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By Dale C. H. Nevison

One of the most intensive of material rivalries is the confrontation between zinc die castings and plastic injection moldings. Pressed hard by the plastics industry, zinc die casters are learning how to make parts with less material yet without sacrificing quality. The key to this new trend is the technique of Thin Wall die casting. The obvious benefits of Thin Wall are lighter weight and lower cost. Again, obviously, these are the very selling points that put plastics into many appliance and automotive parts formerly made of zinc. One of the factors that has been most conducive to the outstanding growth of plastics has been the increasingly prevalent concept that "adequate" properties are sufficient, especially if there are cost advantages. Most of modern design today is oriented around the reasonable life of a product, rather than indefinitely extended life. This is simply an acknowledgment of the existence of a design environment that pervades many areas, reflecting the life-cyclic desire for change. Too often, so-called "weight-saving" materials end up being very costly - not only in production, but in durability and dependability. Change for the sake of change usually doesn't effect a change for the better. In the majority of cases, the best bet is to design in traditional materials and minimize the material needed, while maximizing the efficiency of the production process. Component prices of products to be produced from either plastics or zinc must be studied in detail to determine which material will produce the lowest cost of manufacture. It is not uncommon for two parts, similar in appearance at a casual look, to have a considerable difference in energy requirements and production costs. Detailed cost estimates of the advantages of each material should therefore be prepared for zinc and plastic parts before the final design and material selection decisions are made.

Jan 1, 1978

By J. R. Andrews, R. P. Young, J. M. Reyes-Montes

"Microseismic monitoring provides insight into the location and extent of rock-mass fracturing induced by cave mining, enabling interpretation of the cave profile and validation of predictive numerical models. Source location uncertainties can lead to misinterpretation of the inferred characteristics of the fracture network. One principal source of uncertainty is the velocity model used to invert the location algorithm. Large-scale 3D numerical models of modulus changes across a caved mass can represent such complexities in the location algorithms, allowing more accurate interpretation of the microseismic activity. A Northparkes mine case study applies this advanced approach to microseismic data interpretation.RÉSUMÉ Le suivi microsismique fournit des renseignements sur la localisation et l’étendue des fractures de la masse rocheuse induites par l’exploitation par blocs foudroyés; cela permet d’interpréter le profil de la chambre foudroyée et de valider les modèles prédictifs numériques. Les incertitudes quant à la localisation de la source peuvent conduire à des mésinterprétations des caractéristiques inférés du réseau de fractures. Une des principales sources d’incertitudes est le modèle de vitesse utilisé pour inverser l’algorithme de localisation. Des modèles numériques tridimensionnels à grande échelle des changements du module d’élasticité à travers une masse foudroyée peuvent représenter de telles complexités dans les algorithmes de localisation, permettant ainsi une interprétation plus juste de l’activité microsismique. Une étude de cas à la mine Northparkes applique cette approche avancée à l’interprétation des données de microsismicité."

Jan 1, 2016

By D. A. Temple, G. O. John

Until recently, the approach to the problem of treating complex ores bas been to produce, insofar as is possible, mono-metal concentrates which are treated in traditional zinc, lead and copper smelting circuits, with the residues and by-products from some of these circuits being retreated for the recovery of contained values either by a separate residue treatment process or along with the primary feed to the appropriate circuit. The continued development of the Imperial Smelting Process, with its ability to treat poly-metal concentrates, calls for a re-examination of the traditional approach to this problem, and this the paper attempts to do. A survey of recent progress in the technical development of the process is made and a summary of current operational performance is included.

