•Petroleum and coal raw material characteristics for needle coke production are reviewed.•Needle coke modifying additives are discussed and classified.•Needle coke modifying additive mechanism of ...action is discussed.
Needle coke, commonly used in the production of high-power graphite electrodes for steel production in electric furnaces, is a scarce product in the refining and by-product coke industry. In recent years, researchers have increasingly turned their attention to various ways of modifying the coal carbonizing process raw materials to produce needle coke and expanding the process raw material base. The review covers a study of different raw materials used to produce anisotropic carbon-based material and summarizes the raw material composition required for needle coke production. Furthermore, additives used to modify needle coke base oil or coal feedstock have been considered and classified according to their mechanism of action.
Al2O3-Ti2O3-Al sliding gates were prepared from Al2O3-Ti2O3 raw materials, sintered corundum and aluminum, and used in trials at steel works. The sliding gate with 30 wt% Al2O3-Ti2O3 added was used ...on an 80 t ladle for 4 cycles without macrocracks. The postmortem sliding gate can be divided into the permeation layer (0–0.1 mm), transition I layer (0.1–10 mm), transition II layer (10–20 mm) and unchanged layer from the hole working face outward. XRD, SEM and industrial CT were used to analyze the postmortem sliding gate. The results show that, in the Al2O3-Ti2O3-Al sliding gate, both Al and Ti2O3 are involved in reactions, Ti2O3 transforms into Ti2O and TiO in the transition I layer, and part of the Ti2O3 in the transition II layer transforms into Ti8O15. Titanium compounds with different densities are dispersed in the matrix and form microcracks to improve the thermal shock resistance of the sliding gate, which improved the performance.
Summary
The diversity of raw materials used in modern products, compounded by the risk of supply disruptions—due to uneven geological distribution of resources, along with socioeconomic factors like ...production concentration and political (in)stability of raw material producing countries—has drawn attention to the subject of raw material “criticality.” In this article, we review the state of the art regarding the integration of criticality assessment, herein termed “product‐level supply risk assessment,” as a complement to environmental life cycle assessment. We describe and compare three methods explicitly developed for this purpose—Geopolitical Supply Risk (GeoPolRisk), Economic Scarcity Potential (ESP), and the Integrated Method to Assess Resource Efficiency (ESSENZ)—based on a set of criteria including considerations of data sources, uncertainties, and other contentious methodological aspects. We test the methods on a case study of a European‐manufactured electric vehicle, and conclude with guidance for appropriate application and interpretation, along with opportunities for further methodological development. Although the GeoPolRisk, ESP, and ESSENZ methods have several limitations, they can be useful for preliminary assessments of the potential impacts of raw material supply risks on a product system (i.e., “outside‐in” impacts) alongside the impacts of a product system on the environment (i.e., “inside‐out” impacts). Care is needed to not overlook critical raw materials used in small amounts but nonetheless important to product functionality. Further methodological development could address regional and firm‐level supply risks, multiple supply‐chain stages, and material recycling, while improving coverage of supply risk characterization factors.
•Resource efficiency of PV recycling processes is analysed in different scenarios.•Processes with high-efficiency can recycle up to 83% of the waste panel.•Obtaining high-quality recycled materials ...from PV grants significant benefits.•The treatment of halogenated plastics represents a bottleneck for PV recycling.•Knowing the composition of panels is essential to boost their efficient recycling.
Although the amount of waste photovoltaic (PV) panels is expected to grow exponentially in the next decades, little research on the resource efficiency of their recycling has been conducted so far. The article analyses the performance of different processes for the recycling of crystalline silicon PV waste, in a life cycle perspective. The life cycle impacts of the recycling are compared, under different scenarios, to the environmental benefits of secondary raw materials recovered. Base-case recycling has a low efficiency and, in some cases, not even in line with legislative targets. Conversely, high-efficient recycling can meet these targets and allows to recover high quality materials (as silicon, glass and silver) that are generally lost in base-case recycling. The benefits due to the recovery of these materials counterbalance the larger impacts of the high-efficiency recycling process. Considering the full life cycle of the panel, the energy produced by the panel grants the most significant environmental benefits. However, benefits due to high-efficient recycling are relevant for some impact categories, especially for the resource depletion indicator. The article also points out that thermal treatments are generally necessary to grant the high efficiency in the recycling. Nevertheless, these treatments have to be carefully assessed since they can be responsible for the emissions of air pollutants (as hydrogen fluoride potentially released from the combustion of halogenated plastics in the panel’s backsheet). The article also identifies and assesses potential modifications to the high-efficiency recycling process, including the delocalisation of some treatments for the optimisation of waste transport and the introduction of pyrolysis in the thermal processing of the waste. Finally, recommendations for product designers, recyclers and policymakers are discussed, in order to improve the resource efficiency of future PV panels.
Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most ...interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.
