Abstract
Clinoptilolite is a precious zeolite mineral that has the most comprehensive physicochemical properties among all the zeolite group minerals. Due to these unique properties, clinoptilolite has a wide range of applications in many different industries. In Poland, the clinoptilolite occurs only as an accompanying mineral in the sedimentary rocks nearby Rzeszów. In Europe, the abundant clinoptilolite-bearing deposits are located in Slovakia and Ukraine, where clinoptilolite mineralization occurs in the volcanic tuffs. Due to clinoptilolite’s rare performance, it is extremely crucial to manage its deposits in a complementary manner. In this paper, the mineralogical and structural characterization of the clinoptilolite powders obtained by mineral processing of the clinoptilolite-rich tuffs from Slovakia and Ukraine deposits were discussed. The scope of research covered determination of the mineral composition of the tuffs, structural analysis of the clinoptilolite crystals, as well as textural and physical properties of the powders obtained by mineral processing of the tuffs. In addition, this paper includes the comparative study of the most significant zeolite deposits in the world and investigated clinoptilolite-rich tuffs. A wide spectrum of methods was used: X-ray powder diffraction (XRD), thermal analysis (DSC, TG), X-ray fluorescence (XRF), optical microscopy, Scanning Electron Microscopy (SEM-EDS), the laser diffraction technique, and low-temperature nitrogen adsorption/desorption. The test results indicated that the major component of the tuffs is clinoptilolite, which crystallized in the form of very fine-crystalline thin plates. The clinoptilolite mineralization in the Ukrainian and Slovakian tuffs exhibited a strong resemblance to the clinoptilolite crystals in Yemeni and Turkish tuffs. With respect to the mineral composition, the investigated tuffs showed excellent conformity with the Miocene white tuffs from Romania. The Ukrainian and Slovakian tuffs do not reveal the presence of the clay minerals, which is quite common for naturally occurring zeolite-rich rocks in various deposits in the world. The textural features together with mineral composition of the investigated samples incline that they are potentially suitable raw materials for the sorbent of petroleum compounds. Moreover, the obtained results can be useful indicators with respect to the crushing and compaction susceptibility of the Ukrainian and Slovakian clinoptilolite-rich tuffs.
Highlights
IntroductionZeolites are microporous aluminosilicates with a three-dimensional network composed of SiO4 and AlO4 tetrahedra joined by oxygen atoms
The investigated clinoptilolite-rich tuffs are light-colored with the shade of white for the Ukrainian tuff and green for the Slovakian (Figures 1 and 2)
The Slovakian tuff can be marked out by the larger mineral assemblages disseminated through the rock (Figure 2)
Summary
Zeolites are microporous aluminosilicates with a three-dimensional network composed of SiO4 and AlO4 tetrahedra joined by oxygen atoms. Depending on a certain zeolite type, the Si/Al ratio in its framework is changeable, but the Si content is always higher than the Al content. In the crystalline framework of zeolites, the specific system comprised of the channels and chambers with certain shape and size is observed. The channels and chambers are occupied by some cations and removable 4.0/). The size distribution of the channel system in the zeolite framework is significantly important when it comes to its sorption and catalytic properties [1,2,3]
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