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By R. Cameron

The growing use and acceptance of electric vehicles (EV), as evidenced by the record sales of over 750 thousand vehicles in 2016 and a current global EV stock of 2 million vehicles, is putting pressure on sourcing raw materials such as cobalt, and to a lesser extent, nickel. Global supply is poorly diversified, with 50– 60% of global cobalt production sourced solely from the Democratic Republic of Congo (DRC). One potential source for cobalt and nickel are low-grade nickeliferous pyrrhotite tailings, of which 50–100 million tonnes are present in the Sudbury area alone. This paper presents the extraction of cobalt and nickel from this material using a combination of flotation and bioleaching technologies. The findings of a high-level techno-economic analysis of the proposed processing flowsheet are presented.

By M. J. Collins

Pressure leaching of zinc sulphide concentrates has been practiced commercially for nearly two decades. The process, which includes direct leaching of concentrate with spent electrolyte in an autoclave, has been commercialized at four separate locations to date. In pilot studies carried out in the Dynatec lab in Fort Saskatchewan, dozens of additional zinc concentrates have been shown to be amenable to pressure leaching. This paper highlights recent improvements in zinc pressure leaching that have been identified through process development studies, and how the experience gained in these studies has been utilized in the development of a new copper pressure leach process.

Jan 1, 2000

By Fernanda de Paula, Lázaro A. Rohen, Sérgio N. Monteiro, Rafael G. de Castro, Carlos Maurício. F. V, Maycon A. Gomes, Frederico M. Margem, Anna C. C. Neves

Synthetic fiber has been gradually replaced by natural fiber, such as lignocellulosic fiber. In comparison with synthetic fiber, natural fiber has shown economic and environmental advantages. The natural fiber presents interfacial characteristics with polymeric matrices that favor a high impact energy absorption by the composite structure. However, until now little has been evaluated about the hemp fiber incorporated in polymeric matrices. This study has the purpose of evaluate the impact resistance of this kind of epoxy matrix composite reinforced with different percentages of hemp fibers. The impact resistance has substantially increased the relative amount of hemp fiber incorporated as reinforcement in the composite. This performance was associated with the difficulty of rupture imposed by the fibers resulting from the interaction of hemp fiber / epoxy matrix that helps absorb the impact energy.

Jan 1, 2015

By William Petruk

The behaviour of sphalerite during mineral beneficiation of base metal ores has been studied at CANMET and other institutes for at least 15 years by determining the liberations of sphalerite in mill products and calculating the recoveries of liberated and unliberated sphalerite in zinc concentrates. Sphalerite in base metal ores commonly occurs as layers and as interstitial material between pyrite. Layered sphalerite is generally liberated during primary grinding, but interstitial sphalerite requires re-grinding to achieve liberation. Around 95% of liberated sphalerite is generally recovered in zinc concentrates frau zinc circuit feeds. A series of tests was conducted on sphalerite in the ore of Brunswick Mining and smelting during a continuous fine tuning operation of the concentrator. It was found that a grind of 80% minus 37 micrometres was required to liberate the interstitial sphalerite. The fine grind increased Zn recoveries from 75% to 78-80%, but produced liberated slimed sphalerite which was lost. Since regrinding to a fine grain size is needed to obtain the desired sphalerite liberation, a method of recovering the slimed sphalerite is required.

Jan 1, 1990

By Xiao Songwen

Based on the anion coordination polyhedron growth unit theory, the polymorph transformation mechanism of antimony white (Sb2O3) in hydro-process was investigated. The new findings had been verified in the commercial-scale test and it was shown that adding a small amount of tartrate ions was economical and effective for polymorph transformation of antimony white in hydro-process.

