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By N. Dave

"IntroductionIn the mineral processing industry, certain minerals such as uranium, thorium and vanadium, etc., are selectively extracted with high degree of purity from solutions containing variety of other impurities by solvent extraction process. This separation process consists of bringing two immiscible or partially soluble liquid phases in contact, where mass transfer of one or more components takes place by ion exchange under certain controlling parameters such as pH, salt concentration and temperature. The processes taking place are primarily physical because the solutes being transferred are ordinarily recovered without chemical change. For efficient extraction more than one stage is required and the solutions are recycled counter currently through other stages. A multi-stage counter current solvent extraction plants essentially consist of four circuits namely: extraction, water wash, stripping, and solvent scrubbing. In extraction circuit the desired mineral is extracted at a certain pH from an aqueous solution onto an organic solvent by bringing them in contact with mixing in large mixer-settler units. The mixed solutions are allowed to settle and separate into component organic and aqueous phases in horizontal settlers by providing sufficient residence time. The solutions are then moved counter currently to other units- the aqueous from the underflow and the solvent organics from the overflow of the settler. The solution streams coming out of extraction circuit are loaded organics and barren aqueous or raffinate solution. The loaded organics are washed with water in a water wash circuit to remove transported impurities from extraction circuit. In the stripping circuit, the desired mineral is stripped selectively from the solvent phase back into an aqueous phase with a stripping agent at a selected pH. The solution stream leaving, stripping circuit are stripped organics and pregnant strip (aqueous) solution. The stripped organics are scrubbed off other loaded impurities with a conditioning solution in, scrubbing circuit and the cleaned solvent is re-used in the extraction circuit.A typical solvent extraction plant for uranium extraction and purification at Agnew Lake Mine is described in this chapter."

Jan 1, 1989

By D. A. Mackie, J. E. Rider

"Good belt conveyor design is the most often neglected detail in the engineering of a plant. This results in downtime from spills or jams and premature failure of equipment components. Careful layout and component selection will result in better operation, a cleaner plant and therefore lower maintenance costs.IntroductionDespite the availability of many excellent sources of data on conveyor design, such as the Conveyor Equipment Manufacturers' Association (CEMA) Manual, ""Belt Convyors for Bulk Materials"" , there continues to be repetitive errors made in design. Why? Certainly, there is no substitute for experience, but largely, classical errors in belt conveyor design is rather elementary and so the temptation to have the work done by relatively inexperienced designers is great. What that does is develop "" experienced"" designers who become incompetent through no fault of their own. It is hoped that this paper will supplement available design data, help those who are "" put into"" a design situation to better cope with their predicament, and ease the lives of plant maintenance personnel."