Jan 1, 1971

By V. Vakiloroaya

The paper aims at developing a hybrid solar-assisted air conditioner system for performance enhancement and energy efficiency improvement. To increase sub-cooling of the refrigerant at partial loads, we propose a new discharge bypass line together with an inline solenoid valve, installed after the compressor to regulate the mass flow rate of the refrigerant vapour passing through a hot water storage tank. For control design, a lumped parameter model is first developed to describe the dynamics of the system in an explicit form of input-output relationship. The system has been fully-instrumented to examine its performance under different operation conditions. The system model is then validated by extensive experimental tests. The predictions from the models exhibit a good coincidence with experimental results, judging by an RMS error less than 15%. Based on the obtained dynamic model, a linear quadratic regulator (LQR) is applied to optimize a cost function of the output errors and control efforts. The key challenge is to regulate the refrigerant temperature entering the condenser by controlling the valve opening. The design approach is then tested in a transient simulation tool to predict the system performance in transient conditions. The experimental results obtained from implementation with PLC demonstrate that the proposed system delivers higher system efficiency owing to the higher refrigeration effect in the direct expansion evaporator. Thus, the novel development is promising for improvement of energy efficiency, enhancement of the system performance while fulfilling the cooling demand. Consequently, between 25 and 43% of monthly electricity can be saved on average.

Aug 1, 2013

By A. Broussaud

The paper describes the advanced grinding control system implemented at Newmont Ahafo gold mine, Ghana in 2009 and 2010. It shows how the different components of the Advanced Process Control (APC) system cooperate for increasing plant performance. The SABC circuit processes hard rock from different pits mixed with a variable proportion of oxides. The control strategy is designed to address specific disturbances, including start/stops of pebble crushers, unavailability of oxides, changes in rock size distribution resulting from segregation in the stockpile, and changes in ore type and hardness. The system consists of an expert system per se with extensive use of fuzzy logic, supplemented by an online dynamic model of the process used as a soft sensor, a VisioRock? rock size measurement system over SAG mill feed before addition of recycled pebbles, and an AudioMill? system to analyze the SAG mill sound and detect impacts on liners. All these components are embedded in the same OCS© software platform, which, among other benefits, makes it easy to support the entire system remotely. The paper details the physical constraints and the variables that are manipulated. It describes the control strategy and the contribution of each component of the system. It also describes the project implementation and the performance of the system. In addition to a strong involvement and support of management, the very good acceptance of the operators has been facilitated by the remote access system that made it possible to immediately modify the system each time it was needed during the baby sitting phase. The system made it possible to increase gold production significantly through increases in tonnage and recovery thanks to a better control of the grind size through a stabilization of the secondary ball milling circuit and an improvement of the operating conditions of the classifying cyclones.

Jan 1, 2012

By Chris Rule

This paper tells the story of the rapid commercial application of stirred milling technology at Anglo American Platinum?s many Concentrators. The first stirred mill ? a 10 000 litre IsaMillTM; the largest at the time, was commissioned in late 2003. The project development work was presented at SAG 2001. This operation was ?proof of concept? and vindicated the decision to scale up the technology; allowing a rapid and extensive roll-out of mainstream regrind mills as well as several further flotation concentrate regrind mills, over the next six years. Currently 23 stirred mills are in operation with 64 MW of installed drive capacity ? this paper describes the projects? roll-out and the significant results achieved to date. Many operational problems have been solved along the way, some of these will be described. The introduction of the technology has seen a step change in metallurgical results and progressively decreasing operating costs.

