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By V. K. Reddy Kallam, NEHA PANDEY, Sunil Kumar Tripathy, ARIJIT BISWAS

The study investigates SO2 leaching of low-grade ferruginous manganese ores to selectively recover manganese as MnSO4 and produce battery-grade electrolytic manganese dioxide (EMD). The effects of leaching parameters (duration, temperature, SO2 flow rate) on Mn recovery were studied. Under optimum conditions, 97.9% Mn recovery was achieved. The MnSO4 leach liquor was purified and used for electrowinning EMD with 88.01% purity and battery-active γ structure.

Apr 20, 2022

By D. R. Flynn

The recovery of nickel and cobalt from electromachining sludges in the form of relatively high-purity marketable products has been investigated. The investigation has shown that a series of metallurgical unit operations can be performed to recover nickel and cobalt from electromachining sludges in the form of al kal i nickel ic hydroxide and cobalt sulfate/cobal t metal, respectively. The recovery unit operations for nickel include high pH cyanide complexation, followed by oxidation and precipitation of alkali nickel hydroxide. The resultant filtrate can be treated for cobalt recovery by neutralization and acid baking to produce cobalt sulfate. The cobalt sulfate can then be treated for cobalt recovery by electrowinning. Results from laboratory bench scale test work are discussed in terms of appropriate operating conditions.

Jan 1, 1991

By Shigeru Ueda, Shin-ya Kitamura, Dong Jun Shin, Xu Gao

Steelmaking slag contains useful elements such as P and Mn. Generally, in the carbothermic reduction of slag, not only P but also Mn are reduced and a Fe–P–Mn alloy is formed. In this study, the possibility of the separation of Mn and P was investigated. A mixture of synthesized slag and graphite was heated at 1773 K, and the compositions of the separated slag and metal were analyzed. The results showed that with a decrease in basicity, the reduction of P was enhanced but that of Mn was suppressed. Thus, under an optimum condition, steelmaking slag was separated into a Fe–P alloy and a high MnO-containing slag. Although further investigation is necessary, the formed alloy and slag could be used as raw materials for fertilizers and Fe–Mn alloys, respectively. This paper elucidates the concept of this process and the results of the fundamental experiments.

Mar 1, 2018

Selective Recovery of Platinum from Cobalt-Rich Crust

Sep 13, 2010

By Hongmin Zhu, Kai Huang, Shuqiang Jiao

"Garlic peel was used as the raw material to synthesize the biosorbent for the selective recovery of precious metals from the acid chloride solution. Garlic peel is rich in carboxyl-, amino- and thiol-groups, has the potential of exhibiting high affinity to Au(III) when appropriate chemical modification process was employed. Here in the present study, the biosorbent was prepared by cross-linking garlic peel particles with concentrated sulfuric acid. Adsorption tests for mixing different metal ions such as Au(III), Fe(III), Cu(II), Ni(II) and Zn(II) from various concentrations of hydrochloric acid media indicated that Au(III) was selectively adsorbed on the cross-linked garlic peel gel over the other coexisting base metal ions investigated. The crosslinking mechanism and selective adsorption of Au(III) were also investigated briefly.IntroductionPrecious metals are quite popularly applied in the modern industries such as jewelry, electronics and electrical devices, catalysts in chemical industry, etc. While their high values, limited deposit and quite large demand in industry makes its recovery from the industrial wastes, typically e-wastes, quite necessary. Actually, many techniques have been developed to recycle and recover the precious metals from various industrial wastes effectively in last decades, but the cleaning and ecofriendly processes are still seriously scarce [1]. Taking into account of the typical recovery processes using cyanide lixiviant in the alkaline media, or aqua regia, followed by the further recovery process using activated carbon adsorption or cementation with zinc, iron or aluminum plate or powder, though they both are quite effective recovery processes, if considering the special requirements on safety and ecofriendliness for the modern hydrometallurgical processes, various improved or novel extraction processes are greatly demanded [2]. Recently, the biosorption technology applied to the recover precious metals in the hydrometallurgical process has become a concern [3,4]. Inoue’s research group made great progress in the recovery of precious metals such as gold, palladium and platinum from the e-wastes such as spent mobile phone by using biosorption from the hydrochloric acid media [5,6]. This new hydrometallurgical process exhibits the prominent advantages of being cost-effective for its short process, easy operation and near-zero emission. In the above recycling process for e-wastes treatment, the preparation of biosorbents is the key and backbone of the whole recovery process. For this purpose, they developed a series of suitable sorbents for precious metals recovery by using the tanning-based or cellulose-based biomass such as persimmon peel, grape peel, orange juicing residue, waste cotton, waste paper through the crosslinking process with concentrated sulfuric acid and relative chemical modification processes [7-10]. In the present study, we also applied this technique to prepare the biosorbent of precious metal uptaking by using garlic peels as the raw materials, and investigated the adsorption properties of such-obtained gel in the hydrochloric acid media."

