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By K. Adham, T. Buchholz

"Significant capacity increases to meet new production demands can often be fulfilled through debottlenecking of an existing production facility, rather than the more expensive option of building new plants and facing new environmental and infrastructure challenges. To achieve that goal, it is important to model and calculate the existing ultimate capacity of each processing plant area, and that of each key equipment sector within the plant areas. This paper describes a methodology of how process modeling tools can be used to simulate the processing steps, how to estimate their existing and ultimate capacities, and how to determine the sweet-spots (minimum cost points) for a plant expansion – leading to a road map of the subsequent debottlenecking project implementation.The debottlenecking technique is presented through a generic work-flow narrative which can be applied to different mineral processing studies, starting with establishment of heat-and-mass balances, drawing a bottleneck diagram, brainstorming capacity increase options, and preparing a cost-capacity curve. Hatch has successfully applied this technique to a number of plant capacity studies, with great benefits to our industrial clients.INTRODUCTIONWith the softening of the metals and minerals prices, and the escalated costs of building new processing plants, it is now economically more viable to improve and debottleneck the existing facilities, rather than build new ones. However, spending new money on old plants requires careful considerations, in order to identify the most economically advantageous incremental steps of improvement and the best potential returns on investment. Process modeling, hand in hand with plant measurements, can identify the best scenarios to balance the three aspects of plant capacity (nameplate, utilization and yield), both at the global and the individual system and subsystem levels."

Jan 1, 2016

By N. Kolev, M. Poibrenski, I. Nishkov

"The following paper examines the flotation of copper porphyry ores in Assarel concentrator with focus on the reasons for low molybdenum recovery in the final copper concentrate. The copper-porphyry ore of the Assarel deposit is characterized by its variable mineral composition and high clay content, which influence the process efficiency of their concentration. Particle size distribution, chemical and mineralogical analyses have been made on various flotation products showing the distribution of the main elements of interest - copper and molybdenum. It was found that molybdenum is not concentrated into the final copper concentrate as usual in the flotation of copper-molybdenum ores but into the tailings of the copper selective flotation (cleaner tailings). An attempt to explain these results has been made with proposals to improve molybdenum flotation. Low floatability of molybdenite is caused by the ultrafine clay minerals content in both the run-of-mine ore and copper flotation streams. In order to achieve selectivity of copper minerals against pyrite a significant amount of lime is used in the plant leading to higher pH conditions, which could be another possible explanation for the molybdenite depression. The results obtained after the laboratory experiments, showed that it is possible to restore molybdenite floatability using traditional reagents such as diesel, kerosene, etc., and introducing a new polymeric reagent as froth modifier.INTRODUCTIONOne of the main technical difficulties in the area of copper-molybdenum flotation is the selective recovery of both metals, especially the fine (<40 micron) mineral particles. The problem is even more serious when Cu-Mo ore treated contains a lot of natural fine particles, predominantly clays, micas and other gangue minerals. Peng and Zhao (2011) conclude that the mineral processing industry is well aware of the difficulty in treating ores in the presence of clay minerals. Tremolada et al (2010) found that clay minerals have been named as the main problem in ore beneficiation processes due to their small size, which cause a higher viscosity in grinding. In flotation, these clay minerals have natural hydrophobicity or float by entrainment.The impact of clay mineralogy on flotation performance has been reviewed in the literature and the various deleterious roles of clay minerals have been investigated (Bulatovic, Wyslouzil & Kant 1999; Jorjani et al, 2011; Farrokhpay, Bradshaw & Dunn, 2013). It is widely accepted that the actual flotation recovery problem appears to be caused by the properties of these fine particles: small mass (and/or momentum) – high interfacial free energy (Rubio et al., 2007; Farrokhpay, 2011). In most cases, the loss in recovery is found to be insignificant, but the detrimental effect on the concentrate grade is found to be more prominent. The main reasons for the flotation inefficiency are the low probability of bubble-particle collision and adhesion, formation of dense froths and as a result - low process kinetics. A great deal of fine valuable minerals is discarded as slime in flotation due to lack of effective recovery methods."

