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By L. Evrard, S. Brouwer, E. Bosly, E. Boydens

"A partial desulfurization roasting process has been tested on a typical copper-zinc sulfide concentrate in a Nichols Herreshoff monohearth pilot furnace whereby the su!fµr is partially removed and iron is to a certain degree preferentially oxidized. The phase changes that occur in the particles during selective roasting at 650°C and 800°C over a range of residence times were investigated by the use of chemical analysis, optical microscopy, X-ray diffraction and electron microprobe analyses. The purpose of this work was to get an insight into the mineral assemblages formed by controlled oxidation roasting and to evaluate if this non traditional approach could be afterwards used to recover zinc, copper and iron by a physical separation method. IntroductionThere has been considerable interest over the years in improving extraction and processing procedures for recovering non ferrous metals especially from polymetallic ores containing copper, lead, zinc and iron sulfides with very fine intergrown phases. Complex sulfide ores, which represent considerable reserves and resources in copper, lead and zinc, as well as precious metals and sulfur, are difficult to treat by conventional physical processes, leading to impure concentrates at low metal recovery. Some methods that can be used to treat such ores were described by G. Barbery (1). Various metallurgical routes generally combining pyro- and hydrometallurgical methods have been explored to develop new processes to recover the metals from zinc-bearing sulfidic ores and concentrates (2, 3, 4). The feasibility of partitioning complex sulfide minerals to simpler phases in order to improve selective extraction of mineral constituents has also been investigated (5)."

Jan 1, 1999

By Tibor Zoltai

Asbestos is a generic term for industrially useful fibers recovered from exploitable deposits of the asbestiform varieties of five silicate minerals: chrysotile, anthophyllite, actinolite-tremolite, cummingtonite-grunerite, and riebeckite. Asbestos and asbestiformm fibers of some other minerals are known to be carcinogenic. Minerals crystallized in the asbestiform habit are characterized by unique properties (morphology, strength and flexibility, physical and chemical durability, and defect-free surface structures). The key to the unusual properties, and health effects, of asbestifarm fibers appears to be in their unusual surface structure. In contrast, non-asbestiform crystals of the same minerals, including the five so-called asbestos minerals do not have these properties and are not carcinogenic (1, 2).

Jan 1, 1989

By M. K. Mohan

During the processing of metals like Cu, Ni, Co, large quantities of solutions, which contain co- products such as Sb, Cd, Pb etc. are generated. These solutions if processed to recover the metals help in conservation of metals as well as environment preservation. The present study was taken up to recover antimony from process solutions using zeolites. The effect of pH of the solution, time and type of zeolite viz., chabazite, mordenite, erionite and clinoptilolite on the sorption of antimony was investigated. Rate of sorption increases with pH and about 77-pct. antimony sorption was observed with chabazite at a pH of 6. Optimal conditions were established for the maximum recovery of antimony fiom process solutions. The mechanism of sorption for Sb was proposed in terms of adsorption and intraparticle diffusion. The calculated adsorption constants from Langmuir and Freundlich equations indicated that the adsorption of antimony on chabazite was strong.

Jan 1, 1999

By D. Neuschiltz, M. Witthaut, R. Cremer

"Metastable (Ti,Al)N coatings with fee structure have been shown to exhibit superior performance as compared to TiN under conditions of wear at elevated temperatures due to their better oxidation resistance and hardness. The oxidation resistance of these coatings increases significantly with increasing Al-content. However, the deposition of (Ti,Al)N films with Ti/ Al ratios below about 30/70 leads to a hexagonal structure which is not suitable for tribological coatings. Only little is known about the location of the cubic to hexagonal phase transition and hence about the optimum composition of (Ti,Al)N hard coatings.To determine the position of this transition, Tii-xAlxN films with different Ti/Al ratios were deposited on high speed steel at substrate temperatures between 100 and 700 °C by means of reactive MSIP. The composition of the films was determined by electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS), the crystallographic structure by thin film X-ray diffraction (XRD).It could be shown that in case of deposition temperatures of 300-700 °C a two-phase region exists in the metastable TiN-AlN phase diagram, which expands with increasing temperature, wheras at 100 °C substrate temperature no two-phase region was observed. But in opposition to the phase diagram known from literature, which is based on thermodynamic estimations, the detected two-phase region is narrow for typical PVD temperatures, thus allowing the deposition of cubic single-phase Al-rich (Ti,Al)N hardcoatings for tribological applications. Based on these results, a new Ti1-xAlxN film with x = 0.62 has been developed, which showed an increase of oxidation resistance by a factor of 4."

