Method for eluting calcium from steel slag and method for recovering calcium from steel slag

Abstract

The purpose of the present invention is to provide a method for eluting calcium from steel slag such that more calcium can be eluted into an aqueous solution containing carbon dioxide from the steel slag. The present invention comprises carrying out, in the following order, a step of subjecting a calcium compound contained in the steel slag to hydration and a step of bringing the steel slag subjected to the hydration into contact with the aqueous solution containing carbon dioxide. Furthermore, in the present invention, the aqueous solution containing carbon dioxide is brought into contact with the steel slag while the steel slag is being pulverized or the surface of the steel slag is being ground. As a result of these methods, more calcium can be easily eluted into the aqueous solution containing carbon dioxide from the steel slag.

1 . A method for eluting calcium from steelmaking slag, the method comprising:
 subjecting the steelmaking slag to hydration treatment;   wherein, in the hydration treatment, the steelmaking slag is immersed in water containing 300 mg/l of carbon dioxide or less and left to stand, or water and the steelmaking slag are mixed and kneaded into a paste, followed by leaving the paste to stand; and   bringing the steelmaking slag that has been subjected to the hydration treatment into contact with an aqueous solution containing carbon dioxide.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . (canceled) 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . The method according to  claim 1 , wherein, in the bringing the steelmaking slag into contact with the aqueous solution containing carbon dioxide, the steelmaking slag in contact with the aqueous solution containing carbon dioxide is fractured or pulverized, or a surface of the steelmaking slag in contact with the aqueous solution containing carbon dioxide is ground. 
     
     
         8 . A method for eluting calcium from steelmaking slag, the method comprising:
 bringing the steelmaking slag into contact with an aqueous solution containing carbon dioxide, and   during the bringing of the steelmaking slag into contact with the aqueous solution, pulverizing the steelmaking slag using a crusher, or grounding a surface of the steelmaking slag using the crusher.   
     
     
         9 . The method according to  claim 8 , wherein the steelmaking slag has been subjected to hydration treatment. 
     
     
         10 . A method for recovering calcium from steelmaking slag, the method comprising:
 eluting the calcium from the steelmaking slag by the method according to  claim 1 ; and   recovering the eluted calcium.