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Natural zeolites, a family of hydrated aluminosilicates, are important raw materials for micro and nano technologies due to their molecular-sieve, ion-exchange and catalytic properties. Their porous crystalline framework is built from alternating SiO4 and AlO4 - tetrahedra forming cages and channels, and improvement of zeolite performance is possible by thermal and chemical treatment. The influence of hydrochloric acid and calcination on heulandite-containing tuff from the Georgian Dzegvi-Tedzami deposit was studi...

Old closed uranium mines can be a significant source of environmental pollution and hazards to human health. The problem could become more severe in time due to erosion if the restoration measures are not properly maintained. There are many uranium mines in Bulgaria that, even closed in the 1990s, could be a pollution source for surface and groundwater in their region. Through hydraulic connections, they can contaminate the rivers passing nearby. The aim of the present work was to check the hypothesis of a possibl...

Purified natural clinoptilolite as well as clinoptilolite converted into hydrogen and sodium form have been contacted with 0.1 mol/L silver nitrate solution at a ratio solid to liquid equal to 1 to 20, in order to load silver ions (Ag+) on the zeolite support. It has been found that sodium modified clinoptilolite exchanged in highest degree Ag+ ions, followed by natural zeolite. Preliminary transformation of natural clinoptilolite into hydrogen form leads to decreasing of zeolite ability to bind Ag+ ions. The kine...

The ore extraction from Krumovo deposit, located at the northern periphery of the Manastir heights in Southeast Bulgaria started in 1906 and continued till 1986. The ore comprised Fe3O4 with admixtures of sulfides such as pyrite, pyrrhotite, marcasite and chalcopyrite. Open pits and underground workings were used. The excavations severely degraded the habitats, vegetation and waters on an area of about 3 km2. By 1986 waste rock (comprising hydrothermally altered basic magmatic rocks, such as gabbro or diorites, ma...

The paper describes results from 18 months data collection and analogue modeling of “rain water – calcrete” interaction. The expe riment is based on leaching by natural rain and snow-melting water of material from diff erent soil and undersoil layers, containing various amounts of carbonates. It confirme d that rain and snow-melting water, circulating through the soil, undersoil and the underlying rocks, dissolves calcium rich minerals. Under dry weather and relativel y high temperature the hydrogen carbonat...