Jan 1, 2016

By Marke Wong

? Vietnam?s economy is growing so fast that gross domestic product (GDP) growth remained above 8% in 2005 and exports are rising steadily at 25% per year. ? Demand for electricity is expected to increase 18% per year through 2010 requiring an additional estimated 7,547 MW before 2010 ? Domestic coal demand is expected to be over 45 Mt by 2010. ? The Quang Ninhcoal deposits are estimated at 6.5-7 billion tons (350m) Vietnam News Agency. Saturday, May, 6, 2006. ? National resources are now estimated at 10 billion tonnes; not including a relative new coal bed discovery estimated at 210 billion tonnesin the Red River Basin.

May 1, 2006

The quality of refractory bricks and castables could be determined by direct measurements of their material properties such as elastic properties, porosity, density, etc. using conventional static or non-destructive testing (NDT) dynamic techniques. Quality monitoring of refractory linings is much more challenging and complicated. The static methods require undesirable drilling and sample extractions from the furnace structure. A more desirable alternative is the use of NDT techniques for material quality estimation. The Acousto Ultrasonic-Echo (AU-E) technique is a new stress wave propagation approach for monitoring the quality of refractory linings in operating furnaces. In this paper, the conceptual methodology for the AU-E technique is described, the capabilities and limitations are expanded, and the results from two case studies are discussed.

Jan 1, 2005

By E. M. De Souza, P. Lausch, D. O. DeGagné, J. F. Archibald

"The potential use of industrial and municipal waste glass as a partial pozzolanic replacement for Normal Portland cement in mine backfill has been investigated. Considerable quantities of glass are currently discarded into landfill sites at high cost to municipal and industrial users with no foreseeable environmental benefits being gained by such disposal. This research study was undertaken to assess the viability of using ground waste glass materials as partial binder replacement of Portland cement fractionswithin consolidated mine backfill materials. The program was implemented to review various factors that could influence successful incorporation of glass waste replacement of cement, these factors being the feasibility of glass waste procurement, determination of process economics and the physical and chemical suitability of ground waste glass materials to generate adequate backfill strength when replacing Normal Portland cement fractions. A series of laboratory assessment trials were established to evaluate backfill component characteristics and mixture strength properties for both standard Portland cement-consolidated and blended Portland cement/ground waste glass-consolidated backfill materials. Side-by-side review of the strength behaviour of various component backfill/cement mixtures was designed to permit comparative evaluation of the capabilities of ground waste glass and Portland cement products as backfill consolidating agents"

Jan 1, 1995

By Robert B. Parsons

"One of the disadvantages of the federal government&apos;s idea of ""taxation by consultation"" is that it seems to take longer to enact new legislation. The proposed new rules for taxing automobile benefits is one example. Here is a ball which has been batted around between government and the public several times and still has not come down to earth. Fasten your seatbelts, there may be more to come. IntroductionThe draft legislation released on April 13 contains the details of the government&apos;s current proposals on car expenses and benefits. They differ significantly from the last announced position. Finance Minister Wilson has indicated that the release in draft form will provide an opportunity for the Commons Standing Committee on Finance and Economic Affairs (the Blenkarn committee) and other interested persons to comment before the legislation is introduced in Parliament. Accordingly, there may yet be revisions.Notwithstanding the prospect of further changes, the proposed rules generally come into force in 1988. While taxpayers may welcome some of these changes, particularly the increase in the tax-exempt allowance, many must be frustrated that, at this late date, the rules for the current taxation year are not yet finalized."

Jan 1, 1988

By Didier Fohlen

Three Policy Shifts to enhance IFC?s Accountability ? Comprehensive and dynamic treatment of social, health, safety and environmental risks ?Covers a range of risks encountered by clients in emerging markets ?Framework to anticipate risks and to address them as they arise ?Includes community development, biodiversity, human rights ... ? Effective principles to guide an outcomes-based approach ?By clients and IFC ?Focus on broad community support and value-added sustainable development initiatives Enhanced governance, transparency and disclosure

