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By Naixiang Feng, Shaohu Tao, Zhihui Wang, Yuezhong Di

"A novel vacuum aluminothermic reduction lithium process was developed in present work which used lithium carbonate, alumina and calcium oxide as raw material. The process mainly contained three steps. The first step is that LiA102 clinker is prepared in ambient environment, then metal lithium is vacuum extracted from LiAl02 clinker with aluminum power as reducing agent, and the last step is that alumina is leached from the reduction residue with a mixture of sodium hydroxide and sodium carbonate. The results show that the lithium reduction ratio can be over 95% under the conditions of reduction temperature 1423K, reduction time 3h, and aluminum excess 20%. The main components of reduction residue are CaO· Al203 and 12Ca0·7Alz03. The alumina leaching rate of calcium aluminate in residue is over 80%. High-whiteness aluminum hydroxide can be obtained by carbonation precipitation of the reduction slag leaching solution.IntroductionWith a density about half of water, lithium is with the lowest density of all solids, mere 0.5 g/cm3 at 20 °C [l]. Lithium is widely used in aerospace, aviation, nuclear-generated power and electric battery industry. Nowadays, over 90 % of the world's primary lithium is produced by molten salt electrolysis [2-4]. But the development of molten salt electrolysis will be effected by some factors: cost, environment, and so on. Vacuum thermal reduction may be used extensively in future because of its low-energy consumption, high-purity and short-cycle."

Jan 1, 2013

By Michael Altepeter

Big River Zinc Corporation, located in Sauget, Illinois, operates a neutral leach residue circuit. The residue produced in the circuit is sold to lead smelters for subsequent recovery of valuable metals. A research program was initiated several years ago to find a means of treating the residue at Big River Zinc to recover the valuable metals. The Ausmelt submerged lance reactor was selected as the best alternative for the first step of the process. Pilot scale tests were conducted at Ausmelt's facilities in Melbourne, Australia. Separations were excellent. 99%+ of the Zn, Pb, Cd, and Ag contained in the residue reported to the oxide fume. 99%+ of the SiO2,, Fe, Mg, and Ca in the residue reported to the slag which passed the EPA TCLP test. Subsequent leaching of the oxide fumes and purification of the leach solutions using conventional procedures produced solUtions suitable for zinc electrowinning and an upgraded lead sulfate cake for sale.

Jan 1, 1992

By Ann M. Hagni

Microscopic and sub-microscopic gold commonly occurs in the sulfides pyrite (FeS2) and arsenopyrite (FeAsS). To recover refractory gold from pyrite and arsenopyrite, these sulfides are roasted to create porosity and permeability prior to cyanide leaching. A new technique of adding Ca(OH)2 and roasting, lime roasting, is being tested fro retention of contaminant sulfur and arsenic and effectiveness of gold extraction. The lime roasting of pyrite at 500°C contains anhydrite (CaS04), oldhamite (CaS), calcium sulfite (CaS03), hematite (FenOs), magnetite (Fe304), and minor amoupts of pyrrhotite (Fel.,S) and pyrite. At 600°C, 650°C and 700°C the main constituents are anhydrite, oldhamite, and hematite. At 750°C, 800°C, and 850°C anhydrite and hematite are the predominant phases with minor oldhamite. The roasted arsenopyrite at 450°C contains arsenic sulfides, calcium sulfite, hematite, and minor oldhamite, magnetite, and pyrrhotite. At 650°C 700°C 750°C and 800°C, anhydrite, oldhamite, arsenic sulfides, and hematite are present. At 850°C, the same minerals are present with only minor oldhamite. The textures indicate excellent porosity and permeability at high temperatures. At lower temperatures, rims of low porosity and permeability surround many of the pyrite and arsenopyrite particles, and the complete oxidation process from pyrite to pyrrhotite to magnetite to hematite can be observed in individual particles. Additional process mineralogy techniques employed in this study are electron spectroscopy for chemical analysis (ESCA) and cathodoluminescence microscopy (CLM) in the determination of the calcium-sulfur- oxygen phases. Automated scanning electron microscopy-energy dispersive spectroscopy was utilized to analyze particles for gold content. Reflected light microscopy (RLM) revealed arsenopyrite and pyrite encapsulated in quartz particles of the gold-bearing concentrate, gold roast calcine, and cyanide leach residue.

