Industrial Scrap Research Articles

Improvement in classification accuracy of stainless steel alloys by laser-induced breakdown spectroscopy based on elemental intensity ratio analysis

Laser-induced breakdown spectroscopy (LIBS) is a useful technique for accurate sorting of metal scrap by chemical composition analysis. In this work, a method for intensity-ratio-based LIBS classification of stainless steel applicable to highly fluctuating LIBS signal conditions is proposed. The spectral line pairs for intensity ratio calculation are selected according to elemental concentration and upper levels of emission lines. It is demonstrated that the classification accuracy can be significantly improved from that of full-spectra principal component analysis or intensity-based analysis. The proposed method is considered to be suited to an industrial scrap sorting system that requires minimal maintenance and low system price.

Elastomeric Composites Containing SBR Industrial Scraps Devulcanized by Microwaves: Raw Material, Not a Trash

Environmental concerns about waste management systems have stimulated the search for technological and economical alternatives that introduce waste as raw material for production cycles. In this sense, this study aimed to develop and characterize styrene-butadiene rubber (SBR) composites that contain industrial rubber scraps devulcanized by microwaves (SBR-r) as a reinforcing filler. The scraps were ground under ambient conditions. From the obtained powder (SBR-r), composites were prepared, varying the exposure time of the powder to the microwaves (1, 2, and 3 min), as well as the SBR-r content. These composites were compared to a Reference sample (base formulation without SBR-r). The vulcanization parameters were determined by an oscillating disk rheometer. After vulcanization, the composites were characterized by mechanical properties (tensile and tear strength, and compression set). These properties were also evaluated after accelerated aging in an air oven and a UV chamber (ultraviolet light). The results indicated that as a result of increasing the exposure time of the waste to the microwaves, no significant influence in the composite properties was observed. Aged samples presented higher results as compared with the Reference sample (tensile strength up to 175% higher, tear strength up to 107% higher, and compression set up to 91% higher), which indicates the possibility of using these materials in technological applications, such as in the civil and automotive industries.

Characterization of the physical-mechanical and thermal behavior of a clay building unit designed with thermo-insulating attributes and a coffee cisco organic additive

This research is articulated from the clay framework as material wealth of the region of Norte de Santander, Colombia, and seeks to structure attributes of passive thermal cooling in a ceramic piece for low cost masonry type block cooked with physical, mechanical and thermals feasible characteristics for warm tropical weather conditions of 33 °C on average. This work is based on previous studies that explores the partitions structure morphology in Blocks H10 establishing a model of 6 horizontal cavities for low thermal conductivity and having oblique geometry partitions to interrupt heat conduction by direct thermal bridge inside of the constructive unit called Form-C, which is taken as the object of analysis, adding 5% organic coffee cisco additive in the 95% clay mixture to increase the porosity with a proportion that does not affect the deterioration of the mechanical properties and allow to optimize the thermal insulation capacity regarding to a traditional product. Methodologies: in the first phase, prototypes of Block H10 with Form-A are manufactured by extrusion at the laboratory level as a comparative witness of the properties of a standard piece and Form-C as a piece with thermo-insulating strategies to execute physical-ceramic, geometric evaluations of mechanical resistance and water absorption applying the Norma Técnica Colombiana 4017 for masonry units. In the second stage, simulations of temperature distribution and heat flow are prepared by finite element method in ANSYS R16 software to determine the incidence of the variables in the mixture on heat transfer. The results obtained from thermal simulations show an energy decrease of 1.5 °C on average in relation to Form-A. In conclusion, the use of agro industrial scraps and the implementation of passive design techniques in the ceramic piece generate added value in a product that can be industrialized with improvements in technological properties from a thermal efficiency perspective in construction ceramics.

