The Weldon process is a process developed in 1866 by

Walter Weldon Walter Weldon FRS FRSE (31 October 183220 September 1885) was a 19th-century English industrial chemist and journalist. He was President of the Society of Chemical Industry 1883/84. Life He was born in Loughborough on 31 October 1832, the son ...

for recovering manganese dioxide for re-use in

chlorine Chlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine i ...

manufacture. Commercial operations started at the Gamble works in St. Helens in 1869. The process is described in considerable detail in the book, The Alkali Industry, by J.R. Partington,D.Sc. The common method to manufacture chlorine at the time, was to react manganese dioxide (and related oxides) with hydrochloric acid to give chlorine: : MnO₂ + 4 HCl → MnCl₂ + Cl₂ + 2H₂O Weldon's contribution was to develop a process to recycle the manganese. The waste manganese(II) chloride solution is treated with lime, steam and oxygen, producing calcium manganite(IV): : 2 MnCl₂ + 3 Ca(OH)₂ + O₂ → CaO·2MnO₂ + 3 H₂O + 2 CaCl₂ The resulting calcium manganite can be reacted with HCl as in related processes: : CaO·2MnO₂ + 10 HCl → CaCl₂ + 2 MnCl₂ + 2 Cl₂ + 5 H₂O The manganese(II) chloride can be recycled, while the calcium chloride is a waste byproduct. The Weldon process was first replaced by the Deacon process and later by the

Chloralkali process The chloralkali process (also chlor-alkali and chlor alkali) is an industrial process for the electrolysis of sodium chloride (NaCl) solutions. It is the technology used to produce chlorine and sodium hydroxide (caustic soda), which are commodit ...

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Further reading