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By W. Grell

"In this paper, two methods of standardizing mill language are proposed; one is based on metric units and the other on English units. Tentative procedures for chemical and screen analysis based on published methods are proposed.Standard procedures for determining work index, and for leaching, flotation, and classification tests are outlined.Objects of Standardization:(1) to improve communication -(a) among gold metallurgists(b) with other branches of mineral dressing(c) with mineral dressing in other countries(d) with general scientific procedure(2) to improve mill control by -(a) standard methods of analysis (i)(ii)(iii)(b) standard methods of calcula tiort(c) standard accounting proceduresin the plantin the mill laboratoryin the assay office(3) to improve mill test work and investigationAreas of Standardization(1) Nomenclature or terminology(2) Measuring techniques(3) Test procedures(4) Accounting procedures"

Jan 1, 1966

By Roberto Antoniolli

"IntroductionSINCE ancient times, the precious metals have played an important role in influencing the course of history. Silver and gold happened to occur, although in small amounts, in those countries where the early civilizations developed. Their persistent brightness certainly amazed the primitive people, who also found it easy to shape them into ornaments •and implements. Ever since then their properties have made them seem desirable possessions.Use of precious metals as money was the natural consequence of man's desire for them. The possibility of changing an ornament into a tool or food at any time, and the ease with which such medium of exchange could be carried and hidden, further increased the demand for the two metals.Silver was probably discovered after gold and copper, and was undoubtedly found by prehistoric man as native silver. The oldest silver articles have been discovered in Chaldean tombs and date back to 5000 B.C. The earliest ascertained producers of silver were Asia Minor and the Iberian Peninsula. The Romans worked deposits in Spain, Britain, and France. In the Middle Ages, some silver was extracted from German deposits, and near the end of the Middle Ages systematic workings were carried on at Freiberg, Schneeberg, and Joachimsthal (1).Before the discovery of the New Continent, the Aztecs and Toltecs in Mexico, and the Incas in Peru, had made extensive use of silver. In the 16th century the Mexican deposits became the largest source of the world silver."

Jan 1, 1954

By L. Cáceres, G. Leinenweber, P. Bustamante

"Given the severe scarcity of fresh water sources in Northern Chile the use of seawater has become the only alternative to allow mining expansion. This option however poses several technological challenges as a result of the high concentration of natural salts that promote various forms of metal corrosion. Therefore the steel piping protection has been a constant challenge for design engineers responsible for solving the problems of corrosion. Known protection alternatives are varied and expensive, a few of them are rubber coatings, protection based centrifuged concrete, extra wall thickness of pipes in combination with corrosion inhibitors, extra wall thickness of pipes without using corrosion inhibitors, and the use of highly corrosion resistant steel materials.In this framework the aim was to study the corrosion kinetics of carbon steel pipe API 5L X70 under electrochemical and weight loss testing. The test conditions include a range of seawater velocities between 0.2 to 3.0 m/s.For electrochemical experiments the API 5L X70 steel specimen was a 4 mm diameter disk embedded in an 8 mm diameter Teflon rod and exposed to seawater. Duplicated coupons were placed in a standard test apparatus that was built according to the standard ASTM D 2688 – 94.The main results were: a) corrosion mechanism explained in terms of the counterparts partial processes which are the hydrogen evolution and oxygen reduction reaction; b) for the test specimen a corrosion band like feature that suggest a lateral dispersion of aggressive solutions from corrosion pits; c) a range of corrosion rates between 1 and 1.96 mm/year for flow rates between 0.2 and 3.0 m/s; and d) a convenient inhibitor dose between 20–25 mg/L for optimum inhibition efficiency to obtain a maximum value of 80% for corrosion efficiency."

Jan 1, 2016

By B. R. MacKay

Introduction During the past six seasons the writer has been engaged in semi-detailed investigations on the coal areas lying along the front of the Rocky mountains between the Brazeau river and the Smoky River Coal Reserve (see Map, Figure 1). The purpose of this paper is to present some observations pertaining to the stratigraphy and structure of the district, touching especially upon the lithological units into which the Lower Cretaceous sediments have been divided, the thicknesses of the formations at different localities, the number, thicknesses and horizons of the principal coal seams, and the structural conditions which exist in the various fields.

