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By D. V. Ziehlke, J. M. Franklin, T. M. Gordon, A. G. Galley

The Snow Lake-Wekusko Lake region of northern Manitoba conta ins numerous lode gold occurrences, including the largest gold deposit in the Churchill Prov ince, the Nor Acme mine. The Aphebian volcanic and sedimentary rocks of this region are comprised of submarine volcanic strata, overlain by turbidites, both of the Amisk Group, and fluvi atile sedimenta ry strata and bimodally composed subaerial volcanic rocks of the overlying Missi Group. Gold occurs as: 1) accessory gold in volcanogenic massive sulphide deposits, 2) lode gold in shear zones related to sy n- to post-FI thrust fa ults, and 3) lode-gold associated with post-F2 fault . An alteration a emblage of biotite, al bite and calc ite is associated with both groups of lode-gold deposits, and has been superimposed on the regionall y-developed metamorphic assemblages. AJthough these deposi ts are spatial ly related to britt le-ductile faul ts of different initial ages, they appear to have all fo rmed after the major period of reg ional fo lding and metamorphism, and thus may be penecontemporaneous. The alteration is different from the sericite-ankerite-quartz assemblage that is typically associated with gold deposits in Superio r Prov ince. Deposits in thi s area of Churchill Prov ince may have formed either at a higher temperature or a deeper structu ra l level than tho e in Superior Prov ince.

Jan 1, 1986

By José Raphael Olegário França

Os vergalhões CA50 bitolas finas 8,00 mm a 16,00 mm, em rolos produzidos via Stelmor são os produtos de maior demanda da CSN aços longos. Estes produtos sofrem tratamento térmico de resfriamento ao ar forçado via esteira transportadora de espiras, após serem laminados e espiralados. Devido a parâmetros e características do próprio processo o produto final apresentava heterogeneidade nas propriedades mecânicas que era causada por um resfriamento diferenciado das espiras, gerando reprovação na inspeção da qualidade. Através do uso de pirômetros para monitorar a temperatura das espiras e uma otimização do resfriamento com defletores do fluxo de ar ao longo da esteira transportadora, tornou-se possível reduzir a heterogeneidade das propriedades mecânicas, assim como a elaboração de ferramentas que ajudam na parametrização do Stelmor.

Aug 16, 2017

By Gabriel Filipe Barrelas Marques Gamito Cardos

O aço em estudo (SAE8620MOD) é um material utilizado na aplicação de estruturas de óleo e gás. Essa liga modificada é utilizada em estruturas off-shore para produção de amarras. Para garantir a qualidade do produto são realizadas uma série de ensaios, dentre eles propriedades mecânicas (RT, LE, Alongamento e redução de área) bem como resultados de dureza e impacto. O ensaio de impacto está relacionado diretamente com a microestrutura obtida durante o processo de solidificação do aço e com o tratamento térmico realizado. Microestruturas com alto grau de bandeamento podem comprometer a variabilidade dos resultados de impacto. A redução ou até mesmo a eliminação do bandeamento é um caso de amplo estudo, principalmente em aços com processo de lingotamento contínuo. Muitas soluções já foram propostas para a redução do bandeamento, o de agitação eletromagnética tem se mostrado bastante efetivo na redução dos níveis de bandeamento e segregação dos produtos lingotados. O ensaio consiste em avaliar a intensidade do campo eletromagnético (FEMS) para o comportamento do nível de bandeamento do material. Foi utilizada uma corrida para teste via lingotamento contínuo, onde a velocidade de lingotamento permaneceu constante e variou-se a corrente dos agitadores em três condições: tarugos com baixa agitação (FEMs com corrente baixa), tarugos com alta agitação (FEMS com corrente alta) e tarugos sem agitação (FEMS desligado). Com baixa agitação no FEMS conseguimos obter um nível de bandeamento menor se comparado com os outros resultados. Como consequência a variação dos valores de impacto apresentaram-se menores que as demais condições, devido a homogeneidade do material. Dessa forma podemos dizer que a redução do nível de bandeamento no material reduziu também a variação dos resultados de impacto, tornando o processo mais estável.

