World production of electrolytic manganese metal based method, to obtain a high-grade metal manganese w (Mn)> 99.7% of the method, manganese ore types and grades can be used more widely, the raw material can be manganese carbonate, manganese dioxide, and Manganese-rich slag smelted in blast furnace.
Electrolytic production of manganese metal, although the standard electrode potential of manganese is -1.18V, but due to the overvoltage of hydrogen on the metal manganese, manganese can still be precipitated from the neutral solution to the cathode, but the current efficiency is low, generally 65% ~75%.
An important condition for electrolysis is that the manganese sulfate solution is required to be free of other metals as much as possible, so the manganese sulfate solution must be sufficiently purified before electrolysis, and a diaphragm electrolysis cell is used.
The industrial production process for the electrolysis of manganese sulfate solution is shown in the figure below.
The manganese manganese sulfate solution is used as a raw material to prepare electrolytic manganese metal. The raw materials required are: manganese ore powder, sulfuric acid, ammonium sulfate, liquid ammonia, oxidant, reducing agent, and additives.
1. Manganese ore powder, two types of manganese ore and pyrolusite.
(1) rhodochrosite (MnCO 3 ), the quality requirements are in line with the national standard GB3714-83 level 1-4.
(2) Pyrolusite (MnO 2 ), the quality requirements are in line with the national standard GB3713-83 level 1-4.
From the production point of view, it is desirable that the manganese content is high, the types of impurity elements are small and the content is low, and in particular, the content of iron and heavy metal elements is required to be as low as possible.
2. Industrial sulfuric acid (H 2 SO 4 ) quality indicators should comply with national standards GB534-65.
3. The quality index of ammonium sulfate [(NH 4 ) 2 SO 4 ] should conform to the national standard GB535-65.
4. The quality index of liquid ammonia or ammonia water (NH 3 , NH 3 • H 2 O) should meet the national standard GB536-65 or the Ministry of Chemical Industry standard HCI-88-64 (CO 2 content is not more than 0.05g / L).
The reducing agent (1) anthracite powder, particle size 2mm or less, ash content of 8% to 13%.
(2) Pyrite FeS 2 , S content of 35% ~ 40%.
6. Scavenger (except heavy metals)
(1) Saturated (NH 4 ) 2 S solution (hydrogen sulfide is produced by reacting sulfuric acid with sodium sulfide, and then absorbed into saturated yellow oily liquid with ammonia water).
(2) Fumei sodium [sodium dimethylaminosulfonate (CH 3 ) 2 NCS 2 Na] is abbreviated as SDD, and the content is 88% or more.
(3) Ethyl sulfide (sodium diethyldithiocarbamate trihydrate) [(CH 3 CH 2 ) 2 NCS 2 Na•3H 2 O].
7. Additives (1) Sulfur dioxide (SO 2 ), the quality is in line with Hunan Q/HG67-80.
(2) Selenium dioxide (SeO 2 ), the content is 98% to 99%.
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