Jan 1, 1930

By M. J. Fairweather

"The development of means to maximize the selectivity between galena and sphalerite in lead zinc ores is extremely important to the lead-zinc industry. Two challenging studies recently undertaken by Cominco will be reviewed. The first required an unusually fine grind to achieve liberation between galena and sphalerite. The second contained partially altered galena which resulted in unusual early activation of sphalerite under normal flotation conditions. Means by which lead and zinc separation were optimized in these two ores will be discussed.There are two important factors in the separation of minerals by froth flotation: particle size distribution (grind) and pulp chemistry. Pulp chemistry includes a number of factors including pH, Eh, collector type and concentration, inorganic depressants, organic depressants and activators.Grind is important for two reasons. A sufficiently fine grind is required to optimize liberation. However, if the mineral dissemination is too fine, mineral selectivity in the flotation process is impaired. Due to the hydrodynamic constraints of conventional mechanical flotation cells, flotation works best over the single decade size range between 10 and 100 microns. The majority of new ores treated by Cominco until relatively recently were comparatively simple. The major factor in their treatment was defining optimum grind size. Accordingly, the focus within mineral processing at Cominco was on grind and supporting liberation studies. The relationships between grind, liberation and flotation response are intuitively easy to understand. An idealized relationship is shown in the first figure."

Jan 1, 1991

By N. Musee, N. Kornelius

This study presents a neural network approach to modelling the liberation of gold bearing ores. A complete mineralogical analysis of unmilled and milled ores, including gold deportment and gangue content are used as inputs to a self-organising neural net which generates order preserving topological maps. The arrangement and shapes of these clusters are coupled to unmilled free gold data to predict gold liberation in milled ores (absolute error: 4.2%). Moreover, the self-organising maps were diagnostic of the quality of data used, indicating that the relationship between particle size and gangue material content requires further investigation.

Jan 1, 2005

By Kym Runge, Emmy Manlapig

"The objective of an industrial flotation circuit is to separate valuable minerals from non-valuable minerals utilising differences in their flotation recovery rate. Regrinding and reagent addition are particle modification processes which are employed within these circuits to maximise the flotation selectivity of one mineral with respect to the others present in the ore feeding the process.Batch test nodal analysis, or the ability to compare floatability through mathematical combination of laboratory batch flotation test results, is a powerful technique for assessing the effectiveness of particle modification processes on ore floatability in industrial flotation circuits.In this paper, the use of nodal analysis is demonstrated within an industrial flotation circuit. It is used to show that regrinding and staged reagent addition within Teck Cominco’s Red Dog zinc retreatment circuit is beneficial to pulp flotation selectivity. Optimisation of these processes could potentially improve the zinc recovery within the circuit. Lime addition, which is periodically employed to depress pyrite in the circuit, was found to depress sphalerite in preference to pyrite and to result in poorer metallurgical performance in the circuit.INTRODUCTIONThe objective of an industrial flotation circuit is to separate valuable minerals from non-valuable minerals utilising differences in their flotation recovery rate.Different minerals can only be effectively separated using flotation if they are sufficiently liberated from each other (i.e. do not co-exist within the same particles) and have a sufficient difference in surface hydrophobicity. Size reduction processes and chemical addition are utilised before and within a flotation circuit to achieve sufficient particle liberation and to maximise differences in mineral hydrophobicity. In effect, the objective of these processes is to maximise the flotation selectivity of one mineral with respect to the others present in the ore feeding the process."

