Effects of dry grinding on pyrophyllite

Abstract

Dry grinding of pyrophyllite (Hillsboro, USA) has been studied by X-ray diffraction (XRD), specific surface area measurements (BET) and scanning electron microscopy (SEM). At the beginning of the grinding process, some effects such as delamination, gliding and folding of the layers, and decrease in particle size were detected by SEM and XRD, resulting in a large increase in specific surface area, up to a maximum of ~ 60 m 2 . g-1. Marked changes in the structure take place between 30 and 32 mins grinding. Longer grinding times increase the degree of disorder and SEM and specific surface area data suggest that aggregation occurs. XRD results indicate that some residual order persists in the degraded structure.

Influencia de los tratamientos mecánicos y térmicos en materias primas que contienen pirofilita

“…6 shows the surface area results of samples PyH and ZS plotted as a function of grinding time. The increase of surface area of PyH sample is interpreted due to a diminution of particle size as a consequence of grinding treatment (22,23). This is produced up to reach a limit of mechanochemical reduction estimated in a size of ca.…”

“…El aumento de superficie específica de la pirofilita PyH se interpreta debido a la disminución del tamaño de las partículas por molienda (22,23), hasta que se llega a un límite de reducción c-axis of the original silicate crystal structures. As a consequence, layer silicate minerals show a pronounced propensity towards cleavage perpendicular to one crystalline axis (19,20).…”

“…Se produce entonces una disminución progresiva de los valores de superficie específica hasta valores en torno a 8,4 m 2 /g a los 240 minutos y un valor medio estimado del tamaño de las partículas de 0,26 µm. Estos cambios se pueden seguir, asimismo, por MEB (22,26,27). Por molienda se forman aglomerados irregulares y progresivamente más densos, comprobándose la destrucción del carácter laminar inicial.…”

“…After this, a progressive decrease in surface areas is observed with formation of agglomerated particles by the progressive grinding up to values of 8,4 m 2 /g after 240 minutes with equivalent spherical particle size of 0.26 µm. These mechanochemical changes can be followed by electron microscopy (22,26,27). The irregular agglomerates, progressively denser, are formed by dry grinding of PyH and ZS pryophyllite samples, with destruction of the layered shape initially present.…”

Adsorption of Aromatic (BDMHDA-Cl) and Aliphatic (HDTMA-Cl) Amine by Sepiolite

“…(1) Öğütülmüş sepiyolitin SEM görünümü, sepiyolitik bünyede bulunan ve öğütme işlemi sonrasında kısmen serbestleşen liflerin yassı tanelere ve pullara dönüştüğünü göstermekte ve bu durum, öğütme esnasında oluşan amorf tabaka yüzeylerinin birbirine yapışması veya öğütme sonucu yapısı bozunmuş ve boyutu küçülmüş liflerin ortamda çimento etkisi yaparak büyük boyutta aglomera olmuş taneciklerin şekillenmesine neden olmaktadır (Cornejo and Hermosin, 1988;Perez-Rodriguez et al, 1988).…”