http://www.epa.gov/epawaste/
The United States Environmental Protection Agency Report we enclose via the above link clearly and definitively identifies Coal Ash, in it's several various forms, for what it truly is:
A readily available raw material resource that can serve as an energy-conserving and pollution-preventing substitute for conventional raw materials in the making of Portland-type cement and Portland-type cement concrete, and in a number of other construction and structural applications.
And, right up front, we want to reproduce one conclusion reached by the EPA, "the Agency", as excerpted from deep within the full document:
"(In) the Agency’s May 2000 Regulatory Determination for fossil fuel combustion wastes, EPA’s risk evaluation of the beneficial use of CCPs in cement and concrete concluded that national regulation under the Resource Conservation and Recovery Act (RCRA) is not warranted."
That said, we caution that the report is lengthy, but well-organized.
And, it deals not just with the solid byproducts arising from our essential use of Coal in the generation of electrical power, but, with an entire class of industrial byproducts which the Environmental Protection Agency awards the well-deserved title:
"Recovered Mineral Components", or, just: "RMC"s.
However, Coal Combustion Products, CCP's, including Fly Ash, Bottom Ash and Flue Gas Desulfurization wastes, in their total, comprise by far the largest body of "RMC"s treated by the US EPA herein; and, this entire report can be treated as a manual on how and where those CCP's, or, as we prefer, "Coal Utilization Byproducts", "CUB"s can be profitably and constructively utilized and consumed, with broad and beneficial environmental and economic impacts.
Due to the length of the report, our excerpts, which we've tried to summarize and condense in as an intelligible and meaningful a way as possible, might seem a bit disjointed and poorly organized.
Compounding that will be the fact that we're not including page numbers, in a vain attempt to make the excerpts appear more of a closely-related narrative concerning the value of CUB's than, due to it's length and the inclusion of a few other "RMC"s, it actually is.
However, if we Coal partisans take from it what we should, as we have in our excerpts attempted to do, it can be seen as a manual, a guidebook, on how and where we can start to more intensively promote and market our Coal Utilization Byproducts, in ways and places that can both enhance our Coal Country economy and improve our national environment.
Comment follows what are, in fact, exquisitely brief excerpts from the initial link above to:
"Study on Increasing the Usage of Recovered Mineral Components in Federally Funded Projects Involving Procurement of Cement or Concrete
United States Environmental Protection Agency in conjunction with the U.S. Department of Transportation and the U.S. Department of Energy
Report to Congress; June 3, 2008; EPA530-R-08-007
Executive Summary: Section 6017(a) of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users, P.L. 109-59, Aug. 10, 2005 (SAFETEA-LU), directs the U.S. Environmental
Protection Agency (EPA or the Agency) to, '…conduct a study to determine the extent to which procurement requirements, when fully implemented…may realize energy savings and environmental benefits attainable with substitution of recovered mineral components in cement used in cement or concrete projects.'
SAFETEA-LU directs EPA to submit a report to Congress ... that addresses the following requirements:
(A) Quantify (i) the extent to which recovered mineral components are being substituted for portland cement, particularly as a result of current procurement requirements; and (ii) the energy savings and environmental benefits associated with that substitution;
(B) Identify all barriers in procurement requirements to greater realization of energy savings and environmental benefits, including barriers resulting from exceptions from current law; and:
(C) (i) Identify potential mechanisms to achieve greater substitution of recovered mineral components in types of cement and concrete projects for which recovered material components historically have not been used or have been used only minimally; (ii) evaluate the feasibility of establishing guidelines or standards for optimized substitution rates of recovered material component in those cement and concrete projects; and (iii) identify any potential environmental or economic effects that may result from greater substitution of recovered mineral components in these cement and concrete projects.
Energy savings and environmental benefits associated with substitution. Recovered mineral component (RMC) use yields positive environmental benefits through lower resource consumption. To overcome procurement data limitations, for ground granulated blast-furnace slag (GGBFS), coal combustion fly ash (coal fly ash) , and silica fume, the report derives estimates of their use in Federal projects by roughly apportioning total volumes to Federal and non-Federal projects (based upon the estimated proportion of total cement demand related to federally-funded projects).
