Phosphorus is produced in an electric furnace. The electrical resistance of the furnace burden and the arc between the electrodes convert electrical energy into heat, heating the burden to 1,500-1,600°C until it melts. Reduction reactions produce phosphorus vapor, carbon monoxide, phosphine, hydrogen sulfide, silicon tetrafluoride, slag, ferrophosphorus, and other products. This production activity includes: 1) raw-material preparation; 2) phosphorus production and collection; 3) phosphorus-sludge recovery; 4) yellow-phosphorus off-gas purification and utilization; 5) flue-gas scrubbing; and 6) visible-plume removal.