Jan 1, 2012

By Hongxu Li, Zhaobo Liu, Zihan Zhao

A completely new process of selectively recovering Sc3+ without impurity of Fe3+ from Bayer red mud was developed. Prior to water leaching process, red mud needs to be digested and sulfated at a low temperature and subsequently roasted at a higher temperature for a period of time. During the roasting process, the products such as SO2, SO3 and H2SO4 molecules of thermal decomposition of sulfites including NaFe(SO4)2 and NaAl(SO4)2 could be recycled and reused as the raw materials of sulphuric acid. The leaching results indicate that roasting temperature and roasting time are the main constraint on selective leaching performance of scandium. As the sulfated red mud sample is roasted at 750 degrees C for 40 min and subjected to water leaching at 50 degrees C for 30 min, 53.0 wt% Sc3+, <1.0 wt% Fe3+, <0.3 wt% Si4+ and ~8.9 wt% Al3+ could be leaching out. Of note, the solid-liquid separation process is quite easy to be carried out.

Mar 1, 2017

By W. A. Rickelton, A. J. Robertson

The ability of triisobutylphosphine sulfides to selectively recover silver from acidic sulfate solutions containing zinc and copper is described. Selectivity is explained in terms of the concept of hard and son Lewis acids and bases. Silver is stripped from the solvent using a novel strip feed (thiosulfate salt), and the recovery of metallic silver from the strip liquor by electrolysis or cementation is suggested. The high selectivity of extraction for silver and the utility of the stripping reagent are demonstrated in continuous, countercurrent, mini-plant tests. Important reagent properties, such as hydrolytic stability and low aqueous solubility, are discussed.

Jan 1, 1988

The processes most likely to be adopted for beneficiating ores or concentrator streams containing a large proportion of particles finer than 10 um are froth flotation, selective flocculation, wet magnetic separation and selective leaching. Flotation will be made more efficient for very fine particles if ways can be found to selectively flocculate the valuable mineral beforehand (floc-flotation), to produce smaller bubbles and to reduce entrainment of ultrafine gangue. Schemes for selective flocculation have proved difficult to implement because of the delicate balance between surface forces (electrostatic, dispersion, hydrophobic) and hydrodynamic forces, that determines flocculation, and the changes which occur to particle surfaces through hydrolysis, oxidation-reduction and cross-contamination between minerals in aqueous suspensions. The search for a better understanding of selective adsorption of flotation collectors and flocculants continues and will be particularly important for the practical success of selective flocculation and selective magnetic coating.

Jan 1, 1986

By Brajendra Mishra, Mark L. Strauss, Gerard P. Martins

Europium is a critical material required for LED, florescent lamp, cell phone screen, and flat panel display production. This process recycling europium from waste lamp phosphors is an innovative method to supply europium. The selective reduction and precipitation method using sulfate precipitation is investigated to recover high-purity europium from yttrium-europium mixed solutions.

