What was once considered a worthless byproduct is now used to color paving stones, concrete, and buildings all over the world. For 100 years, iron oxide pigments have been produced at the LAUX plant in Krefeld-Uerdingen using a process that is unique worldwide. This is a story about chemistry, the circular economy, and a highly interconnected production network where scrap iron, experience, and teamwork come together to create world-class pigments.

During our visit, plant manager Holger Friedrich drinks his coffee from a mug featuring the periodic table of elements. This is a small detail that says a lot. Because when the manager of the reduction plant talks about the LAUX process, it certainly doesn’t sound like business as usual.

The fact that the facility is still referred to as a reduction plant has historical reasons. “Actually, we produce iron oxide pigments in other words, we oxidize iron,” explains Friedrich.

“The name comes from the fact that, through this oxidation, we simultaneously reduce nitrobenzene to aniline.” Because in the beginning, the focus wasn’t on the pigment at all. When the process was developed in the early 20th century, aniline – which was needed to produce synthetic dyes – was considered a valuable substance. The iron oxide accumulated as sludge, and for a long time no one knew what to do with it. It wasn’t until the mid-1920s that chemist Julius Laux recognized the potential of this byproduct, thereby laying the foundation for industrial iron oxide production.

The most important raw material for a reduction plant comes from the automotive industry – which, at first glance, has little to do with pigments. Iron shavings and metal scrap generated during the machining of castings are used. “So we were already committed to the circular economy even before the term officially existed,” says Christian Schütte, who has worked at the company for more than three decades and is in charge of raw materials procurement. "Sustainability has always been an integral part of our process."
 
However, not all waste is the same: “The quality of the iron we receive clearly plays a key role in determining the quality of the pigment,” explains the expert. In a huge warehouse, varieties with different grain sizes and qualities are therefore mixed together to produce the best possible raw material. The material is then mechanically processed in the grinding mills, graded, and prepared for the production process. In the reduction plant, the actual reaction then proceeds almost entirely automatically. This reaction is highly exothermic – meaning it releases large amounts of heat. This energy is put to good use: to generate steam and hot water for the plant’s own processes, as well as for other plants on the site. “In a sense, we’re IPG’s boiler room,” says Schütte.

From a Liquid Substance to a Solid Pigment

At the end of the process, the iron oxide leaves the reduction plant as an aniline-free paste – thick and completely free of any harmful substances. It is then transported via pipe bridges to the next facility: pastes and calcination. “This is where the product takes shape,” says plant manager Bartholomäus Luczak. “We turn the sludgy mass into a solid material.”

In terms of area, pastes and calcination is the largest facility in the Chempark: six large main buildings, five control rooms, and an extensive network of pipelines covering an area of about 5 hectares. Here, the thick paste is cleaned of iron residues, thickened, washed, and then dried. Then the next step depends on the color: Black or yellow pigments are produced directly from the process. To produce the red pigments, the black paste is then calcined – in other words, heat-treated.

This process takes place in the massive rotary kilns located in a separate section of the building, where temperatures reach up to 900 degrees Celsius. Regina Müller, assistant shift supervisor, is currently making her rounds there. It’s not just the scale that’s impressive – the entire atmosphere is striking as well. Over the years, the massive furnaces, pipes, and equipment have taken on the red color of the pigment calcined here. “It’s usually much warmer here,” she explains. “But our kilns are currently being serviced.”

Maintenance is generally an important issue for the Uerdingen team. The pigment is highly abrasive – screw conveyors, pipes, and equipment are subjected to enormous levels of stress during continuous operation. Equipment must therefore be inspected, serviced, and maintained on a regular basis. “Despite automation, you spend a lot of time moving around the plant, switching lines, and sometimes intervening manually,” says Müller. “That’s what makes the job so interesting to me.” 

It goes without saying that the pigments don’t just color the hall and its surroundings – by the end of their shift, workers’ clothes bear visible traces of the product.

A Strong Whole – for 100 Years

After passing through the paste and calcination stages, the pigment’s journey still isn’t over. “We hand it off to our colleagues in the grinding department,” explains Müller. Here, the pigment undergoes further processing – it is mixed and either finely ground for its intended application or compacted into a low-dust form, depending on how and for what purpose it will later be used by the customer.

The closely integrated production network is one of the reasons why the process remains successful even after 100 years – and why it isn’t used anywhere else in the world. "Many process steps, long distances, large quantities. Material flows must be coordinated, and turnaround times must be met – around the clock.

This team spirit, combined with 100 years of experience, isn’t something you can just copy.