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The total current inventory of mature fine tailings is estimated to be nearly 850 million m³. Pressure has come to bear on the industry to accelerate its tailings management practices and prevent this inventory from steadily growing. The present paper describes the treatment, management and reclamation of fluid fine tailings. New technologies being evaluated include: i) Thin layered - fines dominated deposits, ii) Deep - fines dominated deposits, iii) Fines enriched sand deposits, and finally iv) water capped disposal in end pit lakes. A brief overview for each of the methods of treatment and disposal for fluid fine tailings is provided.

Aug 1, 2013

By G. Bonin, A. Jamal, G. Preciado, S. Gillis

"Accurate, easy to obtain, and reliable methods of measurement are the cornerstone of shaft and tunnel developments - during their sinking, operation and maintenance, or in some cases, remediation. This paper presents a new methodology to capture existing shaft conditions in such a manner that they can be transferred from the field to a digital copy, where they can be stored and used for engineering design purposes in a space not directly affected by the costs associated with schedule and equipment performance. The methodology utilizes basic principles of excavation alignment (plumb lines and survey instruments) while adding modern LiDAR, geolocation and survey control tools that can more completely capture the surrounding environment. The complete cycle of collection, processing, and delivery of pertinent information underground can take under an hour. During sinking, capturing data as a live stream measurement and being able to assess the alignment of the shaft liner can be critical to meeting rigid design tolerances. As sinking progresses, small changes in alignment or liner deviations can be captured and immediately corrected. Likewise, post-construction as-built conditions can be recorded and digitized, which will allow the mine personnel to compare the proper working condition to the actual condition years later. Observed changes can be identified and planned as future shaft repair works. This methodology has been developed and successfully deployed during the on-going sinking works of the two shafts at the Jansen Potash Project in south-central Saskatchewan and is described in greater detail in this paper.INTRODUCTION Light Detection and Ranging (or LiDAR) scans of the BHP Jansen Production and Service shafts during construction identified sections of both shafts where the internal radius of the temporary primary liner was insufficient to accommodate the tolerances of the permanent liner that was to be installed inside the temporary liner. These locations are referred to as “tights”. The “Tights Removal Program” was designed to collect high resolution point clouds of the shaft, using stringent survey control, that could be compared to the design profile to generate a heat map of locations for removal of up to 75 mm of steel-fiber-reinforced, 70 MPa concrete liner. This work was all on critical path, which made it valuable to save time on the schedule. Because concrete removal was a time-intensive task, it was essential to locate and remove only the concrete that would encroach on the planned permanent liner, while attempting to maximize the amount of cutting time. Removal was carried by a road header attached to a Brokk(R) 160, a small multi-attachment demolition machine."

Jan 1, 2019

By Joerg Hammerschmidt, Marcus Runkel, Steffen Haus

Given the limited number of new plant construction, focus is turning to the optimization of existing metallurgical roasting plants. To meet the goals of high process efficiency with limited capital expenditure, plant owners are looking for new strategies, including digitization and expert support. As a supplier for numerous roasting, gas cleaning and sulfuric acid plants, Outotec has intensified its effort in recent years to develop solutions to accommodate increasing customer need. This article presents a short review on how Outotec is applying advanced control tools for the fluidized bed industry. Focus will be given on how to transfer the existing technology (used in selected Zinc roasting plants for over a year now) to copper roasting. Outotec has developed the Pretium Roaster Optimizer, a system based on heat and mass-balanced simulation models. Direct experience with this technology will be shared and will highlight similarities to the Partial and Sulfate Copper roasting processes. Pretium detects equipment and plant bottlenecks and provides consistency in process development. The Pretium program combines 24/7 advanced online digitalization tools, along with expert personal support when required. INTRODUCTION Fluidized bed reactors have been used for commercial-scale zinc and copper roasting since the 1950s. While the principles of roasting remain unchanged, over time, the technology has advanced to improve process control of roasting plants. In the past, environmental and safety standards were the driving forces for improvement of equipment and plant design. Today, the emphasis is on plant efficiency and optimization. Another change has come in process control philosophy. While plant control and operation have traditionally been the responsibility of owner/operators, they have now shifted to include both integrated digital tools and specific know-how from engineering companies. This can be seen from the earliest design stages through commissioning and into production, as evidenced by zinc roasting plants in Mexico, Brazil and Turkey.

