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By A. Boucher, D. Marcotte

"Abstract- The accepted practice for the estimation of thin (2D) vein deposits recommends the use of the grade x thickness service variable (i.e., the accumulation). Grade estimates are obtained indirectly by the estimated accumulation/estimated thickness ratio. This practice stems from the varying support (thickness) problem and the resulting non-additive nature of the grade variable. We compare the actual performance of the direct grade estimation approach used by some practitioners to that of the indirect approach using accumulation. Our simulated and real data indicate that the direct approach is more accurate for point grade estimation where the grade-thickness correlation coefficient is positive (and vice-versa). Moreover, the relative gain of the direct method increases with the (positive) correlation coefficient. This finding contradicts common thinking that the indirect approach should be the preferred method where grade-thickness correlation is strongly positive. Also, for a given positive grade-thickness correlation, the relative gain of the direct method increases with the coefficient of variation of the grade and thickness. Résumé - L’estimation de veines minces (2D) minéralisées est normalement réalisée à l’aide de la variable auxiliaire épaisseur x teneur (i.e., accumulation). Les estimés des teneurs sont alors obtenus indirectement du rapport accumulation estimée/épaisseur estimée. Cette pratique découle du problème du support variable pour la teneur, l’épaisseur de la veine, qui fait que la teneur est alors une variable non-additive. Nous comparons les performances de l’estimation directe de la teneur, utilisée par certains praticiens, à celle de l’approche indirecte. Pour l’estimation ponctuelle des teneurs, nos données simulées et réelles indiquent une meilleure justesse de l’approche directe quand la corrélation teneur-épaisseur est positive (et vice-versa). De plus, le gain relatif de la méthode directe s’accroît avec la valeur de cette corrélation (positive). Ce résultat contredit l’opinion répandue que l’approche indirecte devrait être utilisée en présence de forte corrélation positive de la teneur et de l’épaisseur. Nous montrons également que pour une corrélation positive teneur-épaisseur donnée, le gain de l’approche directe augmente avec les coefficients de variation de l’épaisseur et de la teneur."

Jan 1, 2001

By J. M. Toye

The Canadian nuclear fuel business relates primarily to supplying fuel for Candu reactors. The product development, manufacturing and marketing activities of our nuclear fuel industry will therefore be determined by the rate of growth of the Candu nuclear reactor business. The nature of this relationship between the Canadian nuclear fuel industry and the Canadian Heavy Water Reactor program will be considered, with particular reference to the factors influencing future economic growth.

Jan 1, 1969

By Mohammad Mehdi Salarirad

Fouling of activated carbon by different organic species is a great concern in carbon in pulp and carbon in leach circuits. The rate of gold adsorption onto activated carbon from synthetic gold solutions which contained different amounts of potassium ethyl xanthate (PEX), potassium isobutyl xanthate (PIBX), and methyl isobutyl carbinol (MIBC) were evaluated through batch adsorption tests. The results of these experiments showed that the gold sorption rate rapidly decreases by increasing the concentration of collectors including PIBX and PEX up to 20 mg/L and at higher concentrations, the kinetic rate constant (i.e., k value) gradually leveled off to 53 h-1 for PIBX, which is 46% lower than the 99 h-1 for PEX. At low concentrations of up to 15 mg/L of MIBC, a gradual decrease of the rate constant was observed, while at higher concentrations, the decrease was found to be more pronounced. The gold loading capacity and the rate of gold adsorption onto activated carbon from a gold cyanidation pulp in the presence of flotation reagents were also evaluated. The results of these experiments showed that the flotation reagents have no significant effect on the gold loading capacity of activated carbon at prolong adsorption period, meanwhile the rate of gold adsorption continuously decreases by increasing the concentration of flotation reagents in the leaching solution.

