Material processing with abrasive waterjet (AWS) mainly involves the use of mineral materials such as garnet sand as abrasives. Around 300,000 tons of garnet sand are imported over long distances to Europe every year and are used as a disposable product.
As a result, garnet sand is becoming increasingly rare as a natural resource, a situation that has already led to initial supply bottlenecks and rising market prices. At present, however, there is a lack of equivalent alternatives to garnet sand, on the one hand, and effective processes for recycling the abrasives, on the other. These gaps have been closed by the research project "ReWiProAWS - Resource-efficient and economical production through abrasive waterjet technology."
In the "ReWiProAWS" research project, the project team developed methods and technologies to make more efficient use of materials in the abrasive process. To this end, the team built a system for the reuse of abrasive media and for wastewater treatment. In addition, they investigated alternatives to mineral abrasive media in an elaborate study. The research team concluded that the measures developed in the project could reduce the overall need for imported garnet sand by about 50 percent.
In the first phase of the project, the team drew up a comprehensive list of specifications of alternative blasting abrasives and their possible uses. However, the team did not replace one mineral material with another; rather, the team focused on reducing raw material consumption by using waste products from other industries, such as broken glass, gravel or by-products from metal production, for example.
The team analyzed the wear mechanisms of various abrasives and the factors that influence their performance during component processing. On the basis of these analyses, the researchers defined possible applications of the abrasives. The team also analyzed the properties of numerous materials commonly used in industry, since the material properties significantly influence the processing results as well as the wastewater and treatment products generated. The materials covered in the list of specifications range from different metal alloys to special and composite materials.
In the second phase of the project, the project team dealt with the topic of "closed-loop recycling." On the one hand, the researchers wrote a feasibility study on reusing abrasive media in AWS production, and on the other hand they built two components for a modular treatment system as an add-on for existing waterjet machines.
In the feasibility study, they investigated the extent to which closed-loop recycling can be implemented in AWS production and how economical it currently is. The team was able to demonstrate that it is technically feasible to completely reuse blast media and wastewater in a closed loop. However, the recycling of wastewater in particular is still too costly to be economically viable at present.
As part of the joint project, the team produced a filter system for recycling blasting media and a wastewater treatment system. The filter system efficiently screens used blasting media out of the wastewater and from the wastewater and prepares it for reuse. If, after a few applications, the abrasive is too worn for reuse after a few applications, it is removed from the circuit and can then be can then be used elsewhere, for example as a filler in concrete production. The filter system can be connected with the chemical wastewater treatment system developed as part of the project, which makes it possible to reuse the wastewater.
The team developed the wastewater treatment infrastructure in compliance with the strict EU guidelines on the discharge of wastewater into the sewer system. Both components were successfully tested under industrial conditions at one of the project partners.
The application of the project results, as the project team was able to demonstrate, can significantly reduce resource consumption in practical operation of the waterjet technology. The concept developed in the project can also be transferred to other processes, such as grinding.
The research project was funded by the German Federal Ministry of Education and Research (BMBF) as part of the "KMU-innovativ Produktionsforschung" funding program.