Recovery of critical and other raw materials from mining waste and landfills

The transition to a more circular economy is essential to develop a sustainable, low carbon, resource efficient, and competitive economy in the EU. In this context Critical Raw Materials (CRM) are defined as those which are of particularly great importance to the EU economy and at the same time there is a high risk of supply disruptions. First and foremost, improving the circular use of CRM is a key strategy in improving the security of supply and not surprisingly is an objective of various policy documents. This report delivers on action #39 of the Circular Economy Action Plan: "Sharing of best practice for the recovery of critical raw materials from mining waste and landfills". It builds on discussions held during two 2018 workshops and gathers together six examples of existing practices for the recovery of critical, precious, and other materials from extractive waste and landfills, highlighting technological innovation and contributions that have been made to a more comprehensive knowledge-base on raw materials. The report also provides various estimates of potential recovery of certain materials compared to their current demand. Lessons learnt from the practices include awareness that it is very unlikely that recovery processes can target one or just a few specific materials of great interest and disregard other elements or bulk matrixes. Especially in case of very low concentrations, most of the mineral resources and other bulk materials in which they are embedded must be valorised in order to increase economic viability and minimise waste disposal. As recovery processes can be very energy intensive, environmental and land use related aspects are also particularly relevant even though environmental gains may also occur and, moreover, land space can be liberated and reused for new purposes and services. Finally, availability of data and information on secondary materials as well as a harmonized legislative framework within the EU appear to be crucial for the large-scale deployment of recovery practices.JRC.D.3-Land Resource

Recovery and refining of precious metals alloys by oxi-nitrogen leaching

In recent years the demand for gold and other precious metals has increased dramatically, insomuch as in the last decade gold prices have quintupled. In the contest of the lack of trust in the traditional financial market, recovery and refining of precious metals from e-waste, automotive catalysts, and scrap jewellery and waste generated by jewellery manufacture have become increasingly more important. Controlled recovery of precious metals reduces additional waste production and helps prevent the need for supplementary mining. Metal recovery and refining processes can also have adverse effects on the environment when not conducted properly, especially when the pressure of the precious metals market price makes the refining companies speed up production. Separation technology described here is the hydrometallurgical method whereby gold-bearing alloys are obtained from gold scraps and wastes. Different metal grades are refined by aqua-regia or nitric acid dissolution in the presence of oxi-nitrogen species

Challenges and Prospects of Steelmaking Towards the Year 2050

The world steel industry is strongly based on coal/coke in ironmaking, resulting in huge carbon dioxide emissions corresponding to approximately 7% of the total anthropogenic CO2 emissions. As the world is experiencing a period of imminent threat owing to climate change, the steel industry is also facing a tremendous challenge in next decades. This themed issue makes a survey on the current situation of steel production, energy consumption, and CO2 emissions, as well as cross-sections of the potential methods to decrease CO2 emissions in current processes via improved energy and materials efficiency, increasing recycling, utilizing alternative energy sources, and adopting CO2 capture and storage. The current state, problems and plans in the two biggest steel producing countries, China and India are introduced. Generally contemplating, incremental improvements in current processes play a key role in rapid mitigation of specific emissions, but finally they are insufficient when striving for carbon neutral production in the long run. Then hydrogen and electrification are the apparent solutions also to iron and steel production. The book gives a holistic overview of the current situation and challenges, and an inclusive compilation of the potential technologies and solutions for the global CO2 emissions problem

Materials and design principals for a Circular, Biobased construction industry

The construction industry has traditionally operatedwith linear economy principals, with buildings being demolishedrather than recycled following the end of thedesign life. The industry can play a major role in reducingrequirements for valuable natural resources and promotingsustainable design and construction by adopting practicesadhering to circular economy principals. Central to thiswould be the use of renewable bio-based construction materialsand designing buildings for disassembly - with abuildings’ elements and connecting components designedto be reused, rearranged in a different configuration orrecycled following the expiration of the buildings’ initialfunctional use