Jan 1, 2019

By Sylvain Castonguay, Sylvain Pilon

"Operator competency is an important factor in the safe and successful operation of today’s complex processes. Competent process unit operators deliver superior performance and results. In greenfield projects, operator competency is particularly critical, as the lack of specific operations experience must be offset with proven practical knowledge and skills to avoid mistakes that can cost millions in terms of start-up delays, production losses and equipment damage. It is, therefore, important to know precisely what competencies are required for a project or site, and what any gaps in operator competency need to be addressed and improved. The success of plant commissioning, start-up and sustainable operations is directly tied to operator competency. The significant investments required for new projects, the exploitation of more challenging ore bodies, and the increasing complexity of plant operations have placed renewed emphasis on the need for competent operators. Furthermore, many large capital projects are being developed in remote regions, often with ties to the delivery of social benefits for the local population in terms of jobs, training and other development opportunities. While automation and processing technologies have helped do more with less, indicators now point to a bottleneck in human performance limiting operational results.Automation industry development in managing abnormal situations, including solutions for simulation and operator training, has produced applications to provide customized and flexible training methods. This paper will discuss tools to automate the operator competency process in order to guide trainers to effectively teach, measure, control, provide feedback, and monitor operator skills. Today’s competency management solutions can be effectively applied throughout the course of an operator’s professional life, as a guide to hiring new operators, for developing competencies to support operations, and also to develop and refine best practices and share lessons learned."

Jan 1, 2016

By Osvaldo A. Bascur

Industrial complexes rely on measurements of flow rates, qualities, and concentrations for monitoring and optimizing their operation. Corporations use the data from the various sensors and measurements to make business decisions, which affect the profitability of the operation. However, gross errors, due to a variety of reasons like faulty sensors, bad instrument calibration, or incorrect process models may corrupt the actionable information supplied to operations, quality managers, and maintenance personnel. The solution is to use the sophisticated new tools to model the process, sift through the available data to locate the gross errors, and use statistical data reconciliation to validate the sensors and instruments. In this way the data are unified to give the most accurate plant information for use by the monitoring and decision making processes. Most mining and metallurgical plants use predictive maintenance policies based on statistical analysis and special techniques, like vibration analysis, and oil and lube analysis for critical equipment. Process control strategies are installed in several metallurgical sites. All of these depend on reliable and accurate data. The data unification methods validate the individual measurements by using the concept of balances and statistical techniques where each instrument is no longer independent of the other measurements in the facility. This paper refers to the data unification and analysis methods required for profitable plant operations. Continuous improvement and monitoring of the measurement system at the plant and analysis of the reconciled data provide the best information for the decision-making process. On-line gross error detection and elimination methods are required to ensure efficient evaluation of process performance and process optimization. An open discussion of the new methods for gross error detection and data unification will be presented.

May 1, 2001

By R. J. McLeod

"A new backfill plant was constructed in 1966 adjacent to the mill of Giant Yellowknife Mines. The reasons for the addition were to increase the storage capacity for sand fill, provide facilities for mixing cement with the fill for mine stope floors and provide a system for pumping fill to B -3 raise, a horizontal distance of 4700 feet from the mill. At the same time it was hoped to increase the density of the fill pumped underground.The plant consists of two only steel storage tanks of approximately 400 tons capacity of sand fill each. They are 17 feet in diameter and have conical bottoms. The cylindrical section is 28 feet high and the conical section 14 feet high. Each tank is fitted with water nozzles around the conical sections to remove solids at the required density. The water pressure on the nozzles is 150 lbs per square inch. The cyclones used to produce the sand back fill are located on top of the storage tanks. Five model Dl0B Kreb cyclones are used for this purpose. The vortex finders are 2 1/ 4 inch and the apex 1 1/4 inch. The cement silo or storage tank is located in the same building. It is a steel tank 17 feet diameter by 41 feet high with a conical bottom. The silo holds 250 tons of bulk cement, which is unloaded by air from a bulk highway carrier using 12 to 15 lbs air pressure. The cement is conveyed to the top of the silo, a distance of 70 feet from the ground by 450 lbs. of air.The mixing tank is a rubber lined steel tank 14 feet in diameter by 14 feet high. It is equipped with a Lightning Mixer supplied by Greey Mixing Equipment Ltd. The mechanism is driven by a 40 HP motor. The lower shaft is unsupported and is equipped with two 36 inch diameter axial flow turbine type rubber covered impellers. The backfill is discharged from the storage tank into the mixing tank by a 5"" x 4"" SRL-C pump powered by a 20 HP motor. A level control in the mixing tank regulates the rate of discharge of this pump through a Grinnell-Saunders automatic control valve. The cement silo is situated at such a height above the mixing tank to allow for a Rota-Lock, a small hopper and a cement feeder. The feeder is an Omega gravimetric belt type dry feeder with a Sensogram controller. The capacity of the cement feeder is 20 tons of cement per hour. The cement and backfill are mixed in the mixing tank at whatever ratio is required for the mine stope floors."

