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By A. R. Farkoosh, K. Korgiopoulos, McGill University, O. Rodop, L. A. Villegas Armenta

"New generation of Al-Mg-Si alloys with thermally stable dispersoids that prevent recrystallization and grain growth during hot deformation are currently used in automotive components requiring good formability. Alloy chemistry controls the phase formation especially age-hardening precipitates, dispersoids, and primary intermetallic which have pronounced effect on grain structure, strength and formability. In this work, thermodynamic calculations have been used to predict the effects of varying levels of Si (0.5-1.5wt%), Mg (0.5-1.5wt%) and Mn (0.1-2.5wt%) on phase selection. Thermodynamic calculations have been performed in equilibrium and non-equilibrium conditions via the FactSage™ software using the FTlite database. Selected compositions have been cast, heat treated, extruded and characterized through scanning electron microscopy with energy dispersive spectroscopy and electron channeling contrast imaging techniques. The calculations showed that at the hot deformation temperature of ~540 oC, exceeding certain Mg and Si levels would lead to retained *-Mg2Si intermetallics and Si particles at the grain boundaries in addition to a-Al-(Mn,Fe)-Si. It was found that retained *-Mg2Si phase which adversely affects formability can be avoided for Si+2Mg levels lower than 2.3wt%. FactSage calculations also showed that increasing Mn from 0.5wt% to 1wt% leads to an increase in the amount of dispersoids (from 1wt% to 2wt%) that can potentially slow down recrystallization and grain growth during hot deformation and improve formability. Calculations at room temperature also show that for an alloy with 0.7wt% Mg, excess Si beyond 0.7 wt% promotes the precipitation of Si clusters in the Al matrix that accelerate natural age-hardening. Results were confirmed by experimental investigation.INTRODUCTIONAluminum alloy 6082 (Al-Mg-Si) is used in the automotive industry because of its high strength, and good weldability (I. J. Polmear, 2006). The alloy is age-hardenable through the precipitation of ß-Mg2Si and its precursors, and the recrystallization is usually inhibited by Mn- and Cr-containing dispersoids formed through high temperature heat treatments (I. Polmear & Couper, 1988). However, it is known that minor changes in alloy chemistry (Mg/Si ratio) can have significant influences on the ductility and formability of these alloys by altering phase selection and the resultant microstructure (Gupta, Lloyd, & Court, 2001; McQueen & Celliers, 1997; Zajac, Hutchinson, Johansson, & Gullman, 1994). For automotive applications where wrought alloys (usually extrusions) are cold-formed to produce suspension components, the chemistry of the alloys and the extruded structure are of crucial importance as they determine the formability at room temperature (Asensio-Lozano, Suárez-Peña, & Vander Voort, 2014). In this study, thermodynamic calculations along with experimental investigations were carried out on the Al-Mg-Si system to understand their phase formation and precipitation hardening as a function of alloy composition."

Jan 1, 2016

By Junhyun Choi, Allan Gomez-Flores, Chonbuk National University, Siyoung Q. Choi, Gahee Kim, Seungkon Kim

In this study, to confirm the effect of depletion attraction on the flotation, we theoretically and experimentally investigate the effect of the depletion attraction force on flotation. While varying the concentration of the depletion agent (polyethylene glycol), three different systems are studied: pure malachite, pure silica, and a 1:1 mass ratio of malachite and silica binary system. We find that recovery increases significantly as the concentration of the depletion agents increases for all three systems, as the depletion agent facilitates the adsorption of the particle on the bubble surface. However, the recovery suddenly decreases in a certain concentration range, which corresponds to the onset of the decreased surface tension when high concentrations of the depletion agent are used. This non-monotonic overall recovery trend implies the surface adsorption of the depletant on a surface. The decreased surface tension of the air/water interface suggests that the recovery rate is lowered due to the adsorption of the depletion agent to the bubble surface, acting as a polymer brush. Based on our observations, we conclude that the depletion force can greatly improve particle adsorption, as predicted in the accompanying theory paper, while simultaneously the adsorption of the depletion agent on the bubble surface plays an important role because it hinders particle adsorption. We also perform experiments in the presence of a small amount of a collector, sodium oleate. An extremely small amount of the collector leads to the increase in the overall recovery, which eventually reaches nearly 100 percent. Nevertheless, the grade worsens as the depletant provides the force to silica particles as well as target malachite particles.

