Introduction
Natural graphite has become the mainstream choice for lithium-ion battery anode materials due to its excellent electrical conductivity, high crystallinity, and favorable layered structure. However, raw natural graphite exhibits a flaky structure with high anisotropy. During electrode coating, this leads to random orientation, resulting in non-uniform packing density and poor electrolyte wettability. Additionally, the sharp edges of flaky particles can easily puncture separators and cause localized stress concentration during lithium-ion intercalation.
The spheroidization process transforms irregular graphite flakes into near-spherical particles (typical particle size D50: 10-25μm) through precisely controlled mechanical impact forces, significantly improving the material’s physical and electrochemical properties. According to MDPI 2023 research, spheroidization treatment can increase graphite surface area by 1.8 times and optimize pore network structure, thereby enhancing volumetric energy density, improving cycle life, and enhancing fast-charging capabilities.
With the rapid growth of the electric vehicle market, global demand for spherical graphite continues to rise. However, traditional spheroidization processes typically achieve yields below 50%, meaning more than half of the raw material is converted into fine powder waste (particle size <10μm), severely constraining the industry’s sustainable development. Therefore, deeply understanding the technical principles of different spheroidization equipment and optimizing process routes to improve yield has become a core competitiveness for anode material producers.
Featured Snippet
Spheroidization is a critical process in natural graphite anode material production, directly impacting the energy density and cycle performance of lithium-ion batteries. This article systematically compares two major technical approaches—airflow impact and mechanical impact—with particular focus on analyzing three equipment types within mechanical impact: rotor impact, classifier mill, and continuous cascade systems. The analysis covers technical principles, performance parameters, and application scenarios. Research indicates that rotor impact equipment (such as Alpine APR, NETZSCH GyRho) achieves yields of 55-80%, classifier mill equipment in single-machine mode achieves yields of 50-70%, while traditional continuous cascade systems achieve only 30-50%. By adopting a two-stage separation process (grinding + shaping), the comprehensive yield of classifier mill equipment can be increased to 60-75%, saving 40-60% of raw materials compared to traditional solutions. Incorporating the latest international research findings, this article provides scientific equipment selection guidance for anode material producers.
Technical Classification of Spheroidization Equipment
Classification by Technical Principle
Airflow Impact Type
Airflow impact equipment utilizes high-velocity gas streams to drive particle-to-particle collisions and grinding, primarily applied in spheroidization of high-hardness materials like diamond and silicon carbide. According to MDPI 2023 research, while this equipment offers advantages of narrow particle size distribution and low contamination, it suffers from high energy consumption and low throughput, and is unsuitable for tough graphite materials. Its application in graphite anode materials is limited.
Mechanical Impact Type
Mechanical impact equipment represents the mainstream technical approach for graphite spheroidization, applying impact, friction, and shearing forces to graphite particles through high-speed rotating rotors or grinding discs. According to the description in Chinese Patent CN102951633A, the shaping principle of this equipment includes two mechanisms: impact shaping and friction shaping, with shaping intensity precisely controlled through speed adjustment and circulation channels. Due to its lower cost and particular suitability for graphite’s toughness characteristics, mechanical impact equipment has become the preferred solution for anode material companies worldwide.
Subcategories of Mechanical Impact Type
Based on differences in mechanical structure and operating modes, mechanical impact spheroidization equipment can be further subdivided into three categories:
- Rotor Impact: Employs high-speed rotors with hammers or blades, achieving spheroidization through pure impact and shearing action. Representative equipment includes Alpine APR and NETZSCH GyRho.
- Classifier Mill: Utilizes grinding disc and ring gear structures with integrated classifier wheel systems, completing shaping through combined grinding, impact, and friction. Representative equipment includes Hosokawa ZPS and domestic ZD-ZXJ series.
- Continuous Cascade: Links 20-30 mechanical mills in series, with particles continuously passing through multiple impacts to complete spheroidization, suitable for ultra-large-scale production.
