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Sandström, Åke
Publications (10 of 68) Show all publications
Strandkvist, I., Sandström, Å. & Engström, F. (2017). Effect of FeO/MgO Ratio on Dissolution and Leaching of Magnesiowüstite. Steel Research International, 88(6), Article ID e201600322.
Open this publication in new window or tab >>Effect of FeO/MgO Ratio on Dissolution and Leaching of Magnesiowüstite
2017 (English)In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 88, no 6, article id e201600322Article in journal (Refereed) Published
Abstract [en]

If slag is to be used as construction material, the leaching of some elements, such as chromium must be limited. The leaching of slag depends on the leaching properties of the minerals in the slag. However, the leaching/dissolution properties of individual slag minerals are usually not studied. One common slag mineral that can contribute to the leaching of chromium is magnesiowüstite. The object of this study is to determine whether magnesiowüstite can be modified to avoid chromium leaching. Magnesiowüstite samples with different FeO/MgO ratios with and without chromium content are manufactured. The dissolution is evaluated at pH 7 and 10 using the magnesiowüstite samples without chromium, at size fraction 20–38 μm, by measuring the acid consumption required to maintain constant pH level. The magnesiowüstite samples with chromium content are leached at pH 10; the leachate is analyzed for chromium. The results are unanimous, with increasing FeO content the dissolution of magnesiowüstite and leaching of chromium decrease. At pH 10 the magnesiowüstite, with ≥60 wt% FeO show no sign of dissolution and no chromium leaching could be detected with ≥70 wt% FeO. The results prove that the FeO content can stabilize magnesiowüstite and, thereby, prevent chromium leaching

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-61445 (URN)10.1002/srin.201600322 (DOI)000404545600006 ()2-s2.0-85020044828 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-06-02 (andbra)

Available from: 2017-01-16 Created: 2017-01-16 Last updated: 2018-07-10Bibliographically approved
Khoshkhoo, M., Dopson, M., Engström, F. & Sandström, Å. (2017). New insights into the influence of redox potential on chalcopyrite leaching behaviour. Minerals Engineering, 100, 9-16
Open this publication in new window or tab >>New insights into the influence of redox potential on chalcopyrite leaching behaviour
2017 (English)In: Minerals Engineering, ISSN 0892-6875, E-ISSN 1872-9444, Vol. 100, p. 9-16Article in journal (Refereed) Published
Abstract [en]

Chalcopyrite (CuFeS2) is the most economically important and most refractory copper mineral when treated in conventional sulphate media leaching systems. In this study, the effect of solution redox potential on leaching of a pure and a pyritic chalcopyrite concentrate was investigated using concentrates with fresh and aged surfaces. In experiments using concentrates with fresh surfaces, the response to redox potential depended on the presence of pyrite: fresh pyritic concentrate leached more effectively at low redox potential (in agreement with reductive leaching mechanisms), while the leaching efficiencies from fresh pure concentrate were similar at high and low redox potentials. The data suggested that the reductive leaching mechanism does not necessarily result in higher and faster recoveries in the absence of the galvanic interaction induced by the presence of pyrite. It was also found that exposure of chalcopyrite to atmospheric oxidation prior to leaching (ageing) had an effect on leaching behaviour in response to redox potential: copper recoveries in leaching of aged concentrates were higher at high redox potentials. This behaviour was attributed to the presence of iron–oxyhydroxides on the surface of aged concentrates. Based on the data from this investigation and previous surface studies, it is proposed that iron–oxyhydroxides play an important role in triggering the hindered dissolution of chalcopyrite.

