Research of metallurgical slags chemical composition, originating both from current production as well as gathered in dumping grounds formany years, show that they are very diversified. Slags contain substantial amounts of metals, including heavy metals, apart from elements from groups of non-metals and lanthanoids. In the article occurrence forms and relations with phase components of selected metals (iron, manganese, zinc, lead and others) on the basis of mineralogical and chemical research on slags after steel and ore Zn-Pb production were characterized. It was stated that metals may occur in metallurgical slags as fine drops not separated from slag during a metallurgical process, may form polymetallic aggregates, their own phases (especially oxide ones) and hide in structures of silicate phases. A considerable amount of metals is dissipated in glaze and amorphous substance. The conducted research delivers information on the occurrence of metals in metallurgical slags, which is extremely important during work connected with economic exploitation of slags. It especially refers to increasing attempts of acquiring elements from metallurgical slags. These activities determine the necessity of analyzing chemical and phase composition of slags because they may be an important indication, for instance while working on a proper technology of elements recovery.
Metallurgical slag is often treated as a material which could be used in the waste management, especially for production different kinds of aggregate. So it is necessary to know that material not only considering technical properties, but also its mineral and chemical composition. Such researches could deliver many valuable information during the waste utilization. Researches were made for samples of the metallurgical slag after steel and Zn-Pb production. Samples were taken from chosen dumps localized in the Upper Silesian District. Beside metallic aggregates, silicate and oxide phases, glaze is one of the main component of the metallurgical slag. The following stages of the glaze devitrification were presented; from not transformed and isotropic glaze pieces to the strong weathered glaze. Transformed glaze is red or brown with the cracks on the surface. Cracks are often filled by the metals oxides, which can be liberated during the glaze devitrification. On the base of researches executed using the electron microprobe the chemical glaze composition was presented. The chemical composition of the glaze is variable what is connected with the kind of the metallurgical slag. The following main elements were distinguished in the metallurgical slag: Si, Al, Fe, Ca and Mg. Slag after steel production contains also Mn, P, S and the slag after Zn-Pb production contains: As, Cd, Cu, Mn, Ni, Pb, Ti, Zn, Na, K, P and S.
The analysis of leaching behavior of harmful substances, such as arsenic, is one of the parameters of risk assessment resulting from the storage or economic use of coal waste. The leachability depends both on the environmental conditions of the storage area as well as on the properties of the waste material itself. There are a number of leaching tests that allow to model specific conditions or measure the specific properties of the leaching process. The conducted research aimed at comparing two methods with different application assumptions. The study of arsenic leaching from waste from the hard coal enrichment process was carried out in accordance with the Polish PN-EN 12457 standard and the US TCLP procedure. The leaching results obtained with both methods did not exceed the limit values of this parameter, defined in the Polish law. Both methods were also characterized by the good repeatability of the results. The use of an acetic acid solution (TCLP method) resulted in three times higher arsenic leaching from the examined waste compared to the use of deionized water as a leaching fluid (method PN-EN 12457). Therefore, the use of organic acid tests for mining waste intended for storage with municipal waste should be considered, as the results of the basic test based on clean water leaching may be inadequate to the actual leaching of arsenic under such environmental conditions.
Heavy metal pollutants in the leachate of waste landfill are a potential threat to the environment. In this study, the feasibility of using municipal sewage sludge as barrier material for the containment of heavy metal pollutants from solid waste landfills was evaluated by compaction test and hydraulic conductivity test concerning compaction property, impermeability and heavy metal retardation. Results of the compaction test showed that the maximum dry density of 0.79 g·cm−3 was achieved at the optimum water content of about 60%. The hydraulic conductivities of compacted sewage sludge permeated with synthetic heavy metal solutions were in the range of 1.3×10−8 – 6.2×10−9 cm·s−1, less than 1.0 ×10−7cm·s−1 recommended by regulations for barrier materials. Chemical analyses on the effluent from the hydraulic conductivity tests indicated that the two target heavy metals, Zn and Cd in the permeants were all retarded by compacted sewage sludge, which might be attributed to the precipitation and adsorption of heavy metal ions. The results of this study suggest that specially prepared material from sewage sludge could be used as a barrier for waste landfills for its low permeability and strong retardation to heavy metal pollutants.
The heavy metal release experiments were conducted in the laboratory to examine the effects of 3 factors - pH, dissolved oxygen (DO), and temperature on the metal release from sediments taken from the Huangpu River. The metal concentrations in the dry sediments ranged from 0.030 to 0.296 mg g-1 for Cr, 0.021 to 0.097 mg g-1 for Ni, 0.014 to 0.219 mg g-1 for Cu, 0.035 mg to 0.521 mg g-1 for Zn, 0.0002 to 0.001 mg g-1 for Cd and 0.023 to 0.089 mg g-1 for Pb. Most of the metals found in the sediments were in the form of residual fraction, the exchangeable fraction consisted of only a small portion of total metals. The average dissolved metal concentrations in the overlying water during the 13-day period under different conditions were ranging from 0.82 to 1.93 μg L-1 for Cr, 1.08 to 4.19 μg L-1 for Ni, 40.79 to 82.28 μg L-1 for Cu, 20.30 to 29.96 μg L-1 for Zn, 1.57 to 4.07 μg L-1 for Cd, and 22.26 to 75.50 μg L-1 for Pb, respectively. Statistical interpretation of the data indicated that pH (7, 8, 9), dissolved oxygen DO (1.0 and 5.0 mg L-1) and temperature (4, 16, 25°C) had no significant effects on the heavy metal release under the studied conditions. Cu and Pb had the highest release flux, while Cd, Pb and Cu had higher mobility. The main factors controlling the metals release might be the inherent characters of metals and sediments.
