Jacobs Journal of Civil Engineering

Distribution of Acid-Extractable Pb Contents in Molten Slag From Municipal Solid Waste Incineration Ash

Published on: 2016-03-28


In Japan, when molten slag from municipal solid waste incineration ash is used in the general environment, acid-extractable Pb contents must be lower than utilization criteria, as determined by JIS (Japanese Industrial Standard) K 0058-2 method. However, representativeness of 1,000 t of slag samples in practical usage is ineffective because only 6 g of samples are used for testing under such standards. This study has three aims: 1. to determine the variation of acid-extractable Pb contents in the 20 slag samples from one plant, 2. to estimate the probability of excess acid-extractable Pb content distributed among the 20 samples that adhere to utilization criteria, and 3. to show the importance of evaluating acid-extractable metal contents not based on a single analyzed value but probability density. In this study, twenty lots of slag were sampled from one melting plant for two months in 2006. In the first experiment, 6 g of samples were taken from each lot at random and tested. In the second experiment, 20 portions were prepared from four lots of them and 20 of 6 g samples were taken from each small portion and tested. The results indicate that significantly high Pb values derived from heterogeneous character. The dataset shows a log-normal distribution and the rates exceeding the utilization standard are discussed based on probability density function.


Molten Slag; Pb; Distribution; Acid-Extractable Content; Log-Normal Distribution