Search Documents

By Charles Knilans, Tassos Grammatikopoulos, Nicole Hoffmann

"Twin Metals Minnesota LLC, (TMM) has recently completed a prefeasibility study evaluating the development and operation of an underground copper (Cu), nickel (Ni), platinum (Pt), palladium (Pd), and gold (Au) mining project on the Maturi deposit in northeastern Minnesota.The Maturi deposit is a magmatic Cu-Ni-sulphide deposit occurring along the basal contact of the South Kawishiwi intrusion, comprised of heterogeneous troctolites to gabbros forming a tabular body designated the BMZ (basal mineralized zone). These rocks provide the major gangue mineralogy (plagioclase, olivine, and clinopyroxene) with local, minor rock-forming orthopyroxene, biotite, magnetite, and ilmenite. Altered silicates exist within local fracture and/or alteration zones, which are commonly associated with minor faults in the regional area. The Maturi deposit is comprised of four main mineralized zones within the BMZ, referred to as Stage 1, Stage 2 (S2), Stage 3 (S3), and Upper Heterogeneous. Chalcopyrite, cubanite, pentlandite, and pyrrhotite are mainly hosted within the S2 and S3 units, with talnakhite frequently occurring within the S3 unit.A cross-discipline approach combining geology, geochemistry, metallurgy, QEMSCAN™ mineralogy, and mine planning has been implemented to develop a preliminary geometallurgical model and life of mine metallurgical performance forecast. This paper provides an overview of the methods that were used to develop the model and forecast, and discusses the advantages of such a model in project development and evaluation.INTRODUCTIONThe TMM Project proposes mining a copper-nickel-palladium-platinum-gold-silver (Cu-Ni-PGM) magmatic sulphide deposit situated in the Duluth Complex of northeastern Minnesota, USA. The prefeasibility study proposes a 45,000 million tonnes per day mine and concentrator facility to produce two saleable concentrates. The mine will access two separate deposits, Maturi and Maturi Southwest. Saleable concentrates are the final products of the sequential flotation plant where a high grade Cu concentrate is produced followed by a Ni concentrate."

Jan 1, 2015

The Department of Mineral Resources has a statutory responsibility for mine site environmental management and control in New South Wales. The Department is focusing on an environmental management systems (EMS) approach, as a management tool to achieve æbest practiceÆ outcomes both within our own organisation and on mine sites. One of the DepartmentÆs tools is environmental risk assessment and management which incorporates the Mining, Rehabilitation and Environmental Management Process (MREMP). The MREMP was introduced many years ago in order to integrate the activities of key stakeholders who may have a material interest in the mine. The MREMP provides an ideal mechanism by which ædue diligenceÆ requirements and environmental management programs can be integrated into mining operations and lead to a sustainable post-mining land use.

Jan 1, 2002

By Noel N. Moebs

This report summarizes a U.S. Bureau of Mines study on the application of geotechnology to identify and minimize ground control hazards in talc mining operations in northwest Georgia. The major ground control hazard is pillar sloughing attributed to the steeply dipping orientation of a pronounced foliation in the talc ore body. The sloughing problem, which gradually reduces the effective support area of a pillar through attrition, can be minimized by appropriate artificial support, as determined by a rock classification system, and by a more uniform pillar design. A boundary element model confirmed the advantages of using a uniform pillar design to avoid excessive loads on portions of irregular pillars. Instrumentation to measure roof convergence and pillar loading was installed at selected locations in an active talc mine but failed to detect any significant changes, suggesting that the gneiss hanging wall constitutes a strong roof that probably can support large spans between pillars and permit high extraction ratios. This interpretation also is supported by a rock classification of the hanging wall gneiss.