Jan 1, 2004

By John S. Stevenson

"Although we have no uranium- producing mines as yet in British Columbia, uranium, associated with gold and cobalt, has been found in two deposits in amounts such that the combined value of the metals not only warrants the further exploration of these deposits, but also encourages the search elsewhere in the Province for other similar deposits.Where uranium-bearing veins have been found in British Columbia, the uranium mineral is the crystalline variety of uranium oxide, uraninite, rather than the massive, non-crystalline variety, pitchblende, such as found in the Great Bear Lake deposit and in other similar deposits along the southwestern margin of the Precambrian shield.The principal occurrences of uranium known so far in British Columbia are associated with bodies of granodiorite and quartz diorite along the eastern side of the Coast Range belt of batholiths. In this part of the Province, interesting amounts of uranium occur on the Gem property in the Bridge River area and on the Victoria property south of Hazelton; and smaller amounts occur on the Red Rose, Rocher Debouze, Delta, and Ohio properties, also south of Hazelton. At the Gem and the Victoria, the uranium mineral, identified as uraninite, occurs in deposits that also contain abundant cobalt-nickel sulpharsenides, and molybdenite.At these properties, the uraninite occurs as clusters of small black crystals of sub-metallic lustre that may be seen upon careful -searching of a highly radioactive specimen with a hand lens. Under the microscope, the uraninite is seen to be in the form of cubes or modifications of cubes that may occur as individual grains widely scattered throughout the gangue or may be gathered into clusters of several grains. The grain size of the uraninite is in general small. Although a few clusters of grains are up to about 10 mesh in diameter, the individual grains, whether in clusters or widely disseminated, are rarely more than 400 mesh in diameter."

Jan 1, 1950

By Craig M. Sams

"Variable speed mill popularity has grown during the last 10 years with almost every SAG mill fitted with a variable speed drive. In addition, many of today’s larger ball mills are running a variable speed drive for various reasons. In the past, motor suppliers, especially gearless drive suppliers, have considered mills as being an overpriced rotor. This has lead to mills demanding more torque than what a motor can generate. This paper identifies the reasoning of what has happened and how to mitigate the mismatch in the future. Technical and economical issues are discussed, allowing mill operators to make an informed decision of which path to take in deciding what motor to put on a mill.INTRODUCTIONIt has been generally accepted in the past that motor suppliers and specialists in engineering companies understand the workings of a SAG mill or a ball mill and although there is a fair knowledge within the industry, in regards to mill torque requirements, the advent of variable speed drives in ball mills has shown the writer that a complete understanding of the mill torque requirements are not fully understood.This paper will discuss two aspects of mill torque requirements, (operating torque at various charge levels and start up torque), and how it relates to specifying the proper motor torque requirements.MILL OPERATING TORQUEMill operating torque at a given charge level and density in a mill is essentially constant throughout the entire speed range. For the purpose of this paper, we will take a 38’x 22.5’, 20’ EGL, SAG mill and provide the power draw at variable speeds but fixed loading conditions.The power draw and mill torque of this mill at 8% ball charge and 28% total loading (Highlighted) is shown below as Figure 1, at variable speeds."

Jan 1, 2007

By Tong Guan, Guangqin Fu, Lihong Deng, Yuanlin Chen, Xiaotong Zhou

"In natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the content of MoO3 varies from 2% to 10%. As a result, the flotability of seyrigite (scheelite with molybdenum) turns to be weaker. One seyrigite mine, which has been built for 3 years,still could not produce qualified seyrigite concentrate due to the weak flotability of seyrigite (Mo-bearing scheelite) in raw ore. In our experimental research, through adopting new seyrigite collector TA-3 and advanced mineral processing technology, the seyrigite concentrate with a grade of 65.62% WO3 at a recovery of 87.47% was obtained for the raw ore containing 0.19% WO3 and 0.074% Mo. By applying the new technical achievement, for the raw ore containing 0.272% WO3, the seyrigite concentrate assaying 68.03% WO3 with a recovery of 77.56% was obtained in industrial production.INTRODUCTIONIn natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the scheelite is changed to be seyrigite (Ca[(W,Mo)O4]) (Ma, Bian, & Wang, 2013). The content of MoO3 in seyrigite varies from 2% to 10% usually, the content of MoO3 in some of the seyrigite even reaches 34%. The flotability of seyrigite is weak (Zhang, 2007), and the seyrigite is difficult to be recovered by flotation with common collectors and regulators. One scheelite mine in Anhui China, which is a skarn type seyrigite mine, has not produced qualified concentrate yet since 3 years it has been built due to the limit of beneficiation technology. Therefore, it is necessary to conduct research on the collectors with high efficiency and developing advanced processing flow for this kind of ore."

