Coal has provided a reliable source of power to humanity for thousands of years. Standards have helped make it part of today’s mix of energy sources.
By Kathy Hunt
Jun 30, 2025
For thousands of years, it has served as a source of heat and energy for activities such as bathing, cooking, forging, and smelting. In Northwestern China, archeological excavations point to the large-scale use of this organic rock over 3,600 years ago, while ancient fragments suggest that it was intermittently burned over 10,000 years ago. Plentiful and consistent, it powered the 19th century Industrial Revolution in the United Kingdom, continental Europe, and the United States, moving economies and societies from agrarian to manufacturing based.
Along with its practical purposes, this combustible substance has sparked imaginations, inspiring plays, films, books, paintings, and songs. Embraced by some and criticized by others, its use and impact on the environment and humankind have been debated for decades. What fossil fuel could have such a long and complex world history? Coal.
In the Modern Era, several inventions increased the global need for coal. Once such driver was the steam engine. Introduced in 1712, coal-powered steam engines were an integral component of trains, ships, foundries, and mines for centuries.
The production of steel and the use of coke likewise contributed to the clamor for coal. Coke is the porous carbon substance created by the destructive distillation of coal. This occurs when coal is heated to between 1,000 and 1,200 degrees Celsius in an oxygen-free container. Because it burns hotter than coal, coke is used to smelt iron ore. It also acts as a reducing agent in the extraction of metals.
Historically, coal-rich countries responded to the need for coal and coke as it continued to grow. In the early 1700s, the U.K. mined roughly 3 million tons of coal. A century later, that number soared to 30 million tons. As a result of its reliance on wood for heat and a dearth of energy-consuming factories, the U.S. didn’t begin mining coal in earnest until the mid 1800s. Once it began, though, it quickly caught up to the production of other countries. In 1850, the U.S. produced 8 million tons of coal. By 1870, its output had quintupled to 40 million tons.
More coal supplies meant more applications for coal, including fueling gaslights in towns and cities. In 1882, the U.K. fired up the world’s first coal-fired power plant; it closed the last plant of its kind in October 2024, making it the first major economy to step away from coal power. The U.S. also opened its first coal-fired power plant in 1882, in New York City. Unlike the U.K., in 2024, the U.S. still had 204 operational coal-fired plants.
120 Years of Coal Standards
With the prevalence of this fossil fuel came the desire to ensure the safety and performance of not only coal but also coke and the fuels resulting from the combination of coal or coke with other substances. In 1904, ASTM International created the committee on coal and coke (D05). Current D05 chair Stephen Smith notes that the coal and coke committee was ASTM’s second committee, arising from the committee on steel, stainless steel, and related alloys (A01).
“Imagine it’s 1898. The railroads are expanding westward, and the trains are being built at higher and higher steam pressures, higher and higher speeds. The steel used in the rails that the trains ran on was not standardized. In places where the rails were soft, trains could slip off the tracks,” says Smith, a consultant with Coalsmith Consultants and retired senior chemist with the Tennessee Valley Authority. “Standards for steel were needed, so ASTM formed its first committee. And what is used to make steel? Coal and coke. So another committee was formed.”
Today’s coal and coke committee originated from three related groups: committee J on standard specifications for foundry coke; committee O on standard specifications for coal; and the original committee E04, then known as the committee on sampling and analysis of coal (E04 worked with the American Chemical Society on the sampling and analysis of coal). In 1921, the three committees joined together under D05.
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Among the committee’s earliest standards was the classification of coals by rank (D388). It established coal categories based on the degree of metamorphism, or progressive alteration, of coal during the time that it was buried. Published in 1934, the standard covers a range of physical and chemical characteristics that aid in predicting the behavior of coal in mining, preparation, and use. Long-standing member Lou Janke explains that the standard helped establish economic opportunities for coal and “prompted a comprehensive and reliable basis for the classification of coal reserves.”
