When I think of aluminum, I picture chutney sandwiches wrapped in a delightfully crunchy silver foil that came with the added benefit of being squishable into balls that made recess more fun. Or, I hear the pop of soda cans opening before a big game and the clink of a spoon against a thermos while camping. What doesn’t come to mind at all are the vast, rust-colored lakes of industrial waste left behind during our utilitarian friend’s production, a substance known as red mud. 

Over the summer, Jacob Hillemann ’26 set out to figure out just how much of this red mud is produced in the United States each year. The answer, it turns out, isn’t readily available anywhere: not in government databases, academic papers or even industry reports.

Working with Associate Professor Jonathan Crones (ENGR) in the engineering program, Hillemann spent the summer researching red mud, which is scientifically known as bauxite residue. His goal was to build a reliable model that could estimate the actual scale of red-mud generation in the U.S., a number that has never been publicly or consistently tracked.

At its core, the research was motivated by a simple question: How much waste are we generating in order to produce our aluminum? To answer it, Hillemann first had to understand the industrial process behind aluminum production, which involves converting bauxite ore into a chemical compound of aluminum and oxygen called alumina, and then refining alumina into aluminum metal. The transformation from bauxite ore to alumina, known as the Bayer process, is what generates waste. The process, very generally, works by dissolving bauxite in sodium hydroxide under high heat and pressure. The goal is to separate aluminum from the rest of the ore. That “rest” is what becomes red mud.

The red color comes from iron oxides, a fancy way to describe what is essentially rust, which form a major component of the leftovers. Beyond making Earth resemble Mars, the red mud can be hazardous. It can be extremely basic, which means it can corrode materials and pose risks to soil, water and people if not properly stored. 

In the U.S. and globally, that waste isn’t always well-contained. In 2010, a red mud storage facility in Hungary burst, flooding nearby communities and killing 10 people. In the U.S., red mud is stored in large surface impoundments, essentially manmade lakes, where it sits for long periods of time until the land is remediated. In 2024, a worker at the alumina plant in Gramercy, Louisiana fell into an uncovered hole and died of chemical and thermal burns. 

Despite all this, there has never been consistent accounting of how much red mud the U.S. produces. Industry reports tend to give numbers in “wet tons,” which include the water content of the mud, a variable factor, since red mud is often between 20-40% solid. That means two “wet tons” of mud could contain very different amounts of actual waste material. 

“They report it in wet tons, which is an arbitrary unit that doesn’t really mean anything,” Hillemann explained in an Aug. 28 interview with The Justice. “The industry reporting is very unreliable and very inconsistent.”

To create a better picture of just how much waste is produced in the country, Hillemann built a computational model from the ground up. He began by digging into data from the U.S. Geological Survey which has kept records of bauxite imports, exports and consumption going back to the 1930s. Since the U.S. no longer mines its own metallurgical-grade bauxite and instead imports all of it from Jamaica, Hillemann used published chemical analyses of Jamaican bauxite to estimate its constituents.

From there, he used published literature reviews to model what happens when bauxite goes through the Bayer process. This highlights which compounds remain inert, which react and what kinds of side reactions might occur that increase the mass of waste. Using this, he created a set of hypothetical reactions to stand in for the kinds of chemical transformations that happen in real-life production.

Eventually, this resulted in a model that could convert raw bauxite consumption figures into an estimate of red mud production in terms of dry weight. Dry weight measures the solid weight of red mud. However, the mud itself is only between 20-40% solid, according to Hillemann, so his findings are below the industry-reported wet ton values. The alumina industry claims to be moving towards dry stacking the waste — drying the red mud before putting it into the surface impoundments — which would increase the solids content, although Hillemann says that industry reported values are inconsistent with a move to dry-stacking.

According to his preliminary findings, the U.S. produced approximately 600,000 dry tons of red mud in 2024 alone. In comparison, the reported number for the 2023-24 year in wet tons was roughly 2,944,205. When an assumption of 20% solid content is made, these values are comparable. 

That number might come as a shock given that only one alumina refinery is currently operational in the U.S., located in Louisiana. But, historically, the U.S. was a major player in aluminum production with up to nine plants in operation at its peak in the 1970s. Even today, that single plant still generates significant waste and it’s not entirely clear how closely it’s monitored. 

“No one is checking these documents that [the plant] is giving to the Louisiana Department of Environmental Quality,” Hillemann said. “No one knows that these values are pretty likely to be inaccurate.”

In addition to estimating the volume of red mud, Hillemann’s research also touched on what might be inside the waste. While the focus of his project was on quantity, not content, he noted that red mud contains trace amounts of metals like titanium, iron and gallium, some of which have economic value. Gallium, for instance, is used in electronics and semiconductors, and red mud is already a primary source of it worldwide. 

“There are valuable materials in the red mud,” he said. “There’s research going into getting those out of the red mud in an economically viable way.”

Still, recovering these elements isn’t easy. The concentrations are low, and separating them efficiently remains a challenge that most countries, including the U.S., haven’t solved. For now, red mud remains mostly a waste product with no end use in sight.

The aluminum we use every day might seem lightweight and recyclable, and in many ways, it is. But the story of how it gets to us is anything but clean.  Next time you think about tossing that aluminum foil ball at a friend, consider unwrapping and reusing.