Engineering Theory of Leaching

First, we normalize the tracer curve, so that the area under thecurve is 1. The area under the zinc curve is determined bygraphical integration (essentially, the trapezoidal rule). The areafor a particular time is the area between that time and the nexttime in the series.If the time intervals are large, this can bias the residence time tolower values, and yield a lower predicted oxidation. This happensbecause the each trapezoid is assigned to the lower time boundrather than the average of the upper and lower time bound. Abetter procedure in this case would be to plot the areas sodetermined at the mean of the respective time interval.32