Phase equilibria studies and beneficiation of titaniferous slags

Titaniferous magnetite (titanomagnetite) offers a unique opportunity for the production of three valuable products from one resource. It generally contains economically appreciable reserves of vanadium and iron as well as significant contents of titanium. Titanomagnetite is typically smelted in blast or electric furnaces in the presence of reductant and fluxes (dolomite and quartz) to produce a valuable vanadium bearing pig iron and a virtually valueless titaniferous slag. The titaniferous slag by-products are generally defined by the Ca-Mg-Al-Si-Ti-O system. These fluxed slags can contain as high as 20-40wt% TiO2 (titania). The lack of interest in processing titaniferous slags to produce saleable titania materials is attributed to the presence of chemically inert phases, like the spinel solid solution [Mg(Al,Ti,V)2O4] that cannot be handled by the available titania slag upgrading technologies. The understanding of phase relations in titaniferous slags is thus important in order to be able to implement a suitable fluxing strategy for the production of a treatable titaniferous slag with no inert spinel phase. The available phase equilibria data established in air for titaniferous slags is inconclusive about the possible crystallisation of the detrimental spinel. However, literature on phase compositions of plant titaniferous slags are conclusive about the crystallisation of Mg(Al,Ti,V)2O4 in high MgO and Al2O3 bearing slags. It is thus clear that the understanding of phase relations in titaniferous slags requires further development. The objective of the current project was to investigate the phase equilibria and beneficiation of titaniferous slags to produce a saleable titania product. As a development to previous work, the composition of the slag for review was based on the available work, namely; TiO2 = 37.19wt%, SiO2 = 19.69wt%, and Al2O3 = 13.12wt%, at varying proportions of CaO (30- 0wt%) and MgO (0-30wt%). The phase equilibria studies followed a systematic approach involving the review and validation of the available equilibrium phase diagram produced in air, followed by the determination of updated phase equilibria at low oxygen partial pressures (pO2) of 10-16 atm applicable to titanomagnetite smelting. The generic approach of studying phase equilibria in multicomponent systems was followed, namely; (1) literature survey of the available thermodynamic and phase equilibria data applicable to the reviewed system, (2) calculation and re-drawing of the equilibrium phase diagrams using FactSage thermochemical software, and (3) equilibration-quench-(electron probe micro analysis) (EPMA) experiments to the validate calculated equilibrium phase relations. A titaniferous slag with little crystallisation of the inert spinel phase, based from the best fluxing strategy with an MgO-free limestone, was produced by smelting in conventional (using alumina crucible) and cold copper crucible induction furnaces for subsequent beneficiation using the established Upgraded Slag (UGS) process. A conceptual flowsheet for the production of vanadium, steel and titanium products was therefore designed and subsequently subjected to economic evaluation using the discounted cash flow (DCF) modelling approach. Thermodynamic and phase equilibria literature for the Ca-Mg-Al-Si-Ti-O system demonstrated that this system and some subsystems are well researched in air, and not as much in low pO2 atmospheres applicable to smelting operations. The FactSage software used in the current study for the calculation of phase equilibria in the Ca-Mg-Al-Si-Ti-O system applicable to titaniferous slags does not have tialite (Al2TiO5) modelled as a component in the customary pseudobrookite solution database - Al2TiO5 is a component of the pseudobrookite solution reported in literature for the current system. Hence, a private pseudobrookite solution database applicable to the reviewed system, i.e. MgTi2O5-Al2TiO5-Ti3O5, was developed and incorporated into FactSage before any calculation could be conducted. Thermodynamic modelling of the MgTi2O5-Al2TiO5-Ti3O5 system was conducted through the CALculation of PHase Diagram (CALPHAD) method. The sublattice model coupled with compound energy formalism (CEF) and Redlich-Kister polynomial were adopted. The model information was incorporated into FactSage to create a private database for subsequent calculations of phase equilibria of titaniferous slags. The equilibrium phase diagram for the Ca-Mg-Al-Si-Ti-O system in the same compositional range as in the available literature was then calculated in air. The liquidus surfaces and phase relations in the equilibrium phase diagrams of available literature and FactSage calculation are fairly comparable. However, at high MgO concentrations: FactSage calculation predicts that Mg(Al,Ti)2O4 is the primary phase, followed by successive crystallisation of pseudobrookite solid solution (MgTi2O5-Al2TiO5) and forsterite (Mg2SiO4); and the available literature reports MgTi2O5-Al2TiO5 as the primary phase, followed by Mg2SiO4. The crystallisation of spinel phase in the available phase diagram produced in air is not predicted. The crystallisation of the spinel solid solution phase in titaniferous slags is extensively reported in the open literature. Equilibration-quench-EPMA experimental results produced in air generally compared well to the FactSage calculations. The inability of the available phase diagram to predict spinel phase crystallisation was attributed to the lack of sensitive analytical techniques in the late 1960s, when the available phase diagram was developed. The phase equilibria of titaniferous slags were further calculated at low pO2 atmospheres of 10-16 atm. In the reviewed compositional range of titaniferous slags, the liquidus surface and Ti3+/Ti4+ mass