Unearthed Perth 201813 Apr - 15 Apr
From Idea to Prototype on Resource Challenges in just a Weekend
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Challenge 2 - Refinery
Strong and Steady - using lab analysis for regulating leach recovery process
Lead Mentor: Trevor Bilney , Production Process Control and Improvement Superintendent
The Nickel West Refinery processes high grade nickel matte via an ammonia leach circuit prior to purification of leached material into high purity nickel products.
The leach circuit at NKW comprises of 6 leach autoclaves configured as 2 first stage, 3 second stage and 1 third stage leach claves.
The leach process is controlled predominantly via operator response to Laboratory assays (results). These responses can be quite variable and inconsistent causing the following key issues:
the operating cost in the area is high due to overuse of key inputs (air and ammonia)
the instability of the product from the leach area causes instability and production loss in the downstream areas of the plant.
The circuit is fed ground nickel matte in slurry form to which amsul containing liquor, anhydrous ammonia and air are added to extract nickel from the matte.
Solid and liquor samples are collected from the leach circuit every 2 to 12 hours (depending on location) and analyzed in the lab for Nickel, Copper, Cobalt, Iron, Ammonia and Amsul (ammonium sulphate). From these lab results, the process technician must evaluate the assays and change the process conditions to ensure that key variables are maintained on spec.
In addition, the operator must control flow rates around the plant to ensure inventory levels area maintained and equipment is not under utilized or overfed at an time.
Operator response to lab assays and changes made to process can be quite variable from person to person and therefore the leach process is quite unstable in the key areas of Ammonia consumption, Air Addition, Flow Rates and Nickel, Cobalt and Copper Recovery.
Impact and Value
Previous studies in this area have highlighted a $2-3M opportunity for consumable cost reduction in this area, much of which remains unrealised.
Can a system be established to enable consistent decision making?
Is there one or more variable that causes process instability?
A laboratory upgrade is underway which will enable samples to be analysed at least every 2 hours,. how can this information be used?
Data and Data Dictionary will be released on Friday night.
Operating data in 1hr averages since May 2016 since last signifiant process change.
- Schematics, P&IDs and flowsheets for the system.
- Production loss data from leach area
- Existing condition monitoring model and data