Jan 1, 1990

By R. E. Whitehead

"The earliest gold-mining operations in Ontario included the Cordova, Deloro, and Sophia mines north of Lake Ontario (see for example, Miller and Knight, 1914). The Cordova deposit, worked intermittently between 1891 and 1940, is reported to have yielded 22 774 oz of gold from 127 670 tons of ore averaging 0.19 oz/ton Au (Gordon et al., 1979). The property remained inactive for many years. In 1988, Gunnar Gold Inc. and Mill City Gold Inc. conducted a drilling program along the main Cordova vein. The present study is based on core from three drill holes through the Cordova gabbro (Fig. 1) and the carbonate alteration zones enveloping the quartz-carbonate veins. The relatively narrow width of the alteration zone and the availability of continuous sections of core provided an opportunity to conduct a compact mineralogical-chemical study of carbonate alteration and its effect on the redistribution of rare earth elements (REEs). Although the Cordova deposit is not of great economic importance, this study has revealed a number of interesting features which are interpreted as resulting from processes that may be applicable to gold-bearing quartz vein deposits elsewhere.The Cordova gabbro is layered in places, varying from fine-to coarse-grained and in color from light gray (feldspathic) to dark gray-green (amphibolitic). However, layering within the section of the gabbro considered here and which hosts the Cordova gold deposit is mainly textural rather than compositional. Samples of unaltered gabbro selected for analyses were medium- to coarse-grained; amphibolitic and anorthositic phases were avoided as being less representative of the general chemical composition of the gabbro.The Cordova intrusion has undergone regional metamorphism and consists dominantly of actinolite and saussuritized plagioclase with smaller amounts of granular clinozoisite and flaky chlorite; minor quartz, ilmenite, titanite, apatite, and calcite are typically present. Some actinolite grains have irregular rims of pleochroic green hornblende that is optically continuous with the actinolite. Both chlorite and clinozoisite occur in two modes. Chlorite occurs as an alteration product of actinolite and as separate grains in the groundmass. Clinozoisite and albite occur together as regional metamorphic alteration products of original plagioclase crystals and as discrete grains in the matrix.The main gold-bearing quartz-carbonate occurrence occupies an easterly trending, steeply southward-dipping carbonatized shear zone up to 15 m wide and 700 m long. The gold occurs principally in irregular lenses and veins of quartz-carbonate up to a foot thick occupying the lower part of the schistose shear zone within the gabbro. This zone consists of chlorite, biotite, and carbonate and is flanked on both sides by chlorite-carbonate schist lacking biotite. The chlorite-carbonate schist in turn grades into regionally metamorphosed actinolite-bearing undeformed gabbro.The dominant sulfide within the quartz-carbonate lenses and in the surrounding schist is pyrite which occurs mainly as small cubes (1 mm to 2 mm) generally making up less than 10% of the rock. Rare blebs of chalcopyrite are present. Magnetite is common throughout the schist."

Jan 1, 2001

By S. Nakamura, K. Fujiwara, S. Hirosawa, S. Tsukamoto, Y. Koshino, Y. Aruga

"In this study, hardness test, differential scanning calorimetry(DSC)and transmission electron micros copy were carried out to investigate the age-hardening behavior of Al-Mg-Si alloy with a Mg+Si concentration of 1.5mass%, and a Mg/Si ratio of 1.0. Pre-aging treatment was conducted for the solution-treated and then water-quenched specimen at 100, 80, 60, 40, 20 (natural aging), 0 and -20°C for 20min or 5h, followed by artificial aging at 170°C for 20min. It was found that when pre-aging time is prolonged from 20min to 5h, the bake-hardening response is deteriorated irrespective of the pre-aging temperature. In particular, the specimens subjected to pre-aging at 20-40°C for 5 h hardly increased the hardness with the subsequent artificial aging. From the results of DSC measurement, it was suggested that as pre-aging temperature is lowered, the amount of solute clusters formed during pre-aging, i.e. Mg-Si clusters and Si-rich clusters, is decreased, but the ratio of Si-rich clusters is increased, resulting in the deteriorated bake-hardening response.INTRODUCTIONIn recent years, Al-Mg-Si alloys have been widely used forautomotive body panels due to their excellent characteristics such as high strength-to-weight ratio and good formability. Their strength is increased not only by artificial aging during paint-bake treatment; i.e. “bake-hardening”, but also when kept at room temperature(RT);i.e. “natural aging”, in association with the suppressed bake-hardening response. Such a “negative effect of two-step aging” has been a serious problem because Al-Mg-Si alloy coils are unavoidably maintained at RT in the manufacturing process of body panels; e.g. shipping and storage. However, it was reported that pre-aging above 70°C before the two-step aging can restore the bake-hardening response, and such an improvement is related to the formation of solute clusters(Sato, 2006; Abidet al., 2010; Takaki et al., 2014; Zandbergen et al., 2015). From the comprehensive analysis by three-dimensional atom probe (Aruga et al., 2014 and 2015), it is believed that Mg-Si clusters formed during pre-aging transform into the strengtheningß"" phase, whereas Si-rich clusters formed during pre-aging act as a detrimental precursor of ß""phase. In this study, it was aimed to investigate the effect of pre-aging conditions, especially pre-aging temperature and time, on the formation of solute clusters during pre-aging, in order to elucidate the mechanism of the age-hardening behavior of an Al-Mg-Si alloy."

