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Treatment of the acidic effluent from a copper smelter by flotation tailings
No full textSince commissioning in 1961, the copper mine Majdanpek, a part of the Mining and Smelting Complex Bor (RTB Bor), produced approximately 378 million tons of flotation tailings. Semiquantitative mineralogical analysis of the flotation tailings revealed significant content of carbonate minerals (approximately 20-25 %), indicating high acid neutralization capacity. Also, approximately 70 % of copper is in the form of the oxide mineral cuprite (Cu2O). Copper can be easily leached from cuprite by using sulphuric acid. The RTB Bor copper smelter generates 8.7 m(3)h(-1) of extremely acidic waste effluent (142.4 kgm(-3) of sulphuric acid, pH - 0.464) with relatively high concentrations of dissolved metals and metalloids (Cu, Fe, Zn, Pb and As). The effluent is currently treated with hydrated lime. The present study focused on application of flotation tailings as a neutralizing agent for acidic effluents. Laboratory experiments followed by computer simulation of the industrial process showed that 99% of the acid can be neutralized with flotation tailings in a series of six reactors resulting in the final copper concentration of 1.55 gL(-1). Benefits of the proposed process are: lower environmental impact of the process and reduced costs of neutralization of the acidic effluent from the copper smelter
Copper leaching from chalcopyrite concentrate by sodium nitrate in sulphuric acid solution – chemometric approach
No full textHydrometallurgical processing of the copper concentrates is a promising alternative to the conventional pyrometallurgical production of copper due to significantly lower environmental impact, capital and operational costs. Development of the hydrometallurgical process for copper recovery from mineral concentrate requires extensive work in testing and optimization of operational parameters from laboratory to semi-industrial scale. Mathematical modelling of the copper leaching process can save human labour and time. Leaching of copper from chalcopyrite concentrate using sulphuric acid and sodium nitrate as an oxidant was tested, and the influence of temperature, particle size, stirring speed and concentrations of sulphuric acid and sodium nitrate were evaluated. Obtained results showed that increasing temperature and concentrations of sulphuric acid and sodium nitrate increase the leaching degree of copper, while increasing particle size and stirring speed reduce copper extraction. In this paper, second-order polynomial models (SOP) were applied to experimental data. Presented results show that mathematical models fit experimental data. The conclusion is that SOP models are a promising tool to be used for modelling leaching processes of metals
Leaching of chalcopyrite concentrate by hydrogen peroxide in sulphuric acid solution
No full textPrimena hidrometalurških procesa omogućava proizvodnju metala iz ruda i koncentrata koji, zbog kompleksne mineralogije i/ili niskog sadržaja metala, nisu pogodni za pirometaluršku preradu. Pored toga, manja potrošnja energije i manji uticaj na životnu sredinu su važne prednosti hidrometalurgije u odnosu na konvencionalne pirometalurške procese. Prilikom luženja sulfidnih minerala sumpornom kiselinom rastvor za luženje mora sadržati oksidaciono sredstvo za oksidaciju sulfidnog sumpora. U ovom radu je ispitivan uticaj temperature na stepen izluženja bakra iz halkopiritnog koncentrata u prisustvu vodonik-peroksida kao oksidansa pri atmosferskom pritisku. Hemijska i rendgenska difrakciona analiza polaznog koncentrata i čvrstog ostatka nakon luženja su korišćene za određivanje mehanizma procesa luženja bakra iz ispitivanog koncentrata.Due to complex mineralogy and/or low content of base metals, some ores and mineral concentrates are not suitable for pyrometallurgical treatment. Therefore, those ores and concentrates have to be treated by application of the hydrometallurgical processes. Lower energy consumption and lower environmental impact are important advantages of hydrometallurgy over pyrometallurgy. Leaching of sulphide minerals requires presence of oxidants in acidic environment. Influence of temperature on leaching degree of copper from chalcopyrite in presence of hydrogen peroxide under atmospheric pressure was investigated in this paper. Results of the chemical and X-ray diffraction analysis of the concentrate and leaching residue were used in order to explain mechanism of the copper leaching from the mineral concentrate