For the years 2004 and 2005, our life cycle analysis indicates that the use of GGBFS, coal fly ash, and silica fume in Federal concrete projects alone resulted in significant reductions in greenhouse gas (GHG) emissions, criteria air pollutants, and energy and water use. For these two years combined, the analysis indicates reduced energy use of 31.5 billion megajoules, avoided CO2 equivalent air emissions of 3.8 million metric tons, and water savings of 2.1 billion liters. The report further illustrates how these benefits may accrue over a longer time period
Coal combustion fly ash:
A finely-divided mineral residue from the combustion of ground or powdered coal in coal-fired power plants.
Partial replacement for portland cement in concrete applications. Can be used as a raw material in the production of portland cement clinker or as an inter-ground or blended supplementary cementitious material (SCM) in the production of blended cements.
Benefits of Use:
Use of coal combustion fly ash in concrete results in environmental benefits from avoided virgin materials extraction and manufacturing of portland cement. These benefits include reduced energy use and associated GHG emissions, reduced water use and reduced air pollution.
In addition, certain performance benefits can be attained through the use of fly ash in cement, including greater workability in the mixed concrete and higher strength and increased longevity in the finished product. Also, (such use of Coal Ash) creates more concrete from the same amount of portland cement.
(Coal Ash can) also be used as a raw material in the production of portland cement clinker or as an inter-ground or blended supplementary cementitious material (SCM) in the production of blended cements.
Cenospheres:
Small, inert, lightweight, hollow, "glass" spheres composed of silica and alumina and filled with air or other gases. They occur naturally in coal fly ash (and are used) in concrete production to increase concrete's strength and (decrease) shrinkage and weight. Cenospheres may also be used in a wide variety of materials, from paints and finishes to plastics and caulking.
Flue gas desulfurization (FGD) gypsum:
FGD by-products are generated by air pollution control devices used at some coal-fired electric power plants. Forced oxidation wet FGD systems create gypsum as a by-product. Replacement for natural gypsum in wallboard production and grinding with clinker to produce finished cement.
Flue gas desulfurization (FGD)dry scrubber material:
Dry FGD systems remove sulfur dioxide (SO2) from coal-fired power plant flue gas. Main constituents of resulting byproduct include calcium sulfite, fly ash, portlandite, calcite, calcium sulfate. Dry FGD material is used in concrete mixes and products as a substitute aggregate material.
Dry FGD material may also be used for embankments and roadbase compositions.
Power plant bottom ash:
A coarse, solid mineral residue that results from the burning of coal in utility boilers. Used as aggregate in concrete, or for other aggregate uses such as compacted base course.
Also used as raw material in cement clinker manufacture as alternative source of silica, alumina, iron,
and calcium.
Power Plant Boiler slag:
A coarse, hard, black, angular, glassy material, produced from slag in wet-bottom boilers. Owing to its abrasive properties, boiler slag is used almost exclusively in the manufacture of blasting grit; can also be used as raw feed component to make cement clinker (and is also) useful in lightweight concrete and concrete block applications.
As a raw material in cement manufacture, the bottom ash can supply some of the necessary oxides (thus saving on virgin raw materials), and can do so at a lower energy cost and with reduced emissions than for some virgin materials.
As (illustrated in accompanying tables) the use of RMCs can decrease the demand for certain virgin
materials and decrease the demand for the use of portland cement. This leads to decreased resource consumption, namely energy and water. Lower resource consumption can yield, in turn, reductions in various pollutants and other positive environmental impacts, such as a reduction in GHG emissions.
To assess these potential benefits further, this analysis provides quantified estimates of the environmental impacts and benefits ... .
