Wyniki wyszukiwania - BazTech

1

The Effects of Microwave-Assisted Leaching on the Treatment of Electric Arc Furnace Dusts (EAFD)

Laubertova M., Havlik T., Parilak L., Derin B., Trpcevska J.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

321--328

EN

In this study, laboratory-scale experiments were carried out to investigate the effects of microwave-assisted alkaline leaching on the treatment of electric arc furnace dusts to recover zinc and lead. Microwave treatment is a new innovative technology in waste treatment and now is an attractive advanced inter-disciplinary field and also environmental friendly. The highest zinc extraction, 50.3% in 60 minutes using 5 M NaOH at 750 W and L:S ratio 20, and lead extraction up to 92.84% was achieved in these same conditions but in 30 minutes. Compared with conventional leaching, the top extraction rate using MW-assisted leaching was higher by 16% (Zn) and 26% (Pb). Zinc presents in the flue dust in the form of franklinite (ZnFe2 O4 ), its leaching in sodium hydroxide does not occur under the examined conditions, because it is enclosed in a matrix of iron.

2

Kinetic study of zinc leaching from sal-ammoniac flux in acidic media

Smincakova E., Trpcevska J., Piroskova J., Blaskova K.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 1

31--36

EN

This paper presents the results of the laboratory investigation of acid leaching of sal-ammoniac flux. Sal-ammoniac is waste product originated during wet hot dip galvanizing process having about 40 % of zinc. Zinc is the most abundant element in the sal-ammoniac flux and in the supplied sample was occurred in the form of following phases: Zn5(OH)8Cl2 H2O in amount of 70.83 %, (NH4)2(ZnCl4) in amount of 24.02 % and ZnCl2(NH3)2 in amount of 5.5 %. Leaching test of sal-ammoniac flux in distilled water and aqueous solution of hydrochloric acid has been carried out kinetically. The experimental parameters of HCl concentration, leaching time and temperature were varied. The results obtained are as follows: The apparent activation energy of leaching reaction by hydrochloric acid solution was Ea = 6.28 kJ mol-1. The apparent order of reaction n = 0.33 was estimated.

PL

W artykule przedstawiono wyniki badań laboratoryjnych kwaśnego ługowania odpadowego salmiaku. Salmiak ten jest produktem powstającym podczas gorącej zanurzeniowej galwanizacji zawierający ok. 40 % mas. cynku. Cynk jest pierwiastkiem występującym w największej ilości, dostarczona (badana) próbka zawierała następujące fazy: Zn5(OH)8Cl2 H2O — 70,83 %, (NH4)2(ZnCl4) — 24,02 % i ZnCl2(NH3)2 — 5,5 %. Testy ługowania prowadzono w wodzie destylowanej i w wodnych roztworach kwasu solnego. W testach zmiennymi parametrami były: stężenie HCl, czas i temperatura ługowania. Uzyskano następujące wyniki: pozorna energia aktywacji ługowania roztworem kwasu solnego Ea = 6,28 kJ mol-1, pozorny rząd reakcji n = 0,33.

3

Model przepływów materiałowych w pobieraniu próbek i analizie odpadów elektronicznych

Laubertova M., Malindzakova M., Rosova A., Trpcevska J.

Przemysł Chemiczny

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2016

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T. 95, nr 7

1390--1394

PL

Płytki z obwodami drukowanymi (2 kg) zostały wyjęte ze zużytych telefonów komórkowych (9,3 kg), rozdrobnione i zmielone na 2 frakcje ziarnowe poniżej 1,25 mm (młyn wibracyjny, 8 próbek) oraz poniżej 1,00 mm (młyn młotkowy, 8 próbek). Reprezentatywne próbki obu tych frakcji poddano analizie chemicznej na zawartość Cu i Ni metodą spektrometrii absorpcji atomowej. Wyniki oceniono stosując metodę wykresu skrzynkowego (box plot), aby usunąć dane odbiegające. Zawartość Cu była większa w próbce o mniejszych ziarnach niż w próbce o ziarnach większych (odpowiednio 18,14% i 13,71%) a zawartość Ni, przeciwnie, była większa w próbce o ziarnach większych (odpowiednio 1,76% i 2,44%). Zaproponowano procedurę przygotowania reprezentatywnej próbki płytek z obwodami drukowanymi do ich analizy chemicznej

EN

Printed circuit boards (2 kg) were recovered from waste mobile telephones (9.3 kg), disintegrated and grinded into 2 grain fractions up to 1.25 mm (vibration mill, 8 samples) and up to 1.00 mm (hammer mill, 8 samples). The representative samples of both fractions were analyzed for Cu and Ni contents by at. absorption spectroscopy. The results were assessed by box plot method to remove the deviated data. The Cu content was higher in the samples with smaller grains than that with coarser grains (18.14% and 13.71%, resp.) but the Ni content was higher in the samples with coarser grains than that with smaller grains (1.76% and 2.44%, resp.). A procedure for prepn. of a representative sample of the waste used for chem. anal. was proposed.

