Back to Library


Volume 15, Number 1           A Gossman Consulting, Inc. Publication       May 2010

The Negative Environmental Impact of Classifying Coal Combustion Products as Hazardous Waste


David Gossman


Proposals by EPA to reclassify coal combustion products (CCPs) as hazardous waste are likely to have a significant negative impact on reuse and recycling of these materials. Assuming there are exemptions for reuse and recycling there will be a negative stigma associated with the use of these materials in a wide variety of manufacturing processes and end uses. This will be particularly true for end uses that are more directly connected with individual consumers vs. companies already dealing with hazardous materials. The result will be a significant reduction in environmentally desirable recycling and reuse of CCPs. Any comparison of the reuse and recycling of CCPs with other recycled industrial waste that would otherwise be considered a hazardous waste reveals significant differences in nationwide quantities, recycling/reuse methodology and/or end use that makes this an “apples and oranges” comparison. It is also important to understand that CCPs substitute for traditional low cost raw materials. Any association with hazardous wastes creates a large disadvantage for CCPs in the market.

Coal combustion products (CCPs) is a collective term referring to any material or residue produced from the combustion of coal or cleaning of stack gases regardless of ultimate commercial application or disposal. Specifically, it includes fly ash, bottom ash, boiler slag, fluidized bed combustion ash, and flue gas desulfurization material.

 CCPs, when used in various applications, can result in benefits of which many probably aren’t aware. Environmental benefits include the reduction of greenhouse gas emissions, reduced land disposal requirements, and reduced use of raw materials. There are economic advantages as well, including reduced costs of materials disposal, increased revenue from the sale of CCPs, and savings from substituting them for other, more expensive materials. And the use of those materials can result in performance benefits—CCPs can enhance other products by strengthening them and making them more workable. For example, fly ash as a partial substitute of Portland cement in concrete, produces pavements that last longer.

 The last example in the prior paragraph is just one way that CCPs are used in the cement/concrete industry. In addition to their use as a substitute for Portland cement in concrete production, as previously mentioned, CCPs can also be used to substitute for some of the raw materials used to make Portland cement – both in the clinker phase in cement kilns and in the finished product phase by providing calcium sulfate (gypsum) for use in controlling the set time of Portland cement.

 If CCPs are stigmatized by being classified as hazardous waste, even if it is only when they are disposed or land filled, use in the cement industry will decline in order to avoid the stigma associated with anything considered “hazardous” and “waste”. Other uses that are likely to be stigmatized include use as road bed material, agricultural uses, soil stabilization, wallboard in construction, and waste treatment.

 Other Recycled Materials

 Advocates of the idea of classifying CCPs as hazardous waste point to a wide variety of exemptions in the RCRA regulations for materials that are recycled and reused in order to argue that CCPs users’ arguments on “stigma” are invalid.  They argue that markets for such reused products have not been adversely affected, so one cannot assume markets for CCPs would be adversely affected if CCPs are declared to be hazardous waste.

 Exemption examples include solvents that are recycled, solvents that are used as fuels, sulfuric acid that is reclaimed and recycled, and metals that are recycled back to a wide variety of end uses. In the vast majority of cases these materials require significant processing, distillation, chemical treatment, or smelting to be turned from a waste into a product. Further, in many of these cases the end product is still a hazardous material and is sold back into a market that is otherwise purchasing hazardous materials – with all of the risks and associated management practices that they would be using to handle virgin materials.

 Consider the example of recycled solvents. Waste solvents are generally classified as EPA hazardous waste F001, F002, F003, F005 and/or D001. These listed and characteristic hazardous wastes must be managed as hazardous waste up until they have been recycled. At that point they cease being hazardous waste and are considered products. Most of these waste solvents are recycled using various forms of distillation that remove contaminants and leave the solvent suitable for reuse. Often they are sold back to the same companies that generated them as wastes in the first place. Most are still considered hazardous under DOT shipping regulations and users handle them as hazardous materials just as they would virgin solvents. The distillation residues are still considered hazardous waste and is most often used in a small number of cement kilns as hazardous waste fuel.