Rotor Impact Batch Shaping Machines
Technical Principles and Equipment Characteristics
Rotor impact equipment represents a significant breakthrough in spheroidization technology in recent years. According to ScienceDirect 2022 research, this equipment employs a closed chamber structure where graphite particles accelerate under the drive of a high-speed rotating rotor. Through overlapping impact forces between particles and rotor hammers, plus friction or shearing forces between particles and chamber walls, flaky graphite gradually curls into spheres. The entire process operates in batch mode, with single batch processing times as short as 3-15 minutes.
Compared to traditional cascade systems, the most significant advantage of rotor impact equipment lies in its integrated dynamic classification system. The classifier wheel precisely controls the cut size through speed adjustment, with qualified products separated promptly and collected via cyclone separators, while substandard particles continue circulating in the chamber for further shaping until reaching target size. This real-time online classification mechanism effectively reduces fines generated from excessive grinding and is the key technology for yield improvement.
Mainstream Equipment Performance Comparison
Alpine APR Series
The Alpine APR (Particle Rounder) was specifically developed by Hosokawa Alpine for natural graphite spheroidization. According to Hosokawa official materials, APR employs a completely innovative process that can complete batch shaping in just 3 minutes, achieving yields of 55-75%, with process optimization potentially reaching 80%, while flexibly adjusting product particle size to the D50: 10-25μm range. Compared to traditional cascade systems, APR reduces energy consumption by approximately 50%, with significantly lower footprint and maintenance costs.
NETZSCH GyRho System
NETZSCH developed the GyRho rounding unit optimized for batch spheroidization. According to MDPI 2023 research, the GyRho system achieves 55% yield within 15 minutes of processing time, with extended processing potentially increasing yield to 70%. The system produces spherical graphite with a tap density of 963 g/L (0.963 g/cm³), particle size D50 of 16.8μm, and narrow, uniform particle size distribution, particularly suitable for high-end applications with strict battery performance requirements.
Hosokawa Faculty Series
Hosokawa’s Faculty series also employs batch shaping processes. According to ALPA 2023 technical review, this series controls combined effects of high-velocity airflow impact, hammer collisions, friction, and shearing to increase tap density from initial 0.5 g/cm³ to 1.0 g/cm³, achieving 100% density improvement while maintaining 55-75% yield within reasonable processing times.
Technical Advantages Summary
Core advantages of rotor impact equipment include:
- High Yield: Through precise control of impact intensity and real-time classification, yields reach 55-80%, significantly higher than traditional cascade systems’ 30-50%.
- Short Cycle: Single batch processing time of 3-15 minutes dramatically improves production efficiency.
- Low Energy Consumption: Approximately 50% energy reduction compared to traditional solutions.
- Flexibility: Can flexibly adapt to different particle size requirements through speed and processing time adjustments.
Classifier Mill Batch Shaping Machines
Technical Principles and Structural Characteristics
Classifier mill equipment employs a grinding disc and ring gear combination structure, applying grinding and impact forces to graphite particles through high-speed disc rotation while integrating a classifier wheel system for online classification. According to MDPI 2023 equipment improvement research, the working principle of this equipment relies primarily on rotor impact and shearing action on particles to achieve surface modification, representing the mainstream method for graphite spheroidization.
The typical process flow for classifier mill equipment is: uniform feeding → grinding shaping → classification screening → finished product collection → fines collection. Within the grinding chamber, qualified products are screened through the classifier wheel and discharged via the outlet pipe, while substandard products automatically return to the grinding chamber for continued processing until reaching target particle size. This intelligent circulation finishing mechanism ensures product quality stability.
International Mainstream Equipment
Hosokawa ZPS Classifier Mill
Hosokawa’s ZPS (Zirkoplex) classifier mill is widely used globally. According to Hosokawa official materials, while ZPS can also be used for graphite rounding, it requires more energy and space compared to the APR system. This equipment performs excellently in artificial graphite processing because artificial graphite is already relatively spherical after grinding, requiring lower shaping energy, but has limited processing yield for natural graphite.
