Cyanidation Batch Tests

At the beginning of the project is important to evaluate different processes to recover gold and one of the most employed processes is cyanidation. Preliminary tests are often necessary to evaluate whether a given gold ore is at all suitable for cyanidation treatment. The first test may imitate the extreme limits to which such treatment could be performed at industrial scale. Metallurgists have an important participation during the development of cyanidation testing programs and explaining the results. The testing program can include simple or complex tests that must be done by an experienced technician who must follow specific procedures and also must be able to detect problems and provide solutions. Most the time, the results and conclusions must be analyzed by the metallurgist and his opinion has a direct influence in the development of the project. This point could have some discrepancies if the results are different in relation to the expected results. There are some aspects to consider at the moment of analyzing all cyanidation tests results:

·         If cyanidation tests were done under conditions very specific, the possible application of these results must be reviewed carefully. For example, sometimes is not evaluated the effect of water on gold dissolution and probably the water to be employed in the operation has dissolved ions that could affect the process.

·         The sample preparation procedure is important. The metallurgist balance indicated if the sample was well prepared or not. The balance compares calculated head vs assayed head. If there is significative difference, the metallurgist has to ask for the sample preparation procedure. It is important to mention that real cyanidation tests include assays for gold and silver on pregnant liquid solution and leaching residue.

·         If the results are excellent, will be necessary consider the factors that could affect the process (e.g. pH, pulp density, temperature). Tests have some restrictions that must be considered at the moment of designing a plant. Since cyanidation tests give a first idea of the amenability of gold ore to cyanidation, the metallurgist must study the factors that could affect the application of the process at industrial scale.

·         There are some limitations and restriction to consider. See next table,