Selective catalytic reduction of NO by NH3 on cerium modified faujasite zeolite prepared from aluminum scraps and industrial metasilicate

This work was devoted to the study of the selective catalytic reduction of NO by NH3 on calcined and hydrothermal treated cerium loaded zeolite catalysts. The parent faujasite zeolite Na–F (Si/Al = 1.32 and SBET = 749 m2/g) used as support for the preparation of the catalysts was obtained from industrial sodium metasilicate and aluminum scraps. As expected, the NO conversion increases with increasing the percentage of cerium in the structure of the faujasite zeolite. Total NO conversion into N2 is reached at 400 °C at a space velocity of 250 000 h−1. The high conversion is due to the redox shift between Ce3+/Ce4+ and the strong acid sites related to the rare earth present in the framework that is the key in SCR of NO process. Moreover, the highest loaded cerium catalyst retains almost its activity after hydrothermal treatment at 850 °C. This higher loading is desirable for both activity and stability provided that two stages of preparation are used to put the Ce ions in the sodalite cages.

Steel scrap added roller compacted concrete

The purpose of this paper is to investigate the benefits of using steel slag as an additive in Roller Compacted Concrete (RCC) which is a promising material can be used in streets, local roads, residential streets, high-volume roads, industrial access roads, airports...etc. The mechanical performances of steel scrap added reinforced cementitious composites produced with an industrial punch scrap. In specimen mixtures two types of scraps with diameters of 5 mm and 7 mm were used. The additive was mixed with 1%, 1.5% and 2% ratios by weight. Due to the results of the study, it was obtained that flexural strength properties of the specimens have increased up to 11%. In addition, freeze thaw effect of the specimens was investigated and found that 2% percent of scrap usage was given the best results.

Modern technologies for utilizing tobacco wastes

The problem of utilization or recycling industrial tobacco wastes is an important problem for tobacco industry. Economically preferable way for utilizing industrial tobacco wastes (tobacco scrap) is production smokeless products and hookah blends as wastes are utilized without special treatment. Monitoring of humidity and fractional composition of cut tobacco taken from tobacco rod/cigarette spoilage (tobacco scrap) is carried. Its long-term storage leads to increasing scrap and dust quantity. Researches on utilizing tobacco scrap for sniff and hookah blend production, which are considered to be less harmful compared to cigarettes, were carried. Chemical composition of American type tobacco and scrap was defined. Nicotine content varies from 0.9 to 2.4% and carbohydrates content – from 5.6 to 9.6%. Experimental samples of hookah blend were produced and their organoleptic and taste evaluation were carried. It was found that utilization of tobacco scrap is economically efficient for hookah blend production, as quality of final product made of leaf tobacco and tobacco scrap is similar. Experimental samples of sniff tobacco were produced in order to discover possibility of utilization industrial tobacco scrap for manufacturing this product. Consumer’s properties of sniff tobacco were evaluated by 100 points tasting protocol. This technology for sniff tobacco production from tobacco scrap allows manufacturing product of good quality, decreasing technological operations, rejecting stages of tobacco selection and its cutting and as the result decreasing cost of final product. The results of the research on utilizing tobacco scrap for hookah blend and sniff tobacco production proves optimality of recycling the tobacco wastes.

Challenges in the Recycling of Precious Metals

Precious metals from industrial scraps generated by manufacturing processes have been extensively recycled. For these recycles, it is necessary to ensure confidentiality when dealing with the scraps and to perform the recycling operation in an isolated lot with a high recovery ratio, short operation time, and low treatment cost. In recent years, three challenges have emerged in scrap recycling. The first is the decrease in the precious metal content in the scrap, owing to the substitution of precious metals with other non-ferrous metals. The second is the contamination of the scrap with metals that are not present in natural ores. These contaminations pose challenges in the extraction and purification of precious metals. The third challenge is the adherence to Japan’s environmental regulations, which have been tightened recently, restricting the continuous use of some chemicals such as nitric acid. In this report, some efforts of precious metal recycling companies to overcome these challenges are discussed.