Technical Features of Domestic ZD-ZXJ Series
The domestic ZD-ZXJ series classifier shaping machine, while inheriting classifier mill technical principles, has been optimized for Chinese market demands with the following key technical features:
Integrated Structural Design
Adopts integrated structure with upper ultra-fine classifier and lower ultra-fine pulverizer, integrating primary separation function within the main unit, reducing equipment quantity and footprint.
Intelligent Circulation Finishing System
Substandard products automatically return to the crushing chamber for continued grinding until qualified, enabling in-process quality control and reducing manual intervention.
Dual Drive System
Crushing disc and classifier wheel employ independent drive systems with separately adjustable speeds, adapting to different raw material characteristics and product specification requirements.
Two-Stage Process Compatibility
Can switch to gentle shaping mode, coordinating with pre-grinding equipment to form a two-stage separation process, reducing fines generation.
Performance Parameters and Application Range
In single-machine mode, classifier mill equipment typically achieves yields of 50-70% for natural graphite, falling between rotor impact (55-80%) and continuous cascade (30-50%). Its main advantages include:
- System Simplicity: Integrated design reduces equipment quantity and footprint.
- Quality Stability: Intelligent circulation mechanism ensures batch-to-batch consistency.
- Strong Adaptability: Dual system independent drive adapts to various raw materials and specifications.
- Cost-Effectiveness: Particularly suitable for medium-sized enterprises prioritizing initial investment and operating costs.
Continuous Cascade Systems
Technical Principles
Continuous cascade systems represent the traditional process for graphite spheroidization, linking 20-30 vortex mills or air jet mills in series, with graphite particles continuously passing through multiple units, gradually forming spheres after 8-12 shaping cycles. According to ALPA 2021 process review, the single-pass spheroidization rate of this traditional process is typically below 40%, requiring multiple cycles to achieve target morphology.
Performance Characteristics and Limitations
The main performance parameters of continuous cascade systems are as follows:
- Yield: According to ScienceDirect 2022 research, traditional spheroidization processes typically achieve yields around 50%, with most enterprises’ actual production yields in the 30-50% range, meaning at least half the raw material is converted to fine powder waste.
- Energy Consumption: Operating 20-30 units in series results in extremely high energy consumption.
- Footprint: Large number of units requires substantial floor space.
- Maintenance: Maintenance costs and complexity significantly increase with multiple units.
Additionally, according to Springer 2025 carbon footprint research, spheroidization accounts for approximately 20% of total carbon emissions (9.6 kg CO₂/kg) in Chinese coated spherical graphite production, with the high energy consumption of traditional cascade systems being a major source of carbon emissions.
Despite these limitations, continuous cascade systems remain suitable for ultra-large-scale production exceeding 20,000 tons annually, with their continuous discharge characteristics meeting stable high-volume supply requirements.
Two-Stage Separation Process: A Systematic Solution for Yield Optimization
Analysis of Single-Machine Shaping Yield Bottleneck
While rotor impact equipment (APR, GyRho) can achieve 55-80% yields and classifier mill equipment 50-70%, these figures typically represent levels achievable under ideal conditions with well-pretreated raw materials in single-machine shaping. In actual production, directly feeding flaky raw material (particle size >100μm) into shaping machines for single-step spheroidization presents the following inherent contradictions:
- Force Incompatibility: Large particles require high impact force for crushing and curling, but high impact forces cause excessive crushing of fine particles, generating substantial fines.
- Low Classification Efficiency: Wide raw material particle size distribution makes precise separation difficult for classification systems during mixed processing.
- High Equipment Load: Shaping machines must handle both coarse grinding and finishing functions, accelerating equipment wear.