Jan 1, 2016

By D. E. G. Maschmeyer

The operation of the pilot plant for the S-C Copper Process during 1976 has provided the basic data for the design of a commercial-scale plant. This paper introduces the commercial aspects of the S-C Copper Process through the presentation of a process flow diagram, a schematic flow diagram and basic design parameters for 75,000 tonnes per year (tpy) copper rod production from chalcopyrite concentrate. Basic operating requirements are outlined and a preliminary estimate of operating and capital costs for a Western Canadian location are summarized. The results have been compared with a modern smelter/electrorefinery to highlight the advantages and disadvantages of these two alternatives and to show why the new S-C Copper Process technology should be of interest to the copper industry.

Jan 1, 1978

By W. A. Green

To those who may not be familiar with the history and organization of the Flin Flon mining property from the rime of its examination and option by the Harry Payne Whitney interests until the present start of operations by the Hudson Bay Mining and Smelting Company, Limited, this paper may give a better understanding of the property. More technical discussions are being presented to you by the men most closely connected with the various operations of the property. Location The Flin Flon mine is situated along the boundary line between the Provinces of Manitoba and Saskatchewan at approximately. 54° 45? north latitude, but largely in Manitoba. Prior to the advent of the railway, the property was quite isolated. The summer route was over a course of some 175 miles, consisting of a 125-mile boat trip from The Pas, first up the Saskatchewan river, then across Cumberland and Sturgeon lakes to Sturgeon? Landing. From Sturgeon Landing, a .16-mile portage was necessary to Camp 2 on lake Athapapaskow. From Camp 2 the route consisted of a canoe trip of 32 miles across lake Athapapaskow, up the northwest arm of Schist lake, then up Ross creek to the Company's docks, and finally a 2-mile walk to the property. The winter route was just under 100 miles in length, the difference being due to the fact that a more direct route could be followed over the frozen lakes. It went up the Saskatchewan river for a short distance above The Pas and then, leaving the river, the road followed Reeder, Rocky, and Sturgeon lakes to Sturgeon Landing, and from there over the same route as the summer one, only across the frozen lakes.

Jan 1, 1930

By J-S. Marois, F. Cappucitti, Y. Dodier, D. Downey, G. Matton

"The flotation processes of the Niobec Mine have been affected by a seasonal loss of recovery and a significant increase in reagent consumption over the past few winters. This paper discusses the problem-solving methodology that was used to identify the root causes, to develop solutions and to implement changes that resolved the problem to restore the process to summer-like conditions year-round. Mainly, it was found that the process water was contaminated by phosphates ions, which adversely affected the carbonate pre-flotation, and caused detrimental effects on the subsequent niobium flotation. The phosphate ions were being generated by the process itself, but were consumed by algae in summer conditions. It was determined in laboratory studies that concentrations as low as 5 ppm were enough to affect the circuit and that the multiple additions of process water throughout the circuit was worsening the effect. Also, temperature was found to have an impact on the reagent performance. The performance of the plant was restored by implementing a natural treatment of our process water with a simple cost-free rearrangement of our circuit streams. In addition to that, our extensive geometallurgical program was used to provide ore to the plant restricting phosphate generation in the process. Also, a modification of the collector was developed and introduced in the carbonate pre-flotation that provided improved performance during the periods of low pulp temperature.INTRODUCTION Niobec is one the three major global producers of niobium presently in operation. Situated in the Saguenay-Lac-St-Jean region of Quebec and in operation since 1976, the site produces ferroniobium (FeNb) to be used mainly in High Strength Low Alloy (HSLA) steel, which is known to have better mechanical properties than carbon steel. The Niobec operation consists of an underground mine, a concentrator and a converter plant. The concentrator concentrates niobium-bearing minerals, mainly pyrochlore and columbite, to produce a high-content Nb2O5 concentrate which is then converted to FeNb in the converter plant by an aluminothermic reaction. The Niobec concentrator flowsheet, which has gone through many expansions and optimisation over the years, consists of grinding, desliming, flotation and leaching steps. The flotation steps are numerous, sensitive and difficult to operate due to the non-selective nature of oxide mineral collectors. Thus, the pyrochlore concentration process at Niobec still faces many challenges and is constantly going through periods of continuous improvement."

