Copper and arsenic in acidic wastewater were separated by cascade sulfidation followed by replacement of arsenic in the precipitates by copper in the solution which was realized by recycling precipitates obtained in the first stage into the initial solution. The effects of time, temperature and sulfide dosage on copper and arsenic removal efficiency as well as the effects of solid to liquid ratio, time and temperature on replacement of arsenic by copper were investigated. With 20 mmol/L H2S at 50¡æ within 0.5 min, more than 80% copper and nearly 20% arsenic were precipitated. The separation efficiency of copper and arsenic was higher than 99% by the replacement reaction between As2S3 and copper ions when solid to liquid ratio was more than 10% at 20¡æ within 10 min. CuS was the main phases in precipitate in which copper content was 63.38% by weight.

The copper slag produced by Ausmelt Furnace contains a large scaled of valuable elements. In this paper, the copper in the slag was efficiently recovered by the process of flotation. The influences of cooling method, grinding fineness, and collector on beneficiation indexes were investigated. The structural and morphological properties of the slag were studied by SEM-EDS. And the results show that, applying the process of stage-grinding and stage-separation, simultaneously under the conditions of coarse grinding fineness at -0.074mm75%, regrinding fineness at -0.043mm85%, dosages of sodium sulphide, butyl xanthate and 2#oil for 95g/t, 90g/t, 85g/t, respectively, copper concentrate can be recovered from primary slag which includes 0.74% copper, and the grade is 16.11% with recovery of 69.90%. In addition, comprehensive utilization of the industrial electric furnace slag was studied, it indicated that the benefit of using flotation process to recover the copper from the slag is considerable.

The research into new technologies for the production of hydrogen was motivated by the growth in hydrogen’s demand. The production of hydrogen with membrane reactors is one of the most promising areas. Membrane reactors have a remarkable capacity to separate hydrogen through the semipermeable membrane, meanwhile it is produced. This mechanism allows shifting the chemical equilibrium towards reaction products in order to obtain higher conversions of the hydrocarbon feedstock, at lower temperatures, thereby increasing the energy efficiency of the conversion process.
The purpose of this work is to identify an optimized process for the recovery of the end-of-life membranes based on palladium and silver and prepared from substrates of stainless steel (since this particular configuration seems to be the most promising in terms of hydrogen recovery, purity and for a potential scale-up). In fact, these membranes have a prohibitive cost (up to 10,000 €/m2) that doesn’t allow them to be industrially employed. A potential recovery and recycling process of the main elements constituting the membrane can potentially contribute to a significant reduction in their unit production cost.
A hydrometallurgical process was then optimized in order to achieve the following main objectives: maximizing the dissolution of the damaged selective layer that is composed of precious metals (Pd-Ag) and keeping the metallic support intact, which will be retrieved and used for a new selective layer deposition.
An experimental campaign on laboratory scale was performed to test different leaching agents, reagents concentration and operating conditions (time and temperature of leaching) in order to define the optimal process conditions.
In particular, thiosulfate, thiourea and hydrochloric acid were tested for leaching but the best dissolution was achieved with nitric acid in an oxidizing environment. By this way, it was possible to obtain yields of palladium and silver dissolution of 42.6% and 72.5%, respectively, along with the simultaneous dissolution of the barrier of TiN (89.8%). After leaching tests the solid residues of membranes were analyzed by a Scanning Electron Microscope (SEM) to confirm the integrity of the metallic supports.
On the base of laboratory results a micropilot scale reactor was constructed allowing the external leaching of integer tubular membranes by pumping a thermostated solution with optimized composition. On the base of this microscale results and a fluido-dynamic analysis the scale up of the leaching reactor was performed (25 L).
A preliminary economic evaluation confirmed that such type of process could help to reduce of 50% the cost of the membrane per m2.

