Pyrometric temperature and size measurements of chalcopyrite particles during flash oxidation in a laminar flow reactor
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I. INTRODUCTION
THE Outokumpu flash smelting process, adopted in industrial use in 1949, is nowadays a state-of-art method for primary copper production. Since its invention, flash smelting has been continuously developed in order to improve its efficiency and to reduce its environmental impacts. To assist in this development, chemical and physical models have been developed aiming at describing various processes occurring inside the smelter. For the reaction shaft, there are dedicated models for chemical reactions[1] and radiative heat transfer.[2] However, there is a lack of experimental data, which are needed as an input for the numerical models and, in particular, for the validation of the models. Such a parameter is, for instance, the temperature of reacting particles. There are only a few reports available in the literature on particle temperatures in the flash smelting process[3,4,5] and no reports on simultaneous measurement of particle temperature and size. There is a great variety of modifications of optical pyrometry for the nonintrusive measurement of the temperature of individual fuel particles in combustion.[3–17] Some of these works also report on simultaneous size measurement of individual fuel particles.[6,9–12,14] Two-color pyrometry has been the most common method for the measurement of the temperature of individual particles in flow reactors.[1–10,12–15] The major advantage of this method is its independence not only of the size but also of the emissivity of the particle. However, the true temperature is obtained only for gray bodies, i.e., particles hav-
ing equal emissivity at the two wavelength bands of the pyrometric measurement. For nongray bodies, a systematic error occurs, which depends on how much the ratio of the emissivities at the two wavelength bands deviates from unity. The objective of the present work was to develop a fast and sensitive two-color pyrometer for the simultaneous measurement of temperature and size of individual chalcopyrite (CuFeS2) particles in the size range 20 to 200 m and temperature range 1300 to 2600 K, moving at velocities 0.5 to 3 m/s in an electrically heated laboratory scale laminar flow reactor. The instrument uses a particle pyrometric method that has been previously applied to the size and temperature measurement of fuel particles in a variety of combustion reactors.[19] A faster modified pyrometric instrument with a 10 s response time has been used in fuel particle thermometry in pulverized combustion.[20] Most commercially available nonimaging pyrometric instruments have substantially larger response times.[20] In the present work, the fast two-color pyrometer was further developed and applied to the measurement of individual chalcopyrite particle temperatures and sizes in the laminar flow reactor, which was used to simulate the reaction shaft conditions in an industrial scale flash smelter. Measurements were made at different oxygen levels, gas temperatures, and reaction distances using two particle size fractions. II. EXPERIMENTAL A. Two-Color O
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