Jan 1, 2018

By Mark Holdsworth

In 2002, Kennecott Utah Copper Copperton Concentrator installed an Expert Control system for optimization of their SAG and Ball milling circuits. The advanced process control has been well received and is utilized well over 95% of the time. In the years since, many lessons have been learned and many advances have been made. Improvements have produced millions of dollars of benefits and have included directly controlling feedrate with complex logic as opposed to using a bearing pressure controller, modifications to how sound is used for control, modifying logic for maximizing asset utilization and using advanced control for automating equipment restart.

Jan 1, 2012

By T. Johnson, K. Lambrych, D. Kelley

Materials for construction of equipment used in hydrometallurgical plants are selected based on a combination of their ability to perform as required in aggressive process environments as well as their cost. As a material of construction, fiber reinforced plastic (FRP) has been shown to provide equal if not improved durability relative to alternative materials such as corrosion resistant alloys at a considerably lower cost. This is particularly true in the case of equipment used in acid leaching processes for copper, cobalt, nickel and rare earth elements. The selection and extensive use of FRP over alloys in new hydromet plant construction in North and South America illustrates this advantage of FRP effectively. This paper will compare corrosion performance and cost of plant equipment fabricated with stainless steel alloys and FRP made with Epoxy Vinyl Ester thermoset resins. Real world case histories for FRP piping, storage tanks, extraction vessels, and electrowinning cells combined with laboratory based corrosion studies will be reviewed to demonstrate how FRP materials are selected for hydrometallurgical equipment.

Jan 1, 2015

By K. Lascelles

ABSTRACT Nickel compounds vary significantly in their toxicological properties, so it is critical that continuing studies to accurately quantify worker exposures consider the processing that accompanies refining nickel-containing materials. The Clydach nickel refinery, which has operated for more than 100 years, was the first nickel-producing facility to show a high risk for lung and nasal-sinus cancers among workers employed since it opened in 1902. Process chemistry and equipment have changed dramatically over Clydach’s history. This paper describes the processing evolution at Clydach with a focus on the propensity for aerosol formation and the forms of nickel in airborne dusts.

Jan 1, 2013

By A. Brian Hawkins

"When pyrite oxidizes in dark grey/black, calcareous, mudrocks or in argillaceous limestones, ferrous sulfate is formed and sulfuric acid is released. The sulfuric acid combines with the calcite present in the rock and calcium sulfate (gypsum) develops. When this occurs on the outer edges of aggregate particles, the gypsum forms in the matrix hence there may be little expansion of the general material. However, when the chemical reactions occur within the rock fragments, particularly on microscopic, clayrich, laminae, the developing crystals exert a significant pressure on the host material. If the rock is medium strong to strong, the force of crystallization splits the rock along the weaker planes, facilitating the ingress of the oxidizing agents and the continuation of the chemical reactions. In addition to causing dilation/heave, some of the engineering properties of the material are changed, including the strength, Los Angeles value, water absorption etc. As a consequence material, which at the time of quarrying would be acceptable for use beneath floors or hardstandings, would no longer be considered suitable.INTRODUCTIONMudrocks accreting in aerobic environments are frequently disturbed by organisms and as a consequence there is often little sign of bedding. In contrast, sediments which have formed in anoxic environments commonly have distinct bedding planes which, because of the grain size of the accreting material, are often smooth and planar. These rocks are frequently referred to as shales, which O’Brien and Slatt (1990) define as “characterised by a finely laminated structure, which imparts a fissility approximately parallel to the bedding.” This should not be confused with rhythmic bedding where the variation in grain size results in lithological laminations or colour changes.Early geologists, in the stratigraphic naming of rocks, often used the term shale for material which is now more likely to be described as mudstone or mudrock (Hawkins and Pinches, 1992). In many contexts, the width of the bedding is an important factor, not only in determining the rock name but also in indicating the potential engineering characteristics. Until recently a shale was considered to have bedding separations of less than 20mm, i.e. the bedding was described as laminated. However, in an engineering context, EN 14689: 2003, Annex A, defines shale by specifying a bedding thickness of < 6mm; such a material would be described as thinly laminated in BS 5930:1999. Ideally the term shale should be abandoned and be replaced by fissile mudstone or fissile mudrock."

