This paper deals with electric arc furnace off-gas heat recovery and first experiences with a testing plant. The testing plant based on molten salt as heat transfer fluid was installed inside the existing off-gas system of a German mini mill. Targets of the testing plant are to evaluate tube materials and to measure the influence of hot corrosion and dust settlement. First experimental results are presented. Besides experimental measurements numerical simulations were performed. A process simulation was necessary to describe process dynamics. A computational fluid dynamic simulation of the testing heat exchanger was done to calculate the off-gas flow profile around the heat exchanger.