Bret Boster - Country Manager, Argentina explains the benefits of the Cyanide Destruction Circuit at Manantial Espejo.
When was the cyanide destruction plant started and what are the benefits of the new cyanide destruction circuit at Manantial Espejo for the environment and our operations?
The Manantial Espejo cyanide destruction plant began operations in December 2008 and we started using solid Sodium Metabisulfite powder (SMB) as the active reagent. Soon after Manantial Espejo started operation we were inspecting the SMB powder preparation area and the tank for reagent preparations. Seeing the leftover big bags and some SMB that had solidified and become useless, and after hearing the complaints of the plant operators we wondered if we could improve the process. We investigated alternative reagents and evaluated their safety, environmental and economic performance. The automatic liquid sulfur dioxide dosing system we decided to install as a result of this analysis removed the need for operators to prepare the reagents, which improved the safety of the plant. The need for operator intervention was reduced and the automatic system improved control of the cyanide destruction reaction, which simplifies compliance with our strict internal environmental standards. The waste generated by SMB packaging was also eliminated.
How does the new system work? Is it a success?
SMB (Na2S2O5) is a source of sulfur dioxide, which is necessary for the cyanide destruction process, however only 65% of the SMB reagent produces sulfur dioxide. The liquid system allows us to replace the SMB with 100% sulfur dioxide. Like all new systems we had some minor hiccups in the commissioning and transition phases. We brought in a specialist to assist with fine-tuning the chemistry of the cyanide destruction reaction in that period. Today the system is functioning well and we are achieving efficient cyanide destruction before the tailings leave the plant. It has been a successful project for us.
Are there any future refinements to the system planned?
Once we got the new process running, we asked ourselves can we optimize it? So that’s what we are doing now, we are investing US$800,000 to install our own sulfur dioxide storage tanks, an improved winterized dosing system, and an additional reactor to provide additional cyanide destruction capacity. The improved system has some new technology designed by our Manager of Projects, Javier Oberholzer and his engineers. The system will be up and running during the second half of 2012. No doubt when we are finished we will be asking ourselves again can we do this better?