Abstract

Damages (accidents) at the flotation tailing dumps could cause at one area an ecological disaster of small or great sizes. Due to this, the investigations of such appearances are carried out for the aim of defining the executive analytical-mathematical models for estimation the dangers of possible accidents. Mathematical models for simulation of accident flow at flotation tailing dump, given in this work, are defined based on an analysis of an actual accident flow at “Valja Fundata” flotation tailing dump in
Majdanpek (Serbia) in 1974. The evaluation of the eventual accident at any flotation tailing dump based on mathematical models given in this paperwork, could be done for any case where the height of flow over the abyss is sless than 117 m, while the average cross cut surface of the damage hole is up to 2.2 m² .

Abstract

This paper gives a presentation of primary crushing at stone aggregates production plant from deposit “Suvodo”. The paper has been developed from The Main Mining Project of the new processing plant for
limestone and production of stone aggregates from deposit “Suvodo”-A.D.- Jelen Do. First problem to be solved at primary crushing was the removal of waste rock being occurred in the useful component by mining. This one together with other problems has been solved in the laboratories of ITNMS and further on, at the operating plant itself.

Abstract

In the Maramures County, on the Cavnicului Valley, there is three tailing ponds belong to the Cavnic Mining Company from C.N.M.P.N. REMIN Baia Mare: Vranicioara, Malaini and Plopis-Rachitele. This paper
presents an analysis from physical and chemical stability point of view. The conclusion is that Vranicioara and Plopis-Rachitele waste deposits present stability from sliding point of view, but there is not secure in extremely meteorological or seismical conditions.

Abstract

The paper considers changes of mineralogical composition depending on firing temperature of Zorka brick clay. Research of the influence of firing temperature on mineralogical composition was performed on fraction samples with particle size up to 5μm of studied clay and subjected to thermal treatment at temperature of 600 ^oC, 800 ^oC, 1000 ^oC and 1200 ^oC. The samples were then subjected to X-ray diffraction analysis (RDA) and to examinations by scanning electron microscopy (SEM).
Zorka brick clay at firing temperature of 600 ^oC shows presence of distinct porosity with clay mineral dehydration process as well as formation of Hematite as a new phase due to present iron hydroxide, while mica remains untransformed at this temperature. At temperature of 800 ^oC,
rounding of grain borders takes place and mica phase into the basic mass which is made of transformed amorphous clay minerals. At 1000 ^oC,appearance of Melilite can be noticed, while reduction of mica quantity is noticeable due to hydration at this temperature. It can be also stated here
that porosity with appearance of glassy phase is present here. At firing temperature of 1200 ^oC, presence of glassy phase which fills space within the present Mullite and Melilite aggregate is noticeable. Presence of Hematite is also noticed here, as well as presence of relict remaining of feldspar. Porosity still exists, but at lower level compared to the one stated
during the study of sample from the same raw material fired at previous temperature, which is consequence of considerably more distinct presence of glassy phase in this case.
It was found that during firing Zorka brick clay had the characteristic to develop mineralogical phases of Hematite, Melilite and Mullite. In this clay the decrease of porosity by increase of firing
temperature was found as well as some presence of glassy phase which also was proportional to the increase of firing temperature.

Abstract

The structural, surface and pore properties of synthesized iron oxide samples were studied. The iron oxide samples were prepared by a chemical method at selected temperatures of 20 and 85°C. The changes in the structure were investigated using X-ray diffraction analysis. The scanning and transmission electron microscopy were used to characterize the shape and the size of particles and the pore structure characteristics were obtained from the nitrogen adsorption experiments. It followed from the experiments, that the temperature of synthesis influences the structural parameters of iron oxide particles.

Abstract

The contribution deals with high gradient magnetic separation (HGMS) of fly ash from thermal power plant Nikola Tesla B (Serbia). The lignite fly ash was subjected to wet grain size analysis, dry and wet HGMS
at the magnetic field induction of 0.09 T. As to iron content in magnetic product, the best result has been achieved by wet HGMS under application of potato starch as an additive, namely 27.43 % of Fe comparing to 3.20 % of Fe in a feed. Consequently, products of classifying and magnetic separation were subjected to microscopy, SEM, XRD and Mössbauer spectroscopy. Quartz was found as a dominant mineral, which is accompanied by plagioclase, calcite, magnetite and hematite. Mullite, fayalite and mayenite can also occur in fly ash. Mössbauer spectroscopy confirmed, that 57.8 % of iron is bonded in magnetite and 27.6 % in hematite.

Abstract

In processes such as coal flotation, the surface properties of coal- pyrite and other types of gangue presents in coal plays a major role in determining its separation from coal. Oxidation also leads to the formation of various oxygen functional groups and soluble inorganic that can adsorb on the coal surface and modify its wettability and floatability. These groups have remarkable impacts on surface charge, which controls film-thinning process and thus flotation kinetics [1].
In the previous studies, it was found that the results of coal flotation are lower than the results that are expected in consideration on the natural floatability of coal from anthracite mine “Vrška Čuka”. The slight decreased in the coal recovery and increased concentrate ash content may be explained by oxidation of coal [6].
Oxidation kinetics and effect of oxidation on hydrophobicity of fresh surfaces of coal, coal-pyrite and alumo-silicate minerals has been investigated through electrokinetic’s, microflotation and standard flotation studies in systems open to the atmosphere. A good correlation was obtained between the zeta potential and floatability. Results from all electrochemical tests confirme negatively effect of oxidation on the coal recovery and also the final effect of coal flotation process.