Jan 1, 1968

By Lastram Rolando, Larry J. Hulbert, Louis J. Cabri, J. H. Gille Laflamme, John L. Campbell, Soey H. Sib, Chris G. Ryan

"The mineralogy of samples from the Wellgreen Cu-Ni-Pt-Pd deposit, Yukon Territory, is complex and the metals of interest are contained within fine-grained minerals which vary in size and mineral associations from sample to sample.The major Ni carriers are pentlandite and violarite; the major Cu carrier is chalcopyrite. About 700/0 of the major Ni carriers and 78% of the major Cu qurier will be liberated at a grind of 80% -U,.7 ,an (-500 mesh) for typical low-grade gabbro (West zone, sample No.1). For typical ""clinopyroxenite"" (West zone, sample No.2) and typical ""clinopyroxene-rich peridotite"" (East zone, sample No.3) the liberation would be 71% and 65% for Ni, 74% and 60% for Cu, respectively. Fine grinding, however, cannot liberate the Ni contained in silicates and pyrrhotite, estimated to total 24.5% for typical low-grade gabbro (West zone, sample No. I), 15% for typical ""clinopyroxenite"" (West zone, sample No.2), and 12% for typical ""clinopyroxene-rich peridotite"" (East zone, sample No.3).The principal Pt carrier (sperrylite) varies considerably in grain-size between samples and fine grinding, required to liberate the major Ni and Cu carriers, may be counterproductive in samples where sperrylite is relatively coarse-grained, as some would then be unrecovered (e.g. sample No. 1). In addition, sperrylite in samples No.2 and No.3 is closely associated with magnetite. Palladium occurs in diverse ways. It occurs in the form of several Pd minerals (e.g. sudburyite, testibiopalladite, merenskyite), as a replacement for Ni in several tellurides, antimonides and tellurantimonides (e.g. melonite), or as very low concentrations in pentlandite (up to 34 ppm), chalcopyrite (up to 9 ppm), and pyrrhotite (up to 5.6 ppm). Palladium minerals and Pd-bearing minerals are strongly associated with chalcopyrite in sample No. 1 and will thus report to a Cu concentrate.However, 22% of the total Pd is in solid solution in pentlandite in this sample and will thus report to the Ni concentrate. In samples No.2 and No.3, less Pd occurs in solid solution in pentlandite, and the PGM are distributed mainly among pentlandite, chalcopyrite, and magnetite in sample No. 2, and among pentlandite, pyrrhotite, chalcopyrite, and magnetite in sample No.3. Therefore, the feasibility of magnetic concentration should be investigated for samples like No. 2 and No.3, in order to improve Pt and Pd recoveries. Rhodium was found to occur as rare hollingworthite, in sparse cobaltite (up to 2.7%) and, as low concentrations in chalcopyrite (to 10 ppm) and pentlandite (to 12 ppm) by proton microprobe. Iridium occurs in hollingworthite (up to 7.8%) and very rarely as the native metal or in an undefined Re-Ir-Qs..Ru alloy. Ruthenium was determined by proton microprobe analyses to occur in pentlandite (up to 13 ppm) and chalcopyrite (up to 10 ppm), in addition to rare laurite and Re alloy."