Oct 30, 2017

By M Gabbitus, B Young, T Lukins, M Slater

This paper details the implementation of a new type of grade control system at the Black Star open cut mine in Mount Isa, Queensland. It explores the site requirements for grade control, what as previously in place and what the site required moving forward. It also details some of the features of the system installed and why it was chosen over other grade control systems available. Black Star open cut mine has been in operation since late 2004, and was developed to extract the surface extents of the Ag-Pb-Zn mineralisation previously mined in the Isa Lead Mine. Black Star is currently mining seven distinct orebodies in and around active void hazard zones and hence, its grade control requirements are very detailed and complex. The implementation of a new system to manage the model update and block out processes was, therefore, of critical importance to the site and required a detailed understanding of the requirements of the entire mining team from drilling through to geology, survey and production. Having previously run the grade control process using site specific æblack boxÆ scripts and macros, Black Star needed to implement a more open, auditable and flexible system, which allowed the geologists to control the process and make strategic changes as the situation demanded. MineSightÆs Axis Grade Control, with its flexible, generic framework for managing the process, met these demands. Being an out of the box solution that requires minimal setup and training was also a key factor in the decision to use it.CITATION:Lukins, T, Slater, M, Gabbitus, M and Young, B, 2012. The introduction of axis at Black Star Open Cut, in Proceedings Eighth Open Pit OperatorsÆ Conference , pp 71-74 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 18, 2012

By P. Gray

Process and engineering development of the Warner Zinc Process over the past two decades has proceeded alongside the world-wide collection and analysis of operating and cost data of current processing practices from sulphide ores to refined metals. Study of these data shows that recoveries are dependent on mineralogical characteristics of the sulphide matrix and point to the inadequacy of differential flotation as a tool for preparing feed for smelters. The paid-for return at the mine on the combined metal values in zinc rich sulphide ores rarely exceeds 80% and increasingly runs as low as 50-60%. Surveying the possible alternative ways of improving these performances leads to the conclusion that the Warner Process is the only technology in sight that could meet a target of 90% paid-for recovery and that its development has now reached a point where it can be a fully practicable process for all mixed sulphide ores.

Jan 1, 2000

Hazardous waste has often very complicated chemical compositions in a variety of physical forms and is normally processed in rotary kiln incinerators. Due to large variations in waste types and difficulties in feed characterization, the complex transport processes within the incinerator are not well understood, and the incineration process meets challenges in a smooth operation, and expects various uncertainties in the process chemistry and emission control. For better understanding of the incineration process, simulation was carried out by using Computational Fluid-dynamics (CFD) to characterize temperature and species distribution in the incinerator. In order to catch certain aspects of thermal and chemical behavior, a novel approach is proposed to represent approximately the waste streams and the subsequent combustion process. Hazardous waste in various forms from an industrial-rotary-kiln waste incinerator is firstly converted to a hydrocarbon-based virtual fuel mixture with approximately the same HIC molar ratio and calorific value. The simulation of the combustion process of the simplified hazardous waste was proceeded with a combustion model. The distribution of temperature and chemical species especially the remaining CO in the system is preliminarily investigated. Distribution of CO concentration, as a good indicator of emission level for the incineration process, could be used to evaluate the emission control. The predicted temperature distribution has been compared with available measurement data from an operating rotary kiln waste incinerator at A VR-Chieme, in the Netherlands. Reasonable agreement has been reached between the measured and predicted temperature data. [n the next step, measurement of species distribution in the system is planned to further validate the combustion model.

Jan 1, 2003

By D. Rucker

Flow models are used to predict the extraction efficiency of metals in rock piles. These models typically use hydraulic parameters obtained through column studies, which assume that the material in the column wholly represents the entire pile and the parameters can be upscaled several orders of magnitude for model evaluation. This assumption fails for parameters that are spatially variable or scale dependent. To overcome these issues, measurements made directly on the heap at the appropriate model scale can be made with the electrical resistivity method. The method aims to map the variations in the electrical resistivity, which can be associated with moisture content, degree of fines, metal content, and leachate concentration. We present an example of calibrating the resistivity with borehole measurements of moisture using geostatistics to show how the resistivity method can be used to obtain a spatial moisture distribution. It was shown that cokriging the resistivity and moisture together gives a more reliable distribution.