 Among the other previously mentioned hazardous wastes that have exemptions sulfuric acid is recycled by feeding it to a sulfuric acid furnace where it is thermally broken down and then reconstituted as sulfuric acid, indistinguishable from the sulfuric acid produced from other sources of sulfur. Obviously sulfuric acid is then sold into the market as a hazardous material.

 Metal bearing hazardous waste is often fed to smelters where the metals are thermally extracted from contaminants. Alternatively, some metals are recycled by using chemical extraction and purification methods. Such metals are resold into the chemical market place – often as hazardous materials depending on the nature of the metal or metal salt. Some of these recycled metal salts are used in fertilizers but they must meet strict controls on contamination.

 Solvents that are used as fuels are most often managed as hazardous waste throughout the handling and combustion process in a cement kiln or other hazardous waste permitted combustion device. A very small fraction of the waste solvents are “clean” enough to fall into a clean fuel exemption where they are burned in an industrial boiler, often at the same site where they are generated. This exemption does not eliminate the fact that these materials often continue to be  treated as hazardous materials since they are frequently flammable and some are considered toxic. They do not openly enter a commodity based nationwide market place.

 An “Apples and Oranges” Comparison

 CCPs are produced throughout the United States and currently find use in a variety of products that are ultimately used in homes, roads and widespread construction products. The current quantities of materials that would otherwise be classified as hazardous wastes are far more limited than CCPs.

 CCPs are most often used as is without any further processing other than being blended with other intermediates depending on the end use. Even when used as a feedstock, such as in a cement kiln, they require no processing prior to being fed into the cement kiln system. This is in contrast to currently recycled hazardous wastes such as solvents that require distillation or sulfuric acid which is elementally disassociated and reformed in a sulfuric acid furnace. While there may be relatively small quantities of materials that would otherwise be identified as hazardous wastes going directly into end use applications; quantities, markets and characteristics of these materials make any comparison to CCPs questionable.

 There are readily available nonhazardous alternatives to CCPs available in the market place. This is not the case for the afore mentioned hazardous wastes that are currently recycled and reused. When a user has a choice they will preferentially use something that is not identified by EPA as a hazardous waste when disposed.

 Factors Impacting Alternative Fuel and Material Use in the Cement and Concrete Industries

 Over the last 30 years most US cement production has moved toward the active use of a wide variety of alternative fuels. Despite attempts by over 30% of the US cement industry to obtain permits to burn hazardous wastes only about 10% if the industry uses these wastes as fuel despite a substantial financial incentive. This is a result of the significant regulatory, commercial and public perception barriers that have arisen during this same time frame. There have been repeated attempts by non-governmental organizations (NGOs) to create barriers to prevent this environmentally beneficial recycling and reuse activity which has been shown repeatedly to have no negative impacts on either product or the environment. These include lobbying for labeling requirements and pressure on individual retailers to not carry the products from plants using these hazardous waste fuels. There can be little doubt that if CCPs are identified by EPA as hazardous wastes that such labeling would encourage similar actions by NGOs relative to the use of CCPs in the cement production process.

 In the same way that cement kilns use a wide variety of alternative fuels they also use a wide variety of alternative raw materials. No cement kilns are currently using any alternative raw materials that are derived from hazardous wastes. If CCPs are declared a hazardous waste, even under limited disposal scenarios, the negative perceptions that would create are likely to reduce the potential market for CCPs in cement kilns to the relative level of hazardous waste used as fuel in cement kilns at best – a huge decrease from current levels of use.


 The idea that hazardous wastes (or what would be hazardous waste if disposed) might be used in the foundation or wall boards of one's home is more than adequate incentive for the cement and construction industry to reject these materials if EPA alters the current classification of CCPs. Comparisons with the limited scope recycling and reuse of other hazardous wastes are not valid comparisons. Most of these wastes are used to create industrial products which are themselves hazardous and most of them require considerable processing in order to become products. CCPs are products as they are produced and enter a wide variety of applications as direct substitutes for traditional raw materials.

Ultimately attempts to control CCPs when disposed in landfills by classifying these materials as hazardous waste are likely to increase the amount of this material going into landfills and thus increase risks from landfilling this material – opposite the intended effect.