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By John T. Bartlett

During the last decade, the increasing price of gold has renewed interest in the various metallurgical techniques for recovering precious metals. Much of the recent technology advance has been aimed at low grade deposits resulting in more complex processes and the necessity of tighter economic control. These factors along with more stringent environmental constraints have made it necessary to optimize each process to minimize energy and raw material consumption and reduce waste discharge. In most cases, detailed process analysis is required to detect inefficiencies and provide alternative solutions for process improvement. Also during this same period, the computer has become widely accepted and computerized mathematical modeling has been applied to an increasingly broader range of problems. Microcomputer based process modeling and simulation systems are routinely used to analyze and improve communition, hydrometallurgical, and pyrometallurgical processes for the recovery of precious metals.

Jan 1, 1987

By Ron Gilbert

Every day, demand increases with over all population; supply must follow. People must have more food, shelter, and mobility. Raw materials must be mined. Roads, trenches and foundations support the quality of life.

Jan 1, 1996

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the ninth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township map. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By N. Morrison, I. Holl, R. Welyhorsky, A. Hempstock

ABSTRACT: The Victor diamond mine is located in the James Bay lowlands, 90 km west of the First Nations village of Attawapiskat. The project was the first of its kind in northern Ontario. The process plant was designed to produce a 95 to 98% by weight diamond concentrate through three stages of comminution, dense medium separation, and proprietary X-ray technology for final recovery. The plant was commissioned over a period of six months, commencing prior to substantial completion of construction. Through effective planning of the commissioning phase, the Victor mine start-up was safely completed nine months ahead of schedule.

Jan 1, 2011

By Luis Alvarez

La productividad de las operaciones mineras está directamente asociada a la optimización de los recursos humanos y de los equipos, por tal motivo se propone la aplicación de un sistema que permite monitorear en tiempo real a los operadores de los equipos mediante el uso de aplicaciones de realidad aumentada, añadiendo información virtual a la información física ya existente.

Sep 1, 2017

By Manuel Gutkrrez, Nasslo Gallardo, Arturo Cancec

The study done in Dofia In&s de Collahuasi aims to improve the fragmentation in one of the most difficult rocks to deal with in an operation, It is the Ignimbrita. In order to avoid ejections and to increase the efficiency of the explosive it has been obtained an improvement in the stemming quality by using the Blasting Optimisation Program in Ignimbrita. Different materials were used in the stemming. In 1997 it was used soil material (Paleorrelleno), then in 1999 started the use of crushed gravel and during this year it is being implemented the utilisation of Stemtite only loaded with drill cutting. The first improvement was obtained with the utilisation of gravel, yielding good fragmentation results in comparison with the stemming with detritus material. The stemtite has made easier the blasting operation and it has signiticantly improved the fragmentation.

Jan 1, 2001

By H. M. Howe

Page 1. Introduction............................514 2. Definitions.............................517 3. Brevity of the Heating........................517 I. THE HARDENING OF THE BORE..............517 4. The Hardening of the Bore.....................517 5. The Thickness of the Hardened Layer.................517 6. Martensitization..........................518 7. The Hardening Repetitive ......................519 8. The Temperature Cycle.......................519 9. The Hardened Layer is the Merged Layer............... 521 10. The Progressiveness of Merging....................521 11. The Progressive Thickening of the Hardened Layer from Round to Round. 523 12. Merging and Hardening are Cumulative................523 13. Three Additional Causes of the Progressive Thickening of the Hardened Layer 525 14. Progressive Roughening of the Bore..................525 15. Avoidance of an Endothermic Transformation.............525 16. Asymptotic Retardation of the Thickening of the Hardened Layer.....527 17. The Troostitic Layer........................ 529 18. The Usual Lack of Martensitic Markings................529 19. The Thickness of the Hardened Layer Should Increase with the Quantity of Heat Taken up by the Walls of the Bore.................530 20. The Decrease of the Thickness of the Hardened Layer from Breech to Muzsle 531 21. Phstic Deformation as a Contributory aCause of Hardening........531 22. In What Way May Plastic Deformation Hasten Hardening?....... 535 23. Possible Need of Coarsening.....................535 24. Carburization as a Cause of Hardening..........:.....536 25. Does Hardening Increase Erosion?..................-538 11. THE CRACKING OF THE BORE ...............539 26. Appearance of the Bore and Cracks in Elevation............539 27. The Cracks in Elevation in the Rear Ring...............539 28. The Cracks in Elevation in the Forward Ring.............540 29. The Copper Network in the Grooves.................540 30. The Cracking of the Lands......................541