Jan 1, 1998

By J. V. Happ

The investigation reported in this paper was prompted by the belief that vacuum processing of copper mattes could provide significant advancement to present-day copper smelting and converting technology. Specifically, vacuum distillation of copper mattes in a unit such as the R.H. vessel used in vacuum degassing of steel, can lead to improvements in: converter flue-gas-cleaning system, purity of acid (or liquid SO2), aisle hygiene, purity of electrorefined copper and smelter flexibility. In the study conducted, removal of Volatile impurities (arsenic, antimony, bismuth, lead and zinc) from liquid mattes, by vacuum distillation in a laboratory-scale equipment was performed. The conditions investigated covered a temperature range of 1123-1223K, absolute pressure of 6.5-0.5kPa (50 - 3 mm Hg) and with bleed gas consisting either of pure oxygen or argon. Six matte samples (four U.S. and two foreign) were tested. Under the "best" conditions arsenic and antimony were reduced to << 0.01% in the product matte. The removal of bismuth, lead and zinc was variable and appeared to be influenced by the matte composition of the sample. As might be expected, the rates of distillation of the various species were increased at higher temperatures and lower absolute pressures. The influence of a small flow rate of gas (02 or Ar) over the melt did not have a signifi¬cant influence on the extent of impurity removal. The magnetite content of the matte was reduced by up to 30% during vacuum treatment and was favored by a low partial pressure of oxygen over the melt. Substantial amounts of sulfur were also evaporated and an, overall increase in copper grade of the matte was realized. The paper concludes with an evaluation of industrial aspects of the process as applied to conventional smelters.

Jan 1, 1983

By K. J. Cathro

A hydrometallurgical process is described for the recovery of copper from chalcopyrite concentrates. The process is based on a cupric chloride leach, the concentrate having first been "activated" by heating it with sulphur at a temperature near 400°C. This activation process converts most of the iron of the chalcopyrite to pyrite, which is insoluble in the cupric chloride leachant. The copper is converted to the mineral idaite, which dissolves readily in hot cupric chloride: at 106°C, 98% of the copper is extracted in a three-stage countercurrent leach, the leaching tirqe being 1 hour per stage. The sulphur of the chalcopyrite appears as elemental sulphur, which is recycled for the activation of further concentrate, the final leach residue consisting of pyrite, plus the gangue present in the original concentrate. The copper extracted can be recovered by electrowinning, using a diaphragm cell. Current efficiency (one-electron basis) is about 70% but the cell voltage is only about 1 V, so that power consumption is three times lower than for the conventional sulphate electrowinning process. The leachant is simultaneously regenerated in the anode compartment. The behaviour of minor elements in the concentrate has also been studied.

Jan 1, 1976

By F. F. Aplan, G. Simkovich

"A review is given of the effects of solid state point imperfections upon a number of mineral benefication processes and a metal extraction process. It has been found in numerous flotation studies that small amounts of aliovalent impurities (dopants) in binary compounds may show major effects upon flotation behavior. Both semiconducting and ionic conducting compounds are affected. These effects are also seen in hydrometallurgical studies as well as in electrostatic operations. Additionally, de-copperization of lead melts appears to be strongly influenced by similar defects. It is hypothesized that the effects observed in these studies are present in actual operations and should be considered in designing processes. A few speculations concerning future efforts are advanced. IntroductionImperfections [point (e.g., vacancies, interstials, quasi-free electrons, electron holes, impurity ions), line (e.g., dislocations), two dimensional (e.g., grain boundaries) and three dimensional (e.g., 2nd phases) defects] are generally present in solid materials and these imperfections may, and often do, have important effects upon a variety of properties and processes. In general, one may, in most cases, attain elimination of three dimensional defects by a separation process of one type or another (e.g., gravity, electrostatic, magnetic, flotation, hydrometallurgical etc.,). Thus, this type of defect has rarely been investigated in a systematic fashion. Two dimensional defects are always present in non-single crystal materials but have also escaped systematic studies in processes primarily because the control of such defects is not easily attained. Line defects are non-equilibrium entities which are present in ill-defined quantities so that they present a variable that cannot be easily controlled although through careful systematic experiments one can attain some reproducible relations pertaining to this type of defect.Contrary to the lack of studies concerned with the effects of 1, 2 and 3 dimensional types of defects there has been some activity concerned with point defects and their effects upon a number of mineral/metallurgical processes, especially flotation processes. Thus, this article will present a review primarily of point defects in relation to their effects upon flotation although other processes and defects will also be mentioned."

