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1

A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid

Arslan Volkan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 3

97--111

EN

Clay is widely used in a number of industries due to its special properties like fine particle size, brightness and whiteness, chemical inertness, platy structure, etc. In this study, the general characteristics of clays have been investigated by XRF, XRD, FT-IR, TG-DTA and SEM. The presence of iron as an impurity decreases its commercial value due to giving unwanted colors to clay mineral. Therefore, the dissolution capacity of clay ore was investigated by oxalic acid leaching. Under optimized leaching conditions (0.8 M oxalic acid concentration, 85°C reaction temperature, 1.75 ambient pH, 106+75 µm particle size, 15% w/v solids concentration and 150 min. leaching time) with 250 rpm stirring, 83.90% of Fe2O3 was removed. The amount of iron oxide, the main impurity in the clay, has been reduced from 2.70 to 0.40%. The iron dissolution kinetics was mainly controlled by internal diffusion control of shrinking core model and activation energy, Ea, of 26.29 kJ/mol was obtained for the process. The results also showed that the studied clays have adequate characteristics for ceramics industry, earthenware and porcelain production.

2

Comparison of the Effectiveness of Biological and Chemical Leaching of Copper, Nickel and Zinc from Circuit Boards

Andrzejewska-Górecka Dorota Anna, Poniatowska Agnieszka, Macherzyński Bartłomiej, Wojewódka Dominik, Wszelaka-Rylik Małgorzata Edyta

Journal of Ecological Engineering

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2019

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Vol. 20, nr 9

62--69

EN

The progress of civilization brings with it the development of advanced technologies and increased demand for electric and electronic equipment. That directly influences the increase of produced e-waste, called Waste of Electrical and Electronic Equipment (WEEE). Due to the fact that deficit and critical metals are running out throughout the World, and due to increased demand for those metals, their alternative source and recovery methods have to be found. As an alternative biotechnological methods can be used. The advantage of biological methods over chemical processes is its selectivity in regard to different metal groups, simplicity of technological process, economic effectivity (lower energy expenditure) and lack of negative impact on environment. The aim of this work was to compare the effectiveness of biological and chemical leaching of copper (Cu), nickel (Ni) and zinc (Zn) from circuit boards (PCBs).The experiment was conducted in variants which included factors such as temperature (24°C and 37°C) and speed of mixing. In case of all metals higher effectiveness was achieved in variants conducted in the temperature of 24°C and faster mixing than in temperature of 37°C and slower mixing. In case of cooper and zinc better results of metal removal were achieved in bioleaching variant. In case of nickel faster result of metal removal were achieved in chemical leaching, but at the end of the experiment the effectivity of chemical leaching and biological leaching was similar. The maximum efficiency of cooper, nickel and zinc release was adequately 100%, 90%, 65%.

3

Removal of sulfur and phosphorous from iron ore concentrate by leaching

Rezvani Pour H., Mostafavi A., Shams Pur T., Ebadi Pour G., Haji Zadeh Omran A.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

845--854

EN

Iron ore having high-sulfur content causes problems in the concentrate production, pelletizing, and steel-making processes and environmental issues such as sulfur dioxide emission during the concentrate pelletizing process, and effect on steel quality. The current study was focused on the removal of sulfur from iron ore concentrate using chemical leaching technique. Magnetite iron ore concentrate was chosen for this purpose. The results obtained from the study showed that more than 90% of the total sulfur content was removed from the iron ore concentrate by the chemical leaching. Effects of several parameters, including temperature, stirring speed, particle size, and use of organic solvent on the sulfur removal was investigated by a series of experimental conditions. After optimizing the experimental conditions, it was demonstrated that in addition to sulfur, more than 80% of phosphorus, another important impurity, was also removed from the iron ore concentrate. In addition, one of the major advantages of our proposed method was the transformation of mineral pyrites to useful byproducts such as elemental sulfur.

4

Comparison of chemical and biological leaching of sulfide tailings

Aromaa J., Makinen J., Vepsalainen H., Kaartinen T., Wahlstrom M., Forsen O.

