Towards Solving the Complexity Associated with Continuous Countercurrent Decantation (CCD) System in Solid–Liquid Separation Processes

Continuous countercurrent decantation (CCD) washing is an important unit operation employed mostly in hydrometallurgical, mining, and chemical process industries. In many of the hydrometallurgical processes CCD system is used in combination with leaching circuit. It is observed that while obtaining the number of CCD stages, water and material balance the work becomes very cumbersome and time consuming. In this work simple equations are developed to overcome the above complexity of CCD system. The equations developed were utilised to find the numbers of CCD stages, the solute concentrations at various stages, final solute concentration and wash solution requirement, etc. The unreacted solid passes through subsequent stages unhindered and rejected along with reject solute solution. The equilibrium model equations can be utilised for both combined and standalone CCD circuits. Case studies are included to check the validity of the model equations under different operating conditions. The work has been carried out specifically for hydrometallurgical operations where concentrated leach solution can be generated from very lean ore.