May 1, 2006

By A. C. Ter-Oganesyants, N. N. Anisimova, G. P. Kotukhova, G. N. Dylko

The process utilized at Norilsk Nickel Polar Circle Division for treating slimes from the electrorefining of copper and nickel was developed in the late nineteen fifties and has survived without any fundamental changes. This technology is a combination of pyro and hydrometallurgical operations to produce PGM concentrates that are sent away for refining. The characteristic feature of the current technology is multiple-stage, extended cycle treatment with significant incomplete production, low labour and automation efficiency and poor hygiene and sanitary conditions. To eliminate all negative aspects mentioned above, specialists of Norilsk Nickel Polar Circle Division have developed a new hydrometallurgical process for treating electrolytic slimes. The main steps of the flow sheet developed are autoclave leaching of the slimes and electrochemical opening-up of a cake from autoclave leaching. The implementation of the new process will allow Norilsk Nickel Polar Circle Division to shorten the process cycle 4-5-fold thus reducing the volume of incomplete production, considerably increase labour efficiency, simultaneously improving working conditions, upgrade the final concentrate, reducing costs and increasing PGM recovery during refining and, ensure higher security of precious metals by employing automated processes and vacuum sealed units.

Jan 1, 2004

By J. B. Rubenstein

This work demonstrates the feasibility of using confocal surface profilometry to measure and characterize wear of graphite anode surfaces. This method was tested using anode samples that were electrolyzed for 24 hours in a laboratory-scale magnesium cell with a high oxide molten salt electrolyte. The oxide produced accelerated wear on anodes designed for low oxide electrolytes. Contour maps, which are effective at displaying non-uniform wear, and total graphite consumption values were generated from the collected surface coordinates. Along with both qualitative and quantitative analysis capabilities, this measurement system was shown to have a fine resolution and a low detection limit.

Jan 1, 2004

By K. V. Konigsmann

"Concentrate dewatering operations have a significant influence on the economics of base metal beneficiation. The expenditures f or energy and labour per tonne of product are high. The relatively low efficiencies of standard techniques present inducements for process modifications. Development efforts at several Noranda concentrators led to process changes which improved productivity, namely, agitated pulp storage in large vessels, process automation and pressure filtration.IntroductionA program was initiated in 1968 with the aim of improving utilization of manpower and equipment in dewatering operations. The following considerations motivated us in this effort: Firstly, filters and dryers had traditionally been operated continuously and in step with grinding and flotation circuits. The demand for labour and equipment operating time was fixed and was not determined by the rate of concentrate production.Secondly, dewatering equipment had usually been designed to handle the concentrate tonnages which were produced when mill feed grades were high; therefore the equipment operated at less than capacity when treating ores of average metal content. The first goal was the separation of the flotation process from concentrate dewatering by development of a practical storage system for concentrate pulps . A second objective was the gradual introduction of dependable automatic controls. The steep increase in energy costs after 1973 added urgency to the search for dewatering processes which were highly energy efficient."

Jan 1, 1984

By Angeles Mendoza Sammet

Based on the analysis of issues associated to conflicts between communities and mining companies in Mexico, this paper suggests actions to make mining more sustainable in Mexico. Interviews with key informants and a revision of documental information available on the internet provided information on 15 cases of conflicts in various parts of the country. The issues varied from incompliance with environmental law to assassination of community members opposing mining. The analysis concludes that mining is not sustainable in Mexico. Both mining companies and the Government of Mexico can make changes to improve sustainability. Mining companies could take a proactive approach and engage in consultation with communities before starting operations. Sharing information with communities on environmental management programs and monitoring results can be a way to start building trust and demonstrate environmental commitments. Companies can implement and evaluate CSR policies to ensure that all staff and contractors are trained on them to reduce and/or prevent corruption and violations of human and indigenous rights. Only 3 of the 15 companies had clear social responsibility policies or sustainability targets, but no reports evaluating them. Complying with the law does not make a project sustainable because of corruption, deficient enforcement, and gaps in legislation. The Government of Mexico should address the following points to make mining more consistent with sustainable development. Update the mining legislation to introduce sustainable development principles and consultation. Incorporate the notion of Free, Prior, Informed Consent (FPIC) for Indigenous People (IP) on all applicable Mexican laws or regulations. The government should not grant concessions on protected areas or indigenous lands without extensive meaningful consultation with the public, IP and land owners. Finally, it is vital to increase SEMARNAT?s capacity to review impact assessment reports and inspect and monitor environmental compliance along the life cycle of projects.

