Predicted effect of ore composition on slag formation in manganese ore reduction

Previous work showed that manganese ore reduction rates are strongly influenced by the extent of slag phase formation. In this work, the effect of ore composition on slag formation during manganese oxide reduction was predicted using thermochemical calculations; FactSage 6?4 was used to calculate the equilibrium phase relations in the oxide system MnO–SiO2–CaO–MgO– Al2O3. Practically observed differences in ore composition, even within the same orebody, are predicted to cause significant differences in slag formation during reduction, with large differences in ore reducibility expected.http://www.maneyonline.com/loi/mpm2015-09-30hb201

Die roman 'Magersfontein, O Magersfontein' van Etienne Leroux as satire van die Suid-Afrikaanse werklikheid

Mini-scripsie.Proefskrif (M.A.) -- Universiteit van Stellenbosch, 1979.Full text to be digitised and attached to bibliographic record

Framework for developing coworking spaces through sustainable refurbishment in South Africa

Thesis (MEng)--Stellenbosch University, 2019.ENGLISH ABSTRACT: The study was conducted as the changing nature of work, global trends and South African market conditions indicated the need for coworking spaces. The aim of the study is to assist the development manager of coworking spaces projects in the development process. A grounded theory methodology was used to develop a conceptual framework. As guideline, the Professional Consultants Services Agreement Committee (PROCSA) matrix was used to build the conceptual framework. The PROCSA matrix states the general roles and responsibilities of all parties involved in a construction project for the lifecycle of the project, including the development manager. Requirements were added to the general roles and responsibilities of the development manager, these requirements can be divided into four main categories. Coworking requirements comprised of a coworking member typology matrix, general coworking characteristics and specific location selection requirements. Refurbishment requirements included the need for deep energy refurbishment, vacant sites, flexible refurbishment design and thorough assessment of refurbishment characteristics. Sustainable requirements included a minimum four star green rating according to the green building council of South Africa and several additional requirements to use the office rating tool. Construction management requirements included the use of an eight step method aimed at reducing waste in refurbishment projects through implementing lean construction principles. The study was validated by conducting a theoretical case study on a coworking space completed in the second half of 2018. After the theoretical case study, subject matter experts in the industry were interviewed with the results from the case study and the conceptual framework to gather further input on the conceptual framework.AFRIKAANSE OPSOMMING: Die studie is uitgevoer omdat globale tendense in SuidAfrikaanse kondisies die behoefte vir saamwerkspasies toon. Die doel van die studie is om die ontwikkelingsbestuurder van saamwerkspasies te ondersteun in die ontwikkelingsproses. ’n Gegrondeteorie metodologie is gebruik om ’n konsepsuele raamwerk te ontwikkel. Die konsepsuele raamwerk het gebruik gemaak van die Komitee vir Professionele Konsultante Ooreenkomstematriks (KPKO) as riglyn. Die KPKOmatriks benoem die rolle en verantwoordelikhede van alle partye wat betrokke is in ’n konstruksie projek vir die lewensiklus van die projek, insluitend die ontwikkelingsbestuurder. Vereistes is by die algemene rolle en verantwoordelikhede van die ontwikkelingsbestuurder gevoeg. Hierdie vereistes kan in vier hoofkategorie verdeel word. Saamwerkspasie vereistes sluit in die gebruik van ’n tipologiematriks van ’n saamwerkspasie se lede, algemene karakteristieke van ’n saamwerk spasie sowel as spesefieke vereistes vir die keuse van liggings. Opknappingsvereistes sluit in die toepassing van die energie opknapping, vakante geboue of dele van geboue, buigbare opknappingsontwerp sowel as ’n deeglike evaluering van die opknappingseienskappe. Volhoubare vereistes sluit ’n minimum vierstergroengradering volgens die groenbouraad van Suid Afrika in sowel as verskeie bykomende vereistes om die kantoorwaarderingsinstrument te gebruik. Vereistes vir konstruksiebestuur sluit die gebruik van ’n agtstapmetode in wat gemik is op die vermindering van afval in opknappingsprojekte deur die toepassing van skraal konstruksiebeginsels. Die studie is bekragtig deur ’n teoretiese gevallestudie te doen oor ’n saamwerkspasie wat in die tweede helfte van 2018 voltooi is. Na die teoretiese gevallestudie, is vakkundiges in die industrie met die resultate van die gevallestudie en die konseptuele raamwerk genader om verdere insette oor die konsepsuele raamwerk te versamel.Master

