Abstract: In order to improve the automation level of the preparation system of mineral processing re⁃ agents in Dongbo concentrator，the general automatic dispensing system based on Siemens S7-1200 series PLC is studied in view of the high safety risk，low efficiency，large error and easy quality problems in the manual dispensing mode. The system works together through actuators (electric / pneumatic valves，agita⁃ tors)，sensors (electromagnetic flowmeters，radar level gauges) and control modules (AI/AO，DI/DO，serial server) to realize the functions of quantitative configuration of reagent，automatic dispensing，alarm of re⁃ agent shortage and alarm of ultra-high liquid level.The application results show that the system has been running stably for 2 years in Dongbo concentrator，and the number of single-shift dispensing workers has been reduced from 2 to 1. The abnormal process time caused by inaccurate dispensing is reduced by about 60 h each year，and the annual economic loss is about 10.125 million yuan. It effectively solves a series of problems caused by manual dispensing，and the system has good adaptability and versatility in different ap⁃ plication scenarios，which has certain application value.

Key words: fixed input of water quantity, constant reagent configuration concentration, automatic dis? pensing