Key Takeaways & Executive Findings
- •• Moderately reducing the unloading orifice size significantly enhances ore pulverization and increases fine particle yield in gas rapid unloading (GRU). • Smaller orifices improve pulverization by increasing jet speed, reducing pressure drop, and creating a larger pressure difference across the orifice. • The optimal orifice size depends on feed size to ensure efficient ore discharge and maximize grinding efficiency. • Reducing orifice size improves GRU energy efficiency, providing design guidance for industrial-scale ore discharge ports.
Abstract
Gas rapid unloading (GRU) is an innovative technology for ore comminution. Increasing the production of fine powder in each ore grinding cycle is vital for scaling up the GRU method to industrial applications. This study utilizes laboratory experiments to demonstrate that moderately reducing the orifice size significantly enhances pulverization and increases fine particle yield. Numerical simulations suggest that smaller orifices improve pulverization by increasing jet speed, reducing pressure drop, and creating a larger pressure difference inside and outside the unloading orifice. The orifice size should be optimized based on feed size to ensure efficient ore discharge. Reducing the unloading orifice size improves GRU grinding efficiency and energy use, offering guidance for the design of ore discharge ports in future industrial-scale equipment.
1. Introduction
Mineral resources are fundamental to modern human society. Ore comminution stands at the upstream of current industrial systems. Most ores, except coastal sand mines, must undergo comminution before subsequent sorting and industrial applications. Since the Paris Agreement was adopted in 2016, over 195 countries and regions (including the European Union) have committed to it, energy conservation and emission reduction have become global imperatives. Thus, ore grinding faces new opportunities and challenges in meeting current economic and environmental needs.
Over the past 40 years, significant developments in traditional mechanical grinding technology can be summarized as follows: equipment scaling, the introduction of new materials, the development of new equipment, and the application of intelligent control. However, ore comminution remains an energy-intensive process, consuming up to 4% of global electrical energy. The predominant method for ore comminution involves multistage crushing and ball milling. Although ball mills offer advantages, such as high processing capacity and continuous production, their energy conversion efficiency typically ranges from 1% to 2%. High-pressure grinding rolls (HPGR) are a notable innovation in mechanical grinding, offering high efficiency, energy savings, and significant improvements in mineral liberation. However, the inherent boundary effects during grinding have not been fully resolved. Stirred mills, such as Vertimill and IsaMill, offer significant advantages in fine grinding by providing better mixing of grinding media, with 30%–50% lower energy consumption. As a result, stirred mills show a significant cost advantage in fine grinding applications and could gradually replace ball mills in coarse particle grinding. Meanwhile, nonmechanical methods, such as high-voltage pulses, high-pressure water jets, radio-frequency technology, and microwave pretreatment, offer promising alternatives but remain limited in scalability and industrial application.
Gas rapid unloading (GRU) is an innovative nonmechanical ore comminution method. The GRU technique involves injecting high-pressure gas into the ore and rapidly decompressing it to induce tensile failure, pulverizing the ore into micrometer-sized particles within milliseconds. Studies have confirmed the feasibility and versatility of GRU for ore comminution. Compared with traditional grinding methods, this technique achieves rapid pulverization with a single gas unloading cycle in milliseconds, eliminating multiple grinding stages and reducing processing time. Ore has a high compressive strength but low tensile strength, and the energy required for tensile failure is only one-tenth of that required for compressive failure. It utilizes high-pressure gas decompression to induce ore tensile failure from within, theoretically consuming less energy. The comminution mechanisms of several comminution machines are shown in Table 1. Fig. 1 illustrates the mechanism by which the GRU induces ore pulverization. Meanwhile, GRU utilizes gas as the working medium, eliminating the need for grinding media, such as steel balls, and minimizing material wear. In addition, this method shows consistent performance across different ore sizes without significant size effects.
Loading authentic research manuscript (Pages 1–5)...
Genghao Zhang, Deyang Zhao, Yi Chang, Yongbo Fan, Renshu Yang, Shihai Li (2025). Influence of unloading orifice size on the production of microsized ore particles by gas rapid unloading. Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报). https://doi.org/10.1007/s12613-024-3085-3
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is gas rapid unloading (GRU) and how does it work?
Gas rapid unloading (GRU) is an innovative nonmechanical ore comminution method that injects high-pressure gas into ore and rapidly decompresses it to induce tensile failure, pulverizing the ore into micrometer-sized particles within milliseconds. It exploits the low tensile strength of ores compared to compressive strength, theoretically consuming less energy than traditional mechanical grinding.
How does the unloading orifice size affect ore pulverization in GRU?
The study found that moderately reducing the orifice size significantly enhances pulverization and increases fine particle yield. Numerical simulations indicate that smaller orifices increase jet speed, reduce pressure drop, and create a larger pressure difference inside and outside the orifice, all contributing to improved grinding efficiency.
What are the practical implications of this research for industrial ore grinding?
The findings provide guidance for designing ore discharge ports in future industrial-scale GRU equipment. Optimizing orifice size based on feed size can improve grinding efficiency and energy use, potentially reducing the energy-intensive nature of ore comminution and supporting global energy conservation efforts.
What methods were used in this study?
The study utilized laboratory experiments to demonstrate the effect of orifice size on pulverization and fine particle yield, complemented by numerical simulations to understand the underlying mechanisms, such as jet speed and pressure differentials.
What are the advantages of GRU compared to traditional grinding methods?
GRU offers rapid pulverization in milliseconds, eliminates multiple grinding stages, reduces processing time, and consumes less energy by inducing tensile failure rather than compressive failure. It also eliminates the need for grinding media, reducing wear and material contamination.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.