Jan 1, 1993

By Takao Yasugi

The majority of copper in the raw material migrates to the de-copperized dross that forms when the crude lead produced in the blast furnace is treated in the de-copperizing process. The de-copperized dross is treated in the electric furnace producing matte, speiss, and crude lead. The de-copperized dross also contains the silver. Therefore, it is important to improve the rate of silver migration to the crude lead. For this reason, the behavior of silver between the matte, speiss and crude lead phases was examined. At the same time, several tests to improve the percentage of silver migrating to crude lead were conducted.

Jan 1, 2003

By Raj P. Singh

Applications of cementation in the recovery of metal ions from process solutions have been known for a long time. Cementation reactions involve electrochemical precipitation of a noble metal from solutions of its salts on a more electropositive metal which, in tum, progressively dissolves. For example, addition of zinc metal powder in a solution containing zinc and cobalt ions would allow for the precipitation (separation) of cobalt according to the following chemical reaction. This paper pertains to the recovery of cobalt from cobalt process solutions via a cementation reaction on aluminum shavings (metal scraps from cans etc). Specifically, we report on the characterization of cobalt process solutions, a by-product obtained from cobalt chemicals, and the kinetics of cobalt, nickel and manganese cementation from process solutions on aluminum shavings.

Jan 1, 2000

By Fathi Habashi

Nitric Acid has been used for over 50 years in the uranium industry and in phosphate fertilizer manufacture. Its application in the treatment of sulfide concentrates is relatively recent. A review of recent developments is given.

Jan 1, 1999

By Lawrence L. Brown

As part of the Federal effort to help maintain an adequate supply of fertilizer materials, the Bureau of Mines conducted research to characterize complex low-grade Michigan phosphate materials and to devise methods for recovering fertilizer-grade phosphate concentrates. The rock is from middle Precambrian sedimentary formations in the Marquette Range located in the central part of the Upper Peninsula of Michigan. Occurrence of phosphate-bearing sediments in Precambrian rocks is rare. This deposit, containing 12 to 15 pct P2O5 is believed to be the richest Precambrian phosphate deposit in the United States. Petrographic examination showed that the conglomeritic rock contains crystalline apatite both in "black pebbles" and in quartz matrix. Attrition scrubbing and sizing tests showed that there is no tendency for phosphate to concentrate in any of the sized fractions. In beneficiation tests, which included grinding to minus 325 mesh followed by phosphate mineral flotation using a fatty acid-fuel oil collector, a phosphate concentrate was obtained that had a grade of 30 pet P2O5 and a P2O5 recovery of 72 pct. This concentrate should be suitable for fertilizer manufacture.

Jan 1, 1982

By K. Walanabe

Kosaka Smelter & Refinery has a history of more than a century as a metallurgical department belonging to Kosaka mine. It has treated for a long time the "Black Ore" or the complicated concentrates dressed from it. The "Black Ore" is composed of black sulfides. It contains not only valuable metals such as gold, silver, copper, lead and zinc but also some impurities like arsenic, antimony and bismuth. With the development of Kosaka's floatation technology, five kinds of concentrates (copper, zinc, lead, pyrite and barite) have been separated from the "Black Ore" but the separation was not complete and each concentrate contained some unfavorable impurities. In 1980s the highly appreciated yen and the drop of the metals prices forced many domestic mines to close their operations. Since then Kosaka Smelter has changed its way of operation to a custom smelter. Now more than 95% of copper concentrates are imported to take advantage of this technology of "Black Ore" treatment. It mainly treats the raw materials that contain high gold and silver like the "Black Ore". Recently, Kosaka has been working on the recycling of the metals from the printed circuit board scraps and sludge which contain some precious metals. The volume of the recycled metal is continuously increasing.