Mar 1, 2017

By Brajendra Mishra, Mark L. Strauss, Gerard P. Martins

Nearly the entire worldwide production of europium is recovered, as a minor constituent, from mining bastnäsite, monazite ore, or ion absorbing clays. However, this research indicates a process to recycle europium from waste lamp phosphors as a strategy meet the demand for europium. In this process, waste fluorescent lamp powder is retorted, sieved, leached, and precipitated to produce a mixed europium/yttrium rare earth oxide (REO). Europium is separated from yttrium by selectively reducing Eu(III) to Eu(II) using zinc powder and precipitating europium (II) sulfate from solution using sulfuric acid. Screening experiments were conducted observe the effect of pulp density, precipitation time, entrance pH, and stoichiometric ratio sulfate upon the grade and recovery of europium (II) sulfate. The best conditions to maximize grade and recovery of europium (II) sulfate were a 1 h precipitation time, 10 the stoichiometric ratio of sulfate, 100 g/L mixed REO, and the entrance pH equal to 3. The maximum grade of europium sulfate was 95.93%, and the maximum recovery was 73.32%.

Mar 1, 2018

By Bo Jiang, Jiusan Xiao, Hongmin Zhu, Kai Huang, Shuqiang Jiao

Carbothermal selective reduction of simulative titanium slag and various titanium raw materials were presented and SiO2 was found to be partially reduced, forming a series of Fe-Si alloys during the process. Thermodynamic analysis of the selective reduction between TiO2 and SiO2 was performed using HSC 6.0 software, then a series of equilibrium experiments were designed and presented. The activity of Si reduced from SiO2 was affected by the presence of Fe reduced from FeOx and the generation of Fe-Si alloys, promoting the reduction of SiO2 in the whole process. The results of experiment are in great accordance with the calculated data obtained from thermodynamic analysis.

Jan 1, 2016

By W. H. Cheung

Nickel and cobalt production relies heavily on the processing of nickel laterite ores; these ores contain the majority of known Ni and Co reserves, 80% and 90% ~ 95%, respectively. The Caron process is used to extract Ni and Co metals from low-grade nickel laterite ores (1% Ni and 0.1% Co). It involves selective reduction of NiO and CoO minerals followed by ammoniacal leaching. Despite low metal recoveries, this process continues to be technically and economically reliable and thus commercially important globally. However, keeping the Caron process cost-effective has been a challenge for industries because of increasing economic and environmental pressures. Although studies of the Caron process have been extensive, significant improvements in recoveries of industrial processes have not been forthcoming. Reported industrial metal recovery from high iron content ore is only 80% ~ 85% for Ni and only 40% ~ 45% for Co; recovery is even lower for ores rich in magnesium. The real difficulty here is that there is no complete understanding of and control over the complex series of reactions in the ore and in the leaching solution during processing. Achieving effective metal recoveries from the Caron will require control of the mineral transformations, which affect the activation of minerals by reduction. In this study, the effect of over-reduction was investigated, which superseded the effect of activation by lowering the activity of the minerals and thus metal dissolution. Reduction was carried out in a batch reduction apparatus with 1:1 and 1:2.5 CO/CO2 gas mixtures from temperatures of 500 ~ 700°C and residence times up to 60 minutes. The pre-reduced ores were leached using a standard ammoniacal leaching test. Thermodynamic analysis and possible effects of stable phase field on leaching was examined. The results suggest that control of over reduction effects are directly related to the mineral transformation and reduction conditions.

Jan 1, 2014

Selective Removal of Arsenic from Acid Mine Drainage Containing Ferrous Ion Using Sulfide Precipitation Method

