The performance of a large ore processing plant was being hampered by a big problem; apparently with its initial flotation cells. Downstream equipment was frequently fouling up with waste and the performance of the flotation cells, which initially separate the desirable product from waste material, were being blamed. Plugged nozzles at the downstream centrifuges were regularly taking units out of service for cleaning and repair.
This issue had been going on for a number of years, however, recent improvements made elsewhere in the facility had caused this processing plant to become the site bottleneck. The plant team needed a solution for nozzle plugs, now.
Focused on the flotation cells, the team had devised and implemented improved monitoring and statistical process control of all operating parameters. They found the problem ebbed and flowed over time, suggesting that the improved process control may be working, but it never seemed to abate with the consistency that would allow them to declare victory.
Each time the problem would reassert itself a post-mortem analysis was performed: Had our process controls failed? Had something else changed that was allowing excess waste material to reach the centrifuges anyway? Was there a gap somewhere in our approach to solving this problem?
Stroud was called in to help the team to reassess their efforts, with a particular focus on the problem solving approach being employed. The plant team knew that a sound approach should produce a clear root cause and an effective solution but, for whatever reason, this problem was persisting.
Retracing their steps, they re-examined the connection between nozzle plugs and flotation cell operation by closely examining the plug material itself. Each plug consisted of some desirable finished product, some waste material, and a third component, around which the plugs seemed to amass: strands of a fibrous substance, routinely referred to as “dinosaur hair”. Not literally the hairs of prehistoric beasts, but some other naturally occurring material whose ubiquity seemed to suggest that it may be inherent to the mined ore itself; an unavoidable component of the rock, formed long ago.
Unsatisfied with this explanation, the team further analyzed samples of the material only to discover that it was nylon - a man-made fibre invented less than 100 years ago. In a search of sources of nylon, the team discovered a few likely culprits including the occasional, errant disposed of PPE items, like boot covers, into process vessels like the floatation cells.
Armed with this new understanding of the problem, the behaviors around PPE disposal across site quickly changed and plugged centrifuge nozzles were virtually eliminated. The lasting wisdom for the organization was that, once fully understood, even the most seemingly complex problems can have simple solutions.
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