Fire & Explosion Risks at Aluminum Plants

After the midnight shift started on September 11, 1967, an explosion rocked Reynolds Metals Aluminum, a casting plant in Muscle Shoals, Alabama. The explosion disintegrated 200 feet of a concrete wall, bent steel beams, and made the ground shudder in neighboring towns up to six miles away. The initial blast killed three workers at once, with a fourth succumbing to his injuries by the next afternoon. More than 40 other workers were also injured.

While molten metal explosions were unfortunately normalized in plants at the time, this was such an extraordinary amount of damage that it caught the entire industry’s attention. It was this catastrophe that led the Aluminum Association and aluminum businesses to their pool resources and investigate how molten metal explosions happen, and how to prevent them.

Although this all happened closer to the heyday of aluminum production in the U.S., and now the majority of aluminum plants are overseas, this is not just a historical or faraway risk. The risk of aluminum plant fires and explosions, while mitigated, is still present in the U.S.

What Aluminum Plants Produce

There are two main types of aluminum production. With primary aluminum plants, you produce ingots or billets of aluminum—basically various sized bricks of the substance. Secondary aluminum comes from recycling cans and scrap metal. The process of recycling scrap metal is far more energy-efficient than primary aluminum production, but it still requires using some primary aluminum. Most aluminum plants in the U.S. are secondary aluminum companies.

Where This Aluminum Is Used

This lightweight metal resists corrosion, conducts heat and electricity well, and can be found in anything from cans, foil, and zippers to cars, airplanes, and spacecraft. Aluminum is also widely used for construction materials and infrastructure, from skyscrapers to home roofing. Whether it’s for washing machines and fridges, or laptops, eyeglasses, solar panel nanotechnology, and even cages that protect divers from Great White sharks, aluminum is depended upon in daily life and in just about any industry you could think of. Not only does aluminum have endless uses, but it can also keep being recycled.

A Brief History of American Aluminum Smelters

Since 1901, aluminum production was prominent in the United States, but it was World War I production that catapulted the U.S. to become one of the highest producers of primary aluminum in the world. At that time, the U.S. produced 53% of the world’s primary aluminum. The industry took a hit in the Great Depression, but even though it was built from 1930 to 1932, the Empire State Building was the first to incorporate vast amounts of aluminum.

By the 1940s, there were 28 aluminum smelters built in the country, and they would go on to produce primary aluminum for up to 50 years. The U.S. primary aluminum industry reached its zenith around 1980, with 4.65 million metric tons produced with 40 active aluminum smelters built.

While the 1990s still saw a lot primary aluminum produced, the country was down to 23 smelters. Between 2000 and 2020, 15 more smelters shut down. In 2021, the U.S. was producing less than 2% of the world’s primary aluminum, and now aluminum equipment and facilities are also aging.

How Many Primary Aluminum Plants Are in the United States?

As of 2023, there were 7 primary aluminum smelters in America, with only 4 of them active, while 1 was partially idled and the other 2 closed down. Not only is the manufacturing equipment dated at these smelters, but so too are the electrical systems and computers running the smelters, as these were built between 1970 and 1980. The newest construction was the Mount Holly smelter, built in 1985.

The company Alcoa has 4 of the 7 aluminum smelters:

• Massena Operations in Massena, NY: Built in 1902, it is the oldest continuously running in the entire world and can still produce 130,000 metric tons a year.
• Warrick Operations in Evansville, IN: This smelter could produce 269,000 metric tons per year, but it is partially idled.
• Intalco in Ferndale, WA: This one has an even higher production capacity but was permanently closed in 2023.
• Wenatchee, WA: The smelter here idled in 2015 before being closed for good in 2021.

Century Aluminum has 3 of the other aluminum smelters:

• Sebree, KY: Has a capacity to produce 220,000 metric tons of primary aluminum.
• Mount Holly, SC: Could produce 230,000 metric tons, but is partially idled.
• Hawesville, KY: Could produce 250,000 metric tons a year but is idled as of 2022.

Finally, there used to be one more primary aluminum smelter. Magnitude 7 Metals had a smelter in New Madrid, MO that was closed permanently in January 2024, after the electrical gear switch failed.

Secondary Aluminum Production Plants in the U.S.

While primary aluminum plants barely exist in the U.S., secondary aluminum plants have been cropping up in higher numbers. Back in 1973, 1 million metric tons of secondary aluminum were being produced, while by 2021, production was up to 3.3 million metric tons. In 2020, there were 113 active secondary aluminum facilities.