Technical Principles of Two-Stage Separation Process
The two-stage separation process achieves precise force control and significant fines reduction by completely separating the grinding and shaping stages:
First Stage: Dedicated Grinding Phase
Uses dedicated pulverizing equipment such as ZD-JXM mechanical mills or ZD-HGM ring roller mills to moderately crush flaky raw material to D50: 21-25μm. According to Hosokawa process guidelines, pre-grinding to particle size D50: 21.8μm is the optimal feed size for spheroidization. The key in this stage is “moderate crushing”—reducing particle size to facilitate subsequent shaping while avoiding excessive impact that generates fines.
Second Stage: Precision Shaping Phase
Pre-ground narrow particle size material is fed into the ZD-ZXJ classifier shaping machine using gentle shaping mode (disc operating at low speed) for precise morphology refinement. Since feed particle size is already close to target size, the shaping machine only needs to apply minimal impact force to complete curling into spheres, drastically reducing fines generation. Simultaneously, narrow particle size distribution significantly improves classification system efficiency, allowing qualified products to be separated promptly and avoiding excessive processing from repeated cycles.
Quantitative Analysis of Yield Improvement
The two-stage separation process demonstrates significant yield improvement compared to single-machine shaping and traditional cascade:
- Single-Step Method: Classifier mill equipment directly processing flaky raw material in high-intensity mode achieves 50-70% yield.
- Two-Stage Separation Method: By separating grinding and finishing, yield increases to 60-75%.
- Traditional Cascade Method: Only 30-50% yield, serving as comparative baseline.
The advantage of the two-stage separation process lies in achieving precise force control through process segmentation. For natural graphite, using the two-stage approach to increase yield from 50% to 65% is equivalent to saving 462 kilograms of raw material per ton of finished product. At a raw material cost of 5,000 yuan/ton, this saves 2,310 yuan in raw material costs per ton of finished product.
Product Quality and Performance Characterization
The two-stage separation process not only improves yield but also enhances product quality:
- Tap Density: Typically 0.94-0.96 g/cm³, approaching theoretical optimal value.
- Particle Size Distribution: D10=11-12μm, D50=18-19μm, D90=29-30μm, with narrow and uniform distribution.
- Specific Surface Area: Typically 6-8 m²/g, moderate surface area ensuring good electrochemical performance and first-cycle coulombic efficiency.
Raw Material Adaptability Notes
Notably, the two-stage separation process shows different yield improvement effects for different raw materials. According to ALPA 2021 process research, artificial graphite, after graphitization treatment, is already relatively spherical and requires only 2-4 shaping cycles to meet standards, while natural graphite requires 8-12 shaping cycles. Therefore, when the two-stage approach is applied to artificial graphite, yield expectations exceed those for natural graphite, but this article focuses on natural graphite applications, adopting conservative 60-75% yield estimates.
For enterprises needing to process both natural and artificial graphite, the flexibility advantage of the two-stage approach becomes even more apparent: by adjusting first-stage grinding intensity and second-stage shaping parameters, optimized processing of different raw materials can be achieved on the same equipment set.
Comprehensive Equipment Performance Comparison and Selection Strategy
Comprehensive Performance Comparison
The following table comprehensively compares technical parameters and economic indicators of three mainstream spheroidization equipment types (for natural graphite):
Equipment Type | Yield | Energy Consumption | Footprint | Suitable Scale |
Rotor Impact (APR, GyRho) | 55-80% | Low | Small | 0.1-1.0 million tons/year |
Classifier Mill (Single) (ZPS, ZD-ZXJ) | 50-70% | Medium | Medium | 0.1-1.0 million tons/year |
Classifier Mill (Two-Stage) (Grinding + Finishing) | 60-75% | Medium | Smaller | 0.3-1.5 million tons/year |
Continuous Cascade (20-30 units in series) | 30-50% | Very High | Extremely Large | >2 million tons/year |
Selection Decision Framework
Anode material producers should comprehensively consider the following factors when selecting spheroidization equipment:
Production Scale and Investment Budget
- Small-scale production (0.1-0.5 million tons/year): With sufficient budget, select rotor impact (APR, GyRho) pursuing high yield and low energy consumption; prioritizing initial investment, choose classifier mill single-machine solution (such as ZD-ZXJ), simple maintenance and cost-effective.
