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By Bruce Macdonald

Operational monitoring of slope stability can be achieved by space based InSAR monitoring platforms. Natural and man-made rock slopes are monitored using a novel stack-based InSAR method that exploits both persistent point scatterers (PS) as well as coherent distributed scatterers (DS) such as areas of pavement and sparsely vegetated surfaces. The new method, Homogenous Distributed Scatterer (HDS)-InSAR identifies InSAR targets by using adaptive multilooking of statistically homogenous pixel neighbourhoods combined with thresholding the differential temporal coherence of each target candidate with respect to its surroundings. HDS-InSAR preserves PS and therefore forms a direct generalization to our proven DualScale-PSI method. The density of HDS exceeds that of PS by more than an order of magnitude often providing essentially continuous coverage over urban and industrial landscapes featuring a mix of infrastructure with mostly bare soils or rock surfaces. The improved coverage enables better definition of surface motion and underlying geology, which will lead to superior interpretation of the geophysical mechanisms causing the surface deformation, e.g. through improved integration with 3D deformation modeling. We illustrate the performance of our new HDS-InSAR method compared to DualScale-PSI using displacement results from Vancouver, Canada; Bingham mine, USA; and the Palabora mine, South Africa.

Jun 1, 2012

By Y. Buro

The Bachelor Lake gold deposit occupies an ESE-trending, SW-dipping, silicified shear zone with hematitic alteration. It transects NE-trending, steeply dipping Archean volcanic formations and the O'Brien granite. Major W-SW and N- NE-trending faults have affected the ore zone and the emplacement of the granite intrusions. Movements along the WSW set may have opened the fractures filled by the mineralization. Gold is generally associated with pyrite. Its source, whether a granitic pluton or a volcanic sequence, is undetermined, but the granite probably provided the concentrating mechanisms through heat and hydrothermal solutions.

Jan 1, 1984

By A. Khan

The purpose of this paper is to demonstrate the value of identifying and optimizing throughput constraints by utilizing a Constraint Model. This will be achieved by first understanding the overall concept of Operational Excellence, Continuous Improvement and Theory of Constraints as practiced within Vale Canada Limited. Next, the value of utilizing a Constraint Model is demonstrated by primarily identifying constraints. The applications in utilizing Constraint Models will be demonstrated, including the primary benefit of identifying constraints. The remainder of the paper will focus on how to properly setup a Constraint Model using discrete simulation (regardless of simulation software). Benefits of understanding the severity of constraints and movement of the bottleneck will be recognized. The paper will conclude with the summary of real applications within Vale Canada Limited.

Aug 1, 2013

By John Battista

Uranium mining in Australia has a chequered history. This paper reviews the development of the Australian uranium mining industry from the 1930?s to the present day. It outlines the geology of the various deposits and the mining and metallurgical techniques used to extract the uranium. The industry is profoundly affected by government policies and the paper considers the roles of the Federal, State and local governments. The influence of public opinion on nuclear issues and the effects current and historical policies of various governments have had on uranium mining are outlined. Despite heavy restrictions placed on it, Australia?s uranium mining industry has maintained its place as one of the world?s largest producers. This paper also provides an outline of where the industry in Australia may be headed in future.

