To process Appalachian coal for the market, companies wash and prepare it using water, coagulants, flocculants and surfactants. Coal slurry consists of this chemically treated water and very fine particles of coal, rock and clay.
The rock, coal, and clays contain a wide range of heavy metals including arsenic, lead, cadmium, chromium, iron, manganese, aluminium and nickel—all of which dissolve in the water—and some hydrocarbons and other organic chemicals. While patent law limits the information available about the chemicals used in coal processing, serious concerns about their neurotoxic and carcinogenic effects particularly on workers in the plants [link] have been raised.
Reagents used in processing coal include acrylamides, (some acrylamides are carcinogenic), lime (pH adjuster), natural and modified starches, caustic starch, denatured alcohol, sulfuric acid (pH adjuster), nitric acid (pH adjuster), aluminium sulfate (pH adjuster), iron oxide, diesel fuel and anhydrous ammonia.
There have been very few independent tests of the composition of coal slurry. Since the chemical composition of slurry can be variable depending on the chemical make-up of the coal being processed as well as the chemicals used in a particular prep plant’s washing technique, this means that citizens can have a hard time figuring out exactly what chemicals they are at risk of exposure to.