- Medium-scale production (0.5-1.5 million tons/year): Recommend classifier mill two-stage separation approach, balancing yield and cost-effectiveness.
- Large-scale production (>2 million tons/year): Consider continuous cascade systems to meet high-volume stable supply requirements.
Raw Material Characteristics
- Natural flake graphite: Requires 8-12 shaping cycles, recommend classifier mill two-stage approach, achieving 60-75% yield.
- Artificial graphite: Requires only 2-4 shaping cycles, single-machine solution already achieves high yield.
Product Quality Requirements
- High-end power batteries: Strict requirements for particle size distribution, tap density, and specific surface area, recommend rotor impact (APR, GyRho) or two-stage separation approach.
Economic Analysis
Yield is the core economic indicator for spheroidization processes. For example, with annual production of 0.5 million tons of spherical graphite, a 50% yield solution requires 1 million tons of raw material; while a 65% yield two-stage approach requires only 7,692 tons, saving 2,308 tons. At a raw material cost of 5,000 yuan/ton, this saves 11.54 million yuan in annual raw material costs, significantly improving project economics.
Technology Development Trends
As the lithium-ion battery industry rapidly develops, spheroidization technology is evolving in the following directions:
Equipment Intelligence
By integrating online particle size analysis, tap density monitoring, and other sensors, automatic optimization of process parameters and real-time quality control are achieved, reducing manual intervention and improving batch-to-batch stability.
Fines Recovery and Reuse
Fines generated during spheroidization (<10μm) are traditionally treated as waste. According to ScienceDirect 2022 research, through re-agglomeration and pitch coating technology, fines can be recovered and reused, further improving comprehensive yield and reducing environmental burden.
Green Low-Carbon Processes
Under the carbon neutrality context, developing low-energy consumption, low-carbon emission spheroidization processes has become industry consensus. The two-stage separation approach demonstrates clear advantages in reducing carbon footprint through minimizing ineffective processing and improving equipment utilization.
Cross-Material Platform Development
Future spheroidization equipment will increasingly emphasize flexibility and versatility, achieving efficient processing capabilities for natural graphite, artificial graphite, and novel anode materials (such as silicon-carbon composites) on the same platform through modular design and adjustable parameter systems.
Conclusion
Spheroidization is a critical process in natural graphite anode material production, with equipment selection directly impacting enterprise cost competitiveness and product quality. Through systematic comparison of airflow impact and mechanical impact technical approaches, this article reaches the following main conclusions:
- Mechanical impact represents the mainstream technology for graphite spheroidization, with rotor impact (such as Alpine APR, NETZSCH GyRho) offering advantages of 55-80% high yield, short cycle, and low energy consumption, suitable for small to medium-scale production (0.1-1.0 million tons/year); classifier mill equipment demonstrates competitiveness in cost-effectiveness and flexibility through integrated design, intelligent circulation finishing, and dual system independent drive.
- Two-stage separation process (grinding + finishing) represents a systematic solution for yield optimization. By completely separating coarse grinding and finishing stages to achieve precise force control, natural graphite yield can be increased from 50-70% to 60-75%, saving 40-60% of raw materials compared to traditional cascade systems (30-50%).
- Equipment selection should comprehensively consider production scale, raw material characteristics, product requirements, and economics. Small-scale production can choose rotor impact or classifier mill single-machine solutions based on budget, medium-scale production should adopt two-stage separation approach, and large-scale production can consider continuous cascade systems.
Looking forward, with continued growth in lithium-ion battery demand and increasingly stringent environmental requirements, spheroidization technology will develop toward intelligence, green operation, and platform integration. Yield optimization is not only key to cost reduction but also the necessary path for promoting sustainable development of the anode material industry.