Oct 1, 2011

By K. Oishi

We have developed a 76Cu-3Si-21Zn alloy "ECOBRASS®" containing no lead. When 3% Si is added to a 78Cu-22Zn alloy, kappa and gamma phases participate uniformly in the alpha matrix. When being machined, stress concentrates on these hard phases, namely kappa and gamma, and thereby lowering the required cutting force and yielding segmentalized chips without lubricant. Kappa and gamma phases transform into beta phase under high temperature, which makes it easier to extrude and/or forge the alloy. When 0.08% P and 50 ppm Zr are co-added, the grains of ECOBRASS® castings are refined significantly to become as small as several dozens of micrometers. The grain refinement by the co-addition of P and Zr improves castability, tensile strength and elongation of ECOBRASS® castings. Meanwhile, the lead leachate from an ECOBRASS® water meter, field-tested in pH 6.8 drinking water for one year, was less than 5 ppb without correction. No indication of dezincification corrosion was observed, either. ECOBRASS® is equally suitable for rods, forgings and castings, and makes it possible to produce a complete set of plumbing parts (valves, faucets, etc.) by its own. This way, not only improving recyclability, ECOBRASS® also realizes size and weight reduction due to its good corrosion resistance and high strength.

Jan 1, 2007

By Z. -G. Ren, J. -S. Qian, Y. -G. Yang

The waste slags from chemical and metallurgical plants contain approximately wt 1% water soluble Cr6+. This hexavalent chromium is very harmful to human health, and the treatment of the slags has concerned metallurgists for many years. A sintering method was developed to treat the waste slag. In this process, sinter was made from a mixture of the waste slag containing hexavalent chromium, iron concentrate and coke breezes. During sintering, hexavalent chromium was reduced to trivalent chromium. The latter is known as a non-harmful material and can be used as chromium resource for the production of ferrochromium or chromium-containing cast iron. After sintering the hexavalent chromium in the sinter could be reduced to less than 0.0008%. It was found that the waste slag with fine particles was favourable to the Cr6+ removal. An increase of carbon content in the sintering mixture could increase the rate of Cr6+ removal and the strength of the sinter produced. The rate of Cr6+ removal increased with increasing basicity of the sintering materials with basicity less than B=1.8, above which it decreased with increasing basicity. Blast furnace was found to operate smoothly when using the sinter made from the waste slag containing chromium. However the productivity of sintering machine was slightly low compared to the sintering operation using ordinary raw materials.

Jan 1, 2004

By A. Ingelson, C. Nwapi

"With growing international interest in mineral resources in Central Africa, the importance of transparency in resource development cannot be overemphasized. Without transparency, the region cannot maximize revenues from resources. Although the importance of transparency is beginning to be recognized, many factors can hold back the gains of transparency from resulting in real economic development for the countries involved. This paper reviews current financial, economic, and development literature for Central African countries, with a focus on identifying underlying conditions and specific transactional conditions impacting the effectiveness of transparency in mining development in the region.RÉSUMÉ En raison de l’intérêt international croissant pour les ressources minérales en Afrique centrale, l’importance de la transparence dans le développement des ressources ne peut pas être surestimée. Sans transparence, la région ne peut pas maximiser les revenus tirés de ses ressources. Bien que l’importance de la transparence commence à être reconnue, plusieurs facteurs peuvent freiner les gains acquis de la transparence à produire un véritable développement économique pour les pays touchés. Le présent article analyse la littérature financière, économique et développementale contemporaine pour les pays de l’Afrique centrale, tout en ciblant l’identification des conditions sous-jacentes et les conditions spécifiques transactionnelles qui ont un impact sur l’efficacité de la transparence dans le développement minier de la région."

Jan 1, 2015

By F. Habashi

In the period 1970-1995, a number of hydro metallurgical processes to treat copper concentrates to overcome the pollution problem due to S02 emission in smelters were developed. Pilot and commercial scale plants were built and operated for some time, but eventually all were abandoned a few years later. It is constructive to examine why these processes were abandoned after so much expenditure of funds and effort, so that errors should not be repeated in the future and lessons from the past are learned.