Jan 1, 1993

By N. Maleki

Magnesium matrix composites are widely used in automotive and aerospace industries for achieving higher performance due to their light weight. The Mg2Si intermetallics compound in Mg/Mg2Si composite exhibits many excellent properties such as high melting temperature, high hardness, and low thermal expansion coefficient. However, under normal cast conditions, the primary Mg2Si phase exhibits coarse Chinese script or dendritic morphologies and the eutectic structures is very brittle resulting in the low ductility and strength of the alloys. Modification treatment is a very effective method to obtain fine microstructure and improve the mechanical properties of the alloys due to low production cost. In this investigation various amount of bismuth addition have been carried out on Mg?5wt %Si alloy to refine and modify the morphology of coarse Mg2Si in order to improve the corrosion resistance of the composite product. The effect of Bi content on microstructure of Mg2Si/Mg composite was investigated by optical and scanning electron microscopy followed by EDX analysis and X-Ray diffraction. In order to compare corrosion resistance of unmodified and modified specimens, Immersion test and potentiodynamic polarization (PD) were used. The results showed that by Bi addition, the size of primary phase Mg2Si was considerably reduced and the morphology was modified from a coarse dendritic shape to a polyhedral shape. The results also indicated that the corrosion resistance of Mg?Si alloys was improved by the addition of 1%wt of Bi due to the reduction, refinement and evenly distribution of Mg2Si phase. Indeed, both the morphology and distribution of Mg2Si intermetallic had a great influence on the corrosion behavior of Mg/Mg2Si composite.

Oct 1, 2011

By Richard R. Klimpel, Simon Isherwood

"The industrial processing of ores containing gold and/or platinum minerals is generally mining site specific, e.g. McQuiston and Shoemaker (1985). The variety of various mineral processing techniques employed is extensive and includes size classification, gravity concentration, amalgamation, roasting, cyanidation, chemical leaching, ion ex-change/solvent extraction and froth flotation. Because of the relatively small quantities of Au and Pt that exist in the earth’ s crust, the economical recovery of Pt and Au often requires that the Au and Pt be associated with other industrially important minerals. This association of Au and Pt with other minerals can occur in very complicated mineralogical forms. It is probably safe to say that Au and Pt mineral concentration from natural ores represents some of the most complex metallurgical challenges facing the mining industry.Froth flotation is a technique that is receiving increasing industrial attention for the treatment of finely disseminated and/or associated Au and Pt minerals. The high throughput at relatively low capital cost, the potentially high selectivity, and the existence of a well-established technology for treating more abundant associated minerals such as base metal sulfides makes froth flotation an attractive processing alternative. Broadly speaking, the industrial oriented froth flotation experience with Au and Pt minerals exists in two major categories: 1) the flotation of Au and Pt associated with pyrite (or pyrrhotite) and 2) the flotation of Au and Pt associated with primarily Cu, Zn, or Cu/Pb/Zn containing sulfide ores.In the case of the precious metal association with pyrite (or pyrrhotite), much of the published froth flotation experience comes from South Africa. Typically, such processes are done using an acid side flotation with a collector such as mercaptobenzothiazole. The approach obviously is to float pyrite and hence recover associated gold. Generally the higher the total sulfur recovery the higher the gold recovery. Similar experiences of Pt associated with pyrite are a lot less common mineralogically and hence less well documented industrially. For example, in Canada, Pt is often associated with pyrrhotite but is not really processed as a straight pyrrhotite recovery.For the situation of Au and/or Pt associated with other base metal sulfide minerals, the industrial experience base is quite varied and is well documented from both North and South American operations. The nature of most of these flotation processes is to design, operate, and optimize the installed concentrator to get the Cu, Pb, Zn, Ni, etc. that is the bulk of the valuable sulfide ore and then take whatever precious metal recovery comes. Typically, such flotations are on the basic side using standard thiol collectors such as xanthates, dithiophosphates, thionocarbamates, etc. It is very common with such ores to use mixtures of collectors in order to get ""everything"". Often in such plants, there is an inherent balancing act occuring so as to operate in such a manner to reject pyrite (and pyrrhotite) in order to maintain high base metal mineral concentrate grades and yet recover sufficient precious metals such as Au and Pt minerals which often are associated with the iron sulfides being rejected. Obviously in such an environment, the smelter operation often ends up telling the concentrator what the precious metal recovery actually was in a given production period."

