Processing of waste incineration ashes

Abstract

The invention relates to a method for processing waste incineration ashes, in particular domestic waste incineration ashes, in which a process for classifying the ashes and a process for recovering phosphates from the ashes are combined. In said method, the ashes are subjected to a wet classification process during which the ashes are mixed with a liquid, and the ashes are treated with an acidic aqueous solution to redissolve the phosphates, whereupon the phosphates contained in the solution are isolated. The liquid with which the ashes are mixed during the wet classification process is the acidic aqueous solution with which the ashes are treated to redissolve the phosphates.

1 . A method for processing incinerator bottom ash (A) in which a method for classifying the ash (A) and a method for reclaiming phosphates (P) from the ash (A) are combined with one another,
 wherein the ash (A) is subjected to a wet classification and is in this respect mixed with a liquid (L);   wherein the ash (A) is treated with an acidic watery solution (L) for resolving the phosphates (P) and subsequently the phosphates (P) contained in the solution (L) are isolated; and   wherein the liquid with which the ash (A) is mixed within the framework of the wet classification is the acidic watery solution (L) with which the ash (A) is treated for resolving the phosphates (P).   
     
     
         2 . The method in accordance with  claim 1 , wherein
 a substantially closed liquid circuit is used for the wet classification of the ash (A), from which liquid circuit at least one portion of the acidic watery solution (L) is removed for the isolation of the phosphates.   
     
     
         3 . The method in accordance with  claim 1 , wherein
 the ash (A) is classified into at least one contaminated fine fraction (I) and into at least one low-contaminant or contaminant-free coarse fraction (II, III) in the wet classification while using classification processes gentle on the grain.   
     
     
         4 . The method in accordance with  claim 1 , wherein
 the ash (A) is only classified by wet classification;   and/or wherein the ash (A) is completely classified into at least one contaminated portion (I) and into at least one low-contaminant or contaminant-free portion (II, III).   
     
     
         5 . The method in accordance with  claim 1 , wherein
 the ash (A) is subjected to a mechanical pretreatment, in which metal parts and non-incinerated impurities are removed from the ash (A) prior to the wet classification;   and/or wherein the ash coming from the incinerator plant is pretreated such that the ash (A) is introduced into the wet classification with a grain size distribution whose upper limit does not amount to more than approximately 100 mm.   
     
     
         6 . The method in accordance with  claim 1 , the method comprising
 the following steps which are carried out after one another in time during the wet classification:
 the ash (A) is mixed with the acidic water solution (L); 
 at least one first coarse fraction (III) is separated from the product produced in this process; 
 at least one second coarse fraction (II) is separated from the product liberated of the first coarse fraction (III); 
 and 
 liquid (L) is removed from the fine fraction (I) produced in this process. 
   
     
     
         7 . The method in accordance with  claim 1 , wherein
 water (W) is provided for preparing the acidic watery solution (L) and an acid (S) is supplied to the water (W).   
     
     
         8 . The method in accordance with  claim 1 , wherein
 the isolation of the phosphates (P) is started in dependence on the pH of the acidic watery solution (L).   
     
     
         9 . The method in accordance with  claim 1 , wherein
 the phosphates (P) are isolated by reprecipitation.   
     
     
         10 . The method in accordance with  claim 1 , wherein
 the acidic watery solution (L) has a temperature in the range from 20 to 40° C.   
     
     
         11 . The method in accordance with  claim 1 , wherein
 the isolation of the phosphates (P) takes place in a device ( 27 ) which is separate from a device ( 21 ) for treating the ash (A) with the solution (L) and to which the solution (L) can be supplied in accordance with a removal which can be controlled or regulated.   
     
     
         12 . The method in accordance with  claim 1 , wherein
 the method is carried out in a processing plant ( 11 ) separate from the actual incinerator.   
     
     
         13 . The method in accordance with  claim 1 , wherein
 at least one parameter of a liquid used for the wet classification is held beneath or above a predefined limit value.   
     
     
         14 . A processing plant for incinerator bottom ash (A) which is configured for classifying the ash (A) and for reclaiming phosphates (P) from the ash (A),
 wherein the plant ( 11 ) comprises a treatment device ( 21 ) in which the ash (A) can be treated with an acidic watery solution (L) for resolving the phosphates (P) and an isolating device ( 27 ) in which the phosphates (P) contained in the solution (L) can be isolated;   wherein the plant ( 11 ) is configured for a wet classification of the ash (A) and in this respect is configured for a mixing of the ash (A) with a liquid (L); and   wherein the liquid with which the ash (A) can be mixed within the framework of the wet classification is the acidic watery solution (L) with which the ash (A) can be treated for resolving the phosphates (P).   
     
     
         15 . The processing plant in accordance with  claim 14 , in which
 the isolating device ( 27 ) is separate from the treatment device ( 21 ), with the solution (L) being able to be supplied to the isolation device ( 27 ) from the treatment device ( 21 ) by means of a removal device.   
     
     
         16 . The processing plant in accordance with  claim 14 ,
 further comprising at least one substantially closed liquid circuit for at least the wet classification.   
     
     
         17 . The processing plant in accordance with  claim 14 ,
 further comprising wet classification devices which are gentle on the grain and the plant being configured such that the ash (A) can be classified into at least one contaminated fine fraction (I) and at least one low-contaminant or contaminant-free coarse fraction (II, III).   
     
     
         18 . The processing plant ( 11 ) in accordance with  claim 14 ,
 the plant ( 11 ) being configured such that the lower limit of the grain size in the fine fraction (I) is 0 μm and the upper limit of the grain size approximately lies in the range from 50 to 500 μm.   
     
     
         19 . The processing plant ( 11 ) in accordance with  claim 14 ,
 further comprising a mixing stage ( 21 ) in which the ash (A) is mixed with the liquid (L), or vice versa.   
     
     
         20 . The apparatus in accordance with  claim 14 , the apparatus being configured to carry out a method for processing incinerator bottom ash (A).