Place, publisher, year, edition, pages
Elsevier, 2017
National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-59595 (URN)10.1016/j.mineng.2016.10.003 (DOI)000390508900002 ()2-s2.0-84991660408 (Scopus ID)
Note

Validerad; 2016; Nivå 2; 2016-10-10 (andbra)

Available from: 2016-10-10 Created: 2016-10-10 Last updated: 2018-09-13Bibliographically approved
Johansson, Ö., Pamidi, T., Khoshkhoo, M. & Sandström, Å. (2017). Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation. Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Sustainable and energy efficient leaching of tungsten(W) by ultrasound controlled cavitation
2017 (English)Report (Other academic)
Abstract [en]

The project aims to use ultrasound controlled cavitation to achieve a more energy efficient leaching process. Locally, collapsing cavitation bubbles cause an extremely high pressure, shock waves and high temperature, which provide an opportunity to perform the leaching process at a much lower temperature than in an autoclave (20 bar overpressure and 220 ° C). The results show that the method works, but that a higher static pressure and thus temperatures are necessary to achieve a leaching recovery rate corresponding to today's autoclave technology. Another process parameter of importance is flow control and the initiation of cavitation bubbles that occur through a geometrically optimized nozzle (orifice plate). Numerical and experimental adaptation of the developed reactor with respect to the leaching conditions (Sodium hydroxide and Scheelite concentrate), required more time than expected. Best test results show that an energy supplement with ultrasonic controlled cavitation of 104 kWh / kg increases the leaching recovery by 21%. The leaching reagent temperature 60° C was determined regarding available reference data and was thought to be close to optimum for intensive cavitation in atmospheric pressure. Optimum temperature relates to the leaching reagent, vaporization temperature, density, boiling point, surface tension, and viscosity. Generally, for leaching is that higher temperatures are required to increase the chemical reaction rate (requires overpressure). The modified reactor principle provides stable results and is possible to scale up. Higher cavitation intensity for shorter finishing time and higher recovery rate require advanced flow induction, multiple excitation frequencies adapted to the optimized reactor geometry, as well as optimal process pressure and temperature.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. p. 20
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
Ultrasound, Cavitation; Leaching, Scheelite, Vibro acoustic optimization
National Category
Mineral and Mine Engineering Fluid Mechanics and Acoustics Metallurgy and Metallic Materials
Research subject
Engineering Acoustics; Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-66286 (URN)978-91-7790-160-0 (ISBN)
Projects
Vinnova SIP-Strim
Funder
VINNOVA, 2016-02620VINNOVA
Available from: 2017-10-27 Created: 2017-10-27 Last updated: 2018-06-05Bibliographically approved
Sandström, Å. (2016). Mechanochemical Treatment in Metallurgy: An overview (ed.). Paper presented at Conference in Minerals Engineering 2016 : 02/02/2016 - 03/02/2016. Paper presented at Conference in Minerals Engineering 2016 : 02/02/2016 - 03/02/2016.
Open this publication in new window or tab >>Mechanochemical Treatment in Metallurgy: An overview
2016 (English)Conference paper, Oral presentation only (Other academic)
Abstract [en]

This review paper deals with the application of mechanochemical treatment with the aim to recover metals from both primary and secondary resources. For primary resources, the focus is on minerals like chalcopyrite, tetrahedrite and scheelite i.e. minerals with high activation energies where leaching in autoclaves at high temperature is needed to have acceptable leaching kinetics. In these cases, a mechanochemical treatment might enable leaching to be performed under atmospheric pressures. For secondary resources, emphasis has been on recycling of elements regarded as critical by the EU due to limited availability or high risk of future supply within the union.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-34980 (URN)95066e07-1702-4c3f-8c79-fb21b13274b9 (Local ID)95066e07-1702-4c3f-8c79-fb21b13274b9 (Archive number)95066e07-1702-4c3f-8c79-fb21b13274b9 (OAI)
Conference
Conference in Minerals Engineering 2016 : 02/02/2016 - 03/02/2016
Note
Godkänd; 2016; 20160623 (andbra)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-25Bibliographically approved
Alakangas, L., Sandström, Å., Rosenkranz, J., Martinsson, O. & Hällström, L. (2016). Project: Improve Resource Efficiency and Minimize Environmental Footprint. Paper presented at .
Open this publication in new window or tab >>Project: Improve Resource Efficiency and Minimize Environmental Footprint
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2016 (English)Other (Other (popular science, discussion, etc.))
Abstract [en]

The REMinE project is organized in five work packages that comprise: detailedcharacterization and risk assessment of the mine wastes selected (WP2), identification of new processing methods for mine waste (WP3), characterization and risk assessment of the remaining residuals (WP4), outlining business opportunities and environmental impact in a conceptual model for sustainable mining (WP5). The project comprises case studies of historical mine wastes from three different European countries, namely Portugal, Romania and Sweden. The interdisciplinary research collaboration in this project is innovative in the sense that separation of minerals and extraction of metals not only are basedon technical and economic gain but also considers the environmental perspective.

