191. A covered facility heats coal to approximately 2,000°F to drive off the volatiles from the coal to produce an activated carbon product. Is this activity considered coal combustion such that Section 313 metal compounds are manufactured in this operation?
Generally, activation of carbon or other organic material involves a two-step process. The first step consists of carbonizing the organic material, which is generally carried out by subjecting the material to temperatures in the range of 500 to 700°C (approximately 930 to 1,300°F). The second step, the activation process, may be chemically performed or it may also be conducted using temperatures typically in the 750 to 1,000°C range (approximately 1,380 to 1,850°F). Both activities occur at temperatures that are below the temperature posed in the question. In any case, while these are high temperatures, these ranges are not equivalent to the temperatures that take place during combustion. Based on available information, the temperature described in the question is not high enough to cause coal combustion. For example, furnaces may operate at temperatures above 1,400°C (approximately 2,550°F). The temperature described in the question may not result in many of the chemical conversions, such as the transformation of metal compounds, which are expected to occur during combustion. However, these temperatures may result in some conversions and the facility would need to determine what takes place based on their best available information and report as necessary.