Jan 1, 2012

"8.1. IntroductionThe stoichiometry of most named platinum-group minerals (POM) is known (cf. Cabri, 1981b, in Chapter 7), but, because these minerals are subject to a wide range of element substitutions, representative analyses require treatment in a separate chapter (section 8.2). The analyses, in all cases done by electron microprobe, are grouped in sections according to the principal platinum-group element (POE) for each POM, and then follow sequentially with increasing amounts of the principal POE starting with the ideal composition, when known. In order to facilitate reference to specific POM by name, an alphabetical listing is also given (Table 8.1). A range of compositions, in addition to one or several ""representative"" analyses, is given for some POM when more than one analysis has been reported for a particular locality. The tables of POM analyses (Tables 8.2 to 8. 76) include at least one analysis for every locality for which data have been published, to the best of the authors' knowledge. All analyses are referenced for locality and publication source, and include several unpublished analyses (all but one done at CANMET). Most analyses have been rounded off to one decimal place for amounts more than one per cent and their formulae calculated on the basis of an even number of total atoms. In all tables, ''n.d.'' stands for elements sought for but not detected and a dash signifies elements not sought, or when these haven't been specificed in the publication source.Section 8.3 contains tabulated analyses and, in some cases, also includes a critical assessment of POE-bearing minerals in which the POE occur in trace or minor quantities. The organization of the data in this section is by mineral groups; e.g., sulphides, sulpharsenides, silicates, etc. Some of these data are also discussed in Chapter 4 by Crocket (1981) and are discussed briefly in Chapter 6 by Crocket and Cabri (1981)."

Jan 1, 1979

By Daniel Lachapelle, Nuri Hmidi, Turgut Yalcin

"Simulation can serve as a convenient tool in studying the behaviour and performance of grinding circuits by facilitating the evaluation of various scenarios and identification of optimum operating conditions. This technique was applied to the St Andrew Goldfields Ltd.’s Stock Mine Mill which is a 1300 tpd gold milling facility, offering custom milling services as well as processing the Company’s own ores. Lack of adequate instrumentation in the mill poses a challenge in attaining optimum performance especially with changing ore types and characteristics. The grinding process is monitored essentially by manual measurement and adjustment of pulp densities at various streams. A simulation program was designed to assist in the effective implementation of this mode of grinding control. Product sizes from both the primary and secondary grinding circuits were correlated empirically to relevant process variables using a database formed from the results of past sampling campaigns. The simulator was created in Microsoft Excel whose data analysis and optimization tools coupled with its Visual Basic Programming capabilities were found to provide an excellent environment for the development of a cost-effective, efficient and user-friendly simulation program.INTRODUCTIONGrinding is often a very costly unit process in milling operations, mainly due to the excessive energy consumption associated with it. For example, for a Canadian copper-zinc flotation mill, grinding was listed as being the most costly item taking up 30.4% of the total milling expenses, followed by the flotation cost at 2 1 .O% (Kidd Creek Mines Ltd., 1982). A survey on 45 copper flotation mills around the world showed the average grinding cost to be 34.5% of the total milling cost (Weiss, 1985).Overgrinding aggravates the cost issue, while insufficient grinding either causes loss of valuable minerals to tails or results in low-grade concentrates. Therefore, it is essential that grinding circuits be carefully controlled and monitored. To this end, a great deal of effort has been devoted over the years to the modelling and simulation of grinding systems in order to assist in the efficient running of these processes."

Jan 1, 2001

By S. A. Scott

In 1913, potash mineralization was recognized at a depth of over 7,000 feet in an oil-well hole (Norcanol's Radville No. 1 well) drilled near the town of Raddlle, Saskatchewan. Although, at this depth, potash is not considered mineable by conventional underground mining methods, this discovery shed the first light on the potash deposits of Saskatchewan in much the same manner as oil-well drilling was responsible for the first discovery of potash in the Carlsbad Basin of New Mexico in 19:25. The discovery near Radville alerted the oil-well geologists and, as a result potash mineralization was recognized in the Verbata No. 2 well, near Unity, Saskatchewan, in 1946. The mineralization, which was at a depth ?of 3,466 feet, graded more than 20 per cent K20 over a thickness of eleven feet. This discovery, as its depth, thickness and grade were all amenable to mining,