Jan 1, 2010

By K. C. Sole, G. Robinson, M. S. Moats, W. G. Davenport, S. Sandoval

Global practice in hydrometallurgical production of copper cathode by electrowinning is reviewed, based on individual plant operating data for 2018. Data from 29 plants were collected, representing 38% of world cathode copper production. Similar surveys were carried out in 1997, 1999, 2003, 2007, and 2013. This survey includes analysis of historical and current data. Evolving trends in operating conditions and performance, as well as equipment design and process technology choices, are analysed and differences in operating practices with location are assessed. Examples of recent technology and operational choices to increase productivity, improve copper quality, and decrease electrical energy consumption are discussed. Significant project expansions, particularly in Africa, and the consolidation of numerous small Chinese operations are also presented. INTRODUCTION Global trends and operating practices in copper electrowinning (EW) in 2018 are reviewed and evaluated. Similar world and African surveys were carried out in 1997, 1999, 2001, 2002, 2003, 2007, and 2013 (Robinson, Davenport, & Jenkins, 1997; Jenkins, Davenport, Kennedy, & Robinson, 1999; Davenport, Jenkins, Robinson, & Karcas, 2001; Robinson, Garbutt, & Davenport, 2002; Robinson, Davenport, Jenkins, King, & Rasmussen, 2003; Robinson, Davenport, Moats, Karcas, & Demetrio, 2007; Robinson, Sole, Sandoval, Moats, Siegmund, & Davenport, 2013). Contributing operations included sites from the USA and Mexico (9), Chile and Peru (6), Laos (1), Kazakhstan (1), and Africa (9). Despite fewer contributions compared with past experience, this survey nevertheless represents 2018 copper EW cathode production of 1.76 Mt, or about 38% of world production of 4.64 Mt (International Copper Study Group, 2017). This drop in permission to contribute is attributed to the more competitive nature of the industry and unprecedented production pressures; furthermore, several operations in Australia have shut down, while large operations that are currently commissioning or ramping up to full production in Africa and Asia declined to participate. Of the Chinese operations, which represent an increasingly important proportion of global electrowon cathode copper, particularly in Africa, only Tenke Fungurume (Democratic Republic of Congo; DRC) participated in this survey.

Jan 1, 2019

By C. A. Brown

"Steady-state simulation has been used for over 20 years to optimise the operation of crushing and grinding circuits. Throughout that period continuing comminution research has been the basis for improving the models.Site surveys, ore characterisation, model development and investigation of different operating scenarios by simulation has proved to be a cost-effective method for improving plant performance. In this sense, this paper presents findings from experience with these valuable optimisation techniques with reference to specific case studies."

Sep 12, 2005

The Earth?s population is approaching 6.6 billion people. More than half live in urban areas. And, as those figures continue to grow, the need to make wise use of the world?s natural resources as well as its living space will also grow. Thus, the concept of sustainable development ? meeting the needs of the current generation while preserving resources for future generations. The use of underground space is only one part of the sustainable development concept. But it is an important one. Tunnels and underground space are environmentally friendly and contribute significantly to sustainable development. But it takes years to plan and build tunnels and other underground infrastructure. And the demand for infrastructure in the world?s mega cities has grown significantly. In December, about 100 people representing several developed and developing nations spent a day at the United Nations (UN) in New York City discussing the future of underground space development throughout the world. The meeting was put on by the UN?s Department of Economic and Social Affairs and the International Tunnelling and Underground Space Association (ITA). The conference was titled ?The Use of Underground Space as an Unexpected Solution for Promoting Sustainable Development.? Its aim was to promote practical solutions to the use of underground space and tunnels as feasible alternatives to promote sustainable development throughout the world. A panel of speakers from government, academia, the UN and the ITA stressed that development is not sustainable without infrastructure. And, as the world?s population grows, there is now an urgent requirement to efficiently plan for the use of underground space to preserve it for the future benefit of mankind. The benefits of the use of underground space are many, they said. Among them: ? Tunnels channel clean water in and waste water out. This promotes health and sustainability worldwide, particularly in developing countries. ? The use of tunnels and underground space helps conserve energy and increases its efficient use ? the use of tunnels cuts commuting time and so saves energy. ? Tunnels, microtunnels and other underground structures promote the more efficient use of space in large cities ? the bulk storage of water, fuel and other goods. ? Underground structures are subject to less stress than surface structures, making them safe havens for natural and man-made hazards, including earthquakes. And, because underground structures are more durable, lifecycle costs are less than surface structures. ? Underground structures promote the multiple use of available land. Land owner-ship at several layers increases land use and provides more usable space. Han Admiraal is director of the Center for Underground Construction in the Netherlands. He said that urban planners need a new vision concerning the use of underground space. Going underground protects historical and archaeological surface facilities, he said. Underground space use can also protect populations located in adverse climates. And sensitive environmental areas on the surface can also be protected from development. In addition to the transportation of people, freight and water, underground development can also store water, as well as provide storage for waste, hazardous materials, carbon dioxide and geothermal energy. The upshot of this new awareness and vision for under-ground space is that its use should be considered before surface development, Admiraal said. And planners and developers are placing more emphasis on underground space development as part of their overall development plans for urban areas. That was not always the case, he said. In the past, underground space was not considered until after the surface space had run out, he said.

