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By George A. Guess

The making of contracts for the purchase of ores is a business which the metallurgist usually understands better than the miner. Companies in the custom ore business often employ an ore buyer who is aware of the class of ore which the smelter needs, and is thoroughly conversant with the business. The miner on the other hand makes ore contracts but seldom, and it is often only after a settlement has been made that he realizes the meaning of the terms of the contract under which he has sold his ores. He has expectations usually greatly in excess of the amount 'net proceeds' shown at the bottom of the settlement sheet. Seldom does the occasional shipper really know his contract. A somewhat similar parallel is to be found in insurance policies. We all have insurance policies; we never know the conditions contained in them until after the fire. The clauses in the policy are for the protection of the Insurance Company. An Insurance Company has no friends.

Jan 1, 1926

By G. Zeng

Although the solubility of oxygen in zinc electrolyte is less than 9 mg/L, the effect on deposit stability and zinc-dust consumption can be significant. Sodium sulfite is used to deoxygenate the electrolyte. The effect of the sodium-sulfite concentration on cobalt removal is investigated. The results show the reduction of sulfite to elemental sulfur that adhered to the zinc dust surface forming a passivating layer, and small amounts of sodium sulfite have no effect on cobalt removal. The optimum amount of sodium sulfite is 100 mg/L. It is an important consideration in purification circuits to use sodium sulfite as an additive to cobalt cementation.

Jan 1, 2005

By Matthew Violot

Vale Canada?s Birchtree Mine, located in Thompson Manitoba, has been experiencing problems with hanging wall / footwall dilution, as well as sloughing off of adjacent stopes and temporary stope block backs. Birchtree Mine is interested in determining how time affects the stability of their open stope blocks. Many factors simultaneously influence open stope stability (rock mass quality, joint condition, stress condition). This makes it challenging to determine the influence of a single parameter such as exposure time or stand-up time. This study focuses on determining the effect of exposure time on open stope dilution and combines stress analysis and empirical based approaches.

Jun 1, 2012

By L. Xia, B. Hart, K. Douglas1, S. C. Chelgani

Development work to optimize a flotation flowsheet for rare earth element (REE) recovery is underway. The original approach used alkyl phosphates and phosphoric acid ester as collectors to concentrate REE minerals. To improve REE recovery, hydroxamates as alternative collectors were investigated. In this paper, micro flotation of REE minerals using salicylic, benzoyl and naphthoyl hydroxamates is reported. Unlike phosphonic collectors, slime removal does not show a significant effect on REE recovery when using hydroxamates as collectors. Among the three hydoxamates, the grade of La, Ce, and Nd for concentrates produced by salicylic hydroxamate is the highest. The recovery response with naphthoyl hydroxamate is similar to that of salicylic hydroxamate; good grades for La, Ce, and Nd, less effective for Nb, Y, and Zr. The data indicated an affinity by salicylic and naphthoyl hydroxamtes for LREE over the HREE minerals. In comparison, benzoyl hydroxamate indicated an affinity for Nb, Y, and Zr. Temperature effects on REE recovery were also studied. The grade and recovery of REEs generated by flotation using a mix of salicylic and benzoyl hydroxamates at room temperature was almost identical or even better relative to the recovery using naphthoyl hydroxamates at elevated temperature.

Jan 1, 2014

By S. McCarthy, K. E. Waters, A. Jordens

The beneficiation of rare earth (RE) element bearing minerals has become an active area of research as applications for these elements grow while the supply to non-Chinese consumers is restricted by export quotas. One of the most interesting beneficiation techniques for RE minerals is froth flotation as their unique chemistry suggests that collectors with a specific affinity for RE cations should be able to selectively recover these minerals. Existing literature, focusing mainly on bastnäsite flotation, identifies hydroxamic acids as excellent collectors for RE minerals. The high stability of hydroxamate-RE cation complexes is the explanation most often offered for the observed selectivity of these reagents in bastnäsite flotation however some research has also suggested that mineral solubility plays a crucial role in the success of hydroxamic acid flotation of RE minerals. This work investigates the interaction of allanite, a relatively insoluble RE-silicate mineral, with benzohydroxamic acid using zeta potential measurements and microflotation. The effects of Fe(III) and Fe(II) ions as potential activating ions (cations that form stable hydroxamate complexes) on benzohydroxamic adsorption to the allanite surface are investigated as a potential solution to promote hydroxamic acid adsorption. The results indicate that the optimum conditions for separation of allanite from quartz occur at pH 4 using FeCl2 as an activator for benzohydroxamic acid adsorption.