Jan 1, 2010

By Antony Amberg, Gonzalo Saldías, Romke Kuyvenhoven, Catherine Souza, Heriban Soto, Francisco Soto

"Vizcachitas is an advanced stage copper–molybdenum porphyry deposit, fully owned by Los Andes Copper and located in Central Chile. The property contains an indicated resource of 1,038 million tonnes grading 0.37% Cu and 0.012% Mo, and an inferred resource of 318 million tonnes grading 0.345% Cu and 0.013% Mo (Coffey & Alquimia, 2014). The deposit occurs in the same geological belt as several other giant copper-molybdenum porphyry deposits including Río Blanco-Los Bronces, Los Pelambres-Pachon and El Teniente. In 2018, the original Preliminary Economic Assessment (PEA) study from 2014 was updated; this paper presents the geometallurgical testwork that was performed to support that update. The testwork focused on the metallurgical characterization of 40 DDH samples and the development of a more profound orebody knowledge by relating geological features with metallurgical performance. The scope of work included complete chemical and mineralogical QemSCAN characterization; SAG, ball mill and abrasion testing; complete rougher and cleaner kinetics including locked-cycle-test; environmental ABA and settling tests on rougher tailings. The results show that the ore can be classified as medium-hard, with a hardness that is slightly below the average for large Cu/Mo deposits in the region. A good correlation was found between lithology and breakage characteristics, implying that the specific energy consumption (kWh/t) is well correlated to rock type. The results of the flotation tests were very encouraging and did not show significant variability. An overall Cu recovery of 91% can be expected for the flotation circuit. The use of a relatively coarse primary grind size gave good final recovery and grade for both Cu and Mo, and deserves further attention in future work, as this impacts positively both energy consumption and water recovery.INTRODUCTION Los Andes Copper Ltd. is a Canadian exploration and development company focused on the acquisition, exploration and development of advanced stage copper deposits in Latin America. The company owns 100% of the Vizcachitas project in Chile, the largest copper deposit in the Americas not controlled by the majors. Vizcachitas is a copper-molybdenum porphyry deposit, located 120 km north of Santiago, in an area of very good infrastructure."

Jan 1, 2018

By T. M. Dreher

The difficulties associated with the operation of a classical rhodium refining process have prompted many attempts to develop a viable solvent extraction flowsheet for rhodium. Recent investigations at McGill University have involved the activation of rhodium prior to its solvent extraction. The role of activation is to convert the aquochloro complexes of rhodium to a form extractable by conventional solvent extraction reagents. In the novel separation scheme identified, chloro complexes of rhodium are converted to bromo complexes, which undergo aquation to a lesser extent, making them more easily extracted. Rhodium is then extracted using Kelex 100, and stripping is achieved by use of a concentrated chloride based solution. Separation of rhodium from iridium is achieved by either prior reduction of Ir(IV) to Ir(III), as the latter is not extracted, or via co-extraction and differential stripping. A conceptual flowsheet for the refining of rhodium using this method is proposed.

Jan 1, 1998

By J. E. Chilton

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro-chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1-to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light-emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 2010

By John Rajala

The Otjikoto Gold Mill was commissioned during November–December 2014 as Namibia’s first new gold producer in 30 years. Its operations consist of surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and gold recovery. The initial mill design capacity was 2.5 Mt/a. Its capacity was expanded after nine months of operation to 3.1 Mt/a, and process performance has significantly surpassed design expectations. After startup, the Otjikoto Mill’s throughput and gold recovery ramped up quickly, with both parameters exceeding design after only two months of operation. The robust process performance continued into 2019, with key performance indicators (KPIs) eclipsing design values in almost every aspect of mill operation. The Otjikoto Mill’s gold recovery is exceptionally high, exceeding 98 percent every year following startup, especially considering the low-grade nature of the deposit.

