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By G. Deschenes

"This literature survey discusses the recovery of gold from thiourea solutions. An overview of techniques used and general comments on the basic cyanidation methods are presented. The chemistry and mechanisms of cementation, activated carbon, resins, electrowinning, solvent extraction and pressure reduction are examined. Conclusions and recommendations give orientation for future research and development activities in this field.RésuméCette revue littéraire traite de la récupération de I ‘or des solutions de thiourée. Elle fait un survol de I ‘ensemble des techniques utilisées tout en introduisant des commentaires généraux sur la méthode classique qu'est la cyanuration. La cémentation, Ie charbon active, les résines, l'électroextraction, I ‘extraction par solvant et la réduction sous pression sont les méthodes analysées tout en considérant leur caractère chimique respectif ainsi que les mécanismes qui y sont rattaches. Des conclusions sont tirées et différentes recommandations sont suggérées pour orienter la recherche dans ce domaine."

Jan 1, 1986

By Ross G. Bertinshaw

"The Line Creek Mine of Crows Nest Resources started mining coal in the fall of 1981. There are seven mineable seams with thicknesses ranging from 1.5 to 13 metres and with dips varying from 0 degrees to 60 degrees. This, together with internal partings and the very friable nature of the coal, creates a number of mining problems.The coal is divided into zones depending on the dip of the seam. Each zone requires a different mining technique to ensure optimum recovery and low dilution while still keeping fines to a minimum.Line Creek employs a combination of hydraulic front shovels and backhoes to mine its coal without blasting or use of dozers. This has been very successful in reducing the proportion of fine coal hauled to the plant, thus improving quality control and reducing costs in coal processing.There have been a number of other benefits from the use of excavators instead of more conventional methods. These include better selectivity, good cleanup, reduction in traffic at the face and lower cost.IntroductionThe Line Creek Mine is situated approximately 25 km north of Sparwood in southeastern British Columbia (Fig. I). Preproduction stripping began in J98J with the first coal shipments made in 1982. In 1983 the mine produced 2.1 million tonnes of raw coal.Similar to other East Kootenay coals, the seams at Line Creek are characterized by their friability, producing a large proportion of fine coal during mining. In an attempt to reduce these fines Crows Nest Resources has instituted the use of hydraulic excavators to mine and load the coal.Hydraulic excavators offer other substantial advantages over front-end loaders and dozers, which has been the conventional system in other mines in the area."

Jan 1, 1985

By E. Adam, B. Milkereit, M. Salisbury, L. E. Reed, G. Perron

Integrating seismic reflection, borehole geophysical, and physical rock property studies is an effective means of mapping lithological contacts and structures in the crystalline crust. At Les Mines Selbaie in the northern volcanic zone of the Late Archean Abitibi Subprovince, a high-frequency seismic reflection profile has provided the first images of deep crustal structures of this important polymetallic mine site. Physical rock property and borehole geophysical studies confirm that prominent seismic reflections can be caused by lithological contacts, faults and sulphide mineralization. At Les Mines Selbaie, the first two of these are shown by this study. Clearly identifiable reflection images from sulphide mineralization have not been demonstrated in analysis of the profile. The seismic images provide useful information about gross structure in the vicinity of Les Mines Selbaie. They can also place important constraints on the sequence of tectonic events and, therefore, can aid future deep exploration programs.

Jan 1, 1997

By Tsuyoshi Adachi

Photovoltaic (PV) system is especially taken notice as one of important renewable energy resources, because PV has potential to provide a certain amount of energy supply as well as without greenhouse gases emission. Considering recent rapid increasing demand for PV system, more expansion of PV system is expected in the future. However, some precious metals and minor metals such as silver, indium and others are used as component materials of solar cell in PV system. Even if energy supply would become renewable, strict limitation of these metals still remain because amount of natural resources and recycling of metals has restrictions intrinsically. The aim of this study is to reveal the possibility of materials supply restrictions for Photovoltaic system quantitatively and to propose several measurements to assess supply risks for materials. Especially, silver supply potential which is used as wire line in PV system as well as PV demand forecast to estimate material use in the future are focused on. We divide underlying supply risk into 5 measurements and analyze them by time series, i.e. price volatility, resource potential, recycling ratio, production type and supply concentration are investigated. Comparing these factors of silver with other metals, the potential of silver supply for PV is presented. In addition to it, we propose another method to quantify country risk applied an insurance pricing model in finance pricing theory and combine it with the supply concentration measurement. As a result, supply risk of silver will increase gradually in the near future because of its resource constraints and supply-demand balances although silver market is sufficiency competitive one. From the country risk analysis, Peru is not only a significant supply country but also has the highest country risk. Some higher risk countries will increase the level of supply risk even if the concentration ratio of supply indicates moderate level.