4

Properties of hypersonic sprayed nanostructured carbide coatings

Żórawski W., Trpcevska J.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2009

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Z. 13

446--450

EN

Nanostructured cermet coating was sprayed from agglomerated nanostructured WC12Co powder feedstock by means of hypersonic spray process (HVOF). Grains of tungsten carbide nanopowder were analyzed by scanning electron microscope (SEM) and transmission electron microscope (TEM). Investigations revealed that grains of powder consist of nanoparticles. Nanostructured sprayed coating was observed by SEM. A denser coating structure with higher hardness compared to conventional coating was observed. Dry abrasive rubber wheel tester was applied to estimate wear resistance. These tests show that nanostructured tungsten carbide have got better wear resistance.

5

Odporność na zacieranie powłok węglikowych natryskanych naddźwiękowo

Żórawski W., Trpcevska J.

Tribologia

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2007

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nr 3-4

453-463

PL

Powłoki natryskane naddźwiękowo są szeroko stosowane w różnych gałęziach przemysłu, jednak proces ich zużywania nie jest dostatecznie poznany. Dotyczy to zwłaszcza powłok pracujących na wysokoobciążonych częściach maszyn, gdzie podstawowym zagadnieniem jest trwałość i odporność na zatarcie. W artykule przedstawiono wyniki badań odporność na zatarcie powłok z WC-Co i Cr3C225%NiCr natryskanych HVOLF. Ocena odporności na zacieranie została przeprowadzona na testerze typu Falex w warunkach tarcia suchego. Największa odporność na zatarcie wykazała powłoka z WC-Co natryskana HVOLF posiadająca najbardziej jednorodną strukturę oraz największą twardość.

EN

Developed in early 80-s of last century HVOF sprayed coatings were result of looking for new solution in thermal spray technology directed on increasing of kinetic energy of powder grains. Nowadays HVOF spraying have found a lot of applications in different branches of industry [1, 2, 3, 4, 5, 8]. Properties of thermally sprayed coatings cause that the processes of wear are more complex than in the case of monolithic materials. The phenomenon, however, has not been fully explained [6]. Thermally sprayed elements are exposed to high loads, variable rotational speeds and high temperatures, which may result in undesirable under-lubrication or no lubrication at all. The problem refers mainly to such elements as, e.g. piston rings in combustion engines or synchroniser rings [3]. All forms of failure wear can be observed on the surfaces of mating elements. Intensive adhesive or thermal wear leads to the occurrence of local grafting and adhesion and, consequently, shorter life and scuffing. The interaction of ZrO2-MgO and Al2O340TiO2 coatings and cast iron under dry friction conditions is discussed in Ref. [7]. Ref. [9] deals with the development of scuffing for plasma sprayed ceramic and metal coatings interacting with bearing steel under dry friction conditions. The behaviour of oil-lubricated Cr3C2 coatings interacting with steel is described in [10]. Investigations on the problem of scuffing resistance of cylider bore are presented in paper [11]. Former investigations of properties of HVOLF sprayed coatings are presented in paper [12]. Two carbides produced by HC Stark tungsten carbide WC-Co (FST k-674.23) and chromium carbide Cr3C225%NiCr) (1375 VM), were used. For HVOLF spraying a JP-5000 (TAFA) gun was applied. Before the spraying, faces of cylindrical samples 12.7 x 10 made of steel 45 were grit blasted with 12 grade electrocorundum at a pressure of 0.5MPa. In this test a tribological tester, T-09 type Falex which has a friction pair with a pin and vee block association was applied to investigate scuffing resistance of thermally sprayed coatings under dry friction conditions. The microstructure of the sprayed coatings was analysed with a scanning microscope JOEL JSM-5400, whereas the element distribution with a microprobe ISIS 300 Oxford Instruments. The roughness of coatings was measured with a profilographometer Talysurf 4, whereas to study their hardness a Zwick 3210 hardness tester was used. The tests were carried out under dry friction conditions and had a comparative character. It was assumed that scuffing occurs when the pin clamping the rotating antisample is sheared. For each sprayed coating, the tests were repeated three times. HVOLF sprayed WC-Co coatings demonstrated better scuffing resistance (seizure observed at 1205 +, - 163 N), the most homogeneous structure and higher hardness (1218 HV0.1), respectively in the case of Cr3C225%NiCr scuffing resistance 1161 +, - 141 N and microhardness 945 HV0.1. The friction force oscillations are different in the case of WC-Co and Cr3C225%NiCr coatings. The oscillations for chromium carbide appear earlier and they were more intensive then in the case of tungsten carbide. Scuffing resistance of HVOLF sprayed WC-Co and Cr3C225%NiCr coatings was studied using a Falex type tester. It was established that HVOF sprayed wolfram carbide demonstrated the greatest resistance to scuffing, the most homogeneous structure and the highest hardness, whereas Cr3C225(Ni 20Cr) sprayed coating was characterised by the lower hardness. During the testing of the scuffing resistance of all interacting coatings, considerable oscillations of friction force could be observed. They were present also in the case of both coatings, but occurred earlier and were more intensive in the case of Cr3C225%NiCr coating.