Jan 1, 2016

By E. G. Langille

"The Premier mine; owned by Silbak Premier Mines; Limited; is 14 miles from Stewart at the head of Portland canal. Development of the property began in 1918; and since chat time a very large amount of gold and silver as well as some lead and copper have been produced from the mine.The area in the vicinity of the mine is underlain by greenstones tuffs, and sediments of Mesozoic age, belonging to the Bear River formation of the Hazelton group. These rocks are intruded by a stock 2 miles in diameter, composed of orthoclase porphyry and called the Premier porphyry. It sends numerous sill-like and dyke-like tongues into the Bear River formation, and is intruded in turn by a granodiorite outlier of the Coast Range batholith. The orebodies occupy fractures and fracture or shear zones. Primary ore consists chiefly of pyrite, galena, and sphalerite, with some chalcopyrite. The upper 300 feet, or locally 600 feet, contained presumably secondary silver minerals."

Jan 1, 1954

By D. J. MacKinnon

Zinc metal was first produced in India around 1100 A.O. and a zinc industry based on retorting gradually developed in both India and China(1) . The vertical retort method for smelting zinc ores was developed in England in the 1730s; this was followed by the more fuel efficient horizontal retort process developed by the Belgians in the 19th century(2) . The horizontal retort process was the standard method of zinc manufacture until the 1950s when it became obvious that it could not compete with electrolytic zinc technology(2). The present day extractive metallurgy of zinc is dominated by the electrolytic process which now accounts for almost 80% of the world's primary zinc production. In recent years the electrolytic zinc process has seen significant improvements: the fluid-bed roasting of zinc concentrates, improved leaching and residue treatment techniques such as the jarosite and goethite processes, improved solution purification procedures, mechanization of the zinc electrolysis step and of the zinc melting and casting operation. In addition, new leaching processes have been implemented for the treatment of oxidized ores, particularly silicates, and the pressure leaching of zinc sulphide concentrates is now a commercial reality. Although the electrolytic zinc process was first used on a commercial scale in 1916, its history can be traced back to the 1860s. The purpose of the present paper is to outline the early history of the electrolytic zinc process and to trace the significant developments which led to the first successful commercial electrolytic zinc plants.

Jan 1, 1999

By Esau Arinaitwe

The most extensively used methods and approaches for characterizing and selecting frothers for plant application are based on measurements in clean water in the absence of solids and without consideration of physicochemical factors that are known to influence the properties and behavior of practical flotation froths, and hence metallurgical performance. These factors include aquatic chemistry, collectors, modifiers, particle shape and size, and pH. Understanding interactions between these factors and the role and relevance that they play in characterizing frothers and froth zone properties will greatly aid in the frother selection and evaluation process. Such an understanding will also greatly enhance the ability to create frother solutions that are sufficiently robust to plant variability (such as mineralogical, comminution, operational, physical and chemical). This paper reports results of a “systems approach” study designed to probe ways in which physicochemical factors a) influence frothing and bubble size in 2- and 3-phase systems, and b) confound correlation of fundamental measurements with flotation outcome. The concepts and insights gleaned from fundamental frother studies, together with empirical laboratory flotation tests and a thorough understanding of plant needs and challenges were used to develop and implement customized frother formulation at a Cu-Mo flotation plant. Plant metallurgical data and qualitative assessment of froth zone properties showed that a frother formulation developed using the approach described here provided marked improvements in froth characteristics (mineralization, mobility, stability, persistence). These improvements resulted in better circuit control and significant performance advantages, such as improved coarse particle recovery, without detrimental downstream effects. INTRODUCTION Successful recovery of value minerals of sufficient grade via the flotation process requires selective manipulation of the value minerals to render them hydrophobic using collectors and modifiers. The hydrophobized minerals then attach to air bubbles and the mineral-bubble aggregates are selectively transported through the froth zone into the launder. Frothers play a critical role in froth formation and more importantly in achieving and maintaining desirable froth characteristics (for example, stability, mobility, persistence) that are essential in facilitating the selective transport and recovery of value minerals. Fundamentally, frothers contribute to the transient stability of thin liquid films and so aid in reducing bubble coalescence rates in the pulp and froth zones, thus maintaining the small bubbles required for efficient bubble-particle attachment. Invariably, the action of frothers at the liquid/gas interface in the pulp and froth zones impacts bubble stability, water and solids transport to the froth, which in turn impacts froth mobility, froth carrying capacity, and the concentrate grade. Consequently, selection and evaluation of frothers for flotation plants requires careful consideration of the frother type, though the choice is limited to only two main classes of compounds in terms of fundamental chemistry (short chain alcohols and polyglycols). Even with the selection of what is thought to be the best frother for a given application, practical knowledge of the froth zone and experience in controlling its properties is essential for maximizing metallurgical performance.