Aug 1, 2013

By Mark Sherman, M. Dennis, Raj Rajamani

"The two Alumbrera 36ft (10.97m)dia. SAG mills were sized, using the FDW ""Grindpower 'I program, to treat an average of 1852 tph each. This paper describes how modelling of the shell lifter design, using the Millsoft program, identified milling inefficiencies caused by poor charge motion. This explained the ""as built"" circuit's inability to achieve the throughput rates predcted by the circuit's designer. Use of the Millsoft program to design a new, dramatically different lifter configuration, in conjunction with a different approach to variable speed drive utilization, has resulted in an improved charge motion and a 30% increase in hard ore milling rates. The new lifter design has allowed the designer's predicted average throughput rates to be achieved.IntroductionThe Alumbrera project grinding circuit consists of two 36ft dia. X 17ft EGL, 13 500 kW, variable speed, gearless drive SAG mills coupled to four 20ft dia. X 30ft EGL, 6 000 kW fixed speed, gear driven, ball mills. The circuit is configured as two identical grinding aisles, each consisting of one SAG mill and two ball mills. No pebble crushing circuit was installed due to the expected absence of a critical size fraction in the first years of production. However, the grinding circuit layout does incorporate space for a pebble crushing retrofit. At present, only about 5% - 10% of the new mill feed reports as trommel oversize and is recycled back to each SAG mill using a water cannon.The circuit was designed to be ball mill limited and to treat the four major Alumbrera ore types at rates varying between 68 000 tpd, and 89 750 tpd, depending on ore hardness. Average throughput rate, and hence nominal design rate, for the grinding circuit was 80 000 tpd (1 852tph per line at 90% availability)."

Jan 1, 1999

By K. Duckworth

"AbstractA new electromagnetic depth sounding technique was applied to the measurement of salt thickness above the workings in the Central Canada Potash Mine at Colonsay, Saskatchewan. The initial tests indicate that this new technique can measure salt thickness and that the technique possesses operational feature s which make it possible to monitor trends in salt thickness throughout the mine. The technique can be applied using existing equipment, but the tests do indicate the desirability of developing equipment with features specially suited to the mine environment.IntroductionTESTS were conducted in the Central Canada Potash Mine at Colonsay, Saskatchewan during 1974 and 1975 to determine if a new technique in electromagnetic depth sounding could provide a convenient means of measuring salt thickness above the workings. This new technique, which was described by Duckworth (1975), offers operational features which appear to be advantageous in this particular situation.The problem requires that soundings be made upward from the mine workings to the base of the second red shale. This shale forms an impermeable seal on top of the Prairie Evaporite. A knowledge of this salt thickness is of interest due to the need to avoid any possibility of the workings rising to cut the red shale. Another desirable objective is the detection of any disruptions of the red shale. Ideally, this should be done ahead of the workings in order that such areas of disruption may be avoided."

Jan 1, 1977

By J. E. Armstrong

"IntroductionT'HE PRODUCTION of gravel and sand may be considered to be the major mining operation in the Lower Fraser Valley of British Columbia. At least thirty pits are in operation with a yearly production probably in excess of two million yards and a value in excess of one million five hundred thousand dollars before crushing, washing, and sizing. The value of the finished products would probably be double the above figure.Since 1949, the writer and his co-workers have been engaged in the geological investigation of the Lower Fraser valley and adjoining Coast mountains for the Geological Survey of Canada. The study, which is not yet completed, includes both bed-rock geology and geology of the unconsolidated sediments lying above bed-rock. In a rapidly expanding industrial area, .an advance knowledge of the geology may• greatly aid in future 'planning, and in many cases may .prevent not only the wastage of large sums of money, 'but possible disaster. Some of the present and future applications in which geological information in the Lower Fraser valley should be of value are as follows: the development of domestic, irrigation, industrial, and municipal groundwater supplies; drainage for industrial sites,, roadbeds, and farmlands; flood control along the Fraser river and smaller streams in the area; the location of dam sites, of major tunnels for water supply •and sewage, of road-beds, of foundation sites for large buildings .and other engineering undertakings in which geology may aid; the evaluation of oil and gas •possibilities; the production of building stone; and the production of sand and gravel, the subject with which this paper is primarily concerned."