The standard test method for grindability of coal by the Hardgrove-Machine Method (D409) is another venerable standard. Dating back to 1951, the test method provides a measurement of the grindability of a particular quality of coal relative to a standard quality. It can be used to evaluate the yield or energy input, or both, required to grind or pulverize coal. This can affect a range of processes such as the combustion, coke-making, liquefaction, and gasification of coal. The International Organization for Standardization (ISO) cites D409 as a normative reference for ISO 5074 hard coal—determination of Hardgrove grindability index.
The grindability standard requires users to have a reference material – a prepared coal sample – to calibrate their equipment. In the past, Pennsylvania State University, under the U.S. Department of Energy, produced the reference materials, a task that was recently assumed by Quality Assurance Resources (QAR), a division of Standard Labs.
Influences for Coal and Coke Standards
Periodically, organizations will cite ASTM standards cited as normative references, as is the case with D409/ISO 5074. Other times, ASTM will reference the standards of other organizations, such as with the standard practice for collection and preparation of coke samples for laboratory analysis (D346) and coal and coke—manual sampling (ISO 18283).
“At ISO, the sampling subcommittee SC4 put a lot of work into the manual sampling standard for coal and coke, ISO 18283. ASTM had a very old coke sampling standard [D346],” says Paul Reagan, subcommittee chair of the U.S. Advisory Committee to ISO/TC 27 on coal and coke (D05.27) and liaison to the American National Standards Institute (ANSI) for ISO. “When it came up for review, and since 18283 had gone through all this work, ASTM reciprocated by making a normative reference to ISO 18283.”
Revisions to D346 were recently balloted and passed. They listed ISO 18283 and ISO 13909 (mechanical sampling) as the governing documents specifying requirements for the sampling and preparation of metallurgical coke.
“[Normative referencing] goes both ways, and that’s what we consider to be exactly what should happen,” says Reagan. “Whoever has the better standard in the judgment of the experts, that’s the standard that should be used.”
Occasionally, standards will be influenced by, but not superseded by, another organization’s standard. Updated in 2024, the standard practice for determination of gas in coal—direct desorption method (D7569) was based on a U.S. Bureau of Mines test method from the early 1980s, says former committee chair Ron Graham.
“This method is useful in understanding the amount of methane that could be released from a coal seam, either during the mining process, during methane-extraction prior to mining, or independent of mining,” he says.
Changing Times
Times and technologies seem to change rapidly. Even so, the coal and coke committee has kept pace by writing new standards and revising older ones to reflect current advances and concerns.
“One of the nexus points was in the 1980s with the automation of instrumentation,” Janke says. “D05 recognized that the availability of automated instrumentation with computerized operation and data-handling capabilities could address the need for rapid and reliable test methods for screening coals for end use. These alternatives to the classical standards that had served the coal industry for so many years introduced significant gains in measurement reliability and productivity.”
Introduced in the early 1980s, the standard test method for sulfur in the analysis sample of coal and coke using high-temperature tube furnace combustion (D4239) was the first automated test method. Janke says the standard played a key role in supporting regulatory requirements for SOx (sulfur oxides) emissions. When sulfur oxides react with nitrogen dioxide (NO2), the event produces sulfuric acid, a contributor to acid rain, air pollution, and climate change.
Vice chair Jay Albert says that in the last 20 years, the coal and coke committee’s focus has shifted from straight utilization of coal for power to the environmental aspects of coal usage. “To that end, in 2020, we published a standard related to testing gypsum (calcium sulfate) used for desulfurizing the flue gas from power plants,” says Albert, technical director at PARR Instrument Company and subcommittee chair of methods of analysis (D05.21).
“We test the material for various qualities and then use it to make wallboard.”
The standard to which he refers is the test method for the analysis of flue gas desulfurization solids by macro thermogravimetric analysis (D8339).
Smith adds, ““Basically a new method was developed for analyzing flue gas desulfurization (FGD) solids, using a commonly available coal analyzer. FGD solids used for wallboard can’t have much evolution of carbon dioxide.”