A novel economically process of extracting calcium from Electric Arc Furnace (EAF) slag in a microwave field by using recyclable NH4Cl solution and producing pure precipitate calcium carbonate was proposed. In order to improve the leaching rate of calcium, the calcium-bear phases in the EAF slag and its solubility in the system of NH3-NH4Cl-H2O were analyzed. As the dissolution of calcium from EAF slag is limited by the solubility of CaSiO3, the solubility behavior of CaSiO3 was studied according to the principles of simultaneous equilibrium and aqueous electronic charge neutrality in the system of Ca(II)-NH3-NH4Cl-H2O. The results show that the solubility of Ca(II) increases with the ammonium chloride concentration increasing and the highest solubility is about 0.5 mol/L, however, it decreases slightly with the ammonium hydroxide concentration increasing and the solubility is close to 0 mol/L in pure ammonium hydroxide solution. The equilibrium pH values of the leaching system are between 8.7 and 11.9. The forms of calcium presented in the system tend to be complexes instead of free ion with the increasing concentration of ammonium chloride and ammonium hydroxide.

The employment rate of solar photovoltaic (PV) panels for electric generation has increased significantly in recent years. The vast majority of these panels are currently sold in the residential market. As a result of such a recent and rapid diffusion of this new technology, there currently is a relatively low experience of the potential hazards associated with the decommissioning of PV panels. While recycling the materials used in PV panels would be advisable once they reach the end of their lifetime, this should be done in a way which is both environmentally sustainable and safe for human health. Crystalline silicon (monocrystalline and polycrystalline) is predominantly being used as a semiconductor in the industry at the moment, however, thin-film photovoltaic modules using cadmium telluride (CdTe) and amorphous silicon are becoming increasingly popular because of their lower production costs and higher efficiency. Two full-scale PV recycling processes have been implemented so far in Europe, however, none of them is completely automated and the discussion on which is best practice is still the topic of several research studies. The minimum targets of recovery and recycling required by the latest European Guideline (2012/19/EU) are achieved using either: (i) two-blade-rotors crushing followed by thermal treatment, or (ii) two-blade-rotors crushing followed by hammer crushing. Both processes reduce the initial PV panel to fine glass fractions, which can then be re-used as a raw material. However, these processes also create dust, which is harmful to humans if inhaled. For instance, silicosis is produced by inhalation of one of the forms of crystalline silica. It is defined as an occupational lung disease because it is usually diagnosed in combination with activities of sandblasting, quarrying, stone dressing, refractory manufacture or foundry work. Moreover, CdTe is classified as toxic by the related safety data sheets. This contribution aims to investigate the hazards associated with PV panels recycling, in order to lay the foundations for a systematic risk assessment procedure. We analyse the typical properties of the dust which are produced by the different PV panels recycling processes. We then investigate how this dust is transported by ventilation. In doing so, we use the results of a series of studies on the transport of heavy particles through a ventilated space, which were published recently. We quantify the fraction of particles of a mean diameter D<0.1 mm which are vented from the space as opposed to the fraction which sediment within the space. We also investigate how the concentration of the suspension of particles in air changes when the ventilation rate is changed. This will allow assessing the behavior of toxic dust and identifying the most appropriate safety measures, which may range from housekeeping to industrial ventilation. By the present work, we provide information on the recycling process and on the hazardous materials handled within it; we describe the transport of dust and particles in the air and identify the potential scenarios in which the safety of operators is compromised; finally, we define a range of safety measures.

The production of flue dusts is inherent in copper pyrometallurgy. These flue dusts are originated in the three types of furnaces used: flash, reverberatory and converters, and all have the same characteristics: a high content of copper accompanying with a myriad of other elements. This is because these dusts can be considered profitables (copper) and hazardous (arsenic, etc.), the above together with the nondesirable option of their recycling to the corresponding furnace, make of a necessity their treatment prior to their eventual dumping.
The present investigation deals with the treatment of one of these dusts, a converter dust, via hydrometallurgical treatment. The high copper content of the starting material (74 % copper in which 30% is metallic copper), makes any conventional leaching unusable, thus, an advanced option like thin layer leaching of the dust with nitric acid, followed by dissolution in water, leads to a pure copper solution.
However, the purity and copper concentration in the solution can be increased via solvent extraction, and a counter-current circuit using Acorga PT5050 dissolved in a kerosene diluent as extractant phase has been proved during 80 hours. The results indicated that a net copper gain of near 12 g/L copper is achieved and the existing aqueous solution can feed a copper electrowinning plant.