Aug 1, 2010

By R. H. Coloquhoun

"INTRODUCTIONDome Mines Limited is located on 3,149 acres in Tisdale, Whitney and Shaw Townships in the City of Timmins in Northern Ontario. The mine and mill facilities are two miles from the town of South Porcupine, now part of greater Timmins.In April of 1909, J.S. Wilson of Massey, Ontario headed a party of prospectors into the Porcupine region. Disembarking from the Temiskaming and Northern Ontario Railway at mileage 222, they established an initial camp on the shore of Frederick House Lake. Following the lake ""break up"" they canoed to their destination, Porcupine Lake, and established a base camp on the west side of the lake by May 23, 1909. At a point approximately two miles from Porcupine Lake the moss on an outcrop was rolled back and gold was discovered.In the spring of 1911, the first mill structure was in the process of being built and consisted of 40 stamp mills, five S'x22' pebble mills and the ancillary equipment for a 300-400 T.P.O. operation. This structure was destroyed along with much of the Porcupine Camp by the famous Porcupine Fire of July 1911. By mid-1912, a steel ""fire proof"" structure was built and utilizing the salvaged mills from the fire, supplemented by the installation of three, 8'x30"" cylindro-conical Hardinge ball mills purchased third hand from Vipond Mines, processed 75,088 tons by year's end.The mill was again levelled by fire in October of 1929, this time caused by an overheated boiler stack. This 11 fire proof"" structure was immediately replaced by a wood structure and again the three Hardinge conical mills and the five 5'x22' pebble mills were restored and utilized. The new mill operated close to its daily capacity of 1500 tons during the last two months of 1930. During the rebuilding phase, the crushing plant was remodelled and a new crusher installed. These plants were protected from fire by a 60,000 gallon water tank and an automatic sprinkler system."

Jan 1, 1984

By A. Dunnett, N. J. Turner, J. Koyanagi, M. Ji

The analysis of rare earth element (REE) samples is a necessary part of the metallurgical process for rare-earth bearing ores, providing invaluable information during testing procedures. This requires a fast, multi-element technique, capable of analyzing a variety of matrices for all rare earth elements. X-ray Fluorescence spectrometry and Instrumental Neutron Activation Analysis are typically used for high concentrations of REE, but they have limitations for some process work applications due to an inability to measure all elements, longer analysis times, significant interferences and elevated detection levels. The work reported here uses new approaches with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to achieve high precision and accuracy within acceptable timeframes. A combination of aerosol dilution and Kinetic Energy Discrimination (KED) produce a process solution assay method that is robust enough to deal with changing sample matrices and concentrations, whilst maintaining low reporting limits and precisions of less than 5% Relative Standard Deviation (RSD). For high concentration metallurgical and geological samples, a sodium peroxide fusion digestion procedure was used, followed by ICP-MS analysis using extended dynamic range (EDR) and KED. Using these technologies, it has been demonstrated that the necessary support can be given to metallurgical process work for REE extraction.

Jan 1, 2014

By J. D. R. Neilsen

The objective of the research conducted and presented herein was to determine the effect of pre-established free gas saturation on the sweep efficiency of an isolated inverted five-spot well pattern. The investigation concluded that the ultimate recovery of an isolated inverted five-spot may be slightly increased by establishing a free gas saturation prior to water flooding; however, of more significance is the extreme deviation of the pattern's performance after water break-through from that commonly obtained from developed well patterns. The rapid "water-out" characteristic common to both linear floods and floods conducted in developed well patterns was not evidenced in the isolated inverted five-spot. Instead, the wells continued to produce oil long after breakthrough until ultimate areal sweep efficiencies of four, five, and six hundred percent were obtained prior to the water-oil ratio becoming excessive.