Jan 1, 1988

By Konstantina Chalastara

Mixed phase titanium dioxide (TiO2) nanoparticles synthesized through hydrolysis of TiCl4 solution at different conditions, namely concentration, pH, and residence time are characterized and evaluated as photocatalysts. The process is operated in a continuous stirred-tank reactor, CSTR giving blends of anatase, brookite, and rutile nanoparticles that were further evaluated to find the optimum mixture for a photocatalytic sorption material. The titania nanoparticles are first characterized in terms of photocatalytic activity under UV light illumination using an organic model compound (methyl orange) and after that are tested for removal of toxic selenate and selenite species from simulated effluent waters.

By H. Dijkman

The PAQUES Bio Systems&apos; core technology, marketed under the name THIOPAQ®, consists of various high-rate biological processes for metal-sulfur-water systems, complemented with common solid/liquid and gas separation steps. Sulfur species are converted to sulfide, which is a valuable component as it can be used for metals reduction and precipitation. Selective recovery of valuable metals can be employed, leading to revenue from metal values. In this paper, biotechnological systems for the treatment of metal sulfate solutions and dilute SO, gases are described. These installations can be designed to either produce predominantly aqueous (NaHS) or gaseous (H2S) sulfide. The emphasis here is on hydrogen sulfide gas. The main case history discussed is the demonstration plant that ran on hydrogen gas at Kennecott Utah Copper. Three years of operating experience clearly show that sulfate reduction with hydrogen gas is a viable option. Furthermore, the selective recovery of copper from leach water with the hydrogen sulfide produced was shown to be very effective.

Jan 1, 1999

By Takahiro Miki

In order to use metallurgical grade silicon (MG-Si) as a starting material for solar cell, phosphorus has to be removed from silicon because phosphorus is a n-type dopant. On the other hand, silicon, ferrosilicon, and silicomanganese are widely used as deoxidizers in steel refining processes. Since most of the phosphorus introduced during the deoxidation process is brought into final products, it is important -to lower the phosphorus content of these alloys. Hence, thermodynamics of phosphorus in such metals is important for the evaluation of dephosphorization processes. In the present study, thermodynamic properties of phosphorus in molten Si-P alloys at 1723- 1848K and those of Si-Fe-P and Si-Mn-P alloys at 1723K have been determined by equilibrating respective metals in a controlled phosphorus partial pressure. The results are expressed as follows.

Jan 1, 1998

By Yeliz Demiraya, Onuralp Yucelb

"Production of strontium metal from its oxide was studied under the pressure of 1-5 mbar by methalothermic process. SrO with 99 % purity was used in the experiments. Effects of Al powder addition (100, 200, 300 % of stoichiometric ratio) and time were investigated on recovering of metallic strontium. Effects of BaO addition (100 %, 200 %, 300 %) was also investigated. The final residues were examined for their chemical composition. XRD, AAS and Flame Photometer were used for chemical analysis. More than 96 % of strontium metal recovery can be obtained.IntroductionStrontium is an element which is used in many advanced technology applications. Barium strontium titanat, strontium bismuth titanat, and strontium bismuth tantalat thin films are promising materials in ferroelectric and Schottky-based microelectronics technologies, especially for memory applications. Physical vapor deposition (PVD) techniques as magnetron sputtering, thermal evaporation and molecular beam epitaxy (MBE) are the most widely used methods for growth of these thin films [1-3]. In these techniques high-purity of Sr metal is used as evaporation sources and sputtering targets. Furthermore, metallic strontium is used as a ""getter"" in electron tubes, and as an alloying elements in aluminum alloys [4].The most used Sr compound is SrCO3 and widespread process used in production of SrCO3 is the hydrometallurgical carbonation of celestite. Although there are considerable amount of Selestite reserves, SrCO3 and strontinum metal are not being produced in Turkey, yet [5].Concentrated celestite (SrSO4) is conversed to SrCO3 in carbonate media. Black ash and direct conversion processes are currently used methods. There are many satisfactory studies about hydrometallurgical carbonation of celestite and decomposition of SrCO3 [6, 7]. Since strontium metal is produced from it’s oxide (SrO), SrCO3 needs to be decomposed to SrO."

