METHODS AND SYSTEMS FOR CONTROLLING CARBON BURN OUT
Systems and methods for beneficiating a recovered fly ash material and/or recovering fly ash from an impound site are described. The method may include thermally treating a first portion of a recovered fly ash material to form a thermally treated fly ash having a first temperature of at least 1000° F., and contacting the thermally treated fly ash with a second portion of the recovered fly ash material to cool the thermally treated fly ash to a second temperature of less than or equal to 500° F. and form a fly ash product. The fly ash product may have a carbon content less than 8% by weight, based on the total dry weight of the fly ash product.
1 . A method of forming a fly ash-containing product, the method comprising:
thermally treating a first portion of a fly ash-containing mixture to form a thermally treated mixture; and
cooling the thermally treated mixture utilizing a second portion of the fly ash-containing mixture to form the fly ash-containing product, wherein the fly ash-containing product is of lower carbon content than the fly ash-containing mixture, based on a total dry weight of the fly ash-containing product.
2 . The method of claim 1 , wherein the first portion of the fly ash-containing mixture has a carbon content of 10 wt % or more, based on a total dry weight of the first portion of the fly ash-containing mixture.
3 . The method of claim 1 , wherein the first portion of the fly ash-containing mixture comprises wet fly ash.
4 . The method of claim 3 , wherein the first portion of the fly ash-containing mixture has a water content of 40 wt % or less, based on a total weight of the first portion of the fly ash-containing mixture.
5 . The method of claim 3 , wherein the first portion of the fly ash-containing mixture has a water content in the range of 0.1-10 wt %, based on a total weight of the first portion of the fly ash-containing mixture.
6 . The method of claim 1 , wherein the second portion of the fly ash-containing mixture comprises an aqueous solution.
7 . The method of claim 6 , wherein the aqueous solution comprises contact water comprising at least one trace metal contaminant.
8 . The method of claim 6 , wherein cooling the thermally treated mixture utilizing the second portion of the fly ash-containing mixture comprises:
introducing at least a portion of the aqueous solution at least one of before, during, and after thermally treating the first portion of the fly ash-containing mixture.
9 . The method of claim 1 , wherein thermally treating the first portion of the fly ash-containing mixture comprises:
exposing the first portion of the fly ash-containing mixture to a temperature of at least 1,000° F.
10 . The method of claim 9 , wherein in exposing the first portion of the fly ash-containing mixture to the temperature of at least 1,000° F., the temperature deviates less than 100° F. during the exposure.
11 . The method of claim 1 , wherein thermally treating the first portion of the fly ash-containing mixture comprises:
exposing the first portion of the fly ash-containing mixture to a temperature in the range of 1,000-1,300° F.
12 . The method of claim 1 , wherein in thermally treating the first portion of the fly ash-containing mixture, the thermally treated mixture has a temperature of 1,000° F. or more.
13 . The method of claim 1 , wherein cooling the thermally treated mixture utilizing the second portion of the fly ash-containing mixture comprises:
mixing the thermally treated mixture with the second portion of the fly ash-containing mixture.
14 . The method of claim 1 , wherein in cooling the thermally treated mixture, the thermally treated mixture is cooled to a temperature of 500° F. or less.
15 . The method of claim 1 , wherein in cooling the thermally treated mixture, the thermally treated mixture is cooled to a temperature in the range of 200-500° F.
16 . The method of claim 1 , further comprising:
separating the fly ash-containing mixture into the first portion and the second portion prior to thermally treating the first portion.
17 . The method of claim 16 , wherein:
the first portion of the fly ash-containing mixture comprises wet fly ash; and
the second portion of the fly ash-containing mixture comprises an aqueous solution comprising contact water comprising at least one trace metal contaminant.
18 . The method of claim 1 , further comprising:
introducing an auxiliary fuel to the fly ash-containing mixture.
19 . The method of claim 18 , wherein the auxiliary fuel comprises at least one of: natural gas; a liquid fuel; liquid propane; and coal fines.
20 . The method of claim 1 , wherein a temperature difference between the first portion of the fly ash-containing mixture and the second portion of the fly ash-containing mixture is at least 20° F.
21 . The method of claim 1 , wherein the fly ash-containing mixture has a carbon content of 10 wt % or more, based on a total dry weight of the fly ash-containing mixture.
22 . The method of claim 1 , wherein the fly ash-containing mixture has a carbon content in the range of 7-20 wt %, based on a total dry weight of the fly ash-containing mixture.
23 . The method of claim 1 , wherein the fly ash-containing mixture comprises a recovered fly ash material.
24 . The method of claim 23 , wherein the recovered fly ash material is obtained from at least one of: a coal combustion waste source; and an impound site.
25 . The method of claim 1 , wherein the thermally treated mixture has a carbon content of 6 wt % or less, based on a total dry weight of the thermally treated mixture.
26 . The method of claim 1 , wherein the fly ash-containing product has a carbon content of 8 wt % or less, based on a total dry weight of the fly ash-containing product.
27 . The method of claim 1 , wherein the fly ash-containing product is in accordance with ASTM C618 standards, having a loss on ignition (LOI) in the range of 2-6%.