Jan 1, 1962

By John C. Lyons

"The Wabana iron ore deposits occur as flat-dipping beds of oolitic hematite and chamosite, of Lower Ordovician age, which outcrop for 3 miles along the northwest coast of Bell Island, Conception Bay, Newfound-land, about 16 miles from St. John's.The deposits occur in three zones, Upper, Middle, and Lower beds, separated respectively by 30 feet and 215 feet of shale and sandstone. They are primary sediments laid down in a shallow tidal basin by the precipitating action of a marine environment on iron-rich fresh waters flowing into the basin.The ore-bearing zones, while of wide areal extent, are not uniform beds of hematite that can be mined wholesale. The action of waves and currents during sedimentation; the delta pattern, velocity, and transporting power of streams flowing into the basin; the contours and oscillations of the sea bottom on which the sediments were laid have all been fundamental in the emplacement of richer and thicker mineable sections, and of lean zones so intercalated with shale as to be unmineable.The preservation of the deposits is due to their location in the Conception Bay syncline and to a considerable upthrust of the country east of the bay in post-Ordovician time.The hematite deposits were first recognized as such in 1892, and soon after were acquired by the Nova Scotia Steel and Coal Co. They are now being mined by Dominion Wabana Iron Ore, Limfred, a wholly owned subsidiary of the Dominion Steel and Coal Corporation, Limited. Production started in 1895, and up to the end of 1955 totaled 58,588,516 long tons of hematite ore, having an average dry analysis of about 51 5 per cent iron, 11 8 per cent silica, 0·9 per cent phosphorus, and l ·5 per cent moisture. About 40 per cent of the total tonnage mined has come from surface stripping and on-shore mines. These areas have now been almost completely depleted, and operations are confined to submarine mines extending for two miles off shore under the waters of Conception Bay. Three sub-marine slopes are currently in operation, Nos. 3 and 4 working in the Lower Bed and No. 6 in the Middle Bed. A general picture of the workings is shown in isometric projection in Figure 1. Submarine mining has been entirely by the room-and-pillar method, with an extraction of 60 per cent. The deepest workings, at a vertical depth of 1,850 feet below sea-level, have a rock cover of about 1,500 feet. No mining is done in areas where the rock cover is less than 200 feet. To date mining has explored six square miles of a potential area that may exceed 50 square miles."

Jan 1, 1949

"Beneficiation of low grade ores is the process of increasing the grade of a mineral through unit operations that remove and separate the waste (or gangue) material from the valuable mineral that can then be used for further processing or direct use. Important factors when deciding upon a beneficiation program are the feed grade, mass yield and the metal recovery. As lower grade ores are being processed beneficiation is a critical process. How predictive is laboratory test work for “as built” operating projects? Beneficiation includes all or some of the available unit operations to produce a beneficiation flow sheet i.e. associated unit operations including but not limited to optical sorting, radiometric sorting, crushing and screening, coarse cobbing, jigging, dense media separation (DMS), spirals, magnetic separation, flotation, thickening, filtering and drying. Reference to specific projects and the approach developed in formulating a beneficiation flow sheet and a comparison of difficult and simple beneficiation flow sheets are cited. INTRODUCTIONReserves of high-grade iron ores are reducing all over the world, at an alarming rate, over the years as a result of the rapid increase in demand for steel particularly from Japan and then China. The recovery of mineral value from the low-grade ores using present technology is more expensive than DSO ores due to high energy and capital costs. Beneficiation is defined as a variety of processes whereby extracted ore from mining is reduced to particles that can be separated into mineral and waste.Various physical properties of an ore can be exploited to separate a low grade fraction including variation in hardness, density, reflectance, conductivity and magnetism.""Beneficiation"" of iron ores includes concentration, generally by physical removal of unwanted gangue. Also considered beneficiation is the regulation of product size, or other steps such as agglomeration to improve its chemical or physical characteristics prior to smelting."

Jan 1, 2012

By W. E. Selnes

Introduction In 1938, a survey conducted by the Ontario Mining Association revealed a rather startling fact. Injuries incurred in chute pulling were more numerous than those from any other single cause. This report prompted Mr. W. B. Paton, then Inspector of Mines for Manitoba, to make a similar survey of the mines of his Province. It indicated that, in Manitoba mines, chute accidents ranked second only to those from falls off roofs and sides. Why has the mining industry been so slow to recognize the dangers of chute pulling? A partial answer may be the lack of any systematic classification of accidents according to their real cause. The result has been to attribute to other causes injuries which were a direct outcome of chute pulling, and, indeed, has made it difficult to analyze accidents in the industry as a whole. Perhaps, too, because chutes are generally located in the comparative safety? of the drifts, there has been a tendency to consider the occupation as not very hazardous. Not until enough statistics were obtained on this particular task could it be appraised correctly. The Mining Association's survey has been most helpful, and latterly the industry has done a great deal toward analyzing the causes of chute accidents and toward determining an effective means of overcoming them. Much, however, remains to be done. An effort will be made in this paper to outline methods which have been found successful in materially reducing the number of injuries. Qualifications of the Chute Puller First of all it must be realized that chute-pulling is a specialized occupation. The men require proper training for the job, just as in other mining operations. Care must, therefore, be taken to choose persons whose qualifications fit them for the job. Chute-pulling is an integral part of the general mining operation and cannot be considered as isolated from the tasks of other workers. One of the essential qualifications of a chute-puller is a sufficient knowledge of mining operations to appreciate the effect his work will have on the safety of others in the vicinity. He must take the necessary precautions, by verbal warnings, by placing barricades and signs, or by personally guarding the chutes, to prevent accidents to fellow workers.