Jan 1, 2014

By Maria Skyllas-Kazacos

The All-Vanadium Redox Flow Battery that was pioneered and has been developed at the University of New South Wales (UNSW) in Sydney since the mid-1980s is currently regarded as one of the most attractive energy storage systems for large-scale implementation in a wide range of grid-connected and offgrid applications. Several companies are now manufacturing and installing MW-scale VFBs in applications ranging from renewable energy storage, load-levelling, emergency back-up power and power arbitrage. The full-scale uptake of the VRB in commercial energy storage systems however, is heavily dependent on the availability and cost of vanadium used in the VRB electrolyte. Cost is also a function of purity requirements and although there is little scientific evidence on the effect of impurities on the VRB life and performance, VRB developers continue to demand high purity vanadium at considerable cost. This paper will provide a brief overview of the current understanding of electrolyte impurities on VRB performance together with an economic analysis of the impact of vanadium prices on overall VRB capital and levelised costs for a range of applications.

Jan 1, 2014

By Stephen B. Hearn

The SLon Vertical Ring and Pulsating High Gradient Magnetic Separator was developed to overcome multiple disadvantages associated with traditional horizontal type Wet High Intensity Magnetic Separators (WHIMS) which have been in service for many decades for recovering iron ore and other minerals. Proven successful, with hundreds of units now upgrading low-grade iron ores and maximizing recovery of fines throughout China, the technology is now being tested in the Western world. This paper will discuss the drawbacks of traditional WHIMS, explain the operation of the SLon, and illustrate its practical use in processing hematite ores.

May 1, 2007

By Nadarajah Nanthananthan

Mine backfill has been widely used as a means of ground support. While proper design of backfill is important to ensure ground stability, understanding the failure mechanism and the various influencing factors in a filled block is essential. This paper presents a modified sliding failure model of a confined backfill block. The model considers both the gravity load of the backfill itself and the overlying load from fragmented ore or backfill on the top. A series of new equations were derived and the relationships between factors such as factor of safety, friction angle, cohesion and the exposed stope height were developed. This modified model will be a very useful tool in backfill design, for example, to optimize the design of backfill for a given stope geometry or to determine the maximum backfill height for a particular type of backfill.

May 1, 2007

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 A. Scheltema Beduin, M. Kalisch, E. Floch, R. J. Dijkhuis, H. J. Oterdoom

In metallurgical copper production, the traditional aim is to increase recovery of copper to the maximum. SMS Siemag (SMS) has supplied numerous furnaces for this application. New targets are to make sure end of line products are as safe as possible with respect to health and environment, and to maximize raw material utilization. This means a for example a minimization of leachable metals in slag, so it can be safely used as a construction material, and either a targeted concentration or fixation of volatile compounds, such as arsenic. Currently, 2 process routes are generally applied for slag cleaning. The first is grinding followed by flotation, and the second is slag cleaning in an (electrical) furnace. Popularity of both options has fluctuated over the years, and currently the milling-flotation seems to be the more popular option. In this article some of the advantages and disadvantages of both methods are described, and especially how long term environmental policies could have an impact on the decision which process route to choose. Finally, this article will describe some of the developments SMS is working on in pyrometallurgical slag cleaning that could influence the direction for the design of the copper plant of the future.

Jan 1, 2014

By J. A. Finch, A. M. Elmahdy

Blending frothers is becoming common in flotation practice apparently enhancing performance. However, there have been no studies to understand the blend mechanism. In this paper, the effect of two frother blends ofF150 (polyglycol) with MIBC or pentanol (both alcohols) on bubble size, gas holdup and froth height is reported. The blends focused on a small addition of the polyglycol to the alcohols as base frother. The tests showed that the bubble size at blend concentration below the critical coalescence concentration (CCC) of the base frother was decreased but was significantly larger above the base CCC. Froth build-up showed a strong synergistic effect.

