Method for stabilization of reducing slag

Abstract

A method for stabilizing a reducing slag includes the steps of: subjecting a reducing slag which contains an alkaline earth metal oxide to a drying treatment, so as to obtain a dried reducing slag; mixing a urease-producing bacterium, a fermentation medium, and a nutrient, followed by conducting a fermentation treatment, so as to obtain a fermentation product containing urease; subjecting the fermentation product to a foam fractionation treatment, so as to obtain a foam containing urease; mixing the dried reducing slag, the foam containing urease, and urea, followed by conducting a urea hydrolysis reaction and a precipitation reaction in sequence, so as to obtain a product containing a stabilized reducing slag and a residual liquid; and subjecting the product to a solid-liquid separation treatment, so as to separate the stabilized reducing slag and the residual liquid from the product.

What is claimed is: 
     
         1 . A method for stabilizing a reducing slag, comprising the steps of:
 (a) subjecting a reducing slag which contains an alkaline earth metal oxide to a drying treatment, so as to obtain a dried reducing slag, the alkaline earth metal oxide being selected from the group consisting of calcium oxide, magnesium oxide, and a combination thereof;   (b) mixing a urease-producing bacterium, a fermentation medium, and a nutrient, followed by conducting a fermentation treatment, so as to obtain a fermentation product containing urease;   (c) subjecting the fermentation product containing urease obtained in step (b) to a foam fractionation treatment, so as to obtain a foam containing urease, a concentration of the urease in the foam being greater than a concentration of the urease in the fermentation product;   (d) mixing the dried reducing slag obtained in step (a), the foam containing urease obtained in step (c), and urea, followed by conducting a urea hydrolysis reaction and a precipitation reaction in sequence, so as to obtain a product containing a stabilized reducing slag and a residual liquid; and   (e) subjecting the product obtained in step (d) to a solid-liquid separation treatment, so as to separate the stabilized reducing slag and the residual liquid from the product.   
     
     
         2 . The method as claimed in  claim 1 , wherein in step (b), the urease-producing bacterium is an aerobic bacterium selected from the group consisting of  Sporosarcina pasteurii, Bacillus subtilis , and a combination thereof. 
     
     
         3 . The method as claimed in  claim 1 , wherein in step (b), the urease-producing bacterium is an anaerobic bacterium selected from the group consisting of  Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus fermentum , and combinations thereof. 
     
     
         4 . The method as claimed in  claim 1 , wherein in step (c), the foam fractionation treatment is conducted by introducing a gas into the fermentation product containing urease, so as to generate the foam containing urease. 
     
     
         5 . The method as claimed in  claim 4 , wherein the gas is air. 
     
     
         6 . The method as claimed in  claim 1 , wherein in step (a), the reducing slag is subjected to a sterilization treatment before or simultaneously with the drying treatment, the sterilization treatment being conducted using ultraviolet light. 
     
     
         7 . The method as claimed in  claim 1 , wherein in step (a), the dried reducing slag is further subjected to a sterilization treatment after the drying treatment, the sterilization treatment being conducted using ultraviolet light. 
     
     
         8 . The method as claimed in  claim 1 , wherein in step (a), the drying treatment is conducted using sunlight. 
     
     
         9 . The method as claimed in  claim 1 , wherein in step (b), the fermentation treatment is conducted at a temperature ranging from 15° C. to 40° C. for a time period ranging from 16 hours to 120 hours. 
     
     
         10 . The method as claimed in  claim 1 , wherein in step (c), the foam fractionation treatment is conducted at a temperature ranging from 15° C. to 40° C. 
     
     
         11 . The method as claimed in  claim 1 , wherein in step (d), the urea hydrolysis reaction and the precipitation reaction are conducted at a temperature ranging from 15° C. to 40° C.