Jan 1, 1947

By O. Engler, J. Friis, S. J. Andersen, C. D. Marioara, Y. Aruga

"This work investigates the early stages of precipitation in Al-Mg-Si alloys using a combination of high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), selected area electron diffraction (SAED) and density functional theory (DFT) calculations. Quenching from a high temperature (solution) treatment leaves an alloy in a high-energy unstable state, with solute and vacancies in supersaturation. Thus, already at room temperature (RT) a large driving force exists for solute atoms to cluster and order on the Al matrix positions. DFT calculations indicate that strain alleviation is important at this stage. We observe larger regions of Mg-dominated L10 ordering together with a Si-dominated ordering of smaller clusters in a particular geometry connected to the Si-network found in all the precipitates. In addition, building blocks of the main hardening phase ?'', stabilized by vacancies, are observed at higher, typical pre-aging temperatures.INTRODUCTION Al-Mg-Si (6xxx) alloys are widely used in industry due to a combination of favorable properties such as strength, ductility, corrosion resistance and lightweight. They undergo a complex production route, usually consisting of the following thermo-mechanical steps: casting, homogenization, extrusion or rolling, solution heat treatment (SHT) and artificial aging (AA). The SHT takes place at temperatures above the solvus line in the phase diagram, usually between 500°C and 570°C, followed by a rapid cooling to RT. This ensures that high amounts of solute atoms, uniformly distributed on the cubic face-centered (FCC) Al lattice, together with a large amount of vacancies, are quenched-in. The material is therefore in a super-saturated and unstable state. During the subsequent AA, at temperatures usually between 150°C and 220°C, the solute atoms diffuse and cluster, forming metastable precipitates with needle/ lath/ rod morphologies having the main growth direction along <100>Al. With a maximum alloy solute level (Mg + Si) of only 2%, these precipitates increase material strength up to three times that of pure Al, and are essential for the final material properties. To understand and make better use of this phenomenon, it is imperative to research the nature of the precipitates (such as their atomic structure), measure their key parameters (number density, size, volume fraction) and connect it to material properties (Marioara, Andersen, Zandbergen & Holmestad, 2005; Marioara et al., 2014). The following precipitation sequence is given for the Al-Mg-Si system:"

Jan 1, 2018

By G. R. Cope, C. D. Spence

"The Mac porphyry molybdenum prospect is located 100 km east of Smithers in central British Columbia. The identification of anomalous levels of molybdenum, copper, and silver in three adjacent lakes, sampled during a regional lake sediment survey, lead to the discovery of molybdenite mineralization in float. Subsequent magnetic and soil geochemistry surveys, together with prospecting and mapping, located the source of the float. Mineralization is hosted by a leucocratic granite stock of the Upper Jurassic to Lower Cretaceous Francois Lake Intrusions which has intruded Carboniferous and Permian Cache Creek Group volcanic and sedimentary rocks. The stock measures 500 m by 300m at surface and is mineralized throughout. Sulphide mineralogy is simple and consists of molybdenite with minor pyrite and local chalcopyrite. Molybdenite occurs within fractures and as selvages along quartz stockwork veins and is best developed near the margins of the stock.Known mineralization is coincident with distinct soil geochemistry and magnetic anomalies. Two additional areas of the property display similar features and these remain to be tested.IntroductionThe Mac property is situated in the Babine Lake area of central British Columbia on NTS map sheet 93K/13E, approximately 100 km east of the town of Smithers (Fig. 1). The property lies on the western margin of the Hogem Range at the northern tip of the Nechako Plateau. The centre of the claim block lies at 54°51 ' 30""N and 125 °34 '30""W.Topographically, the claims are characterized by gently rolling hills ranging in elevation from 900 m to 1500 m. Slopes are forested with tall conifers and underbrush is minimal. Flat-lying areas are swampy with tall grasses and scrub brush.Presently, the property is only accessible by helicopter from bases located in Smithers and Fort St. James. Recent road construction by the British Columbia Forest Service has brought road access from Burns Lake to within 5 km due south of the property. It is expected that in the near future, roads will be advanced into the claim area to facilitate logging of mature timber."

