'Rocky Miller' - Met Detective


Case File: Investigate the use of abrasion resistant materials in centrifugal gravity concentrators

Facts: 

• In 1978, the first production-scale Knelson Concentrator was manufactured and put into service at a placer mine in Canada's Yukon Territory.
  
• The heart of the machine, the concentrate cone, was orginally fabricated from carbon steel and later from stainless-steel.
  
• The combination of enhanced gravitational force and abrasive slurry quickly created significant wear on the concentrating cone
  
• Although the fabricated steel cone lasted for only several months, its proved beyond any doubt the superiority of the Knelson Concentrator to recover gold particles across a broad size range far beyond any other gravity device available.
  
• It also started Byron Knelson, the machine's inventor, on a long journey to find the best wear resistant materials that would extend the life of the concentrate cone.
  
• His first solution was to have the concentrating cone fabricated from an abrasion-resistant (AR) steel alloy. The AR steel stood-up much better than the carbon steel it became the construction material of choice for the next 5 years.
  
• However, in 1984 the Knelson Concentrator began to make in-roads into the hardrock mining industry where the duty requirements were much more rigorous. Unlike the seasonal Canadian placer mining operations where the first Knelson Concentrators were installed, hard rock mines operate 24/7/365. Once again the abrasion issue raied its ugly head.
  
• In 1985, a new potential solution presented itself - polyurethane. Initially test coupons were attached in the high wear areas of the concentrate cone and the impact zone of tailings launder. After an extensive field test, the product was deemed a major technical success.
  
   
  
   
  
  
• Armed with the knowledge that urethane had demonstrated dramatically abrasion resistance, Byron Knelson made the decision to fund the development of a complete line of concentrate cone molds that would provide Knelson customers with the best wear resistant product available.
  
  
  
  
  
• By the end of 1986, the complete line of Knelson Concentrators were being produced with urethane concentrate cones.
  
   
  
  Closing Statement:
  
  In 1985, seven years after the first Knelson Concentrator was produced with a fabricated steel cone, Knelson pioneered the use of highly wear resistant polyurethane in centrifugal gravity concentrators. During the ensuing 24 years, many "copy-cat" centrifugal concentrators have surfaced all of which, just like the first Knelson, have used fabricate steel concentrating cones and all of which have been plagued with the same pre-mature wear issues.
  
  After an exhaustive search for a solution that would dramatically extend the life of the concentrate cone, the solution for Knelson involved a significant financial investment in molds and tooling in order to produce the best available solution-cast polyurethane concentrating cones.
  
  Verdict:
  
  Knelson has pioneered the development and application of wear resistant materials in centrifugal concentrators and in doing so has become the industry standard both in terms of wear life and metallurgical efficiency.
  
  Case closed.