3. Yankuang Energy Group Co. , Ltd. , Jinan 250014, China；

4. Xinwen Mining Group Co. , Ltd. , Tai’an 271219, China

Abstract

Objective To address the problems associated with mineral separation beds under single-frequency pulsed airflow， including non-uniform fluidization， aggravated local particle back-mixing， reduced separation accuracy， and high energy consumption， as well as the shortcomings of the traditional steady-state air dense medium fluidized bed， i.e.， large bed density gradients and severe back-mixing of fine particles， a dual-frequency pulsating airflow design is proposed. Through the nonlinear coupling of high- and low-frequency airflow， the design optimizes bed fluidization state， aiming to improve the dynamic regulation accuracy of separation density and reduce operational energy consumption.

Methods A method combining numerical simulations of computational particle fluid dynamics and theoretical derivation was adopted. Based on the Barracuda software and the Euler-Lagrange method， the Wen-Yu drag model was adopted to construct a cuboid fluidized bed model with dimensions of 0.3 m×0.3 m×0.6 m. Magnetite powder was used as the fluidizing medium， and coal and gangue of 1 mm particle size were used as the material for separation. The fluidization characteristics under three airflow conditions （non-pulsation， 4 Hz single-frequency pulsation， and 4 Hz+20 Hz dual-frequency coupled pulsation） were compared. The expression of the dual-frequency pulsating velocity field was derived. A method for determining the critical frequency based on equivalent relaxation time was established， and the principle of amplitude optimization and a model determining the optimal amplitude ratio based on the separation potential difference were established.

Results and Discussion The results showed that dual-frequency pulsation effectively increased bed activity， reduced particle size segregation between coarse and fine particles， and improved particle mixing uniformity. Pulsation energy had no significant effect on the overall average bed density. However， under dual-frequency pulsation， the standard deviation of axial particle density fluctuations decreased by approximately 32 compared with other conditions. Meanwhile， the axial static pressure gradient decreased， resulting in a more uniform density distribution. During the mineral stratification process， dual-frequency pulsation accelerated the directional settling rate of the minerals to be separated. Within 50 s， the gangue penetration amount approached 0.045 kg， which was higher than 0.01 kg under the non-pulsation condition and 0.025 kg under the single-frequency pulsation condition， indicating better stratification sufficiency.

Conclusion The nonlinear coupling of high- and low-frequency airflow can effectively compensate for the limitations of single-frequency pulsation and alleviate the particle segregation problem in traditional fluidization by exciting high-order vortex structures in the bed. Dual-frequency pulsation does not change the macroscopic average density of the bed， but it can make the density distribution more uniform along the bed height， providing a more stable environment for the density-sensitive separation process. At the same time， it accelerates the process of density-based particle separation， improves product recovery efficiency， and achieves higher dynamic regulation accuracy of separation density and lower energy consumption. This can provide a reference for subsequent research on the dynamic control of gas-solid two-phase flow and dry beneficiation of complex minerals.

Keywords： dry beneficiation； fluidized bed； dual-frequency pulsation； particle density； fluidization characteristics

Get Citation：Gao Zhonglin， Xie Han， Gao Hang， et al. Numerical simulation of fluidization characteristics and particle motion behavior in a dual-frequency pulsating fluidized bed［J］. China Powder Science and Technology， 2026， 32（4）： 54-62.

Received：2025-12-01， Revised： 2026-05-25，Online： 2026-06-16.

Funding：The research was supported by Anhui University of Science and Technology Talent Introduction Fund (Grant No. 2023yjrc05) and the National Natural Science Foundation of China (Grant No. 52304279).

DOI：10.13732/j.issn.1008-5548.2026.04.003

CLC No.：TD028.8；TB44

Type Code：A

Serial No.：1008-5548（2026）04-0054-09