Jan 1, 2015

By J. Esson, R. A. D. Pattrick, M. K. Nimfopoulos, D. A. Polya, K. M. Michailidis

"Economic Mn-oxide ore deposits of commercial grade occur in the Rhodope massif near Kato Nevrokopi in the Drama region, Northern Greece. The Mn-oxide mineralization has developed by weathering of continental hypogene rhodochrosite-sulphide veins. The vein mineralization is con-?ned by tectonic shear zones between marble and metapelites, extending laterally into the marble astabular, pod or lenticular oreshoots (up to 50 m x 20 m x 5-10 m). Supergene oxidation of the hypogene mineralization led to the formation of in-situ residual Mn-oxide ore deposits, and secondary infills of Mn-oxide ore in embryonic and well developed karst cavities.Whole rock geochemical pro?les across mineralized zones con?rm the role of thrusts and faults as solution passageways and stress the importance of these structures in the development of hydrothermal and supergene mineralization at Kato Nevrokopi. Three zones are recognized in the in-situ supergene veins: (A) a stable zone of oxidation, where immobile elements form (or substitute in) stable oxide mineral phases, and mobile elements are leached; (B) a transitional (active) zone in which element behavior is strongly in?uenced by seasonal ?uctuations of the groundwater table and variations in pH-Eh conditions; and (C) a zone of permanent ?ooding, where variations in pH-Eh conditions are minimal. Zone (B) is considered as the source zone for the karst cavity mineralization. During weathering, meteoric waters, which were CO2-rich (PCO2~10-3.8 to 10-1.4) and oxygenated (fO2~10-17 for malachite), percolated downward within the veins, causing breakdown and dissolution of sul?des and marble, and oxidation of rhodochrosite to Mn-oxides. Karst cavity formation was favored by the high permeability along thrust zones. Dissolved Mn2+was transportedinto karst cavities in reduced meteoric waters at the beginning of weathering (pH~4-5), and as Mn(HCO3)2in slightly alkaline groundwaters during advanced weathering (pH~6-8). Mn4+-oxide precipitation took place by fO2increase in ground waters, or pH increase by continuous hydrolysis and carbonate dissolution. In the well developed karst setting, some mobility of elements occurred during and after karst ore formation in the order Na>K>Mg>Sr>Mn>As>Zn>Ba>Al>Fe>Cu>Cd>Pb."

Jan 1, 1997

The steam-filtration process for dewatering solids involves the application of slightly superheated steam to a filter cake during filtration. The mechanism by which the technique promotes water removal has been deduced from bench-scale experiments on coal and on granular iron ore concentrates. The mechanism, along with some of the applications and limitations of the process, is presented. Introduction I N the steam-filtration process, slightly super-heated steam is applied to the filter cake during filtration to remove more water than can be extracted by conventional filtration. Although this process was developed by Burton for coal filtration (1), it should have far wider applicability; certainly, it could be used to treat any mineral product, because only low-temperature steam is needed and most conventional filtration equipment can be easily adapted to it. As few restrictions apply to this process, however, it is important that its more obvious advantages and disadvantages be appreciated and, especially, that the criteria on which economic evaluations can be based are understood.

Jan 1, 1965

By C S. Stevens

This paper describes the problems encountered and the steps taken to solve them in milling an ore containing relatively large amounts of pyrrhotite. A complex and greatly lengthened flotation circuit was required to recover the pyrrhotite. A very low pH had to be maintained in the cyanide circuit in order to get good recovery of the gold and maintain reasonable cyanide recovery. Introduction D ELNITE Mines Ltd., a gold mine situated about 5 miles by road south and east of the town of Timmins, Ontario, is serviced by two shafts. No. 2 shaft extends from surface to the 2875-ft. level, and No. 3 shaft, an internal winze, extends from the 2875-to the 5275-ft. level. No. 2 shaft was stopped at the 2875-ft. level because of a heavy band of chloritic schist which necessitated a drive to the north for 1000 feet, where No. 3 shaft was sunk. The latter bottomed in the schist at the 5275-ft. level. From the 2500 to the 2875-ft. level in No. 2 shaft, the ore was

Jan 1, 1965

By Qing-hua Tian, Li-then Cheng, Xue-yi Guo

In order to recycle valuable metals from silver separated residue, a novel method using alkaline smelting at low temperature was proposed. The main factors affecting the main metal recovery such as the smelting temperature, smelting time, liquid-to-solid ratio and alkali addition were investigated comprehensively. The behavior of the main metal elements, such as Pb, Sn, Sb and Bi in silver separated residue was also discussed. The results indicated that amphoteric metals such as Pb and Sn can be smelted into the melt, while other metal elements, such as Sb and Bi were left in the residue.

