FINLAND – Outotec has developed a two-stage partial roasting process to remove impurities such as arsenic, antimony and carbon from copper and gold concentrates as a pre-treatment to actual extraction processes. The process is being installed at Codelco’s Mina Ministro Hales mine in Chile where it will remove more than 90% of the arsenic in concentrate.
The partial roasting process for copper concentrates is a single-stage process. The impurities are volatilized and the process produces calcine, which is rich in copper sulphide but has a low impurity content. The calcine is mixed and can be further processed in copper smelters. The partial roasting process is also combined with post-combustion of process gas to convert all volatile compounds into oxides.
The roasting process for refractory gold concentrates contaminated with arsenic and carbon is a two-stage process. Arsenic is removed in the first roasting stage while carbon and remaining sulphur are removed in the second stage. All sulphur, iron and carbon are fully oxidized in the process and calcine suitable for actual gold leaching is produced.
Outotec has also established a new continuous pilot plant at the company’s research center in Frankfurt, Germany, to test customers’ concentrates with the new process. During the tests it is possible to collect reliable and necessary data for industrial process scale-up.
For more information, please contact Outotec chief technology officer Kari Knuutila by phone at 358-20-529-2009 or cell 358-40-779-9566. You may also visit www.Outotec.com.