By H. E. Montgomery

Engineering trends for some years have been toward higher temperatures, both in process work and in steam generation. Progress in design has been dependent upon the development and evaluation of suitable alloys. Elementary knowledge of the limitations of copper-base alloys indicate their unsuitability for the higher ranges of operating temperatures; say, for steam to 950°F. Emphasis upon the more severe conditions perhaps is a reason why more complete evaluations have not been made for copper-base alloys over their range of suitability. However, the few studies made show clearly the need for more accurate evaluations. Some copper-base alloys long looked upon favorably because of superior room-temperature properties are not as desirable as some others perhaps not so "strong" and "hard," as measured by usual acceptance tests. Load-carrying capacity and structural stability arc two important factors. Structural stability as influenced by temperature, by presence of corrosive media, or by the effects of stress itself, frequently is a limiting factor. An early reference to creep properties of the cast copper-base alloys is that of Brown1 (Admiralty gun metal, Cu 87.5, Sn 10.1, Zn 2.3 and Pb 0.08). His tests were similar to present-day stress-rupture tests without measurement of creep elongrttion. Loading was in steps with usually 24 hr. between steps, and continued until failure. He advocated a "useful strength value" of 61/2 tons (I4,560 Ib.) per sq. in. at 572°F. (300°C.). A specimen broken in 1/2 hr. at 572°F. had a strength of 21 tons (26,880 Ib.) per sq. in. The strength values as determined by 1/2-hr. tests and those by the longer stress-rupturc start to differentiate at 392°F. (200°C). This is the temperature at which time at load began to play an important part. Bolton, Price and Hebemann2 give creep curves on 88-10-2 (A.S.T.M. B-60, CU 88, Sn 10, Zn 2) and steam or valve bronze (A.S.T.M. B-6I, Cu 87.50, Sn 6.00, Zn 3.75, Pb 1.70) at 500°F. Direct comparison of the two alloys under 7500 lb. per sq. in. stress showed the steam bronze (A.S.T.M. B-61) superior in creep strength to the 88-10-2 (A.S.T.M. B-60). The steam bronze shows no creep after 700 hr. (1540-hr. test). The 88-10-2 shows a rate of about 7.0 per cent in 100,000 hr. over the last 700 hr. of the test. Creep curves on the steam bronze are also given at the same temperature (500°F.) with loads of 6500 lb. per sq. in. and 8000 lb. per sq. in. These indicate "creep strengths" (creep rate within I per cent in 100,000 hr.) in excess of 8000 lb. per sq, in. for this alloy. It was found that higher percentages of tin are detrimental to creep resistance. This is caused by the presence of or formation during test of considerable alpha-delta eutectoid in the higher tin alloys. Bolton also states that the high

Jan 1, 1945

By AIME AIME

OPPORTUNITY may not be knocking but it, at least, is waiting for you, your family and your friends in that amazing republic south of the Rio Grande. For the first time we are able to publish the official itinerary for the forth-coming Mexico City meeting of 1936. As shown on Page 351, the deluxe special train leaves St. Louis on Thursday. Nov. 5 at 5:30 p.m., returning to St. Louis on Nov. 18 at 8:15 a. m. The schedule provides seven days and six nights in Mexico City with numerous excursions to nearby towns and resorts. The oldest surviving city in' North America is Mexico City, dating back at least to the twelfth century. It was the Aztec capital when Cortez arrived in 1519. The famous cathedral still standing was built on a foundation of sculptured Indian images and the remains of a great Aztec temple. Today it is a city of romance.

Jan 1, 1936

The Bureau of Mines, U.S. Department of the Interior, devised a flotation technique for upgrading chromite in chromium ores and gravity concentrates. The technique consisted of cationic flotation of chromite from a slime-free pulp acidified to pH 2.5 or lower using H2S04 modifier. Flotation results showed that ore containing serpentine as the primary gangue mineral was more amenable to concentration by this technique than ore containing the readily floatable olivine as the primary gangue mineral. Rougher flotation of a chromite ore containing abundant serpertine increased the grade form 19 to 41 percent Cra03 at a chromite recovery of 89.6 percent. Rougher flotation of ore containing abundant olivine upgraded the chromite from 23.4 to 29.6 percent Cr203 at a recovery of 89.4 percent. The technique was also applied to chromite gravity concentrates to further upgrade chromite and to reject silicates. Flotation of a gravity concentrate containing 40.9 percent Cr203 and 4.4 percent SiO2 recovered 90 percent of the chromite in cleaner products containing 44.9 percent Cr203 and 0.63 percent Si02. The combined recovery by gravity and flotation was 87 percent. An economic evaluation of this technique will be undertaken to deter-mine its feasibility for commercial use.

Jan 1, 1980

By L. C. Morganroth

Magnesites are of two general classes - massive and crystalline.