Waste diamond cutters are a kind of renewable resources with high value. In addition to diamond particles, the content of copper and zinc in some waste diamond cutters is up to 30%, respectively. Leaching copper and zinc from waste diamond cutters were carried out with ammonia-ammonium sulfate system using air as an oxidant. The influence of system variables on the copper and zinc recovery by leaching was investigated, such as reaction temperature, time, liquid-solid ratio, stirring speed, reactant concentration and air flow rate. The results show that the optimum leaching condition with ammonia-ammonium sulfate system was as follows: reaction temperature of 45¡aC, leaching time of 3h, liquid-solid ratio of 50:1, stirring speed of 200rpm, ammonia concentration of 4.0mol/L, ammonium sulfate concentration of 1.0mol/L and air flow rate of 0.2L/min. In the optimum leaching condition, the average leaching recovery of copper and zinc was up to 69.87% and 69.42%, respectively. Kinetic analysis of ammonia leaching shows that the leaching reaction for copper can be modeled with the shrinking core model and was controlled by the surface chemical reaction.

In this study, the effect of chemical interactions of materials used in ion flotation for the removal of Ni(II) ions from low concentration synthetic wastewater was studied. Sodium dodecyl sulfate (SDS) and ethylhexadecyldimethylammonium bromide (EHDABr) as collectors and methyl isobutyl carbonyl (MIBC) and Dowfroth250 as frothers were used. To investigate the effective parameters and interactions of them, 16 experiments including 6 level variables were performed by supporting DX7 software and on the bases of a 2-level factorial method. In the first step, the tests were conducted in a Hallimond tube. The result showed that collector of SDS and frother of Dowfroth 250 had appropriate interaction with each other at pH = 3.In the second step, optimal results from the first step were evaluated in a mechanical flotation cell. The removal of Ni(II) ions increased by increasing the time of flotation and they have a direct relation with the water removal. The kinetics study shows that the order and the rate of removal of the reaction do not follow any of the zero-order, first-order and second-order equations. The flotation rate curve on the removal of Ni(II) ions will divide the separation process to two stages, a fast flotation rate at the first stage and a slow flotation rate at the second stage. Ni(II) ions removal was obtained 88% at the best condition.This study showed that the use of ion flotation was a very effective method for Ni(II) ion removal from industrial wastewaters.

The iron and steel industry shares about 6~7% of global anthropogenic CO2 emissions. Meanwhile, significant volumes of waste slag, such as ladle furnace (LF) slag, are discharged. Recently, indirect aqueous carbonation process with minerals or basic oxides bearing solid wastes is one of the most promising options for CO2 sequestration. In this paper, the leaching behavior of Ca2+ from the waste slag using ammonium chloride solution and the pH values of leaching system were studied. The kinetic model and reaction mechanism of leaching process were also investigated. The results show that the leaching reaction of Ca2+ mainly occur at the initial stage of the reaction (0~30min), the extension of leaching time has little effect on Ca2+ leaching rate after leaching for 30min. Increasing the concentration of leachant and improving leaching temperature benefit to leach calcium from the waste slag. The leaching reaction of calcium in waste slag by ammonium chloride solution is found to be controlled by the diffusion of solid film.

Photovoltaic panels are the emerging technology converting solar radiation into electrical energy, which is expected to provide a fundamental contribution to the shift from traditional fossil fuels to renewable energy-based economies.
European community has extended regulations for the treatment of end-life electrical and electronic wastes in order to include the disposal of photovoltaic panels. The legislation currently established collection rates for photovoltaic modules up to 85% and recycling rates up to 80%.
In this work different kinds of panels (Si-based panels and CdTe panels) were treated by a process route made up of the following operations: mechanical pretreatment, sieving, and dedicated chemical treatment by solvent or acid of different fractions emerging from pretreatment. More specifically, after crushing, three fractions were obtained: a coarse fraction (>1 mm) requiring further chemical treatment by solvent in order to separate EVA-glued layers from glass fragments; an intermediate fraction (0.3-1 mm) of metal polluted glass requiring further treatment by acid leaching; a fine fraction (<0.3 mm) which could be further treated for precious metal recovery (mainly Ag and Cu). Coarse fractions (72% w/w) were treated by solvent giving recoverable glass fraction (56%w/w), plus metallic contacts, back sheets and EVA. All fractions below 1mm were sieved and chemically characterized for metal content. Intermediate fraction (0.3-1 mm), which are 13 %w/w, were fed to acid leaching in order to obtain another recoverable glass fraction eliminating metal impurities of Fe, Al and Zn. Fine fraction (< 0.3 mm) can be treated for extraction of precious metals (Cu and Ag).
The process route allowed to treat by the same scheme of operation mixed feed of Si based panels and Cd-Te panels with an overall mass recovery yield of 85%w/w.