Jan 1, 1918

By Natália de Oliveira Roque Maciel

Atualmente uma das maiores preocupações da humanidade está relacionada as questões ambientais, o que tem motivado a pesquisa e o desenvolvimento de materiais provenientes de recursos renováveis e ambientalmente amigáveis. A despeito disso, este trabalho objetiva comparar a resistência de compósitos desenvolvidos com fibras naturais e, portanto, ambientalmente amigável e de compósitos desenvolvidos com fibras de vidro, que por sua vez apresentam impactos ambientais desde a fabricação até o descarte. Foram fabricados 13 corpos de provas para amostras contendo 0% de fibra, 30% de fibra de curauá e 30% de fibra de vidro na matriz epoxídica e ensaiado na máquina de tração. Os resultados obtidos apresentam valores bastante superiores para as amostras contendo fibras de vidro, contudo, ao relacionar a tensão do compósito com a respectiva densidade da fibra, foi possível constatar que os compósitos com fibras naturais chegam a apresentar resultados superiores aos compósitos fabricados com fibras de vidro. É possível concluir, portanto, que do ponto de vista da propriedade mecânica em questão é possível substituir as fibras de vidro por fibras de curauá.

Aug 17, 2017

By Ronald Ticona, Anaani Huaman, Andrea Lucero

Mine-to-mill optimization begins with a clear understanding and ongoing assessment of blasting, crushing, and grinding operations. Modification of blasting practices to optimize feed size can increase a mine’s throughput. However, this is only an initial step. To optimize the entire process and fully utilize downstream equipment, fragmentation must be measured at critical points along the size reduction circuit

Jan 1, 2019

By Stevenson BG

The relevance of ore-dressing mineralogical investigations to developing and improving metallurgical flow-sheets is discussed and examples are given of the application of such studies to various types of ores and mill products (Au, Cu-Sn, Ni and Sn). The mineralogical investigations described illustrate (a) assessment of the feasibility of ore pre-concentration by heavy-media cyclone separation, (b) evaluation of the potential applicability of various metallurgical treatment processes to an ore, and (c) characterization of mill products to assess circuit efficiency and to guide circuit modifications.

Jan 1, 1978

The development of the Moura Coal Preparation Plant is described, commencing with the first'stage of the plant commissioned in 1963. The subsequent expansion stages are traced through to October, 1973. The plant has undergone frequent stages of expansion and modification and this process is continuing. The development programme for 1974 is described as proposed in late 1973. The characteristics of the Moura and Kianga field coal seams with respect to washability are summarised and some comment is made on the blending of these coals prior to washing, to ensure production of export grade coal within specification.

Jan 1, 1974

Traditional loading systems have relied for many years on wheel and track loaders, power shovels, conveyor belts, and more recently, hydraulic front shovels. Each has certain advantages and disadvantages, depending largely on job conditions. Hydraulic backhoes were introduced several years ago as still another truck loading option. At first, buckets were small and backhoe use was limited to small earthmoving projects. Now, as backhoes are equipped with shorter sticks and bigger buckets to move larger quantities of earth. The "mass excavation" concept offers an excellent truck loading option in many situations. System Development and Advantages Mass excavation was first used successfully by contractors in site development and highway construction, loading both on-highway and off-highway trucks. Operators were able to take advantage of the excavator's ability to work in poor underfoot conditions and dig in tough materials. The technique was first applied to mining in the kaolin mines of central Georgia. Kaolin, one of the world's most abundant minerals, is used to make paper, paint, ceramics, rubber, plastics, and many other products. Since kaolin clay is slippery when wet, load-out with wheel loaders is very inefficient. Also, kaolin is found in very spotty deposits due to the weathering process involved in its formation. Consequently, draglines are also impractical for kaolin mining since they don't have the mobility to move between clay deposits. In response to these mining conditions and kaolin characteristics, mines began using excavators in mass excavation as early as 1976. They have developed a system that takes advantage of the excavator's •high penetration and breakout force in tight materials; •fast-cycling hydraulics; •ability to work in poor underfoot conditions; and •mobility in comparison to draglines. This loading method has been successful in Georgia's kaolin mines and now can be applied to other mining operations as well. The excavator's ability to carefully dig spotty ore deposits is an asset at uranium mining operations. Any mine can take ad-