Jan 1, 2019

By F. A. Charalambous

Brannerite is commonly referred to as a refractory uranium mineral as it is usually highly resistant to acid leaching. There is however widely varying literature data on brannerite leaching, with some studies reporting that brannerite leaching can be achieved under relatively mild conditions. The differences observed for brannerite leaching are most likely due to the high degree of variation in the composition and structure observed in natural brannerites. These aspects of brannerite chemistry however are not very well understood due to a lack of fundamental research. The aims of this study were to investigate and develop methods for synthesising brannerites of varying composition and to investigate the effects of composition on brannerite leaching in acidic conditions.

Aug 1, 2010

By G. G. Richards, Y. Oyediran, V. Chow

The oxygen softening process for partial removal of arsenic and antimony from lead bullion has been in use at Teck Cominco's Trail smelter since 1986. In this process, industrial oxygen is injected into bullion to remove As and Sb with the formation of an oxide slag. In Trail, the levels of these elements are reduced to concentrations suitable for processing in the Betts electrorefining plant. Recent moves toward the treatment of higher arsenic-bearing feeds have necessitated an increase in the process capacity to meet the specifications for drossing plant bullion. Process intensification trials were conducted in-plant to develop an operating strategy for higher bullion processing rates. This was preceded by a study conducted with McGill University to develop a fundamental understanding of the therm ochemistry and kinetics of the process. The results have yielded more effective control of the operation, and identified opportunities for further improvements.

Jan 1, 2008

By A. M. Martinez, L. Melis, R. C. Peláez, L. G. Garcia

Orovalle Minerals S. L. operates a copper/gold mine in the Asturias region of northern Spain, with the operation dating back to December 1997. The feed to the El Valle mill, consisting of oxide/sulphide (skarn) mineralization, is highly variable, even on a shift by shift basis and presents challenges to the mill operating staff on a daily basis. The mineralogical characteristics of the ore are quite complex with copper present as native copper and sulphides as well as copper minerals with deleterious elements. Gold is present as native gold and electrum. The mill circuit includes SAG/ball mill grinding, gravity recovery of native copper and gold, flotation of copper concentrate, carbon-in-leach gold recovery and SO2/air cyanide destruction. The paper will provide a description of the different unit operations and present operating data of the mill operation.

Jan 1, 2019

By Martin Murenbeeld

Outlook: Nine Bullish Arguments 1. Global fiscal and monetary reflation: PIIGS, US, etc. 2. Global imbalances: the dollar must decline 3. Global FX reserves are ?excessive?: diversification 4. Central bank attitudes to gold: now positive 5. Gold is not in a bubble: room to rise 6. Mine supply is flat: ?peak? gold? 7. Investment demand: long-run uptrend 8. Commodity price cycle: many years to run 9. Geopolitical environment: positive

May 1, 2010

By K. Nikkhah, N. Dhadli, G. Freeman

Ammoniacal pressure leaching operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation since 1954. Recent improvements have significantly increased the capacity of this circuit. The computer modeling of this process has proved to be a valuable tool in facilitating the evaluation of different operating scenarios in an effective manner. Reagent response in the ammonia leach of nickel and cobalt sulphides is examined using the dynamic process simulation capabilities of IDEAS(TM) software. The dynamic simulation enables accurate measurement of the sensitivity of the process to variables such as temperature, feed rate and ammonia concentration as well as compartmental analysis of metals concentration, pulp density, vent gas composition, and the formation of specific complexes. The complexity of the ammonia leach process makes it a logical choice for evaluation by computational analysis. The methodology for dynamic modeling of a pressure leach process is presented.

