An Investigation of Ammonium Nitrate Loss to Mine Discharge Water at Diavik Diamond Mines

An investigation was carried out at Diavik Diamond Mines Inc (DDMI) to identify and quantify the mechanisms through which ammonium nitrate (AN) was entering the mine discharge water. The goal was to develop and complete an investigation of the potential AN loss mechanisms in order to assess their contribution to ammonia in the mine water system. The initial phase of the project involved the collection and analysis of blasting and water quality data that were used to determine the mechanisms by which the ammonia enters the mine water system and to establish a baseline data set for comparison with results from future trials designed to reduce AN loss. Three potential options for reducing AN loss were identified through the first phase of the project. The second phase of the project involved conducting a series of monitored trials with changes made to the drilling and blasting process. The results of these trials were compared to the baseline data set to determine if the changes introduced for the trials had reduced AN losses while producing satisfactory blast results. This paper describes the process for the collection of the baseline data, provides an analysis of the resulting data, discusses the changes made to blasting operations in order to minimise AN loss and describes the results observed subsequent to these changes.