Jan 1, 1963

By J. A. Brothers, M. R. Foran

"AbstractThis paper reviews the progress made in the manufacture of hydraulic cement from iron blast-furnace slag by simply grinding the granulated material with other constituents. The influence of the chemical and mineralogical composition of the slag, the conditions of granulation, the manner of drying, and the fineness of grinding, on the hydraulic properties of the cement, is discussed. The effect of additions of lime, portland cement, and anhydrite, alone and in combination, on the physical and cementing qualities of the mortar and concrete made from Sydney blast furnace slag, is shown in tables of data and is reviewed in some de- tail. The work at the Nova Scotia Technical College has shown that a cement equivalent in every respect to portland cement can be made from basic blast furnace slag- by the us2 of certain quantities of portland cement as an activator.IntroductionBlast furnace slag is a potentially valuable material for the manufacture of hydraulic cement. It is a by-product of the manufacture of iron in the blast furnace, and is formed by the combination of the silica and alumina .of the iron ore with the limestone flux. The metallurgist terms a slag .acid or •basic according as the percentage of lime is less or greater than the percentage of silica plus alumina. The basic slags have the •more pronounced hydraulic properties."

Jan 1, 1950

By A. Rao, J. A. Davidson, B. L. Jones, K. W. Bowes, D. Craib

Supported by ANSTO, Groundwater Science and Inception Consulting Engineers, Boss has embarked on a series of technical projects aimed at reinforcing the Project’s capability to meet its export permit production capability. This paper will focus on three aspects of this technical program: Reducing the cost of resource expansion through smart use of low cost, surface target generation techniques; Improving the rate of uranium leaching and solution stability (gypsum, jarosite) through lixiviant chemistry modifications; and Development of an ion exchange (IX) process to increase production capacity, and integration of IX and the current solvent extraction circuit with the existing uranium precipitation and product preparation circuits.

Jan 1, 2020

By Dwayne D. Tannant

The Adra tunnel near Naramata BC experienced a fire in 2010 that burned timber sets within the tunnel and caused severe spalling of rock from the roof and tunnel walls. The nature of the damage is documented and efforts completed to rehabilitate and open a portion of this tunnel to the public are described. The use of shortcrete and rock bolts is a technically and economically superior support system to timber sets as well as being far more fire resistant.

Jun 1, 2012

This paper describes the results of a laboratory study on the upgrading of Algoma siderite by the amine flotation of silica and silicate gangue. The experiments indicate that a virtually complete removal of silica is possible in a rougher flotation con-ducted in tap water at natural pH, without prior desliming of the ore. Grinding considerably finer than the apparent liberation size is essential for maximum silica rejection. A cationic collector, Aeromine 3037, gave best results when used in combination with a modifier. Of the several modifiers tested, a Dutch potato dextrin, Dextrin 4356, was found to be the most effective. Both iron recovery and the grade of the final iron product are enhanced by floating the pyrite contained in the ore prior to the amine flotation of the silica, and by scalping the magnetics from the silica concentrate. F OR over twenty years, the Algoma Ore Properties Division of The Algoma Steel

Jan 1, 1963

By Jr. Jones

This paper is derived from a document that compiles autogenous and semi-autogenous mill installations worldwide, through the end of 2010. Updates have been solicited from all major mill manufacturers and most have responded. A review of AG/SAG mills sold to date and in the last five years indicates that the AG/SAG mill market is very healthy and the trend is larger diameter mills with high diameter-to-length ratios. Ring motors (gearless) are the preferred drives for large mills even though the power transmitted through a gear drive is expected to near 11,000 kW per pinion in the near future.

