Postupak prerade otpadne olovne alkalne šljake u korisne proizvode

Postupkom prerade otpadne olovne alkalne šljake u korisne proizvode, dobijaju se frakcija +1mm, koja sadrži korisne komponente (metalno sulfidne, čvrste, nerastvorne) i koja se vraća u proces topljenja u cilju valorizacije korisnih komponenti. Postupkom se takođe dobija frakcija -1mm (jalovinska oksidno – sulfatna), optimalnog sastava i strukture, pogodna za postupak stabilizacije i solidifikacije u cementnoj matrici betona radi primene u građevinarstvu. Postupak obuhvata ispiranje u cilindričnom rotirajućem ispiraču – odvajaču (temperatura 22-43oC, brzina mešanja 6-25min-1, odnos čvrsto tečno 10-28% čvrstog), pri čemu se uklanjaju u vodi rastvorne komponente iz šljake, dobija stabilnija šljaka (frakcija -1mm) i izdvaja povratni metal i kamenac (frakcija +1mm) sa sadržajem korisnih komponenata, koje se valorizuju vraćanjem u proces topljenja. Koristan proizvod je i rastvor nakon tretmana sodnog sadržaja, koji se koristi u procesu proizvodnje natrijum(I) – sulfata, zajedno sa rastvorom iz faze desumporizacije olovne paste prerade otpadnih olovnih akumulatora, u cilju dobijanja komercijalnog proizvoda Na2SO4

Disperzno ojačani materijali na bazi nanostrukturnih prahova u sistemu bakar-glinica

U okviru monografije, polazeći od teorijskog prikaza sinteze, strukture, svojstava i primene nanostrukturnih materijala, dati su originalni eksperimentalni rezultati uporedne analize različitim postupcima sintetisanih disperzno ojačanih nanostrukturnih kompozitnih Cu-Al2O3 materijala sledećih sistema: - nanokompozitnog Cu-Al2O3 sistema dobijenog mehaničkim legiranjem komercijalnog praha bakra dobijenog elektrolitičkim postupkom i glinice sintetisane sol-gel metodom, - nanokompozitnog Cu-Al2O3 sistema na bazi praha dobijenog termohemijskim postupkom, taloženjem iz tečne faze, - nanokompozitnog Cu-Al2O3 sistema dobijenog kombinacijom hemijskog postupka sinteze i mehaničkog legiranja

Synthesis of nanocomposites of difference architectures and applications based on copper, nickel and alumina

Considering that nanostructural materials are expected to have special physical and mechanical properties, in the recent years the examinations of synthesis and characterization of the nanocomposite system attracts even greater scientific interest. This paper presents production of sintered contacts materials produced from nanocomposite powders obtained by combination of thermochemical synthesis of Cu-Al2O3 powder and mechanical alloying of atomized copper powder with previously sinthetized Cu-Al2O3 powder. Produced powders were characterized by X-ray diffraction and Analytical Electron Microscopy. Characterization of sintered samples included Scanning Electron Microscopy (SEM), Energy Dispersive Spectrometry (EDS), measurement of hardness and specific electrical conductivity. By thermochemical method of Cu-Al2O3 nanocomposite synthesis, i.e. deposition from aqueous solutions, in combination with mechanical alloying, significant effects of reinforcement were achieved as a result of homogenous distribution of alumina in the nanocomposite system. In combination with conventional methods, thermochemical process of nanocomposite powders synthesis could be successfully applied for synthesis of new nanocomposite catalysts, which are characterized by a high degree of dispersion of the catalytically active component, respectively the catalyst with high activity and selectivity. The high degree of dispersion is the result of uniform distribution of the catalytically active component into alumina suspension, realized during the thermochemical treatment in the synthesis of nanocomposite catalysts. In accordance with this, the paper shows the synthesis of Ni/Al2O3 and Ni-Pd/Al2O3 nanocomposite catalysts with homogeneously dispersed Ni particles, as catalytically active component, and Pd, as activity modifier, supported on ceramic Al2O3 based foam. Namely, the previous synthesized monolith was soaked in a mixed alumina suspension with NiCl2, PdCl2 and appropriate organic additives in order to obtain a nanocomposite catalysts with homogeneous distribution of catalytically active components. Characterization of obtained Al2O3 foam, as the active catalytic components primary carrier, and synthesized nanocomposite catalysts included SEM, EDS, gas permeability and mechanical properties. Synthesis of nanocomposite materials with homogeneous distribution of particles on the nanometer level may lead to formation of new materials with improved or even unexpected properties