fraction ratio increased with decreasing the pO2. There was no significant difference in terms of the crystallisation of phases between the calculated results in air and at pO2 of 10-16 atm, except that the size of the primary phase field at higher MgO concentrations than the composition for the minimum liquidus temperature increased and the pseudobrookite solution included Ti3+ bearing phase, i.e. MgTi2O5-Al2TiO5-Ti3O5. Equilibration-quench-EPMA experimental results produced at pO2 of 10-16 atm generally compared well to the FactSage calculations. The new phase equilibria at low pO2 of 10-16 atm shows that the crystallisation of the chemically inert Mg(Al,Ti)2O4 in titaniferous slags would occur if the slag contains high Al2O3 concentration and MgO concentration of 2wt% and above. However, the crystallisation of Mg(Al,Ti)2O4 in titaniferous slag is not significantly sensitive to variation in the TiO2 concentration in, and basicity of the slag. To produce a titaniferous slag with minimum possible inert spinel content for subsequent beneficiation, the South African Main Magnetite Layer (MML) titanomagnetite concentrate was smelted in the presence of an MgO-free lime and low ash Sasol carbon (SASCARB) reductant. This smelting approach would produce a titaniferous slag with about 4wt% MgO, which would come from the titanomagnetite - based on the phase equilibria, this slag should crystallise a small amount of the inert spinel. When the smelting was conducted in an alumina crucible placed inside a conventional induction furnace, the slag was inevitably contaminated by Al2O3 from the refractory container. This slag crystallised a significant Mg(Al,Ti)2O4 with the content approximated by the MgO concentration - the significant Mg(Al,Ti)2O4 crystallisation was attributed to the Al2O3 saturation in the titaniferous slag. A titaniferous slag containing a treatable ulvospinel phase was produced in a cold copper crucible induction furnace - the crystallisation of the ulvospinel, instead of the chemically inert spinel solid solution was attributed to the saturation of the slag by iron from the incomplete reduction process due to the inevitable stoppage of the heat supply to the induction furnace as soon as the susceptor iron metal and produced pig iron settled at the bottom of the copper crucible. For the purpose of demonstrating the feasibility of producing titania products from titaniferous slags, this slag was also subjected to beneficiation using UGS process. The current study successfully demonstrated that the titaniferous slags can be beneficiated to saleable titania products using the UGS process: the TiO2 in the Mg(Al,Ti)2O4 bearing waste titaniferous slag produced by the defunct Evraz Highveld Steel and Vanadium Corporation (EHSV) was upgraded from about 33wt% to 75wt%, while the TiO2 in the titaniferous slags produced in conventional and cold crucible induction furnaces were upgrade from about 30wt% to 67wt% and 22.00wt% to 90.45wt%, respectively. The remaining impurities in the 75wt% and 67wt% TiO2 UGS products were mainly MgO and Al2O3 contained in the refractory spinel solid solution. In the case of the 67wt% TiO2 product, there was excess Al2O3 in the spinel structure - the excess Al2O3 remained in the glass phase. Though the 90.45wt% TiO2 product is attractive for use as feedstock for the production of the preferred chloride pigment, this product however contained finer PSD and higher concentrations of impurities such as SiO2, Al2O3, and CaO, than the specification for the chloride process feedstock. This product was thus not a suitable feedstock for the chloride pigment production. Further optimisation of the UGS conditions has a potential to reduce the concentrations of impurities to levels suitable for feedstock for the preferred chloride pigment production process. Further investigations are also required to study the feasibility of the chlorination of micro-pellets of the UGS product. Since the UGS product is mainly composed of rutile structure, it would not be a suitable feed for the sulfate pigment production as the sulfuric acid lixiviant is unable to dissolve the rutile structure. Only if soluble in sulfuric acid, this high TiO2 bearing UGS product produced from titaniferous slags could be used as advantageous feedstock for the sulfate pigment production in terms of the minimization of the reagent consumption and the amount of the toxic sulfate waste. Based on the work of the current study, literature data and Pyrosim simulations, a conceptual process flowsheet for the production of vanadium slag, steelmaking pig iron and titania product was proposed. The economic modelling of the conceptual flowsheet for a 20 year operational projection showed that the process is economically viable. The process economic viability is sensitive to variation in the Opex and Revenue. In addition, additives, such as the amount and type of reductant, fluxes, and reagents account for about 75% of the Opex. It is possible that the additives are overestimated in the process as the recycle streams were not included in the proposed process and economic model. At the same time, the economic model does not consider the environmental and waste management costs. Hence, the economic analysis is considered to be preliminary in nature, or indicative at best. The current study has demonstrated that (1) a titaniferous slag containing little or no inert spinel phase that is suitable for upgrading can be produced when the MgO content in the slag is below 2wt% - the best approach to producing a slag with minimum possible MgO content would be to smelt the titanomagnetite in the presence of an MgO-free limestone flux and low ash reductant, and (2) it is technically and economically feasible to produce three products, i.e. V slag, steelmaking pig iron, and titania product, from titanomagnetite