Fundamental and formation aspects of slag freeze linings : a review

Traditionally, pyrometallurgical reactors are lined on the inside with refractory materials. Some of the high-temperature phases are aggressive towards the furnace lining, requiring periodic repair or replacement of the lining. The freeze-lining concept, however, involves the deliberate formation of a layer of solidified bath material on the inner walls of the reactor lining. This self-repairing freeze lining can protect the reactor lining from corrosive attack by the liquid phases. Hence, this can be a solution for the periodically required lining replacement. However, the existing somewhat limited knowledge is mostly based on primary metal production systems, and future applications (with secondary feed materials for recycling purposes) will require more fundamental knowledge on the influencing parameters. This review collects the current knowledge regarding freeze linings. The various methods used to experimentally investigate freeze-lining phenomena experimentally are discussed. Then the generally accepted mechanism controlling freeze-lining formation is presented, followed by a listing of various influencing parameters. Next, the various mathematical models and approaches used to describe freeze-lining thickness are introduced. The remaining challenges conclude this review

Phase equilibria and thermodynamic evaluation of the Fe-Ti-V-O system in air

In this study, the iron-titanium-vanadium-oxygen (Fe-Ti-V-O) system in equilibrium with air was studied experimentally by high-temperature equilibration, quenching, scanning electron microscope and microprobe analysis coupled with critical assessment and thermodynamic evaluation. The properties of the liquid phase were successfully described with the quasichemical model by optimizing parameters only related to the Fe-Ti-O system; remaining parameters for the Fe-V-O and Ti-V-O sub-systems were adopted from recent optimisations. The model for the rutile and hematite solid solutions were described with the compound energy formalism. The ferropseudobrookite solid solution was modelled with a simple polynomial model to include a small solubility V 2 O 5 . A final set of self-consistent thermodynamic parameters was estimated within acceptable error limits. Calculated isothermal projections at 1000 °C, 1100 °C, 1200 °C, 1300 °C, and 1400 °C of the Fe-Ti-V-O system in equilibrium with air are presented and compared to experimental observations.Peer reviewe

Phase equilibria and thermodynamic evaluation of the Fe-V-O system in air

The Fe-V-O system in air was studied experimentally ranging from 700 °C to 1450 °C by high-temperature equilibration, quenching, scanning electron microscope and microprobe analysis. The thermodynamic evaluation was performed with FactSage 7.0. The solubility of V2O5(s) in Fe2O3(s) was described with the compound energy formalism. The properties of the liquid phase were described with both the quasichemical model and the associate species model. A set of self-consistent thermodynamic parameters were estimated within acceptable error limits. The calculated phase diagram of Fe-V-O in air is presented and compared to experimental observations and other literature data.Peer reviewe

Phase equilibria and thermodynamic evaluation of the Ti-V-O system in air

The Ti-V-O system was studied experimentally from 700 °C to 1500 °C by high-temperature equilibration, quenching, scanning electron microscope and Energy-Dispersive X-Ray spectroscopy. The solubility of titanium in the slag is less than 3 mol% at 1500 °C and the vanadium solubility in the rutile phase reached a maximum of 7.8 mol% at 1400 °C. The thermodynamic evaluation was performed with FactSage 7.0. The solubility of vanadium in the rutile phase was developed within the framework of the compound energy formalism. The properties of the liquid phase were described with the quasichemical model. A set of self-consistent thermodynamic parameters was estimated well within acceptable limits. The calculated phase diagram of the Ti-V-O system in air is presented and compared to experimental observations and other phase diagram data from literature.Peer reviewe

Investigation of waste PCB leach residue as a reducing agent in smelting processes

The advancement in technology has resulted in the development of newer and improved electrical products. The older products are becoming obsolete and are discarded as waste at a continuously increasing trend. Printed circuit board (PCB) is the main focus of electronic waste recycling because of the inherently high value of contained metals such as gold and copper. Hydrometallurgical route, which is often used to recover the metals, does not take into account the non-metallic PCB fractions. These non-metallic fractions may end up in landfills or incinerated which leads to secondary pollution. In this work, the use of the leached PCB waste fraction as reductant in primary metal smelting operations and solid state reduction is investigated. Laboratory-scale experiments and thermodynamic modelling were performed to simulate solid state reduction of hematite (Fe2O3) using various blends of PCB and graphitic carbon. Differential Scanning Calorimeter (DSC) analysis of several samples were performed up to 1200 °C. Thermodynamic modelling was done using FactSage to predict the products of the hematite reduction below 1600 °C. The study showed that PCB residue might be used to partially replace the conventional reductants. The investigations revealed that at temperatures below 1000 °C, PCB reduces hematite to lower forms of iron oxide at a faster rate than that of graphite. The optimal blend contains about 20 wt% PCB residue which has the same reduction degree as graphite. Thermodynamic modelling of iron smelting was also performed using various blends of PCB and coal. The models showed that PCB residue might be used to partially replace the conventional reductants. The study revealed that in iron smelting, the optimal blend contains around 20 wt% PCB residue, with energy savings of 150 kWh/t of ore to achieve the same metal recovery.Peer reviewe