Synthesis and Characterization of Dispersion Reinforced Sintered System Based on Ultra Fine and Nanocomposite Cu-Al2O3 Powders

Characterization of the obtained powder indicates a possibility of the synthesis of nanocomposite Cu-Al2O3 system by the thermochemical procedure, starting from water solutions Cu(NO3)2 and Al(NO3)3. AEM analysis indicates the presence of individual particles of 20-50 nm size. The shape of particles is irregular, with the presence of individual particles of nodular shape. The surface morphology is rough. Apart from that, the presence of an agglomerate with the magnitude of >100nm and of a sponge shape is noticeable. The obtained nanocomposite powders, with the structure basically preserved together with the final product, provided a significant reinforcement effect in the obtained sintered system. This is a consequence of the homogenous distribution of the elements in the structure, accomplished during the synthesis of powder and presence of the third phase which causes stabilization of dislocation substructure and achieves the relevant reinforcing effect. The analysis of the mechanical and electric properties of the sintered Cu-Al2O3 systems based on powders obtained by the thermochemical method shows that in the system with 3wt.%Al2O3, sintered at 900ºC, structural stabilisation occurs only after 30 minutes with considerable reinforcement effects. Since in other systems, the structural stabilisation process was not completed even after 120 minutes, the system with 3wt.% of dispersoids sintered at 900ºC for 30 minutes seems to be the optimum solution for the production of dispersively reinforced Cu-Al2O3 systems. This statement is confirmed by the corresponding analysis of the microstructure. In accordance with the previous statements, the EDS analysis of the sintered systems surface as well as FIB analysis show a homogenous distribution of elements, i.e. present phases. FIB analysis also indicates the size of microstructural constituents within the range of 50-250nm. TEM analysis of the sintered systems reveals the presence of copper crystals of 100 nm in size exposed to twinning, thus pointing to stabilization of the dislocation substructure. SADP of the examined nanocomposite Cu–Al2O3 sintered system shows spots and rings, where spots refer to the individual crystals of copper, and sharp circles (rings) originate from nanocrystals of alumina dispersed in the copper matrix. HRTEM analysis indicates the changes in the lattice parameter, which leads to the conclusion that the eutectic reaction occurred and the third, CuxAlyOz phase was formed on the grain boundary, which will be the subject of future studies based on a more precise approach to physical chemistry of system surfaces and of thermodynamic examinations of the influences of finely dispersed Al2O3 on the formation of the third phase and the increase in the system surface energy. In the end, all the above-mentioned examinations show that the reinforcement of Cu-Al2O3 system occurs via two mechanisms, which are: dispersion and reinforcement mechanism due to the homogenous dispersion of fine particles of Al2O3 in the matrix, and the mechanism of grain boundary reinforcement due to the appearance of the third phase

Innovative solutions for the extraction of technology metals from complex primary a nd secondary raw materials

Technological evolution and growing demand for various high-tech devices have increased need for metals, both in terms of their diversity and quantities, resulting in more intense use of natural resources and generation of huge amounts of various waste materials. In contrast to base metals, advances in material science have given rise to a new group of metals, which are used in small or trace amounts to alter drastically the properties of matter. Whether in composite materials, like semiconductors or minor elements in alloys, these trace metals shape modern-day technology and, hence, are termed as Technology Metals (TM). Metals such as Sb, Co, Ga, Ge, In, Ta, the Platinum Group Metals (PGMs) and the Rare Earth Elements (REEs) are among the TM in which Europe is 100% import dependent. Development of the novel processing technologies will aim not only in securing raw material supply, but will rather aim to establish sustainable metallurgical processing, meaning establishing technologies for de-complexing the advanced material products with the minimum environmental footprint. Hydro and electro metallurgical steps make essential base with synergy to primary production route, advanced mechanical and minor pyro pretreatment step. However, absence of such extraction technologies, successfully applied on industrial scale, is still notable. To secure a reliable and sustainable supply of critical materials, innovative solutions need to be developed along the entire value chain. This transition requires multi-stakeholder partnerships that foster innovation and entrepreneurship, which can be obtained by applying the Triple Helix concept. Presented compilation of scientific, theoretical and experimental results, promotes an innovative synergy of various metals and industrial activities in metallurgy, resulting in profitable transformation of by-products and waste materials into resources. Focusing on treatment of specific by-products from zinc and copper primary production, as well on specific waste streams like WEEE and waste automotive catalysts, group is actively contribute to the EU sustainability policies