Jan 1, 2003

By Djalma Souza, Rubén Sánchez, Regina Maria Pinheiro, Carlos Maurício Fontes Vieira, Sergio Neves Monteiro

"This work has for objectives to characterize a waste generated in the form of sludge during the treatment of the effluent of a paper making industry and to evaluate the effect of its incorporation up to 10 wt.% on the properties of a clayey body used for brick production. For the characterization of the waste the following techniques were used: X-ray diffraction, X-ray fluorescence, differential thermal analysis and termogravimetric analysis with mass spectrometry. Specimens were prepared by uniaxial pressing at 20 MPa before firing at 750 °C. The physical and mechanical properties evaluated were: linear shrinkage, water absorption and flexural rupture strength. The results showed that, in agreement with the characteristics of the waste, its recycling into red ceramic can contribute to decrease the consumption of fuel during the firing stage. However, the waste changes the physical and mechanical properties, generating a deleterious effect on the water absorption and flexural rupture strength of the ceramic.IntroductionAccording to the Brazilian Association of Pulp and Paper, in the last 10 years, the global production of paper grew 35%. Brazil produced 8,2 million tons of paper in 2004 and held the position of the seventh largest world manufacturer of pulp, with about 9,4 million tons per year [1]. The pulp and paper industry generates effluents that present problems related to their disposal, even after the treatment. Among the solid wastes generated by this industry, the main waste is the primary sludge from the effluent treatment plant (ETP).After the initial treatment the decanted solids go through a dewatering stage, generating the solid form denominated primary sludge. This sludge resembles a paper paste of dark gray color when humid, and clear gray color when dry. This primary waste is composed basically of kaolin, pulp, traces of chemical substances and water. This waste generated in the pulp and paper industry depends on the characteristics of the process and of the employed techniques. It can vary significantly from one industrial unit to another, even in the case that the final products are similar. Its composition is approximately 60% of kaolin and 40% of pulp, and these percentages can vary in some moments as a function of the process [2,3]."

Jan 1, 2008

By I. C. Knight

The current levels of copper smelter by-product acid production are reviewed on a regional basis, together with the possible changes in the future. There will be increasing pressure for all smelters to achieve a sulphur capture level of at least 95% by the end of the decade.

Jan 1, 1996

By Pragna N. H. Bhakta

The minerals industry is under political and economic pressure to reduce its processing wastes and minimize their impact on the environment: Recycling is one of the means by which the minerals Industry can reduce the quantities of effluents and residues that are discharged to the environment. The wise use of available resources is not only an environmental necessity but also an economic benefit as natural mineral resources are depleted and/or become more complex. The purpose of this paper is to review the technical and regulatory issues that will help shape the future of minerals recycling over the next ten years. Research and development to address technical issues will be discussed with emphasis on the Bureau of Mines recycling research program.

Jan 1, 1992

By S. V. Ketov, V. P. Menushenkov, V. S. Shubakov

"The glass samples were obtained by melting of the oxides mixture SrO-Fe2O3-B2O3(Al2O3) at 1200-1250°C with subsequent quenching of the melt on quickly rotating steel roller. Submicronsized Sr(Fe,Al)12O19 particles were formed in glass-ceramic matrix during the crystallization aging of glass. The aging temperature Tag varied in the range 650-950°C. The submicron-sized hexaferrite powder was obtained by removing of the matrix phases using etching. The samples were characterized by X-ray diffraction, scamiing electron microscopy and magnetization measurements. The glass-ceramic material exhibits very high coercivity value up to 10 kOe. The samples of magnets were obtained by pressing of the hexaferrite powder at RT and subsequent aging in the range 900-1200°C. The aged samples exhibit coercivity value up to 8 kOe.IntroductionStrontium M-type hexaferrites have been widely used in technology and industry mainly for production of permanent magnets owing to their appropriate magnetic properties, chemical stability and low cost [1,2]. The SrFe12019-based compounds are characterized by high magnetocrystalline anisotropy and single easy magnetization axis. The highest coercivity is received for monodomain, defect-free single crystal particles with size D - 100 mn. Finely grained strontium hexaferrite prepared by chemical methods such as sol-gel pyrolysis and oxide glass crystallization exhibits high coercivity up to 6-8 kOe [3-5]. Owing to the partial substitution of Al for Fe in the strontium hexaferrite leading to the increase in the magnetic anisotropy field Ha=2Ki/M,, the increase in the coercivity may be received [6]. The notable results were achieved using the SrO-Fe2O3-AlzO3-B2O3 glass crystallization and formation of perfect submicron crystals of alumina-doped hexaferrite [ 6, 7]. The coercive force of glassceramics reached values of up to 10 kOe. Hexaferrite particles are well faceted and have the shape ofhexagonal bipyramids with truncated vertexes [7].In the present paper, we report results of our investigation into the SrO-Fe2O3-B2O3(Al2O3) glass crystallization, hexaferrite powders and permanent magnets, which were prepared by pressing submicron-sized hexaferrite powders at RT and subsequent sintering at 900-1200°C."

