Manganese metal production
According to metal powder supplier, manganese metal production has aluminum thermal, silicon thermal methods and electrolysis methods three kinds.
Aluminum thermal method must use high-quality manganese ore as raw material, and the aluminum consumption is large, high cost; the silicon thermal power has a long process, the operation is relatively complex; the electrolysis method widely used because of it can use poor manganese ore as raw materials to obtain high purity manganese metal products.
Aluminum thermal method, in magnesia lining-up vertical furnace, use aluminum as reducing agent, the process of reducing manganese oxides (Mn2O3 or Mn3O4) output of manganese metal. In order to get qualified products, aluminum thermal method generally used low impurity manganese oxide minerals as raw materials. The pulverized manganese oxide is about 90% of the theoretical requirement of the aluminum particles and the equivalent amount of aluminum 10% to 20% of the lime mixed evenly, manganese metal ignition reduction to obtain manganese metal contains more than 90% manganese.
The silicon thermal methods, while treating non-quality manganese ore, generally use a three-step reduction. The first step, add a small amount of manganese ore with coke in an electric furnace to restore, get low iron and low phosphorus manganese-rich slag. The second step, use charcoal reduce manganese-rich slag, refining low phosphorus carbon ferromanganese; low phosphorus carbon ferromanganese plus silica, charcoal refining high silicon-manganese alloy. The third step, use high silicon manganese alloy and manganese-rich slag with lime, to desilication refined in an electric arc furnace, get a purity of 93% to 97% manganese metal.
The electrolytic method, the electrolytic manganese metal is the production of manganese powder, the raw material can be manganese oxide or manganese carbonate. If use the manganese oxide minerals as raw materials, adding reduce agent directly leaching, also can be through reducing roast and then leaching. The process of using manganese carbonate as raw material is composed of leaching, oxidation, purification and electrowinning and other operations.
Leaching, used the anolyte returned to sulfuric acid and electrolytic deposition process as the solvent, in acid leaching tank added slurried the manganese carbonate powder. Under the conditions of acid mine 0.5 to 0.55, 363K leaching temperature, leaching 4 ~ 8h, control leaching endpoint, pH1.0 to 1.5, then the manganese of MnCO3 will generate water-soluble MnSO4 into the solution.
The oxidation, the purpose is to remove the iron, aluminum and other impurities in leaching solution. Often use manganese dioxide powder as the oxidant, oxidized the divalent iron in the leach solution into trivalent iron, use liquid ammonia or lime as the neutralizing agent, adjusted the solution to pH 7.0 ~~ 7.2, so that impurities such as iron, aluminum hydrolysis removed by precipitation.
Purification, the qualified lixivium after coarse filtration, the filtrate was sent for purification. Cleaning operation carried out in the purge vessel, added the purification agent in tank to remove. The purified solution by the fine filter, is the new agent Diethyldithiocarbamate (of diethyl sulfonitriding ammonium sodium formate) or sulfide liquid heavy metal precipitation required by electrolytic deposition.
Electrolytic deposition, there are certain requirements on the quality of the new liquid heteroaryl. Manganese electrowinning use diaphragm electrolysis. Electrolytic cell with a diaphragm divide into an anode chamber and a cathode chamber, the anode is generally use silver, tin, antimony, lead alloy sheet, the net area of the anode conductive is 60% to 65% of cathode conductive area, the current density is 40% to 35% higher than the cathode. The cathode generally used titanium, cathode current density is 450 to 500A/m. The cell voltage is about 5V. The electrolytic deposition new liquid by the high slot sent to the cathode chamber, the anolyte containing MnO2 discharged from the bottom of the groove. When the manganese metal deposited a thickness of 1.5 ~ 2mm on the cathode (Usually electrolytic 24h), remove the cathode plate, and placed in a new cathode plate to continue electrolysis. The removed cathode was through cleaning, drying, peeling from the metal manganese. The peeled manganese metal by equipped is electrolytic manganese product.
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