Ammoniacal leaching and recovery of copper from alloyed low-grade e-waste (original) (raw)
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Development of a Process for Copper Recovering from Galvanic Sludges
Galvanic coating processes are based on metal plating baths and are responsible for the production of large amounts of wastewaters. Subsequent physical-chemical treatment of the wastewaters generates solid wastes called galvanic sludges. These sludges have a hazardous character and are often disposed, mainly on landfills, without any economical or environmental benefits. The development of alternatives and viable ways to reduce the environmental impact and recover the valuable metals contained in those sludges such as copper, chromium, nickel or zinc, which content might reach 30% (wt.%, dry weight) are of utmost importance. The present work has been developed in the aim of the project VALMETAIS and proposes a hydrometallurgical process for copper recovery from galvanic sludges produced by Ni/Cr plating plants. This procedure has been developed on laboratory scale and is based on leaching of sludges in sulphuric acid solution followed by copper cementation step, using iron scrap as a precipitating agent. The sludge has been characterized for its chemical and physical properties. Chemical analysis showed a copper concentration of more than 10% (dry base). Preliminary leaching tests in both sulphuric acid and ammoniacal media were performed in order to determine the best operating conditions for this step of the process and to assure the best metal recovery conditions in subsequent separation methods. Sulphuric acid yielded much higher metal ion dissolution when compared with ammoniacal leaching. Optimal experimental leaching parameters were defined as follows: sulphuric acid solution 100 g/l, a solid to liquid ratio of 1:10, stirring speed of 400 rpm at room temperature and under atmospheric pressure. It was found that metals dissolution was almost complete in 30 minutes of reaction time. Extraction rates of 99% for Cu and Ni were obtained under the leaching conditions above mentioned. The solid residue separated from the leaching solution is mostly constituted by gypsum (CaSO 4), and presents a metal content below 1%. The subsequent extraction of cooper from the obtained solution is achieved by a cementation step with iron scrap. Copper precipitation was performed at a pH of 2 which was achieved through adding new sludge to the filtered leaching solution. Such pH level led to insignificant precipitation of other metals present in the leaching solution, namely chromium. The recovery rate of copper is about 90% and the purity grade of the resulting copper cement enables its application as a commercial product.
Waste Management, 2003
In the present paper, a study on laboratory scale to perform a treatment for valuable metals recovery from electronic and galvanic industrial wastes, is reported. The characterisation of the waste, performed by XRD, SEM, EDX and chemical analysis, showed a high metals content in the sludge, such as Cu, Ni, Mn, Pb, Sn, W. A leaching process, coupled by electrowinning, is then proposed in order to reduce the volume of the waste material and to recover selectively valuable metals, such as Cu and Ni. During the leaching step, carried out by using H 2 SO 4 , several factors were investigated (acid concentration, temperature and time of treatment). The leached liquor has been successfully treated with an electrowinning process, to recover copper and nickel. The copper and nickel depositions, were performed in acid and alkaline conditions, respectively. The Faraday yield was of about 95%. The energy consumption was 2.13 and 4.43 kWh per kg of copper and nickel recovered, respectively. At the end of the process, about 94-99% of the initial content of Cu and Ni was recovered at the cathode. The experimental results obtained, showed the technical feasibility of the process. #
Copper Recovery Originating from Galvanic Industry
2002
Environmental regulations limit the presence of copper in the wastewater from industries to 3 mg/l; furthermore, copper is a rather expensive commodity. Consequently, recovery of this metal is both necessary and attractive. Electrowining techniques are commonly used to recover copper, but it cannot be used when the streams contain hydrocarbons such as the waste stream, Multibond, from company A. As a result, this company is force to send their waste stream abroad for treatment paying 1.32 Euro/kg of waste. The present project aims to recover copper via a hydrothermal process in the form of (99% pure) copper metal powder that can be sold to scrap industries in the area. The copper reduction will be achieved by combining a copper sulphate solution (copper II) waste stream and a carbohydrate waste stream under 12 bar and 185 o C in a Kenics static mixer. The accessibility and the low or no-price for the feedstocks, make this design even more attractive. The copper reduction plant consists mainly of two units: reaction and separation. Thus making it a very simple process. Furthermore, the recovery is >99% copper. This process has already been made a reality in countries such as Chile where copper is abundant and the main export commodity. Currently new sites for this process are being developed and have been patented around the world.
Electroleaching of Copper Waste with Recovery of Copper by Electrodialysis
A new process to leach and recover copper from solid waste using electric fields was designed. The leaching with electro migration is presented as an alternative to traditional leaching. Preliminary data indicate that the copper ion migration is facilitated by using the electrical potential difference; therefore applying a potential difference in the processes of leaching facilitates the removal of copper. This is especially useful when mineral concentrations are very low. Different phenomena associated with transport of copper in solution are studied to generate a model able predict the state of the copper ion concentration in time. A kinetic model for the process was developed and fitted very well the experimental data.
Recovery of valuable metals from mining and mineral processing waste
E3S Web of Conferences, 2020
Ammonia-thiosulfate-copper leaching, aided by a direct current electrochemical impact, is proposed to extract gold (Au), silver (Ag) and copper (Cu) from old flotation tailings mixed with waste rock. Over 80 % of Au available in the waste material and over 75 % of Cu and Ag were extracted into the pregnant leach solution (PLS) at room temperature. Electrowinning from that PLS recovered around 92 % of Au and Cu, and about 87 % of Ag in the cathode deposit that is suitable for further metallurgical refining. The results are better, compared to leaching in the same system but without electrochemical impact and at air addition. The proposed direct current aided method is promising and more environmentally friendly compared to cyanide and even to sodium thiosulfate leaching.
