Exchange pH value: take 20.00g of screened ore sample below 20 mesh and 2wt% ammonium sulfate mixed according to mass ratio 1:4, put it in 250ml beaker, put it on multi-head magnetic stirrer and stirred, set the speed to 1000 r/s, stirred for 30 min, then filtered, take the clarified filtrate, measure its pH value is the exchange pH value with 2wt% ammonium sulfate. The exchange pH of different mineral samples and different components of the same mineral sample with different types and concentrations of leaching agents are different.