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    Wyświetlanie 1-8 z 8
    Tytuł:
    Thiosulfate-copper-ammonia leaching of pure gold and pressure oxidized concentrate
    Autorzy:
    Porvali, A.
    Rintala, L.
    Aromaa, J.
    Kaartinen, T.
    Forsen, O.
    Lundstrom, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/110672.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold leaching
    thiosulfate
    quartz crystal microbalance
    Opis:
    In this research cyanide-free leaching of pure gold and pressure oxidized refractory gold concentrate by thiosulfate-copper-ammonia solutions were examined. A quartz crystal microbalance (QCM) was used to study gold leaching as a factorial series where the best gold leaching rate (2.987 mg/(cm2∙h)) was achieved with a solution consisting of 0.2 M (NH4)2S2O3, 1.2 M NH3, 0.01 M CuSO4 and 0.4 M Na2SO4. Temperature had the greatest effect on the gold leaching rate. An increase in thiosulfate concentration (0.1–0.2 M) increased gold dissolution. The combined effect of temperature and ammonia concentration had a statistically significant effect on the gold leaching rate at 0.1 M M2S2O3. Combination of applied potential and NH3:S2O3 ratio had a statistically significant effect on the gold leaching rate at 0.2 M M2S2O3. An increase in applied potential decreased the gold dissolution rate at low ammonia concentrations but increased it at high concentrations. A pressure oxidized gold concentrate was leached for 6 hours in the batch reactor leaching experiments. The effect of rotative velocity (1.26–1.56 m/s) and slurry density (10–30 wt%) was investigated at the following leaching parameters: 0.2 M Na2S2O3, 0.6 M NH3, 0.01 M CuSO4, 0.4 M Na2SO4. Lower slurry density (10 wt%) resulted in a higher Au leaching efficiency. An increase in the rotation rate did not have an effect on the final Au leaching recovery. The best Au leaching efficiency (89%) was achieved with 590 rpm mixing, 1.56 m/s rotative velocity and 10 wt% slurry density.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1079-1091
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pressure oxidation of pyrite-arsenopyrite refractory gold concentrate
    Autorzy:
    Rusanen, L.
    Aromaa, J.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/110051.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold ore
    hydrometallurgy
    leaching
    factorial design
    Opis:
    Refractory gold ores have poor gold recoveries with direct cyanide leaching. Typically the refractoriness is due to encapsulation of the gold particles inside the host mineral. To liberate gold for leaching the host mineral must be broken by mechanical or chemical means. The aim of this study was to study the effect of temperature, oxygen partial pressure and slurry density on pressure oxidation of pyrite-arsenopyrite gold concentrate. Batch oxidation tests in an autoclave were done using a factorial design. Different responses were measured and analysed to study effect of the three factors and oxidation kinet-ics. Generally, high slurry density required high temperature and oxygen partial pressure to reach com-plete oxidation. Oxidation kinetics at 225°C temperature, with 1050 kPa oxygen partial pressure and 15% slurry density was found to be fastest resulting in complete conversion of sulfides in 30 minutes. At 195°C, 700 kPa oxygen partial pressure and 10% slurry density, the oxidation kinetics for complete sul-fide conversion was about 60 minutes. Slurry densities above 10% had an adverse effect on the oxidation rate, when the temperature was below 225°C and oxygen partial pressure below 1050 kPa.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2013, 49, 1; 101-109
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Comparison of chemical and biological leaching of sulfide tailings
    Autorzy:
    Aromaa, J.
    Makinen, J.
    Vepsalainen, H.
    Kaartinen, T.
    Wahlstrom, M.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/110381.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    sulfide tailings
    chemical leaching
    bioleaching
    selectivity
    Opis:
    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.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2013, 49, 2; 607-620
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dissolution of gold with cyanide replacingreagents
    Autorzy:
    Aromaa, J.
    Rintala, L.
    Kahari, M.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/109410.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold leaching
    ammonium thiosulfate
    chloride
    thiourea
    thiocyanate
    Opis:
    Cyanide is used in the leaching phase of hydrometallurgical recovery of gold. The toxicity and environmental risks have created a need for safer alternatives. There is a vast amount of information about gold extraction and a selection has been collected and formalized to be used in a decision support tool. The tool Auric Advisor uses case-based reasoning (CBR) to provide process alternatives for the user queries. The aim of this paper is to study leaching of gold with cyanide replacing alternatives such as ammonium thiosulfate, chloride-hypochlorite, thiourea and thiocyanate to provide new cases for the tool. The behaviour of gold was examined with electrochemical tests and weight loss measurements a using quartz crystal microbalance (QCM) were used to determine the dissolution rate. Based on literature, the dissolution rate determined for cyanide solution was 2.5 mgcm-2h-1. Based on polarisation experiments and potential measurements, the ammonium thiosulfate system with cupric ion as oxidant was estimated to dissolve gold slower than cyanide. In the QCM tests the chloride-hypochlorite alternative showed highest dissolution rate of 8.6 mgcm-2h-1 at the redox potential of 900 mV vs. SHE. The thiocyanate system with ferric ion dissolved gold at a rate of 3.4 mgcm-2h-1 at the redox potential of 620 mV vs. SHE. Thiourea system with ferric ion showed the dissolution rate of 1.65 mg cm-2 h-1 at the redox potential of 450 mV vs. SHE. The results of the rapid tests were comparable with literature and were included in the case base of the Auric Advisor decision-support tool.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 1; 269-279
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Applicability of published experimental works as a knowledge source in recommendation of gold ore processing workflows
    Autorzy:
    Rintala, L.
