Method and apparatus for recovering indium from waste liquid crystal displays

Abstract

This invention provides a method and apparatus for recovering In in the form of an alloy or a metal simple substance as a valuable material from waste LCD. In the In recovery method and apparatus, there is no need to recover In as indium hydroxide, and In can be recovered as a valuable metal. Accordingly, unlike the case of indium hydroxide, the recovery does not suffer from poor handling, and In can easily be recovered through a filter or the like with significantly improved In recovery. The In recovery method is characterized by comprising crushing waste LCD containing indium tin oxide, dissolving indium tin oxide from the crushed waste LCD with an acid to give an indium compound-containing solution, allowing the solution to flow into a reactor for recovery and, further, adding particles of a metal having a larger ionization tendency than In into the reactor for recovery, fluidizing the metal particles, precipitating In or an In alloy contained in the indium compound-containing solution onto the surface of the metal particles, then separating the precipitated In or In alloy from the metal particles by separation means, and separating and recovering the separated solid In or In alloy from the liquid component.

1 . A method of recovering indium from waste liquid crystal displays, comprising:
 crushing waste liquid crystal displays that contain indium tin oxide; dissolving the indium tin oxide from the waste liquid crystal displays by using acid, thereby producing an indium composition containing solution; flowing the same into a recovering reactor while adding metal particles of a metal having an ionization tendency larger than indium into the recovering reactor; fluidizing the   metal particles; precipitating indium or indium alloy contained in the indium composition containing solution onto the surface of the metal particles; then separating the deposited indium or indium alloy from the metal particles by a separating means; and isolating and recovering the separated indium or indium alloy in a solidified form from the liquid component.   
   
   
       2 . A method of recovering indium from waste liquid crystal displays according to  claim 1 , wherein the metal particles of the metal having an ionization tendency larger than indium are any one of zinc particles and aluminium particles. 
   
   
       3 . A method of recovering indium from waste liquid crystal displays according to  claim 1 , wherein the separating means for separating the indium or indium alloy deposited onto the metal particles comprises any one of a vibrating means for vibrating the metal particles by ultrasonic waves and a stirring means for stirring the metal particles by electromagnet and thereby making the metal particles collide with one another. 
   
   
       4 . A method of recovering indium from waste liquid crystal displays according to  claim 1 , wherein the indium composition-containing solution produced by dissolving the indium tin oxide from the waste liquid crystal displays is flown into an impurity removing reactor prior to the flowing of the indium composition-containing solution into the recovering reactor; metal particles of a metal having an ionization tendency larger than an impurity metal other than the indium in the indium composition-containing solution are added into the impurity removing reactor, thereby fluidizing the metal particles and depositing the impurity metal on the surface of the metal particles; and then the deposited impurity metal is separated and removed from the metal particles by the separating means. 
   
   
       5 . A method of recovering indium from waste liquid crystal displays according to  claim 4 , wherein the separating means for separating the impurity metal deposited onto the metal particles comprises any one of a vibrating means for vibrating the metal particles by ultrasonic waves and a stirring means for stirring the metal particles by electromagnet and thereby making the metal particles collide with one another. 
   
   
       6 . A method of recovering indium from waste liquid crystal displays according to  claim 4 , wherein the impurity metal is tin. 
   
   
       7 . A method of recovering indium from waste liquid crystal displays according to  claim 4 , wherein the metal particles of the metal having an ionization tendency larger than the impurity metal are iron particles. 
   
   
       8 . A method of recovering indium from waste liquid crystal displays according to  claim 7 , wherein alkali is added into the indium composition-containing solution with the impurity metal removed therefrom, and iron is removed in the form of hydroxide by sedimentation. 
   
   
       9 . A method of recovering indium from waste liquid crystal displays, comprising:
 crushing waste liquid crystal liquid displays that contain indium tin oxide; dissolving the indium tin oxide from the waste liquid crystal displays by using acid, while the crushed waste liquid crystal displays are kept placed in a bag, thereby producing an indium composition-containing solution; and washing and neutralizing the waste liquid crystal displays placed in the-bag and then drying the same.   
   
   
       10 . An apparatus for recovering indium from waste liquid crystal displays, comprising:
 a crusher for crushing waste liquid crystal liquid displays that contain indium tin oxide; an indium dissolution device for dissolving the indium tin oxide from the waste liquid crystal displays by using acid, thereby producing an indium composition-containing solution; a recovering reactor for allowing the indium composition-containing solution produced by the indium dissolution device to flow into the recovering reactor while allowing metal particles of a metal having an ionization tendency larger than indium to be added into the recovering reactor, thereby carrying out a metal deposition reaction that deposits indium or indium alloy onto the metal particles; a separating means for separating the deposited indium or indium alloy from the metal particles to recover the same; and an isolating means for isolating the separated indium or indium alloy in a solidified form from the liquid component.   
   
   
       11 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 10 , wherein the metal particles of the metal having an ionization tendency larger than indium are any one of zinc particles and aluminium particles. 
   
   
       12 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 10 , wherein the separating means for separating the indium or indium alloy deposited onto the metal particles comprises any one of a vibrating means for vibrating the metal particles by ultrasonic waves and a stirring means for stirring the metal particles by electromagnet and thereby making the metal particles collide with one another. 
   
   
       13 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 10 , wherein an impurity removing reactor is disposed on the upstream side of the recovering reactor, said impurity removing reactor being arranged to flow the indium composition-containing solution produced by the indium dissolution device into the impurity removing reactor; add metal particles of a metal having an ionization tendency larger than an impurity metal other than the indium in the indium composition-containing solution into the impurity removing reactor, thereby fluidizing the metal particles and depositing the impurity metal onto the surface of the metal particles; and have a means of separating and removing the deposited impurity metal from the metal particles. 
   
   
       14 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 13 , wherein the separating means for separating the impurity metal deposited onto the metal particles comprises any one of a vibrating means for vibrating the metal particles by ultrasonic waves and a stirring means for stirring the metal particles by electromagnet, thereby making the metal particles collide with one another. 
   
   
       15 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 13 , wherein the impurity metal is tin. 
   
   
       16 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 13 , wherein the metal particles of the metal having an ionization tendency larger than the impurity metal are iron particles. 
   
   
       17 . An apparatus for recovering indium from waste liquid crystal displays according to  claim 16 , wherein alkali is added into the indium composition-containing solution with the impurity metal removed therefrom, and iron is removed in the form of hydroxide by sedimentation.