Open cast tin mining was mainly of Chinese (miners) operation. A thunderous water jet would wash the hill slope, the soil mix is pumped up the sluice for tin separation.
I met Leong Sin Nam's son at his thoracic clinic, Ipoh. The Garden Hotel, Tanah Rata (has changed hands and under new name) was built by his father where I used to loaf with friends decades ago.
The last remaining dredge supposedly for tourist attraction near Batu Gajah is poorly maintained. Tronoh, (where we domicile) lies in the Kinta Valley which was also in the hub of the tin glory days then.