Design, Fabrication and Performance Evaluation of A Laboratory Hammer Mill for Different Types of Rock

In this research, a laboratory hammer mill was designed using AutoCAD software, and constructed by shielded Metal Arc Welding technique, followed by performance evaluation. The output crushing force of 23 kN and average crushing strength of 12 kN/mm2 were achieved. The feed crushing performance of granite rock, quartzite rock, and limestone rock range from 340 kg/hr, 359.2 kg/hr and 384 kg/hr respectively. All the components of the machine such as the hammers, hammer discs, shaft, pulley drive, belt drive and machine casing were designed and constructed from locally sourced materials. The hammers which are normally made from manganese steel is scarce locally, hence, the hammer used in this work has been made based on improvisation of readily available spring steel materials to reduce cost. A mild steel shaft of Φ70 mm, 495 mm long made of mild steel were machined using lathe machine down to Φ50 mm, 489 mm long. The power rating of the machine was determined to be 4.0 kW (5.3 Hp) electric motor requiring 415 volts and 50 Hz frequency. Three (3) different types of rocks (igneous, metamorphic and sedimentary) were used to evaluate the performance evaluation of the fabricated hammer mill, efficiency of 85.2%, 88.9 % and 96% of granite, quartzite, and limestone respectively were achieved.