Sep 13, 2010

By L. Hutton, S. W. Colley

"The release of soluble salts of base metals from acid mine pits and in the waste water from metal refiners is an avoidable source local pollution and contamination. Tightening of the regulations controlling natural resource extraction and industrial wastewater discharge is mandating the removal and recovery of metals from waste streams, and the remediation of contaminated sites. There is an economic incentive in recovering the valuable copper and nickel, as the value of the recovered metal can offset remediation costs and for high flow waste streams can be a source of income. Extraction of metals from waste streams by conventional Ion Exchange and chelation resins is widely practised, but has limitations on applicability in complex and dilute feeds due to the structure and properties of polymeric resin beads. Composite Advanced Ion Exchange (AIX) materials have been developed for the recovery and purification of base metals from base metal mining and metal processing industries. A silica-composite based resin has been developed for the selective extraction of copper from high iron containing feeds. This resin can be eluted with sulfuric acid yielding a copper stream suitable for return to solvent extraction or to electrowinning. We describe the development and application of the resin and process to two acid mine drain feeds of varying copper and iron concentrations, and show that the copper concentration can be considerably upgraded even at small scale with a final metal content of >95% copper.INTRODUCTIONWaste water with high sulphate concentrations, low pH and containing complex and variable mixtures of metals is an inevitable product in the mining, extraction and metal refining industries. One problematical water source is Acid Mine Drainage (AMD) which in addition to the metals of interest also contains a wide range of contaminating elements. Purge streams from metal refining are less complex in composition but contain significant quantities of the value metals. The typical treatment of such waste streams is treatment with lime to increase the pH of the water, precipitating the dissolved metals and sulphate as a sludge of mixed metal oxides/hydroxides and sulphates. The process is effective in producing a water stream that can be safely discharged but if there are significant concentrations of value metals such as copper, nickel, zinc then there can be a considerable loss of metal value."

Jan 1, 2016

By J. G. Stevens, S. W. Colley

"Selective separations of metals and ions in mineral extraction and refining are becoming more challenging as ore bodies become more complex and environmental pressures increase. The separation and containment of mercury produced in gold mining are a factor in the profitability and operability of mines. This paper will discuss the development and implementation of the Johnson Matthey HgFree selective mercury removal process. The process is designed to selectively recover co-leached mercury from either heap leach pregnant solutions at ambient temperature and low mercury concentrations, or electrowinning pregnant solutions at elevated temperature and high mercury concentration, without affecting gold or silver recovery. The process utilizes a highly selective adsorption-desorption step in which mercury is removed quantitatively by the HgFree adsorbent without adsorption of gold, silver or other metals present. Development of the original HgFree adsorbent has resulted in a process whereby mercury can be recovered as an inert salt and is never present as the free metal. The HgFree adsorbent can be regenerated and recycled in situ, and is capable of being reused multiple times. The overall process is compatible with existing gold mining and recovery practices and offers significant environmental and sustainability benefits, including reduction or elimination of the need to retort mercury with a subsequent reduction in potential mercury air emissions. Development of the HgFree adsorbent and process will be discussed along with a pilot operation at two operating mines.INTRODUCTIONMany gold ore bodies contain high concentrations of mercury which when extracted with cyanide, co-extract with the gold and other metals. This mercury is carried through the process with the gold, posing environmental and technical issues when it is separated from the doré. This paper describes a method to selectively adsorb mercury from the gold recovery circuit while it is in a soluble form, leaving gold to be processed as normal. The removal of mercury from the circuit eliminates the need for mercury retorting of doré and so reduces the potential environmental impact of fugitive emissions of elemental mercury."

Jan 1, 2016

By K. L. Gabby

Selective removal of mercury from cyanide leaching solutions while retaining silver has been a long-standing problem, due to the chemical similarity of mercury and silver. In order to be practical, a mercury removal process needs to be both highly selective and use inexpensive materials. This paper reports the use of zinc sulfide (ZnS) as a precipitant for mercury. The mercury cyanide complex (Hg(CN)4 2-) undergoes a replacement reaction with the zinc sulfide, forming insoluble HgS, while the silver cyanide complex (Ag(CN)2 -) remains in solution. Under appropriate conditions, the separation of mercury from silver is nearly quantitative, with close to 100% removal of mercury, while nearly none of the silver is precipitated.