Energy saving technologies and optimisation of energy use for decarbonised iron and steel industry

The iron and steel industry relies significantly on fossil energy use and is one of the largest energy consumers and carbon emitters in the manufacturing sector. Simultaneously, a huge amount of waste heat is directly discharged into the environment during steel production processes. Conservation of energy and energy-efficient improvement should be a holistic target for iron and steel industry. There is a need to investigate and analyse potential effects of application i.e., a number of primary and secondary energy saving and decarbonisation technologies to the basic energy performance and CO2 emissions profile of iron and steel industry. A 4.7Mt annual steel capacity iron and steel plant in the UK is selected as a case study. By carrying out a comprehensive literature review of current primary and secondary energy saving and decarbonisation technologies, suitable technologies are categorised based on their purpose of utilisation and installation positions. It is found that fuel substitution technologies and waste heat recovery technologies have wide application prospects in iron and steel industry. To further investigate effects of these technologies on the UK integrated steelwork, a comprehensive model of iron and steel production processes is built by using the software Aspen Plus. The model is fully validated and is used to examine the specific energy consumption and direct CO2 emissions. Energy consumption and CO2 emissions of whole production chain to produce a ton of crude steel are 17.5 GJ and 1.06 t. Waste heat from hot coke and gas cooling could cover 40% of electricity consumed in the plant if coking process has the maximum coke capacity. To implement primary energy saving and decarbonisation technologies, the performance of blast furnace is optimised first by substituting coke with bio-reducers based on the proposed model. Three biomass substitutions are considered to reduce coke rate and CO2 emissions of ironmaking process. Results show that coke demand of per ton of hot metal and CO2 emissions of the ironmaking process are improved by replacing partial coke with biomass. An optimal coke replacement is operated with 200 kg bio-oil and 222 kg coke when producing one ton of product. The reaction involving bio-syngas has the most potential to reduce CO2 emissions. To find a sustainable way to capture CO2 and recover waste heat onsite, a model of adopting organic Rankine cycle with amine-based CO2 capture in ironmaking process is introduced. In comparison with different reducing agents injected into BF, bio-oil has the most advantage to improve energy consumption of CO2 capture system. CO2 emissions from total sites can be maximumly reduced by 69% through the method of CO2 capture with waste heat recovery technologies. The combination of various decarbonised technologies creates great opportunity to reduce CO2 emissions. A mass-thermal network of iron and steel industry is finally built up, where primary and secondary energy saving technologies are implemented to optimise energy use and reduce CO2 emissions. The general guideline i.e., 5-step method is summarised to optimise the mass-thermal network. Exergy analysis is used to evaluate overall network after applications of energy saving and decarbonisation technologies. Injection of biomass-based syngas can maximumly increase the exergy efficiency of ironmaking process. Sinter and BOF steelmaking processes are related with mass ratio of hot metal. Optimisation insights of energy use and decarbonisation for steelwork are revealed based on exergy efficiency and destruction results

Decarbonization of construction supply chains - Achieving net-zero carbon emissions in the supply chains linked to the construction of buildings and transport infrastructure