Jan 1, 1994

By Éric Côté

Introduction The 425 Main Ore Zone ? Block of ore partially mined in the late sixties; ? Area was sealed off for over 30 years due to SO2 emissions from oxidizing fill material; 425 Project goal ? Bring the zone back into production without jeopardizing the mine; ? Minimize risks associated to SO2;

Feb 1, 2008

By D. Rylander

The operation of Quarry and Aggregate sites are similar to factory production, since it contains sequential production processes, tasks and activities to produce the output product. Compared to the plant though, the quarry processes are generally not synchronized and controlled towards the overall throughput of the site in real time. Some quarries control parts of the production but do generally not utilize real-time technologies for the whole site and all its activities. This fact indicates a general improvement potential in increased productivity at quarry sites, but also unsolved challenges for the same reason. The main contribution of this paper is the presentation of a Lean based method for how to describe the processes to identify control improvement potential within a site. The aim of the identified improvements is to increase overall site productivity by optimizing site, fleet and machine utilization towards the overall throughput, and minimizing operational expenses and inventories. Further the paper exemplifies the method?s usability with field studies at operational quarry plants successfully identifying and quantifying potential wastes and improvements. In addition the identified productivity improvements based on increased control and automation indicate challenges and needs in wireless communication and sensing technologies.

Aug 1, 2013

By S. H. Logan

The present discussions throughout the civilized world on the subject of gold for monetary purposes may seem due to general economic conditions during the past year. But for some years previously a small group of authorities had warned the world against the continued disregard of an equitable distribution of existing gold reserves, and had urged the necessity of keeping the supply of new gold equal to the monetary demand, which, according to world production and trade figures, increases on the average about 3 per cent per annum. In 1927, Sir John Aird, the President of The Canadian Bank of Commerce, stated that the United States could spare a billion dollars of the supply it then held, 4 ½ billion dollars. About a year and a half ago the Professor of Banking and Currency in the University of London, Mr. T. E. Gregory, said, "If the world finds it impossible to modify its habits so far as to make an organized effort to economize gold seem less Utopian, it must be prepared to pay for its bad habits, in this and other respects, by a possible loss of material welfare." These clear-cut statements were not heeded, perhaps for one reason because most countries were in the flush of prosperity, and making such great demands upon the mining fraternity for industrial materials as to distract attention, at least to some degree, from gold mining. Now the world knows it faces serious problems, first, of making? fully effective its present monetary reserves, which, although badly distributed, are as a whole ample for the needs of the present, and secondly, of preventing a shortage in the supply of new gold, one that may come within the next few years if the present sources of supply are not enlarged, and if there is no marked change in the technique of gold production.

Jan 1, 1931

By M. Imamura

Sumitomo Metal Mining Co., Ltd. has developed a novel hydrometallurgical process for producing not only copper metal but also iron metal from copper concentrates. Because copper concentrates generally contains the same amount of iron as copper, cost-effective rejection of the iron is a key issue for the development of the process. Conventional hydrometallurgical processes produce a large volume of goethite or hematite for disposal and the residues are not environmentally friendly. In the novel Sumitomo hydrometallurgical process, copper is leached effectively from chalcopyrite concentrates using chlorine gas, followed by purification through solvent extraction and electrowinning for copper and iron recovery. This process has many advantages such as the minimization of the volume of solid waste by the recovery of metallic iron and the production of high purity copper. Iron metal with a purity of more than 98% can be recovered from the purified raffinate. This paper presents the results of the batch and continuous tests of the process flowsheet.

Jan 1, 2006

By Ward G. Wilson

Best practice in the design and construction of soil cover systems for mine waste management has advanced extensively over the past two decades. While significant progress has been achieved, we still have little experience with respect to proven performance for cover systems that must last hundreds of years. Some cover designs appear to be functioning well, while at the same time the performance of many more are now being called into question. This presentation evaluates the integrity of cover systems from both a global and local perspective in relation to the uranium industry within Canada.

Aug 1, 2010

By Theophile Yameogo

Much has been said about the methodology of geomechanical design in underground excavations. However, the geological, hydrogeological and geotechnical complexities encountered at the production horizons in the Athabasca Basin commanded for a novel approach in the geomechanical assessment and design of underground openings. Rock mechanics engineers at Cameco McArthur River have been able to establish a practical methodology that goes beyond known conceptual approaches. In this paper, the author describes the original challenges and unique approach in the geomechanical assessment for drifts and chambers development. The example of the successful development of the 510-8225N Chamber will also be presented.

