Multi-Channel Parallel High-Voltage Power Supplies for Electrostatic Ore Separation
Electrostatic separation of minerals relies on differential charging and deflection of particles in high-electric-field environments, where modern plants process thousands of tons per hour using drum or free-fall separators requiring tens of kilovolts across multiple electrodes simultaneously. Multi-channel parallel high-voltage systems have emerged as the enabling architecture that delivers independent, precisely regulated outputs to each separation stage while maintaining overall system efficiency and reliability under the harsh conditions of mining environments.
Each separation channel typically operates between 20 and 60 kV at currents ranging from microamperes during dry periods to several milliamperes when mineral conductivity rises with humidity or surface contamination. Parallel architecture employs a common intermediate DC bus fed by a single high-power rectifier, with individual channels using compact resonant inverters driving dedicated high-frequency transformers and Cockcroft-Walton multiplier stacks. This configuration achieves greater than 94 % end-to-end efficiency by minimizing I²R losses in shared cabling while allowing per-channel regulation to within ±50 V even during rapid load swings caused by particle cloud density changes.
Active current sharing among channels is implemented through droop-free digital control loops that monitor output current at the multiplier level and adjust inverter phase shift in sub-microsecond increments. This prevents any single channel from hogging current when a conductive particle stream momentarily bridges electrodes, a phenomenon that previously caused voltage collapse across entire separator decks. The result is sustained corona current stability better than 2 % across all channels even when individual loads vary by more than 10:1.
Arc management employs a two-tier strategy: fast local quenching at the channel level using solid-state crowbar circuits that collapse output in under 8 µs, followed by coordinated global recovery where the master controller sequences re-energization of affected channels with deliberate 50-100 ms delays to prevent sympathetic re-arcing. This has reduced arc-induced downtime by more than 90 % compared to monolithic supplies that required complete system shutdown.
Dust ingress and high humidity typical of mineral processing plants necessitate fully potted multiplier assemblies using cycloaliphatic epoxy formulations that maintain partial discharge inception voltage above 70 kV after prolonged exposure to 95 % relative humidity and silica dust loading. Oil-free design eliminates the leakage and fire risks associated with traditional liquid-immersed systems while simplifying maintenance in remote locations.
Channel-to-channel isolation exceeds 100 MΩ at operating voltage through optical coupling of all control signals and floating fiber-optic current monitoring, preventing ground loops that previously propagated faults across the entire separator when a single electrode contacted the grounded rotor. Remote monitoring via industrial Ethernet allows real-time visualization of corona current profiles for each separation stage, enabling operators to optimize feed rate and electrode spacing dynamically for varying ore mineralogy.
Modular construction permits capacity expansion by adding identical channel modules to the common bus without system redesign. A typical 24-channel system can be upgraded to 36 channels in a single shift by inserting additional multiplier cassettes and updating the master controller firmware, providing unprecedented scalability for plants processing complex polymetallic ores.
Energy recovery during electrode discharge events returns greater than 85 % of stored capacitive energy to the DC bus through synchronous rectification, reducing net consumption particularly during processing of high-conductivity sulfide minerals that trigger frequent quenching cycles, these parallel architectures routinely achieve greater than 99.7 % online availability while delivering separation efficiencies that recover several additional percentage points of valuable mineral compared to single-output legacy systems.