    Aromaa, J.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/109780.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    gold ore
    leaching
    case-based reasoning
    process development
    Opis:
    The experimental work is the most time consuming and expensive part of the process design. A case-based reasoning (CBR) methodology can be used to assist in the process design. Auric Adviser is a CBR system under development for recommendation of gold ore processing workflows. In Auric Adviser the knowledge in gold ore processing is represented in two models. The first model holds the knowledge needed to recommend process chains already used in industry. The second knowledge model is intended to recommend the most efficient unit processes based on research results. The objective of this study was to analyse the information richness of journal articles and other publications concerning single process steps of gold extraction. The aim was to study the applicability of these publications as a source for the second Auric Adviser knowledge model. In this study, 25 publications concerning leaching of gold were analysed and information was extracted in a case base. The case base was taken as either a process or experimental description with clearly defined differences to other descriptions. In total, 218 cases that described results of gold leaching were extracted from the sources. The analysis of descriptions showed that the knowledge necessary for design the second Auric Adviser model can be elicited from journal articles and other publications concerning single process steps. The trends in the case description were that the gold content and process outcome were usually well described. Nevertheless, the information richness varied in descriptions of raw materials, experimental arrangements but the results were often missing details. The incompleteness of information causes challenges in the process comparison although it does not prevent the CBR system to work.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 2; 707-717
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Oxidative pressurized acid leaching of waste printed circuit boards
    Autorzy:
    Lundstrom, M.
    Seisko, S.
    Jascisak, J.
    Orac, D.
    Aromaa, J.
    Havlik, T.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/109824.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    batch leaching
    sulfuric acid
    copper
    tin
    gas formation
    Opis:
    The amount of waste printed circuit board (WPCB) increases continuously. There is an economic and environmental need to recover valuable metals from WPCBs. In this study, the applicability of oxidative pressurized acid leaching of WPCBs rich in copper and tin was investigated. The effect of leaching parameters such as temperature, partial oxygen pressure and chloride concentration on metal dissolution from WPCBs was studied in sulfuric acid media. It was shown that non-metallic elements present in WPCBs initiated gas formation, namely CO2 and CO, during oxidized pressure acid leach. Decomposition of plastic components already started at 90 °C with 1.5 MPa oxygen overpressure in the presence of 1 g/dm3 chlorides. Gas formation was shown to have a negative impact on the process since copper extraction was reduced to 27% compared to 80-90% extraction achieved from anode slimes used as a reference material. It was suggested that gas formation related to plastic components could have a severe impact on metal yields. The highest dissolution of tin equal to 36% was achieved at room temperature. It was found that higher temperature promoted tin hydrolysis.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2017, 53, 2; 781-792
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alkaline leaching of zinc from argon oxygen decarbonization dust from stainless steel production
    Autorzy:
    Stefanova, A.
    Aromaa, J.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/110385.pdf
    Data publikacji:
    2013
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    AOD dust
    stainless steel
    zinc
    leaching
    sodium hydroxide
    Opis:
    Stainless steel production generates solid wastes such as dust and sludge that are considered as harmful in most industrial countries. Today dusts are recycled in separate treatment plants as these dusts contain valuable metals such as alloying elements. A direct recycling of dust back to steel production is hindered due to the presence of elements, especially zinc, that cause operational difficulties in the stain-less steel making process. In this paper two different stainless steel converter argon oxygen decarboniza-tion dusts (AOD1 and AOD2), from Outokumpu Stainless (Tornio, Finland), were leached using NaOH solutions. The purpose was to selectively leach zinc out from the dusts and to find factors that affected most dissolution of zinc. The dust samples were leached under atmospheric pressure and the factors tested were temperature, sodium hydroxide concentration, liquid to solid ratio (L/S), stirring rate and oxygen or nitrogen gas bubbling. All the studied factors had statistically significant effect on the dissolution of zinc. The maximum zinc extraction was achieved at 95°C, with 8M NaOH solution, stirring rate of 400 rpm and L/S ratio of 30 and was around 80% for AOD1 dust and around 50% for AOD2 dust. Difference in maximum zinc extraction arose from the mineralogical differences of the dusts. Zinc was leached selec-tively. Among alloying elements only molybdenum was leached and practically no iron, chromium and nickel were dissolved.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2013, 49, 1; 27-46
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alkaline leaching of zinc from stainless steel electric arc furnace dusts
    Autorzy:
    Stefanova, A.
    Aromaa, J.
    Forsen, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/110674.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    electric arc furnace dust
    EAF
    stainless steel
    zinc
    leaching
    sodium hydroxide
    Opis:
    Stainless steel production generates dust and sludge that are considered as a harmful waste. These dusts contain also valuable metals but extraction and recovery of valuables is difficult due their complex composition. Zinc is the most troublesome element in the dust and it hinders direct recycling of dust back into furnaces. In this paper two different stainless steel electric arc furnace dusts (EAF1 and EAF2) from Outokumpu Stainless (Tornio, Finland), were leached using NaOH solutions. The purpose was to selectively leach out zinc from the dusts and to find factors that affected most dissolution of zinc. From all leaching factors temperature, agitation speed and NaOH concentration were found to be statistically strongly significant, whereas a liquid-to-solid ratio and bubbling gas were only somehow significant. Two experiments from the test series gave clearly higher zinc extraction, that is around 60% for EAF1 and 30% for EAF2. For those experiments, a strong 8 M NaOH solution with the high temperature and agitation speed was used but bubbling gas and liquid-to-solid ratio changed. Zinc was leached selectively and practically no iron, chromium and nickel dissolved.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2015, 51, 1; 293-302
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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