Aug 1, 2010

By Masaru Kato

The plated gold being used by the electronics industry can be broadly classified into two categories: soft gold and hard gold. Soft gold is used for circuit metallization and for bonding semiconductor chips, while hard gold is indispensable as the contact material on electrical connectors, electromechanical relays, and printed circuit boards. The traditional baths from which to plate soft gold as well as hard gold contain the cyanide complex, [Au(CN)2]-, as the source of gold, which liberates free cyanide ions during the plating. The free cyanide is not only highly toxic but also attacks photoresists used to delineate circuit patterns and bonding pads. For these reasons, non-cyanide baths are in use to plate soft gold, whereas hard gold can be plated only from cyanide baths at present. In this presentation, the current status of both electrolytic and electroless non-cyanide processes for plating soft gold will be reviewed.

Oct 1, 2003

By Ian S. Leslie

Seismic monitoring systems for mining operations are being utilized more than ever before in the characterization of rock mass response to underground and open pit mining. This paper provides a review of the use of microseismic monitoring for rock mechanics applications at mines throughout the world. Some practical considerations for the installation of these systems are presented along with techniques for optimizing seismic array coverage. Case studies and installation examples are also provided. Recent applications of advanced seismic analysis techniques are discussed including the determination of event mechanisms, mapping of maximum peak particle velocity (PPV) and seismic hazard fields, and the use of source parameter data for large event re-entry protocol.

Jun 1, 2012

By B. Schulz, T. Leißner, R. G. Merker

"Ores enriched in critical rare earth elements (CREE) keep on being of particular interest. The CREE are Nd, Eu, Tb, Dy, including Y. In conjunction with beneficiation tests on Y-mineral bearing flotation tailings of complicated mineralogy, the Mineral Liberation Analyses (MLA) was used to work out processing characteristics fraction-wise in terms of modal mineralogy, mineral recovery, locking and liberation, and particle size.Size fractions from mechanical sieving (“real fractions”) as well as fractions created virtually by using filters on the MLA-data of the unsieved head material (“virtual fractions”) were investigated comparatively thereby. The ""virtual-sizing-approach"" features a much simpler sample preparation procedure and considerably lower cost if a fraction-wise investigation of a head sample is needed. It can be conveniently applied to intimately locked ores needing a fine grinding to a particle size distribution (PSD) range below 25 microns for instance. However, its practical use is sometimes disputed in terms of the reliability of the results. Results are shown for the main Y-bearing mineral xenotime and selected main gangue minerals of a low grade REE-ore.The influence of sample representativeness, sample preparation and particle counting statistics turned out to be of crucial importance. Given that all preconditions for reliable results are met, locking characteristics, modal mineralogy, and even PSD trends can be read from virtual fractions.The authors encourage processing engineers to use the virtual approach. They propose practical measures to improve the reliability of the MLA results, identify and tackle conflicting results, and mitigate evaluation problems that may arise."

Jan 1, 2016

By S. Esmaeili

The yield strength model developed by Esmaeili, Lloyd and Poole [1] has been adapted to model isothermal aging in Cu-containing AA6xxx alloys, with (a) a moderate and (b) a very low Cu content in the solution-treated, as-quenched, condition, Isothermal calorimetry has been used to analyze the kinetics of precipitation in these alloys, While the kinetic parameters for the low Cu alloy has been derived from the present experiments, the previously determined kinetic parameters for the high Cu alloy AA6111 has been used to model the precipitation kinetics in the moderate Cu alloy. The age hardening responses of both alloys have been well predicted by the model.

Jan 1, 2005

By Y. Kocaefe, D. Bhattacharyay, D. Kocaefe

The carbon anodes used in the electrolytic production of aluminum are made of petroleum coke, recycled anodes and butts, and coal tar pitch. Due to technological advances in the aluminum production technology, aimed at increasing production and decreasing energy consumption and greenhouse gas emissions, better quality anodes are required. Presently, the anode quality is evaluated by visual inspection and the analysis of a small core taken from 1.5-2% of the anodes produced. The visual inspection is susceptible to human error and limited to surface imperfections. The analysis of cores takes time, and therefore, it is difficult to determine the existence of a problem and intervene at the right time. In addition, the core does not represent the whole anode due to the non-homogeneity of anodes. A validated online anode quality control system can highly improve the situation. In this article, an electrical resistivity measurement method developed for this purpose is presented.

Jan 1, 2014