In this work, kinetic runs of self-reducing mixtures composed by pellet feed, BOF dust and biomass of elephant grass were performed using TGA-DSC method, for the temperatures, 900, 950, 1000, 1050 and 1100°C, and carbon percentages (15, 20 and 30% of carbon). The converted fraction versus time was calculated, and the different regions of the reactions progress were selected to analyze the reactions kinetics that occur in the mixture (devolatilization of biomass, Boudouard and sequence of reduction reactions). The kinetic behavior for the different steps showed good agreement with the first-order kinetic law. Using Arrhenius plot, was possible to estimate the apparent activation energy values obtained for the reaction mechanisms corresponding to Fe3O4→FeO and FeO→Fe. The kinetic constants for the 1100°C temperature and mixture containing 30% of carbon were the higher values: 0.0037 s-1 for the reaction Fe3O4 → FeO and 0.0258 s-1 for the mechanism FeO →Fe.

No abstract

The present study is primarily engaged in the implementation of the incremental stamping process in a computerized numeric control This paper presents two different approaches to this forming process, an experimental and other numerical. Experimental used by the computer numerical control to perform the printing process and performs numerical simulations of the process using the finite element method. Some parameters are analyzed in both approaches, such as product geometry effects, tool geometry, tool speed, tool path, contact conditions and mechanical properties of the materials.

The increasing demand for new technologies in the ironmaking/steelmaking field has been motivating several studies towards pelletizing process improvement. Within this context, evaluate the reduction of iron ore pellets using the dilatometer technique constitutes a promising approach for optimizing this process. This paper aims the metallurgical characterization through the sintering of particles in iron ore pellets. With this purpose, some experimental procedures are of concern as follows. Firstly, the kinetic densification of the iron ore pellets is measured using a dilatometer, which heats the samples up at 30 K/min until high temperatures about 1473 K and an isotherm at 10 minutes have been done. Then, the sample is cooled back to room temperature and undergoes a microstructural characterization, with the aid of a scanning electron microscope. At last, the density of the pellets is evaluated, using an Arquimedes Principle and consequently the porosity of the agglomerates. The results indicate the sintering progress of the particles that comprise the pellets as well as reduction the porosity. This behavior is due to the fact that the heat arising from gas induces the partial liquid phase formation and involves the agglomerate particles aiding in the sintering process.

No abstract