Gentamicin-loaded bioceramic composite coating aimed for biomedical use
No full textElectrophoretic deposition (EPD) process was successfully used for
obtaining composite antibacterial coating of antibiotic gentamicin (Gent), natural polymer
chitosan (CS), and hydroxyapatite (HAP). EPD was carried out on pure titanium (Ti) plates in
a single step from three-component aqueous suspension. The gentamicin influence was
examined through detailed physico-chemical and biological characterization. The formation
of composite HAP/CS and HAP/CS/Gent coatings on the titanium surface was confirmed by
X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier
transform infrared spectroscopy (FTIR) and X-ray photoelectron analysis (XPS). Composite
HAP/CS and HAP/CS/Gent coatings exhibited homogeneous, porous fracture-free surface,
suggesting strong interfacial interactions between HAP and CS. Biological assays pointed to
high potential of HAP/CS/Gent coating for medical applications. Test in suspension and agar
diffusion method indicated that the gentamicin addition strongly influenced the antibacterial
activity of HAP/CS/Gent against Staphylococcus aureus and Escherichia coli.
Biocompatibility assays were performed through MTT and DET tests, indicating low
cytotoxicity against MRC-5 and L929 tested cell lines. The coating ability to induce and
promote osteoconduction was proved by ALP assay suggesting that HAP/CS/Gent coating is
an excellent material for bone tissue engineering
Potentiality of obtaining mica flotation concentrate from kaolinised granite
No full textThis study shows the results of flotation concentration of mica minerals from kaolinised granite taken from the "Basica bare" deposit - Kobas, Srbac, The Republic of Srpska (B&H). Mineralogical composition of kaolinised granite is as follows: kaolinite, feldspar, quartz, and mica. After separating >0.630 mm, and LT 0.043 mm size class where kaolinite is concentrated, the rest is -0.630+0.043 mm class containing quartz, feldspar and mica. The mica concentrate was obtained by the flotation concentration, while feldspar and quartz were in the flotation underflow. According to the mineralogical analysis, the most abundant minerals are mica and chlorite/clays, while quartz and feldspar occur much less, and accessory minerals are represented in trace. The semi-quantitative mineralogical analysis obtained by the X-ray powder diffraction (XRPD) method of the mica concentrate amount to: mica approximate to 55%, chlorite/clays approximate to 35%, quartz approximate to 5%, feldspars (plagioclase and K-feldspars combined) approximate to 5%
Kinetics of thermally activated processes in cordierite-based ceramics
No full textThermally activated processes in cordierite-based ceramics were investigated to determine the effect of the mechanical activation and the addition of TeO2 on kinetic and thermodynamic parameters of these processes. Using a combination of dilatometry and DTA measurements in the 100-1400 degrees C temperature range, it was established that both the mechanical activation and the addition of TeO2 have a significant effect on processes in cordierite-based ceramics. A combination of 5 mass% addition of TeO2 and mechanical activation for 40 min reduced the sintering temperature of cordierite ceramics to around 1100 degrees C. In addition, the analysis of DTA measurements of mechanically activated samples indicates that the mechanical activation leads to intensification of the cordierite formation through an increase in concentration of surface defects and an increase in grain contact surface in the initial powder
Kinetics of Chalcopyrite Leaching by Hydrogen Peroxide in Sulfuric Acid