Jan 1, 2018

By Guillermo Diaz, Roberto Pérez, René del Villar

"Pulp-froth interface position is a key variable in column operation. In plant practice, it is commonly estimated through a system of three pressure-transducers which allows the calculation of the pulp height. An alternate method based on the measurement of the conductivity profile across the interface has been proposed and successfully tested. Both methods however, present some practical problems related to the assumptions made in the calculation of the pulp height in the former case, and to the response time and the precision of the reading in the latter case.In this paper, the use of the neural network technique for improving the estimation of the pulp-froth interface in flotation columns is discussed. The technique is used with both conductivity-based and three pressure-transducer methods. Results obtained in a 2"" laboratory column and a 12"" pilot scale column are presented. A major obstacle in applying this approach in practise is the training of the artificial neural network. This problem is analyzed here for the conductivity-based method and some solutions are proposed."

Jan 1, 1995

By M. Leijd, K. S. Forrester, M. Saxon, M. Oczlon

This paper provides an introduction to wet high intensity magnetic separation (WHIMS) and its successful application to the beneficiation of rare earth element (REE) enriched eudialyte. The analysis includes an in-depth reporting of the deportment of key elements as well as a statistical interpretation of the relative importance of operational parameters including magnetic field intensity, flow velocity, and matrix loading density. Conclusions are drawn on the relative success of the technology, potential areas for process improvement, and the research direction that continues to be investigated. Three original equipment manufacturer (OEM) technologies were subjected to a series of screening and characterization tests to identify the optimal operating parameter set to magnetically beneficiate eudialyte from Norra Kärr, Sweden. Upon the completion of the characterization test it was apparent that the Metso HGMS technology was superior with respect to REE recovery and gangue rejection for the Norra Kärr composite. The Metso HGMS was then subjected to a series of verification tests to confirm the repeatability and reproducibility of the system.

Jan 1, 2014

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015

By G. J. Hawkes

"We all know that every man who works for us should have a thorough knowledge and understanding of his responsibilities. But how about ourselves? Du we have a thorough knowledge and understanding of our own responsibilities as Mill Superintendents?I once had an occasion to say to a Manager that I did not know something was my responsibility and he replied with suitable emphasis ""Everything inside those four walls is your responsibility"". That makes the extent of our responsibilities clear but does not give us a check list to keep an eye on as we do our job from day to day.What are our responsibilities? I suggest they are the following:1. Developing and maintaining efficient operating and maintenance crews.2. Milling the required tonnage.3. Recovering the economical maximum amount of gold.4. Keeping costs at the economical minimum.5. Seeing that the figures are reasonably accurate for tonnages, assays, production, losses, and costs.6. Preventing accidents.7. Preventing fires.8. Maintaining the equipment and building and keeping them clean and tidy.9. Enforcing company rules and regulations."

Jan 1, 1965

By Forrest A. Kerr

Northern British Columbia is a term which probably conveys to various individuals quite different meanings. To the average person it signifies an area of indefinite size and indefinite position which may start at Prince Rupert, Stewart, or somewhere else, and end at Alaska or .the Yukon. Many people, in their conception, fail to encompass in their mind's eye that vast tract of land lying ~o the east of the panhandle of Alaska. Few realize that the area north of an east-west line through Stewart represents more than one-third of the Province and is, of course, the part most appropriately designated as northern British Columbia. This section, more especially the northernmost 100,000 square miles, from political, geographic, and economic viewpoints stands isolated perhaps more than any other part of British Columbia. Unlike the rest of the Province, it has no coast line, being cut off from the Pacific ocean by a narrow strip of Alaska. It is bounded on the north by the Yukon, and on the east by Alberta. In the south this northernmost 100,000 square miles is limited by a divide of rugged mountainous country separating the drainage basins of the Stikine and Liard rivers from those to the south.

