High purity manganese and method for producing same
High purity manganese having a purity of 3N (99.9%) or more, wherein number of non-metal inclusions with a size of 0.5 μm or more is 50000 or less per 1 g of the high purity manganese. A method for producing high purity manganese, wherein refining is performed using a raw material (secondary raw material) obtained by acid-washing a manganese raw material (primary raw material) so that the produced high purity manganese has a purity of 3N (99.9%) or more, and number of non-metal inclusions with a size of 0.5 μm or more is 50000 or less per 1 g of the high purity manganese. The present invention provides a method for producing high purity metal manganese from commercially available manganese, and aims to obtain high purity metal manganese having a low LPC.
1. A method for producing a high purity manganese, comprising a refining process performed by the steps of:
acid-washing a manganese primary raw material having a purity of 2N or higher to remove contaminants and a layer of oxides from a surface thereof to obtain a secondary raw material;
leaching manganese with an acid from the secondary raw material to produce an acid leachate such that an amount of 1% or more of the secondary raw material remains undissolved within the acid leachate after said leaching step;
performing electrolysis using the acid leachate as an electrolytic solution on a cathode side of the electrolysis to obtain a manganese deposit; and
melting the manganese deposit in an inert atmosphere of a reduced pressure of 0.01 to 750 torr to eliminate impurities as slag and to obtain a cast ingot of high purity manganese having a purity of 3N (99.9%) or higher and containing a dispersion of foreign substances of non-metal inclusions with a size of 0.5 μm or larger in a number of 50000 or less per 1 g of the high purity manganese.
2. The method according to claim 1 , wherein, during said melting step, a deoxidizing agent having a stronger active potency than Mn is added to the manganese deposit and wherein the slag is concentrated on an upper part of the ingot.
3. The method according to claim 2 , wherein the deoxidizing agent is La, Ca or Mg.
4. The method according to claim 1 , further comprising the step of washing the manganese deposit with diluted nitric acid.
5. The method for producing high purity manganese according to claim 1 , wherein the amount of the secondary raw material remaining undissolved in the acid leachate is 1 to 50%.
6. The method according to claim 5 , wherein, during said melting step, a deoxidizing agent having a stronger active potency than Mn is added to the manganese deposit and wherein the slag is concentrated on an upper part of the ingot.
7. The method according to claim 6 , wherein the deoxidizing agent is La, Ca or Mg.
8. The method according to claim 6 , further comprising the step of washing the manganese deposit with diluted nitric acid.