Jan 1, 2012

By B. J. Scheiner

The presence of organic materials in gold ores interferes with gold extraction by cyanidation. The carbon contained in the ore has been shown to adsorb gold cyanide complex from solution. Removal of the carbon content by roasting or chemical oxidation prior to cyanidation results in gold extractions of 85 to 95%. This paper discusses how the mineralogy of the carbonaceous gold ores affects gold recovery by cyanidation. It also discusses the advantages and disadvantages of roasting and chemical treatment to render the ore amenable to cyanidation.

Jan 1, 1987

By William A. Apel

Several different strains of bacteria have been shown capable of reducing hexavalent chromium, Cr(VI), to Cr(III), a less toxic, .. more readily recoverable form of Cr. This paper examined the Cr(VI) reduction efficacies of 3 different Cr(VI) reducing bacteria: Pseudomonas f1uorescens LB300., Pseudomonas aeruginosa PAOI, and Pseudomonas aeruginosa PAOI (pCROI) It was demonstrated that all three bacterial stratns reduced Cr(VI) primarily during their exponential growth phases while using glucose as their carbon and energy source. Significant differences in the three organisms' Cr(Vl) reduction capabilities depending on initial Cr(VI) concentrations were also demonstrated. P. aeruginosa PAOI showed superior Cr(VI) reducing capabilities over the. entire range of Cr(VI) concentrations tested while the Cr(VI) reduction capabilities of the other two strains were increasingly inhibited as Cr(VI) concentrations increased.

Jan 1, 1991

By Carla Lupi, Alessandro Pescetelli

"Spent lead battery recycling still shows few weak points in the achievement of a 100% recycling of different waste matters and by- products arising from the recycling process. Some of said problems are dealing with aqueous streams outgoing the recycling plant, and more particularly, a) the waste waters discarded from the breaking and separation unit, b) purification of the spent electrolyte drained from waste batteries and upgrade to a quality compatible with full re-use by the batteries’ manufacturers, c) purification of the mother liquors discarded in the sodium sulfate crystallization process so to produce a salt of commercial grade. All of the above listed problems have been satisfactorily overcome applying an electrochemical process that, through different process conditions and parameters, is able to remove the harmful impurities that hinder the successful commercialization of such by products, or, at least, that can avoid heavy and expensive treatment plant and operation.IntroductionAlmost 100% of commercial lead and lead alloys produced by secondary lead plants is recycled to the new lead accumulators manufacture. The other by-products and residues produced through the lead recycling process may be classified into two groups:a) matters reusable in the new accumulators production processb) matters produced as a result of various reagents and additives used in the recycling process, to be sold to different market sectorsQuality and saleability of by-products are significant points for the economics of the secondary lead plant operation, because, if said by-products are not saleable, they are just wastes, so offsetting potential revenues, and, at the same time, adding a heavy burden to operating cost, like disposal cost [1]. When looking at a typical, modern lead scrap batteries recovery cycle, it is quite evident that we are still rather far from dealing with a waste-less technology (fig.1).The group a) includes 3 by-products produced through the breaking process: among those matters the polypropylene only usually reaches a standard quality suitable for sale to lead manufacturing sector or to other sectors as well. The other two by-products, electrolyte and separators, do not still reach, through a viable and effective regeneration process, a quality standard sufficient for their re-use in the lead batteries sector ."