According to sources cited by the Aluminum Association, there are about 164,000 workers in the aluminum industry in total, with 535,000 workers classified as working in indirect support of this industry.

What Is the Aluminum Association?

Established in 1933, the Aluminum Association is a trade association in Arlington, Virginia that tracks and collects key information on the aluminum industry and reports on best practices. The group also advocates for the aluminum industry, for U.S. jobs in the industry, and for investment in aluminum because it is a sustainable metal to produce and recycle. Since the Aluminum Association collects data and studies from a wide range of sources, it provides a near-comprehensive record on many issues that affect the aluminum industry.

What Are the Fire Risks of Working with Aluminum?

Working with molten aluminum means working with metal that can get as hot as 1,300 to 1,450 degrees Fahrenheit, which brings the risk of burn injuries and fire hazards. But for the most part, pure aluminum is not particularly combustible. It’s one of the characteristics that makes aluminum highly valuable. By the definitions set out by the National Fire Protection Association (NFPA) and through tests run by the Aluminum Association, “solid bulk aluminum does not burn” when exposed to oxygen or under the normal conditions found in construction and industrial settings.

Aluminum powder, however, is a different story. Pure aluminum powder will not burn, but aluminum powder can quickly rust or ignite when it is an alloy, that is, when it is mixed with other metals.

For instance, aluminum powder that’s mixed with rust or steel can burn. When a rusty nail is hammered into uncoated aluminum, this strike can create particles that combust. While the nail and aluminum itself won’t catch fire, because anything nearby can ignite, this simple act can start a fire. That is why exposed aluminum needs to be painted. If rusty steel or any other rust interacts with aluminum, the fire risk is eliminated by an intervening layer of paint.

What Are the Explosion Risks at Aluminum Plants?

Because they’re practically weightless, aluminum powder particles can spread out and hang in the air. While any one of these particles can present a fire risk, when fine aluminum powder creates even a small dust cloud, one particle catching fire can set off a near-instantaneous chain reaction. That’s what happens in slow motion. In real time, this looks like a sudden explosion.

For one of these particles to catch fire, the only ignition source needed is static electricity or a spark. This spark can be set off by metal-to-metal impact, or even through friction, broken light bulbs, or loose electric power connections, etc.

Sources of Aluminum Powder Dispersion & Ignition

Grinding, sawing, cutting, sanding, and scratch brushes are just some of the processes and tools that can not only create aluminum powder, but can also create sparks that set them off.

When aluminum dust is created, it can also catch fire in the presence of:

• Open flames
• Welding torches, cutting torches, or blowtorches
• Matches
• Cigarettes
• Static electricity
• Any spark at all

If there are enough particles in the air, along with some oxygen or other rust-causing agent, this ignition can turn into a full-blown dust explosion.

This is what dust collection systems must prevent, ensuring that fine dust doesn’t build up, but instead flows into a collector. Every aspect of these systems, from ducts and hoods to enclosures and collectors, needs to not oxidize (be rustproof) and be made of a metal that can’t create sparks. And it’s a system that cannot be used to collect any other types of dust or metals—that would be disastrous, potentially explosive. Each metal needs its own collection system. It must also prevent static electricity, so the aluminum dust collection system needs to be grounded.

Dust collectors should be emptied every day, or even more often if significant dust builds up (or in wet systems that use collector liquid, to ensure it doesn’t turn into a growing sludge). This disposal has to be handled oh so carefully to keep dust clouds from cropping up and then stored in well-sealed containers thereafter.

The aluminum dust collection and vent systems should be repaired as needed, but before such work is conducted, the system needs to be emptied and cleaned by trained, qualified personnel, who will also need to cap off the ducts.

The Many Potential Pitfalls of Working with Aluminum Powder

Static and sparks need to be avoided at all costs. Aluminum powders must also be kept away from paper, oily rags, or anything else combustible. Even cleaning up aluminum powder can be hazardous. It takes natural bristle brushes and squeegees to safely clean walls and other surfaces. Synthetic or plastic brushes could create disastrous friction and static. Avoiding friction also means avoiding processes that involve metal-to-metal or metal-and-concrete interactions, so no dropping a steel tool onto a concrete floor, or no using an aluminum tool on a rusty nail. Tools and processes around aluminum powder must be planned out very carefully.

For bigger cleanups, normal industrial vacuums can’t be used either. You need very specific, certified for Group E combustible dust vacuum systems that can be used for cleaning under very specific circumstances.