Jan 1, 2005

By M. Lahtinen

Traditionally, there have been three main methods for iron removal in the hydrometallurgical production of zinc. These methods are atmospheric precipitation of jarosite or goethite and pressurised precipitation of hematite. Jarosite precipitation is without doubt the leading and the most commonly used technology for iron removal. However, jarosite precipitation has some drawbacks, such as a low iron content (and, thus, high residue volume), high moisture content after filtration and often a high zinc content. These features make any environmentally acceptable way of using or disposing of jarosite more expensive, as compared to hematite and goethite. The importance of environmental regulations has grown in the zinc industry during the last decade, which will have an increasing effect on new investments. Hematite has several advantages over jarosite, such as a high iron content, low moisture and low zinc content. An important advantage of hematite is that it is suited for further use in the cement industry. However, until now the need for autoclave equipment has limited the spread and implementation of hematite precipitation in the zinc industry. Outokumpu Technology Oy has recently developed an alternative method for iron removal, which is the atmospheric precipitation of hematite. A patented method for precipitating hematite at atmospheric pressure is presented and compared with conventional methods for iron removal. The process conditions, the quality of the hematite precipitate and the environmental aspects are also discussed.

Jan 1, 2006

By Patrick J. Williams, Peter J. Pollard

"Abstract - Enigmatic hydrothermal vein/breccia/replacement Cu-Au deposits with magnetite and/or hematite are well-represented in Australian 1850 Ma to 1500 Ma terrains and associated with different-aged synorogenic intrusions in the Tennant Creek Block (ca. 1850 Ma); the Gawler-Curnamona region (1640 Ma to 1590 Ma); and the Cloncurry district (Mount Isa Eastern Fold Belt, 1540 Ma to 1500 Ma with a possible earlier event at ca. 1600 Ma). No deposits are known to be coeval with various 1780 Ma to 1610 Ma anorogenic intrusions. Deposits are hosted by many different rock-types with varying metamorphic grade including granites and various supracrustal rocks. Depth of mineralization varied from many kilometers in semiductile crust (e.g., Cloncurry deposits) to very shallow (e.g., Olympic Dam). Ore deposition near Cloncurry occurred in brittle-ductile shear zones from geochemically variable and complex, CO2-rich, 300°C to 500°C, high salinity fluids with magmatic stable isotopic signatures. Recently published studies of a giant granitoid-hosted magnetite vein complex at the Lightning Creek prospect (>1000 Mt magnetite) suggest it is a product of internal differentiation and endogenous Fe and Cu-rich hydrous-carbonic fluid phase generation within a quartz monzodiorite-monzogranite intrusion. Coupled with other field relationships, this points to a possible genetic relationship with intermediate (55 to 65 wt% SiO2) members of an alkaline and partly shoshonitic granitoid supersuite which appears to have both mantle and crustal source components from ?Nd evidence. In constrast, main-phase mineralization at Olympic Dam in the Gawler Craton is distinguished by hematite-phyllosilicate alteration and chalcopyrite-bornite-chalcocite zoning, reflecting fluid mixing in a high level (<250°C) system with a probable large component of meteoric water. Early high-temperature parageneses and fluid inclusions imply that the extensive hematitic breccias overprinted an older magnetite system which may have had similarities with those at Lightning Creek and Ernest Henry in the Cloncurry district.Deposits of this family are inherently difficult to find and evaluate as even within a single district, there is no reliable relationship between the location of ore and any specific combination of geophysical characteristics. Diverse alteration assemblages, geochemistry and physical characteristics suggest the deposits reflect the interaction of multi-sourced fluids with different host rocks in a wide range of geological environments. Recent discoveries and research in the Cloncurry district have extended the range of deposit models available and aid the development of a rudimentary classification in which economic and exploration characteristics can be linked to variations in the mechanisms and environments of ore formation."

Jan 1, 2001