The evolution of resource requirements in developed countries after the 2008 crisis seemed to indicate that there is a process of dematerialization. This paper analyses dematerialization in a group ...of developed countries and the effects of the economic cycle on resource use. The aim is to determine whether dematerialization can be linked to the effects of the economic crisis or, on the contrary, is independent of the economic context. To do this, a descriptive part is proposed in which the existence of dematerialization over the last 50 years is analysed. Subsequently, a model is estimated in which the effect of recessionary, low-growth and normal growth periods on the consumption of material resources is contrasted. The raw material input is used as an indicator of the use of material resources, which makes it possible to link each country to all the resources it requires for the normal functioning of its economy, regardless of where they are consumed. Among the main results, it can be noted that reductions in resource consumption occur in periods of recession and low growth, while for growth above 2% there is no dematerialization.
The proper use of alternative fuels and materials in the cement industry is essential for the planning and promotion of different methods that can decrease the environmental impacts, lower the ...consumption of energy and material resources, and reduce the economic costs of this industry. Because of the great potential for the cement industry to save energy and reduce greenhouse gas emissions (GHG), many new research advances associated with the promising approach of introducing waste materials as alternative fuels or sustainable raw materials into the cement manufacturing process have been developed in recent years. Therefore, the main objective of this paper is to provide a literature review of these approaches based on previously published research studies. The analysis is specially focused on the technical, economic, and environmental effects of the uses of five solid wastes, namely, municipal solid waste (MSW), meat and bone animal meal (MBM), sewage sludge (SS), biomass, and end-of-life tyres (ELT), in the cement industry.
The circular economy is an important concept in many areas of the world, many production sectors and above all within agricultural and food production. The agro-food sector has become especially ...aware of the problem of disposal and/or reuse of waste, which is better defined as "secondary raw materials" (SRM). The SRM of agro-food origin have an important value quantified in molecular and functional compounds.
We have reviewed many documents concerning food wastes and their re-evaluation as SRM in the agro-food industrial chain. In this work, we gathered scientific literature from the last 60 years regarding not only this concept but also the actual SRM composition of food and which among those can be obtained in compliance with the principle of a circular economy. Initially, our goal was to research and highlight SRMs derived from the processing and conservation of fruit.
The results showed the current state of both SRM production and their possible and current use. The data revealed that the main sectors in witch SRM are actually employed are chemical, pharmaceutical, food and nutraceutical ones. We also found that the amount of discarded parts overall represents 50% for all fruit families. In a systematic way, the gaps that the current system shows in the aspects of the valorisation of the SRM have been highlighted. The wide diversity of uses for SRMs obtained from food have emerged a common factor and a guiding thread for the evaluation of these by products. Their reutilization has been highlighted considering different families of fruit plants and the SRMs produced within.
Display omitted
•The studies on secondary raw materials (SRM) hugely increased in the last 60 years.•The SRM are used in the chemical, pharmaceutical, food and nutraceutical sectors.•The total quantity of parts discarded represents 50% for all fruit families.•About 60% of Eriaceae (berry fruits) are actually discarded.•Peel is the most frequently discarded part.
This contribution presents the state of the art of economy-wide material flow accounting. Starting from a brief recollection of the intellectual and policy history of this approach, we outline system ...definition, key methodological assumptions, and derived indicators. The next section makes an effort to establish data reliability and uncertainty for a number of existing multinational (European and global) material flow accounting (MFA) data compilations and discusses sources of inconsistencies and variations for some indicators and trends. The results show that the methodology has reached a certain maturity: Coefficients of variation between databases lie in the range of 10% to 20%, and correlations between databases across countries amount to an average R2 of 0.95. After discussing some of the research frontiers for further methodological development, we conclude that the material flow accounting framework and the data generated have reached a maturity that warrants material flow indicators to complement traditional economic and demographic information in providing a sound basis for discussing national and international policies for sustainable resource use.
material footprint of nations Wiedmann, Thomas O.; Schandl, Heinz; Lenzen, Manfred ...
Proceedings of the National Academy of Sciences - PNAS,
05/2015, Letnik:
112, Številka:
20
Journal Article
Recenzirano
Odprti dostop
Significance This original research paper addresses a key issue in sustainability science: How many and which natural resources are needed to sustain modern economies? Simple as it may seem, this ...question is far from trivial to answer and has indeed not been addressed satisfactorily in the scholarly literature. We use the most comprehensive and most highly resolved economic input–output framework of the world economy together with a detailed database of global material flows to calculate the full material requirements of all countries covering a period of two decades. Called the “material footprint,” this indicator provides a consumption perspective of resource use and new insights into the actual resource productivity of nations.
Metrics on resource productivity currently used by governments suggest that some developed countries have increased the use of natural resources at a slower rate than economic growth (relative decoupling) or have even managed to use fewer resources over time (absolute decoupling). Using the material footprint (MF), a consumption-based indicator of resource use, we find the contrary: Achievements in decoupling in advanced economies are smaller than reported or even nonexistent. We present a time series analysis of the MF of 186 countries and identify material flows associated with global production and consumption networks in unprecedented specificity. By calculating raw material equivalents of international trade, we demonstrate that countries’ use of nondomestic resources is, on average, about threefold larger than the physical quantity of traded goods. As wealth grows, countries tend to reduce their domestic portion of materials extraction through international trade, whereas the overall mass of material consumption generally increases. With every 10% increase in gross domestic product, the average national MF increases by 6%. Our findings call into question the sole use of current resource productivity indicators in policy making and suggest the necessity of an additional focus on consumption-based accounting for natural resource use.
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