Positive synergistic effect of the reuse and the treatment of hazardous waste on pyrometallurgical process of lead recovery from waste lead-acid batteries

Modification and optimization of the pyrometallurgical process of lead recovering from the waste lead-acid batteries have been studied in this paper. The aim of this research is to develop a cleaner production in the field of the secondary lead metallurgy. Lead smelting process with the addition of flux (sodium(I)-carbonate) and reducing agents (coke, iron) has been followed. The modified smelting process with the addition of hazardous waste (activated carbon) as alternative reducing agents has shown positive results on the quality of the secondary lead, the generated slag and the process gases. Filtration efficiency of the gases, the return of baghouse dust to the process and use of oxygen burners have positive effect on the environment protection and energy efficiency. Optimization of the recycling process has been based on the properties of the slag. Stabilization of slag is proposed in the furnace with addition of waste dust from the recycling of cathode ray tube (CRT) monitors. Phosphorus compounds from dust reduce leachability of toxic elements from the generated slag. Reduction the slag amount and its hazardous character through the elimination of migratory heavy metals and valorization of useful components have been proposed in the patented innovative device - cylindrical rotating washer/separator.  http://dx.doi.org/10.5937/metmateng1403171

Sintering of Cu–Al2O3 nano-composite powders produced by a thermochemical route

This paper presents the synthesis of nano-composite Cu–Al2O3 powder by a thermochemical method and sintering, with a comparative analysis of the mechanical and electrical properties of the obtained solid samples. Nano-crystalline Cu–Al2O3 powders were produced by a thermochemical method through the following stages: spray-drying, oxidation of the precursor powder, reduction by hydrogen and homogenization. Characterization of powders included analytical electron microscopy (AEM) coupled with energy dispersive spectroscopy (EDS), differenttial thermal and thermogravimetric (DTA–TGA) analysis and X-ray diffraction (XRD) analysis. The size of the produced powders was 20–50 nm, with a noticeable presence of agglomerates. The composite powders were characterized by a homogenous distribution of Al2O3 in a copper matrix. The powders were cold pressed at a pressure of 500 MPa and sintered in a hydrogen atmosphere under isothermal conditions in the temperature range from 800 to 900 °C for up to 120 min. Characterization of the Cu–Al2O3 sintered system included determination of the density, relative volume change, electrical and mechanical properties, examination of the microstructure by SEM and focused ion beam (FIB) analysis, as well as by EDS. The obtained nano-composite, the structure of which was, with certain changes, presserved in the final structure, provided a sintered material with a homogenеous distribution of dispersoid in a copper matrix, with exceptional effects of reinforcement and an excellent combination of mechanical and electrical properties

Ni-Pd-Al2O3 catalyst supported on reticulated ceramic foam for dry methane reforming

In the present study, Ni-Pd/Al2O3 catalyst supported on α-Al2O3 based foam was prepared and evaluated in the dry methane reforming process. Corresponding metal chlorides were deposited to the foam surface by impregnation of the foam with ultrasonically aerosolized salt solutions at 473 K and drying at that temperature. Calcination step was excluded and the catalyst was reduced at very low temperature - 533 K. The reforming experiment lasted for 3 h, with standing time of 1 h at the following temperatures: 873, 973 and 1023 K. Conclusions on selectivity, catalytic activity and stability were reached on the basis of CO and H2 yields