Jan 1, 1995

By I. A. Kovalevska

Considered problems: elaboration and implementation of resource-saving technologies, low-cost support systems improvement, openings security and support, based on wallrock condition control with supreme implication into the rock pressure occurrence counteraction work. Results of analytic and underground investigations using computer simulation of the finite elements in order to calculate stressstrain state of the multivariable geomechanical systems are presented. Solutions of concrete objectives are found using spatial geomechanical model of solid motion around openings, considering real geomechanical parameters formation of support forms with proper conditions of their contact and real mechanical characteristics. Ultimate solutions of resource-saving technologies implementation based on the analysis of multivariate vertical, horizontal, and reduced stresses components calculation and also near-contour rock, support bearing components and security constructions movements are found. Results of experimental investigations of combined supports and security constructions, which increase openings&apos; stability in difficult conditions of flat coal seams are presented.

Aug 1, 2013

By C. L. Reichardt

Pressure exerted on gold producers by regulators, project financiers and civil society in the wake of the Baia Mare tailings spill in Romania during 2000 prompted most responsible gold companies to sign up to the International Cyanide Management Code for the Manufacture, Transport and Use of Cyanide in the Production of Gold (the Code). The Code stipulates a ?cradle to grave? approach more comprehensive than that applied to any other mining reagent and poses particular challenges for operators who use cyanide-bearing tailings for backfill. This paper examine some of the challenges for Code compliance facing deep underground gold mines that employ backfill technology, most particularly the requirement to demonstrate that the potential migration of cyanide (and its degradation products) from emplaced backfill will not have an unacceptable impact on worker health and safety or the receiving environment, either during mine life or after closure. Although the Code only contains a single reference to backfill, more careful consideration confirms that most sections of the Code that deal with tailings management are potentially applicable to mines where tailings material is used for backfill, as are certain principles pertaining to aspects of operations, worker safety, emergency response, training and dialogue with stakeholders. For gold mines of the Far West Rand, the most significant cyanide-related risks associated with backfill operations relate to worker exposure to cyanide-bearing seepage and HCN gas. There is potential for seepage of cyanide-bearing water from backfill to compromise the beneficial use of surface and groundwater, and thus impact on downstream users and ecosystems. However, the extreme depth of mining and the specific geological and hydrological controls on the Far West Rand suggest that the potential environmental risks associated with backfill are likely to be considerably less significant than the cyanide-related risks to the workforce.

