Heap Leach Operations Monitoring
Heap and dump leach piles are unsaturated environments and therefore heap leach management requires addressing all the complex flow conditions inherent to unsaturated zone hydrology. The two key hydrological concerns are adequate flow and even or uniform flow of solution through the heap. Adequate flow is necessary for the heap to be leached in an economical time, while uniform flow is needed to allow all the ore to be thoroughly leached.
The process requires a relatively permeable and a uniformly structured material that will not promote solution channeling or short-circuiting. Portions of the heap do not receive sufficient contact with the solution and remain unleached if solution does not flow evenly throughout the heap and instead flows preferentially through distinct paths.
Dry ore composed of many fine particles. The chemical reaction for the dissolution of gold, the "Elsner Equation", follows: 4 Au + 8 NaCN + O2 + 2H2O → 4 Na[Au(CN)2] + 4 NaOH. Applying too much solution hinders the leaching reaction. Oxygen is one of the reagents consumed during cyanidation, and a deficiency in dissolved oxygen slows leaching rate. Ideally, solution percolates through the ore by means of capillary action leaving pockets of oxygen in the pores between particles.
Process Control and Risk Management Solutions
Scanimetrics' WiTAP™ wireless sensor and MoteScan™ cloud tools provides the key capabilities (data collection, reporting, and analysis) needed for a successful heap leach process control program. The WiTAP™ wireless sensor modules can automatically acquire real-time heap leach process parameters from deep within the heap leach pile and visualize the data. The WiTAP™ Mote is a rugged wireless data collection device that has been proven to function reliably even in the harshest conditions. Our powerful, easy-to-use MoteScan™ cloud software platform transforms sensor data into information that operators, maintenance, safety, compliance, engineers and executives can use to make better decisions. Scanimetrics also provides consulting services to develop end-to-end condition monitoring solutions for your unique needs and challenges.