Estudio calorimétrico con el uso de termopares en aislante hecho de mezclilla de desecho para viviendas en Saltillo, Coahuila

Introducción: En este artículo se presenta el desarrollo de un aislante térmico para edificios de uso habitacional hecho con material de desperdicio de las empresas maquiladoras de mezclilla asentadas en el municipio de Saltillo, en el estado de Coahuila, México. Se fabricó en forma de panel, procurando su funcionalidad, para que los habitadores de las viviendas puedan reducir el consumo de energía eléctrica mediante el uso de un sistema aislante que permita soportar los estragos del clima y genere mayor confort para el usuario.Método: Cada uno de los prototipos desarrollados fueron expuestos al calor producido por una serie de luminarias incandescentes y a lo largo de 22 horas se estuvo monitoreando el desempeño de cada muestra. Con la ayuda de termopares se obtuvieron las ganancias de calor sobre las caras exteriores (o expuestas a la fuente calórica) y las caras interiores, donde se registraron las temperaturas en las superficies de las mismas mediante el uso de una cámara termográfica.Resultados: Se observó que los diferentes tipos de páneles presentaron una variación en su eficiencia térmica de hasta un 66 %, en comparación con materiales como el BTC (Bloque de Tierra Comprimida) y un 75 % cotejados contra el block de concreto. Se escogió el panel de mejor desempeño, dependiendo de factores como el espesor de las muestras, la cantidad de materia prima que se utilizó y el tiempo de retardo térmico, que en el panel seleccionado fue 20 % más eficiente que en los prototipos restantes.Conclusión: El aislante desarrollado con mezclilla de desecho es capaz de mejorar las condiciones interiores de temperatura en una vivienda en Saltillo, ayudándola a ser más fresca en verano y cálida durante el invierno, además de consumir menos recursos energéticos debido a que es un material producido de desechos que no se aprovechan en ninguna otra área en la actualidad, hecho que contribuye a reducir la contaminación por el exceso de residuos sólidos industriales.

Waste steel scrap to nanostructured powder and superior compact through powder metallurgy: Powder generation, processing and characterization

The present paper reports fabrication of superior steel compact using nanostructured steel powder generated from industrial steel scrap. Extra low carbon and low carbon steel powders with size of submicron were generated from industrial waste by planetary milling for 5h. The milled powders are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and hardness. Finest particles are obtained after 3h of milling in both cases. In case of extra-low carbon steel, cold welding and agglomeration is observed after 5h of milling. However, in case of low carbon steel, no such phenomenon is visible after 5h of milling. The effect of ball to powder weight ratio (BPR) is studied using BPR of 12:1 and 6:1 for low carbon steel chips by milling for 3h. A higher yield of 94.29% is obtained when milling conducted at BPR 12:1 than 86.94% yield at BPR 6:1 after milling low carbon steel for 3h. Lower average particle size of 5–10μm is obtained when milling is carried out at BPR 12:1 than 15–20μm at BPR 6:1. In case of low carbon steel, % yield increases from 94.29% to 99.14% as milling time increases from 3 to 5h. Yttria free and 1wt% yttria dispersed both extra-low carbon and low carbon steel powders are cold compacted and conventionally sintered at 1100°C for 1h. Significant improvement in the hardness was achieved through addition of small amount of yttria with both the steel powder generated from the steel scrap.

Fused Deposition Modeling (FDM): An innovative technique aimed at reusing Lecce stone waste for industrial design and building applications

Lecce Stone is an attractive and appreciated natural material, as well as a non-renewable resource. For thousands of years people have extracted it from the Salento quarries for use as an ornamental, celebrative or building material. The production chain of this stone, from extraction through to the finished product, results in a great deal of scraps produced in both solid and muddy form. In recent decades a new attitude toward stone scraps has gradually taken hold, namely an eco-design approach. Already adopted by some companies, it consists of reusing industrial scraps to produce innovative manufacturing products. Nowadays, in fact, only a small percentage of Lecce Stone (LS) scraps is recycled and used as raw material in other fields, while a significant portion is taken to the landfill, as in the case of the scraps produced in laboratories by Apulian artisans.The aim of this paper is to design a novel composite biomaterial, based on Polylactic acid (PLA) and Lecce Stone (LS) scraps and verify its suitability for use by designers to produce original industrial and building products, thereby obtaining environmental advantages through this new practice, based on the Fused Deposition Modeling (FDM) technique.

