Uses of manganese
The main users of manganese are, or have been:
- the chlorine industry for bleach manufacture
- the steel industry
- other metallurgical applications
- other uses in the chemical industry
The industrialisation of the cotton industry
Uses of manganese
The main users of manganese are, or have been:
- the chlorine industry for bleach manufacture
- the steel industry
- other metallurgical applications
- other uses in the chemical industry
The industrialisation of the cotton industry in the late eighteenth and early nineteeth centuries required an industrial-scale method of bleaching cotton. The use of ‘bleaching powder’ (chloride of lime and other chlorine/calcium compounds) reduced the time taken to bleach cotton from months (bleaching in sunlight, later superceded by bleaching using suphuric acid) to hours. The manufacture of paper and soap also required bleach.
Commencing in the 1780s, chlorine for bleach manufacture was obtained from salt by reaction with sulphuric acid and manganese dioxide. This method declined towards the end of the 19th century in response to the introduction of chlorine production processes from the hydrochloric acid by-product of the Leblanc process (manufacture of sodium carbonate).
One of these chlorine production processes, the Weldon process, involved boiling hydrochloric acid with the manganese to produce chlorine and manganese chloride. (The remains of Weldon chlorine stills can be seen at Spike Island, Widnes.) Manganese was considered to be expensive by the chlorine industry and recovery processes for its reuse were developed [Twigg 2001]. One such recovery process involved treating the manganese chloride with milk of lime (a thin cream of slaked lime and water) to make ‘Weldon Mud’ or ‘Recovered Manganese’ (a mixture of calcium manganite CaO.2MnO2 and manganese manganite MnO.MnO2). This was separated from the calcium chloride solution and used again in the chlorine production process. [Gardner & Cooke 1971: 669]
Welsh manganese ores, in the oxide form, were used for these purposes in the chemical works around Glasgow associated with the cotton industry in the 19th century.
The steel industry
In Ancient Greece, the presence of manganese in the iron ore used by the Spartans is a possible explanation as to why their steel weapons were superior to those of their enemies. The same is also said of steel from Toledo, Spain [Chambers No. 659, 1876: 543–44]. At the beginning of the 19th century, both British and French scientists began considering the use of manganese in steelmaking, with patents granted in the U.K. in 1799 and 1808. In Germany in 1816 it was reported that manganese increased the hardness of iron, without reducing its malleability or toughness and in 1826 Prieger produced a ferromanganese containing 80% manganese. J.M. Heath produced metallic manganese in England in about 1840. The following year, Pourcel began industrial-scale production of "spiegeleisen", a pig-iron containing a high percentage of manganese, and in 1875 he started the commercial production of ferromanganese with a 65% manganese content. [IMnI] From 1848, Robert Mushet (1811–1891) experimented with spiegeleisn at the Darkhill Iron Works in the Forest of Dean. In 1856 he patented the Bessemer-Mushet process and produced the first steel for rail in 1857 [Thomas 1999]. In 1860 Bessemer used this work to develop his own steel-making process. In 1866, Siemens patented the use of ferro-manganese in steelmaking so as to control the levels of phosphorus and sulphur. In 1883 Robert Hadfield found that manganese steel (containing 13% manganese) combined great toughness and hardness [Fermor 1945: 41].
From the mid 19th century the use of manganese to improve the wear resistance and hardness of steel quickly became (and remains) by far its largest single use. At least 90% of world manganese ore production is used by the iron and steel industries [Dewey & Dines 1923: 49]. In the 1940s an average 14lb (6kg) of manganese was nee