Jan 1, 1929

By Paul J. Beck

The impact of mining development on the environment can be minimized through comp careful construction and accurate monitoring. Key to meeting these objectives is t information at all stages of design, development, operation and decommissioning. This paper will describe cost-effective means of gathering and managing reliable fiel groundwater flow and surface water regime within and surrounding the mine site, as localized contaminant plumes associated with mine operations, and monitoring ground quality. Recent research has led to the development of inexpensive, easy to install syst sampling/monitoring from different zones within a single borehole. Advances in elect developed small diameter probes and pumps for measuring water levels and taking wat continuous monitoring stations in remote areas can be colldeacttaeldo gaguetrosm aatnidc adlolwyn luosaidnegd from a central facility using telemetry systems powered by direct, battery or solar radio frequency, landline or cellular telephones, and satellite. Two case studies will illustrate the use of datalolgagregres sacnadl et eblaesmient rwyi dien mao nitoring sc and the use of multilevel samplers for managing a contaminant plume.

May 1, 2004

By A. Zangooi, J. A. Finch

Flotation is a separation process based on the collection of particles on the surface of bubbles. Flotation machines disperse air into bubbles using a variety of techniques. The characteristics of the bubble population are strongly affected by the selection of frother type and concentration. As metallurgical results depend on the bubble distribution, the measurement of frother concentration is vital to understand and control performance. A previously developed colorimetric technique was refined to work with low solubility frothers and to increase daily analysis rate. Field-testing demonstrated that the method is robust, reliable and accurate. As well as relating frother concentration to gas dispersion measurements, the results can be used to answer operational questions including: how well a frother dissolves, how reliable and stable frother delivery is, how evenly frother is distributed down a bank, and whether frother distributes between the pulp and froth zones. Some of these points are illustrated from plant experiences. Advances in Mineral Processing Science and Technology Proceedings of the 48th Annual Conference of Metallurgists ofCIM Sudbury, Ontario, Canada Edited by

Jan 1, 2009

By I. Pérez-Rey, J. Arzúa, L. R. Alejano

"The decrease in strength with increasing rock specimen size is usually associated to the increase in the number of defects inside the specimens at small scale (centimeters) but also to the role of the rock mass structure at the rock mass scale (meters to decimeters).This matter of concern was particularly focused when determining the size of pillars in underground mines. Some formulae regarding strength of pillars have been proposed but they usually consider only the size and shape of the pillars and the strength of the intact rock. The structure tends to be overlooked or hidden behind the scale, but it is probably very relevant. For standard tunnel design, the approach by Hoek and Brown (1997), taking the structure into account in terms of the GSI, is commonly used. However, this approach does not specifically consider the size of the tunnel. Thus, a size larger than the so-called representative elementary volume is implicitly contemplated.The authors have recently performed a lab study on the effect of the structure in the strength, deformability and post-failure characteristics of granite at lab scale (NX size) extended here. This experimental program included intact and artificially jointed rock specimens. Obtained results permit to observe the changes in strength, deformability and post-failure behavior of this “small scale rock masses”, associating the role of the structure to the observed complete stress-strain response of the specimen, which can improve our understanding of the actual complete mechanical response of rock masses."

Jan 1, 2015

By S. Borle

The microstructural features produced in friction stir welded AZ31, AZ80 and AZ91 alloys are examined when different welding parameters are applied. The microstructures primarily consist of a-Mg grains with a-Mg + Mg17A112 colonies, however melted films of Mg17A112 are produced in AZ91 alloy when high rotation speeds are applied. When the rotation speeds are slow, or the travel speeds are fast the Mg17A112 were incorporated into the stir zone, however they do not exhibit an elongated lamellar morphology associated with melted films. In the case of AZ80, the extruded base material contains a smaller fraction of Mg17A112 and few of these phases are observed in the stir zones. The results are explained based on the dissolution rate and melting temperatures of Mg17A112 controlling the overall morophology and fraction of phases in the stir zone.