Effect of Tungsten on Precious Metal Extraction During Processing of Radio-Electronic Scrap

An increase in demand for metal creates a requirement for finding new ways of supply. Toughening of ecological requirements for ore recovery necessitates ways for intensifying treatment processes with the aim of more complete extraction of economic components. In the forefront is secondary metallurgy technology making it possible to extract nonferrous and precious metals from waste. Ecological standards become an important condition for processing radio-electronic engineering scrap. Enrichment product compositions obtained from radio-electronic industry scrap are provided and results are described for melting radio-electronic scrap and dissolution of anodes prepared from this waste. The compositions of concentrates entering processing are provided. These compositions are analyzed in a Lab Center XRF-1800 x-ray fluorescence spectrometer. Anode potential measurements are given. The degree of tungsten oxidation in relation to temperature is analyzed. Kinetics of tungsten oxidation are studied and tungsten apparent oxidation activation energy is determined. It is concluded that tungsten may be a collector for gold. Tungsten oxidation is a required condition for reducing gold loss.

An experimental study on mechanical properties of fiber-reinforced concrete of energy piles

The technology of energy piles for heat storage involves turning the concrete piles buried beneath the ground into a part of the ground-source heat pump system and burying the heat-transfer tubes in the foundation piles, which are regarded as heat transfer wells. The heat transfer tubes are embedded in the concrete foundation piles, destroying the mechanical bearing capacity of the piles and damaging the safety of the buildings. Thus, considering the structural stability and the degree of heat transfer of concrete piles, as well as the selection of material for the foundation piles, the mixing ratio of the material of the energy piles is experimentally studied by the orthogonal method. The optimum mixing ratio of the energy pile is thus obtained. A concrete test block is used to conduct a static load test and splitting test to verify the mixing ratio of the concrete of the energy pile. The results show that steel fiber can be used to enhance the bearing capacity of the storage pile as a reinforcement material. Under a reasonable ratio, the reinforced pile can absolutely meet the original design requirements. Ordinary Portland cement or composite Portland cement can be used as cementitious materials for energy piles. Through an experiment, it is proved that the composite Portland cement can better meet the requirements of the concrete foundation piles than the cementitious material. As thermal conductivity materials, the addition of industrial graphite and scrap copper slag can improve the thermal conductivity of the pile, but it can also reduce the mechanical properties of the pile. It is necessary to control it in a certain range and not to add a large amount of graphite just to improve the thermal conductivity.

Industrial comminution of different Al scrap

The comminution of different industrial scale Al scrap, namely Al bus bar plates, turnings and chips, was investigated for its potential as processing route to fabricate powders for the powder metallurgy (PM) supply chain. The proposed processing route included a roughening stage to pre-process coarse Al scrap followed by a comminution stage to generate a wide distribution of pulverized granules and powders. The roughening process effectively refined the size and microstructure of the scrap particles but it also induced Fe contamination of the feedstocks. Quantification of the exogenous contamination accumulated during storage prior to comminution amounted to 20.79±0.06wt% for the pre-treated plates, 8.47±0.05wt% for the pre-treated turnings and 0.54±0.02wt% for the chips. The comminution process of each feedstock was characterized by their residence time which controlled the particle size distribution, morphology as well as the extent of Fe, Mn and Si contamination. Upon screening, the powder fraction smaller than 106μm of each pulverized feedstock was characterized and exhibited a passivation layer thickness and Al2O3 dispersoids content of ~9.8nm and 15.34±0.23wt% Al2O3 for the pre-treated plates, ~9.5nm and 10.07±0.18wt% Al2O3 for the pre-treated turnings and ~6.8nm and 2.13±0.11wt% Al2O3 for the chips, respectively. In addition, the presence of nanoscale grains was highlighted within all pulverized powders. Ultimately, the pulverized powders prepared from each scrap feedstock were found suitable for the PM supply chain provided process improvements were achieved.