By Reed M. Izatt

SuperLig® materials are capable of individually separating Rh, Pd, and/or Pt in highly purified form (99.95 to 99.99%) from a variety of chloride-based feed streams in a single stage operation. The hydrophillicity and associated kinetics of the supported materials allow for operation at relatively high flow rates of both loading and elution in a packed bed format. Pilot and commercial systems have been operated with Rh, Pd, and/or Pt present in the feed from single digit ppm (mg/l) to tens of g/l. A dual SuperLig® system for one pass Au(CN)2- separation followed by Cu and CN- recovery for CN- recycle has also been tested up to a pilot level,

Jan 1, 1999

By XUEWEN WANG, Xingming Wang, Xuehui Liu, Mingyu Wang

The Panzhihua titanium concentrate contains high contents impurity of Mg and Al, and it is difficult to prepare high grade titanium slag. To solve this problem, a sodium salt roasting-acid leaching process was proposed for removing the impurities in titanium concentrate. Na2CO3 and titanium concentrate were mixed with the proportion of 1:4, and then the mixture was roasted at 700 for 2h. After roasting, the calcine was leached with HCl solution. The experimental results showed that the removal rate of silicon and aluminum can reach more than 85% and 80%, respectively, at leaching temperature of 70 , leaching time of 4h, HCl addition of 5ml and liquid-solid ratio of 4:1.

Jan 1, 2016

By Hylton McWhinney, Doanh Tran, Jewel Andrew Gomes, George Irwin, Sameer Pallavkar, Md Islam, David Cocke, Mohammad Rafiqul Islam

"High-performance nickel-based nanocrystalline zinc oxide adsorbents have been prepared adjusting Ni/Zn mol ratio of 1 :5 by thermal decomposition, coprecipitation and sol-gel method for selective adsorption of thiophene in liquid hydrocarbon fuels at ambient temperature and pressure. To understand the nature of reactive adsorption of thiophene (C4H4S) on Ni/ZnO, the effect of preparation techniques, morphological and textural structure on the desulfurization activity was investigated. A model fuel (20 mL) consisting of pentane (C5H12) and thiophene was prepared and adsorption experiments were performed by a batch method under ambient conditions. The physicochemical behaviors of the fresh adsorbents were obtained using X-ray diffraction (XRD) with EDAX, scanning electron microscopy (SEM). The sulfur concentration in the mixture was monitored by UV-vis spectrophotometry. The adsorption reaction confirmed that ZnO played a crucial role in taking up S element to convert it into ZnS. The deposition of nickel on ZnO is an innovative approach which takes advantage of the selectivity of Ni towards S-species and the high adsorptive capacity of ZnO support.IntroductionLow temperature deep desulfurization of fuels via selective adsorption of sulfur compounds keeping coexisting aromatic hydrocarbons and olefins intact is receiving increasing attention in the research community worldwide in order to satisfy the upcoming environmental regulations and fuel specifications. The sulfur compounds in the transportation fuels is a matter of concern when global crude oil slate is becoming heavier and sourer and environmental restrictions on both the refining process and the refined products are becoming more stringent. According to the current refinery technologies, the sulfur content in refinery fuel is typically around 300-500 ppm by weight (ppmw) [1-3]. Starting in 2006, sulfur limits in highway diesel and gasoline were set to 15 ppm and 30 ppm, respectively. During combustion sulfur in the fuel are converted to toxic sulfur oxide (SOx) and contributes to air pollution and acid rains [ 4]."

Jan 1, 2011

By Ph. Cauwe

This paper presents the experience that NESA and MECHIM have gained about recovery of non ferrous and precious metals from complex sulfide materials. Processed materials are from natural deposits or metallurgical by-products or residues. Roasting of these materials is closely related to the pyro or hydrometallurgical processes used downstream of the roasting. Conditions of a first step of roasting the SELECTIVE ROASTING, are analyzed and explained. The roasted products so obtained are characterised by an extended elimination of volatile sulfides (AS, Bi, Sb, Sn, Pb, Hg, ?? ) and are readily available for the pyrometallurgical recovery of non ferrous and precious metals. After the SELECTIVE ROASTING, thanks to. the high porosity obtained in the "selective calcine", the SULFATE ROASTING is per-formed in excellent conditions. Hydrometallurgical tests performed for the final calcine show a high recovery of non ferrous and precious? metals and require only simple and well known processes. Many experimental and commercial data are given.

Jan 1, 1983