Jan 1, 2012

By K. Liu

"In the present work, two-step heat treatments with preheating treatments at different temperatures (175, 250 and 330°C) as the first step followed by the peak precipitation treatment (375°C/48h) as the second step have been performed in Al-Mn-Mg 3004 alloys to study their effects on the formation of dispersoids and evolution of elevated-temperature strength and creep resistance. During the two-step heat treatments, the microhardness is gradually increasing with increasing time until to a plateau after 24 hours when first-treated at 250°C and 330°C while there is a minor decrease with time at 175°C. Results show that both the yield strength and creep resistance at 300°C reach the peak values after the two-step treatment of 250°C/24h+375°C/48h. The formation of dispersoids is greatly related to the type and size of pre-existing Mg2Si precipitated during the preheating treatments, in which that coarsened rod-like ß’-Mg2Si strongly promotes the nucleation of dispersoids while finer needle-like ß’’-Mg2Si has less influence. Under optimized two-step heat treatments and modified alloying elements, the yield strength at 300°C can reach as high as 97 MPa with the minimum creep rate of 2.2×10-9 s-1 at 300°C in Al-Mn-Mg 3004 alloys, enabling them as one promising candidate in lightweight aluminum alloys for elevated-temperature applications.INTRODUCTION Due to the rapid demand from weight-sensitive automotive and aerospace industrials for the light alloys, such as aluminum alloy on the elevated-temperature applications, Al-Mn 3xxx alloys has been developed to obtain the good properties at both room temperature (RT) and elevated temperature, in which the dispersoid-strengthening mechanism plays a significant role (Li & Arnberg, 2003; Li, Muggerud, Olsen & Furu, 2012; Liu & Chen, 2015, 2015). In our previous works (Liu & Chen, 2015, 2015; Liu, Ma & Chen, 2017), the yield strength and creep resistance at 300°C of Al-Mn-Mg 3004 alloy were further improved by modifying the alloying elements, such as Fe and Mo, to optimize the characters of dispersoids, including the size, distribution and the dispersoids free zone (DFZ). For instance, Mo was introduced in aluminum alloy to further improve the volume fraction of dispersoids and reduce the area of DFZ, leading to increasing on both the strength and creep resistance at 300°C (Liu, Ma & Chen, 2017). On the other hand, the mechanical properties became worse at higher Fe content due to its consumption more Mn to form Al6(MnFe) intermetallics, resulting in less available soluted Mn for the precipitation of dispersoids (Liu & Chen, 2015). Therefore, optimizing the characters of dispersoids is always the key to improve the elevated-temperature properties of dispersoid-strengthened aluminum alloys for elevated-temperature applications."

Jan 1, 2017

By Fred A. Webber

STEEL ROPE WIRE is one of the more specialized commodities among the many grades of highcarbon steel wires. In its production there are many metallurgical aspects of interest from the steelmaking on through the final stages of wire drawing. We produce rope wire in an integrated mill com prising all the operations from the blast furnaces to finished wire drawing in the wire mills. Steelmaking is carried out with close control on hot metal, selection of scrap, and fluxing materials. The basic open hearths are of 170 tons capacity. Steel is teemed into 19 1/2 in by 19 1/2 in big-end-down molds and is hot-topped with the use of clay refractory hot-tops. The weight of this ingot is 6,900 pounds. All high -carbon steel ingots are charged hot into the soaking pits and are then rolled through the blooming mill in 16 p asses to a bloom ax~ in. by 41/2 in. and approximately 65 feet long. Necessary bottom and top crops are taken on the bloom as it passes from the blooming? mill to the billet mill. The still hot bloom is continuously rolled through the billet mill in . 5 passes to a 2 3/8 in. square. Billets are cut to 32 feet in length by a flying shear and then allowed to cool on the hot bed.

Jan 1, 1957

By Kurt F. Weitz

"The number of materials that can be classified as fillers covers an extremely wide range: this paper outlines those fillers of the industrial mineral type that find extensive application in the paint and plastics industriesIn the paint industry, mineral fillers are known as extender pigments. Extenders are added to paint and plastic compositions to (1) lower the cost and (2) rein-force or modify the physical properties of a composition.Commonly used extenders are classified according to chemical type and discussed in terms of the change in physical properties that they impart to a paint or plastic film. Available cost reductions and data on the consumption of extenders in the Canadian paint industry are also included."

