High purity indium and manufacturing method therefor

Abstract

Provided is high purity Indium having a purity of 7N (99.99999%) or higher, and containing 0.05 ppm or less of Pb, 0.005 ppm or less of Zn, and 0.02 ppm or less of S. A method of producing high purity In, wherein SrCO 3 is added to an electrolyte upon performing electrolytic refining using 5N (99.999%) In to reduce Pb, Zn and S to attain a purity of 7N (99.99999%) or higher. Under circumstances where In demands for LED, such as InGaN and AlInGaP, are anticipated, it is necessary to produce indium in mass quantities and inexpensively, and the present invention provides technology capable of achieving the same.

1 : High purity In containing 0.05 ppm or less of Pb, 0.005 ppm or less of Zn, and 0.02 ppm or less of S, and having a purity of 7N (99.99999%) or higher. 
     
     
         2 : The high purity In according to  claim 1 , wherein the high purity In contains 0.001 ppm or less of Fe, less than 0.01 ppm of Sn, and less than 0.005 ppm of Si. 
     
     
         3 : A method of producing high purity In via electrolysis, wherein 5N (99.999%) In is used as a raw material, SrCO 3  is added to an electrolyte upon performing electrolytic refining using the raw material to reduce Pb content in the electrolyte, and electrodeposited In is separated from a negative plate and cast in an atmosphere or an oxygen-containing gas atmosphere to attain a purity of 7N (99.99999%) or higher. 
     
     
         4 : The method of producing high purity In according to  claim 3 , wherein an anode solution (anolyte) and a cathode solution (catholyte) are partitioned with a diaphragm having a gas permeability of 5 cm 3 /cm 2  sec or less, and the electrolyte in contact with a cathode is refined by being preliminarily filtered with a filter having fine pores of 0.5 μm or less. 
     
     
         5 : A method of producing high purity In via electrolytic refining, wherein electrolytic refining is performed by partitioning an anode solution (anolyte) and a cathode solution (catholyte) with a diaphragm having a gas permeability of 5 cm 3 /cm 2  sec or less, extracting a part of the catholyte into a catholyte tank that is different from an electrolytic bath and adding SrCO 3  to the catholyte in the catholyte tank to eliminate Pb in the catholyte, passing the catholyte with Pb eliminated therefrom through and filtering the catholyte with a filter having fine pores of 0.5 μm or less, and circulating and supplying the filtered catholyte so as to return the catholyte once again into a cathode box in the electrolytic bath. 
     
     
         6 : The method of producing high purity In according to  claim 5 , wherein sulfuric acid is used as the electrolyte, and electrolysis is performed at a pH of 0.5 to 1.5. 
     
     
         7 : The method of producing high purity In according to  claim 6 , wherein electrolysis is performed at a current density of 1 to 5 A/dm 2 . 
     
     
         8 : The method of producing high purity In according to  claim 7 , wherein electrolysis is performed under conditions in which an In concentration in the electrolyte is 65 to 120 g/L and a Cl concentration in the electrolyte is 6 to 10 g/L. 
     
     
         9 : The method of producing high purity In according to  claim 8 , wherein refining is performed upon adding 0.1 to 2.0 g/L of SrCO 3 . 
     
     
         10 : A method of producing high purity In, wherein high purity In produced with the electrolytic refining method of high purity In according to  claim 9  is separated from a negative plate and cast in an atmosphere or an oxygen-containing gas atmosphere at a temperature of 170 to 190° C. 
     
     
         11 : A method of producing high purity In produced with the electrolytic refining method of high purity In according to  claim 10  containing 0.05 ppm or less of Pb, 0.005 ppm or less of Zn, and 0.02 ppm or less of S, and having a purity of 7N (99.99999%) or higher. 
     
     
         12 : The method of producing high purity In according to  claim 3 , wherein sulfuric acid is used as the electrolyte, and electrolysis is performed at a pH of 0.5 to 1.5. 
     
     
         13 : The method of producing high purity In according to  claim 3 , wherein electrolysis is performed at a current density of 1 to 5 A/dm 2 . 
     
     
         14 : The method of producing high purity In according to  claim 3 , wherein electrolysis is performed under conditions in which an In concentration in the electrolyte is 65 to 120 g/L and a Cl concentration in the electrolyte is 6 to 10 g/L. 
     
     
         15 : The method of producing high purity In according to  claim 3 , wherein refining is performed upon adding 0.1 to 2.0 g/L of SrCO 3 . 
     
     
         16 : A method of producing high purity In, wherein high purity In produced with the electrolytic refining method of high purity In according to  claim 3  is separated from a negative plate and cast in an atmosphere or an oxygen-containing gas atmosphere at a temperature of 170 to 190° C. 
     
     
         17 : A method of producing high purity In produced with the electrolytic refining method of high purity In according to  claim 3 , wherein the high purity In contains 0.05 ppm or less of Pb, 0.005 ppm or less of Zn, and 0.02 ppm or less of S, and has a purity of 7N (99.99999%) or higher.