Solvometallurgy: An Emerging Branch of Extractive Metallurgy

This position paper introduces the reader to the concept of solvometallurgy, the term used to describe the extraction of metals from ores, industrial process residues, production scrap, and urban waste using non-aqueous solutions. Here, non-aqueous is not used to imply anhydrous, but rather a low water content. The unit operations are as follows: solvent leaching; separation of the residue; purification of the leach solution by non-aqueous solvent extraction or non-aqueous ion exchange; and metal recovery by precipitation or electrolysis in non-aqueous electrolytes. Solvometallurgy is similar to hydrometallurgy in that both the branches of extractive metallurgy use low-temperature processes, but with solvometallurgy, there is no discrete water phase. Both branches use organic or inorganic solvents (excluding water in the case of solvometallurgy). However, for solvometallurgical processes to be sustainable, they must be based on green solvents, which means that all toxic or environmentally harmful solvents must be avoided. Solvometallurgy is complementary to pyrometallurgy and hydrometallurgy, but this new approach offers several advantages. First, the consumption of water is very limited, and so the generation of wastewater can be avoided. Second, the leaching and solvent extraction can be combined to form a single step, resulting in more simplified process flow sheets. Third, solvent leaching is often more selective than leaching with acidic aqueous solutions, leading to reduced acid consumption and fewer purification steps. Fourth, solvometallurgy is useful for the treatment of ores rich in soluble silica (e.g., eudialyte) because no silica gel is formed. In short, solvometallurgy is in a position to help develop the near-zero-waste metallurgical processes, and with levels of energy consumption that are much lower than those with the high-temperature processes. The Technology Readiness Level (TRL) of this emerging branch of extractive metallurgy is still low (TRL = 3–4), which is a disadvantage for short-term implementation, but offers a great opportunity for further research, development, and innovation.

Direct electrolytic refining of end-of-life industrial copper waste scraps for production of high purity copper powder

The end-of-life electric cables from both domestic and industrial sources offer an attractive resource of copper metal. In addition, copper wastes generated during fabrication of copper components remains another valuable source of recyclable copper. This work reports a simple, cost-effective and eco-friendly direct electrolytic refining using waste electrical copper wire scrap and copper plate rejects for producing the value added high purity copper powder. Suitable anode support system was applied in which compressed wire scrap or copper plate rejects were held to make anode for electrolytic cell. Electrolysis parameters like current density, acid concentration and copper ion concentration were varied to arrive at optimum condition. Results showed the energy consumption of 1.44 kW h/kg at 89% current efficiency for producing the copper powder, that consisted of >80% of–325 mesh size particles, from waste copper wire anodes. However, slightly lower energy consumption of 1.32 kW h/kg at 91% current efficiency was observed during production of copper powder from copper fabrication rejects. The copper powder thus produced was characterised by chemical analysis, XRD and optical microscope to examine the purity and morphology etc. and found suitable for powder metallurgical applications. Present investigations have established the potential utilisation of copper waste wire scrap and copper plate rejects for the production of value added high purity copper powder.

Estimates of global REE recycling potentials from NdFeB magnet material

Rare earth element (REE) containing neodymium-iron-boron (NdFeB) magnets play a major role in green technologies, including motor and generator applications. Recycling of REE from NdFeB magnets is expected to be beneficial from an environmental point of view compared to the production of magnets using primary REE currently practiced. This study gives a broad overview of global recycling potentials from end-of-life magnets from eleven different application groups and industrial scrap, quantified through dynamic material flow analysis. Data was obtained through a review of the literature, complemented by expert estimations. Recycling potentials achievable for REEs used in NdFeB magnets, namely neodymium (Nd), praseodymium (Pr), terbium (Tb) and dysprosium (Dy), were calculated for years 2020–2030, derived from two demand scenarios to reflect uncertainties in historic NdFeB demand figures and future demand development, taking into account the recent success in heavy REE reduction efforts. The most important NdFeB application groups in terms of recycling potentials are identified. The modelled scenarios show that between 18 and 22 percent of global light REE (Nd and Pr) and 20–23 percent of heavy (Dy and Tb) REE demand for use in NdFeB magnet production can be met by supply from secondary sources from end-of-life magnets and industrial scrap in years 2020, 25 and 30 (ranges of values for individual years and scenarios).