Jan 1, 1953

By S. Xu

Magnesium alloy AM50 is of interest to automotive cradle application because of it excellent castability and good ductility. In this work, microstructure and mechanical properties of both low pressure die cast (LPDC) and high pressure die cast (HPDC) AM50 test bars are characterized. Microstructure was examined using optical microscope, scanning electron microscope (SEM) and transmission electron microscope (TEM). Phase identifications were performed using energy dispersive x-ray spectrometer (EDS) and TEM diffraction. It has been found that LPDC produces much coarser microstructure than HPDC. At the same time, the HPDC samples are more heterogeneous in microstructure and composition close to grain boundaries. Particles with various dimensions and morphologies of two different intermetallic phases, Mg17A112 and A18Mn5, were found in all the samples. Mechanical tests were performed under conditions similar to those related to an engine cradle application. LPDC samples show lower strength but better creep resistance than HPDC mainly due to the difference in grain sizes and grain boundary microstructure between LPDC and HPDC. Creep curves are well described by the empirical Andrade equation. Tensile-compressive yield and creep asymmetries were found in AM50, i.e. better deformation resistance in tension than in compression. The average yield asymmetry ratio for all the samples is 0.87. Microstructural examinations on the samples tested in tension, compression and creep showed that the deformation mechanisms in AM50 were slip plus twining at temperatures up to 125°C. The examinations indicate the important role of twining in the asymmetry phenomenon. The creep results indicate that dynamic precipitation of the Mg17A112 phase during testing is not the mechanism directly responsible for the creep asymmetry in AM50.

Jan 1, 2004

By Michel Dostie

Un séchoir à vis chauffé par induction électromagnétique a été développé et implanté chez Mines Niobec pour le séchage d?un concentré de niobium. Ce séchoir a permis une réduction des émissions de poussières et des gaz à effet de serre de l?usine. Il offre une grande souplesse de contrôle, une meilleure efficacité énergétique et peut être utilisé pour le séchage de granulats, de poudres ou autres substances habituellement traitées dans un four rotatif ou à l?aide de vis chauffées par un caloporteur. Le principe de fonctionnement du séchoir est simple. Trois inducteurs opérant à la fréquence du réseau électrique assurent le chauffage des parties métalliques du séchoir, dont des vis qui servent à convoyer le matériel. Le contact du matériel avec les parties métalliques chaudes permet le transfert de l?énergie requise pour le séchage. La conception de ce type de séchoir requiert un équilibre adéquat entre les besoins associés au chauffage par induction et ceux liés au transfert de chaleur par contact et au transport du matériel dans le séchoir. Cette première implantation industrielle a nécessité des efforts de développements importants et une collaboration des différents intervenants. Une revue des principes de conception, des difficultés rencontrées et des performances obtenues sera présentée.

May 1, 2007

By N. R. Andrade-Gonzalez

The present work was performed on four alloys containing Al-6 2 wt pct Si-3 5 wt pet Cu, with magnesium in the range of 0.02-0 40 wt pct, and strontium in the range of 0-165 p p m Tensile bars were cast in a permanent mold (ASTM B108-160) and heat treated at 495°C for 4 hours, followed by quenching in hot water. Two different artificial aging temperatures were applied at 180 °C and 220 °C for times from 0 5 h up to 8 h Tests were conducted with the intent of determining how the mechanical properties of an aluminum-based 319 alloy are affected when aging time and temperatures are varied In general, it is seen that the alloy does not exhibit the common peak-overaged aging condition due to the presence of several coexisting phases, indicating that they form through complex eutectic reactions late in solidification.