Consistent with the Congressional mandate to examine "recovered mineral components in cement used in cement or concrete projects," these estimates focus specifically on the impacts resulting from the use of these three mineral components as a partial replacement for, or supplement to, portland cement in Federal construction projects involving concrete.
The assessed metrics include resource savings (e.g., reduced energy and water consumption), various avoided priority air pollutants (e.g., NO2, PM10, SOx, Hg, Pb), and various measures of avoided GHG emissions (e.g., CO2, CF4, CH4, N2O), which we further translate into equivalent metrics of avoided gasoline and oil consumption, and vehicles removed from the road.
Additionally, unquantified benefits may be associated with improved performance of concrete and resulting decreases in the materials and energy needed to repair, replace, and upgrade road beds.
(As we've documented, without linking to our prior reports, cement and concrete made with Coal Ash can be stronger, more durable and more chemically resistant than Portland-type cement and concrete.)
(The) use of coal fly ash alone may result in 3.8 million metric tons of avoided carbon dioxide equivalent in the years 2004 to 2005. This savings is equivalent to removing 0.8 million passenger cars from the road for one year.
Through the year 2015 under this scenario, we estimate that the use of such RMCs in Federal concrete projects may result in reduced CO2 emissions of over 25.7 million metric tons, which is equivalent to removing 5.7 million passenger cars from the road for one year.
(Note that is just in "Federal concrete projects".)
EPA advises procuring agencies to prepare or revise their procurement programs for cement and concrete, or for construction projects involving cement and concrete, to allow for the use of coal fly ash (and) cenospheres ... as appropriate.
Recovered materials are frequently used as substitutes for or supplements to portland cement when mixing concrete. Some recovered materials can also be used in the manufacture of portland cement itself, by replacing other raw materials used in making clinker (the intermediate product in portland cement manufacturing) and also in the later blending stages of the cement manufacturing process. The blended cement produced by this process is then used in concrete in place of straight portland cement. Finally, many recovered materials can be used as a direct substitute for the aggregate (i.e., non-cement) portion of concrete.
All of the materials examined in this section are currently being reused as material substitutes in the cement manufacturing process or the concrete mixing process (or both). The degree to which these materials are being used in cement and concrete production ranges from relatively low (i.e., approximately 10% to 15%) to 100%. When used appropriately, these materials enhance the performance, handling, and durability of finished concrete products ... .
In addition, the use of these materials in cement and concrete production yields a number of environmental and economic benefits ... . Furthermore, using RMCs helps limit the amount of virgin material that must be mined or imported to meet U.S. demand for cement.
According to the ACAA (American Coal Ash Association) survey data, of the 64.2 million metric tons of coal fly ash produced in the United States in 2004, approximately 40% (25.5 million metric tons) was beneficially used, while the remaining 60% (approximately 38.8 million metric tons) was disposed of in land disposal units. Utilization of coal fly ash has increased through 2006 to nearly 45%.
Both Class C and F coal fly ash can serve as substitutes for conventional materials in construction projects.
The most common beneficial use of coal fly ash is as a Supplementary Cementitious Material (SCM) in concrete. Coal fly ash is also used as a raw material in the production of cement clinker and as an additive to blended cements. The consistency and abundance of coal fly ash in many areas present unique opportunities for use in many construction applications, including pavements and highway and transportation structures, and can generate environmental benefits when used as a replacement for virgin materials (e.g., portland cement).
Certain performance benefits can be attained through the use of coal fly ash in concrete, including greater workability, higher strength, and increased longevity in the finished concrete product.
Specifically:
- Spherical particle shape allows the coal fly ash to flow and blend freely in mixtures improving mixing and handling.
- Ball bearing effect creates a lubricating action when concrete is in its plastic state; as a result, pumping is easier because less energy is required and longer pumping distances are possible.
- Strength increases as it continues to combine with free lime, increasing the structural strength over time.
- Reduced permeability and increased durability.
- Reduced shrinkage from the lubricating action of coal fly ash reduces water content and drying shrinkage.
