Progressing, scarcity of resources and increasing prices of raw materials as well as now often prohibited landfilling of hazardous wastes increase the demand for recycling techniques for the residues of the iron and steel industry. A by-product of the steelmaking process is steel-mill dust, which is produced in a non-negligible amount during the process. These dusts contain iron, zinc and more valuable metals. A few decades ago it was common practice worldwide to dispose the dusts in landfills, which meant a major loss of reusable material in the material cycle. By now rising costs for raw materials and more severe restrictions in laws concerning waste disposal in the European region have led to a nearly complete recycling of the produced dusts in different recycling processes. Within the last decades there have been several process developments. Few of them have made it to a large scale commercial application in the recycling industry. The RecoDust-Process with the Flash-Reactor plant is a new process that is so far in pilot plant application at the Chair of Thermal Processing Technology at the Montanuniversität. In a single-step process the steel-mill dusts are molten in a reducing natural gas/oxygen flame at temperatures up to 1800°C. The less volatile components accumulate in a liquid slag at the bottom of the reaction vessel, while the volatile components are separated with the flue gas, enter post combustion and are separated from the gas flow in baghouse filters. This leads to a separation and accumulation of the different fractions. The declared aim is the production of a saleable zinc oxide and an iron containing slag that fits as iron carrier in the steelmaking process. This treatise shows a detailed pilot plant description as well as the results of the first test campaigns. In addition it contains the resulting reconstruction and improvement measures at the pilot plant.