A novel ceramic was prepared from red mud by designing its composition of the CaO-MgO (10wt.%) -SiO2-Al2O3 system. Linear shrinkage, bulk density, water absorption and bending strength of the ceramics were tested. Crystal phases and microstructure of raw materials and ceramic samples were respectively analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that all ceramic samples (replace of red mud for low quality clay from 10wt.%-30wt.%) have the similar thermal behavior, crystal phases and physical and mechanical properties, including low water absorption of about 0.07% and high blending strength of about 127.39MPa. Its sufficient densification during sintering process and generation of a great amount of pyroxene phase in ceramics would contribute to excellent mechanical properties.

Iron oxides were recycled from steelmaking slag in the forms of magnetically susceptible compounds by oxidation of molten steelmaking slag in water vapour. In this paper, confocal scanning laser microscope (CSLM) was used to observe the crystal precipitating behavior of the CaO-SiO2-FeO-MnO-MgO-Al2O3 melt during the cooling process. With the decrease of slag basicity (CaO/SiO2) from 2.0 to 1.0, the primary phase changed from Ca2SiO4 to Fe3O4. In addition, with the increase of slag basicity from 1.0 to 1.5 to 2.0, the recovery ratio of iron oxide in the slag first increase and then decrease.

A new method to recover zinc from high iron-bearing zinc calcines is developed. Zinc calcines was roasted to decompose zinc ferrite under the atmosphere of CO and CO2, then the roasted product was leached with alkaline solutions, in which zinc was selectively leached and iron was remained in leaching residues. Zinc extraction is as high as 98% after leaching in 5mol/L NaOH at 100oC for 60min. The leachate was purified using Na2S and Pb, Cu was removed as sulfide precipitates. The zinc was recovered from purified zinc pregnant solutions by pH adjustments using spent electrolyte as neutralizers. Nearly 99% of zinc were recovered as zinc hydroxide, and zinc oxide with high purity and good crystal structure was obtained from the zinc hydroxide after roasting at 250oC for 60min.

For many years, by-products of different metallurgical processes have not been considered as a potential source for metal recovery. The reason for this can be found in technological as well as economical aspects or simply because of missing know-how and the focus on only one product.
Since a few decades the situation has changed and by-products like slags, sludge and dust are taken more and more into account as a possible secondary resource. Nevertheless, recycling rates are still low and improvement of relevant processes or the development of new concepts is strongly required.
Especially by-products out of Zinc-, Copper- and Lead industry are well known to carry various base and minor metals which could be recovered, leading to a more efficient and sustainable metal production.
This paper gives an outline on the potential of such materials dumped as well as continuously produced ones. Besides an overview of the characteristics of the by-products regarding metal content and mineralogy, statistics on available amounts and valuable metals, possible to recover under economic considerations, are presented.
Finally, the availability of possible treatment concepts and processes or the necessity for new developments is discussed.
Summarizing, the paper tries to highlight, how more emphasis on the recycling of by-products out of metallurgical industry could have a positive effect on the metal supply, especially in countries with low primary resources, and how such an approach contributes to the principle of circular economy.