Jan 1, 2009

By K. Tsuchihashi, A. Kishimoto, T. Uda, Y. Kado, S. Maruyama

We recently proposed a continuous production process for titanium metal with some experimental results. In the process, titanium tetrachloride is reduced by Mg in the presences of Bi to form a Bi-Ti alloy at 900ºC. At this temperature, the obtained alloy is liquid and allows for the continuous removal of product and heat from the reaction vessel. The obtained Bi-Ti alloy was vacuum-distilled at 1000ºC for 24 hr, and 98 at % (92 wt %) titanium, which was easily crashed to powder, was obtained. Bi solvent was selected because of the highest titanium solubility at 900ºC and the moderate vapor pressure among the candidate metals (Bi, Sn, Pb, Zn, and Sb).

Jan 1, 2014

Thermal barrier coating (TBC) systems provide thermal insulation to high temperature for aero¬propulsion. A fracture mechanical model developed earlier for multilayer systems is applied on TBC to realize superior performance by enhancement of fracture resistance. Functionally gradient materials (FGM) solution concept is the basis of approach followed here. A few realistic FGM TBCs are considered in the analysis in addition to a conventional TBC as the base case and a hypothetical worst case with YSZ-YSZ interface. Parameters like number, composition and thickness of graded layers and elastic modulus are considered for the analysis and quantitative improvement of fracture resistance of TBCs. The analysis is confined to deep crack with crack size to width ratio as 0.5.

Jan 1, 2010

By C. A. Biley

"A dedicated iron removal stage was installed at Anglo American Platinum’s Rustenburg Base Metals Refiners (RBMR) during an expansion project which began execution in 2010. The Pressure Iron Removal (PIR) process aims to precipitate iron from a nickel leach solution under medium temperature (145 °C) oxidative conditions using caustic for neutralisation. Since commissioning, the process has been robust in removing iron from the refinery but has shown significant variability in the residues produced. These residues, which are typically comprised of ferrihydrite, hematite or natrojarosite, have varying iron contents and different physical properties which have implications for their filtration and ultimate removal from the refinery. Since over 95% of nickel plated at RBMR passes through the PIR section, volumetric constraints caused by poor filtration performance directly influence nickel production and stabilisation of this process remains central to the continued ramp-up of the refinery to full nameplate capacity. This paper details the development of the PIR process and the journey from concept to implementation. Recent laboratory and plant scale tests have highlighted the importance of the initial phase formed in the autoclave for the ultimate residue requiring filtration and how the feed acid concentration is a critical control parameter. On this basis, a new caustic dosing philosophy was implemented which improved pH control in the autoclave. Further optimisation of the PIR process is on-going.INTRODUCTIONIn 2010, an expansion of Rustenburg Base Metal Refiners (RBMR) to increase nickel production from 21 to 33 ktpa began execution. The management of iron was pivotal in the ultimate configuration in the new circuit and one of the primary differences from the original circuit was the addition of a dedicated iron removal stage: Pressure Iron Removal (PIR). A significant drive for this new unit operation was to facilitate the separation of iron from other leach residues. Not only did this result in a significant decrease in the amount of leach residue but, without the constraints associated with iron precipitation during leaching, has permitted more aggressive leaching conditions and, correspondingly, greater throughput and efficiencies.However, as with many commercial implementations of even mature technologies, the journey from development to implementation has presented challenges for the continued ramp-up of the refinery to full nameplate capacity. Specifically, since all nickel bearing leach solution must pass through the PIR section prior to the nickel purification and recovery circuit, throughput difficulties in the PIR section can directly impact supply of feed to the nickel tank house. Since commissioning, the PIR autoclave has effectively removed iron from the refinery, but has shown significant variation in the solids phases produced in the autoclave. This variation presents difficulties for the filtration of the discharge slurry and represents a key throughput limitation which periodically impacts production. Additionally, the increasing production rates associated with the ramp-up of the refinery have resulted in a significant increase in the required volumetric throughput through the PIR process. This has placed even greater emphasis on improving the stability of the solid phase produced in the autoclave, ultimately targeting an easily filterable residue with high iron content."

