Lubricant in recycling lifts CO₂ balance

Lubricant production is energy-intensive. A lot of energy is required from the refined crude oil to the finished lubricant. Accordingly, the_{carbon footprint} of engine and hydraulic oil, concrete release agents, cutting and grinding oil is not exactly rosy. For years, the lubricant specialist Zeller+Gmelin has therefore been making intensive efforts to improve its_{CO2 footprint}: A current example is the production of_{CO2-optimized} industrial lubricants through recycling.

Environmental and sustainability issues have long been a priority for Zeller Gmelin. Even though this may not always seem easy for a chemical company, constant effort pays off. For many years now, the company has been continuously developing new lubricant products—such as concrete release agents, chainsaw oils, and lawnmower oils—based on renewable raw materials. The lubricant manufacturer’s product portfolio in the automotive sector also includes environmentally friendly bio-hydraulic oils, which have been awarded the Blue Angel and the EU Ecolabel.

Recycling with tradition

Yet the concept of recycling is by no means new to this long-established Swabian company; its roots date back to 1935: For nearly 90 years, the subsidiary Südöl has been collecting and recycling lubricants and industrial cleaners. Among other things, Südöl recycles used machine and motor oils and processes them into new base oils and fuels. Reprocessing base oils and returning them to the recycling cycle as fresh oils not only conserves resources but also consumes less energy: The_{carbon footprint} of recycled oil is significantly lower than that of producing fresh oil.

From soft fission to the use of biogenic raw materials

“We rely on three processes for recycling industrial lubricants,” says Jürgen Wranik, head of the laboratory department at Zeller Gmelin. “First, the so-called ‘gentle cracking’; second, recycling through refining; and finally, the development of new products from biogenic raw materials. “We’ve been using the latter for several years now in the development of lubricants for the agricultural and forestry sectors,” says Jürgen Wranik. So what applies to the environmentally friendly, water-based Divinol chainsaw and lawnmower oils is now also being implemented in lubricants for metalworking: the use of biogenic raw materials in the development of new cooling lubricants, grinding oils, and wire-drawing agents. The “gentle separation” of used oils separates the oil and water phases, removes deposits through filtration, and purifies the oil. Through the refining process, used oil is refined into a secondary raffinate, resulting—according to Zeller Gmelin—in a base oil that is virtually waste-free.

Used Oil as a Valuable Raw Material

Industrial companies are required to dispose of their waste or used oil properly, and that costs money. Even though the trend in metal cutting is moving toward minimum quantity lubrication (MQL), vast amounts of used lubricants are still generated. By returning these materials to the recycling cycle, companies can not only save immense costs but also conserve resources and protect the environment. During machining, grinding, or forming, large quantities of high-quality, non-water-miscible oil are typically carried away. In machining, the lubricant ends up in the waste container along with the chips, for example via a chip conveyor. The waste container is then sent to a waste management company, which separates the metal chips from the lubricants. The metal is recycled as a raw material, but the lubricants usually are not. The situation is similar with other machining processes, such as deep drawing of sheet metal. In these cases, the drawing agents used—for example, during cleaning in the parts washing system—are carried away with the waste. Industrial companies had to dispose of this mixture of drawing agents, parts cleaners, water, surfactants, and solid particles at great expense. Jürgen Wranik, Head of R&D for Lubricants: “This is exactly where our concept comes in. For us, the used oil from metalworking is a valuable raw material that we are happy to take back and return to reuse.” This improves both the waste balance and the carbon footprint of metalworking companies. When using virgin oil in lubricant production, rising base oil prices have a significant impact on costs, which is not the case when reusing the company’s own recycled material. According to Zeller Gmelin, cost savings of 30–50 percent can be achieved by using recycled oil instead of virgin oil in lubricants. The lubricant manufacturer’s testing laboratory in Eislingen ensures consistently high quality of the process oil in circulation.