Jan 1, 2008

By P Kirsch, P Jagals, D Viswanathan, J Shandro, R LaBouchardiere

The planning, design and operation of mines must include the development of positive environmental, community and land-use benefits if it is to achieve good corporate social responsibility and minimise detrimental impacts throughout the life of the mine. Life-of-mine (LOM) planning should, therefore, consider conducting mining activities in the best socially, environmentally and economically acceptable manner, from the commencement of exploration to post-closure of the mine. Current knowledge of LOM activities in relation to public health (life-of-community, or LOC) impacts neither fully captures the full suite of human health and well-being impacts, nor comprehensively informs society on these issues. This knowledge gap is becoming more apparent as public antipathy is increasing towards mining activities within Australia, Canada and globally. The purpose of this paper is to present preliminary and informative results of a literature review to gain insight into the extent of available public health and well-being knowledge associated with mining development. LOM development must also benefit the LOC, in that it must aim to minimise detrimental impacts, and maximise beneficial (including health) impacts on all associated communities. Health planning and programing for mitigation of potential adverse health impacts of mining should extend beyond the scope of work-related injury and illness (resulting from chronic exposure to harmful substances, infectious and lifestyle illnesses), to the health and well-being of workersÆ families and extended associated communities. By mapping the available but rather scarce literature on LOC areas to recognised LOM stages, this review found shortcomings and imbalances regarding research reporting on mining and its health-related impacts in the worker-to-community continuum.CITATION:Kirsch, P, Viswanathan, D, LaBouchardiere, R, Shandro, J and Jagals, P, 2012. Health impacts extend from the life of a mine to the life of a community - Knowledge gaps, in Proceedings Life-of-Mine 2012 , pp 161-168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By Leslie F. Sawatsky

Raw water import requirements for oils sands mines depends mainly on factors such as ore processing rate, ore material characteristics, tailings processing technology, tailings storage systems, process water storage operations, the phase of tailings production, and non-recoverable seepage losses from tailings ponds. These factors can be readily quantified to calculate raw water import needs. Nevertheless, mine water balance continues to be misunderstood by some regulators, stakeholders and possibly even mine operators. Confusion over consumptive uses has led to a focus on recycling which is not necessarily applicable to a closed circuit water management system. Some water conservationists focus attention on raw water intake rules instead of the technical decisions that control consumptive uses. Typical oil sands mine water balances for various types of tailings operations, are analyzed to illustrate the effect of controllable and uncontrollable parameters as well as major options that need to be explored for reducing water demand. Uncontrollable parameters including tailings fines content, oil content of ore, connate water, mine depressurization water inflows and surface water hydrology. Controllable parameters include storage operations, advance water supply ahead of mining operations, type of tailings operation, net tailings pond seepage losses, and tailings impoundment operations. Potential reductions of raw water supply rates may be obtained by providing greater on-site storage to attenuate fluctuation in water demand, advance water accumulation prior to mine start up, early commencement of CT operations, thickened tailings disposal and paste technology. Water conservation measures should be focused on reducing on-site process water storage and water content of tailings material.

May 1, 2004

Coal research and related activities in 1964 by the Bureau of Mines resulted in many advances in the production, preparation, and utilization of this valuable natural resource. Mining research during the year was marked by work on hydraulic mining, coalbed degasification, mine drainage control, mine sealing, strip-mine rehabilitation, and quenching of mine-refuse fires. Bureau research continued to produce information leading to increased safety in underground mining. Such research included roof and rib control via bolting and bonding, pressure monitoring of coal and mine rock during mining operations, and development of safety devices for detecting conditions leading to roof falls. Other safety work was continued on methane detectors, coal-dust suppression, and mine ventilation equipment and techniques. Mine explosion and explosives research, mine equipment and materials, safety rule modernization, and safety education and training of mine workmen were continued. Coal storage and preparation work in 1964 ranged from freezeproofing of lignite for rail shipment, through washability studies of coals and washing equipment, to research on new ways to remove ash and sulfur from coal. Electric power production, which accounts for a major portion of the market for coal, received further study. Unique power generation systems, including coal-burning gas turbine and megnetohydrodynamic generators, were intensively investigated. Conventional power systems were improved through continuation of work on furnace performance, powerplant stack gas purification, and engineering and boiler water service.