Jan 1, 2007

By M. Uszko

Methane drainage and ventilation methods of methane hazard mitigation are used in the coal mines of Kompania Weglowa S.A. Over 22% of methane released during mining activities is captured by methane drainage systems and transported to the surface. In this article we present development plans for utilization of methane captured and transported to the surface by methane drainage systems. The results of research on the possibility of economic utilization of methane concentrated in ventilation air that leaves the mine through fan diffusers are also described.

Aug 1, 2013

By Andreea Catalina Gluhoi

The oxidation of propylene and methane has been investigated over two series of Au/MOx/Al2O3 and Au/MIOx/MIIOx/Al2O3 catalysts (M, MI, MII =Li, Rb, Mg, Mn, Ce, Zr). Whereas the effect of the presence of MOx or MOI x/MOII x on the oxidation of methane is relatively small, a large enhancement in activity is observed for propylene oxidation. Synergistic effects have been observed by combining ceria or a transition metal oxide (high oxygen storage capacity) with an (earth) alkali metal oxide.

Oct 1, 2003

By R. A. Nemchek

Over the years, concentrator plant design has evolved from a large number of small grinding mills to a small number of large mills. In many cases, all of the tonnage runs through a single mill (typically a large SAG mill), so that the plant’s performance hinges on the productivity of this one machine. Industry specifications attempt to address the critical nature of today’s grinding mills in a manner that is often overly complex, neglects economics, and is not clearly focused on the end user’s goals. This paper surveys current industry practices, and proposes an improved approach to standards writing recognizing that product design, procurement, manufacturing, and quality are all inter-related in contributing to a project’s success. The lessons learned here can be extended to specifications for all types of machinery.

Jan 1, 2012

By M. Bueno

Between 1993 and 2003, a series of AG and SAG mill pilot plant trials were conducted using Hardinge Ical pilot plant scale SAG mills on numerous ore samples and ranging across a wide variety of operating conditions. The data from these tests were used to evaluate the design of SAG and AG mill circuits for over a dozen projects, of which about half were eventually constructed and commissioned. The data were also used in the development of SAG mill modelling, scale-up and simulation procedures by several consultants who had access to part of the data set. Recently, we have had the opportunity to bring this data together and further analyse the consolidated dataset. This paper reports on the outcomes of this analysis that has identified the impacts of different AG/SAG circuit flowsheets and operating conditions on energy efficiency and operating cost.

Jan 1, 2012

By C. Bissue, G. M. Castillo

Newmont’s Phoenix mine started production in March of 2006. Due to the extreme hardness of the ore, the mill has struggled to meet throughput projections. Grinding studies showed that optimizing the existing circuit would not achieve budgeted throughput. These studies also showed that the pebble crusher was being underutilized due to the inability of the SAG mill to break the rock. The concept was developed to supplement the feed to the existing pebble crusher with a secondary crusher. Models of this process looked favorable so a portable crusher was installed to test the process. The temporary crusher was successful at increasing the throughput by 7% and based on the operating data, plans are currently being developed to install a permanent secondary crushing system in front of the SAG mill. This paper will review the results from the test crusher and the flow sheet for the permanent secondary crusher.

Jan 1, 2012

By David Morley

This paper considers the ideal truck-excavator combination, defined as the combination resulting in the lowest direct unit cost, in consideration of multiple haul scenarios characterized by different haul distances, material and equipment availability. Through the application of Monte Carlo simulation, selected for its unique ability to handle the uncertainty of activity durations, the ?four to six passes? loading rule is shown to not correlate with the selection of the minimum cost fleet. Additionally, through the results of the simulation it is determined that the haul truck capacity has a greater effect on the overall efficiency of the system than does the excavator capacity. As a result, in order to arrive at efficient operations, the entire earthmoving system must be viewed as whole, namely, considering haulers together with excavators, as opposed to the popular method of first selecting a loading unit and then selecting a hauler obeying the ?four to six passes? loading rule. Furthermore, truck utilization and excavator utilization exhibit an inverse relationship and neither directly correlates with the overall efficiency of the earthmoving operation. The following conclusions are drawn: first, with limited financial resources, it is more valuable to increase hauling unit size before increasing loading unit size and second, predefined rules or generalizations, not based on evidence, potentially eliminate optimal truck excavator combinations from being considered.