Transferring aluminum powder can be a tricky business as well. It needs to be done with a conductive metal scoop that can’t spark, and it must be done slowly, disturbing the powder as little as possible so it doesn’t spray up into the air.

When it comes to mixing processes with aluminum powder, the equipment needs to have a tumbling action instead of moving parts, as something like a blender can create heat from friction. Sometimes handling under inert, or nonreactive, gas, like helium, can mitigate the danger, such as by keeping any tumbling motion from churning up aluminum powder dust clouds. Pouring powder cannot be done on a nonconductive surface either, as this can create static.

Aluminum Powder & Paste Storage

Aluminum powder (and aluminum paste, that is, aluminum flakes in a solvent) needs to be handled, stored, and shipped safely, as it’s being maintained and transported in the form that poses the highest first and explosion risks.

Aluminum powders and water also cannot mix—one of the things that makes fighting any such fires extremely difficult. So not only does work with aluminum need to be done far away from any steam lines, water lines, and leaky radiators or roofs, but aluminum powder should not be stored near any steam pipes, radiators, or heat sources. And of course, containers of this powder need to be properly sealed in a dry room that won’t heat up.

How Do You Fight Aluminum Powder Fires?

Aluminum powder fires are exceptionally difficult to control, beyond the normal scope that even highly trained firefighters might be expected to face. Aluminum plants need to employ a firefighting officer or safety officer who can superintend firefighting efforts.

If the fire breaks out over a flat surface, it’s possible to try containing it with dams of dry sand, and/or you can try to smother the fire with Class D dry extinguishing agents. Either method has to be carried out carefully, since if anything moves the burning aluminum powder, it can send it up in puffs, and any dust clouds created can then explode. The extinguishing agents must be scooped or shoveled with non-sparking, long-handled shovels or similar tools. As for water, spraying it onto aluminum powder can send up more hot particles into the air, leading to explosions.

Whether dammed up by sand or covered up with extinguishing agents, an aluminum fire can then burn itself out. As the controlling and extinguishing measures are being applied, it’s vital to ensure that dust collection systems, fans, and other machines are turned off. Once done with firefighting measures, the doors need to be closed and sealed with sand.

Minimizing Fire & Explosion Risks at Aluminum Plants

Aluminum plants need to have proper procedures and safety gear in place, but if they don’t provide proper and repeated training, avoidable disasters can ensue. For instance, in the face of a fire, it would be someone’s instinct to fight the fire with water, or to grab a standard fire extinguisher. But that would spread and exacerbate the fire. It would take adequate equipment and training to ensure that workers have both the insight and tools they need to react quickly and correctly to a fire.

Workers also need to be supplied with personal protective equipment (PPE) to keep them safe from burn injuries.

This would include gear such as:

• Eye and face protection
• Gloves
• Fire-resistant or fire-retardant fabric for protective clothes that won’t build static electricity
• Keeping pants uncuffed (dust can collect in the fold)
• Shoes that don’t let static build up

Of course, personal gear and training aren’t enough on their own; aluminum facilities also need enough fine dry sand and the right extinguishing agents on hand for workers, along with the appropriate tools to apply those extinguishing efforts.

Accidents at Aluminum Plants: The Data

The following data depends on self-reporting, so this is an incomplete picture of the types of accidents that occur at aluminum plants. But it still provides a wider view than the individual incidents detailed later.

That said, the Aluminum Association collected these self-reports from around the world and has done so for decades. Looking at reports from 1981 to 2023, the highest number of molten metal incidents occurred in 2022, at 198 explosions. In 2023, there were 156 reported aluminum explosions.

According to the Aluminum Association’s terms, those 2023 numbers break down to:

• 130 Force 1 explosions
• 25 Force 2 explosions
• 0 Force 3 explosions

What are these Force numbers? A Force 1 molten metal explosion doesn’t damage property, doesn’t give off much light, will give off a short cracking sound and vibration, and won’t send metal flying very far. A Force 2 explosions does damage property, gives off a flash and loud sound, and even makes the ground roll from the impact. Metal can be flung as far away as 50 feet. Force 3 explosions create intense light, painful sounds, and “massive structural” vibration that leads to “considerable” property damage.

While the number of overall explosions was highest in 2022, the number of Force 3 explosions has dropped, as has the number for Force 2 explosions. No fatalities were reported for these types of explosions in 2023. There were 17 injuries reported along with these 2023 incidents, with one being recorded as a serious injury.