Jan 1, 2016

By Alan R. Holt

"This paper provides an overview of the use of uranium and coal in Ontario Hydro's generation program. The dynamics of available supply sources including mining and transportation infrastructures and regional considerations are described. Included is a discussion of needed procurement strategies, both in place and planned, to meet fluctuating fuel requirements while ensuring adequate supply security and cost effectiveness. IntroductionDuring the first half of this century, Ontario Hydro or the Hydro Electric Power Commission of Ontario, as it was then known substantially supplied all of the province's electricity needs from a large number of hydraulic generating stations. Although hydraulic power still provides a very significant part of Ontario energy requirements, this paper will concentrate on the role of uranium and coal in their generation program. To provide a perspective on the importance of these two fuels, Figure I shows the approximate value of each for the past few years in relation to Hydro's total operating costs. The trend toward increasing nuclear output and a corresponding decline in coal use is also clearly illustrated.Figure 2 shows the currently installed capacity of their three main energy sources, hydraulic, nuclear and coal and the 1986 production totals for each, followed by Table I which compares the average operating or running cost on the basis of dollars per megawatt hour for each type of plant. It demonstrates dramatically why Ontario Hydro base load s its hydraulic and nuclear plants, and why coal has become the swing fuel on the system. Although they have a 1200 megawatt plant in Toronto with natural gas-burning capability, and a 2000 megawatt oil-fired station near Kingston, both are presently mothballed and have not been considered in this paper.This paper starts with a user's perspective of the nuclear fuel supply situation which will be discussed in relation to the usual considerations of security, flexibility and cost."

Jan 1, 1988

By Jerry Ran

When multiple levels are mined in open stope mining with delayed backfill, mining underneath fill is inevitable to achieve higher rate of recovery if no sill pillars are left for the purpose of fill separation or partial ground support. This is particularly true when the orebody has low reserves per unit vertical distance. Instability of the exposed fill back causes stope dilution, production delay and possible equipment damage and consequently increases the mining cost. Previous studies have concentrated on fill mat stability in cut-and-fill and stability of fill walls in open stope mining. Workers are exposed to the fill back in cut-and-fill and therefore smaller open spans are normally adopted and the fill mat is reinforced. In open stope mining openings with large spans are designed, workers are not exposed to the fill back and its stability has to be maintained by fill of sufficient strength. However, the required fill strength is normally determined by considering different modes of fill wall failure. The fill back stability is usually not analyzed in the fill design process. The lack of analysis on fill back stability for open stope mining is mainly due to difficulties in relating the fill properties to the fill and stope geometry. In this paper a simplified wedge model is adopted to analyze stability of the exposed fill back in open stope mining with consolidated backfill. The proposed method calculates the factor of safety of the fill back against shear failure under known fill and stope geometry and fill strength parameters in order to assess the fill back stability. It can also be used to determine the required fill strength with known fill and stope geometry. The proposed approach is indirectly validated by mining experience and observations at two operating mines. In addition there are many factors affecting the fill quality and stope configurations in an operating mine. These factors have to be considered in the analysis of fill back stability. This situation is highlighted by presenting an actual mining case where the fill back failed due to factors commonly encountered in mining operations.