Physicochemical Problems of Mineral Processing

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2013

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Vol. 49, iss. 2

607--620

EN

Sulphidic tailings from Finnish Hitura nickel mine and Pyhäsalmi multi-metal mine were leached using sulphuric acid and bioleached. The aim was to recover minor amounts of valuable Cu, Ni, Zn and Mn. Both tailings consisted mainly of iron and magnesium-containing minerals and acid neutralizing minerals. The solution after chemical leaching tests contained mostly iron and magnesium, in Hitura up to 11 g/dm3 Fe and 38 g/dm3 Mg while in Pyhäsalmi 8–9 g/dm3 Fe and 4 g/dm3 Mg. Amount of these metals was 20–100-fold larger than amount of valuable metals, which were typically 100-300 mg/dm3. Problems in chemical leaching were high consumption of acid and poor selectivity. Bioleaching using iron and sulphur oxidizing bacteria was more selective towards the valuable metals. Both in leaching and bioleaching the high concentration of iron and magnesium in solution will make metals recovery challenging.

5

Odzysk metali ze zużytych katalizatorów uwodorniania stosowanych w przemyśle petrochemicznym

Mulak W., Szymczycha-Madeja A., Miazga B.

Rudy i Metale Nieżelazne

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2007

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R. 52, nr 8

482-490

PL

Przedstawiono przegląd wyników badań nad odzyskiem metali ze zużytych katalizatorów uwodorniania stosowanych w procesach rafineryjnych. Uwagę skoncentrowano na procesach hydropirometalurgicznych i hydrometalurgicznych z uwzględnieniem bioługowania, ługowania elektrochemicznego oraz ługowania w mediach w stanie nadkrytycznym. W procesach hydropirometalurgicznych etap ługowania poprzedzony jest prażeniem chlorującym (z CI2, NaCl, NH4CI), kalcynującym (Na2CO3 lub Na2O), lub wypalaniem zużytego katalizatora. Wykazano, że prażenie chlorujące w mieszaninie CI2 + N2 + CO jest wysoce efektywne i pozwala na odzysk metali z katalizatora w ilości: 99 % Mo, 74 % V, 75 % Co oraz 85 % Ni. W przypadku Mo porównywalne wyniki (97 %) można otrzymać stosując kalcynację z dodatkiem Na2COj w 450 °C i czasie 2 godzin i następnie ługowanie NaOH. W procesach hydrometalurgicznych do ługowania stosuje się szereg reagentów nieorganicznych i organicznych lub ich kombinacji. Stosowano takie reagenty, jak: NaOH, Na2CO3, H2SO4, NH3xH2O, H2C2O4 z dodatkiem utleniaczy (Fe3+, H2O2). Najwyższe stopnie wyługowania Mo (90 %) i V (94 %) uzyskano w roztworze 0,5 M H2C2O4 z dodatkiem 3,0 M H2O2 w czasie 4 godzin, w temperaturze 50 °C. Przedstawiono także wyniki lugowań ciśnieniowych w roztworach kwaśnych i alkalicznych. W omówionych procesach bioługowania zużytych katalizatorów stosowano grzyby Aspergillus niger w 2,0 M roztworze H2C2O4 w czasie 30 dni, uzyskano w roztworze 82,3 % Mo, 78,5 % Ni oraz 65,2 % Al. Metoda elektrochemicznego roztwarzania zużytych katalizatorów w przestrzeni anodowej elektrolizera z użyciem jonów Ce4+ jako utleniacza pozwala na całkowite roztworzenie zużytego katalizatora w roztworze zawierającym 0,5 M jonów Ce4+ w 2,0 M HNO3 w temperaturze 110 °C w czasie 14 godzin.