Jan 1, 2011

By G. Simard, D. Boudeville, A. Leclerc, A. Boivin

"The objective of this work is to study the various parameters that affect the overflow clarity of gravity settlers used in the precipitation circuit of alumina hydrate from the Bayer process. A mathematical model incorporating the size distribution of the feed suspension (Multi Size Group model), its diphasic nature (Schiller Naumann model) and the presence of turbulence (Shear Stress Transport model) has been solved numerically using ANSYS-CFX software. Preliminary results indicate that the overflow clarity is mainly controlled by lateral diffusion of fine particles (~20µm) from the exit of the feed well and by their upward transport from the sediment bed interface. Also the turbulence pattern in the settling zone seems to play a significant role in this vertical transportation. The validity of the model has been verified by comparing the measured solid concentrations from a pilot classifier with the calculated ones. This model could provide mineral processing plant operators and designers with a tool to optimize the configuration of classifiers with respect to the overflow clarity.INTRODUCTIONProblemIn the Bayer process, alumina hydrate precipitation from the saturated liquor is initiated in settler by adding crystallization seeds. Most of the precipitated alumina settles to the bottom of the tank while the liquor and the remaining alumina rise to the top, where they are removed at the overflow. Ideally the overflow clarity, which depends on the operational mode of the classifier, should be controlled within targeted limits."

Jan 1, 2016

By J. I. Jr. Moore

Many articles have been written about the various operations of Britannia mines and mill, as well as treatises on the geology and ore deposits. A partial list of these papers is given below. Most of these papers have covered well the history of Britannia, and have included a thorough discussion of the geology and ore deposits; therefore, in this paper, no account of these subjects. is necessary. However, a short description of the ore deposits will be given as an aid to a clear understanding of the descriptions of the various mining methods. The Ore Deposits The ore deposits at Britannia occur along a shear zone and are five in number, named for the claims in which they lie, as follows: Jane, Bluff, Fairview, Empress, and Victoria. Each of these deposits is called a mine, as they are separated by 500 to 1,000 feet of barren ground. The Jane mine, although the first producer of the Britannia group, has not been in operation for a number of years. The deposit is a silicified replacement in sediments; with very little evidence of shearing. The Bluff deposit is a highly silicified replacement in porphyry, massive and irregular, very hard in the upper 600 feet with practically no shearing, and softer within chlorite schist in its lower 1,000 feet . The Fairview deposit consists of a series of twelve distinct veins or lodes, rather lenticular in shape, and occasionally merging.

Jan 1, 1928

By Gheorghe Vieru

Security and safety due to environmental impact as well as the radiological consequences during the uranium mining operations, tailings management, uranium processing, disposal of waste in conventional landfill sites are matters of great importance. The Uranium National Company (CNU) from Romania is responsible for all aspects belonging to the management of the entire Romanian uranium industry- the uranium ore extraction, transport and processing of uranium ore, concentrates processing, as well as disposal of sterile ore and waste. The paper will presents specific safety problems related to the identification and evaluation of potential environmental risks, as well as possible radiological consequences associated with the disposal of sterile and the uranium processing waste resulting from processing of the uranium ore. Computer codes will be used, such as IAEA INTERTRAN II and RADTRAN 5. It is also to be noted that this paper considers the main results of the scientific research carried out by the main author as CSI (Chief Scientific Investigator) for Romanian Research Contract on NORM concluded with IAEA Vienna.

