The mechanism of radial airflow in enhancing dry high-gradient magnetic separation

Abstract

In our previous study, a novel pneumatic magnetic separator that integrates radial airflow was introduced to address the challenge of low separation efficiency due to particle agglomeration during dry high-gradient magnetic separation (dry HGMS) of powder materials. However, the specific mechanisms of airflow remain inadequately understood. In the present study, a specially designed radial airflow matrix was employed to perform visualization separation experiments and conduct CFD-DEM simulations for various airflow configurations in dry HGMS. Results indicate that mixed ore particles sized −0.038+0.013 mm cannot easily overcome adhesion-related challenges when separation depends solely on gravity feed. The use of airflow feed increases the TFe grade of material accumulated on the matrix surface from 49.48% to 56.59%. When radial airflow is introduced, the maximum TFe grade reaches 69.01%. A comparative analysis of the simulation results indicates that when the TFe grade of the accumulations is around 61%, the corresponding recoveries are 59.47%, 65.42%, and 86.36% for airflow feed alone, gravity feed coupled with radial airflow, and airflow feed coupled with radial airflow, respectively. Furthermore, when the TFe grade of the concentrate is around 65%, the corresponding recoveries are 36.75%, 59.82%, and 60.53% under the same operating conditions. The application of radial airflow effectively promotes the dispersion of powder materials, dislodges adhered quartz particles, and significantly enhances selectivity. Thus, it achieves better separation performance than the traditional airflow feed methods.