Carbon throughput: | Tonnes per day of spent carbon to be treated. This sets the kiln size, drum length/diameter or vertical kiln dimensions. |
Temperature and atmosphere: | The kiln must achieve sufficient temperature to remove foulants without damaging the carbon structure. Steam or inert atmospheres are frequently used to control oxidation. |
Residence time: | The duration the carbon remains within the high-temperature zone is critical to allow desorption of contaminants. Design must allow sufficient time for regeneration. |
Carbon attrition and physical degradation: | The regeneration process can cause carbon particle degradation (fines generation) which leads to loss of carbon and possibly gold loss. Kiln design should minimise mechanical stress and attrition. |
Heat recovery and energy efficiency: | Because high temperatures are involved, design often includes heat-recovery (e.g., recycle ducts, steam generation) to reduce fuel/energy consumption. |
Emission control and environmental compliance: | Volatilised contaminants and gaseous emissions must be treated via after-burners or scrubbers. The kiln atmosphere and discharge must meet emissions standards. |
Material construction and wear: | The kiln components (drum, liners, seals) must tolerate high temperatures, corrosive/abrading carbon, steam, and inert gas cycling. Design must allow access for maintenance and pre-empt wear. |
Operating | ~650-850 °C | Depends on foulant load and carbon type. |
Carbon | ~0.5 to ~20 t/day (or higher for custom units) | |
Carbon | ~5-10% per regeneration cycle | |
Steam injection | Required to avoid carbon combustion | |
Heat | Often included to reduce fuel consumption | Energy-efficiency measure. |