Keywords
historical mines, mining environment
National Category
Geochemistry Metallurgy and Metallic Materials Geology
Research subject
Tillämpad geokemi; Process Metallurgy; Mineral Processing; Ore Geology
Identifiers
urn:nbn:se:ltu:diva-35989 (URN)0fdbbf5b-f258-4656-9d55-a2ae3e19361a (Local ID)0fdbbf5b-f258-4656-9d55-a2ae3e19361a (Archive number)0fdbbf5b-f258-4656-9d55-a2ae3e19361a (OAI)
Note

Status: Ongoing; Period: 30/11/2015 → 31/03/2019

Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-05-21Bibliographically approved
Wikedzi, A., Sandström, Å. & Awe, S. A. (2016). Recovery of antimony compounds from alkaline sulphide leachates (ed.). International Journal of Mineral Processing, 152, 26-35
Open this publication in new window or tab >>Recovery of antimony compounds from alkaline sulphide leachates
2016 (English)In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 152, p. 26-35Article in journal (Refereed) Published
Abstract [en]

In copper metallurgy, antimony impurity usually forms alloys and compounds with the transition metals to make up the basic building blocks of a speiss phase. This speiss phase is generally rich in copper and precious metals which are desirable to recycle and recover at the smelter. The presence of this impurity unfortunately creates a build-up of this metal in the copper circuit, leading to problems during copper refining processes. Therefore, a removal or reduction of the antimony impurity to an acceptable level is a necessary step before the speiss can be recycled at the smelter for the recovery of its valuable metals. A lead oxide slag, which was obtained after speiss had gone through a special pyrometallurgical process, was leached in alkaline sulphide solution to selectively dissolve its antimony content. Furthermore, the pregnant sulphide leachate was purified by precipitation and crystallization techniques to recover antimony as sodium thioantimonate and sodium hydroxyl antimonate using synthetic Na2S-NaOH-Sb2S3 solution. The leaching results indicate that the highest amount of antimony and arsenic extracted from the material after 24 h at 100oC and reagent concentration of 30 g/L NaOH + 30 g/L S2- was 83% and 90%, respectively. In the precipitation process, addition of hydrogen peroxide to the alkaline sulphide leachate prompts the precipitation of antimony as NaSb(OH)6. The result also implies that less than 100% of stoichiometric hydrogen peroxide is required to completely oxidize the total amounts of both Sb3+ and S2- in the solution to quantitatively precipitate more than 90% of the antimony in solution. The influence of catalytic agents and temperature on the process was not clearly reflected in this investigation due to the exothermic reaction with hydrogen peroxide. Moreover, addition of elemental sulphur to the sulphide leachate also influences the precipitation of antimony as sodium thioantimonate.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-5154 (URN)10.1016/j.minpro.2016.05.006 (DOI)000378954200004 ()2-s2.0-84969780233 (Scopus ID)32e94f84-c623-4af9-84a0-243bd1dd1930 (Local ID)32e94f84-c623-4af9-84a0-243bd1dd1930 (Archive number)32e94f84-c623-4af9-84a0-243bd1dd1930 (OAI)
Note