Jan 1, 2003

By Jewel Gomes

Produced water (PW) is salty water trapped in the reservoir rock and brought up along with oil or gas during production. It subsists under high pressures and temperatures, and usually contains hydrocarbons and metals. Therefore, it must be treated before being discharged to surface water. Different techniques are being used to treat PW through phase separations, system control and design, and chemical treatments. In this paper, we discuss our experimental results on treating PW through electrocoagulation (EC). The performance of EC was investigated for the reduction of chemical oxygen demand (COD) and metal ions. Effects of different electrodes, residence time, current density, and pH were also studied to optimize the treatment conditions. Different kinds of cleansing agents, such as lime and borax were used to break the buffering effect encountered during treatment. FTIR, SEM/EDS, and XRD were used to characterize the EC-floc and thus to elucidate removal mechanisms.

Jan 1, 2009

By A. Kar

A mathematical model is presented for pure titaqium deposition from titanium tetrabromide on a stainless-steel (SS 304) substrate. Five three-dimensional, transient, and nonlinear partial differential equations are used to account for the diffusion of various species inside the deposition chamber and the thermal decomposition of titanium tetrabromide, titanium dibromide, and titanium monobromide at the surface of the substrate in order to determine the thickness of the titanium film deposited on the substrate. The effects of various process parameters on the deposition and shape of titanium films are examined, and under certain conditions, the deposited titanium films are found to have volcanic profiles.

Jan 1, 1992

By C. Cheung, U. Erb

"Over the past few years, nano-processing of magnetic materials has received considerable attention, because many magnetic and other application-specific properties have been shown to be enhanced in materials with ultrafine grain size. This paper reviews recent advances in the production of nano-processed soft magnetic materials such as pure nickel and cobalt as well as binary nickel-iron and ternary nickel-iron-chromium alloys by electrodeposition. Magnetic, electrical and mechanical properties of these materials are presented and discussed in terms of their microstructural defects.IntroductionIn recent years, nano-processing of materials to enhance their magnetic properties has received considerable attention [1-23]. Thin films, compositionally modulated thin films, granular films and bulk materials have been produced by many different techniques. These include gascondensation [1-6], ball-milling [7,8], chemical processing [9,10], metal-organo complex routes, solution reduction and co-precipitation [11], sol-gel methods [12], sputtering [12-14], rapid solidification [15], devitrification of amorphous alloys [16-19] and electrodeposition [12,20,21]. The potential application of nano-engineered materials with enhanced magnetic properties has been specifically discussed for soft magnets [18,19,22,23], hard permanent magnets [15] as well as for layered materials showing giant magnetoresistance effects [13,14] and nano-composites for magnetic refrigeration [11,12].The purpose of the present paper is to review recent advances in the development of nanocrystalline soft magnetic materials by electrodeposition methods. These materials could find applications in areas such as magnetic recording heads, high efficiency electric motors, transformer cores, etc."

Jan 1, 1994

By Mike Trovant, Stavros A. Argyropoulos

"A fixed grid numerical model for phase change problems is proposed. The model solves for heat transfer and fluid flow, via the coupled solution of the energy, continuity and momentum equations. In addition, the numerical scheme accounts for temperature varying thermophysical properties and determines the shrinkage profile resulting from phase and density change. Simulations are run to determine the effect of varying model parameters and wall cooling rates on the location and shape of the shrinkage void formation in cylindrical casts. Results are shown for both aluminum and magnesium.IntroductionThe mathematical modeling of phase change processes (be they solidification or melting problems) entails solving for many interrelated phenomena. A comprehensive numerical simulation of the casting of a metal, for example, would have to account for: (a) heat transfer in both the solid and liquid portions of the metal and in the mold, (b) the release of latent heat during phase change, (c) fluid flow behavior in the liquid portion of the metal, (d) temperature induced shrinkage caused by liquid contraction and solidification contraction, and (e) the development of thermal stresses with accompanying shrinkage in the solid portion of the cast and mold. A schematic of the relationships that exist between the coupled equations which govern solidification is shown in Figure 1."