Aug 1, 2010

By E. D. Kindle

"The Duthie mine is on the southwest slope of Hudson Bay mountain 7 1/2 miles west of Smithers, British Columbia. A good motor road about 15 miles long connects the mine with the Canadian National railway at Smithers. The principal workings are on the Henderson group of claims between elevations of 3,200 and 4,000 feet above sea-level. Silver, lead, and zinc were produced from this mine between 1924 and 1930.Three adit drifts known as the Compressor, McPherson, and Thompson levels were driven along the Henderson vein-lode in 1922, and the following year the operating company, known as Duthie Mines, Limited, shipped some high-grade silver-lead-zinc ore. Further shipments of high-grade, handsorted ore were made in 1926, and in 1927 a modern flotation-type mill was built, having a capacity of 50 tons of ore a day. Mining operations were suspended in March 1930."

Jan 1, 1954

By A. E. Dyment

In formulating an explosive for any specific set of conditions, various factors must be taken into consideration. Is it to be subjected to water or moisture? .If so, it must be designed to have an inherent ability to resist water. Is it to be used in confined spaces underground, where ventilation is limited? If it is, it must possess qualities enabling it to form, upon explosion, the minimum quantity of noxious gases, such as carbon monoxide or oxides of nitrogen. Is it for use where low temperatures may possibly prevail? If so, it must be capable of resisting such temperatures without freezing. Is it for use where dust or inflammable gases may be present? If it is, then it must be so formulated as to produce, upon detonation, a flame of the lowest possible temperature and the shortest possible duration, in order to lessen the chance of ignition of such gas or dust. This is actually the essential property of a permitted explosive, and it is undoubtedly the most important characteristic of an explosive which is to be used in gassy or closed-light mines. This being the quality that distinguishes permitted explosives from other types, it is interesting to investigate the ways and means by which the low-flame-temperature characteristic is obtained . Generally speaking, such explosives are so designed as to contain comparatively small quantities of nitroglycerin and relatively large quantities of the strength-producing salt, ammonium nitrate. This ingredient does not develop as high a temperature upon explosion as does nitroglycerin, so its presence, in large measure, in place of nitroglycerin results in an explosive which has an inherent low-flame-temperature characteristic, as opposed to one which is .made up largely of nitroglycerin, which would ordinarily be in the high-flame-temperature class. Additions are also made of flame-quenching salts such as sodium chloride, ammonium chloride, and up to a certain limiting percentage of sodium nitrate. These salts, with the exception of the last, do not ordinarily take an active part in the explosive reaction, being present primarily to absorb heat liberated by the reacting ingredients.

Jan 1, 1947

By R. J. Smyth

A Steel Compression Reinforcement Repair Technique (PetroSleevel) system has been developed that has the ability to repair pipeline defects such as stress corrosion cracking (SCC) without requiring welding to the operating pipeline. The Technology has been used to repair active cracking in ERW seam and cracking in the pipe body. All repairs were performed while the pipeline was in operation. This paper will discuss the engineering theory, testing performed to verify the engineering theory, and examples of actual sleeve installations.

Jan 1, 2005

By . A. C. Atenas

Control of arsenic in the Potrerillos' Refinery electrolyte has been obtained by withdrawing a bleed stream of circulating electrolyte and ensuring the ratio of [O]/[As] in the cast anodes is maintained between 0.9 and 1.0. In order to achieve this control the anode oxygen must be adjusted, depending on the arsenic level in the cast anodes. It has been necessary to modify the time of the reduction step in the anode furnace refining process. Control of this ratio has permitted electro refining of anodes with high levels of arsenic, up to 3000 ppm, while minimizing the volume of electrolyte that must be removed for impurity control so as not to affect the copper concentration in the electrolyte. However this control strategy is not useful when the arsenic concentration in the cast anode is too high, because it is limited by the maximum oxygen concentration allowable for a good quality anodic. Costs have been reduced in anode furnace refining because it is no longer necessary to use alkaline flux injection to remove the arsenic in cast anodes.

Jan 1, 2007