Aug 1, 2013

By Phil Molloy

"In March, 1968, Skega Ruh her Liners were used to reline the shell of an 8' x 12' Allis Chalmers ball mill.This mill is used to regrind the cyanided pulp from 58i -200 mesh to 92% -200 mesh prior to this pulp passing to the flotation circuit, at approximately 450 tons per day.Before the use of rubber liners, the regrind ball Mill shell had been lined with single wave ni-hard liner!'. These liners had an average life of five years. Ni-hard end liners were used both prior to and during the use of rubber liners, as the life of the ni-hard end liners was about seven years, and it was thus felt that little economic benefit would be realized by lining the ball mill ends with rubber.The rubber lining used has a thickness of 57.15 millimeters and the square shaped lifter bars which are spaced at 14~ inch centres, have a 4"" x 4"" cross-sectional dimension.With the use of ni-hard liners, the consumption of 1 1/4 forged steel balls averaged 1.062 pounds per ton, Using rubber liners the consumption of l~"" forged steel balls increased to 1.368 pounds per ton. Also the level of the ball load which previously had been kept at approximately 18 inches below the mill discharge, had to be increased to approximately 8 inches below the mill discharge in order to effect the same grind.The initial gri4ding performance of the newly relined mill was also poor, until the leading edge of the rubber lifter bars, which were square shaped in cross-section had been worn to a rounded profile. These lifter bars were replaced after 4 years and 3 months of operation.The advantages of rubber liners in our opinion is as follows:"

Jan 1, 1974

By J. H. Archibald

"This paper describes the use of vector analysis for determining the intersection of mineral deposit veins. The mathematical evolution of the analysis is outlined.IntroductionMany mineral deposits can be characterized by sets of intersecting veins. Often a vein will have a steep dip and may intersect with another similar vein. Finding the intersections of these veins is usually done by graphical means. Structural geologists, by the methods of descriptive geometry, can usual ly predict where intersections of veins will occur. This method normally requires accurate drafting and layout of the problem and does not always lend itself to solution in the field.Another method for solving this problem involves the use of vector analysis, which is easily adapted to hand-held programmable calculators. It is assumed at the outset that the reader is familiar with the dot and cross products used in vector analysis. Two excellent references are cited at the end of this note for convenience.A plane, in general, is defined by three points. The points of interest here are the points where three vertical drillholes penetrate the vein, or plane, in question. The elevations of these three points are best referred to sea level. This requires knowing the elevation of the collar of the drillhole above sea level and the drillhole depth from the collar to the vein. The elevation of the intersection point is then found by subtracting the hole depth from the collar elevation. These three points now define the plane of the vein. A similar set of three points will define a second vein, and it is our object to show analytically their intersection if it exists."

Jan 1, 1983

By B. B. Adhikari, S. Alam, Ohto Kawakita, Abe Pangeni

Effective recovery of gold was investigated by using adsorption gels prepared from pure cellulose, cotton and paper by treating with concentrated sulfuric acid. Only gold was adsorbed with extraordinary high loading capacity from varying concentrations of hydrochloric acid separated from other precious metals and base metals. The formation of fine powders of metallic gold was visually observed, which is attributable to the selective reduction of gold (III) ion to metallic gold clue to its high oxidation-reduction potential. Recovery of gold from the leach liquor of hydrochloric acid of circuit boards from spent mobile phones was attempted using pure cellulose gel.