Jan 1, 2004

By L. M. Pidgeon

Abstract The production of metallic calcium, by reduction of lime with aluminium, was investigated. Using a modified form of the effusion method, the vapour pressure of calcium above the reaction: 4CaO + 2Al ~ 3Ca + CaO.AI203 was determined and found to vary from 1.0 to 1.3 mm. Hg from 1,150° to l,200°C. From the magnitudes of the various thermodynamic quantities involved, together with a consideration of the known chemical characteristics of the reaction, it was suggested that the reaction proceeded by reduction of lime with aluminium vapour. INTRODUCTION The conventional production of metals by reduction of their ores by carbon (or carbon monoxide) may be represented by the equilibrium: MO+ R [] RO+ M . . . . . . . . . .(1) where MO represents the metal oxide, and R the reducing agent (carbon or carbon monoxide). The free energy change ?F° associated with the reaction is given by -?F° = RTlnKp . . . . . . . . ... . (2) where R is the gas constant, T the absolute temperature, and KP the equilibrium constant. It should be noted that ?F° represents ? the standard free energy gained by the system and hence -?F° is the free energy gained by the surroundings - and that as ?F° increases K must decrease, and conversely. For metals above manganese in the electromotive series, the ?F° associated with reaction would quantity and from it can be seen that this corresponds to a small fraction for K. The equilibrium pressure of the oxide of carbon represented by RO is then too near its concentration in the furnace gases for the reaction to proceed in an internally fired furnace. For the practical reduction of such metals, fuel fired furnaces are inadequate. Electric furnaces may be used to give higher temperatures with lower concentration of carbon oxides and the reaction may still proceed. However, for many metals such as calcium and aluminium the formation of stable carbides or acetylides may prevent production of the metal by this reaction. In this case, either electrolytic methods must be used, orrecourse must be had to reducing agents other than carbon. It is the latter method which is under consideration here.

Jan 1, 1948

By T. W. Wlodek

"AbstractIn this paper a new type of durable 'spiral-rolled' drill set is introduced and its performance discussed. Efficient and economical mine drilling-depends to a great extent on durability of the drill-set employed. Premature failure of this element damages the drill bit and is costly when tungsten carbide bits are used.Time of drilling of 'spiral-rolled' drill sets introduced at present in Canada is considerably larger than for the presently used drill steel, but laboratory simulated service tests and practical field tests show that the 'drilling life' of the spiral-rolled drill set is several times that of ordinary drill steel.Some features of differential plastic deformation and differential surface rolling, so called 'spiral-rolling', are given.Relations between the drilling machine drill set and characteristics of the ore are discussed. The effect of shims on conical drill rod attachments, the mechanism of failure of drill steel, .and stresses during mine drilling, are analysed.IntroductionIN MINE DRILLING operations, the main interests are: the drilling machines as a source of working energy, the drill set as the tool transferring the working energy to the cutting edges of the bit, and, finally, the drilling characteristic of the .ore or waste rock.This paper includes a review of the possibilities of metallurgical and mechanical improvements in the drill set, with particular attention to drill steel and the attachments.For economical and efficient mine drilling operations, a durable drill rod, attachment, and drill bit are essential. Premature failure of any of these parts interferes with mining operations and is costly."

Jan 1, 1955

Arsenic bearing minerals such as enargite (Cu3AsS4) and tennantite (Cu12As4S13), which may associate with major copper minerals such as chalcopyrite (CuFeS2), chalcocite (Cu2S) and bomite (Cu2FeS4), usually report to the copper concentrate in conventional flotation due to their similar flotation properties. Arsenic in a copper concentrate causes environmental problems and also problems in the subsequent pyrometallurgical process. Voltammetric studies were carried out to investigate the oxidation characteristics of enargite, tennantite, chalcopyrite, chalcocite and bomite. Contact angle measurements and micro-flotation tests were conducted to examine the flotation characteristics of enargite and chalcopyrite under controlled pulp potentials. Selective flotation of enargite from chalcopyrite under varied pulp potentials was conducted to investigate the feasibility of arsenic removal from a copper concentrate. The test results indicate that the non-arsenic bearing copper minerals ( chalcopyrite, chalcocite and bornite) were easier to oxidise than arsenic bearing minerals ( enargite and tennantite) in an alkaline solution. Enargite floated well at a potential as high as +0.45 V vs. SCE while chalcopyrite was completely depressed at a potential higher than +0.43 V vs. SCE. Selective flotation revealed that enargite can be successfully removed from chalcopyrite through controlling the pulp potential at +0.30 ~ +0.50 V vs. SCE.

