials with a moisture content exceeding 25%, drying equipment may be required; coarse fibrous materials are suitable for large-roller mills. Common pellet sizes include 3 to 8 mm (for fertilizers) and 6 to 12 mm (for biomass fuels).

During operation, it is recommended to control the raw material particle size to below 2 mm and maintain the moisture content between 18% and 22%. Regularly check the wear of the flat die and pressure rollers, and replace them promptly to maintain a high pelletizing rate. Matching cooling and screening equipment can ensure pellet uniformity and storage stability.

A Brief Comparison with Ring die pelleting

Compared to ring die pelleting, flat die pelleting is more suitable for low to medium production capacity (typically not exceeding 5 tons/hour) and low-viscosity, heat-sensitive, or coarse-fiber materials. Die replacement is simpler, and maintenance costs are lower. Ring die pelleting is suitable for high-volume demands and high-viscosity materials, with a capacity of over 10 tons/hour, but die replacement is more complex. In terms of pellet shape, flat die pelleting primarily produces cylindrical pellets, while ring die pelleting can produce cylindrical or near-spherical pellets.

In summary, flat die pelleting production lines are a flexible, efficient, and energy-saving pellet manufacturing solution suitable for multiple fields such as fertilizers, feed, biomass energy, and chemical and mineral products. By making appropriate selections and operating in a standardized manner, users can achieve their production goals of high quality and low cost.

Conclusion: Integrating Granulation Technologies for Optimal Production

In summary, Flat die pelleting production lines offer a versatile, low-energy granulation solution ideal for small to medium-scale operations, particularly in the organic fertilizer manufacturing process. Their strength lies in processing heat-sensitive and low-viscosity materials at low temperatures, preserving vital nutrients and bioactivity.

For producers aiming for a diversified product portfolio, integrating a flat die line with other advanced fertilizer processing machine technologies creates a robust system. For instance, while a flat die line is excellent for organic granules, a disc granulation production line or roller press granulator production line might be better suited for high-volume npk manufacturing process requirements. Together with equipment like a rotary drum granulator or a drum granulator in a complete npk production line, manufacturers can leverage the full spectrum of npk fertilizer production technology to meet diverse market demands efficiently.

Ultimately, the strategic choice of granulation technology—whether flat die, disc, or roller press—should be driven by material properties, desired capacity, and final product specifications. By selecting the right system, producers can achieve high-quality granule production with optimal cost-efficiency and flexibility.

Introduction: A Model of Cross-Disciplinary Innovation in the Circular Economy

Amid the global wave of energy transition, the popularity of electric vehicles has brought about an increasingly severe challenge—the fate of a large number of retired lithium iron phosphate (LFP) power batteries. Traditional hydrometallurgical recycling primarily focuses on extracting lithium, which is economically suboptimal and fails to fully utilize the phosphorus resource that constitutes nearly 40% of the battery’s mass. Simultaneously, modern agriculture faces the dual challenges of acidic soil remediation and low phosphorus fertilizer efficiency. A groundbreaking technology ingeniously connects these two seemingly unrelated problems. Through innovative chemical processes, it directly converts retired LFP batteries into a slow-release phosphorus fertilizer that performs exceptionally well in acidic soils. This is not only a major innovation in the field of resource recovery but also opens a new path for nutrient supply in green agriculture, serving as a vivid practice of the circular economy concept at the intersection of new energy and agriculture.

I. Core Technology: A Four-Step Transformation from Battery to Fertilizer

This technology follows a clear, efficient, and environmentally friendly process route, divided into four key steps that achieve the precise conversion from waste electrode materials to functional fertilizer.

Step 1: Mild and Efficient Electrode Delamination

The process begins with separating the battery cathode active material from the aluminum foil current collector. Unlike traditional strong acid stripping or high-temperature incineration, this technology employs a mild chemical stripping solution assisted by ultrasonic treatment. The cavitation effect generated by ultrasound efficiently breaks the adhesion of the binder (e.g., PVDF) while avoiding harsh reactions that could damage the crystal structure of the active material. This step yields uniform, high-purity lithium iron phosphate (LiFePO₄) black powder, laying the foundation for subsequent selective extraction.

Step 2: Selective Lithium Extraction and Retention of Phosphorus-Iron Solid Phase

This is the key to the economic viability of the entire process. Using mild oxidants such as sodium persulfate (Na₂S₂O₈) under specific conditions, lithium ions (Li⁺) in LiFePO₄ are selectively oxidized and leached into the solution, while iron (Fe) and phosphorus (P) elements are retained in the solid phase as insoluble iron phosphate (FePO₄). This method achieves efficient, high-purity lithium recovery (which can be subsequently converted into lithium carbonate products) while ensuring that phosphorus and iron resources are not lost. This precise separation creates the conditions for the targeted utilization of phosphorus.

Step 3: Efficient Phosphorus Release and Resource Conversion

The solid phase after delithiation is mainly FePO₄, from which phosphorus needs to be released and converted into a plant-available form. Through reaction with reagents such as sodium sulfide (Na₂S), phosphorus is efficiently transferred into an aqueous solution in the form of specific ions (e.g., dihydrogen phosphate, H₂PO₄⁻). The phosphorus recovery rate in this step is extremely high, exceeding 99.5% under laboratory conditions, ensuring maximum resource utilization. It is worth noting that the by-products of this reaction (e.g., iron sulfide) also have potential value as photocatalytic materials, further embodying the zero-waste concept of “utilizing everything to the fullest.”