Jan 1, 2008

By M. M. Coleman

An investigation of the behaviour of sphalerite, chalcopyrite, galena and pyrite during flotation was conducted on selected circuits in the Brunswick Mining and Smelting Corporation Ltd. concentrator in Bathurst, NB. Samples were collected from 59 locations and analyzed for Zn, Pb, Cu, Ag, Fe, As, Sb, Sn, Bi and S. Metal balances were computed using the CAMP Material Balance Program (MATBAL 5) and the metal recoveries for each cell and circuit were calculated. An automated image analyzer interfaced with an electron microprobe was programmed to measure the size of sphalerite, chalcopyrite, galena and pyrite grains in each sample. The percentage of each mineral occurring as free grains and the relative amount of each mineral present in binary and ternary particles was calculated. The recoveries and losses of Pb, Zn and Cu are compared with the amount of liberated and unliberated galena, sphalerite and chalcopyrite present in the concentrates and tailings.

Jan 1, 1989

By C. A. Morais

The present work describes the development of an efficient and relatively simple process to obtain high grade CeO2 from a mixed rare earth chloride solution. The process involves cerium oxidation and precipitation by addition of a KMnO4-NaCO3 solution. The experiments were carried out at room temperature (25 1° C). The results indicated that the major parameters affecting cerium recovery are the molar ratio of KMnO4/Ce, the initial acidity of the chloride feed solution and final pH of Ce(OH)4 precipitation. In strong acid solutions (pH < 1), the oxidation of Cl to Clo took place in addition to the oxidation of Ce(III) to Ce(IV), so increasing the permanganate consumption. Conversely, low acidity (pH >3) led to coprecipitation of the other rare earth elements. Under the selected conditions, cerium was selectively precipitated as ceric hydroxide, together with some manganese dioxide. Further purification was carried out by the dissolution of Ce(OH)4 in HCl, followed by precipitation as cerium carbonate. The filtrate was neutralised with a Na2CO3 solution in order to recover the associated rare earth elements for further separation. The final product, assaying 99.7 % CeO2, was obtained with a recovery of nearly 100%.

Jan 1, 2003

By Thenepalli Thriveni, Ch. Ramakrishna, Yujin Jegal, Ji Whan Ahn, Jyothi Rajesh Kumar

In alumina production or alumina refining, bauxite is converted to alumina (aluminium oxide) The rare-earth elements (REEs) are a group of 17 chemically similar metallic elements (15 lanthanides, including scandium and yttrium). Rare earth elements play a key role in many industrial applications, petroleum refining, clean energy, automobile, electronics, and defense applications. These rare earths are essential to the success of green technologies. China today controls more than 95 percent of the rare-earth supplies and nearly all rare-earth refining and after 2009 year rare earths crisis raises due to China’s export restrictions and growing internal demand for rare earth elements. The extraction of gallium and yttrium from Korean red mud (KC red mud) by selective acid leaching was explored. The recovery of gallium and yttrium from a leach solution of the Korean red mud using solvent extraction was studied. A number of extractants were investigated for the extraction of those mentioned two rare earth elements and also we proposed a flow sheet of rare earth elements respectively. The toxic heavy metals presented in KC red mud were removed by CO2 stabilization.

Jan 1, 2015

By O. Forsén

In the first part of this paper is studied the behaviour of small amounts of impurity elements? in the solidification of copper anodes. In the second part the dissolution of these impure anodes in sulphate based electrolysis is discussed. The first part is introduced with practical examples, the .model of solidification of impurities during the solidification of anode copper. According to this model the solidification structures of anode copper are strongly influenced by both thermodynamic and kinetic factors. Thermodynamics determine the microstructure of anode copper, but kinetics can alter the composition of melt to such that there is formed unequilibrium structures during the solidification, especially when the residual melt is solidified. The electrolysis experiments have clarified the behaviour of impuririties in the electrochemical dissolution in sulphate. Based copper electrolysis. In this study it is widely investigated to what extent any impurity elements or oxides will dissolve. In copper electrorefining. With the aid of the electrochemtcal experiments it was possible to fulfil quantitatively the qualitative results accomplished by microstructure studies.

Jan 1, 1985

By K. Soldenhoff

The Bulong deposit, situated near Kalgoorlie in Western Australia and owned by Resolute Limited, is a lateritic deposit containing on average 1.1% nickel and 0.09% cobalt. A process has been developed and tested at the mini-plant scale for direct solvent extraction and separation of Co and Ni from solutions derived by acid pressure leaching of Bulong ore. In this paper, two solvent extraction processes are described. The first process uses Cyanex 272 to extract cobalt and reject nickel to the raffinate. The second process uses Versatic 10 to extract and purify nickel. The loaded strip nickel solution is suitable for electrowinning. Results of both batch laboratory tests and continuous mini-plant trials are presented. The selectivity of the solvents with respect to the major impurities such as Mn, Mg, Ca, and Zn is also discussed.