Jan 1, 2011

By Linlin Tong, Xiangling Song, Guobao Chen, Zhenan Jin, Hongying Yang

Biooxidation of a high arsenic-bearing refractory gold ore was investigated to determine the arsenic removal efficiency by the cultured bacteria and to examine the effect of biological pretreatment on subsequent gold cyanidation. The biooxidation pretreatment process utilizes the ability of adapted acidophilic bacteria to oxidize pyrite and arsenopyrite and release the encapsulated gold. The released gold can be efficiently extracted by the subsequent cyanidation process. The biooxidation experiments were conducted with cultured bacteria using various sizes of agitation tanks. Leaching results showed that over 96.26 % arsenic extraction could be obtained from this ore after 6 days of bioleaching with continuous stirred tank reactor (CSTR). Gold extraction during the cyanidation process was increased from 29.35% to 96.71% after biological pretreatment. The content of arsenic in the biooxidation residue was reduced to below 0.3%. The transformation process of As was considered as [AsS]2- ? As (?) ? As (?) during the biological pretreatment.

Jan 1, 2014

By J. Ipinza, J. P. Ibáñez, Casas J., S. Cortés

Copper powder generated during the treatment of electro-metallurgical bleeds by reactive electro- dialysis (RED) had totally reduced the content of ferric ions in acidic synthetic electrolytes (Cu (II)- Fe (III) – H2SO4). In batch and columnar experiments 100% of the ferric ions were reduced to ferrous ions with an extremely high kinetics. A preliminary conceptual design for reducing ferric ions based on an integrate RED- Column for treatment of electro-winning bleed system is discussed. This system is able to recover simultaneously sulfuric acid and copper powder, which will reduce ferric ions. INTRODUCTION It is well known the negative effect of ferric ions in the copper electro-winning process. The increase of ferric content in the electrolyte reduces the current efficiency, i.e., there is an increase in the energy consumption, and changes the surface morphology of the copper deposit (Das, Gopala & Krishna, 1996; Vargas & Parra, 2013). The increase of the specific energy consumption due to the loss of current efficiency occurs by the reduction reaction of ferric to ferrous ions in the cathode, at the anode the ferrous ions are slowly oxidized to ferric ions (Shaw, Dreisinger, Lancaster, Richmond & Tomlinson, 2004). To control the level of iron in the electrolyte, bleeds are needed; this bleed electrolyte containing copper, sulfuric acid, cobalt, iron and other impurities normally is waster, which increased the production cost of the plant (Milbourne, 2002; Mckevitt & Dreisinger, 2009). Then, permanent efforts oriented to treat those bleeds to avoid losses of valuables components are made; among them are use ion exchange resins (Shaw et al., 2004; Mackevitt et al., 2009), chemical precipitation (Izadi, Mohebbi, Amiri & Izadi, 2017) and electrodialysis (Cortés, Ipinza & Ibáñez, 2013). The last one allows to the simultaneous recovery of sulfuric acid and copper powder. If one of the valuables obtained by treating the bleed can be used to reduce ferric ion concentration in the electrolyte could be an important asset. This issue at laboratory scale is reported in this work, the use of copper powder, generated by reactive electro-dialysis when treating synthetic acidic electro-metallurgical bleeds, for reducing ferric ions in acidic electrolytes.

Jan 1, 2019

By H. J. White

The effect of alloying elements on the mechanical properties and weldability of wrought gamma prime strengthened nickel- base superalloys is well known. An understanding of the basic guidelines concerning alloying additions has led to the invention and development of HAYNES® 282® alloy for applications in aircraft and land base gas turbines and other high-performance high-temperature environments. The alloy combines exceptional high temperature properties with good weldability and fabricability. At high temperatures (~ 900 °C), the alloy is stronger in creep strength than Waspaloy alloy (UNS N07001) and it approaches the creep strength of R-41 alloy (UNS N07041). Because the alloy has better thermal stability, fabricability, and weldability than Waspaloy and R-41 alloys, it is currently being considered as a candidate universal consumable for welding/ repair welding of gamma prime strengthened nickel based superalloys and it is also being considered as a suitable replacement for applications where R- 41, Waspaloy, and 263 (UNS N07263) alloys are currently being used. The alloy was designed to have improved resistance to strain age cracking, a problem common to gamma prime strengthened nickel based superalloys. In this paper, we present (1) results from hot ductility testing of annealed and annealed/aged material; (2) results from Time Resolved X-ray Diffraction (TRXRD) studies during a welding thermal cycle of annealed and annealed/aged material, and (3) gas metal arc (GMA) and gas tungsten arc (GTA) welding of annealed and annealed/aged material.

