Tj. Cardwell et al., DETERMINATION OF SULFURIC-ACID IN METALLURGICAL PROCESS STREAMS BY DISCONTINUOUS FLOW-ANALYSIS, Analytica chimica acta, 308(1-3), 1995, pp. 197-205
Discontinuous flow analysis was applied to the determination of sulfur
ic acid in metallurgical process samples by photometric titration usin
g a bromophenol blue indicator. Over-estimation of the level of acid d
ue to the precipitation of metal hydroxides and oxides was prevented b
y titrating with sodium acetate. At a throughput of 110 samples h(-1),
the method exhibited excellent repeatability and reproducibility, wit
h relative standard deviations of less than 1% throughout. Determinati
ons on samples taken from copper, manganese and zinc refining operatio
ns compared well with results obtained using the existing industry pro
cedure of manual titration with hydroxide to a pH 3.9 endpoint. Of twe
lve metals investigated, only arsenic(V) and iron(III) interfered to a
significant extent. High levels of cadmium, chromium(III), copper(II)
and lead(II) resulted in small positive errors, whereas calcium, coba
lt(II), magnesium, manganese(II), nickel(II) and zinc did not interfer
e.