May 1, 2003

By Michael Klichowicz, Holger Lieberwirth

"For a detailed prognosis of mineral comminution processes, simulation tools like DEM still pose various challenges. Less realistic mineral structures can affect the results of simulation models such as bonded-particle models (BPM). Hence, in order to design mineral processes with these models as tools, representative mineral input data should be used. The article shows, how realistic 2D-structures can be modelled by taking advantage of the parameters identified by the Quantitative Mineralogical Analysis (QMA). Important quantitative parameters can be derived by analyzing three orthogonal thin or polished sections. For this reason point, line, and area analysis are applied. The mentioned parameters precisely describe the texture and structure of minerals. The newly developed software is able for the first time to semi-automatically analyze images of mineral structures using QMA. Moreover, statistically equivalent structures of minerals can be modelled using the QMA- parameters. Generating synthetic, but equivalent mineral structures opens the door for more reliable BPM based simulations. Within future research, the procedure will be adopted to generate 3D-structures. Therefore, QMA-based routines that already have been applied to generate 2D-models shall be utilized as basis. The aim of this procedure is to synthesize realistic microstructures based on certain statistical figures in order to improve comminution simulations.INTRODUCTION Due to its increasing capability, the use of computer technology is permanently intensifying in the design of mineral processes. The recent past has impressively shown that computer models can enhance the understanding of mineral processing. There is in fact a rising number of research activities, which are using simulation approaches to study various aspects of it. Weerasekara et al. (2013) give a comprehensive overview over the application of discrete element modelling (DEM) in the science of comminution.Nonetheless, using simulation tools such as DEM in general still poses a challenge. For a detailed simulation of a mineral comminution process with DEM, bonded particle models (BPM) appeared suitable in the past. The following issues, however, affect an appropriate prediction when modelling with BPM:• Simulations with high numbers of particles may need a lot of time for computation. • Internal modeling parameters like the spring and damper constants in DEM have to be adjusted by comparing its specific crushing behavior in the simulation to reality.• In order to use DEM for prediction of mineral processing, it is essential to validate the correctness of the models and assumptions, which is sometimes difficult. As Weerasekara et al. (2013) have stated it is crucial that the DEM method as well as the DEM code work properly.• It is challenging to implement the complex geometric structures of real minerals into the model."

Jan 1, 2016

By Mike Anderson

The annual budget for the repair and maintenance of equipment at Syncrude Canada Ltd is in excess of 450 million dollars. Of this amount, a significant portion can be attributed to the loss of material on various pieces of equipment throughout the operation. In order to effectively battle the different wear and corrosion mechanisms that lead to material loss, it is important to understand how materials behave in the environments in which they are used. Through the work carried out at Syncrude, and work conducted with various external collaborators, significant improvements in both equipment reliability and productivity have been achieved. This paper will review some recent field trails where materials research has demonstrated the potential for significant improvements in equipment run life and reduced maintenance costs. These field trails will demonstrate the need for understanding the interaction between various damage mechanisms and the materials used in different services. The paper will also discuss current areas of focus along with future directions for further work.

May 1, 2003

By R. K. Carnochan

MANY improvements have been made in recent years in the milling of industrial minerals and it is the purpose of this paper to review some of the more important innovations that are now being used in the preparation of these products. Some of the observations which will be made have been prompted by what was seen on a recent trip to industrial mineral milling plants in the north and central sections of the eastern United States. The flotation plants visited were those of the Valley Forge Cement Company at West Conshohocken, Pa., the International Agricultural Corporation at Mount Pleasant, Tenn., and the Aluminum Ore Company at Rosiclare, Ill. Besides these, sand plants in Pennsylvania, West Virginia, and Ohio, coal-cleaning plants in Pennsylvania, pyrophyllite, mica, feldspar, clay, and kyanite plants in North Carolina, and a zinc mill and the Tennessee Valley Authority ceramic laboratory in Tennessee were visited. The milling of industrial minerals can be considered under three broad headings, namely, crushing, grinding, and purification. Usually there is both a separation and grinding problem in treating an industrial mineral, but the problems are distinct, although sometimes a separation is made while grinding, as in the case of a Raymond throw-out mill, which grinds and at the same time throws out most of any hard material present in its feed.

Jan 1, 1939

By Free. Michael L.

Crushing ore prior to heap leaching enhances mineral liberation and creates fine particles that may require agglomeration to avoid permeability problems during leaching. Conventional modeling is relatively successful in describing general fluid flow and extraction in heaps. However, most models do not adequately account for the effects of mineral liberation and exposure or the effects of agglomeration, curing, and loading on heap leach performance. This paper will discuss methods to account for mineral liberation and exposure as a function of comminution. It will also discuss methods for incorporating liberation, exposure, and mineral locking as well as curing and fluid flow in heap leach modeling. It will also provide information regarding agglomeration and the effect of loading in heap leach modeling.

Jan 1, 2014