In the alumina production system, the qualified raw ore pulp is pumped to the high-pressure dissolver through the diaphragm, the 55KW diaphragm pump is driven by a D32 75KW inverter, and the 4-20mA feedback signal output by the slurry electromagnetic flowmeter is sent to the inverter. The closed-loop control is realized on the feedback port of the PI regulator, so that the flow rate of the slurry can be changed within a given range to ensure the highest dissolution rate of alumina.