The ConSep, ACACIA Reactor is a device that utilizes a high-density cyanidation process to achieve very high, usually near total, recovery of gold form gravity concentrates.
The process utilizes a fluidized bed and a chemical oxidant to enhance the gold dissolution kinetics to the point where the bulk of the dissolution occurs in a few hours. For convenience and security, most plants operate a 24-hour turn around. The product from the process is in the form of cathode gold ready for smelting by traditional means.
The ConSep ACACIA Reactor performs a two-fold role. Firstly it increases gravity gold production, leading to a decreased CIP feed grade. Secondly, it removes slow leaching components from the plant leaching circuit. This two-fold benefit leads to the following efficiencies:
- Enhancement of the dissolution kinetics.
- Enhancement of the absorption kinetics.
- Reduction of the gold load reporting to the carbon.
- A significant reduction of the 'gold in circuit' lockup.
- Removal of slow leaching entities that can also result in a lowering of the required cyanide concentrations in the leaching circuit and a subsequent reduction in overall cyanide consumption.
The above benefits are discussed in this paper, with a particular focus on the ConSep ACACIA Reactor's role in removing slow leaching components, with data generated over a 21-month period.
Improvement in overall plant recovery via removal of slow leaching gold species is achieved in two ways.
Firstly, some of the slow leaching entities, successfully leached under intensive cyanidation, are not always fully leached under plant conditions. This results in a lowering of the solid tailing.
Secondly, the faster leaching kinetics achieved in the plant as a result of the removal of slow leaching entities, results in faster and more complete absorption of the dissolved gold onto activated carbon. This results in a lowering of the solution tailings.
The construction and operation of the ConSep ACACIA Reactor is simple. Apart from the reactor body, which is a proprietary design, all components of the system are 'off the shelf' or specific to the site's requirements. In operation of the fully automated version, a PLC controls a series of valves and pumps. Except for a daily changeover process the only operating component for the bulk of the time is a relatively small solution pump. The process can be totally automated giving the security of a 'hands-free' concentrate handling process up to the point where the product is presented as a cathode gold.
The ConSep ACACIA Reactor was developed by Anglogold Australia (formerly Acacia Resources) for Union Reef's Gold Plant and has been in production since February 1999.
It has proven to be a low cost, high recovery, mechanically reliable method for the processing of gold concentrates.
Such has been the success of the plant, as of June 2003 there are eighteen full installations of the processing plant installed at the mines owned and/or managed by Anglogold, Newmont, Placer Dome, Independence (formerly Lonrho), Sons of Gwalia and Harmony.
Download the full paper here.
Gravity Leaching with the ConSep ACACIA Reactor - Results from Anglogold, Unions Reefs
1.3 MB | 9 page Acrobat Info Sheet