- Reduced heat of hydration reduces thermal cracking (e.g., for dams and other mass concrete placements).
- Improved workability makes concrete easier to place.
- Where sharp, clear architectural definition is easier to achieve, finishing is improved with less concern about in-place integrity
- Reduced susceptibility to chemical attack (e.g., sulfate attack).
Cenospheres are very small (10 to 350 μm in diameter), inert, lightweight, hollow, “glass” spheres composed of silica and alumina filled with air or other gases. They occur naturally in coal fly ash and are recovered from the ash for use as aggregate (filler) in many applications such as concrete and plastic products.
Cenospheres are not usually intentionally manufactured (and, their) principal source is coal fly ash.
The percentage of cenospheres used in concrete varies depending on the application and desired performance characteristics of the concrete. However, according to industry sources, the typical content of cenospheres in concrete ranges from 10% to 40% by volume.
Concrete containing cenospheres also often contains coal fly ash.
ACAA reports that approximately 5,200 metric tons of cenospheres were sold in the United States in 2004, 7,00042 metric tons were sold in 2005, and 5,000 metric tons were sold in 2006. Actual annual cenosphere production is much greater than the volumes being sold, as not all cenospheres are separated from the coal fly ash for use.
When incorporated into concrete mixes as fillers or extenders, cenospheres increase the strength of the concrete and decrease shrinkage and weight.
Cenospheres are 75% lighter than other minerals currently used as fillers, which reduces the final concrete mix’s weight and increases their thermal stability and overall durability. Cenospheres can be used in concrete with other recovered materials, such as coal fly ash
Flue Gas Desulfurization (FGD) Materials are generated by air pollution control devices used at any sulfur dioxide (SOx ) producing emissions source that has an appropriate scrubber, like some coal-fired electric power plants. Power plants and other types of facilities (e.g., some cement plants) use a number of FGD processes to control sulfur oxide (SOx) emissions from the combustion of coal. FGD processes spray lime or limestone reagents into the exhaust gas, which removes and converts the SO2 to sludge or a semi-sludge byproduct.
According to ACAA, U.S. coal-fired power plants produced approximately 11.0 million metric tons of FGD gypsum in 2006, with approximately 8.7 million metric tons being reused, approximately 79%. Of this amount, approximately 81% is used in wallboard manufacturing, about 16% is used in concrete, concrete products and grout, and about 3% is interground with clinker to produce finished cement.
Power plant bottom ash is a coarse, solid mineral residue that results from the burning of coal in utility boilers. The material is removed from the bottom of the boilers either in a wet or dry state and transported to handling areas by conveyor or pipe. Bottom ash has a similar chemical composition to coal fly ash, but is produced in size grades ranging from fine sand to medium gravel. Although larger in particle size, bottom ash has a smaller reactive surface area than coal fly ash. Because of its much larger particle sizes, bottom ash has a smaller total reactive surface area, for the same weight, as coal fly ash. With this and other characteristics, bottom ash does not have sufficient cementitious properties to be used as a replacement for cement, although it can be used in clinker manufacture as an alternative source for silica, alumina, iron and calcium.
Bottom ash can be used as a replacement for aggregate in concrete and is usually sufficiently well graded in size to avoid the need for blending with other fine aggregates to meet gradation requirements. The porous surface structure of bottom ash particles make this material less durable than conventional aggregates and better suited for use in base course and shoulder mixtures or in cold mix applications, as opposed to wearing surface mixtures.
The porous surface structure also makes this material lighter than conventional aggregate and useful in lightweight concrete applications. Bottom ash also can be used as a raw material in clinker production as an alternative source of silica, alumina, iron, and calcium.
(Note, that, in cement manufacturing) substituting one metric ton of coal fly ash results in 0.72 metric tons of avoided CO2 equivalent emissions,
Results indicate that the beneficial use of coal fly ash in 2004 and 2005 resulted in energy savings valued at approximately $0.7 billion, and water savings valued at approximately $1.2 million.
