A carbon absorption, desorption and regeneration (ADR) plant supplied by FLSmidth for Shanta’s New Luika Gold Mine in south west Tanzania
A carbon absorption, desorption and regeneration (ADR) plant supplied by FLSmidth for Shanta’s New Luika Gold Mine in south west Tanzania

An Absorption, Desorption and Refining (ADR) plant supplied by FLSmidth has allowed Shanta Mining Company Limited (SMCL) to boost its gold and silver recovery at the New Luika Gold Mine in south west Tanzania. Dave Capstick, Business Development Manager at FLSmidth, says the 2t ADR plant has resulted in an increased carbon throughput to the Carbon in Leach (CIL) circuit at New Luika from 20t a month to 80t at present.

The ADR plant comprises an acid wash, a Zadra strip circuit with an FLSmidth designed heater skid, an electrowinning circuit and a carbon regeneration kiln, in addition to ancillary equipment such as pumps, screens and tanks for carbon handling. “All the equipment was designed and manufactured by FLSmidth. It was shipped, installed and commissioned jointly by our South African and Salt Lake offices” Capstick says. Commissioning took place in the second quarter of 2014.

Initial results from the new plant point to an improvement in gold recovery of two percentage points, while silver recovery has tripled. The benefits of the new ADR plant were apparent at an early stage, and the ADR plant was an important step in the debottlenecking of the gold/silver recovery process.

The ADR plant forms part of FLSmidth’s offering of gold recovery equipment. The strip circuit in particular consistently delivers stripping times of between eight to nine hours. “Given the rise in energy costs, our improved heater skid designs have resulted in significant power savings for the end user compared to competitor designs.” Capstick points to a recent field case study that highlighted heat recoveries of about 90%.

“Our electrowinning cells with basketless cathodes carry a patented in-cell washing design that reduces cathode washing time and eliminates the need to remove the cathodes from the cell for washing.” Capstick adds that FLSmidth’s carbon regeneration kiln has a patented sealing arrangement that avoids air entering the kiln. “The kiln also features a robust design to avoid warping, which otherwise results in kiln misalignment and operational inefficiencies.”

Wally Channon, Technical Manager at SMCL, says: “The ADR plant at our New Luika Mine has already exceeded the design performance target and removed the previous bottleneck to increased process plant throughput.”

Looking to the future, Capstick says that FLSmidth has also supplied spares for the ADR plant. “We are able to offer various combinations of maintenance and operational contracts to assist our clients in specific areas. FLSmidth works closely with its clients to assist with the optimisation of existing operations. We work as a partner to help our clients reduce their operating costs on an ongoing basis. This ‘One Source’ approach becomes even more effective when there is a large quantity of FLSmidth equipment on site.”

Capstick concludes that the success of the ADR plant at New Luika Gold Mine has generated interest in FLSmidth’s gold recovery equipment from other African mining clients. “The success of the ADR plant is a powerful statement in and of itself. The client is very pleased with the end results, and thus New Luika is an important reference base for FLSmidth.”

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