Because it did not come from China. It is the residue from a Chinese owned factory in Tak. My understanding is that approved disposal of the slag consists of mixing it with cement or concrete in a 'pond' presumably as landfill. Some was but has now been dug up, bagged, and shipped to the southern warehouse. Other slag was bagged and shipped direct. This would appear to be because the commodity value of Cadmium in demand for EV battery manufacture has risen and the unwanted slag now has considerable value. Ironically, I suspect the intention was to ship it to China at some point. 😀