Jan 1, 2007

By W. C. Zhu, C. H. Wei, L. L. Niu

With an increase of mining depth, a series of mining-induced hazards such as rockburst, coal and gas outburst, roof collapse, and water burst are getting more serious and more frequent. The intrinsic mechanism responsible for the occurrence of mining-induced hazards is the damage and unstable failure of rockmass or coal seam. The most distinct difference between deep and shallow levels is the so-called three ‘high’ (H3) conditions, i.e. high geo-stress, high fluid pressure and high geo-temperature. Therefore, the response of rock or coal to the deep mining operation is a phenomenon involving thermal (T), hydraulic (H), and mechanical (M) processes. Most importantly, mining excavation may vary the rock stress condition greatly, which may be a key factor to trigger the mining-induced hazards such as rockburst. In this regard, it is of great significance to clarify the damage and failure mechanism of rock and coal under coupled THM conditions, in order to clarify the rock failure mechanism responsible for the occurrence of mining-induced hazards. Thereafter, the mining-induced hazards cannot be predicted with confidence by considering each process independently. Of course, the requirement to include coupling of these processes depends on the specifics of the mining-induced hazards under consideration. For example, the water inrush is considered as a coupled hydro-mechanical (HM) process, in which the unstable failure of rockmass occurs under the combined contribution of geo-stress and water pressure. As for the coal mining at depth, in addition to high geo-stress and gas pressure in coal seam, the high geo-thermal condition that may greatly change the adsorption / desorption of gas and gas flow should be taken into account. Firstly, a general-purpose mathematical model for rock damage and failure process under coupled THM conditions is formulated based on damage mechanics principle, and it is solved by finite element method (FEM). In this model, the deformation and damage of rock, fluid flow and thermal transfer in rock would interact with each other, one process affects and initiation and progress of another. Then, the model is used to predict the mining-induced water outburst, where it is simulated as coupled hydro-mechanical (HM) problems. Based on the numerical simulation, the dimension of water-proof pillar is designed. Finally, the gas drainage from deep coal seam is numerically evaluated, where the coupled coal-gas interaction considering the effect of gas adsorption/desorption, gas flow in coal seam and geo-stress and geotemperature, is comprehensively taken into account. The proposed model could be used for clarifying the mechanism of mining-induced hazards in deep-level mining.

Jan 1, 2015

By M. Yamine, R. J. Ring, D. J. Waters

"An experimental program has been carried out by the Australian Atomic Energy Commission to compare the effectiveness of Caro's acid as an alternative oxidant to pyrolusite in the leaching of uranium ores from the Alligator Rivers region of northern Australia. Batch leaching tests on Ranger, Nabarlek, Koongarra and Jabiluka ores showed that uranium extraction was unaffected by choice of oxidant, but that Caro's acid reduced acid requirements by 15 - 25%. Lime requirements for neutralization of tailings liquors were reduced by 20 - 30%.The batch studies were extended to a four-stage continuous leaching circuit with a capacity of 400 gore h-I. Comparative leaching tests confirmed the reagent savings obtained in the batch tests. Following these encouraging laboratory results, lnterox Chemicals Pty Ltd carried out plant trials using Caro's acid. Reagent savings in the mill were similar to, or better than, those obtained in laboratory test work. The trials also established that Caro's acid has a number of operational advantages over pyrolusite.IntroductionUranium is most commonly extracted from its ores by leaching in sulphuric acid. Simple hexavalent uranium oxides and compounds are readily soluble but uranium in the tetravalent form is insoluble and must be oxidized for dissolution to occur. The most commonly used oxidants have been sodium chlorate and manganese dioxide. They act indirectly by maintaining iron as the ferric ion which oxidizes uranium by a surface electro- chemical reaction. An Fe3+ concentration of about 1 - 2 g L-I is usually considered adequate for the effective dissolution of uraninite(1)."

Jan 1, 1984

By H. Wilton Clark

"IntroductionTHE CANADIAN use of short-period delay-action detonators in coal shooting has been carried on for about two years, mostly in British Columbia, and this is a preliminary report on progress to date. Entire coal faces are being shot successfully with one application of electric current.The electric blasting cap came into use about the beginning of the century. The low-tension electric cap, the type most commonly used, consists essentially of a metal tube containing an initiating explosive. Two wires lead into the end of the cap and are connected inside the cap with a short 'bridge wire .of very high resistance. This •bridge wire is buried in a match-head of a readily ignitable powder composition. When current goes through the lead wires, the bridge wire becomes extremely hot and sets• off the match-head which, in turn, ignites the powder just below it in the tube. This explosion sets off the main charge of explosive. Thus, by connecting a group of caps to a source of electric .current, a number of charges could be exploded simultaneously. This immediately became of great value to mine and quarry operators. Explosives could now be used to break up large masses of material at one time, as against the older, slow method .of blasting small amounts with single charges.The next step was to develop a delay detonator which would allow charges of explosive to fire one after the other, one or two seconds apart. Such detonators allowed first blasts to relieve some rock burden before the next charge fired, giving the second charge an easier task in forcing out more rock, and so on for the rest of the series of charges."

