Weldon process

The Weldon process is a process developed in 1870 by Walter Weldon for recovering manganese dioxide for re-use in chlorine manufacture.

Additional recommended knowledge

Daily Visual Balance Check

How to quickly check pipettes?

Essential Laboratory Skills Guide

After reacting hydrochloric acid with manganese dioxide (and related oxides), the waste manganese(II) chloride solution is treated with lime, steam and oxygen, producing calcium manganite (IV):

2MnCl₂ + 3Ca(OH)₂ + O₂ → CaO·2MnO₂ + 3H₂O + 2CaCl₂

The resulting calcium manganite can be reacted with HCl as in related processes:

CaO·2MnO₂ + 10HCl → CaCl₂ + 2MnCl₂ + 2Cl₂ + 5H₂O

The MnCl₂ can be recycled, while the CaCl₂ is a waste byproduct.