No full textIn ores, chalcopyrite is usually associated with other sulfide minerals, such as sphalerite, galena, and pyrite, in a dispersed form, with complex mineralogical structures. Concentrates obtained by flotation of such ores are unsuitable for pyrometallurgical processing owing to their poor quality and low metal recovery. This paper presents the leaching of chalcopyrite concentrate from the location "Rudnik, Serbia". The samples from the flotation plant were treated with hydrogen peroxide in sulfuric acid. The influences of temperature, particle size, stirring speed, as well as the concentrations of hydrogen peroxide and sulfuric acid were followed and discussed. Hence, the main objective was to optimize the relevant conditions and to determine the reaction kinetics. It was remarked that the increase in temperature, hydrogen peroxide content, and sulfuric acid concentration, as well as the decrease in particle size and stirring speed, contribute to the dissolution of chalcopyrite. The dissolution kinetics follow a model controlled by diffusion, and the lixiviant diffusion controls the rate of reaction through the sulfur layer. Finally, the main characterization methods used to corroborate the obtained results were X-ray diffraction (XRD) as well as qualitative and quantitative light microscopy of the chalcopyrite concentrate samples and the leach residue
Structure and Microstructure Characterization of the La2SrB10O19 Glass-ceramics
No full textThe crystal structure of new lanthanum strontium borate glass-ceramics was refined by the Rietveld method. The results showed that La2SrB10O19 has the monoclinic crystal structure, space group C2 (No. 5) with a = 11.1170(6), b = 6.5667(3), c = 9.2363(3) angstrom,beta = 91.481 degrees, V = 674.04(7) angstrom(3), two formula units per unit-cell, and density 3.830 g cm(-3). The main building units of the crystal structure are BO4 tetrahedra and BO3 triangles. Clusters composed of [B5O12] form an infinite double layer running perpendicular to the c-axis. Lanthanum atoms, situated in [B5O12](n) layers, are coordinated with 10 oxygen atom in a form of LaO10 polyhedra, while Sr atoms, located between [B5O12](n) layers, are coordinated with 8 oxygen atoms in a form of SrO8 polyhedra. Microstructural measurements contain both crystallite domain sizes and microstrain calculations obtained by the Warren Averbach and the simplified integral-breadth methods
Comparing ceramic technologies: The production of Terra Sigillata in Puteoli and in the Bay of Naples
No full textArchaeological excavations carried out in the sites of Rione Terra and Via Fascione in Pozzuoli (ancient Puteoli, Italy) unearthed samples of Red Slip Ware attributed to Terra Sigillata from Puteoli and Produzione A della Baia di Napoli, which are among the most important ceramic classes produced in Campania region and circulating in the Roman Empire from the 1st century BCE. Archaeometric analyses performed on twenty-one samples highlighted that stylistic and typological features are connected to technological ones, permitting to clearly distinguish the two different productions. The samples of Terra Sigillata showed fine-grained ceramic bodies, high-CaO content (on average 15.6 wt%), abundant microfossils along with quartz, feldspar and micas. The thin red slip, present on both inner and outer surfaces, appears sintered and well preserved. Sintering degree and mineralogical assemblages suggest that the artefacts experienced high firing temperatures (often exceeding 900 degrees C). On the other hand, the Produzione A samples contain a lower micro-fossils amount and rare volcanic grains. The vessels are covered by a thinner and non-sintered red slip compared to that of Terra Sigillata. Mineralogy and microstructures of the ceramic bodies also suggested lower firing temperatures (850-900 degrees C). Then, the technology and the exploited clayey raw material were different in the production areas probably highlighting different cultural influences as well as different commercial paths. Finally, the comparison with available data on italic Red Slip Ware allowed us to find some key-parameter for discerning the most important production areas
Dissolution of coal fly ash glass in different media
No full textThe increasing production of fly ashes from carbon combustion in thermal power plants has compounded environmental problems worldwide. As one of promising solution the vitrification of fly ashes could be considered. For potential application chemical durability of material should be known. Dissolution of coal fly ash glass grain samples was studied. The glass was obtained by melting a mixture of coal fly ash, Na2CO3 and CaCO3 at T= 1500 oC and quenching the melt in air. The chemical durability of the glass was determined by dissolution test in distilled water, HCl and NaOH at T = 950C for t =2h. It was shown that dissolution rate of glass in distillated water and NaOH is negligible, while in HCl solution was shown significant mass loss