Jan 1, 2011

By Qinghai Pang

"With the increasing proportion of bituminous coal in blend coal, the safety of blend coal during pulverization and transportation is gradually being paid more and more attention. Therefore, the explosivity of bituminous pulverized coal (PC) with different volatile content from 25 to 38% was studied by measuring the combustion flame length after its injection into a glass pipe with the heat source installed in the center. The results indicated that high volatile content bituminous PC is apt to have higher explosivity. By blending different bituminous PC with 10% anthracite, the explosivity of bituminous PC showed a positive correlation with the proportion –OH radical. However, different bituminous PC seemed to have the same explosivity when the addition of anthracite increased to 20%. With the further increasing proportion of anthracite to 30%, the explosivity of bituminous PC with high –OH proportion became negligible while a weak explosivity of high –CH3 proportion bituminous PC still remained.IntroductionWith the increasing iron ore prices and decreasing steel prices, it has become critical for iron and steel enterprises to control the cost in ironmaking and steelmaking process. Blast furnaces (BF) are the main consumer in ironmaking process, which occupies 70% fuel consumption of total steelmaking process [1]. In this circumstance, any means necessary is taken by BF operators to lower the cost of iron in production. Coke and iron ore are the main expense in this process, who takes up a very high proportion in total cost. Pulverized coal injection (PCI) is the most efficient way to reduce coke ratio, which replace coke with relatively cheaper PC.At present, most of BF is injected with blend coal in the consideration of decent combustion property and quantity of heat. Simultaneously, bituminite and anthracite blending is an effective method to obtain blend coals with required composition and performance, such as volatile and ash content, etc. Nevertheless, a very huge gap was found between the price of bituminous coal and anthracite in some regions of China, in which the price of bituminite can be just 70% of the price of anthracite. Thus, iron enterprises in these regions attempt to possibly amplify the proportion of bituminite in blend coal. Increasing proportion of bituminite results in higher volatile content in blend coal, by which the safety of blend coal during pulverization or transportation was deteriorated.Relatively, coals with higher volatile content usually possess stronger explosivity, which means that volatile and explosivity may related to some extent. However, the relationship between volatile and explosivity is not of certainty for some PC with high volatile content around 40% was found to be inexplosive in comparison to the coals with lower volatile content. With the increasing proportion of bituminous coal in blend coal, investigations on the factors of PC explosivity have become more and more important. Therefore, bituminous coals with different volatile content were selected. The explosivity of blend coal and its relationship between volatile content and functionality was investigated in this research."

Jan 1, 2014

By Guy Deschênes

Thiourea solutions can be used as leach liquors to treat gold ores or slimes. It is also efficient to elute resins or strip solvents that were loaded in cyanides solutions. The hydrogen pressure reduction is a practical step to recover gold and silver from leach solutions, and strips and eluates without any destruction of thiourea. It is a critical point because these processes have to consider the recycling of the liquors to be irore economical. The effect of temperature, pressure, acidity, compotation of the solution and the nature of catalysts on pressure reduction by hydrogen were investigated. An electranetallurgical study was? carried out to investigate the mechanism. The composition of the products was studied by different analytical methods. The process shows a good selectivity to precipitate gold and silver in a thiourea solution containing iron and copper. Gold and silver concentrations can be decreased to 0.2 ppm and 0.1 ppm at respectively 70 KPa H2 and 28°C. No decomposition of thiourea was evident during the tests. Metals such as nickel powder or platinum activate the reaction and improve the reduction.

Jan 1, 1989

By Eric Klaffenbach

Valorization of slag from metallurgical industrial processes becomes ever more important as this may help optimizing and reducing the use of natural resources such as rock and sand. In view of this objective, metallurgical processes have to be analyzed in order to modify the slag composition so that it will meet the expected requirements of potential users of these resources. This paper gives the results of a thermodynamic analysis of the flash smelting process to understand the impact of operational parameters on slag chemistry and elemental partitioning in the process. It is shown that an increase of the matte grade and temperature leads to higher deportment of Pb, Zn and As to the slag. With increasing matte grade the volatilization of these elements decreases. Furthermore, the results indicate an increasing solubility of Cu and S in slag at higher temperatures.