Jan 1, 1965

By Oliver Bowles

Whiting or Paris white is a fine-grained preparation of calcium carbonate having a wide variety of uses. Until recent years it was prepared almost exclusively from certain north European chalks. With the curtailment of imports of European chalk during the World War of 1914-18, however, finely ground limestone, of domestic origin was used more extensively to satisfy the American demand.

Jan 1, 1942

By D. R. Wilburn

This summary of international mineral exploration activities for 2012 draws upon information from industry sources, published literature and U.S. Geological Survey (USGS) specialists. The summary provides data on exploration budgets by region and mineral commodity, identifies significant mineral discoveries and areas of mineral exploration, discusses government programs affecting the mineral exploration industry and presents analyses of exploration activities performed by the mineral industry. Three sources of information are reported and analyzed in this annual review of international exploration for 2012: 1) budgetary statistics expressed in U.S. nominal dollars provided by SNL Metals Economics Group (MEG) of Halifax, Nova Scotia; 2) regional and site-specific exploration activities that took place in 2012 as compiled by the USGS and 3) regional events including economic, social and political conditions that affected exploration activities, which were derived from published sources and unpublished discussions with USGS and industry specialists.

May 1, 2013

By R. O. Kneisley

This U.S. Bureau of Mines report summarizes a study of large-scale strata response to longwall mining at a western U.S. coal mine. This study utilized surface and subsurface measurements, geologic mapping, in situ stress measurements, and pressure cell readings to characterize strata behavior. Preliminary analysis of surface subsidence and time-domain reflectometry (TDR) was used to determine a suggested main roof caving sequence. Coal ejected from the face apparently resulted from brittle failures that occurred because of lack of significant yield zone development. The combination of a strong coal with pronounced directional behavior, low overburden pressures, a good caving roof, and a high-production environment that minimized time-dependent loading apparently reduced yielding of the longwall face. The panel 1 headgate-entry design appears adequate; however, the abutment pillar and adjacent panel tailgate rib are highly stressed and may contribute to problems during second panel mining. The small chain pillar yielded after passage of the face, but the pillar width may be near maximum since evidence of a stressed core exists.

Jan 1, 2010

By R. C. Troxell

Alternative methods of analyzing data acquired by the Morenci copper concentrator process control instrument-computer system are presented. Experimental measures of ore characteristics, for proposed feed forward control, are introduced. These include on-line indexes of ore hardness, ore density, ore dusting, and ore color. Comparison of metallurgical results before and after computerized process control implementation, allowing for differing ore grades, oxidation, hardness, and fineness of grind, also is described.

Jan 1, 1979

By Peter Haller

Introduction The impact of the Comprehensive Environmental Response, Compensation, and Liability Act, or Superfund, as well as the Resource Conservation and Recovery Act (RCRA) and their state counterparts underscore the intention of the nation's lawmakers to reduce the risk from hazardous substance to American society. The promises and requirements embodied in these laws, together with their prospects for liability, will continue to have a very substantial impact on decision making in the mining industry. These laws present the prospects for staggering liabilities, often of an unquantifiable nature in terms of time and amount. It is therefore necessary to keep them in clear focus. This is particularly true in light of President Reagan's signing into law the Superfund amendments on Oct. 17, 1986, and in light of the Environmental Protection Agency's (EPA) major policy pronouncement of July 3, 1986, regarding solid wastes from extraction of ores and minerals. This article examines the general trends as well as the specific provisions of these laws in an effort to assess the prospects of liability for the mining industry of releases of hazardous substances into the environment. Hazardous substances vs. hazardous wastes The distinction between the terms "hazardous substances" and "hazardous wastes" is important to appreciate for the purposes of assessing the potential for liability for a mining operation. Hazardous substance is a term that appears in and is defined in the Superfund Act. In Superfund, it is defined by reference to other substances that have been declared to be hazardous under other federal environmental statutes, such as RCRA, the Clean Air Act, and the Clean Water Act. Hazardous waste is a term that is less all-encompassing than hazardous substance, as that term is defined by RCRA. Hazardous substances do not need to be wastes to be considered hazardous for the purpose of Superfund liability. A "release" of a hazardous substance into the environment can bring about potential liability under Superfund. Many mining wastes, even though they are not considered hazardous wastes by EPA under RCRA, have been determined by that agency to be capable of bringing about liability under Superfund if they contain chemical substances, such as the heavy metals copper, lead, mercury, zinc, silver, and others. Therefore, it is not sufficient for the mining industry to be able to answer whether one has hazardous waste at a mining site. That question only goes partway in addressing the potential for liability. The next question is, do one's solid or liquid mining wastes contain hazardous substances that could bring about liability under Superfund? Superfund 1980 law: A review Some provisions of Superfund as it existed before its recent amendments must be considered. The law provides that the owners and operators of mining sites, together with those who transport hazardous substances to such sites, can be held jointly and severally liable for the cost of cleaning up the site. The concept of joint and several liability means that one party, as among many, can be held totally responsible for the costs of cleanup. This is particularly true where the harm done by many parties to the envi-

