Green chemistry in mineral processing: chemical and physical methods to enhance the leaching of silver and the efficiency in cyanide consumption

2018 ◽  
Vol 90 (7) ◽  
pp. 1109-1120 ◽  
Author(s):  
Alejandro Alarcón ◽  
Carlos Segura ◽  
Carlos Gamarra ◽  
Juan Carlos F. Rodriguez-Reyes
Keyword(s):  
Green Chemistry ◽  
Mineral Processing ◽  
Metal Extraction ◽  
Complex Nature ◽  
Valuable Metals ◽  
Low Efficiency ◽  
Chemical Pretreatments ◽  
Extractive Economies ◽  
Cyanide Consumption ◽  
Silver Extraction

Abstract The leaching of valuable metals from mineral ores is the basis of several extractive economies around the world, but the strategies employed often need to rely on dangerous compounds such as cyanides. Due to the complex nature of most ores, leaching processes are slow and have a low efficiency in noble metal extraction, which is usually improved by fine-milling the mineral. In this manuscript, we consider this strategy, demonstrating that it may increase the amount of silver leaching, but at the expense of a higher consumption of cyanide, which renders the process inefficient (only 2% of consumed cyanide is employed to complex silver). The increase in the yield of the desired product without the smarter use of dangerous compounds is shown as a paradigm of the need to insert green chemistry principles in industrial processes. We further present the result of two potential strategies for greener mineral processing: the use of ultrasound to eliminate passivating layers formed during the leaching process and the use of chemical pretreatments to eliminate possible sources of passivation. These strategies can increase the amount of silver extraction and simultaneously increase the efficiency in cyanide consumption. The convenience of these pretreatments in the framework of the green chemistry principles, as well as the challenges towards their implementation at industrial scale, is discussed.

scholarly journals Sº and jarosite behavior during recovery of values from the direct leaching residue of sphalerite using cyanide and glycine

2021 ◽  
pp. 31-31
Author(s):  
N.G. Picazo-Rodríguez ◽  
F.R. Carrillo-Pedroza ◽  
Martínez Luévanos ◽  
M.J. Soria-Aguilar ◽  
I. Almaguer-Guzmán
Keyword(s):  
Hydrothermal Treatment ◽  
Elemental Sulfur ◽  
Extraction Process ◽  
Gold Extraction ◽  
Valuable Metals ◽  
Negative Effect ◽  
Leaching Residue ◽  
Direct Leaching ◽  
Cyanide Consumption ◽  
Silver Extraction

This paper reports the effect of the components of a direct leaching residue (jarosite and elemental sulfur), on the recovery of valuable metals such as gold and silver. Leaching media such as cyanide and mixtures of cyanide with glycine were used to recover the gold and silver from the residue; however, a low recovery of these metals was obtained. The above due to the negative effect of its components which cause problems in the extraction process such as encapsulation of silver (due to jarosite) and the formation of thiocyanate and re-precipitation of silver (due to sulfur). Various treatments prior to leaching were tested, finding that when the residue is desulfurized with perchlorethylene and subjected to an oxidizing alkaline hydrothermal treatment, the gold extraction increased from 39.73 to 88% and the silver extraction of 64.76 to 94.29%. Additionally, it was determined that when cyanide is assisted by glycine, the latter decreases the cyanide consumption by inhibition of the dissolution of iron and sulfur in cyanide.

scholarly journals Application of a cashew-based oxime in extracting Ni, Mn and Co from aqueous solution

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Chi M. Phan ◽  
Son A. Hoang ◽  
Son H. Vu ◽  
Hoang M. Nguyen ◽  
Cuong V. Nguyen ◽  
...  
Keyword(s):  
Organic Phase ◽  
Extraction Efficiency ◽  
Acidic Solution ◽  
Lithium Ion ◽  
Metal Extraction ◽  
Economic Potential ◽  
Cashew Nut ◽  
Valuable Metals ◽  
Loaded Organic Phase ◽  
Cashew Nut Shell

Abstract Background Cashew nut shell is a by-product of cashew (Anacardium occidentale) production, which is abundant in many developing countries. Cashew nut shell liquor (CNSL) contains a functional chemical, cardanol, which can be converted into a hydroxyoxime. The hydroxyoximes are expensive reagents for metal extraction. Methods CNSL-based oxime was synthesized and used to extract Ni, Co, and Mn from aqueous solutions. The extraction potential was compared against a commercial extractant (LIX 860N). Results All metals were successfully extracted with pH0.5 between 4 and 6. The loaded organic phase was subsequently stripped with an acidic solution. The extraction efficiency and pH0.5 of the CNSL-based extractant were similar to a commercial phenol-oxime extractant. The metals were stripped from the loaded organic phase with a recovery rate of 95% at a pH of 1. Conclusions Cashew-based cardanol can be used to economically produce an oxime in a simple process. The naturally-based oxime has the economic potential to sustainably recover valuable metals from spent lithium-ion batteries. Graphic abstract