Recovery of Copper Metal through Reprocessing of Residues from a Hydrometallurgical Plant
Asian Journal of Engineering and Technology, 2017
The Chemical of Africa (CHEMAF) is a hydrometallurgical plant operated in Katanga since 2001. It produces copper metal using a process comprising the sulphuric acid leaching of copper-cobalt oxide ores under reducing conditions (Na 2 S 2 O 5 or SO 2 ) followed by the leach liquor purification by solvent extraction (SX) and electrowinning of copper. The leach liquor is recovered during the thickening of pulps from the leaching section and the scavenging of residues by washing in the counter-current decanters (CCD). The process residues were anciently dumped near the plant. With the increase in the run of mine (ROM) ores sulphide minerals content related to changes in the Kalukuluku deposit mineralogy and considering that the storage of residues may result in toxic pollutants release to the environment, their reprocessing is gaining the ground as the best option. The present research aims at recovering copper metal from residues (2.01% Cu and 0.32% Co) through their reprocessing based...
Metals, 2020
The metal-containing sludge generated from the printed circuit boards (PCBs) manufacturing has been recycled as a secondary resource of copper (Cu) rather than being treated as a hazardous solid waste. However, it should consider the complexity of processing and using of oxidizing or precipitation agents to dissolve and separate Cu from other impurities, especially iron (Fe). This study has combined the dissolution and separation step in one stage by integrated acid leaching and electrodeposition to simplify the recovery process, while maintaining the high efficiency of separation. The chemistry of acid leaching and electrodeposition of the metals demonstrated that the metals (Cu and Fe) in the sludge sample were dissolved in the H2SO4 electrolyte, and Cu could be selectively deposited on the cathode based on the different potential conditions to reduce it on the cathode. The important factors affecting the deposition of Cu were investigated, finding the optimal conditions (current ...
Study on Recycling of Galvanic Sludge containing Copper for Pure CopperProduction
Journal of Material Sciences & Engineering, 2019
Metal containing waste sludge from electronic industrial has been rapidly accumulating due to the surge of global demands for electronic components. This study looks into the feasibility of recycling copper from galvanic waste through hydrometallurgy combining with electrometallurgy process. The parameters of copper selective leaching including types of leaching solution, acid concentrations, and liquid-solid ratios were systematically studied. The optimum selective leaching conditions were 1 M and 2 M sulfuric acid with 24 h leaching duration, 100/1000 g/cc solid-liquid ratio offering copper leach recovery of 42,540 and 45,850 mg/l, respectively. Copper purification was successfully obtained from electrolytic refining process. The effects of electrolysis voltage to the amount and purity of copper cathode were studied. It was found that the optimum parameters for copper purification were using 2 M sulfuric acid with electrolytic voltage of 2.2 V. Under these conditions, the recovery...
The effect of leaching time and ammonia concentration on the atmospheric leaching of copper
The effects of ammonia concentration and leaching time were investigated to determine the optimum leaching conditions. The experiments were conducted in a leaching cell submerged in a water bath, with ammonia concentrations of 1.5 M, 2.0 M, 2.5 M and 3.0 M and varying leaching time from 0 to 300 min. Ni-Cu matte containing 23% by mass Cu was used in this experimental study. Increase in the concentration of the lixiviant was found to increase recovery when leaching for 130 minutes, with a recovery of 32.86% Cu using 3 M solution of ammonia. An increase in the leaching time resulted in more copper being leached for all lixiviant concentrations. However, leaching with 2 M ammonia solution gave a higher yield of copper compared to higher concentrations. This anomaly could be a result of cementation; Cu is displaced by Ni as Ni is a more electronegative metal than Cu .It was found that at higher concentrations more nickel was extracted.
The Journal of Solid Waste Technology and Management, 2017
In an experimental study design with laboratory analysis, printed circuit boards (5 kg) of obsolete television were ground and sieved to obtain 2 mm particle size. Chemical leaching of copper using different concentrations of nitric acid (1 mol, 3 mol, 5 mol and 7 mol) was carried out at varying time intervals (0 h, 12 h, 24 h and 48 h). Leachate obtained was subjected to electrolysis to recover copper using a prototype electrolytic cell designed and fabricated locally. Bioleaching was carried out through composting process for four weeks using market wastes and cow dung under mesophilic conditions. Chemical leaching yielded higher copper (236 187.6 ± 0.4 mg•kg-1) than that leached biologically (74.4 ± 0.1 mg•kg-1). Electrolytic extraction showed that the mean weight of copper deposited at 1 Mol acid extraction (683.3 ± 2.6 mg) was significantly higher than that deposited at 3 mol concentration of electrolyte (366.7 ± 2.6 mg). Also, copper extracted electrolytically from chemical leachate (366.7 ± 2.6 mg) was higher than that extracted from bioleachate (36.8 ± 1.8 mg) at 3 mol of electrolyte. Bioleaching is a very slow process and the yield depends on method of leaching, current, voltage, electrolyte concentration, time and electrode types. These factors play an important role in electrolytic recovery of copper from e-wastes.