By R. Craig McClung

Contrary to other sulfide minerals, where recovery is principally liberation controlled, the recovery of molybdenite is more complex. It is this complexity that initiated a geometallurgical investigation of molybdenites from Bingham Canyon. The aim of this investigation was to determine the effect mineralogy and/or mineralogical attributes have on recovery. All samples were analyzed using normal mineralogical techniques. The results reveal the presence of two distinctly different types of molybdenite. These have been identified as the two polytypes of molybdenite: i.e. hexagonal (2H); and rhombohedral (3R). The 2H-polytype occurs as textbook-shaped particles in quartz-molybdenite veins that are located in the current pit bottom. The 3R-polytype occurs as disseminated, “ball”-shaped particles with a dull or frosted appearance and are concentrated along the margins of the current pit. Concerning their metallurgical behavior, each type exhibits unique metallurgical properties that are consistent with those reported in the published literature. The 2H-polytype is easily ground and kinetically “faster” floating with surface attributes that are amenable to higher rates of recovery. This results in the production of a high quality concentrate under normal operating conditions. The 3R-polytype, by comparison, is difficult to grind and kinetically “slower” floating with surface attributes that are less amenable to recovery. Therefore, in deposits with higher concentrations of the 3R-polytype, modifications to the normal operating parameters may be necessary to improve recovery. This investigation highlights the necessity for understanding the mineralogical characteristics of any economic mineral(s), as these will have a direct impact on recovery.

By Zhang Hanbo, Niu Liping, Zhang Zhiqi, He Jicheng, Dou Zhihe

"Rutile, ilmenite and Al-Ca complex reducer were used to prepare high titanium ferrous alloy by enhanced reduction-SHS method. The effects of the complex reducer compositions and slag types on the enhanced reduction-SHS process were investigated. The high titanium ferrous alloys were characterized by XRD and SEM. The results indicate that the high titanium ferrous alloys consist mainly of TiFe2, AlTi3 and Al2O3. The oxide inclusions exist resulting in directly the high oxygen content and micro-structural defects in the alloys. The titanium and oxygen contents decrease, but the aluminum content in the alloy increases while the mass ratio of calcium in the Al-Ca complex reducers increases. When the mass ratio of Al/Ca in the Al-Ca complex reducer is 6:1, titanium, oxygen and aluminum contents are 63.75%, 3.01% and 10.72% respectively. When the mass ratio of Al/Ca is 5:1 titanium content is 55.00% nearly and aluminum content is higher than 14.00%, but oxygen content is lower than 2.0%.1. IntroductionThe high titanium ferroalloys with 65%~75% titanium have the advantages of low melting point and high titanium content. They are widely used in special steel refining, while they are also a kind of very important quality orientation alloys in the rage of aviation and aerospace. At present, the methods of preparing high titanium ferroalloy include vacuum remelting and thermit reduction. The alloys prepared by the vacuum remelting method have good qualities and low oxygen content, so it is widely used in Russia, Western Europe and other developed countries. In China, there are abundant rutile resources, but waste titanium is lack, therefore, the preparation method is the thermit reduction. But there are many quality defects in the high ferrotitanium alloy, including high oxygen content, unstable quality and so on. In order to improve the qualities of the high titanium ferroalloy, especially to reduce oxygen content, the domestic and overseas have done a lot of further researches. For example, Sichuan E-mei ferroalloy plant and Beijing Nonferrous Metal Research Institute have prepared high titanium ferrous with 73.77% titanium with natural rutile, but the oxygen content is high. Through controlling the quality of raw material, they obtained the better qualities, but the oxygen content is still very high. South Africa Mintek company have prepared high titanium ferrous alloy with low nitrate by plasma heating under the isolation air conditions, but they couldn’t also remove effectively oxygen in the alloy. The oxygen exists in the form of Al2O3 and titanium protoxide. So it can be speculated that except TiO2 not being fully reduced, the no-sufficient alloy-slag separation is the direct reason resulting in high oxygen and poor microstructure. In view of present technical difficulties during preparing high titanium ferroalloy by thermit reduction, this paper proposed a new method of preparing high titanium ferrous with low oxygen by enhanced reduction-SHS with Al-Ca complex reducer. Ca in Al-Ca complex reducer has stronger reductive ability, it can effectively strengthen the reductive degree of TiO2. The slagging agent CaO CaF2 and MgO can effectively reduce the viscosity of Al2O3 slag to improve its liquidities to strengthen alloy-slag separation effects so that to remove inclusions and oxygen. In this paper, effects of slagging agent type on the reduction and the qualities of high-titanium ferroalloy were studied."