Intensification of ions of Chrome(vi) Removal during Waste Water Treatment with Magnetic Field

The authors investigated removal of ions of Chrome(VI) during waste water treatment with prompt industrial scrap from Engels Instrument Making Association "Signal". Intensification of this process with magnetic field was studied. The authors carried out macro-structural investigation of the prompt industrial scrap, and calculated efficiency of the waste water treatment.

Selective Extraction of Rare Earth Elements from Permanent Magnet Scraps with Membrane Solvent Extraction.

The rare earth elements (REEs) such as neodymium, praseodymium, and dysprosium were successfully recovered from commercial NdFeB magnets and industrial scrap magnets via membrane assisted solvent extraction (MSX). A hollow fiber membrane system was evaluated to extract REEs in a single step with the feed and strip solutions circulating continuously through the MSX system. The effects of several experimental variables on REE extraction such as flow rate, concentration of REEs in the feed solution, membrane configuration, and composition of acids were investigated with the MSX system. A multimembrane module configuration with REEs dissolved in aqueous nitric acid solutions showed high selectivity for REE extraction with no coextraction of non-REEs, whereas the use of aqueous hydrochloric acid solution resulted in coextraction of non-REEs due to the formation of chloroanions of non-REEs. The REE oxides were recovered from the strip solution through precipitation, drying, and annealing steps. The resulting REE oxides were characterized with XRD, SEM-EDX, and ICP-OES, demonstrating that the membrane assisted solvent extraction is capable of selectively recovering pure REEs from the industrial scrap magnets.

Development and Utilization of Circular Economy and Urban Mining - Chengdu City Based Renewable Resource Industry Survey

Along with the process of economic growth and urbanization, China has entered a peak period of electronic appliances and automotive industry products obsolescence. On one hand, municipal waste disposal is increasing and causing environmental pollution and damage; on the other hand, native mineral resources’ exhaustion has increased year by year along with exploitation difficulty and mineral resources import growth. Meanwhile, urban industrial scrap, aka "urban mines", does contain abundant of renewable resources, such as copper, iron, and aluminum. Therefore, based on the theory of circular economy, the exploitation of these "urban mines" is the key strategic industry of China’s "12th five-year plan". This paper is based on the survey of Chengdu city regeneration resources industry situation. We analyzed the current status of regeneration resources recycling industry in Chengdu city, finding problems such as the number of existing garbage collection stations inadequate for renewable resources, and processing technology out of date. Generally speaking, the renewable resources industry in Chengdu is under developed.

Recovery of carbon fibers from cured and uncured carbon fiber reinforced composites wastes and their use as feedstock for a new composite production

Cured and uncured scraps from manufacturing of epoxy based carbon fiber reinforced composites were treated with a pyrolytic process to provide, as solid residue, carbon fibers to be re‐used in new composites production. The industrial scraps were pyrolyzed at different temperatures in a 70 kg batch pilot plant and the pyrolysis products (gas, oil, and solid) were fully characterized. The solid residue (carbon fibers covered by a carbonaceous layer) was subjected to a further oxidative step at 500 and 600°C for different residence times to provide fibers devoid of any organic residue that did not volatilize during pyrolysis. The effects of both pyrolysis and oxidative process on the recovered fibers were evaluated by scanning electron microscopy and Raman Spectroscopy. The reinforcement behavior of pyrolyzed and pyrolyzed/oxidized chopped fibers, compared to virgin fibers, was tested in the production of new Chopped Carbon Fiber Reinforced Composites. The optimized double pyrolysis/oxidation process was found to provide fibers whose performance in the composites were comparable to the virgin ones. POLYM. COMPOS., 36:1084–1095, 2015. © 2015 Society of Plastics Engineers