Method and system for fine particulate removal and processing from a coal combustion residual surface impoundment
A method and system for removing a slurry from a surface impoundment to create a dewatered particulate cake on a filter bed is disclosed.
1 . A in situ process for remediating a coal ash pond to produce a coal combustion residual material-based cake bed, the process comprising the steps of:
a. Extracting an ash slurry from a coal ash retention pond;
b. Scalping the ash slurry to separate coarse ash components and fine ash components;
c. Placing the fine ash components in a thickener to create a thickened underflow and an overflow, the overflow being returned to the coal ash retention pond; and
d. Depositing the thickened underflow upon a mechanical dewatering device including a vacuum belt filter, or belt filter press, or plate filter press to create a filtrate and a cake bed, the filtrate being returned to the thickener and the coal ash retention pond, the cake bed consisting of fine components for subsequent transport away from the coal ash pond.
2 . The process of claim 1 , wherein the step of placing the fine ash components in a thickener further comprises pretreating the fine ash components with chemical aids selected from a group consisting of flocculants and coagulants prior to the placement in the thickener.
3 . The process of claim 2 , further comprising adjusting the pH of the fine ash components prior to the placement in the thickener.
4 . The process of claim 1 , where the step of depositing the thickened underflow upon a mechanical dewatering device further comprises pretreating the fine ash component with chemical aids at least one of flocculants and coagulants prior to the depositing upon the mechanical dewatering device.
5 . The process of claim 4 , further comprising adjusting the pH of the fine ash components prior to the step of depositing the thickened underflow upon the mechanical dewatering device.
6 . An in situ process for remediating a surface impoundment to produce a cake bed, the process comprising the steps of:
a. Extracting a slurry from a surface impoundment;
b. Scalping the slurry to separate coarse components and fine components;
c. Placing the fine components in a thickener to create a thickened underflow and an overflow, with overflow being returned to the surface impoundment; and
d. Depositing the thickened underflow upon a mechanical dewatering device selected from the group comprising vacuum belt filter, belt filter press, and plate filter press to create a filtrate and a cake bed, the filtrate being returned the surface impoundment and the thickener, the cake bed consisting of fine components for subsequent transport away from the surface impoundment.
7 . The process of claim 6 , wherein the step of placing the fine in a thickener further comprises pretreating the fine components with chemical aids selected from a group consisting of flocculants and coagulants prior to the placement in the thickener.
8 . The process of claim 7 , further comprising adjusting the pH of the fine components prior to the placement in the thickener.
9 . The process of claim 6 , where the step of depositing the thickened underflow upon a mechanical dewatering device further comprises pretreating the fine component with at least one of flocculants and coagulants prior to the depositing upon the mechanical dewatering device.
10 . The process of claim 9 , further comprising adjusting the pH of the fine components prior to the step of depositing the thickened underflow upon the mechanical dewatering device.