Performance and quality concerns are known to prevent some potential RMC users from incorporating these materials into their portland cement or concrete products. These concerns may be related more to traditional terminology than actual performance. The term “recovered mineral content” refers to a material with a positive or beneficial use, regardless if the material was originally generated as a byproduct or waste. However, in many states, potential users and others appear to equate these materials with “wastes,” that do not or cannot have the same quality attributable to a virgin or manufactured material. Most RMCs, however, when used properly, will preserve or enhance final product quality and durability.
(Some amount of educational effort is required, in other words.)
Texas was also selected as a pilot state for an in-depth review of its CCP programs, policies, and use practices because of its progressive approach to CCP utilization and its support network to implement such activities.
(Why is "Texas" considered to have a "progressive approach to CCP utilization", while West Virginia and Pennsylvania are not?)
Although the Texas state review discussed barriers for all applications, we summarize only those specific to CCP use in portland cement and concrete:
- Virtually all of the utilities, ash marketers, and ready-mix producers mentioned attitude and education as key barriers. District and local highway personnel, architects, engineers, and contractors cited unfamiliarity, lack of knowledge, or unwarranted negative feelings toward CCPs as barriers to greater CCP utilization.
Studies have noted the sub-optimal geographic location of RMC supplies, particularly coal fly ash and bottom ash. The best example of the lack of local availability is in California, where essentially no coal-fired power plants and no blast furnaces exist. However, depending on the size and scale of the project, the lack of proximate coal fly ash and related transportation costs may be overcome. For example, the large CalTrans Bay Bridge project imported coal fly ash from Washington and Wyoming, and the additional cost of transportation was minimal when compared to the entire project budget.
Another barrier to the expanded beneficial use of RMCs concerns the safety and health risks, real or perceived, associated with these materials, i.e., the environmental risks associated with exposure to these industrial materials if they enter the environment through leaching into soil or other pathways.
However, targeted risk analyses conducted to-date indicate that risks associated with the identified RMCs in cement and concrete are likely to be insignificant.
For example, in the Agency’s May 2000 Regulatory Determination for fossil fuel combustion wastes, EPA’s risk evaluation of the beneficial use of CCPs in cement and concrete concluded that national regulation under the Resource Conservation and Recovery Act (RCRA) is not warranted.
Findings from these analyses did not identify significant risks to human health and the environment associated with the beneficial uses of concern. In addition, we identified no documents providing evidence of damage to human health and the environment from these beneficial uses. Our overall conclusions from these efforts, therefore, are that encapsulated applications, including cement and concrete uses, appear to present minimal risk.
(Included figures show) the locations of the 39 portland cement plants using coal fly ash as a raw feed
in the manufacture of clinker and the 3 plants blending coal fly ash into finished cement products.
(Very sadly, the map shows that there are none of the above in West Virginia or Pennsylvania. While New York has two and Florida has four.)
(Another included figure) shows the locations of portland cement facilities grinding and blending flue gas
desulfurization materials with clinker to produce finished cement products."
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And, again, West Virginia has none; but, Pennsylvania does at least have one.
Further, and again, we do regret the somewhat rambling and disjointed nature of our excerpts. The length and scope of the full, comprehensive report confounded our efforts to do a better job for you.
But, the full document does demand a full read and thorough study by anyone genuinely interested in the health of, both, our various Coal Country state economies and our national environment.
Coal Utilization Byproducts are herein thoroughly demonstrated to be valuable raw material commodities.
They can serve to displace natural raw materials in basic manufacturing processes, thereby reducing disruption of the natural environment through extraction of those raw materials; they can reduce emissions of Carbon Dioxide in cement- and concrete-making processes while enhancing the properties of the finished products; and, they can serve as an income source for the states that produce them.
Furthermore, again and finally, concerning Coal Utilization Byproducts, the United States Environmental Protection Agency, more than a decade ago: "concluded that national regulation under the Resource Conservation and Recovery Act (RCRA) is not warranted".