Jan 1, 2011

By Jerry Z. Lu

Belt conveyor design involves the evaluation of belt tensions, drive selection, pulley configuration and other technical issues. The conveyor belt tensions vary with conveyor layout, drive pulley configuration, belt selection, and idler selection. The decisions for the belt conveyor construction always take all technical, commercial and maintenance issues into consideration. A good conveyor design shall provide required operational features and at the same time be cost effective. The common issues for an engineer to face during belt conveyor design include: (1) Conveyor drive selection ? drive with fluid couplings or variable frequency drives; (2) Drive system configurations - single pulley large drives or dual pulley smaller drives, if intermediate tripper booster drives shall be applied, what power ratio should be adopted for a multi-drive conveyor; (3) Gear reducers ? shaft mount drives, right angle gear reducers or parallel gear reducers; (4) Drive pulley lagging - ceramic lagging or rubber lagging; If ceramic lagging, what type should be used. (5) Conveyor speed variation ? If conveyors run at variable speeds, faster speed/lower percentage loading or slower speed/higher percentage loading. In many cases the decision maker find themselves in a dilemma ? technical benefits vs. financial benefits, capital cost vs. operational cost, and capital and operational cost vs. maintenance effort. Although many conveyor design topics above have been discussed in numerous technical papers and design reference books, management executives and inexperienced engineers may be confused and feel lost. The consultation of people around them may lead to different opinions since experiences tend to vary, making the decision making process complicated. The purpose of this paper is to simplify these complicated issues and provide useful guidelines for belt conveyor design. This paper focuses more on providing simple and practical answers and solutions instead of discussing each topic academically and theoretically in depth.

Nov 1, 2011

By Jonathan Peck, Jim Gray

"With the implementation of more advanced monitoring, control and locating systems in surface mines, there is an ever increasing need for their mine-wide integration toward achieving over-all optimization. AQUILA Mining Systems Ltd. is developing the basis for a comprehensive real-time monitoring, control and information system called the Total Mining System or TMS. This system is being designed to address both current and future needs of open pit mines toward improving productivity and minimizing costs, through better two-way information flow between each component in the operation. At a basic level, feedback from equipment and process monitoring will enable decision making to be based on quantitative, on-demand information, thus permitting proactive rather than reactive planning. Dynamic planning would be a valuable tool as market conditions fluctuate, equipment fleets age and variations in the grade, quality, geometry and hardness of the mined material all contribute to either changing production targets or levels of achievable performance. Such a capability could be implemented within the next two years.At a higher level, and within five years, autonomous operation and/or real-time supervisory control of mobile and stationary equipment in open pit mines will be achieved. A discussion is provided in regard to the development and implementation of an autonomous haultruck and blasthole drill, to demonstrate the need for such a system.This paper outlines a preliminary program for the design, development and implementation of this system, primarily in relation to high-level communications and its role in the future automation of open pit mobile equipment."

Jan 1, 1995

By S. Papanakli, Th. Rondoyanni, N. Sabatakakis, K. Kavoura, G. Tsiambaos

"A representative composite fault-related landslide of the Corinth Gulf graben named “Panagopoula” is reported that considered to be one of the most prone to slope instability sites along the main motorway and railway connecting Athens with the city of Patras. The presence of tectonically highly sheared and weathered geological formations, including Alpine basement (mainly flysch) contributes to the site instability, triggered/reactivated by seismic activity and heavy rainfalls. Although a series of remedial measures have been already constructed, the inclinometer readings during the last twenty years time period show a continuous very slow movement which indicates that the landslide is still ""active"". This fact has resulted to divert the axes of the new motorway and railway through twin tunnels which are under construction. INTRODUCTIONThe spatial and temporal evolution of landslides in the case of structurally complex slopes is lithologically and often structurally controlled while their type and frequency are mainly related to tectonic and lithological anisotropy (Baron et al. 2005; Hradecky et al. 2007). The triggering mechanisms mainly include: (a) excessive rainfall generating high pore pressure and (b) strong earthquakes resulting in dynamic loading conditions at the failure surface. Data such as past earthquakes or the precipitation records are useful to be gathered when a landslide model is examined since they could act as a landslide triggering mechanism. Recording of the movement through surface and inclinometer measurements as well as combination of the above information with historical records of failure could lead to a more accurate estimation of the location of the failure surface and understanding of the landslide mechanism.Slope instability in the southern segment of the Gulf of Corinth, Northern Peloponnesus, Greece, is ubiquitous and ranges from deep-seated bedrock failure to secondary earth flows in recent deposits. In this part of Greece, the periodically induced landslide events triggered by heavy rainfall, earthquake and anthropogenic activity are closely related to active fault tectonics. The Gulf of Corinth is considered as a typical example of a relatively simple asymmetric half-graben with major border faults to the south and a flexure of the northern shore. Panagopoula landslide is located along the trace of a WNW trending normal fault (dipping northwards) (Figure 1). The area is considered to be one of those most prone to slope instability along the E95 motorway and railway connecting Athens with the city of Patras."