Jan 1, 1994

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 XUEWEN WANG, Bowen Li, Mingyu Wang

A novel technology characterized by higher extraction of vanadium and recovery of valuable elements was developed to recover vanadium from stone coal. The brief flow of the novel technology mainly includes low temperature sulphation roasting, water leaching, recovering potassium, aluminum, copper and selenium, solvent extraction enrichment vanadium, precipitation of red vanadium, removal sodium from red vanadium and calcinations. The total recovery of vanadium reached 76.3%, which was higher than the current applied technology. The novel technology was environmentally-friendly and could extract vanadium from the stone coal, in which the content of V2O5 was less than 0.8%.

Jan 1, 2015

By N. Kanari

The thermal decomposition studies of two zinc basic carbonate samples were carried out up to 400 "C by thermogravimetric analysis, boat experiments and differential scanning calorimetry measurements 'DSC'. The initial samples and the solid decomposition products were analyzed by scanning electron microscopy, x-ray diffraction and laser particle size analyzer. The thermal decomposition of both samples started at about 150 "C and the rate of decomposition became significant at temperatures higher than 200 "C. The apparent activation energies 'Ea' in the temperature range 150-240 "C for sample decomposition were between 132 and 153 kJ1mole depending on the sample origin. The XRD analyses of the intermediately decomposed samples and the DSC results up to 400 "C suggest that the decomposition reaction probably occur in a single step.

Jan 1, 2002

By Y. Yang, S. Peelman, J. Sietsma, Z. H. I. Sun

The rare earth elements (REEs) present in the Kiruna iron ore mine tailings are being considered as a new REE resource for the EU. These tailings, after beneficiation, contain approximately 5000 ppm of rare earths, concentrated in apatite and monazite minerals. To economically extract the REEs from these tailings the phosphorous contained within the apatite must also be extracted and the waste production of the process should be minimal. To achieve the extraction of REEs and phosphorous HCl and HNO3 were investigated as possible leaching agents. Based on the results a leaching process using HNO3 is proposed. This process produces H3PO4 from the apatite while simultaneously dissolving the REEs. The resulting leach liquor is then cooled to remove the unwanted Ca as Ca(NO3)2. Analysis of the leach liquor reveals extraction ratios of between 75% and 100% for the heavy REE (e.g. Y, Eu, Dy, …) and below 40% from the light REEs (i.e. Ce, La). Full phosphorous extraction was also achieved.

Jan 1, 2016

By Sabine Knott

The thermodynamic properties of four liquid ternary zinc alloys, Au-Sn-Zn, Ag-Sn-Zn, AI-Sn- Zn and Cu-In-Zn were measured with an electromotive force (emf) method at three or four cross-sections with an constant X:Sn or Cu-In ratio. At the Au-Sn-Zn and AI-Sn-Zn system calorimetric measurements were also carried out in order to compare the integral enthalpy of mixing from the direct measurements with the data of the emf measurements, which were derived by Gibbs-Duhem integration.

Jan 1, 2003

By Mikiya Tanaka

This paper outlines our attempt to establish a recycle process of nickel in the spent baths and waste rinse water of electroless nickel plating plants using solvent extraction and solvent-impregnated support, Solvent extraction studies of nickel from actual spent baths revealed that (i) nickel is efficiently extracted by a hydroxyoxime extractant such as LIX84I at a pH greater than 6 and is readily stripped with sulfuric acid, and (ii) the mixtures of LIX63 and acidic organophosphorus extractants (D2ERP A, PC88A, and Cyanex 272) enhanee the nickel extraction efficiency to a sufficient degree without pH adjustment, but at the same time, reduce the stripping efficiency. The application of acidic organophosphorus extractants to selectively remove impurity metal ions (iron and zinc) from a real spent bath before extracting nickel lead to the finding that PC88A and Cyanex 272 effectively remove iron and zinc without pH adjustment leaving nickel in the raffinate. The removal of nickel from the waste rinse water was also studied. Solvent-impregnated supports with a macroporous resin and oil sorbents made of natural kapok fiber and synthetic fiber as supports were applied using D2EHPA and LIX860 as the extractants. During the batch operation, nickel is removed with a high efficiency without pH adjustment. During the column operation, however, the effective removal is hindered by (i) the dissolution of the nickel-D2EHPA complex into the aqueous phase in the high loading region, and (ii) the slow removal rate of the LIX860-impregnated support.