Jan 1, 2010

By A. Pawelczyk, D. Hreniak, E. Zych, W. Strek, K. Grabas, A. Ostrowski

"Mongolia is a country rich in rare earth resources. In the experiments carried out samples of the Mongolian ore were processed to obtain a lanthanide concentrate. The concentrate underwent hydrometallurgical processing. At the same time radioactive elements were removed. The lanthanides were obtained in the form of hydroxides that were further processed in order to get concentrated products. As a result cerium, lanthanum and neodymium-praseodymium concentrates were separated in the process. Also a concentrate of remaining elements: samarium, europium, gadolinium, terbium, dysprosium, holmium and erbium was obtained. INTRODUCTIONAccording to the assessment of the US Geological Survey, Mongolia possesses 16.77 % of the world total rare earth (RE) resources (Daly, 2011); that is the second largest RE reserve in the world, estimated to be 31 million tonnes in terms of rare earth oxides (REO). In the face of Chinese RE trade restrictions, Mongolia emerged as an important economical partner in mining and exploitation of these critical raw materials. This country is recognized as having more than five large RE deposits in the southern provinces. The most important are Lugeengol (Lugin Gol), Mushgia Khudag, Khotgor and Khalzan Buregtei (Eurasia, 2010). The Mongolian government has taken measures to facilitate western investments, nevertheless the country is economically dependent on China, the basic trading partner, particularly where exports are concerned.In the late 1970s Hydromet Kowary Enterprise, Poland, took up, along with the Wroclaw University of Technology, research and technological study on lanthanides recovery from raw materials of Vietnamese and Mongolian origin and from Indian monazite sands (Kowalczyk, 1990; Kowalczyk & Mazanek, 1987; 1990). For that purpose, a rare earth processing plant had been constructed with the capacity of about 10 t/year of hydroxide concentrate. The facility included several technological operations like grinding, flotation, hydroxide concentrate production in the hydrometallurgical processing, particular RE separation, and production of commercial products in form of CeO2, La2O3, Nd2O3, Pr2O3, and misch metal. Additionally work had been carried out in Kowary on the manufacture of yttrium and europium oxides of high purity, which were intended for color TV picture tube production in Poland."

Jan 1, 2012

By Zihe Ren, Edouard Asselin, Marcus Tomlinson, Tianbi Zhang, Jing Liu

"Raman spectroscopy is used to quantify the extent of disorder in the carbonaceous matter associated with preg-robbing ores. Previous studies of Goldstrike ores showed that the height and width of the peaks for the “D” (disordered) and “G” (graphite) bands, the so-called “Raman ratio” had a strong correlation to the preg-robbing value (PRV) measured for various ore samples. A brief literature review on Raman spectroscopy as it applies to preg-robbing ores is presented. Further, recent studies, presented here, have shown no correlation between the Raman ratio and the PRV for a wide variety of ores. This suggests that the extent of organic carbon crystal disorder is not the main factor in determining preg-robbing characteristics.INTRODUCTION Preg-robbing may arise from natural carbonaceous materials in the ore. Several mechanisms have been proposed in the past decades including a physical sorption process by the carbonaceous matter, or via the reduction of aurocyanide at the mineral surface (Abotsi & Osseoasare, 1986; Afenya, Osseoasare, & Abotsi, 1983; Tan, Feng, Lukey, & Van Deventer, 2005). Nevertheless, the mechanisms of preg-robbing remain poorly understood. Understanding the nature of the preg-robber is of practical importance for the selection of a suitable treatment process. Fine carbon particles in the ore have been recognized as preg-robbers due to their similarity to the activated carbon used in the carbon in leach (CIL) or carbon in pulp (CIP) processes. Previous research has illustrated that the activated carbon (also referred to as amorphous carbon in some literature) has a much higher absorption ability than pure graphite with high crystallinity (Adams & Burger, 1998). Adams et al (Adams, Swaney, Friedl & Wagner 1996) concluded that carbonaceous matter is largely responsible for the overall preg-robbing capacity of a given ore. However, the mechanism of carbon preg-robbing was still not clear mostly due to the complexity of amorphous carbon and its behavior in different solution matrices, and at different pH and temperature (Adams, 1990, 1993)."