Future of Mining, Mineral Processing and Metal Extraction Industry

2019 ◽  
Vol 72 (8) ◽  
pp. 2159-2177 ◽  
Author(s):  
Pradip ◽  
B. P. Gautham ◽  
Sreedhar Reddy ◽  
Venkataramana Runkana
Keyword(s):  
Mineral Processing ◽  
Metal Extraction

scholarly journals The Recovery of Valuable Metals from Ocean Polymetallic Nodules Using Solid-State Metalized Reduction Technology

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 20 ◽  
Author(s):  
Feng Zhao ◽  
Xunxiong Jiang ◽  
Shengdong Wang ◽  
Linyong Feng ◽  
Da Li
Keyword(s):  
Solid State ◽  
Magnetic Separation ◽  
Ferrous Metal ◽  
Mineral Resources ◽  
Metal Extraction ◽  
Metallic State ◽  
Ferrous Metals ◽  
Polymetallic Nodules ◽  
Valuable Metals ◽  
Pre Treatment

Ocean polymetallic nodules are oxide ores rich in Ni, Co, Cu, and Mn, which are valuable metals found in deep-sea mineral resources. Such non-ferrous metals do not exist in isolation, and producing concentrates using conventional mineral separation techniques is challenging without pre-treatment. We propose an effective, environmentally-friendly recovery technology combined with solid-state metalized reduction treatment and magnetic separation to recycle these metals from ocean polymetallic nodules. We conducted single-factor tests to investigate the effects of additives, anthracite dosage, duration, and reduction temperature on metal recovery and to obtain optimal operating parameters. We found that valuable metals in ocean polymetallic nodules may be selectively reduced to a metallic state. Only a fraction of Mn was reduced to metal. The reduced metals were recovered to concentrates using magnetic separation. More than 80% of these metals were concentrated to magnetic concentrates with mass ratios of 10–15%. The recovery rates of Ni, Co, Cu, Mn, and Fe in concentrates were optimum at 86.48%, 86.74%, 83.91%, 5.63%, and 91.46%, respectively, when using CaF2 4%, anthracite 7%, SiO2 dosage 5%, and FeS 6% at 1100 °C for 2.5 h. This approach to non-ferrous metal extraction using conventional hydrometallurgical processes could be a step toward practical industrial-scale techniques for the recovery of metals from polymetallic nodules.

Advancements in the treatment and processing of electronic waste with sustainability: a review of metal extraction and recovery technologies

2019 ◽  
Vol 21 (5) ◽  
pp. 919-936 ◽  
Author(s):  
Emily Hsu ◽  
Katayun Barmak ◽  
Alan C. West ◽  
Ah-Hyung A. Park
Keyword(s):  
Green Chemistry ◽  
Electronic Waste ◽  
Waste Recycling ◽  
Metal Recovery ◽  
Metal Extraction ◽  
Current Status

This review highlights the current status of e-waste recycling and provides insights on metal recovery from e-waste via green chemistry.

The Effect of pH on Bioleaching of Deerni Pyrite Roasting Residues as Magnetic Materials

2017 ◽  
Vol 730 ◽  
pp. 226-230 ◽  
Author(s):  
Xing Lan Cui ◽  
Hao En Zuo ◽  
Jian Kang Wen
Keyword(s):  
Sulfuric Acid ◽  
Magnetic Materials ◽  
Bacterial Growth ◽  
Culture Condition ◽  
Ph Value ◽  
Copper Deposit ◽  
Metal Extraction ◽  
Valuable Metal ◽  
Steel Making ◽  
Valuable Metals

The experiment focused on the Deerni pyrite roasting residues mainly made of magnetic materials such as hematite and magnetite in Qinghai Deerni Copper Deposit. The method of bioleaching sulfuric acid residue by bacteria was proposed for roasting residues desulfurization and valuable metal extraction. First of all, the study systematically performed multi-elements analysis, which provided scientific and technique basis for extraction of valuable metals. Subsequently, the effect of the pH value on the bacterial growth was investigated. The data revealed that pH at 1.2 was the optimum culture condition for the bacteria. The concentration of the bacteria at the best culture condition reached 8.5×107 cells/mL. Finally, the bioleaching experiments were performed to explore the ability of the NB bacteria to oxidize the Deerni pyrite roasting residues. The study demonstrated that the microorganism was able to effectively extract valuable metals such as copper and zinc. The total Fe and sulfur contents of the bioleaching residues account for 68.38% and 0.39%, respectively. The desulfurization effects are evident and bioleaching residues meet the requirements as magnetic materials in steel making industry.

scholarly journals Technospheric Mining of Mine Wastes: A Review of Applications and Challenges

2021 ◽  
Vol 2 (4) ◽  
pp. 686-706
Author(s):  
Bona Lim ◽  
Richard Diaz Alorro
Keyword(s):  
Environmental Sustainability ◽  
Mining Industry ◽  
Mineral Processing ◽  
Green Technology ◽  
Sustainable Chemistry ◽  
Mine Wastes ◽  
Secondary Sources ◽  
Valuable Metals ◽  
Development Data ◽  
Processing Techniques