Jan 1, 2015

By Denilson Coutinho, Euler Soares, Paulo de Tarso, Jordana Ferreira, John R. Goode, Andreas Sprecher, Alexandre Rocha

The Serra Verde Project is located in the northern part of Goiás state, Brazil, and comprises 49 mineral claims covering an area of 69,814 ha. The Serra Verde deposit is a rare earth element (REE) enriched weathered granite comparable to the weathered granite, or ionic-clay, deposits found in southeastern China. The Mineral Reserves of the Serra Verde Project total 388 Mt (Measured and Indicated) at an average grade of 1,484 ppm of REE oxide (REO). Several hundred agitated leach and column leach tests have confirmed recovery of about 40 to 55% of the REE, except for Ce, using simple desorption techniques. Present plans call for a heap leach operation followed by precipitation of impurities and precipitation of a pure REE carbonate suitable for refining and separation. The project plan includes initial production of 5,000 t/a of REO, with a high content of heavy and critical REO, rising to 10,000 t/a of REO. This production rate will be obtained by mining of the Mineral Reserves over a 22-year mine life at an initial rate of 6 Mt/a for the first four years with the mining rate thereafter increasing as required by grade and production targets.

Jan 1, 2014

By W. L. Uglow

In recent years, the microscope has come to be recognized as a valuable aid to engineers whose business is the discovery, development, concentration or reduction of metallic ores. In many of the large treatment plants microscopical research has already an important status; and in the hands of efficient operators the microscope has indicated methods of solving ore problems resulting in the saving of thousands of dollars that otherwise might have been lost in tailings, or expended in freight rates or smelter charges. Failure to procure all the information that the microscope can supply concerning the physical and mineralogical characteristics of complex ores has in many cases led to the construction of unsuitable concentrators, just as the failure to investigate in detail the geological conditions of an ore deposit has often results in the squandering of money on shaft sinking, and mechanical installations which subsequent development of the deposit failed to justify. The great progress recently made in the selective separation of minerals by means of the various processes of flotation and leaching brings strongly to our attention, the scope of the field in which microscopical methods may be advantageously employed. The microscope enables one to observe the minute details of rock, ore, gangue, concentrate, tailing, matte, slag and metal, that are invisible to the naked eye. Furthermore, the technique of microscopal research has been so highly developed that a microscopist can not only observe, but deter-mine the compositions and measure the diameters of the mineral constituents in the ore to be treated. Magnifications of these constituents up to 3,000 diameters may be produced by the proper combination of eyepiece, objective, and projection apparatus, and the images thus viewed may be photographed through the microscope, and permanent records made of them.

Jan 1, 1924

By Brian Hart, Stamen Dimov, Aparup Chattopadhyay, Barun K. Gorain

"A novel gold deportment technique has been developed for complex copper-gold and double refractory gold ores using state-of-the-art technology. Characterization of these ores is a challenging task due to low copper and gold grades in ores, presence of both primary and secondary copper sulfide phases and variable proportion of visible and invisible gold in different sulfides and iron oxide phases.Double refractory ores are mainly composed of silicates and carbonates with moderate clay and mica, and minor amounts of sulfides and organic carbonaceous matter. Gold mostly occurs as ""invisible gold"" (sub-microscopic gold) as solid solution or as colloidal-sized particles in different sulfides and other phases. The dominance of invisible gold and presence of highly preg-robbing and finely disseminated carbonaceous matter adversely affects gold recovery in flotation and leach circuits. Characterization of this carbonaceous matter, commonly known as TCM and quantification of gold associated within TCM, along with different sulfide and oxide phases is highly complex and challenging.Studies were initiated on various complex ore deposits and also on samples representing various process streams. This paper presents the development of a systematic approach to diagnostic metallurgy using state-of-the-art optical and automated mineralogy techniques, namely, micro-probe, dynamic SIMS and TOF-SIMS analysis for quantification of invisible and visible precious metal content in various species. The relevance of the mineralogy characterization to metallurgy will also be discussed in this paper."

Jan 1, 2016