Why measurement technology is becoming a key factor

Europe is pursuing the goal of keeping critical raw materials such as lithium, nickel, and cobalt more strongly within its own economic cycle. These metals are key components of lithium-ion batteries and can be recovered by recycling used batteries. Battery recycling thus completes the transition from small collection boxes to a key task of pan-European industrial policy.

However, whether the targeted recovery rates will be achieved is not decided at the political level, but in the chemical process. Metals must be selectively dissolved, separated with a high degree of purity, and recovered in a reproducible manner. In Europe, the hydrometallurgical route is increasingly establishing itself for this purpose. It allows the targeted processing of black mass from the mechanical pre-treatment of used batteries, which contains the relevant electrode materials with lithium, nickel, cobalt, and manganese.

The focus is on the leaching step. Here, temperature, pH value, concentration, and dosage must be precisely coordinated. Stable and reproducible process control is not possible without powerful measurement technology. This is exactly where Endress+Hauser comes in as a competent and reliable partner.

Focus on hydrometallurgy

Compared to the pyrometallurgical process, in which materials are burned and melted at very high temperatures, hydrometallurgy works in an aqueous phase. The aim is to selectively extract the metals contained in the black mass from the solid matrix and then precipitate them again in high yields, either sorted by type or as a defined mixture. This is also the basis for what is known as pCAM (precursor cathode active material) production, in which a precisely defined metal hydroxide mixture is produced as a precursor for new cathode materials – a trend that promises higher margins for recyclers but is much more demanding in terms of the process, as the metal ratios must be precisely adjusted. The leading process variables remain pH value and temperature – the measurement technology used therefore remains crucial. It is precisely this tension between the desired product and yield that makes the process particularly challenging. The leaching step typically takes place in stirred reactors, where aggressive acids or alkalis come into contact with the black mass. Even slight deviations in pH value and temperature can reduce the yield or impair product quality. In addition, there are mechanical stresses caused by abrasive solids and chemical stresses caused by highly corrosive media. Hydrometallurgical processes are therefore not only chemically complex, but also place high demands on the plant technology used.

Measurement technology as a guarantee for process reliability

Temperature, pressure, and level measurements are used to monitor plant safety. For temperature measurement, solutions that do not require direct contact with the medium are ideal, as they prevent leaks and increase the service life of the sensors. Pressure measuring devices with ceramic measuring membranes withstand chemical and mechanical stress and enable reliable monitoring of pipes and pumps. The combination of continuous level measurement with foam detection and limit switches protects against overflow or dry running situations.

Efficient use of resources for optimal results

Process reliability forms the basis for stable plant operation, but does not guarantee a high recycling rate. pH value and temperature are the leading process variables for yield and quality, but this control only works with precise and reproducible dosing of the chemicals used. Accurate quantity measurement is therefore essential. Magnetic-inductive flowmeters offer decisive advantages here, as they work reliably even with aggressive and solid-laden conductive media. They measure with low wear and virtually no pressure loss and, thanks to a 0 × DN full-bore design, sometimes without a lead-in section, which is particularly important in tight installation conditions. A prerequisite for stable measurement is correctly executed potential equalization, which minimizes interference and ensures signal quality. The function of true ground-free measurement is particularly advantageous. This creates a reliable basis for precise control of chemical addition and thus for consistent process quality with low resource consumption.

A focus on auxiliary circuits and energy efficiency

Hydrometallurgical processes are temperature-controlled and therefore rely on external heating or cooling circuits. Measurement technology has a dual function here. On the one hand, it ensures stable reaction conditions and enables targeted energy management. Continuous recording of the heat quantities transferred makes energy flows transparent and reveals potential for optimization. Comparative measurements before and after the reactor enable efficiency losses or leaks to be detected at an early stage. In addition, conductivity and pH measurements ensure the quality of the heat transfer media used. They help to prevent corrosion or deposits. Precise instrumentation thus contributes not only to process stability, but also to the long-term economic efficiency of the plant.

The closed loop begins in the details

Battery recycling is thus becoming a key element of the European circular economy. The regulatory framework is in place and the technological concepts have been established. At the same time, battery technology is constantly evolving. Manufacturers are working to reduce the use of critical raw materials such as cobalt and to use alternative cathode materials. However, this development does not mean a radical change for recycling. Regardless of the specific cell chemistry, the valuable materials contained in the battery mass must be dissolved, separated, and recovered in a defined quality. The hydrometallurgical process chain therefore remains technologically constant.

What is crucial is not the exact composition of the battery, but the ability to process different input materials in a stable and reproducible manner. This is precisely where the value of precise measurement technology comes into play: the wheel of the circular economy keeps turning, and measurement technology keeps it on track.