Aug 1, 2013

By E. Marcotte

"Technology developments and improvements are imperative to maintain a viable mineral processing industry. In order to achieve optimum implementation of technology in processing plants, safety conscious and efficient work forces are required. Effective management methods are required to prevent employee injuries, equipment or environmental damage and process losses. Good leadership also provides for employees to perform their work in the safest and most efficient manners to attain optimum recoveries of the valuable minerals and produce high quality mill products. Equipment and processes must be designed, operated and maintained as required to assure safe and efficient mineral processing.INTRODUCTIONThe Canadian mining industry must contend with many challenges to attain and maintain a competitive position in today's global market. Canadian Mineral Processors play a vital role in meeting the challenges and achieving optimum mineral productivity.Ongoing technology developments and improvements continue to be imperative to maintain a viable mineral processing industry. The efficient implementation of technology developments requires a safety conscious, skillful and productive work force.In addition to technical and human resources, challenges may also include governments, labour unions or environmental advocates who at times may appear to be misguided or unrealistic. Canadian Mineral Processors must not allow themselves to be overwhelmed by these apparent obstacles but must use their demonstrated ingenuity to achieve successful solutions.It should be recognized that the majority of the Canadian work force are, in fact, a potentially talented and skillful people with ambitions to excel. As leaders of people, we must provide the methodology, incentive and direction that will allow our work forces to realize their ambitions. If the potentials of our work forces are not recognized and leadership is not properly exercised much loss will occur. That is, safe effective and efficient work will not be achieved."

Jan 1, 1993

By D. MacGREGOR, VERA TUREK

The Badgeley Island quartzite deposir in Georgian Bay is worked by lndusmin Limired and was developed in 1969 to produce a high-qualiry silica for use in rhe ferrosilicon and glass industries. The quartzire is part of the Precambrian Bar River Formarion, and is a generally whire, fine-grained rock containing rhin sericire seams. Primary sedimenrary features wirhin the deposit are bedding and ripple marks. Amphibolite and diabase dykes cur the quarr zire body.

Jan 1, 1984

By Carlos Nieble

Ferteco Mineracao, belonging to the CVRD group, is one of the several iron ore mines in the south east of Brazil. Some of these mines have pit walls of over 350-m height and operations under difficult geo-technical conditions are steadily increasing. In order to mine the 15 million tonnes of high grade hematitic ore remaining in the Fabrica pit, Ferteco had to deal with the following restrictions: Warrant power to its concentrator and pellet plant, relocate the load-out rail road loop, stabilise a poor phillyte slope, relocate a creek on a bench, lower the water table and mine at maximum angles at a slope with phillyte and loose itabirites directly under the rail road loop. Considering these aspects, 3 stages of operations were designed, considering a safe operation, but with the lowest possible security factors at the last mining stage, before the pit would be filled in again with tailings. Stage one above the rail road loop and below the high tension power mast, where the poor phillyte slope was secured by a flexible retaining wall, using old rails and anchors up to 27 meters (80ft) with a working pressure of up till 30 tonnes and stage two with different slope angles, and deep wells, high wall blasting perpendicular to the highwall with relief holes and rerouting the creek in steel half culvert and stage three, the filling in with tailings and recuperation of the deep well pumps. Following studies and analysis were made: Geotechnical and geological studies of all rock formations including rock strength test, a hydrological study to define the lowering of the ground water level, slope stability analysis for every bench and all possible combination of benches, definition of blasting parameters close to the pit slope, a monitoring plan, including topographical movements, vibrations due to blasting, piezometers and pressure cells as well as a plan how to fill up the pit again with tailings in combination with the rising of the ground water level. A close co-operation between the geo-technical consultant, pit operations, the blasting contractor and the geological department resulted in an operation without any incidents, lowering the pit with an additional 3 benches and mining an additional 5 million tonnes of high grade ore.

May 1, 2003

By Xuanxue Mo, Zengqian Hou

"Yidun Island Arc in Sanjiang Region is one of the important Kuroko-type volcanogenic massive sulfide deposits (VMS) districts in southwestern China. Tectonically, the region is situated in the eastern portion of the Tethys orogenic belt, and is a late Triassic extensional island-arc. The island-arc underwent earlier arc construction, intra-arc rifting, later arc construction and backarc spreading during its evolution and formed a complete trench-are-basin system, i.e., the Ganzilitang suture zone, forearc basin, outer are, intra-arc rifting zone, inner arc and back-arc basin from east to west across the island-arc.Kuroko-type VMS deposits and occurrences discovered so far are limited to within the intra-arc rifting zone of the Yidun Island Arc and tend to occur in groups or clusters distributed in separate faultbound basins; e.g., Zengke, Gacun and Xiangcheng basins, in which submarine volcanic rocks, especially bimodal volcanic suites, were extensively developed. The VMS deposits formed in the waning stages of volcanic eruption in the late Triassic and are hosted in the uppermost section of acidic volcanic rocks (rhyolitic-dacitic) within a bimodal suite. The orebodies are associated with these host rocks: rhyolitic-dacitic pyroclastic rocks and exhalites and chemical sedimentary rocks.All VMS deposits in Sanjiang are of the Zn-Pb-Cu type. The architecture of the deposits is twofold, consisting of concordant lenses and layers of massive sulfides and an underlying discordant stockwork. All deposits show metal zoning. The hydrothermal alteration related to mineralization is strong and asymmetrical, and is found dominantly within the stockwork zone and host rocks surrounding the ores. There are two alteration patterns: (1) chloritization - sericitization - silicification from outer sides to core of the alteration pipe; and (2) silicification + sericitization - silicification + carbonate from the lower to upper part of the alteration pipe.The mineralization temperatures of ore-forming fluids vary in the range 200°C to 335°C. Thermal evolution of the fluids displays temperature profiles that first increase and then decrease with progression of mineralization processes. The majority of black-ore minerals (Groups I and informed during intensifying stages of hydrothermal activity, and the majority of semi-yellow-ore minerals (Group III) formed during a thermal maximum. There followed the formation of fine-grained black-ore minerals (Group IV), which interacted with barite layers during decreasing temperature phases.Oxygen and hydrogen isotope studies show that the sources of ore-forming fluids for the Kurokotype VMS deposits are two-fold: seawater and magmatic hydrothermal solutions, represented by the Kuroko deposits in Japan and Kuroko-type VMS deposits in Sanjiang, respectively. In the latter case the hydrothermal solutions reacted with host rocks and mixed with cold seawater percolating downward, and circulated through volcanic rocks resulting in development of alteration zones and formation of ore minerals in Kuroko-type VMS deposits."

Jan 1, 1993

By Philip Peck

Mine closure issues ?Narrow issues: ?Environmental focus; ?Broad issues: ?Social issues and sustainability; ?Continued importance of mining; ?Historical legacies from closed mines; ?Barriers to development; ?Migration [ir]reversibility Dealing with closure issues ?A matter of choice ?Option 1: Engagein solving closure problems as best possible; ?Option 2: Exit, leaving the playing field to firms not interested in solving problems ?Option 3: Delay, till better time to enter or until early entry [by others] fails and pick property up cheap [?].

May 1, 2006

CI, Data and Data Systems Road Analysis Control Quick and simple manual Analysis Case study Visual relation of analysis

May 1, 2013

By X. Z. Yuan

Contamination introduced by the impurities from the feed stream can impact the PEM fuel cell performance dramatically. The presence of these unwanted trace species such as CO, H2S, NH3, can adversely affect the fuel cell functioning. It has been reported that the major impact of CO and H2S contamination on the fuel cell performance is kinetic while the effect of NH3 contamination is speculated as membrane conductivity reduction only. In this paper, a model regarding the NH3 contamination is described and the mechanism of the NH3 contamination is illuminated by the model calculations.

Jan 1, 2005