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- Cunha, Maria Lucelinda, et al.
(författare)
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Leaching behaviour of industrial oxidic by-products : possibilities to use as neutralisation agent in bioleaching
- 2008
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Ingår i: Advanced Materials Forum IV. - Stafa-Zurich : Trans Tech Publications Inc.. ; , s. 748-752
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Konferensbidrag (refereegranskat)abstract
- In this study chemical leaching with sulphuric acid has been performed on 10 selected oxidic by-products in order to determine their neutralising capacity. The ultimate aim with this work is to replace the lime or limestone normally used in bioleaching operations to maintain pH at 1.5, the optimum pH-level for bioleaching microorganisms, with oxidic by-products. The investigated by-products includes three ashes from combustion for energy production, five slag samples from ore and scrap based steelmaking, an EAF dust and mesa lime from a paper and pulp industry, slaked lime (Ca(OH)2) was used as reference material. The neutralising potential of the by-products were evaluated by leaching them with sulphuric acid and comparing the amount of acid needed to that of the reference. Most of the by-products examined had good neutralisation potential and some had even higher capacities than Ca(OH)2. Neutralisation kinetics were lower for some slag products due to slow dissolution of some of the silicates present, but kinetics are considered good enough since stirred tank bioleaching is a relatively slow process. Zinc recoveries from the zinc containing materials were high, which thus is an additional benefit if these materials were to be used for neutralisation in a bioleaching process for zinc recovery.
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- Klintman, Mikael, et al.
(författare)
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Academia and society in collaborative knowledge production towards urban sustainability : several schemes—three common crossroads
- 2022
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Ingår i: Environment, Development and Sustainability. - : Springer Science and Business Media LLC. - 1387-585X .- 1573-2975.
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Tidskriftsartikel (refereegranskat)abstract
- Arrangements for collaboration in knowledge production across academia, government, non-governmental organisations, and corporations have several names, such as citizen-science, community-based participatory research, engaged research and hybrid forums. The multiplicity of schemes does not lie only in the high number of names for various versions of collaborative knowledge production. Different scholars also use concepts in multiple ways, depending on their individual choices, mother disciplines, and the problem area in which collaboration occurs. At the same time, there is a lack of analytical tools that address the full range of collaborative research schemes and provide a systematic set of questions to learn about the schemes, challenges, and opportunities. Based on our review of academic journal articles highlighting collaborative research schemes, this paper aims to analyse three parameters which it is fair to say that virtually all arrangements of collaborative knowledge production ought to consider when making decisions, parameters that are often partially missed or misunderstood: (A) epistemic-procedural, (B) exclusive-inclusive and (C) aggregative-integrative. By examining the three parameters, their political theory origins, and how they connect to and challenge existing schemes of knowledge collaboration, we provide analytical tools that could facilitate processes of developing and scrutinising arrangements of collaborative research.
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- López, Cristian Daniel, 1990, et al.
(författare)
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Broadband Waveguide-to-Substrate Transition Using a Unilateral Etched Finline Structure
- 2019
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Ingår i: ISSTT 2019 - 30th International Symposium on Space Terahertz Technology, Proceedings Book. ; Proceedings Book 2019, s. 47-49
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Konferensbidrag (refereegranskat)abstract
- We present a novel broadband waveguide-tosubstrate transition that aims to be used for broadband mixer design. The transition consists of a unilateral finline structure with etched substrate between the fins. This particular feature reduces the overall insertion loss and facilitates matching with the waveguide. The transition is designed of a thin silicon substrate covered by a superconducting niobium thin layer. An auxiliary gold layer situated on top of the Nb-layer provides grounding for the fins and facilitates a simple mounting process in the split-block waveguide mount. In order to compare simulations with measurements, a back-to-back arrangement was designed and simulated using HFSS in the 211-373 GHz frequency band. The back-to-back simulation results show an insertion loss of less than 0.3 dB in the whole band. Furthermore, a fractional bandwidth of 55% with a return loss better than 15 dB is achieved
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