Jan 3, 1982

Constraints on the mineral industry are best treated as issues that have to be understood and managed in partnership rather than in conflict with communities. The Zapopan development at Mt Todd in Australia and the Martha Hill development at Waihi in New Zealand are but two of many recent successful examples at the local level. However, at the national level, the issues are more complex and more difficult to resolve because the most influential stakeholders are now the urban electorates and governments defer to their perceptions when making decisions and policy.

Jan 1, 1995

By A. D. Davis, C. J. Webb, C. S. Johnson, J. L. Porter

The abandoned Belle Eldridge Mine near Deadwood, South Dakota, is on land controlled by the U.S. Bureau of Land Management (BLM) property. The mine produced primarily lead and zinc during the first half of the twentieth century. The BLM has expressed concern about acidic drainage as well as elevated arsenic levels in tailings and waste rock at the site. The mine site was evaluated for remediation in 1998 and 1999. Recent reclamation and remediation work included substantial regrading of waste rock, removal of material where metal loading were of concern, and re-routing of drainage from an adit. Trenching at the site shoed a greater volume than originally calculated during site characterization. Material was removed to a repository that was constructed at a nearby drainage divide. Because of physical hazards, the BLM has decided to remove some historic structures. However, a search of mine records and an inventory of archival materials were complete to preserve the history of the site.

Jan 1, 2002

By Forrest T. Moyer

The overall injury experience, excluding officeworkers, at metal mines and mills during the period 1961-63, reported by operators, was 174 fatal and 11,357 nonfatal disabling work injuries during an aggregate worktime of 451 million man-hours. These injuries occurred at a frequency rate of 25.55 per million man-hours, comprising 0.39 for the fatal and 25.17 for the nonfatal injuries. The combined severity rate of the disabilities was 3,779 days lost or charged per million man- hours, consisting of 2,314 for the fatal and 1,465 for the nonfatal injuries. The average severity of all disabilities during 1961-63, was 148 days per injury. The number of days lost and/or charged, ex- cluding officeworkers, at metal mines and mills during the period 1961-63, was 1,440,000 days charged to fatal injuries and 661,290 days lost from nonfatal injuries. An average of 70,966 men were at work daily. The outstanding cause for fatal injuries was the fall of rock or ore from the back, while most of the nonfatal injuries were caused by handling materials, slips or falls of persons, machinery, falls of rock or ore from back and side, and haulage. Injury experience at primary nonferrous smelters, refineries, and reduction plants during 1961-63, excluding officeworkers, was 23 fatal and 3,214 nonfatal disabling injuries during a total work- time of 277 million man-hours. The injuries occurred at frequency rates of 0.08 per million man-hours for the fatalities and 11.61 for the nonfatal disabilities. The severity rate for all injuries of 1,085 days lost or charged per million man-hours comprised 498 for fatal and 587 for nonfatal injuries. The number of days lost, excluding officeworkers, at primary nonferrous smelters, refineries, and reduction plants during 1961-63 was 138,000 from fatal injuries and 162,385 from nonfatal injuries, An average of 34,938 men were at work daily an active plant days during the three year period. The injury experience for officeworkers at metal mines and mills during the period 1961-63 was 20 nonfatal disabling work injuries, (there were no fatal injuries reported), during an aggregate work-time of 28,694,244 man-hours. These injuries occurred at a frequency rate of 0.70 per million man-hours. There were no fatal injuries reported for officeworkers at non-ferrous smelters, refineries, and reduction plants during 1961-63, but seven nonfatal injuries were reported during an aggregate work-time of 30,814,772 man-hours. The frequency rate for these injuries was 0.23 per million man-hours for this period.