Among the elements that compose steel slags and blast furnace slags, metallic precipitates occur alongside the dominant glass and crystalline phases. Their main component is metallic iron, the content of which varies from about 90% to 99% in steel slags, while in blast furnace slags the presence of precipitates was identified with the proportion of metallic iron amounting to 100%. During observations using scanning electron microscopy and X-ray spectral microanalysis it has been found that the form of occurrence of metallic precipitates is varied. There were fine drops of metal among them, surrounded by glass, larger, single precipitates in a regular, spherical shape, and metallic aggregates filling the open spaces between the crystalline phases. Tests carried out for: slags resulting from the open-hearth process, slags that are a by-product of smelting in electric arc furnaces, blast furnace slags and waste resulting from the production of ductile cast iron showed that depending on the type of slag, the proportion and form of metallic precipitates is variable and the amount of Fe in the precipitates is also varied. Research shows that in terms of quality, steel and blast furnace slag can be a potential source of iron recovery. However, further quantitative analyses are required regarding the percentage of precipitates in the composition of slags in order to determine the viability of iron recovery. This paper is the first part of a series of publications aimed at understanding the functional properties of steel and blast furnace slags in the aspect of their destructive impact on the components of devices involved in the process of their processing, which is a significant operational problem.
Concentration of Zn, Cu, Cd, Pb and Co have been determined in Antarctic water (South Shetland Islands) and in krill exoskeletons with the help of atomic absorption spectrophotometry. Concentrations of these metals both in sea-water and in krill exoskeleton are in order Zn > Cu > Cd > Ni > Pb > Co. Comparing concentrations of these metals in sea-water to their concentrations in krill exoskeleton, the factors have been calculated giving a list of metals in the order of krill chitin ability, which is Ni > Cu > Zn > Cd > Pb > Co accumulation. The highest accumulation factors for Ni and Cu point out to the special role played by these metals in krill life.
Casting process takes a major percentage of manufacturing products into consideration. No-bake casting is swiftly developing technology for foundry industries. In the no-bake family, furan no-bake casting process employs resins and acid catalyst to form a furan binder system. However, this process configures castings with augmented strength and quality surface finish. Compressive strength, transverse strength and tensile strength of moulds are also high in this furan binder system. Hence this method is apt for producing accurately dimensioned castings. Our well thought-out deliberations in the subsequent write up entail the numerous effects of variation of resin and acid catalyst on the surface defect i.e. sulfur diffusion on the surface of FNB casting. Furan resin; used in the production of casting is furfuryl alcohol and acid catalyst is sulphonic acid. Sulfur diffusion is tested by Energy-dispersive X-ray spectroscopy (EDX) analysis and also by the spectrometer with jet stream technology. This paper also comprises economic advantages of optimizing resin because furan resin is expensive and catalyst with reduction of sulfur diffusion defect as it saves machining, labor cost, and energy.
The Copper-SiC composite was investigated with the help of FEM. The authors modeled and analyzed the effect of relaxation of thermal stresses due to seasoning at room temperature after the manufacturing process together with the effect of thermal stresses induced by reheating the material to a service temperature. Especially, hypothetical fracture at interface was of interest. It was shown that, for a fixed temperature, a single crack emanating at 0° or 45° azimuth would develop only along a portion of fiber perimeter, and a further growth would require stress increase in the fiber surrounding.
Metal contents in the tundra soils (Gelic Regosols, Gelic Gleysols, Gelic Cambisols) of the maritime lowland of Kaffiöyra, in the western Spitsbergen seashore are presented in this publication. The average heave metal contents in samples collected from the depth layer 0—130 cm are follows: Fe 2.9%, Mn 392 ppm, Zn 75 ppm, Cu 23.4 ppm, Ni 24.1 ppm, Co 7.4 ppm, Pb 12.5 ppm, Cd 0.24 ppm. The surface soil layer 0 to 25 cm is poorer in Ca and Mg than the underlying layer 25 to 130 cm. The heave metal contents like Fe, Mn, Ni and Co, are also somewhat lower in the upper layer. The enrichment indices of Pb and Cd are equal in the surface soil layer 1.16 and 1.23 respectively. Correlation coefficients between each studied element and organic carbon, and, on the other hand, soil separates < 20 μm and < 2 μm are very low.