Transfer Chute Plugging Solved at Iron Ore Export Terminal
A major iron ore exporter in South Africa was experiencing major delays in the material loading operation created by flow stoppages. This disrupted schedules, leading to higher shipping costs. A key right-angle transfer chute in the process had to handle iron ore at 10,000 TPH.
The facility experienced severe plugging problems with this chute that feeds into their main iron ore handling system. Iron ore plugging would occur several times per shift, requiring operators to use high pressure water hoses to unplug the chute. At times, the iron ore was bone dry and dusty, leading to severe dust generation during handling in the chute.
The iron ore is highly abrasive and would wear parts of the transfer chute that did not experience severe plugging. A rock-box design was implemented to reduce wear, but because the iron ore was cohesive at times, the chute would plug.
The combination of high belt speed (5.5 m/s), large flow rate, and hard particles would rapidly wear the steel liners in the chute. The wear was exacerbated when the iron ore was bone dry. Frequently, portions of the chute required complete replacement due to holes appearing from wear. This problem cost both time and money, due to the high cost of wear liners.
Flow testing on various samples of iron ore allowed J&J engineers to evaluate the cause of chute plugging. A thorough review of the transfer chute system was performed. It was determined that the chute design needed significant modifications to maintain reliable stream flow. Discrete element modeling (DEM) of the existing chute and new design was performed by J&J to understand the cause of plugging and what steps were necessary to prevent plugging.
A new chute geometry was developed, including a honeycomb rock-box feature on both the hood and spoon flow controlling geometries to minimize abrasive wear effects. J&J was also contracted to develop mechanical fabrication drawings and supply of the new chute, which has several key features for maintaining sticky iron ore flow. Abrasive wear testing was done by J&J to evaluate chute liner life and estimate absolute wear.
The new iron ore right-angle transfer chute has been in operation for over two years with minimal downtime for maintenance. The ceramic honeycomb micro-rock-box features have substantially reduced the abrasive wear with the iron ore. Plugging has been eliminated and belt spillage and off-tracking have been prevented. Lastly, dusting has been significantly reduced due to proper iron ore stream control during handling through the chute.