May 1, 2007

By U. Dillon, G. Blackwell

"Geographic information systems (GIS) provide an efficient means for the recording, manipulation, revision, display and analysis of spatially referenced data. GIS are widely used at the exploration stage of mine development, and are increasingly used for reclamation planning. The ability of a GIS to perform spatial searches and query spatially referenced data make it a powerful tool for use at all stages of mine development. As the amount of data available for analysis increases, so does the power and flexibility of GIS as a planning tool.Starting from the exploration database, this paper describes how a GIS can be used for the development of mining plans based on topography, geology and mineralization information stored in a relational database. Planning decisions approaching the optimal can then be made for a wide range of parameters, including stockpile and waste dump locations, the location of potentially acid generating and neutralizing material for dump design, profitable and risk-controlled mine extraction sequencing, and haul road locations. This is made possible by the overlay and buffer analysis capabilities of a GIS which are explored and exploited to produce a continuous mine production planning program, as well as site remediation and reclamation using a successful case study. The Ore and ProductsThe mines in the Saskatoon area — Agrium, PCS-Cory, PCS-Allan, PCS-Patience Lake, PCS-Lanigan and IMC-Colonsay — extract the ore from the Patience Lake member. The mines in the southeast corner of Saskatchewan — IMC-K1 and K2, PCSRocanville — extract from the Esterhazy member, while IMC-Belle Plaine, near Regina, solution mines potassium chloride from both potash-bearing members.Ore from the Patience Lake member is a medium-grained mixture of sylvite and halite, with a KCl content of 36%, insolubles averaging up to 5.5%, and little or no carnallite.The ore from the Esterhazy member is a coarse-grained mixture of sylvite (KCl) and halite (NaCl) with a small amount of water insolubles, and some carnallite (a K-Mg chloride). Average run-of-mine grades are about 30% KCl."

Jan 1, 2003

By A. K. Debnath

Mining being a site specific activity, land becomes the prime requirement for starting, successful execution and closure of any mining project. Many important mining projects are not progressing satisfactorily just because land is not easily available or environmental/social issues are not addressed properly. This is especially true in the case of open-pit mining, which requires large areas for mining, dumping of waste and additional land for other mine facilities. Mine closure & post mining land use exercises, though funded generously, may not achieve their objectives owing to uneven land profile after mineral extraction is over. One of the prominent solutions to these issues is application of steep angle conveyors in large open pit mines that will result in more space for internal waste dumping and enhanced slope stability of the dump. Additionally, such applications will result in economic extraction of mineral in deep open pits. Land reclamation exercise may start concurrently during early years of mine development as mineral evacuation is limited to a specific part of the mine. Surface mining facilities can also be advanced along with the pit by using modular/portable structures. The paper presented here attempts to address specific land related issues by developing suitable schemes and plans that can be practically implemented in open pit mines using advanced technology i.e. steep angle conveyors.

Aug 1, 2013

The NorthMet deposit of PolyMet Mining is located in northern Minnesota, adjacent to the Iron Range. The deposit is polymetallic with values of Cu, Ni, Co, Zn, Pt, Pd and Au. The processing route selected for extraction of these values utilizes bulk sulfide flotation followed by hydrometallurgical treatment. The hydrometallurgical process has been thoroughly tested on the bench and pilot plant scale at SGS Lakefield Research. The major steps in the process are; ? Chloride-assisted total pressure oxidation for extraction of base and precious metals ?Thickening/filtration/washing of the barren residue from total oxidation ? Reduction and precipitation of Au, Pt, Pd from the oxidation solution ? Partial neutralization of autoclave acid using limestone ? Copper SXlEW for production of copper cathode ? Treatment of a portion of the raffinate from Cu SX to recover NilCo/Zn as either a mixed Ni-Co-Zn hydroxide or as separate Ni hydroxide, Co hydroxide and a Zn sulfate solution. ? Recycling of the remaining raffinate to the autoclave as coolant The process flowsheet, chemistry and bench/pilot plant test results will be reported in this paper.

Jan 1, 2007

By M. Bourassa, R. del Villar, S. St. Arnaud, J. Valenzuela

"Autogenous grinding is used quite frequently for mineral comminution as a result of its lower capital and operating costs. However, it is more difficult to control than conventional grinding, particularly when the autogenous or semiautogenous mill is the only comminution stage (i.e. no secondary grinding is available). Analysis of the control strategy used then becomes extremely important, a task that is greatly simplified by the use of an empirical dynamic simulator:This paper presents the methodology used in the development and the calibration of such a simulator for the autogenous grinding circuit of an iron are concentrator: The various steps are described: industrial data acquisition, preliminary treatment of the gathered information. and empirical modelling of the process. Finally, both the actual and the proposed control strategies are compared using simulation results.This exercise has shown that the variability of some of the controlled variables could be reduced through a better handling of the water addition and the use of filters on some of the signals used for control purposes. The reduction in variability of critical variables, such as power draw, would allow their average value to be increased without the risk of exceeding their safety values. Some advanced control techniques were also tested, with interesting results."

