Geochemistry of a spheroidal weathering profile in a tropical mountainous landscape, Rio de Janeiro, Brazil.

Boulders are an important material in debris flow and their source is coupled with spheroidal weathering profiles that produce corestones. The goal of this work was to establish the geochemical transformations that produced corestones and distinguished them from the surrounding grus in two tropical granite weathering profiles (P1 and P2). Sampling was not performed in a vertical profile; instead, we gathered 13 (P1) to 16 (P2) samples displaying different weathering degrees (corestone and saprolite) and spatial positions in the profiles.

Recovery of base metals, silicon and fluoride ions from mobile phone printed circuit boards after leaching with hydrogen fluoride and hydrogen peroxide mixtures.

The recovery of copper, nickel, zinc, silicon, iron, aluminum, tin and fluoride ions from fluoride leach liquors of non-ground printed circuit boards (PCBs) from mobile phones is described in detail. These PCBs were leached with HF + HO mixtures after previous treatment with 6 mol L NaOH (removal of the solder mask). A combination of solvent extraction (SX) and precipitation techniques was used.