Jan 1, 2017

By Rodrigo Serna-Guerrero, Ted Nuorivaara

"As the demand of raw materials increases in a global scale due to demographic and economical changes, it is necessary to find technological solutions that improve current production processes in an efficient and sustainable manner. The main objective of this preliminary study is to evaluate the properties of foam produced with a cellulose-based molecule as an alterative to commercial frothing agents in flotation operations. There are two potential advantages identified with the use of cellulose-based additives for the proposed application: i) these chemicals can be produced from sustainable sources (i.e., non-edible crops), and ii) cellulose can be functionalized with chemical groups, in order to rationally modify its behaviour. In previous studies dealing with foam stabilization, it has been proposed that some functionalized cellulose species present a self-assembly mechanism at gas-liquid interfaces. Unlike typical surfactant-based frothers, cellulose molecules form networks around the bubbles that act as protective layers to the mechanical stress and to the occurrence of ionic species. This work studied the properties of foams produced in the presence of a partially hydroxylated cellulose molecule (i.e., hydroxypropyl methyl cellulose; HPMC) under various concentrations in a laboratory-scale column. A comparison with a commercial surfactant frother (i.e., Nasfroth 240) is presented, and a rationalization of the behaviour of HPMC in terms of foam properties (i.e., surface tension, bubble size, foam depth) is proposed. INTRODUCTIONThe search for green alternatives to chemicals produced from non-renewable sources has become a topic of major relevance in industry (Choi et al., 2015). As a chemical consuming industry, the mining sector faces now the challenge of adopting new processing technologies and strategies in order to achieve the future demands of sustainability. Evidently, a move towards green chemistry can only take place by identifying substitute molecules offering potential advantages in terms of recovery and grade."

Jan 1, 2016

By Yongjie Bu, Wei Sun, Zhiyong Gao, Yuehua Hu, Hongbiao Tao, Runqing Liu, Central South University

"The flotation behavior of O-isopropyl-N-ethyl thionocarbamate (IPETC) and pH for chalcopyrite and galena was studied through pure mineral test, adsorption quantity determination, solution chemistry calculation and Materials Studio simulation. The results show that the recovery differential value of chalcopyrite and galena is about 20% when pH of the pulp 9.5 and IPETC is 7×10-4 mol/L, the flotability differences of the two minerals is significant. There is competitive adsorption between OH? and IPETC on mineral surfaces, it lead to galena flotability is lower than chalcopyrite flotability. IPETC can remove the hydration layer on mineral surface and adsorb on active sites for collector adsorption, minerals have a better hydrophobicity.INTRODUCTIONCopper and lead are two of the most widely used metals in industrial and living, their applications include building construction, various metal alloys, heat and electricity, machine manufacturing (Zhang et al., 2014). Chalcopyrite and galena are the major source of copper and lead, normally they associated with each other. With the growing use of these resources, high grade and dissemination large particle sizes minerals are less and less, the use of low grade and complex dissemination minerals have to be paid more attention (Chen, Ye, & Li, 2010; Liu, Sun, Hu, & Wang, 2009). As the special properties and complex composition of copper-lead sulfide ore, flotation separation of chalcopyrite from galena effective is a research emphasis and difficulty point in mineral processing (Bruckard, Sparrow, & Woodcock, 2011).In the separation process of chalcopyrite and galena, it is rather important to choose effective collector (Huang, Wang, & Liu, 2014). Enlarging and using the two mineral flotability will be a good basis and start in flotation (Reyes-Bozo et al., 2014). Qin et al. (2013) made a great deal of research on flotation separation of copper/lead concentrate, collector O-isopropyl-N-ethyl thionocarbamate (IPETC), butyl xanthate (BX) and ammonium dibutyl dithiophosphate (ADTP) were investigated, BX and ADTP floated both chalcopyrite and galena well, specific adsorption appeared in the surface of mineral, the problem was the collectors were not selective enough, however IPETC showed better selective."

Jan 1, 2016