Search results for " recycling"
showing 10 items of 131 documents
Generation of early Archaean grey gneisses through melting of older crust in the eastern Kaapvaal craton, southern Africa
2014
Abstract We report zircon ages, Hf-in-zircon isotopes as well as whole-rock geochemistry and Hf–Nd isotopic systematics for Palaeoarchaean grey gneisses of the Ancient Gneiss Complex of Swaziland, the oldest components of the Kaapvaal craton, southern Africa. The Hf-in-zircon isotopic compositions in these compositionally heterogeneous, multicomponent, migmatitic gneisses are highly variable, even in the oldest zircons dating back to 3.66 Ga, suggesting growth of zircon from melts representing a mix of juvenile and anatectic material derived from differentiated continental crust of Eoarchean to late Hadean age. In contrast, the initial Nd and Hf whole-rock isotopic compositions are frequent…
Palaeozoic arc magmatism in the Central Asian Orogenic Belt of Kazakhstan: SHRIMP zircon ages and whole-rock Nd isotopic systematics
2008
Abstract Early Palaeozoic tonalite to granodiorite intrusions in northern Kazakhstan are associated with lode gold mineralization and have SHRIMP zircon ages of 457.3 ± 6.6 Ma (Aksu), 452.9 ± 5.6 Ma and 447.4 ± 5.4 Ma (both Zholymbet). The Stepnyak intrusion contains large xenoliths with an age of 480.6 ± 5.0 Ma. One early Palaeozoic zircon from a porphyritic diorite at Stepnyak has a core with a near-concordant 207Pb/206Pb age of 3888 ± 1.5 Ma, whereas other xenocrystic grains are between 983 and 2698 Ma old. The early Archaean age is probably inherited from unexposed basement of the Kokchetav Massif and represents the oldest crustal material so far known from the Asian continent. It appea…
Numerical modelling of PT-paths related to rapid exhumation of high-pressure rocks from the crustal root in the Variscan Erzgebirge Dome (Saxony/Germ…
2002
Abstract The Bohemian Massif in the Central European Variscides contains many crustal slices with (ultra-)high-pressure rocks related to continent-continent collision. After closure of pre-existing oceans during the Devonian, excess crustal thickness was maintained for about 50 Ma until at around 340 Ma large volumes of high-pressure rocks from the crustal root were exhumed within a few million years. We relate this event to delamination and complete detachment of the lithospheric mantle, causing a crustal-scale isostatic instability. In the Erzgebirge dome, a model region in the northern part of the massif, an array of interrelated PTtd-paths with “decompression/cooling” and “decompression…
Andean Cenozoic volcanic centers reflect basement isotopic domains
1992
Isotopic data for Quaternary volcanic centers from lat 17.5° to 22°S in northern Chile provide evidence for crustal contributions to arc magma genesis in the central Andes and delineate basement domains. Crustal thickness, distance from trench, height of volcanic edifices above the seismically active subduction zone, and sediment supply to the trench are all constant along this segment of the arc. The only significant variable is crustal age (Paleozoic in the south, Proterozoic in the north). Pb isotopic compositions of Quaternary lavas in the northern sector are lower ( 206 Pb/ 204 Pb = 17.89-18.28) and Sr and O isotope ratios are less variable ( 87 Sr/ 86 Sr = 0.7058-0.7077, δ 18 O = +6.5…
Recycling and transport of continental material through the mantle wedge above subduction zones: A Caribbean example
2016
Abstract Estimates of global growth rates of continental crust critically depend upon knowledge of the rate at which crustal material is delivered back into the mantle at subduction zones and is then returned to the crust as a component of mantle-derived magma. Quantification of crustal recycling by subduction-related magmatism relies on indirect chemical and isotopic tracers and is hindered by the large range of potential melt sources (e.g., subducted oceanic crust and overlying chemical and clastic sediment, sub-arc lithospheric mantle, arc crust), whose composition may not be accurately known. There is also uncertainty about how crustal material is transferred from subducted lithosphere …
Migrating ship waste management from India to Finland : analysis of opportunities and risks in an industrial symbiosis of sustainable ship recycling
2015
Environmental protection and social wellbeing are significant segments of economic development. Market demand, legal directives, competitor existence and NGO interest together influence to manufacture in a cleaner and safer way and to abandon the traditional, often lethal working processes. Ship breaking is one of the most perilous industries where powerful states subordinate those countries where regulations can be bypassed for profit maximization. The unfavorable dependence arises from economic and technological arrears, and it results in environmental pollution, human rights violation and non-conformity with environmental, health and safety regulations. To improve environmental, health a…
Screening of halogenated aromatic compounds in some raw material lots for an aluminium recycling plant
2004
Four samples of scrap raw materials for an aluminium recycling plant were screened for the occurrence of persistent halogenated aromatic compounds. The samples contained waste from handling of electric and electronic plastics, filter dust from electronic crusher, cyclone dust from electronic crusher and light fluff from car shredder. In our screening analyses, brominated flame retardants were observed in all samples. Polybrominated diphenyl ethers (PBDE) were identified in all samples in amounts of 245–67450 ng/g. The major PBDE congeners found were decabromo- and pentabromodiphenyl ethers. 1,1-bis(2,4,6-tribromophenoxy)ethane, hexabromobenzene, ethyl-pentabromobenzene, tetrabromobisphenol-…
THE POSSIBILITY OF DISPOSING OF SPENT COFFEE GROUND WITH ENERGY RECYCLING
2015
The current policy of waste management requires, above all, a gradual reduction of waste amount and, to a larger extent, forces us to seek new methods of waste disposal. Recycling the energy contained in biomass waste is a more and more universally applied method of thermal converting. Biomass combustion allows saving fossil fuels which fits into sustainable development. This paper checks the possibility of using spent coffee ground (SCG) in energy recycling using a combustion process. This particular biomass type up to now has not been widely examined, which inclines to consider its usage as a potential additive to alternative fuels. In the study, we examined the quality of fuel, which was…
The use of calcined paper mill sludge as a chemical precipitant in the simultaneous removal of ammonium and phosphate : paper mill waste recycling an…
2020
Currently, recycling and re-use of materials is extremely important due to the diminishing of natural resources. The objective of the European Union’s circular economy strategy is to increase recycling and the use of industrial waste materials and side streams as secondary raw materials. In this study, a chemical precipitation method to simultaneously remove ammonium nitrogen and phosphate from the liquid phase of anaerobic digestate using calcined paper mill sludge was studied. Papermill sludge is a waste material that forms in the paper-making process. In addition, commercial calcium oxide (CaO) was used as a reference precipitant. The suitability of the formed precipitate’s composition f…
Investigating the Multi-Recyclability of Recycled Plastic-Modified Asphalt Mixtures
2023
Although the benefits of asphalt recycling have been scientifically proven and several best practices are being implemented, further research is required in specific and specialized areas. One of these circumstances is the recycling of Reclaimed Asphalt Pavements (RAPs) that contain asphalt modifiers such as elastomers and/or plastomers. Following the principles of the circular economy and considering the sustainability implications of asphalt mixtures, this paper deals with the multi-recyclability of asphalt mixtures containing 50% RAP with and without a recycled plastic asphalt modifier and rejuvenating agent. The recycled plastic asphalt modifier was made of hard recycled plastics and wa…