Sweden has committed to reducing greenhouse gas (GHG) emissions to a net-zero level by Year 2045. In Sweden, about 20% of its annual CO2 emissions are from the manufacture, transport and processing of materials for both the construction and refurbishment of buildings and transport infrastructure. Cement and steel, together with diesel use in construction processes and material transport account for the majority of the CO2 emissions associated with building and infrastructure construction.This thesis assesses the challenges associated with reducing CO2 emissions from the supply chains for buildings and transport infrastructure construction. The main aim is to determine the extent to which abatement technologies across the supply chain can reduce the GHG emissions associated with construction if combined to exploit their full potential, while identifying key barriers towards their implementation.The work takes its starting point from material, energy and emissions flow analyses conducted across the construction supply chain, followed by the development of stylized models, which are subsequently used for scenario analysis. This quantitative analysis work is integrated with a participatory process that involves relevant stakeholders in the assessment process. The participatory process serves to identify the main abatement options, as well as to adjust decisions and assumptions regarding abatement portfolios and timelines, so as to make these as realistic and feasible as possible. Supported by a comprehensive literature review, a detailed inventory of abatement options in the supply chain of building and transport infrastructure construction is developed. This includes technologies and practices that are currently available and that are deemed available on a timescale up to Year 2045.The results show that on a national level, it is possible to reduce GHG emissions associated with the construction of buildings and transport infrastructure by 50% up to Year 2030, through applying already available measures. Moreover, it will be feasible to reach close-to-zero emissions by Year 2045, with this requiring comprehensive measures across-the-board, including breakthrough technologies for heavy vehicles, cement and steel production. Attaining the full abatement potential of measures that are already available would rely on sufficient availability of sustainably produced second-generation biofuels, requiring accelerated implementation of alternative abatement measures, involving optimization of material use, mass handling and transport systems, as well as the use of alternative materials and designs, with focus on circularity and material efficiency measures. To realize the potential linked to applying measures across the supply chain, there is a need for extensive collaboration along the whole value chain. Policy measures and procurement strategies should be aligned to support these measures with a clear supply chain focus, so as to enable balanced risk sharing and the involvement of contractors early in the planning and design process.The results also illustrate the importance of intensifying efforts to identify and manage both soft and hard barriers to implementation and the importance of acting promptly to implement available measures (e.g., material efficiency, recycling and material/fuel substitution measures) while actively planning for long-term measures (electrification of heavy vehicles and low-CO2 steel or cement). There are immediate and clear needs to prepare for deeper abatement and associated transformative shifts and to consider carefully the pathway towards these goals while avoiding pitfalls along the way, such as an over-reliance on biofuels or cost optimizations that cannot be scaled up to the levels required to reach deep emissions reductions.Therefore, strategic planning must be initiated as early as possible, as lead times related to planning, securing permits and construction of the support infrastructure (renewable electricity supply, electricity grid expansion, hydrogen storage, CCS infrastructure) and piloting and upscaling to commercial scale of the actual production units will all influence the speed of change

Best Available Techniques (BAT) Reference Document:for:Iron and Steel Production:Industrial Emissions Directive 2010/75/EU:(Integrated Pollution Prevention and Control)

The BREF entitled ‘Iron and Steel Production’ forms part of a series presenting the results of an exchange of information between EU Member States, the industries concerned, non-governmental organisations promoting environmental protection and the Commission, to draw up, review, and where necessary, update BAT reference documents as required by Article 13(1) of the Directive. This document is published by the European Commission pursuant to Article 13(6) of the Directive. This BREF for the iron and steel production industry covers the following specified in Annex I to Directive 2010/75/EU, namely: • activity 1.3: coke production • activity 2.1: metal ore (including sulphide ore) roasting and sintering • activity 2.2: production of pig iron or steel (primary or secondary fusion) including continuous casting, with a capacity exceeding 2.5 tonnes per hour. The document also covers some activities that may be directly associated to these activities on the same site. Important issues for the implementation of Directive 2010/75/EU in the production of iron and steel are the reduction of emissions to air; efficient energy and raw material usage; minimisation, recovery and the recycling of process residues; as well as effective environmental and energy management systems. The BREF document contains 13 chapters. Chapter 1 provides general information on the iron and steel sector. Chapter 2 provides information and data on general industrial processes used within this sector. Chapters 3 to 8 provide information on particular iron and steel processes (sinter plants, pelletisation, coke ovens, blast furnaces, basic oxygen steelmaking and casting, electric arc steelmaking and casting). In Chapter 9 the BAT conclusions, as defined in Article 3(12) of the Directive, are presented for the sectors described in Chapters 2 to 8.JRC.J.5-Sustainable Production and Consumptio

Gas, Water and Solid Waste Treatment Technology

This book introduces a variety of treatment technologies, such as physical, chemical, and biological methods for the treatment of gas emissions, wastewater, and solid waste. It provides a useful source of information for engineers and specialists, as well as for undergraduate and postgraduate students, in the areas of environmental science and engineering