Jan 1, 1967

By Einar Carreño

El artículo evalúa 4 alternativas para el transporte de la mezcla para concreto shotcrete en una operación minera subterránea (Volcan): 1) con planta en el interior de la mina, 2) mezcla enviada por una red tuberías de acero a tubo lleno, 3) mezcla enviada a impacto por un tubo de acero vertical y 4) con un sistema mixto de transporte masivo de relleno cementado. Se evalúan con detalla ventajas y desventajas de cada alternativa y se ofrecen recomendaciones para optimizar el proceso reduciendo tiempo y costos.

Sep 20, 2019

By Jedson Alessandro Damasceno

Atualmente, a maioria dos pátios utilizam recuperadoras com roda de caçambas para remover o minério das pilhas de estocagem. Tipicamente, estas máquinas são operadas manualmente, com todos os movimentos controlados por operadores, o que faz com que o processo seja totalmente dependente de sua experiência, tornando difícil manter o processo em operação ótima. Para alcançar uma melhor performance, foi implementado um sistema automático que controla todos os movimentos de recuperação. Um importante desafio encontrado durante a construção dessa solução foi a de estimar a taxa de recuperação em tempo real, uma vez que esta informação é essencial para o algoritmo que controla o movimento de giro da máquina. Uma medição real dessa taxa está disponível, mas, a balança localizada na lança fica distante da roda de caçambas. Em outras palavras, a medição real está disponível com um grande atraso (aproximadamente 13 segundos). Este delay é inaceitável para o algoritmo de controle que necessita de uma medida em tempo real da taxa de recuperação na roda de caçambas. Diante disso, foi necessário implementar um sensor virtual. Este sensor foi implementado usando um sistema neuro-fuzzy para estimar a taxa de recuperação em tempo real utilizando outras variáveis disponíveis, tais como a pressão na roda de caçambas e medidas de penetração obtidas por radares. As estimativas obtidas ficaram muito próximas dos valores reais, e este sensor pôde então ser utilizado pelo algoritmo de controle.

Aug 17, 2017

This paper outlines the advances made in vacuum filtration as developed by Outomec Process Filters and details the results obtained at a number of Australian installations. The first section of the paper details the technical advances made by the use of ceramic media in vacuum filtration and explains the reasons for the use of the technology. The second part of the paper discusses a number of Australian installations of the ceramic vacuum filter and where possible compares the actual experiences with those predicted from the test work which preceded the installations. The Ceramec Capillary Vacuum Filter is a vacuum disc filter which combines the proven mechanical attributes of a disc filter with exciting new ceramic vacuum technology from Outomec of Finland.

Jan 1, 1991

By B Olsson, C Glassock

Computer simulation modelling (discrete event) has been used at Olympic Dam (OD) to model the handling of ore from the point of extraction at the stope drawpoint through to the ore stockpile on the surface. Computer simulation is a well accepted tool for modelling the behaviour of such large and complex operating systems. It is a particularly useful technique in complex operations where there are multiple interactions between the inputs and outputs of various unit operations. In this instance it can be utilised during the early stages of a project, for example, as part of the business case definition phase or the early engineering phase. A well constructed and tested simulation model provides a sound base upon which informed business decisions can be made. Furthermore, the behaviour of the model with varying inputs can help build a solid understanding of how the asset behaves when varying inputs and constraints are imposed upon it and, as a result, the major points of leverage that designers and operations personnel have to affect the real world behaviour of those assets. Better decisions can be made when the right facts can be examined, various options explored and conclusions tested. Simulation modelling is one of the tools available to make this process work.

Jan 1, 2005

By Kellerwessei H, Oberheuser G

A major breakthrough in extending the life of the wear material of high pressure roll crushers when treating moist, highly abrasive material has removed the last impediment to the widespread acceptance of high pressure comminution in the minerals industry. The system is very energy efficient. It has been demonstrated that in the cement industry energy savings of up to 50 per cent have been achieved compared to conventional hall milling. Besides being energy efficient, the process provides some remarkable and useful effects; ò better liberation of mineral constituents (as proven for diamond liberation). ò preferential comminution where induced micro fissures follow grain boundaries. ò higher reactivity of the product due to micro fissures. All these points will be described here together with a review of current flowsheet design and incentives for the use of this method of Comminution.

Jan 1, 1993