Optimizing rice bran ball milling via a friction-coupled population balance model: Integrating comminution theory and energy efficiency--颗粒学报PARTICUOLOGY

Laboratory of Food Materials and Structure, Food Engineering Department, Federal University of Campina Grande, Campina Grande, Paraiba, B58429-900, Brazil

10.1016/j.partic.2025.07.013

Volume 105, October 2025, Pages 36-50

Received 24 May 2025, Revised 11 July 2025, Accepted 16 July 2025, Available online 24 July 2025, Version of Record 30 July 2025.

E-mail: hugo.miguel@professor.ufcg.edu.br

Highlights

• Friction-coupled PBM clarifies net breakage energy for efficient rice bran milling.

• Early fragmentation transitions to a fine-dominated regime with slower comminution.

• Short, high-speed milling yields moderate fineness at lower energy consumption.

• Extended milling achieves sub-5 μm sizes but at steep power penalties near 5 kWh/ton.

• Friction-aware PBM surpasses classical laws, enabling robust milling optimization.

Abstract

Despite rice bran's considerable nutritional and functional potential, its fibrous structure and high oil content complicate efforts to produce uniform, finely milled powders for food and nutraceutical applications. This study addresses that challenge by examining how milling time (30–90 min) and rotational speed (30–120 rpm) influence both the extent of particle size reduction and the associated energy demand. A laboratory ball mill was used to generate a broad range of operating conditions, while mechanical energy usage and particle-size parameters (d₁₀, d₅₀, d₉₀) were recorded. Population Balance Modeling (PBM) served as the primary analytical framework, calibrated through experimental size distributions to yield breakage kinetics. Frictional effects were incorporated to determine net breakage energy, and classical comminution laws (Bond, Rittinger, Kick) were also evaluated for benchmarking. Results revealed two key milling regimes: an early stage with rapid fragmentation of larger particles, followed by a fine-dominated phase marked by diminished breakage rates and agglomeration. Friction-coupled PBM simulations achieved near-unity parity with experimental data, significantly improving upon simplistic energy models. Short, high-speed milling (e.g., 30 min at 120 rpm) delivered moderate fineness (d₅₀ ≈ 70–90 μm) at relatively low energy (≈0.002–0.005 kWh/ton), whereas prolonged milling (≥90 min) could push median sizes below 5 μm but escalated energy consumption (∼5 kWh/ton). These findings highlight the trade-off between achieving ultra-fine bran and managing rising power costs. By integrating friction-coupled PBM insights with empirical measurements, the study provides a rigorous basis for multi-objective process optimization, guiding industrial-scale rice bran milling toward both enhanced product quality and improved energy efficiency.

Graphical abstract

Keywords

Energy consumption; Particle size reduction; Bond–Rittinger–Kick; Multi-objective optimization; Milling efficiency

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