Since 1981, these self-reports recorded:

• An overall number of 99 fatalities from molten metal incidents
• A total of 1,645 injuries from these explosions
• The highest number of minor injuries in 2007, at over 90 injuries
• The highest number of serious injuries in 1986, at approximately 38
• The highest number of fatal injuries in 2007 as well, at 19

Causes of Molten Metal Accidents/Explosions

Based on the 2022 and 2023 numbers, aluminum casting and transfer that involved wet or rusty drain pains was the cause behind 20% of these explosions. Casting involves pouring molten aluminum into a cast where it will cool and take shape.

In 62 of the explosions that occurred during casting, equipment failures, power loss, wet hand tools, and improperly heated or cracked molds were also to blame. In 42 of the transfer explosions, wet tools and issues related to metal on the floor were faulted.

In 2023, there were also 42 explosions during melting, and a significant percentage of these were blamed on the scrap metal being wet or contaminated.

This bears out over earlier decades of statistics as well, the high percentage of explosions taking place during aluminum casting and transfer. The causes of these explosions were often the same as they were in more recent years too.

Accidents at Aluminum Plants: Specific Instances

While we’ve looked at a global snapshot of some aluminum plant accident numbers, by looking at some specific incidents, we can get a better idea of what aluminum workers in the U.S. are facing decades after the Reynolds Metals Aluminum explosion.

Some recent aluminum plant accidents include:

• November 2, 2017: At The Top Die Casting Company in South Beloit, IL, a worker was transferring aluminum metal scraps to a furnace for remolding. He was using a forklift without a shield, and as he was loading and pushing about 25 cold aluminum ingots into a furnace, there was an explosion. This sprayed molten aluminum from the furnace onto the man’s arms, torso, and head, sending him to the hospital with second- and third-degree burns. The manufacturing plant was cited and fined for not providing adequate training to the worker on procedures and use of PPE.
• November 13, 2019: At B-N Enterprises Inc at Russellville, KY, an employee was using a forklift to hoist a 48-ton aluminum ingot onto a trailer when the ingot slipped, struck the employee, and killed him.
• September 13, 2020: A group of workers had finished pouring aluminum into a cast at Logan Aluminum in Russellville, KY. As they were cleaning the casting trough ahead of another pour, the trough was still hooked to a crane. When one employee moved the crane, this yanked at the trough, striking two workers with it. One worker was hit onto the casting table, but the other was tragically sent into a casting pit with molten aluminum. The employee’s left leg and backside contacted the molten metal, and his clothes caught on fire. While he was able to get out of the pit, and his coworkers extinguished the fire, the man had to be rushed to the hospital with third-degree burns. A month later, during physical therapy at the hospital, the man had an embolism and died. The company was cited for serious violations and fined just $11,200.
• September 12, 2024: Zarbana Aluminum Extrusions in Columbiana County, OH experienced what was initially reported as an explosion, but was later determined to be a steam flash incident that hospitalized three workers. While aluminum billets were being poured, molten aluminum that was about 800 degrees Fahrenheit, it flowed over the rim of the container, coating one worker in molten metal who had to be airlifted to treatment. Both the pallets and other flammable items caught fire in the incident, and while firefighters were able to put the fire out, two other workers had to be rushed to the hospital with burn injuries.

While there are industry-specific hazards for aluminum workers, workers in any industrial setting can face struck-by accidents, falling object risks, or falls from heights. Whether it’s due to the heightened fire and explosion risks found at aluminum plants, or it’s a more common type of workplace accident, the responsibility to mitigate these risks always falls on the employer. When tragedy does strike, that means an employer wasn’t doing what they needed to protect their employees.

Aluminum Companies Are Responsible for Worker Safety

According to the Aluminum Association, the decreasing injury rate over the years can be taken as a sign of improvements in PPE, its usage, materials and design, as well as in advanced tools that allow for hands-free casting. Improvements that keep people away from risky areas have proven effective, and the promising trend could also speak to enhanced awareness and training measures.

That means that the aluminum industry knows what works. It’s not possible to blame ignorance or lack of data for plant accidents, fires, or explosions at aluminum plants. It’s up to companies to make sure that everything is up to code and in good repair at their facilities, and that workers are thoroughly trained in best practices and equipped with safety gear.

If machines fail, processes go awry, or other issues cause injury or death, then that incident occurred due to something that was preventable. That means an employer along the way failed to provide the inspections, repairs, or training needed, or they failed in some other duty. Workers deserve better than that. Their loved ones deserve better. If someone gets hurt or loses a loved one because of such an accident at an aluminum plant, they deserve to get answers and to hold those negligent companies accountable.