Jan 2, 1987

By E. I. Gedgagov, A. V. Tarasov, V. M. Paretsky, A. D. Besser

"Hydrometallurgical technology and equipment have been developed in the Gintsvetmet Institute (Moscow, Russia) for processing of rhenium-containing alloys waste to produce commercial- grade metal products with recovery of all valuable components. The technology is based on waste treatment with hydrofluoric acid with subsequent decomposition with nitric acid at pH = 1 to 1.5 to ensure maximum degree of rhenium conversion to the liquid phase of pulp. Some experimental lots of ammonium rhenate and ammonium molybdate were produced at a pilot plant. The following main techno-economic performance values have been achieved when processing grinding residues (balance-based tests were conducted with a lot of SP-2 alloy waste) to produce ammonium rhenate of high purity, as well as tantalum-niobium, nickel-cobalt and tungsten-molybdenum concentrates: rhenium recovery of 92.3% into a commercial product from grinding waste; production cost of 170-210 US Dollars per 1 kg of rhenium in commercial-grade ammonium perrhenate taking into account its recovery; tantalum and niobium recovery of 75- 77% into bulk concentrate; nickel and cobalt recovery of 88-89% into a mixed concentrate; tungsten and molybdenum recovery of 88% to 91% into concentrate. Introduction During the recent years the use of rhenium has been increasing at a fast pace worldwide [1]. The growing prices for this refractory metal are an essential factor encouraging collection and processing of rhenium-containing wastes. Double-component waste, such as molybdenum- rhenium or tungsten-rhenium alloys can be readily decomposed and the process of rhenium recovery does not cause, therefore, any difficulties. The main separation of metals takes place at the stage of waste digestion with acid, because molybdenum and especially tungsten remain in precipitate in the form of hydrated oxides and rhenium reports in the liquid phase, from which it can be easily extracted by solid ion-exchange or solvent extraction techniques. However, most of rhenium is contained in super-alloy waste [2]. Such waste has different contents of valuable components, such as tantalum, niobium, molybdenum, tungsten, cobalt, nickel, chromium and other metals. The basis of all such super-alloy waste is nickel. Refractory metals in the super- alloy composition are in the form of metallized target-oriented eutectics, and due to this reason hydrometallurgical decomposition of such alloys is a difficult technological task."

Jan 1, 2008

By Frank Haehnig, Kjell-Åke Averstad, Johannes Glückert

"AbstractThe Söderströmstunneln is part of the Citybanan project that is currently under construction in the centre of Stockholm. Main part of the lot Söderströmstunneln is a 300m long immersed tunnel connecting the inner-city islands Södermalm and Riddarholmen. It consists of three tunnel elements that have been immersed in summer 2013. Since the solid bedrock is descending in that area to more then 40m depth, the tunnel elements have been placed and are permanently supported on four pile groups that have been constructed in advance. The common Swedish system of steel core piles has been used to built the pile groups. Drilling and installation of the steel cores piles in free water depth of up to 20m had to be done from a pontoon. The steel core piles are connected with underwater concrete pile caps.IntroductionCitybanan is a new 6km long double track railway tunnel running beneath central Stockholm including two new underground stations Odenplan and Stockholm City. When completed in 2017 commuter trains will have their own tracks through Stockholm, whereas the remaining railway traffic will continue to use the exisiting two tracks (see Fig. 1). This will double the capacity of the railway traffic through Stockholm. The Swedish transport administration Trafikverket is the client for this project. The design and built contract is carried out by the German contractor Züblin Spezialtiefbau GmbH together with their Swedish subsidiary Züblin Scandinavia AS.As the new Citybanan tunnel is in large parts situated below the bedrock level, it can be executed as rocktunnel in the common drill and blast method. Between the two inner-city islands Södermalm and Riddarholmen the tunnel is crossing the Söderström, an arm of the lake Mälaren. Here the bedrock is descending to a deep valley with more then 40m depth. To connect the rock tunnels between these islands a 300m long immersed concrete tunnel supported on pile foundations is currently under construction."

