METHOD FOR MEASURING COMPONENTIAL CONCENTRATION OF SULFURIC ACID-HYDROFLUORIC ACID SERIES STEEL PICKLING SOLUTION

摘要

PROBLEM TO BE SOLVED: To attain the speed-up and automation of measuring the electric conductivity of a pickling solution by finding the concentration of free sulfuric acid from a calibration curve, measuring the electric conductivity of a solution obtained by adding Fe (NO3)3 or FeCl3 to the pickling solution and finding the concentration of free hydrofluoric acid from a calibration curve. ;SOLUTION: The electric conductivity of a pickling solution has been measured, and a calibration cure (a) of the electric conductivity-the concentration of sulfuric acid has been prepared. The electric conductivity L1 of the pickling solution is measured, the concentration of sulfuric acid S1 equivalent to L1 is read out from the calibration curve (a), and this is defined as the concentration of free sulfuric acid in the pickling solution. Then, the electric conductivity of a solution obtained by adding Fe (NO3)3 or FeCl3 of the molar number equal to or above that or HF has previously been measured, and a calibration curve (c) of the electric conductivity-the total concentration of acid has been prepared. The electric conductivity L2 of a solution obtained by adding Fe (NO3)3 or FeCl3 to the picking solution similarly to the above is measured, the total concentration of acid S2 equivalent to L2 in the calibration curve (c) is found, and S2-S1=ΔS is defined as the concentration of free hydrofluoric acid.;COPYRIGHT: (C)2001,JPO