Manganese electrochemical manufacture

The current worldwide production capacity for manganese dioxide from electrochemical manufacture (EMD) is 194.5 10 t/a, that for chemical manufacture (CMD) 40 UT t/a. 34% of the worldwide EMD-production capacity is in Japan and 21% in the USA. The CMD-production capacities are much more strongly concentrated, 90% of the capacity being in the company Sedema in Belgium. 

The production of a ca. 97% pure manganese metal by reduction of low iron content manganese ores with silicon, which is not dealt with here, is industrially less important than its electrochemical manufacture. The estimated worldwide production capacity for the electrolytic manufacture of manganese in 1988 was 77 10 t/a. 

For the sake of comparison, similar cells have been made containing electrochemical manganese dioxide produced by Chiaturi plant, Georgia. Just this material is employed in practically all commercial lithium power sources manufactured in the countries of the former Soviet Union. 

The manufacture of secondary batteries based on aqueous electrolytes forms a major part of the world electrochemical industry. Of this sector, the lead-acid system (and in particular SLI power sources), as described in the last chapter, is by far the most important component, but secondary alkaline cells form a significant and distinct commercial market. They are more expensive, but are particularly suited for consumer products which have relatively low capacity requirements. They are also used where good low temperature characteristics, robustness and low maintenance are important, such as in aircraft applications. Until recently the secondary alkaline industry has been dominated by the cadmium-nickel oxide ( nickel-cadmium ) cell, but two new systems are making major inroads, and may eventually displace the cadmium-nickel oxide cell - at least in the sealed cell market. These are the so-called nickel-metal hydride cell and the rechargeable zinc-manganese dioxide cell. There are also a group of important but more specialized alkaline cell systems which are in use or are under further development for traction, submarine and other applications. 

The electrochemical processes for manufacturing manganese IV) oxide are currently the most important, industrially. Ca. 165 10 t of EMD was produced in 1986. A purified sulfuric acid manganese(II) sulfate solution is electrolyzed at 90 to 95°C on lead, titanium or graphite anodes at current densities of 0.5 to 1.2 A/dm-, whereupon mangane.se(II) is oxidized to manganese Ill) ... 

Batteries are known for about 100 electrochemical systems. Today, many of them are of mere historical interest. Commercially, batteries of less than two dozens of systems are currently produced. The largest production volumes are found in just three systems primary zinc-manganese batteries (today with an alkaline electrolyte, in the past with a salt electrolyte), rechargeable lead acid batteries, and rechargeable alkaline (nickel-cadmium, nickel-iron) batteries. Batteries of these systems have been manufactured for more than a century, and until today are widely used. 

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