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Full-scale measurements on a mineral melting cupola furnace for stone wool production have been made to investigate the behavior and increase the understanding of mineral melting cupolas. The work includes probe measurements of gas concentration, solid/melt phase and gas temperature, and melt composition at several vertical and radial positions in the cupola. Four types of experiments were conducted:  quenching of an operating cupola, sample collection from the hot part of the cupola using probes through the walls, sample collection through a probe inserted from the top of the cupola, and collection of input and output data. The experiments showed the position of the melting zone, porosity, and other characteristics. The probe experiments indicate that the oxygen is consumed approximately 0.3 m above the tuyeres. The top probe experiments gave the temperature profile in the cupola.

A mathematical model of a mineral melting cupola furnace for stone wool production has been developed for improving cupola operation. The 1-D, first-engineering-principles model includes mass and heat balances for the gas phase, five solid phases, and four liquid phases. The gas and solid/liquid phases flow countercurrently. Seven chemical reactions account for the conversions of coke, iron oxide, limestone, and gaseous species. The heterogeneous reactions of coke conversion are limited by both kinetics and mass transport. Heat transfer between phases is modeled including both convection and radiation. The model predicts gas concentrations; mass flow rates; and temperature profiles of the solid, melt, and gas in the cupola, as well as heat loss to the water-cooled walls. Inputs to the model include the coke, rock, and blast air properties, the blast air amount, and the coke percentage in the charge. The unknown model parameters are estimated on the basis of input/output measurements. A comparison of the predicted and measured concentration and temperature profiles inside the cupola shows good agreement.

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