Jan 1, 1970

By A. Ignatieff

This is the second review of developments in coal mining engineering (see C.I.M .M. Transactions, Vol. LI, 1948, pp. 262- 264) and covers the period from October, 1948, to January, 1950. Mechanization The period under review was characterized by the intensive development of appliances providing for complete mechanization of coal-face operations. A variety of machines are being evolved or have already been placed on the market which embody the principle of 'continuous mining'. This trend can be observed in all coal producing countries. In the United States, two continuous mining machines have been developed for entry and room application and by the end of 1 949 were being used in a number of mines. These are the Joy Continuous Miner in which the coal is ripped from the face by means of multiple cutter chains, and the Jeffrey Colmol employing cutters on rotating arms for chipping the coal from the face. The Joy machine is made in tw6l models, 34-in. and 48-in. high and designed for a range of seam thicknesses from 3-ft. -t-in. to 4-ft. 6-in. and from 4-ft. 6-in. to 8ft., respectively. Some experience has been gained with this machine and accounts of its performance are already appearing in the technical literature. The Jeffrey-Colmol has a more limited range of working height. The first model, 38-in. high, was designed for seams about 4 feet in thick11ess but more recently the 28-in. low model has been placed on the market for seams 2-ft. 6-in, to 3-ft. 4-in. in thickness. Conventional mobile loading machines of the gathering-arm type are continuing to yield high production under suitable conditions, and improvements or modifications of the basic principle are embodied in new machines as, for example, the Jeffrey mobile (conveyor) loader with extensible (gathering-arm) head developed for conveyor mining.

Jan 1, 1950

By F. M. Doyle, G. Sidhu, A. J. Dussault, A. Raygani

There is a growing demand for rare earth metals for use in high strength permanent magnets, most notably Nd2Fe14B. Rare earth metals are extremely reactive, with reduction potentials around -2.5V SHE, and are conventionally produced by molten salt electrolysis. The current work was done to investigate an earlier report of electrodeposition of a neodymium ferroalloy from aqueous solution, to determine whether this approach could be an environmentally and economically competitive commercial approach for producing feedstock for permanent magnets. Such a process would be analogous thermodynamically to the Castner- Kellner process, in which aqueous sodium chloride brine is electrolyzed in cells with mercury cathodes. Metallic sodium forms an alloy (amalgam) at the cathode, thereby lowering the activity of the metallic sodium significantly below unity and making the reduction potential of sodium significantly less negative than the standard reduction potential. Here we report the effects of Nd/Fe ratio in the electrolyte, current density, temperature and two different complexing agents, glycine and cysteine, on the composition and morphology of the electrodeposits, along with current efficiency. The energy needed to produce neodymium as Nd:Fe alloys by aqueous electrodeposition was compared with values estimated for production by molten salt electrolysis and the thermodynamic energy requirement.

Jan 1, 2014

By P. T. O'Kane

The PLATSOL® process, initially developed for the treatment of the NorthMet Cu/Ni/PGM concentrate, has seen over the recent years its applicability extended to include numerous other Cu/Ni concentrates of the same type, as well as other precious metals-containing feedstocks. However, several concentrates were found refractory to the typical PLATSOL® conditions, more particularly so the platinum. Attempts to extend those conditions, such as higher temperatures (250°C), longer retention time, increased oxidation conditions, higher chloride additions, were not successful. Detailed mineralogical investigation of those PLATSOL® leach residues indicated the main refractory mineral to be cooperite (PtS). Further metallurgical investigations showed that a thermal pre-treatment of the concentrate effectively unlocked the refractory platinum minerals for the subsequent leach. Temperatures between 400 and 750°C were tested, with the optimum being found around 650°C. The kinetics of the pre-treatment process were fast, and one hour at temperature proved sufficient. Under those conditions, PLATSOL® extractions were re-established around 95% for both platinum and palladium. From a mineralogical examination of the calcine, it was shown that the effect of the pre-treatment was to transform the cooperite and other refractory sulphides into metallic platinum and alloys, amenable to the PLATSOL®. The implications of the pre¬treatment step for the processing of PGM concentrates arc briefly discussed.

Jan 1, 2004