17-01-2013, 04:27 PM
MANUFACTURE OF AMMONIUM SULFATE FERTILIZER FROM FGDGYPSUM
[attachment=47405]
ABSTRACT
The goal of this study is to assess the technical and economic feasibility of producing
marketable products, namely fertilizer-grade ammonium sulfate and calcium carbonate,
from gypsum produced as part of lime/limestone flue gas desulfurization (FGD) processes.
Millions of tons of FGD-gypsum by-product will be produced in this decade. In this study,
a literature review and bench-scale experiments were conducted to obtain process data for
the production of marketable products from FGD-gypsum and to help evaluate technical
and economic feasibility of the process. FGD-gypsum produced at the Abbott power plant
in Champaign, IL was used as a raw material. The scrubber, a Chiyoda Thoroughbred 121
FGD, produced a filter cake product contains 98.36% gypsum (CaS0,.2H20), and less than
0.01% calcium sulfite (&SO3). Conversion of FGD-gypsum to ammonium sulfate were
tested at temperatures between 60 to 70°C for a duration of five to six hours. The results
of a literature review and preliminary bench-scale experiments are presented in this paper.
INTRODUCTION
The 1990 amendments to the Clean Air Act mandate a two-stage, 10-million ton reduction
in sulfur dioxide emissions in the United States'. Plants burning high sulfur coal and using
FGD technologies must also bear increasingly expensive landfill disposal costs for the solid
waste produced2. The FGD technologies would be less of a financial burden if successful
commercial uses were developed for the gypsum-rich by-products of the wet limestone
scrubbing.
The degree to which FGD-gypsum is commercially used depends on its quality. Currently,
high-quality FGD-gypsum with purity greater than 94% is used mainly to manufacture
construction materials, i.e. stucco and gypsum-plaster, gypsum wall boards, and cement'.
The amount of high quality FGD gypsum could exceed the current demand of the FGDgypsum
industry. Conversion of FGD-gypsum to marketable products could be a deciding
factor in the continued use of high-sulfur Illinois coals by electric utilities. One approach
is to produce cost-competitive ammonium sulfate fertilizer and commercial-grade calcium
carbonate from FGD-gypsum.
Ammonium sulfate is a valuable source of both nitrogen and sulfur nutrients for growing
plants. There is an increasing demand for sulfur in the sulfate form as a plant nutrient
because of diminished deposition of atmospheric sulfur compounds from flue gas emissions
and more sulfur is taken up by plants produced in high yields'. Also, the trend of using
high-nitrogen content fertilizers has pressed incidental sulfur compounds out of traditional
fertilizer. The current market for ammonium sulfate in the United States is about two
million tons per year. It is anticipated that 5 to 10 million tons of new ammonium sulfate
production may be required for fertilizer markets annually to make up for the loss of sulfur
deposition from the increased restriction on acid-rain. The fertilizer industIy appears ready
to accept an added source of fertilizer grade ammonium sulfate to supply sulfur in NPK
fertilizer blends'.
In Phase-I of this study, a literature review and a series of bench-scale experiments were
conducted to obtain process data for the production of ammonium sulfate from FGDgypsum
and to help evaluate technical and economic feasibilities of the process.
EXPERIMENTAL PROCEDURES
Sample of FGD-gypsum and methods of nnnlyses -The Abbott power plant in Champaign,
Illinois operates a Chiyoda Thoroughbred 121 FGD-desulfurization system which produces
one ton of gypsum for every ten tons of coal burned. The FGD-gypsum sample collected
was dried in ambient air for two to four days. The particle size distributions of the sample
were determined using both manual and instrumental methods. In the manual method, the
sample was wet-sieved through a 100 mesh (149pm) screen and then a 200 mesh (74pm)
screen. The weight % of the size-fractional samples were determined after drying.
[attachment=47405]
ABSTRACT
The goal of this study is to assess the technical and economic feasibility of producing
marketable products, namely fertilizer-grade ammonium sulfate and calcium carbonate,
from gypsum produced as part of lime/limestone flue gas desulfurization (FGD) processes.
Millions of tons of FGD-gypsum by-product will be produced in this decade. In this study,
a literature review and bench-scale experiments were conducted to obtain process data for
the production of marketable products from FGD-gypsum and to help evaluate technical
and economic feasibility of the process. FGD-gypsum produced at the Abbott power plant
in Champaign, IL was used as a raw material. The scrubber, a Chiyoda Thoroughbred 121
FGD, produced a filter cake product contains 98.36% gypsum (CaS0,.2H20), and less than
0.01% calcium sulfite (&SO3). Conversion of FGD-gypsum to ammonium sulfate were
tested at temperatures between 60 to 70°C for a duration of five to six hours. The results
of a literature review and preliminary bench-scale experiments are presented in this paper.
INTRODUCTION
The 1990 amendments to the Clean Air Act mandate a two-stage, 10-million ton reduction
in sulfur dioxide emissions in the United States'. Plants burning high sulfur coal and using
FGD technologies must also bear increasingly expensive landfill disposal costs for the solid
waste produced2. The FGD technologies would be less of a financial burden if successful
commercial uses were developed for the gypsum-rich by-products of the wet limestone
scrubbing.
The degree to which FGD-gypsum is commercially used depends on its quality. Currently,
high-quality FGD-gypsum with purity greater than 94% is used mainly to manufacture
construction materials, i.e. stucco and gypsum-plaster, gypsum wall boards, and cement'.
The amount of high quality FGD gypsum could exceed the current demand of the FGDgypsum
industry. Conversion of FGD-gypsum to marketable products could be a deciding
factor in the continued use of high-sulfur Illinois coals by electric utilities. One approach
is to produce cost-competitive ammonium sulfate fertilizer and commercial-grade calcium
carbonate from FGD-gypsum.
Ammonium sulfate is a valuable source of both nitrogen and sulfur nutrients for growing
plants. There is an increasing demand for sulfur in the sulfate form as a plant nutrient
because of diminished deposition of atmospheric sulfur compounds from flue gas emissions
and more sulfur is taken up by plants produced in high yields'. Also, the trend of using
high-nitrogen content fertilizers has pressed incidental sulfur compounds out of traditional
fertilizer. The current market for ammonium sulfate in the United States is about two
million tons per year. It is anticipated that 5 to 10 million tons of new ammonium sulfate
production may be required for fertilizer markets annually to make up for the loss of sulfur
deposition from the increased restriction on acid-rain. The fertilizer industIy appears ready
to accept an added source of fertilizer grade ammonium sulfate to supply sulfur in NPK
fertilizer blends'.
In Phase-I of this study, a literature review and a series of bench-scale experiments were
conducted to obtain process data for the production of ammonium sulfate from FGDgypsum
and to help evaluate technical and economic feasibilities of the process.
EXPERIMENTAL PROCEDURES
Sample of FGD-gypsum and methods of nnnlyses -The Abbott power plant in Champaign,
Illinois operates a Chiyoda Thoroughbred 121 FGD-desulfurization system which produces
one ton of gypsum for every ten tons of coal burned. The FGD-gypsum sample collected
was dried in ambient air for two to four days. The particle size distributions of the sample
were determined using both manual and instrumental methods. In the manual method, the
sample was wet-sieved through a 100 mesh (149pm) screen and then a 200 mesh (74pm)
screen. The weight % of the size-fractional samples were determined after drying.