The concept of mining or extracting valuable metals and minerals from technospheric stocks is referred to as technospheric mining. As potential secondary sources of valuable materials, mining these technospheric stocks can offer solutions to minimise the waste for final disposal and augment metals’ or minerals’ supply, and to abate environmental legacies brought by minerals’ extraction. Indeed, waste streams produced by the mining and mineral processing industry can cause long-term negative environmental legacies if not managed properly. There are thus strong incentives/drivers for the mining industry to recover and repurpose mine and mineral wastes since they contain valuable metals and materials that can generate different applications and new products. In this paper, technospheric mining of mine wastes and its application are reviewed, and the challenges that technospheric mining is facing as a newly suggested concept are presented. Unification of standards and policies on mine wastes and tailings as part of governance, along with the importance of research and development, data management, and effective communication between the industry and academia, are identified as necessary to progress technospheric mining to the next level. This review attempts to link technospheric mining to the promotion of environmental sustainability practices in the mining industry by incorporating green technology, sustainable chemistry, and eco-efficiency. We argue that developing environmentally friendly processes and green technology can ensure positive legacies from the mining industry. By presenting specific examples of the mine wastes, we show how the valuable metals or minerals they contain can be recovered using various metallurgical and mineral processing techniques to close the loop on waste in favour of a circular economy.

scholarly journals Functional role and therapeutic targeting of microRNAs in inflammatory bowel disease

2018 ◽  
Vol 314 (2) ◽  
pp. G256-G262 ◽  
Author(s):  
Artin Soroosh ◽  
Marina Koutsioumpa ◽  
Charalabos Pothoulakis ◽  
Dimitrios Iliopoulos
Keyword(s):  
Noncoding Rnas ◽  
Gastrointestinal Diseases ◽  
Complex Nature ◽  
Susceptibility Loci ◽  
Therapeutic Targeting ◽  
Small Noncoding Rnas ◽  
Therapeutic Value ◽  
Bowel Diseases ◽  
Inflammatory Bowel ◽  
Low Efficiency

Inflammatory bowel diseases (IBD) are chronic inflammatory gastrointestinal diseases, primarily consisting of ulcerative colitis and Crohn’s disease. The complex nature of the disease, as well as the limited therapeutic options characterized by low efficiency and major side effects, highlights the importance of developing novel strategies of therapeutic intervention in IBD. Susceptibility loci related to IBD are present only in a small percentage of IBD patients, implying that epigenetic modifications could influence the pathogenesis of the disease. MicroRNAs (miRNAs) are small noncoding RNAs that regulate multiple molecular pathways involved in IBD pathobiology. MiRNA inhibitors targeting the IBD-activated miRNAs could have therapeutic value for IBD patients. This review provides an overview of the recent advances in miRNA biology related to IBD pathogenesis and the pharmacological development of miRNA-based therapeutics.

scholarly journals Mineral Processing and Metal Extraction on the Lunar Surface - Challenges and Opportunities

2021 ◽  
pp. 1-27
Author(s):  
Matthew Shaw ◽  
Matthew Humbert ◽  
Geoffrey Brooks ◽  
Akbar Rhamdhani ◽  
Alan Duffy ◽  
...  
Keyword(s):  
Lunar Surface ◽  
Mineral Processing ◽  
Metal Extraction ◽  
Challenges And Opportunities

scholarly journals Extraction and separation of cadmium and nickel from two-phase aqueous systems by the method of liquid extraction, corresponding to the concept of "green chemistry"

2020 ◽  
Vol 62 (5) ◽  
pp. 58-63
Author(s):  
Roman D. Tangalychev ◽  
◽  
Nikolay B. Berezin ◽  
Zhanna V. Mezhevich ◽  
Sergey V. Buzov ◽  
...  
Keyword(s):  
Green Chemistry ◽  
Mutagenic Effect ◽  
Environmental Safety ◽  
Liquid Extraction ◽  
Process Conditions ◽  
Two Phase ◽  
Extraction And Separation ◽  
Extraction Behavior ◽  
Valuable Metals ◽  
Living Organisms

Extraction of valuable metals from chemical current sources allows not just to solve the problem of their disposal, but also to prevent environmental pollution. This approach is of particular importance in the case of the presence of toxic metals in chemical current sources, such as cadmium. Cadmium is known to have general toxic, mutagenic and teratogenic effects on living organisms. Nickel can cause allergic reactions and have a general toxic effect. According to some reports, nickel has a carcinogenic and mutagenic effect. The aim of the work is to obtain data on the extraction and separation of cadmium and nickel during the disposal of chemical current sources by liquid extraction, depending on the process conditions. The work obtained data on the separation, extraction of cadmium and nickel from Ni–Cd chemical current sources (CСS) using an two-phase aqueous extraction system consisting of polyethylene glycol (PEO-1500), a phase-forming salt of Na2SO4 and water. The extraction behavior of metals and their separation into lower and upper phases using an extractant, potassium iodide, was studied. The maximum recovery of Cd (99.2 ± 1)% and Ni (89.4 ± 1)% is achieved by leaching the batteries with HCl under the following conditions: KI concentration of 3 g/l, dilution coefficient of the CСS solution is 35. The liquid extraction method used in this work has been shown to be effective for the separation of the metals in question and has an advantage in terms of environmental safety. This extraction technique corresponds to the concept of "green chemistry".

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