Laboratory investigations of purification of trilonate solutions obtained during leaching of lead cakes of zinc production are carried out. Using the method of potentiometric titration, the conditions of formation of precipitates of lead sulfate and ethylenediaminetetraacetic acid are established. In this case, cations of impurity metals—zinc, copper, and iron—remain in the solution. The effect of the initial lead concentration in the solution and value of pH on the characteristics of purification are studied.