Validerad; 2016; Nivå 2; 20150817 (samawe)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sand, A., Rosenkranz, J., Lund, C., Sandström, Å. & Samuelsson, C. (2015). Education Related to Mineral Raw Materials in the European Union: D3.3 Final Report on Skill Shortages and Means of Addressing Them (ed.). Paper presented at .
Open this publication in new window or tab >>Education Related to Mineral Raw Materials in the European Union: D3.3 Final Report on Skill Shortages and Means of Addressing Them
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2015 (English)Report (Other (popular science, discussion, etc.))
Publisher
p. 60
National Category
Metallurgy and Metallic Materials
Research subject
Mineral Processing; Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-22164 (URN)1cb2a1a7-a088-41b1-b5a4-db9fbee96321 (Local ID)1cb2a1a7-a088-41b1-b5a4-db9fbee96321 (Archive number)1cb2a1a7-a088-41b1-b5a4-db9fbee96321 (OAI)
Note
Godkänd; 2015; 20150623 (andsan)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-01-19Bibliographically approved
Rodríguez, N. P., Khoshkhoo, M., Sandström, Å., Rodushkin, I., Alakangas, L. & Öhlander, B. (2015). Isotopic signature of Cu and Fe during bioleaching and electrochemical leaching of a chalcopyrite concentrate (ed.). Paper presented at . International Journal of Mineral Processing, 134, 58-65
Open this publication in new window or tab >>Isotopic signature of Cu and Fe during bioleaching and electrochemical leaching of a chalcopyrite concentrate
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2015 (English)In: International Journal of Mineral Processing, ISSN 0301-7516, E-ISSN 1879-3525, Vol. 134, p. 58-65Article in journal (Refereed) Published
Abstract [en]

Bioleaching is an important process in metallurgy and in environmental sciences, either for the acquisition of metals or for the formation of acid rock drainage. In this study the implications of the processes during bioleaching of a pyritic chalcopyrite concentrate were analysed regarding its Cu and Fe isotope fractionation. The development of the redox potential during the bioleaching experiment was then simulated in an electrochemical cell in absence of microorganisms to investigate the effect of microbial activity on the Cu and Fe isotope fractionations. The leaching experiments were performed for 28 days at 45 °C with a solid content of 2.5% (w/v) at pH 1.5. It was found that Cu dissolution efficiency was similar in both experiments and the leaching curves were linear with no sign of passivation due to presence of pyrite. The heavy Cu isotope (δ65Cu) was leached more easily and as a result the leachate was enriched with the heavy Cu isotope at the beginning of both experiments and as the leaching progressed δ65Cu values in the leachate became similar to the ones of the chalcopyrite concentrate, confirming an equilibrium fractionation happening in a closed system. There was no distinct difference in the Cu and Fe isotope fractionations in absence and presence of microorganisms. Finally based on Cu and Fe isotope signatures, a simplified method is suggested for the estimation of the leaching extent during the oxidisation of sulphide materials in natural systems.

National Category
Metallurgy and Metallic Materials Geochemistry
Research subject
Process Metallurgy; Applied Geology
Identifiers
urn:nbn:se:ltu:diva-5240 (URN)10.1016/j.minpro.2014.11.010 (DOI)000348960600008 ()2-s2.0-84924082946 (Scopus ID)348dc9fd-2b99-4601-aa07-7e40c905974c (Local ID)348dc9fd-2b99-4601-aa07-7e40c905974c (Archive number)348dc9fd-2b99-4601-aa07-7e40c905974c (OAI)
Note
Validerad; 2014; Nivå 2; 20141128 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Sany, S. M., Dopson, M. & Sandström, Å. (2015). Role of Microbial Activity in Bioleaching of a Pyritic and a Pure Chalcopyrite Concentrate (ed.). Paper presented at International Biohydrometallurgy Symposium : 05/10/2015 - 09/10/2015. Advanced Materials Research, 1130, 209-213
Open this publication in new window or tab >>Role of Microbial Activity in Bioleaching of a Pyritic and a Pure Chalcopyrite Concentrate
2015 (English)In: Advanced Materials Research, ISSN 1022-6680, E-ISSN 1662-8985, Vol. 1130, p. 209-213Article in journal (Refereed) Published
Abstract [en]

