Caracterización química, mineralógica y térmica de boratos naturales y sintéticos

Abstract

En este trabajo se ha establecido una metodología para caracterizar boratos naturales y sintéticos utilizados como materia prima en la industria cerámica, ya que no se ha encontrado en la bibliografía información detallada al respecto. Se han analizado cuatro boratos naturales, tres colemanitas de diferente riqueza y una ulexita, así como dos boratos sintéticos, un ácido bórico y un bórax pentahidratado. Las técnicas analíticas utilizadas para la caracterización han sido: espectrometría de fluorescencia de rayos X (FRX), espectrometría de emisión atómica de plama acoplado inductivamentes (ICP-OES), potenciometría, difracción de rayos X (DRX), termogravimetría (TG) y análisis térmico diferencial (ATD). En la caracterización química se han analizado los elementos Si, Al, Fe, Ca, Mg, Na, K, Ti, Sr, As y S mediante FRX y los elementos B y F se han analizado por varios métodos y se han comparado los resultados obtenidos. En la caracterización mineralógica, se han determinado los minerales de boro y otros minerales presentes que acompañan a éstos y se ha estimado su concentración mediante un análisis racional. Los minerales de boro encontrados han sido: colemanita y ulexita, y además se han identificado: calcita, dolomita, cuarzo, celestina y oropimente. En la caracterización térmica se estudiaron las pérdidas de peso y las transformaciones térmicas características de las muestras objeto de estudio, cuando eran sometidas a un ciclo de calentamiento controlado. Palabras clave: Caracterización, colemanita, ulexita, boratos sintéticos, espectrometría FRX, espectrometría ICP-OES, DRX, análisis térmico, ATD, TG Chemical, mineralogical and thermal characterisation of natural and synthetic boratesThe present study establishes a methodology for characterising natural and synthetic borates used as raw materials in the ceramic industry, since detailed information on this subject is unavailable in the literature. Four natural borates, three colemanites of different richness and one ulexite, were analysed in addition to two synthetic borates, a boric acid and a borax pentahydrate. The following analytical techniques were used for the characterisation: X-ray fluorescence (XRF) spectrometry, inductively coupled plasma-atomic emission spectrometry (ICP-OES), potentiometry, X-ray diffraction (XRD), thermogravimetry (TG), and differential thermal analysis (DTA). In the chemical characterisation, the elements Si, Al, Fe, Ca, Mg, Na, K, Ti, Sr, As and S were analysed by XRF, B by ICP-AES and potentiometry and F by potentiometry ISE and XRF. In the mineralogical characterisation, the boron minerals and the accessory minerals were determined and their concentration was estimated by rational analysis. The boron minerals found were colemanite, ulexite, boric acid and borax pentahydrate and the accessory minerals were calcite, dolomite, quartz, celestine and orpiment. In the thermal characterisation, the samples were subjected to a controlled heating cycle and the thermal weight losses and characteristic transformations of the samples were s...

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“…The same group has also used several techniques for the chemical, mineralogical and thermal characterization of natural and synthetic borates used as raw materials in the ceramics industry. 248 Four natural borates (three colemanites and one ulexite) and two synthetic borates (a boric acid and a borax pentahydrate) were analysed using XRF (for Al, As, Ca, Fe, K, Mg, Na, S, Si Sr and Ti), ICP-OES (for B), potentiometry, XRD, thermogravimetry and differential thermal analysis. Another paper that has described the preparation and characterization of B containing ceramics has been produced by Gu et al 249 Nanocrystalline boron carbide (B 4 C) was prepared by a solvothermal reduction of carbon tetrachloride using metallic lithium in the presence of amorphous boron powder at 600 1C in an autoclave.…”