Adjusting mixture composition to fit a given Andreassen curve (i.e. size distribution parameter q is predefined) can be carried out by using commercial existing computer programs such as the EMMA (Elkem Materials Mixture Analyzer) software, developed by Elkem Materials (www.elkem.com/en/Concrete). EMMA uses the Andreassen model and allows us to design mixture of optimally-packed materials. In combination with extensive laboratory testing EMMA provides the basis for the accurate design of ultra-high strength concrete. The constraints considered during the estimation of the mixture proportions were:<br />- The maximum particle size considered as 4 mm. <br />- The resulting value of the q (Andreassen distribution parameter) of the examined mixtures should be as close as possible to the optimal value of 0.37. Values between 0.32 and 0.42 were considered acceptable. <br />Considering the above, several mixtures designs were created and theoretically examined for optimal packing by using EMMA software. Typical grain size distributions of the resulting mixtures shown in resulting graphs. The comparison of the obtained size distributions with the optimal curve (as defined by the Andreassen model) was done graphically, while the proportions of the mixture ingredients were chosen based on a recipe based on Outokumpu waste composition.

Inspired by the formation of sulfide ores under geothermal conditions, hydrothermal sulfidation (HS) using elemental sulfur as the sulfidizing agent is proposed as a potential candidate for metal recovery from nonferrous smelting residue. In this process, heavy metals contained in waste were initially converted into metal sulfides. Subsequently, the as-generated sulfides could be separated and further enriched by a flotation process. Finally, the reclaimed sulfides are sent back to smelters for metal smelting. As the recovery and stabilization of heavy metals can be realized in this process, HS has garnered much attention. In the present paper, an overall review of HS in the treatment of nonferrous smelting residue is given, including (1) the feasibility and fundamental of HS; (2) the process feature and dynamic mechanics of HS; (3) the experimental studies and results of HS in the treatment of typical nonferrous smelting residue; (4) specific influencing mechanism of calcium substance and (5) new development in hydrothermal sulfidation.

Climate change involves energy transitions in most of the industrial countries, leading simultaneously to a reduction of fossil energy consumption and to an increase of low carbon energies supply. In this coming energy mix, novel devices and systems are emerging for both production, conversion, storage, recovery and transportation of energy.
New technologies for energy need critical raw materials (CRM) also known as “vitamins for the high tech” to fulfill their specific functional properties. A crucial point is to work on the design of materials to components with low content of CRM or even without CRM at all that are replaced. For the end of life products and production waste, one has to pay attention to the recovery and valorization of CRM. These actions, their viability are strongly dependent on the raw materials costs and their fluctuations. The presentation will focus on several examples: Li-ion & Ni-MH batteries, Fuel cells, photovoltaic cells and permanent magnets. It will show how those components would enter in the circular economy.
Recycling covers several technical steps (waste & EoL preparation, sorting, mechanical/physical separation, recovery, and valorization) some of them will be illustrated using the above mentioned examples.
Finally, the presentation will show the different available instrument at the European level supporting research, development & innovation on recycling and more broadly on material efficiency all along the component life.

End of life batteries are potential source of secondary raw materials containing metals such as cobalt, manganese, nickel, lithium and rare earths. National regulations promote the development of innovative processes for the exploitation of such wastes. Pyrometallurgical processes currently used for the treatment of some kinds of batteries and/or battery fractions, cannot guarantee the complete recovery of metals and present significant drawbacks due to high investment costs, energy consumption and pollutant emission. Hydrometallurgical processes of battery fractions obtained by physical pretreatments offer a valid alternative to pyrometallurgy. In fact, these processes present great advantages in terms of investment, environmental impact and flexibility. This last point is of great relevance considering both the intrinsic heterogeneity of the battery waste category and the continuous changes in battery electrodic components. In this work experimental results were reported concerning the process development for lithium ion battery exploitation using real waste fractions emerging from pilot scale physical pretreatment. Automated mechanical pretreatment is a necessary step in battery exploitation allowing the separation of metal-containing electrodic materials from the other constituents of batteries. The purification section of the leach liquors obtained from electrodic materials was optimized taking into consideration the heterogeneity of real waste fractions obtained by automated physical pretreatment. Precipitation and solvent extraction operations were optimized giving as main products Co3O4 and Li2CO3. Due to the complexity of the process scheme, the limited amounts of collected wastes can compromise the economic feasibility of the recycling process. As a consequence all by-products have to be minimized and/or valorised for instance for the production of high value nanoproducts. In this view magnetic nanoferrites were synthetized using iron-containing sludge emerging from precipitation section and manganese-bearing solution emerging from solvent extraction. The same nanoparticles were used for refining the wastewaters emerging from lithium ion battery recycling process.

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