Jan 1, 2014

By Dean Brox

The Galore Creek Mine project is one of the newest major mining projects under development in Canada. The project is located in a very remote area of northwestern British Columbia and is being developed by NovaGold Resources and Teck-Cominco of Vancouver. The mine project comprises one of the largest and highest grade undeveloped porphyry-related gold-silver-copper deposits in North America. In order to access the mine site a new 120 km road is required including a 4.4 km mine access road tunnel. Glaciers with heavy snow pack cover approximately two-thirds of the tunnel alignment with a maximum cover of 1200 m. The size of the access road tunnel is about 50 m2 and has been designed as a large single lane road tunnel to accommodate the transport of large size mining equipment for mine start up and ongoing operations. The rock conditions along the tunnel alignment comprise very strong volcanic rocks. Key services for mining operations will be incorporated into the tunnel comprising diesel and power as well as the concentrate pipe-line. Structural portal canopies and portal houses have been incorporated into the tunnel design due to the risk of rockfalls and avalanches in the portal areas. The mine access road tunnel is a significant and critical-path component to the overall project to provide vehicular access to allow construction of the mine site. In order to meet the expected mine start up date the construction of the tunnel works have commenced prior to any other works at the mine site and will be constructed entirely by helicopter support. The tunnel works commenced in the summer of 2006 with the advanced excavation of the overburden materials at the portals. Tunnel construction from the North portal commenced in the spring of 2007. When completed, the mine access tunnel will be the longest private road tunnel in North America. The key design and constructability issues for the mine access road tunnel project are presented and discussed along with a construction status update as of late 2007.

Jan 1, 2008

Underground mine designs typically try to avoid extraction beneath streams and rivers of any significant size, especially when the overburden rock thickness between the stream bed and the mine is thin. Potential issues with mining beneath streams include excessive groundwater inflow to the mine; weak ground (roof, floor, and pillar) conditions; horizontal stress effects; as well as stream loss and other potential adverse environmental effects. However, there are times when crossing beneath a stream or river is necessary to move into a new area of mineral reserve without creating additional mine access points from the ground surface. Often, stream crossings are completed without thorough assessment, potentially resulting in increased costs, decreased safety, and, in some cases, failure to advance the mine. Selection of the most favorable location(s) to cross the stream must account for numerous factors and the associated assessment often requires a multidisciplinary approach. Stream crossing investigations often require geological, hydrogeological, geotechnical, and geophysical expertise. Phases of stream crossing investigations include desktop evaluation of maps and aerial photography, stream bed observations, drilling, detailed rock core logging, downhole geophysical surveying, hydraulic conductivity testing (packer testing), geotechnical laboratory testing, assessment, and reporting. The deliverables from a stream crossing assessment typically include geological, geotechnical, and hydrogeological characterization of potential stream crossing locations; classification of favorable and unfavorable crossing locations; recommendations for entry design and pillar sizing; and recommendations for if, and how, to conduct pre-grouting activities. Examples of technical aspects of data collection and assessment are provided based on decades of industry experience conducting stream crossing assessments in various underground mining scenarios.

Jul 28, 2020

By John R. Bradley

The object of this paper is to survey and analyze the bearing of economic nationalism, competitive sources of energy, and technologic developments on international trade in coal with especial reference to the competitive position of the leading coal-exporting countries in the Italian market, the largest in the Mediterranean region, and the Brazilian market, the second largest in Latin America. The political, economic, and financial disturbances caused mainly by the World War have resulted in an amazing situation. Especially since 1930 have conditions been complicated.

Jan 1, 1936

By R. M. Becker

THIS IS a progress report on a study of the application of statistical practice to mine and mineral sampling undertaken by the Federal Bureau of Mines to provide sound theoretical and practical data for use of the mineral engineering professions. One of the problems in mine sampling is determining the reliability of the results. For certain types of sampling data (random data) the reliability of the results can be stated mathematically. For other types of data there is no known means of quantitatively expressing reliability. In applying measures of reliability to a set of random data, some knowledge or assumption of the characteristics of the particular data is necessary. In many fields these characteristics are well known. However, in mining, where the data are in assays, these characteristics are not well known.

Jan 1, 1961