EN

Recycling of spent catalysts has become recently an unavoidable task not only due to catalysts costs but also in order to prevent the environmental pollution. The results of studies on the recovery of metals from spent hydroprocessing catalysts used in the refinery processes have been reviewed. The following processes have been discussed: hydropyrometallurgical, hydrometallurgical, biohydrometallurgical, leaching by supercritical media, as well as electrochemicał dissolution. The hydropyrometallurgical processes reąuire pretreatment of roasting with CI2, NaCl and NH4Cl, calcination with Na2CO3 and Na2O or combustion of spent catalysts followed by water leaching. Generally, chlorination has disadvantages sińce it is connected with corrosion and gas handling problems. It was found that the chlorination with CI2+N2+CO turns to be highly effective and leads to recovery of 99 % Mo, 74 %V, 75 % Co, and 85 % Ni. The comparable results of Mo leaching (97 %) were achieved using the calcination with Na2CO3 at temperaturę 450 °C during 2 hours followed by NaOH leaching. In turn, the hydrometallurgical processes involve leaching with inorganic and organie agents or their combustion. Many reagents such as: NaOH, Na2CO3, H2SO4, NH3xH2O, H2C2O4 in the presence of oxidizing agents (Fe3+, H2O2) were tested. The most promising results have been achieved for the chelating agents being able to form soluble metal complexes. The highest leaching efficiency of Mo (90 %) and V (94 %) were reached after 4 hours leaching in the solution containing 0.5 M H2C2O4 and 3.0 M H2O2- The alkali and acid leaching processes under high pressure have been also presented. Comparing to the conventional techniąues the biohydrometallurgical methods seem to be more attractive for the recovery of metals from spent catalysts. In fact they are simpler, cheaper and more environmentally friendly. In bioleaching one of the most widely used fungus is Aspergillus niger. Its application has advantages over bacterial leaching sińce this particularfungus reveals the ability of metal leaching under higher pH conditions and gives thefaster leaching rate. Bioleaching results of the spent refinery catalysts with Aspergillus niger fungus in 0.2 M H2C2O4 solution showed that 82.3 % Mo, 78.5 % Ni and 65.2 % Al were extracted after 30 days. Another techniąue is the supercritical fluid extraction may provide a clean and efficient method for removing metal species from contaminated solid materials. Conceptually, such a process would entail loading a spent catalyst into a pressure vessel and leaching it with supercritical CO2 containing 5 % methanol and a smali ąuantity ofa chelating reagent. In particularly, the recovery o noble metals from spent catalysts is possible by supercritical water leaching at 400 °C and 250 atm (Aqua Cat process). Finally, the results of experiments investigating the electrochemical dissolution showed that 0.5 M Ce4+ solution as an oxidant in 2.0 M HNO3 at 110 °C would completely dissolve a spent hydrosulphurization catalyst (HDS) in 14 hours.

6

Możliwości podwyższenia jakości koncentratu miedziowego metodą hydrometalurgiczną

Konopka E., Małysa E.

Gospodarka Surowcami Mineralnymi

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2006

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T. 22, z. 3

95-110

PL

W polimetalicznym złożu rud miedzi występuje m.in. ołów, który w procesie wzbogacania flotacyjnego wraz z miedzią przechodzi do koncentratu. W pirometalurgii miedzi jej koncentrat powinien zawierać maksymalnie tylko 1% Pb, gdy tymczasem ten niepożądany składnik może występować w podwyższonej ilości nawet powyżej 2%. Celem przeprowadzonych badań było osiągnięcie maksymalnego uzysku ołowiu na drodze hydrometalurgicznej, przy zagwarantowaniu możliwie niskiej energochłonności procesu, nawet kosztem wydłużenia jego czasu. Stwierdzono możliwość obniżenia zawartości ołowiu w koncentracie nawet do wartości 0,13% Pb, jednak za racjonalny można uznać poziom 0,8—0,6% Pb, możliwy do osiągnięcia w ciągu jednej doby. Dokonana została charakterystyka metalonośności octanowych roztworów ługujących oraz wykazano racjonalny sposób wykorzystania ich pojemności ekstrakcyjnej.

EN

In polymetalic deposits of the copper ore there is also contained lead, which during flotation process is concentrated together with copper in the froth product. In pyrometallurgical processing of the copper concentrates it is a requirement that the lead contents should not exceed 1%, while the contents of this undesired component (lead) are often even above 2%. The carried out studies aimed at obtaining maximum recovery of lead, from the copper concentrates by hydrometallurgical method, at as low as possible energy consumption even at the expense of the process time prolongation. It was found that the lead contents in the concentrate could be lowered by the hydrometallurgical method applied even to a value of 0.13% Pb. However, a level of 0.8—0.6% Pb contents was found to be rational and possible to be reached during twenty-four hours processing. A characteristics of metal contents in acetate leaching solutions was performed and a rational way of utilization of their extractive capacity was evaluated.