Jan 1, 2003

By J. V. Atwood

The U.S. Bureau of Mines has developed a novel Double Membrane Electrolytic Cell (DMEC) that exhibits unique features for recycling contaminated metals and metal alloys. The DMEC incorporates two anionic ion exchange membranes, separating anodic and cathodic regions of the cell. The ion exchange membranes prevent significant transport of unwanted cationic impurities to the catholyte from the impure anolyte while the anion/cation balance in cell compartments is maintained through the free movement of anions between compartments. The membrane barrier makes it possible to electro refine highly contaminated materials or to electrowin from solution while utilizing alternate anode reactions. Sinceanolyte and catholyte cross contamination has been eliminated, premium cathode products are produced. The DMEC has been tested at bench, pilot, and commercial scales. Configuration of the DMEC, cell operation, scale, up efforts, and significant design factors are discussed. Two separate recycling investigations utilizing DMEC technology are presented. The first investigation examines recovery of high purity cobalt and nickel from severely contaminated super aIloy scrap. The second involves? upgrading contaminated cobalt in the U.S. Government's National Defense Stockpile. Capital and operating costs for both potential applications are presented.

Jan 1, 1995

By Guiqing Zhang, Liansheng Xiao, Zuoying Cao, Li Zeng

A new process of direct solvent extraction of nickel from sulfuric acid leach solutions of low grade and complicated nickel resources using a novel extractant HBL110 was proposed. The basic performance of new organic system was investigated and the continuous pilot plant and the industrial test were conducted. The results indicated that the extractant of HBL110 can be used to directly extract nickel selectively over iron, aluminum, manganese, magnesium, calcium and chromium from sulfuric acid leach solutions. The loaded organic solution can be easily stripped using dilute H2SO4 solutions. Both kinetics of extraction and stripping of nickel were fast. The continuous pilot plant test with the sulfuric acid leach solution of laterite containing 6.22g/L Ni2+, 14.1g/L Fe3+, 0.73g/L Fe2+, 33.9g/L Mg2+, 1.58g/L Al3+, 0.495g/L Ca2+, 0.97g/L Mn2+ and 0.5g/L Cr3+ as feed in mixer-settlers showed that the process had run stably with 98% recovery of nickel. The concentration of nickel in strip liquors reached as high as 50 g/L while the removals of Fe3+, Fe2+, Mg2+, Al3+, Ca2+, Mn2+ and Cr3+ were 98.5%, 91.5%, 99.95%, 99.8%, 99.1%, 98.6% and 99.5%, respectively. The industrial test with the sulfuric acid leach solution of electroplating sludge containing 11.5g/L Ni2+, 2.68g/L Fe3+, 7.54g/L Cr3+, 0.61g/L Mg2+, 2.09g/L Al3+, 0.68g/L Ca2+, 0.022g/L Mn2+ and 0.154g/L SiO2 as feed in mixer-settlers also showed that the process had operated successfully with 99.5% recovery of nickel. The concentration of nickel in strip liquors reached 42.7 g/L while the removals of Fe3+, Cr3+, Mg2+, Al3+, Ca2+, Mn2+ and SiO2 were 99.2%, 99.77%, 99.73%, 99.56%, 99.57%, 98.51% and 98.75%, respectively. The new process exhibited big advantages of short flow sheet, high recovery of nickel, high removal of impurities, low chemical reagent consumption and low cost. Application of this process in industry is expected to make important impact on the extraction of nickel from sulfuric acid leach solutions and to deliver good environmental and economical benefits.

Jan 1, 2016