Jan 1, 1998

By Evan Jamieson

The conditions under which various iron(III) oxy-hydroxides phases precipitate from iron(III) chloride and sulfate solutions at ambient temperatures (<60°C) are reviewed. Many of these precipitates are slow settling and gelatinous but ultimately transform into other more stable or crystalline phases. The phase that forms depends upon the rate of precipitation and pH. A comparison has been made of the iron(III) oxides formed upon the neutralisation of various iron(III) solutions with caustic, slaked lime or slaked magnesia which provide different rates of neutralisation and slowly dissolving solids with localised high pH. Mössbauer spectra of ferrihydrites precipitated under these different conditions are compared and interpreted. Particular attention is paid to the settling rate and settled volume which is likely to relate to industrial thickener and filter performance. It is shown that in pure chloride solutions, poorly settling ferrihydrite is usually produced at 20oC regardless of the choice of base. However in sulfate solutions fast settling precipitates are produced using lime and magnesia but not with caustic. In mixed chloride/sulfate solutions, optimum settling rates occur when the molar ratio of [SO4]2to Fe3+ is about 1:1 and when the sulfate concentration is <0.20 M. It is proposed that ?dense amorphous basic iron sulfate? or well-ordered ferrihydrite is formed on slowly dissolving lime or magnesia surfaces. Implications for industrial liquors are considered.

Jan 1, 2003

By Toshihiko Emi

The quest for cleaner steel is driven by increasingly stringent requirements from the manufacturing and construction industries. Key issues are the occurrence and removal of inclusions; These are discussed in the context of the unit processes of deoxidation, refining, transfer and casting of molten steel. Process thermodynamics and kinetics are also discussed. Recent progresses achieved and problems yet to be solved are elaborated, and an integration of the unit processes into a system to produce extra clean, steels with better performance is presented.

Jan 1, 1999

By Wander. L. Vasconcelos, Virgínia. S. T. Ciminelli, Angela. M. F. Guimarães

"The present work was aimed at synthesizing nanostructured hybrid materials derived from the functionalization of smectite clays with ligands containing thiol (-SH) groups for application in cadmium adsorption processes. An in nature Brazilian bentonite was investigated. The modification route was based on the grafting reaction between hydroxyl groups present on clay surface and the hydrolyzable alkoxy group of the (3-mercaptopropyl)trimethoxysilane in dry toluene under reflux. The present work showed that the proposed modification route was effective for the grafting of the thiol groups in the clay structure. The thiol-functionalized bentonite samples showed average binding capacities 160% higher with respect to Cd2+ to those obtained with the ungrafted material. These results support a mechanism of adsorption involving primarily ion complexation by the thiol groups (specific) instead of cation exchange (unspecific). The proposed modification processes are suggested for the preparation of novel adsorbent materials with controlled selectivity and specificity and therefore with good potential for separation and pre-concentration purposes.IntroductionMany efforts have recently been devoted to the design and preparation of inorganic-organic nanomaterials because of their potential application in novel functional materials. The intercalation of organic species within the spaces between interlayers of inorganic layered crystals provides nanostructures consisting of alternating layers of inorganic and organic compound. The intercalation reactions occur by insertion of mobile guest species (neutral, molecules, or ions) into the accessible crystallographic-defined vacant sites located between the layers (interlayer spacing) of the layered host structure [1}.Silane coupling agents, used widely for the modification of silica surfaces, have also been employed more recently for modification of layered silicates [2,3,4,5]. Modification with organosilane involves grafting reactions by establishing covalent bonds between the reactive groups of the layer, normally hydroxyl groups, and silane molecules. These reactions can be restricted to the external surface (the basal spacing remains unchanged) or to the interlayer surface, in which case an interlayer expansion occurs. The resulting material can be defined as a hybrid material or, more specifically, functionalized inorganic layered material [1]."

Jan 1, 2008