Jan 1, 2012

By Fathi Habashi

The recovery of uranium from wet process phosphoric acid was applied on industrial scale in the 1940&apos;s by using octylpyrophosphoric acid as an extractant. Later, more efficient reagents were used, e.g., di(2-ethylhexyl) phosphoric acid and actylphenyl phosphoric acid. In the 1970&apos;s the rare earths in Kola phosphate were recovered in Finland and recently (1997) in Norway using HNO, as a leaching agent and di(2-ethylhexyl) phosphoric acid as solvent. It was demonstrated later on laboratory scale that both uranium and rare earths could be extracted from the rock by tributyl phosphate but at different pH values provided that the rock is leached with nitric or hydrochloric acids instead of the commonly used sulfuric. This new concept opens the way to the possibility of treating phosphate rock by in-situ, dump, or vat leaching for the recovery of phosphate values as well as uranium and the rare earths. Another solvent extraction process is used industrially for the purification of phosphoric acid using butyl and amyl alcohols.

Jan 1, 1998

By Derek J. Fray

Electric arc furnace dusts, especially those containing zinc ferrite, are notoriously difficult to process to give valuable products and non-toxic residues. The ideal process would remove and recover the toxic non-ferrous metals as pure metals, of commercial value, and non-toxic residue which can be used as a raw material in the steel industry. From an examination of the thermodynamics of the oxides and chlorides of the various elements in the dust, it is apparent that the chlorides of the toxic non-ferrous elements are more stable than the oxides while the reverse applies to the ferrous elements. This offers the opportunity for a complete separation of the zinc, lead and cadmium from the iron oxide. Results are presented for the chlorination of electric arc furnace dusts under oxidising conditions and the subsequent treatment of the chlorides to recover the pure metals and chlorine which can be recycled back to the reactor.

Jan 1, 1994

By Jorge Alberto Soares Tenório, Romano Espinosa, Felipe Fardin Grillo, José Roberto de Oliveira, Denise Crocce

"The aim of this work was evaluation of the recovery of Zn and Fe of the EAFD added to the hot metal in the form of briquette at temperature of 1500°C. The EAFD was agglomerated by cold briquetting and introduced in the hot metal. This study utilized a bench-scale equipment to melt, during this process to kept a flow rate of inert gas above the bath. Were collected periodically metal samples and the samples were analyzed for determination of the content of total silicon and carbon by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced and were volatized and collected by a cleaning system of dust (baghouse) located on top of the oven. More than 98% of iron were recovered from EAFD during the test. It was possible to produce a dust containing about 68% zinc by means of adding of EAFD.IntroductionIn the first semester of 2010, steel production was about 706 million tons, 27.9 % more than in the first half of 2009. Not a significantly increase if 2010 data is compared with the first semester of 2007 (only 7.2 % higher), before the world’s economic crises. Steel production is divided into two main routes. The first one, and most used, is the Basic Oxygen Furnace Process (BOF process), which in 2008 accounted for approximately 67.1 % of steel production. The second route is carried out in the Electric Arc Furnace (EAF) that in 2008 represented 30.6 % [1 ].Electric arc furnace dust (EAFD) is a solid waste generated during the steel making process. It is classi?ed according to NBR 10004 as dangerous solid waste-class I, because the elements Pb e Cd leach in water exceeding the maximum limits permitted by the NBR 10004 [2 ]."

Jan 1, 2012

By Carla Lupi

NiMH sealed cells (portable cells) are today widely used in all consumer applications replacing primary alkaline batteries: wireless mobile communication, portable computers and camcorders, are the largest application segments. The Italian market. of NiMH cells is steadily growing, following the impressive penetration rate of the cellular phones. The organization of a national collecting system and correct recycling process are the key factors to prevent environmental impact associated to these wastes, while the metal values recovery can improve the feasibility of the recycling process The University of Rome, Texeco Engineering S.d, and MO.SMO.DE. S.a.s. have developed a combination of mechanical and hydrometallurgical processing to recover Nickel, and Cobalt salable products and rare earths intermediate products. A new plant located in South Italy, designed after this technology, is able to recycle waste Ni-MH batteries collected in the Italian territory, together with other industrial and portable batteries based on different chemistries. The process is able to treat both individual cells and plastic power packs and includes as basic steps an original crushing and elutriation treatment to separate plastic, metallics, and active mass components that are subsequently treated by a hydrometallurgical process to recover Ni, Co, and RE. The hydro metallurgical main steps are: acidic leaching, RE separation, multistage precipitation of Ni, Co and Fe and final solvent extraction on dissolved Ni and Co salts. For each operation the operative condition have been determined.

Jan 1, 2000