The subcommittee on major elements in ash and trace elements of coal (D05.29) has two standards pertaining to mercury emissions. They are the standard test methods for total mercury in coal and coal combustion residues by acid extraction or wet oxidation/cold vapor atomic absorption (D6414); and the standard test method for total mercury in coal and coal combustion residues by direct combustion analysis (D6722). These standards, along with the standard test method for determination of chlorine in coal by oxidative hydrolysis microcoulometry (D6721), moved from inception to acceptance in less than two years, Janke says.
Presently, the subcommittee is working on another chlorine standard, the new test method for determination of total chlorine in coal by X-ray fluorescence (WK85129).
“Knowing the chlorine in coal is important for determining other aspects of coal quality,” Albert says. “Chlorine influences how other pollutants, such as mercury, are dispersed from the burning of coal.”
Smith notes that prior to this work item, chlorine measurement of whole coal using X-ray fluorescence (XRF) had never been under an interlab study (ILS) to determine the accuracy of the XRF measurement of chlorine in coal. The task group is finalizing the ILS now and also plans to include sulfur in the precision and bias statement of the new XRF standard.
Rare Earth Elements and Critical Minerals
According to the U.S. Energy Information Administration (EIA), U.S. recoverable coal reserves could last for roughly 422 years. Yet, in recent times, coal production in the U.S. has declined precipitously. In 2008, it peaked at 1,171.5 million short tons but dropped to less than half that amount, 578 million short tons, in 2023, the EIA reported. The following year saw another drop in production to an estimated 512 million short tons. Environmental regulations and cheaper energy sources, such as natural gas, are commonly cited as reasons for coal’s decline.
Nonetheless, politicians and other officials contend that the country’s coal industry will rebound. They point to the U.S.’s vast coal reserves, recent easing of environmental regulations for coal-fired plants including a deadline extension for compliance with the EPA’s mercury and air toxics standards, and overwhelming demand for energy. They also indicate the presence of rare-earth elements and critical minerals in coal. These are essential to technology and energy production.
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“There is only a certain amount of rare-earth elements and critical minerals available, and it’s become an existential crisis for the U.S. economy. They need access to these things,” Janke says. “Coal contains almost every natural element in the periodic table, so it can contain rare earth elements, possibly in concentrations that you could extract.”
He says this is why the committee revised the standard test methods for determination of trace elements in coal, coke, and combustion residues from coal utilization processes by inductively coupled plasma atomic emission spectrometry, inductively coupled plasma mass spectrometry, and graphite fur (D6357) to include the determination of rare-earth elements. A subset of critical minerals, they are thought to include the following: cerium; dysprosium; erbium; europium; gadolinium; holmium; lanthanum; lutetium; neodymium; praseodymium; samarium; scandium; terbium; thulium; ytterbium; and yttrium.
Specific test methods for the determination of rare-earth elements in coal and coal combustion residues are outlined in the standard. But for now, the viability of rare-earth elements remains uncertain.
“There has been a lot of chatter about rare earth,” Reagan says. “Whether there really is commercially recoverable quantities in coal is yet to be determined.”
The Future
“These are challenging times for the coal and coke industry and for those seeking to maintain the relevancy of coal and coke industries,” Graham says. “The switching of energy production from a hydrocarbon base to renewable sources is happening, regardless of individual or corporate philosophies or beliefs.” Graham is the recipient of several ASTM awards, including the Ted Linde Leadership Award and Award of Merit.
“Earth has limited resources. Each ton of coal burned to produce energy and carbon dioxide removes that resource for the generation of new technologies and products that we may not even envisage today. But even then, D05’s test methods will be required to support these new technologies and products,” he says.
The committee on coal and coke always welcomes new members to join in the discussion and support the creation and revision of standards. “One of the great things about ASTM is that anyone in the world can join, participate, vote, and be taken seriously,” Reagan says.
Janke agrees. “ASTM brings together everyone from a domestic and international standpoint and makes it work. The political foundations of the members do not matter – whether they vote conservative or liberal, Republican or Democrat. Everyone accepts everyone else on equal footing. Everyone expects and receives the same treatment. That is a fundamental concept of ASTM,” he says.
For information on becoming a member or to learn more about the committee on coal and coke, contact staff manager Melissa Marcinowski at m.marcinowski@astm.org.
July / August 2025
