Method for treatment of coal ash, and method for desulfurization

Abstract

Provided are a method of treating coal ash by mixing it with water, in which the coal ash and water undergo a temperature difference therebetween while they are mixed; and a method of desulfurization in a coal combustion boiler system, which comprises mixing coal ash that has been separated from a ash collector in the system, with water on the condition that the two undergo a temperature difference therebetween while they are mixed, and circulating the resulting mixture that serves as a desulfurizing agent into the coal combustor in the system. The desulfurization capability of the desulfurizing agent used in the desulfurization method is higher than that of the desulfurizing agent obtained through hydration of coal ash with water or steam.

1 . A method of treating coal ash that contains a limestone-derived component, by mixing it with water, which comprises mixing the coal ash with water on a condition that the coal ash and water undergo a temperature difference therebetween while they are mixed.  
     
     
         2 . The method of treating coal ash as claimed in  claim 1 , wherein the temperature difference is at least 30° C.  
     
     
         3 . The method of treating coal ash as claimed in  claim 1  or  2 , wherein coal ash at a temperature falling between 80 and 150° C. is mixed with water at a temperature falling between 2 and 50° C.  
     
     
         4 . The method of treating- coal ash as claimed in  claim 1  or  2 , wherein coal ash at room temperature is mixed with hot water at a temperature falling between 60 and 98° C.  
     
     
         5 . The method of treating coal ash as claimed in any of  claims 1  to  4 , wherein 100 parts by weight of coal ash is mixed with from 20 to 200 parts by weight of water.  
     
     
         6 . The method of treating coal ash as claimed in any of  claims 1  to  5 , wherein the mixture of coal ash and water has a mean grain size of from 0.1 to 20 mm.  
     
     
         7 . A desulfurizing agent comprising the mixture of coal ash and water obtained in the treating method of any of  claims 1  to  6 .  
     
     
         8 . A soil improver comprising the mixture of coal ash and water obtained in the treating method of any of  claims 1  to  6 .  
     
     
         9 . A method of desulfurization in a coal combustion boiler system, which comprises mixing coal ash that has been separated from a ash collector in the system and contains a limestone-derived component, with water on the condition that the two undergo a temperature difference therebetween while they are mixed, and feeding the resulting mixture that serves as a desulfurizing agent into the coal combustor in the system.  
     
     
         10 . A method of desulfurization in a coal combustion boiler system, which comprises mixing coal ash that has been separated from a ash collector in the system and contains a limestone-derived component, with water on the condition that the coal ash at a temperature falling between 80 and 150° C. is mixed with water at a temperature falling between 2 and 50° C., and circulating the resulting mixture that serves as a desulfurizing agent into the coal combustor in the system.  
     
     
         11 . A method of desulfurization in a coal combustion boiler system, which comprises mixing coal ash that has been separated from a ash collector in the system and contains a limestone-derived component, with water on the condition that the coal ash at room temperature is mixed with hot water at a temperature falling between 60 and 80° C., and circulating the resulting mixture that serves as a desulfurizing agent into the coal combustor in the system.  
     
     
         12 . The desulfurization method as claimed in any of  claims 9  to  11 , wherein 100 parts by weight of coal ash is mixed with from 20 to 200 parts by weight of water.  
     
     
         13 . The desulfurization method as claimed in any of  claims 9  to  12 , wherein the mixture of coal ash and water having been so mixed that the temperature difference therebetween is at least 30° C. and having a mean grain size of from 0.1 to 20 mm serves as a desulfurizing agent.