Manganese dioxide

 

Manganese dioxide

Chemical formula	MnO2
OTP appearance	brown/black solid
Molar Mass(g/mol)	86.9368
Density(g/cc)	5.026
Solubility in water(g/L)	insoluble
NFPA 704	0 1 0
Thermal Decomposition	Manganese dioxide 535°C Mn2O3

Uses

Primary

• Essential for several kinds of voltaic cells
• As an oxidizer for producing both potassium permanganate and chlorine
• Source of pure manganese via carbothermal reduction

Natural occurrence

• Manganese dioxide occurs naturally as pyrolusite

Production

Extraction

from pyrolusite

Manganese dioxide is purified from the raw material (pyrolusite) by dissolving the pyrolusite in a solution of sulfuric acid, sometimes adulterated with manganese sulfate. A current is applied, and the purified manganese dioxide is deposited on the anode.

from psilomelane

Manganese dioxide is produced (along with chlorine gas and some barium chloride) by the processing of psilomelane:

1. Crush psilomelane to a fine powder
2. Dissolve in dilute (but proportional) hydrochloric acid, producing some chlorine gas.

   MnO₂ + 4 HCl → MnCl₂ + 2 H₂O + Cl₂

3. Filter
4. Discard residue
5. Precipitate the iron chloride by converting it to prussian blue
6. Filter
7. Retain residue of prussian blue
8. Evaporate filtrate
9. Roast residue, producing manganese dioxide and chlorine gas, leaving the other (sodium, potassium, barium) chlorides unchanged.
10. Wash with water
11. Filter
12. Residue is manganese dioxide
13. Filtrate contains assorted chlorides.

See Also

• US patent 2262185 "Process of extracting manganese from lean ores."
  Link courtesy Google