Silver nitrate titration has been one of the most commonly used methods in measuring free cyanide in gold leaching processes. Image yourself as a mine operator, and your task is to measure how much free cyanide is in your leaching solution to control cyanide addition. Lacking alternatives, many mine operators automatically turn to silver nitrate titration as a standard approach.
The analysis involves using silver to form stable complexes with cyanide and having either potassium iodide or rhodanine as an indicator. Once all free cyanides have formed complexes with silver, the excess silver then reacts with the rhodanine indicator resulting in a colour change from yellow to salmon pink. The point in which this colour change occurs is also called the endpoint, which then allows the operator to calculate the amount of free cyanide in the sample based on the amount silver nitrate solution added to the sample before the endpoint. The determination of the endpoint is often highly debatable as it relies on the human eye. The colour sensitivity of human eye varies not only from person to person, but it also depends on the lighting conditions of the room. As such, to achieve reliable results often means making multiple manual titrations and averaging the measurement results while sieving out erroneous measurements. On average, each titration procedure takes 15-30 minutes, and that excludes time needed to clean and set up the titration apparatus and also prepare the sample.
Challenges to silver nitrate titration are not limited to the scenario described above. As such, we have developed a plug-and-play solution that can help mine operators get fast and reliable measurements for gold cyanidation. To fully understand how our solution enables users to mitigate every challenge in this process, we made a comparison table in the following: