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By Brian Hart, Stamen S. Dimov

"The naturally occurring carbonaceous material (CM) in gold bearing ores often exhibits strong-preg-robbing properties. It can adversely affect the process of gold recovery during the cyanidation due to its ability to adsorb, or preg-rob gold from the cyanide leach solution.Treatments of carbonaceous ores with chemical surfactants as blinding agents to limit preg-robbing have shown promising results but at the same time have demonstrated that, if not properly used, could have a strong detrimental effect on the gold recovery process. High dosages of surfactants used as passivating agents for carbonaceous matter could lead to unwanted partial passivation of the activated carbon added during the CIL process and severely impact the gold recovery. Optimal dosage for various surfactants would strongly depend on the ore mineralogy and the parameters of the pulp (temperature, pH, surface area and maturity of the carbonaceous material, etc).This paper describes an experimental study on the effectiveness of various commercially available blinding agents used to minimize the preg-robbing capacity of naturally occurring carbonaceous matter. The scope of the study was to: i) establish the optimum addition of blanking agent (surfactant) to minimize the preg-robbing capacity of the CM in the ore, and ii) establish maximum threshold amounts of blanking agents to be used before it negatively impacts the preg-robbing capacity of the activated carbon used in the CIL process. The study procedure involves standardized doping tests to evaluate the maximum preg-robbing capacity of treated CM, coupled with surface analysis with ToF-SIMS to monitor the presence and the degree of loading of these chemical surfactants on both the naturally occurring CM and the added activated carbon.INTRODUCTIONNaturally occurring carbonaceous material (CM) in gold bearing ores often exhibits strong-preg-robbing properties. Thus, it can adversely affect the process of gold recovery during cyanidation due to its ability to adsorb, or preg-rob gold from the cyanide leach solution. The preg-robbing properties of this naturally occurring carbonaceous matter can vary widely between ores, and within a single ore body (Dunne et al.,2013;Helm et al.,2009;Miller et al.,2005). The degree of preg-robbing related to the CM within an ore is defined by several parameters: total organic carbon (TOC) content, surface area, maturity (i.e., crystallinity) of the CM and the presence of various functional groups on the surface of the CM. Preg-robbing gold ores continue to be a significant challenge because of the lack of a single or universal solutions."

Jan 1, 2016

By H. K. Taylor

"As a mining engineer with over 50 years' experience in underground operations and mine planning, I appreciate the enormous amount of work that went into the paper; and despite an imbalance between geology-geostatistics and the profit-earning actions of mining and treating (possibly because of sponsorship only by the Geological Society), I agree with probably 85% of the detail. But the paper fails to build on its own sound foundations and, like many predecessors, drifts instead into idealism. Even the starting quotation from the US SEC Form S-18 is little more than a platitude. An American consultant (l) has observed: ""an evaluation that accepts ore reserves as guaranteed because their definition meets SEC criteria is an invitation to disaster"".Idealism enshrines at least two myths that have bedevilled definition over the last several decades. The first is that the only purpose of 'ore reserves' is to promise successful new mines, and that 'ore reserves' must necessarily follow feasibility studies.In practice, the identification of what is likely to be mined if a mine is started must often be done on broad economics long before the feasibility study, and there may be only little later flexibility. The second myth is that there can be a perfect deposit with a simple exploration-appraisal-development sequence (the paper's Figure 2) against which all inferiors can be matched. If the field of definition be regarded as a pyramid, the quest for perfection and the imposition of rigid promises upon the terms 'ore' and 'reserves' drive definitions so near the apex (or the bottom right corner of Figure I, if preferred) that little is left to define. The process is reminiscent of the legendary super-medicine, the one so powerful that the patient had to be in perfect health to take it!"

Jan 1, 1992

The steam-filtration process for dewatering solids involves the application of slightly superheated steam to a filter cake during filtration. The mechanism by which the technique promotes water removal has been deduced from bench-scale experiments on coal and on granular iron ore concentrates. The mechanism, along with some of the applications and limitations of the process, is presented. Introduction I N the steam-filtration process, slightly super-heated steam is applied to the filter cake during filtration to remove more water than can be extracted by conventional filtration. Although this process was developed by Burton for coal filtration (1), it should have far wider applicability; certainly, it could be used to treat any mineral product, because only low-temperature steam is needed and most conventional filtration equipment can be easily adapted to it. As few restrictions apply to this process, however, it is important that its more obvious advantages and disadvantages be appreciated and, especially, that the criteria on which economic evaluations can be based are understood.

Jan 1, 1965

By Arun Verma

Thermal energy storage offers a means of effecting significant costs savings and conservation of premium fuels. Na2SO4 has been found to be a good material for storing thermal energy in the medium-temperature range, mainly because of its dimorphic nature and high heat of transition. Basic data and development of the salt to a practically usable block are discussed.

Jan 1, 1978

By Frank Baczek, R. Q. Honaker, D. P. Patil, B. K. Parekh

Fine refuse slurry impoundment is a requirement for the coal industry to dispose the fines. Impoundment maintenance is an on going problem for the coal industry and its breakage creates environmental as well as financial problems. Deep Cone thickener technology which has been successfully applied in the alumina industry to dewater red mud was evaluated for fine refuse slurry. Preliminary obtained in a pilot-plant test showed that properly flocculated conventional thickener underflow slurry could be thickened to about 52.5 wt % solids and could replace belt filter press. The Deep Cone thickener was also found to dewater clean coal slurry to about 70 wt % solids. Further testing of the unit at other coal preparation plant is in progress.

Jan 1, 2004

In order to avoid impurity problem and enhance absorption/desorption kinetics of Mg-based compounds, nanostructured Mg-based compounds were synthesized from Mg, Ni and other elemental nanoparticles produced by hydrogen plasma-metal reaction. XRD and TEM results demonstrate that homogeneous nanostructured Mg-based compounds with less impurity were successfully synthesized by this method. DSC in hydrogen atmosphere, pressure-composition isotherm and the kinetics of hydrogen adsorption/desorption were investigated at different temperatures. The results show that the nanostructured Mg-based compounds can absorb hydrogen in a high speed at a low temperature.

Jan 1, 2005

By T S. Cochrane

This paper is based on observations made during a recent visit by the writer to three of the dust research laboratories .in West Germany, each .of which is mainly concerned with studymg the composition and character of the respirable dust produced in mines or at industrial sites. The three institutes are discussed as regards their orgamzat10n and duties, their methods of dust sampling and analysis, and recent trends in research and development. An extensive bibliography completes the paper. Introduction A RECENT trip to Europe to attend international conferences m Austria and m Belgium gave the writer the opportunity to visit a number of research laboratories and mines in Western Europe. The visits to the dust research laboratories in West Germany are the basis of this report. In Germany, cooperative associations formed prior to and since the turn of the 20th Century to promote the safety and welfare of their workers have recognized the effects of airborne dust on the general health of the labour force.

Jan 1, 1964

By Julián M. Ortiz

Uncertainty quantification of a spatially distributed variable at any scale can be handled through geostatistical simulation. Large computation time, storage, and post-processing of the realizations are required to obtain a final assessment of block uncertainty. Multi-Gaussian kriging is a flexible alternative to simulation. The idea is to compute the conditional distribution of uncertainty after normal score transformation of the original samples. Under the multi-Gaussian assumption, all marginal and conditional distributions are Gaussian, hence fully defined by their mean and variance. The parameters of the conditional distributions are obtained by simple kriging and can be back-transformed to the original units of the variable of interest. An estimate and any summary of uncertainty can be easily retrieved. The main disadvantage of performing multi-Gaussian kriging is that change of support is not straightforward, that is, calculating uncertainty of block grades. We propose a methodology to overcome this limitation by considering a matrix simulation to generate multiple probability fields. Each probability field is used to draw spatially correlated point values from the point-support conditional distributions, and multiple realizations of the average can be obtained. This permits the calculation of the average over the block and its uncertainty. These blocks may correspond to selective mining units or to volumes from longer production periods relevant for engineering decisions. They can even be disjoint blocks, such as when several faces are mined at the same time. POSTMG, a Fortran program to perform these calculations, is described and a case study is provided.

May 1, 2004

By Robert Boyd

The Diamond Markets ? Supply has continuously increased over the past 25 years ? However, global supply is expected to drop by 1 to 2% by 2015 ? Demand Driven Market ?Demand is expected to grow 3% annually through to 2015 ? Supply Squeeze Anticipated (2010 to 2015) ? Consumption is exceeding rate of discovery, mine development and reserve replacement ? These fundamentals are driving increased capacity and production at existing mines in South Africa, Botswana and Russia and new areas such as Canada ? Canada is now the third largest diamond producing country in the world ? These fundamentals are also driving record levels of exploration expenditures throughout the world with particular focus on Africa and Canada

May 1, 2006

By Ertugrul Alp

Alp & Associates - Who We Are ?? Canadian consulting company (1999-?) ?? Principal Consultant: Dr. Ertugrul Alp, P.Eng. ?? Over twenty-five years experience serving the chemical, mining, pulp & paper, energy, steel, and transportation industries, and government clients. ?? Ph.D. in Mechanical Engineering, University of Waterloo ?? Experience: ?? Westinghouse Canada, Atomic Power Division, Manager, Analysis and Modelling ?? Concord Environmental (later Bovar Environmental), Principal, Manager, Air Quality and Risk Assessment ?? Arthur D. Little, Associate Director, Safety & Risk Practice Leader in Canada ?? Member: NATO CCMS Pilot Project on Disaster Preparedness (1991-1993) ?? Chair: MIACC Risk Assessment Expert Committee, 1995-1999 ?? Member: MIACC Committees on Land Use Planning and Pipelines (1993-1998) ?? Member: CSA/Q850 Risk Management Standard Technical Committee ?? Member: CSA/Z1002 OHS Risk Assessment Standard Technical Committee ?? Member: CCPA/CSChE Process Safety Management Committee (1999-?) ?? Member: ISO-31000 Risk Management Standard Canadian Advisory Committee ?? Chair: CSChE Process Safety Management Committee (2005-2006) ?? Chair: CSChE Expert Committee on Risk Assessment (1999-2005) ?? CSChE 2007 Process Safety Management Award

May 1, 2008

By R. Scheepers

"Abstract -Mineral deposits and prospects of the Pan African Saldanian orogenic belt in the south­ western Cape Province South Africa, are reviewed. Despite the entire absence of operating base or precious metal mines in the area, this study has established at !east four metal associations that offer enticing exploration potential .The poly-phase deformed, low-grade metamorphosed volcano-sedimentary Malmesbury Group constitutes a complex, poorly understood supracrustal sequence that has been loosely subdivided into the Tygerberg, Swartland and Boland tectono-stratigraphic terranes by northwesterly trending fault zones. Syn- and post-tectonic granitoids of the Cape Granite Suite selectively intruded these terranes. Early S-types preferred the Tygerberg terrane whereas the later I-types dominate the remaining areas. Anorogenic A-type granites, however, occur in all three domains. Known metallization is directly or indirectly related to the intrusives, yet syngenetic deposits are conspicuously absent from the supracrustals. Four metal associations have been identified.•,Cassiterite-wolfrarnite (± Au, Cu, Mo, Fe-sultides) in quartz and quartz/aplite veins hosted by tourmalinized and locally greissenized S-type granite. Similar exo-granitic veins occur in proximal metamorphites.•,Juxtaposed disseminated, stockwork, breccia and vein style Cu-Mo-Fe-(Au)-sultide mineralization hosted by matie to intermediate intrusives of high K calc-alkaline, 1-type affinity.•,Cu-Mo-Au-sultides hosted by hydraulic breccia pipes, stocks and veins occurring in anorogenic A-type alkali feldspar granites and amphibole quartz syenites.•,Scheelite with minor Cu-Mo-sulfides and Au-associated with endo- and exo-skarns spatially related to I-type monzogranite, granite and alkali feldspar granite .The first three associations occur along the Yzerfontein-Helderberg-Zone, a 180 km lineament in the Tygerberg terrane, a zone exploited by syn-, late- and post-tectonic intrusives and their related mineralization. The fourth association is typical of the Boland terrane. The spatial and temporal relationships between the various metal associations is interpreted as the result of sequential intrusion of relative early high level S-type, followed by intermediate level I-type and finally anorogenic A-type granitoids during the evolution of a contracting continental margin arc and its inner arc. This plate tectonic setting suggests subduction in an easterly direction underneath the Kalahari craton. The spatial configuration of the various terranes at the present erosional levels is the result of rifting and significant differential vertical displacement following cessation of subduction, a terminal tectonic event possibly synchronous with intrusion of the A-type granitoids.Near surface preserved roof zones and cupolas of both S- and I-type granitoids in the Tygerberg and Boland terranes, respectively, render these areas extremely prospective for Sn, W, Mo and Au mineralization. The presence of intermediate to mafic volcanics, a diversity of calcareous lithotypes and favorable plate tectonic setting of the Malmesbury Group suggest potential for the thus far elusive VMS, MVT and Sedex base metal and minor precious metal deposits."

Jan 1, 1994

By J. Zollinger, J. R. Kennedy, J. H. Park, D. Daloz

"In order to improve the properties of cast Ti-Al alloys to replace Ni-based superalloys past the low pressure stages of aircraft engines investigations into inoculation for grain refinement were carried out. Previous work showed isomorphic self-inoculation using Ti-Al-Nb particles was effective for grain refinement, however the relatively fast diffusion of Nb in Ti-Al make it difficult to observe the mechanism of nucleation. An alternative alloy was developed in the Ti-Ta system for isomorphic self-inoculation, maximizing the Ta content to improve the particles survivability in the melt. The powder processing produced comparatively small inoculant particles which dissolved, however larger particles were seen to survive solidification. The density difference between the inoculant particles and melt resulted in an inhomogeneous mixing of the particles and the melt with larger particles found near the outer edges of the ingots. Variations on particle size and interaction time between the inoculants and the melt resulted in the Ti-Ta inoculant reducing the as-cast equiaxed grain size by a factor of two compared to non-inoculated samples as well as increasing the equiaxed fraction in the ingot.INTRODUCTION Lightweight metals are of particular interest in aerospace applications. The hot sections of turbines are dominated by blades made of nickel based superalloys. Recently the GEnx turbine introduced TiAl blades in the last low pressure stage of the turbine to reduce weight and improve fuel efficiency (Kim & Dimiduk, 1991). In order to carry these benefits deeper into the turbine the high temperature (>800oC) properties of the alloys must be improved. Current grain refinement methods to improve properties rely on boron additions which may not be applicable for all blades as brittle precipitates may be formed during processing (McCullough, Levi, Mehrabian, & Hyman, 1991). A novel grain refinement process was previously introduced called “isomorphic self-inoculation” using Ti-Al-Nb particles to successfully grain refine TiAl (Kennedy, Zollinger, Bouzy, & Daloz, 2016). In order to better understand the mechanism of this process an investigation was carried out using the same process but with a Ti-Ta alloy which is more stable in the TiAl melt than the Ti-Al-Nb."

Jan 1, 2017

By B. K. Mishra, Subrat Kumar Padhy, B. C. Tripathy, I. N. Bhattacharya

Manganese is a difficult metal to electrodeposit due to its high electronegativity and continues to possess unique process challenges. Manganese deposits of high quality are electrodeposited on 316 grade stainless steel from sulphate solutions in the presence of organic additives such as tetra ethyl ammonium bromide (TEABr), tetra propyl ammonium bromide (TPABr), and tetra butyl ammonium bromide (TBABr). The concentrations of these additives were examined over a relatively broad range to evaluate their effect on current efficiency, specific energy consumption and deposit morphology of the electrodeposited manganese metal. A maximum current efficiency of 68% was achieved in the presence of TEABr in the bath. X- ray diffraction studies revealed that (330) (411) planes were the most preferred planes of crystal growth during manganese electrowinning at a current density of 500 A/m2 resembling alpha-manganese irrespective of the nature of additive. Scanning electron micrographs showed smooth and uniform deposit morphologies when manganese was electrodeposited in the presence of TEABr.

Jan 1, 2014

By I Wilkomirsky, F. Parada, R. Parra, E. Balladares

"The neutral roasting of As bearing copper concentrates is confirmed well established and promising option for the treatment of this type of complex concentrate. The AS elimination by volatilization allows subsequent treatment of the calcines produced in a conventional pyrometallurgical process, by blending this product with standard concentrates.Several tests were performed using the fluidized bed pilot plant at the University of Concepción with different types of concentrates. Calcines, fines from two hot cyclones and flue dust from the ESP were collected. These materials were characterized using QEMSCAN® and the results used for the development of a mass and energy balance which took into consideration the specific chemical transformations that occurred in the reactor.A physico-chemical/kinetic model is proposed to explain the formation of bornite, chalcopyrite and magnetite. The mechanism involves solid-gas reactions between chalcocite, pyrrhotite and gaseous sulfur that without the mineralogical characterization would not have been possible to propose"

Jan 1, 2014

By J. Duby

"A description is given of a series of tests performed to determine the comparative effects which dynamic and static straining, in compression, have on the physical strength properties of mild steel and an aluminum alloy. The dynamic deformation was imposed during the passage of single stress pulses of about 100 micro-second duration. These pulses were recorded with strain gauges mounted near both ends of the specimen. The resulting records were analysed using a simple wave theory; there from the dynamic stress-strain curves for the respective metals were deter-mined and were then compared with the static stress-strain relation. The respective hardnesses of the metals after deformation are evaluates by means of static stress-strain curves in compression. The micro-structures of the metals before and after deformation are also shown. It is observed that dynamic de-formation considerably modifies the rate of strain hardening. This modified hardening appears to be persistent. The observed differences in physical strength properties and micro-structures are discussed in the light of the accepted dislocation theory for metals."

Jan 1, 1960

By M. Mahdi, L. So, A. MacMillan, D. Metcalfe, J. Woloshyn, D. Sauter, N. Uys, JP. Janse van Rensburg

For city smelters, with limited real estate, efficient slag cleaning furnaces followed by water granulation to produce an iron silicate product is the preferred process approach. Water granulation, however, consumes large volumes of water and requires high maintenance due to abrasive slag/water slurries. Air granulation offers an alternative to water granulation, which eliminates water use and has low maintenance requirements. Although full-scale operation has not been implemented for copper slags, full-scale operation for platinum group metal (PGM) converter slag has been implemented. A review of full-scale air granulation performance for PGM converter slag is provided. Based on PGM converter slag granulation performance, parallels to copper slag granulation are drawn and full-scale operation for copper slag is modelled using computational fluid dynamics (CFD). INTRODUCTION Typical slag management practices in the copper industry include dumping, slow air cooling, and water granulation, as shown in Figure 1. Dumping is the most commonly used slag handling method for most metal production plants, but presents challenges including the requirement for a large slag pit, requirement for expensive/high-maintenance “hot” mobile equipment, risks associated with transportation of molten slag, and no value recovery from slag as a sellable by-product or from slag as a source of heat.

Jan 1, 2019

By P. Pyykkö, E. Peuraniemi, J. Järvi, P. V. Latostenmaa, V. Törölä, S. Junnikkala

"Nickel concentrate smelting started in Harjavalta in 1959. First, flash smelting - Peirce-Smith converting route was applied, and the high-grade converter matte was further refined to nickel cathodes. In 1995 the original smelter flow sheet was simplified with the novel DON (Direct Outokumpu Nickel) technology. In Harjavalta with the DON technology, high-grade nickel matte with low iron content is produced in flash smelting furnace directly without subsequent converting stage. The metal values in the smelting slag are recovered in an electric furnace as an iron containing bottom alloy. Main special features in Boliden Harjavalta nickel smelter are smelting of high-magnesia concentrates, the high recoveries of nickel and copper, as well as those of PGM`s and cobalt.Sulfur and dust emissions to air can be seen generally as one main disadvantage of nickel smelting operations. In Harjavalta continuous improvements in environmental performance has been rewarded by minimum sulfur and dust emissions to the environment and working atmosphere. Today Boliden Harjavalta’s nickel smelter is presenting state-of-art-technology at nickel smelting.This paper describes the nickel smelter process and includes recent production and emission data. It describes features required to achieve environmental and occupational hygiene goals and compares environmental performance data to that published on other smelting operations. General description of New Boliden Way is presented and a case example of production stability project is also presented."

Jan 1, 2014

By M. W. Franklin, D. W. Hendriks

"Changing ore types, feed grades and c1rculat1ng loads are some of the many factors that can make flotation feed-back control difficult. To control a flotation circuit using conventional fixed-parameter control algorithms, one must either tune the controllers very often or tune the controllers to the middle of the normal operating range. The former approach is very time consuming, while the latter approach can lead to long periods of either very sluggish responses or highly reactive responses which can lead to instability. The problem becomes compounded if feed-forward variables are introduced, creating even more variables to tune. An alternative to a fixed-parameter control algorithm is an adaptive control algorithm. An adaptive control algorithm continuously retunes itself based on previous reactions to its changes. Feed-forward control also becomes much more viable because the algorithm will tune the feed-forward parameters and the feed-back parameters simultaneously. Using the combination of feed-forward and feed-back tuning is an effective way to decouple the loops needed in flotation circuits where one circuit feeds into another. The advantages of adaptive controllers over conventional controllers will be introduced through the use of a simulator. Also discussed will the be the implementation of adaptive controllers at Brunswick Mining and some of the modifications that are available to help solve more difficult control problems.Brunswick Mining is located just outside of Bathurst, New Brunswick. The concentrator processes approximately 10250 tonnes per day of ore that assays at approximately 8.9 %zn, 3.6 %Pb, 0.3 r.cu and I 00 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 34 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb."

Jan 1, 1986

By J. Moyes

The Intec Process is a generic process for the production of pure base metals and precious metals from sulphides concentrates derived from copper, nickel, zinc and lead ores. The development program for the Intec Process initially focussed on the treatment of copper concentrates, (the ?Intec Copper Process?), and more recently of zinc concentrates, (?the Intec Zinc Process?). Developed and proven in Sydney, Australia at a cost of US$15m over the last ten years, the Intec Copper Process is now ready for commercial application. The knowledge gained during the development of the Intec Copper Process has been applied to the Intec Zinc Process, which utilises the same basic chemistry to produce high purity zinc ingot from metallurgically complex zinc sulphide concentrates containing lead, copper, iron, silver and gold. The demonstrated ability of the Intec Zinc Process to treat low grade mixed zinc/lead/copper concentrates, including those with high iron and manganese levels, holds out the real prospect of overcoming major metallurgical hurdles that have long affected the zinc industry. The Intec Zinc Process consists of the three consecutive circuits of leaching, purification and electrowinning. The leach circuit is of single stage configuration with a series of reactors to which concentrate and lixiviant are fed. Purification consists of cementation and precipitation by pH adjustment. Electrowinning employs an electrolytic cell very similar in design to that of the Intec Copper Process, but differs in that a conventional plate cathode is produced. During electrowinning, the same mixed halide species (BrCl2 -, HalexTM) that is integral to the Intec Copper Process is generated in solution at the anode and exhibits powerful leaching characteristics capable of directly leaching the sulphide concentrate feed. The need to roast the concentrate prior to leaching, as is practised in the conventional Roast/Leach/Electrowin (RLE) process, is thus eliminated whilst a range of by-products (notably lead, copper and precious metals) can be extracted in the simple, single-stage leach. This paper describes the Intec Zinc Process; the technology, predicted economics and its environmental aspects.

May 1, 2002

By T. Möller

Grinding mills are the heart of the mineral processing plant, and are production-critical machines which are required to achieve high availability. Liner wear life and a liner design that promotes ease of installation are important variables to achieve a high level of mill availability. Increased mill size results in more mill internal surface to protect, and more liner components to install and remove. This drives designers toward an increase in liner size to minimize the number of components to be installed by the liner handler. The liner attachment method can also have a large impact on mill availability as well as safety during installation. This paper outlines the experience from the development, installation and follow-up of liners installed in two 38' x 45' AG Mills at Boliden Aitik in Sweden. A new Poly-Met shell liner concept has been developed to minimize the number of liner components. The new Poly-Met shell liner components are made much larger than conventional Poly-Met or steel liners. This reduces the number of components to be installed/removed by the liner handler and helps to minimize installation time and consequently down- time. A new attachment system has also been developed to eliminate the need for the installation crew to be in the ?drop-zone? of the shell liners while installing the liner bolts. One interesting aspect of this project was the requirement to predict liner life for these new large format AG mills. The existing 22' diameter mills at Aitik provided a base-line reference for this purpose, and DEM studies were used in the project development stage to predict the wear life of shell liners for the new 38' diameter AG mills. The results from this study are included.

Jan 1, 2012