Jan 1, 1995

By Walter Valery, Lauren Hafla, Megan Tibbals, Adrian Dance, Jeff Snyder

"Newmont Mining Corporation’s Carlin (“Carlin”) operation processes roaster feed through a double rotator, dry grinding mill following secondary crushing. Metso Process Technology & Innovation (“PTI”) was involved in a review of crushing and dry grinding circuit operations in August 2009. A number of opportunities for increased throughput were identified in the PTI study.Extended plant trials were conducted in July 2010 to provide justification for possible circuit modifications and if needed, additional equipment. The trials confirmed that a finer crusher product would reduce the build-up of material ahead of the coarse grinding chamber in the double-rotator. Also revealed were material transport and airflow restrictions in the dry grinding circuit that resulted in a high circulating load.The secondary crushing plant demonstrated it was capable of reducing the amount of +¾” material in the mill feed thus increasing dry grinding throughput. However, wet and sticky feed affected screening efficiency resulting in low utilisation of the existing crusher capacity. The open circuit configuration also made it difficult to control crushing circuit product size.For the dry grinding circuit, changes in grinding media size, transfer grate design and increased airflow were recommended to reduce circulating load issues and increase circuit capacity. This paper summarises the crushing and grinding circuit review, the extended site trials performed by PTI and the improvements in dry grinding operation that resulted from this study."

Jan 1, 2012

By S. Timbillah, R. LaDouceur, C. A. Young

A low carbon-chain trithiocarbonate ((NaOOC)CH2SCSSNa), known as Orfom® D8, was tested as an organic depressant in the differential flotation separation of chalcopyrite and molybdenite in the presence of sodium isopropyl xanthate (SIPX) or potassium ethyl xanthate (KEX). Flotation studies show that Orfom® D8 depressed chalcopyrite while molybdenite remained floatable. A study of the mechanism of adsorption indicated that Orfom® D8 adsorbs on chalcopyrite through its trithiol (CS -) functional group via both chemisorption and Orfom® D8-metal complexation. The Orfom® D8 depressant is selective and does not form any Orfom® D8-molybdenite bonds. Thus, the combination of the depressant in the presence of either collectors depressed the chalcopyrite and floated the molybdenite. Fundamental parameters of the Orfom® D8 including pKa determination as well as possible decomposition products of the depressant are reported. This study includes an economic case illustrating why using Orfom® D8 can be beneficial. INTRODUCTION Depressants are incorporated in mineral flotation units in the minerals processing industry to make or keep certain minerals selectively hydrophilic. Most reagents used are inorganic and include, for instance, sodium hydrosulphide (NaHS) which is the major reagent used for depressing sulphide minerals, particularly those containing copper, iron and lead. However, the issues with its use include high toxicity, tendency to explode, strong odour, and high consumption due to required high dosages as well as its tendency to oxidise in air. The latter can be overcome by conducting flotation in inert atmosphere such as nitrogen and recycling of the flotation process water. The use of more novel depressants that are essentially organic including homopolar reagents with hydrophilic functional groups on both ends of its structure adsorb onto a target mineral surface with one polar end, the other polar end orients into the bulk solution making the surface hydrophilic and thus, ensuring that the desired mineral does not float. The stringent environmental and safety regulations being implemented in recent times mean that the search for more environmentally friendly chemical reagents is a must have. The use of organic depressants for flotation systems such as Cu-Mo sulfide bulk concentrates has become increasingly important because of the health, safety and environmental issues surrounding the use of inorganic depressants. Nagaraj et al. (1983) investigated the Cu-Mo sulphide flotation system using a structure-activity study of depressants. They found that a major advantage of organic depressants is the ability to tailor-make organic molecules to suit many requirements and thus, eliminate the guess work approach that was predominant in the industry.

Jan 1, 2019