Advanced Comminution Circuit Control at Toka Tindung Gold and Silver Processing Plant

Michael Walshe

Outotec Pty Ltd

In the rolling foothills above the coastal city of Manado, North Sulawesi, Indonesia, lies the Toka Tindung gold and silver processing plant, at an elevation of approximately 200m above sea level. The Toka Tindung project, which commenced operation in January 2011 and poured its first gold dore bar the following April, is 100% owned by PT Archi Indonesia (Archi), one of South-East Asia’s largest independent gold producers.

At the processing plant, the primarily oxide-based gold ore is processed into bullion using comminution processes (crushing and grinding), followed by carbon-in-leach (CIL) extraction, elution and finally smelting, to produce dore bars. The bars are then sent to the Mulia Refinery in Jakarta, to be refined into 99.99% purity gold.

The plant has steadily increased its production since 2011.   In recent times, additional milling capacity was installed as part of an expansion project to push production targets even further.  To support a fast production ramp-up period and ultimately optimise the overall plant performance, an advanced process control solution was implemented on the comminution circuit by Outotec, in collaboration with Archi. The advanced process control system consists of ‘intelligent’ sensing instruments that provide online dynamic information to a high-level control system. The system interprets this data and makes ‘intelligent’ control actions that should ultimately maximize throughput and energy efficiency and ensure an optimal particle size distribution is maintained with minimal fluctuations to downstream processing.

This paper discusses the challenges, successes and future opportunities associated with this advanced comminution control system at Toka Tindung, with particular attention paid to the metallurgical performance, plant stability and reliability outcomes.

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