Jan 1, 1915

By A. J. Kraemer

This report on the physical and chemical properties of crude oils of California is one of a series on the producing districts of the United States. It includes a short discussion of results, tabulated data, and individual analyses of California crudes. Analyses of crude oils from the fields of Fresno, Kern, Los Angeles, Orange, and Ventura Counties have been published in Serials 25952 and 26083. The analyses reported in this paper corer samples that were obtained subsequent to the publication of Serials 2535 and 2608. The samples were obtained by members of the San Francisco office of the Bureau of Mines. The collecting of samples was facilitated by the courtesy of representatives of oil companies in California.

Jan 1, 1927

By P. Fellner, A. Sýkorová, J. Thonstad, J. Jurišová, V. Khandl

Adsorption of S02 on alumina used in the aluminium industry, so-called smelter grade alumina, was studied in the temperature range 15 C-120 C. The specific surface area of the smelter grade alumina was 88 m2/g. It was found that at temperatures lower than 40 C, sulphur dioxide is bonded to alumina reversibly by physical forces, and the adsorption can be described satisfactorily by the Langmuir adsorption isotherm. The heat of adsorption was estimated to be -33 kJ.mor1. At temperatures in the range 80 C- 120 C, which prevail in dry scrubbers in the aluminium industry, the heat of adsorption was determined to be -56 kJ.mor1. When S02 was adsorbed at temperatures higher than 80 C, about 30 % of the S02 could not be desorbed when heating the samples up to 250 C. In the presence of S02 and oxygen, the formation of sulphate was determined at temperatures above 90 C.

Jan 1, 2006

By AIME AIME

THE Board of Trustees, made up of three from each of the four societies, conducts the business com- mitted to United Engineering Society by its Founder Societies under its Charter, the Founder's Agreement and the Library Agreement. A draft of a budget of revenue and expenditures for the ensuing calendar year is presented each September to the secretaries of the Founder Societies for the information and comment of their governing bodies. After revision, the budget is adopted, by the incoming Board of Trustees at its meeting in January.

Jan 1, 1929

By Jocemir da Silva Santos, Alberto Vicente Belezia, Matheus Neves Lana

A regulação ambiental de processos industriais que geram efluentes contendo fluoretos é mundialmente restrita devido à alta toxicidade do íon. Na Ternium, a água de resfriamento recirculada no spray do Lingotamento Contínuo (WTP#2) dissolve parte do pó fluxante, resultando em concentrações de 20 a 30 mg/L de fluoreto. Para desenvolvimento do processo de tratamento de fluoreto que atendesse a legislação, mantendo no efluente tratado concentração de Fluoreto menor que 10mg/L e Alumínio menor que 3,0mg/L, foi realizada uma pesquisa utilizando um equipamento de Jar Teste convencional totalizando 165 ensaios. Os ensaios foram planejados segundo revisões bibliográficas descrevendo o método da precipitação química de fluoreto de cálcio, auxiliado por Cátions de Alumínio. Na conclusão da pesquisa, foi desenvolvida uma Rota Tecnológica para tratamento do efluente gerado na purga do sistema WTP#2 atendendo a legislação, atingindo uma remoção de 70% a 80% de Fluoreto. Ao final foi realizada uma etapa de otimização das dosagens, cujo resultado foi a redução do número de etapas de tratamento e uma redução na quantidade de produtos químicos utilizados, consequentemente reduzindo o custo de tratamento. A redução do custo de tratamento foi da ordem de 3 milhões de reais anuais, mantendo o efluente tratado com as concentrações dos contaminantes abaixo dos limites da regulação ambiental.

Aug 1, 2019

By M. Sadegh Safarzadeh, Stanley M. Howard

The two-dimensional predominance area (Kellogg) diagram (PAD) surfaces bounding the three-dimensional Cu-As-S-O system were constructed at 900 K. The computations employed gases As4O6(g), O2(g), and SO2(g) as the independent coordinate species to generate diagrams of As4O6(g) − O2(g),O2(g) − SO2(g), and As4O6(g) − SO2(g), while the third gas (As4O6, O2, or SO2) was fixed. The results indicate that there is no shared boundary between enargite (Cu3AsS4) and copper sulfate (CuSO4); however, at PO2 < 10−6 atm, PAs4O6 < 10−10 atm, and PSO2 > 10−4 atm, CuSO4 is the stable phase at 900 K. The chemical driving force for oxidation of intermediate phases between enargite and copper sulfate is substantial except for basic sulfate (CuO · CuSO4).