When dismantling large radioactive steel components, the water jet abrasive suspension cutting process (WAS) offers many advantages compared to other dismantling processes. During the cutting process, a mixture of abrasive particles and radioactive steel particles is produced from the dismantled component, which must be disposed of as additional radioactive waste. When using the WAS process, the amount of radioactive waste increases considerably. In order to reduce the amount of additional radioactive waste, a separation process based on sieving and magnetic filtration was developed to obtain a fraction of the mixture that can be reused for the next WAS cut. The direct reuse of the separated abrasive means that less new abrasive is required and therefore the amount of secondary waste is reduced. A separation plant in batch operation was developed to assess the separation process. The testing phase showed an adequate separation grade and high potential for reduction of additional radioactive waste. A transfer from batch operation to continuous operation will be essential for future utilization and to upscale the processing of the particle mixture. In this regard, a concept for the continuous operation for a separation plant as well as a closed, continuously operating sieve and magnetic filter have been developed. This article presents a newly developed, closed and continuously operating magnetic filter and its initial results. This magnetic filter was designed as part of a separation system aimed at reducing additional radioactive waste during the dismantling of nuclear facilities.