Step 4: Synthesis of Acid-Resistant Slow-Release Phosphorus Fertilizer

This is the functional core of the technology. The obtained phosphorus-containing solution (containing precisely controlled molar ratios of hydrogen phosphate, HPO₄²⁻, and dihydrogen phosphate, H₂PO₄⁻) is used as a functional monomer and mixed with raw materials such as acrylic acid and urea. In the presence of an initiator and under nitrogen protection, free radical polymerization is carried out at 50-80°C. The key to this reaction is that phosphate ions act as cross-linking agents and stabilizers, forming a dense hydrogen bond network with the carboxyl groups on the polyacrylic acid chains and creating an interpenetrating structure with urea, ultimately building a stable three-dimensional polymer hydrogel network. The fertilizer nutrient (phosphorus) is chemically bonded or physically encapsulated within this network.

II. Core Advantages: Triple Breakthroughs in Economics, Performance, and Environmental Protection

The disruptive potential of this technology stems from its significant advantages across multiple dimensions.

• Disruptive Economic Model:Traditional LFP battery recycling suffers from poor economics due to the lack of high-value cobalt and nickel. This technology adopts a “lithium + phosphorus” dual-recovery model, converting the phosphorus that constitutes the bulk of the battery mass into high-value-added agricultural products. Calculations estimate that introducing this technology can yield a net profit of approximately $2,035 per ton of retired batteries processed, completely reversing the “unprofitable” situation of LFP recycling and providing strong commercial drivers for the recycling industry.
• Outstanding Acid-Resistant Slow-Release Performance:Traditional polymer slow-release fertilizers tend to have their network structure collapse due to protonation in acidic soils, leading to nutrient “burst release” or failure. In the fertilizer synthesized by this technology, phosphate groups play a dual role: first, as strong hydrophilic groups and cross-linking points, they enhance the stability and water retention of the network in acidic environments; second, they possess pH buffering capacity, partially neutralizing soil acidity and providing an ideal microenvironment for steady, long-lasting nutrient release. This makes it particularly suitable for the vast areas of acidic red and yellow soils in southern China.
• Green and Environmentally Friendly Throughout the Process:The entire process avoids the use of strong acids, strong alkalis, or high-temperature calcination. The reagents are mild, and by-products can be resource-utilized, basically generating no difficult-to-treat secondary pollution. The transformation from electronic waste to an environmentally friendly fertilizer achieves true clean production and a closed resource loop.

III. Application Prospects and Future Directions

The successful development of this technology holds broad application value and profound social significance.

In Agriculture: It provides an innovative product to address the worldwide challenges of severe phosphorus fixation in acidic soils and low fertilizer efficiency. Preliminary experiments indicate that this fertilizer can effectively promote the growth of crops like corn. It can achieve the same or even higher yields while reducing phosphorus fertilizer application by 30%-50%, significantly lowering the risk of phosphorus loss through runoff. This has a positive effect on protecting water bodies and preventing eutrophication.

In Resource Circulation: It points the way for the high-value, resource-based utilization of millions of tons of retired LFP batteries annually. It is a key technological node in constructing the grand cycle of “battery production – use – recycling – material regeneration – agricultural feedback,” strongly supporting the sustainable development of the new energy vehicle industry.

Future Development Focus: Current research is primarily at the laboratory stage. Future work will focus on: 1) Process Engineering Scale-up: Optimizing continuous production processes, reducing equipment and operational costs, and promoting the industrialization of the technology; 2) Systematic Agricultural Validation: Conducting large-scale, long-term field trials on various types of acidic soils and multiple crops to comprehensively evaluate its agronomic effects and environmental benefits; 3) Product Series Development: Building on the existing phosphorus fertilizer, introducing potassium, calcium, magnesium, and trace elements to develop specialized compound slow-release fertilizers for different scenarios such as dryland farming, protected horticulture, and economic forests; 4) Technology Extension Applications: Exploring the application of this technological concept to the resource treatment of other phosphorus-containing wastes (e.g., phosphorus-rich sludge, phosphogypsum), expanding its application boundaries.

Converting discarded lithium iron phosphate batteries into acid-resistant, slow-release phosphorus fertilizer is a cutting-edge technology that integrates materials science, environmental engineering, and agronomy. It cleverly solves the dual challenges of “difficult disposal of waste batteries” and “difficult fertilization of acidic soils,” achieving a transformative “waste-to-resource” solution. This technology not only demonstrates the immense potential of interdisciplinary resource recycling but also provides a highly promising technological blueprint for the green transformation of global agriculture and the closed-loop development of the new energy industry. As the technology matures and is widely adopted, we have reason to believe that these batteries, which once powered electric vehicles and traveled thousands of miles, will continue to nourish the earth in another form after their retirement, sustaining life for generations to come.

A Circular Blueprint: From Batteries to Farmland

The conversion of spent lithium iron phosphate batteries into acid-resistant, slow-release phosphorus fertilizer represents a paradigm shift in resource recovery. This interdisciplinary innovation addresses both critical waste management and sustainable agriculture challenges, creating a truly circular “waste-to-resource” pathway with significant environmental and economic potential.

To scale this transformative process, the recovered nutrient materials can be integrated into conventional fertilizer granulation processes. The phosphorus-rich compound can be blended into formulations using an npk blending machine and then shaped into uniform granules via advanced granulation technology. Depending on the desired product characteristics, a disc granulator (as part of a disc granulation production line) or a double roller press granulator can be employed within a complete npk fertilizer production line. This integration with professional fertilizer manufacturing equipment ensures the final product meets agronomic standards for efficient, controlled-release application.

Ultimately, this technology exemplifies a powerful synergy between the new energy and agriculture sectors. It promises a future where batteries, after powering our vehicles, can be reborn as vital nutrients that nourish crops and regenerate soils, closing the loop in a truly sustainable economy.