Jan 1, 1953

By M. Mohammadi Zahrani

The morphological modification of primary and eutectic Mg2Si phases by bismuth (Bi) addition in Mg-5wt.% Si in-situ composite was investigated. It was found that with addition of 0.5wt.% Bi, the morphology of primary Mg2Si precipitates was altered from coarse dendritic to polygonal shape, and their mean size was significantly decreased from more than 20 µm to about 8 µm. Moreover, the rod-like eutectic Mg2Si in Bi modified Mg-Si alloy solidified much finer than that of the base alloy. Such improved microstructure of the modified alloy resulted in 10% tensile strength and 20% elongation improvement. The isotropic growth manner of primary Mg2Si particles in modified alloy was attributed to the poisoning of growth in preferred directions by dissolving Bi atoms in Mg2Si lattice. The reduction in size of eutectic Mg2Si was found to be the result of Mg3Bi2 compound formation around eutectic Mg2Si rods.

Oct 1, 2011

By BARRY BANNATYNE

Ombrotrophic Sphagnum peat bogs have a characteristic signature on both colour injrared film (750 nm to 3,000 nm response) and Daedalus injrared line-scanner images (thermal infrared 3 to 5 microns and 8 to 14 microns response). This remote sensing method was used to survey bogs in southeast Manitoba to delineate targets for surface exploration. Target bogs all have a surface growth of Sphagnum; underlying dead Sphagnum ranges from 1 to 6 m thick. Large Sphagnum reserves exist in the Caribou cluster of bogs, and in /979 a bog first identified by infrared sensing was brought into production.

Jan 1, 1984

By W. A. Jankola, M. T. Martin

"The world's first zinc pressure leaching plant at Cominco's Trail operations started production in 1981. Sullivan zinc concentrate is leached at the rate of 190 tpd in a four-compartment autoclave at elevated temperatures and oxygen pressures to produce a zinc sulphate solution and elemental sulphur. Zinc extraction exceeds 98% and sulphide to elemental sulphur conversion exceeds 95%.The sulphur is recovered from the discharged slurry in the underflow of a hydrocyclone, and is upgraded as a flotation concentrate. The concentrate is dewatered, melted and filtered to produce a polished sulphur product of better than 99% purity. An alternative sulphur recovery process employs an unique sulphur separation method that recovers over 90% of the sulphur in the molten state. The remaining sulphur is recovered by flotation following flash discharge of the slurry. The product slurry containing the zinc sulphate solution and the iron-lead residue joins the existing roast-leach zinc plant for purification and zinc electrowinning.IntroductionIn 1981, Cominco Ltd. commissioned the world's first commercial zinc pressure leaching plant at their Trail operations in British Columbia. As part of a $700 million modernization and expansion program for lead and zinc started in 1977, the company installed the first o f two autoclave trains.Prior to pressure leaching, zinc production was closely tied to acid and fertilizer production. Sulphur dioxide produced from roasting the concentrates had to be converted to sulphuric acid. Thus, any expansion of zinc operations with the roast-leach technology would have required extensive modifications to the acid and fertilizer plants as well as to the roasters. Zinc pressure leaching, on the other hand, offered a one-step dissolution of zinc from the concentrates with high extraction, and production of elemental sulphur. The associated dust and sulphur dioxide generated in the roasting process are both eliminated from the working environment of the pressure leach facility. The flexibility allowed by producing elemental sulphur, and the opportunity to break the sulphuric acid link for about 25 per cent of the targeted 272,000 tonnes per year zinc production was very appealing. The process was successfully demonstrated at a pilot plant in 1977(1-6)."

Jan 1, 1985

By Y. Q. Li, X. H. Long

In this work, structural and electronic properties of smithsonite (ZnCO3) and cerussite (PbCO3) as the typical lead-zinc oxide minerals is simulated by means of DFT. The calculated results could be concluded as: (1) The density of states (DOS) of Zn atom in ZnCO3 is nearer to the Fermi level than that of Pb atom in PbCO3, suggesting that the Zn atom of ZnCO3 is more active and easier to interact with water molecules and hydroxyl ions. Smithsonite, therefore, could be more readily depressed in the flotation process. (2) The bond population value of Zn-O (0.23) and C-O (0.92) in ZnCO3 is obviously larger than that of Pb-O (-0.01) and C-O (0.85) in PbCO3, indicating that the covalent characteristic of ZnCO3 is stronger than that of PbCO3. (3) It is shown that the charge of Pb (+1.32e) in PbCO3 is more positive than that of Zn (+1.22e) in ZnCO3, suggesting that cerussite is easier to interacting with HS- compared with smithsonite in the flotation process. In summary, the structural and electronic property of smithsonite is completely different with cerussite, leading to the difference of their flotation behaviour.

Jan 1, 2015