Leaching of a pyritic and a pure chalcopyrite concentrate was carried out in stirred tank reactors in the absence and presence of a mixed culture of moderately thermophilic microorganisms at 45°C and pH 1.5. To study the effect of microbial activity on copper dissolution, the abiotic experiments were performed under accurately controlled redox potential conditions to reproduce the same oxidising conditions recorded during the bioleaching experiments. X-ray photoelectron spectrometry (XPS) was used to study the surface of chalcopyrite chips leached for different durations. The results showed that the microorganisms in cases of both concentrates did not have any effect in the copper leaching efficiency other than oxidation of ferrous to ferric ions. Biooxidation of elemental sulphur did not improve the leaching efficiency and bulk and surface jarosite had no negative effect on dissolution. A composite layer composed of mainly elemental sulphur and iron-oxy-hydroxide was found to be responsible for the hindered dissolution.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-29876 (URN)10.4028/www.scientific.net/AMR.1130.209 (DOI)37e3ac66-a9ed-4a31-b501-c3c853fdca62 (Local ID)37e3ac66-a9ed-4a31-b501-c3c853fdca62 (Archive number)37e3ac66-a9ed-4a31-b501-c3c853fdca62 (OAI)
Conference
International Biohydrometallurgy Symposium : 05/10/2015 - 09/10/2015
Note
Validerad; 2016; Nivå 1; 20151029 (seykos); Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2017-11-30Bibliographically approved
Khoshkhoo, M., Dopson, M., Shchukarev, A. & Sandström, Å. (2014). Chalcopyrite leaching and bioleaching: An X-ray photoelectron spectroscopic (XPS) investigation on the nature of hindered dissolution (ed.). Paper presented at . Hydrometallurgy, 149, 220-227
Open this publication in new window or tab >>Chalcopyrite leaching and bioleaching: An X-ray photoelectron spectroscopic (XPS) investigation on the nature of hindered dissolution
2014 (English)In: Hydrometallurgy, ISSN 0304-386X, E-ISSN 1879-1158, Vol. 149, p. 220-227Article in journal (Refereed) Published
Abstract [en]

Chalcopyrite (CuFeS2) is both the most economically important and the most difficult copper mineral to (bio)leach. The main reason for the slow rate of chalcopyrite dissolution is the formation of a layer on the surface of the mineral that hinders dissolution, termed “passivation”. The nature of this layer is still under debate. In this work, the role of bacterial activity was examined on the leaching efficiency of chalcopyrite by mimicking the redox potential conditions during moderately thermophilic bioleaching of a pure chalcopyrite concentrate in an abiotic experiment using chemical/electrochemical methods. The results showed that the copper recoveries were equal in the presence and absence of the mixed culture. It was found that the presence of bulk jarosite and elemental sulphur in the abiotic experiment did not hamper the copper dissolution compared to the bioleaching experiment. The leaching curves had no sign of passivation, rather that they indicated a hindered dissolution. XPS measurements carried out on massive chalcopyrite samples leached in the bioleaching and abiotic experiments revealed that common phases on the surface of the samples leached for different durations of time were elemental sulphur and iron-oxyhydroxides. The elemental sulphur on the surface of the samples was rigidly bound in a way that it did not sublimate in the ultra-high vacuum environment of the XPS spectrometer at room temperature. Jarosite was observed in only one sample from the abiotic experiment but no correlation between its presence and the hindered leaching behaviour could be made. In conclusion, a multi-component surface layer consisting of mainly elemental sulphur and iron-oxyhydroxides were considered to be responsible for the hindered dissolution.

National Category
Metallurgy and Metallic Materials
Research subject
Process Metallurgy
Identifiers
urn:nbn:se:ltu:diva-8464 (URN)10.1016/j.hydromet.2014.08.012 (DOI)000344204400026 ()2-s2.0-84907266299 (Scopus ID)6fa0719d-cd2a-4a50-a13c-5af5467c1611 (Local ID)6fa0719d-cd2a-4a50-a13c-5af5467c1611 (Archive number)6fa0719d-cd2a-4a50-a13c-5af5467c1611 (OAI)
Note
Validerad; 2014; 20140904 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
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