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By Robert B. Kistler, Ward C. Smith

The borate industry is one of the few sectors of the mining and mineral-processing industry which the United States still dominates. Since about 1927, the United States has supplied over half of the world's total boron and borate raw materials, and many of the chemical derivatives as well. Chiefly responsible for this record are companies producing sodium borates from two large deposits in southern California, at Boron (Kramer) and Searles Lake. The sodium borates, or products derived from borax and borax-containing brines, are the preferred borates for industry because they are soluble in water and combine readily with most other chemicals. Calcium borates (or sodium-free compounds) are required for certain end uses, but in general, nonsodium borates are used only where borax is not avail- able. During the past hundred years, the use of boron compounds throughout the world has risen from a few tons per year to the equivalent of about a million tons of B2O3. Leadership in supplying borates has shifted from country to country and from region to region during this period, generally as the result of the development of newly discovered deposits that were better in quality, more accessible, or more economically exploitable than previous sources (Table 1). Primary Products and End Uses The principal borate products offered by primary producers in the United States are listed in Table 2. In general, these products are utilized worldwide by almost all consumers, regardless of the original source of the primary borates. In the United States, the primary borates all originate in southern California. Colemanite is produced as crude or processed crude ore from the Death Valley area and is utilized by the fiber glass and ceramic industries without further treatment. Production from Searles Lake, Calif., is from brines that are processed in chemical plants where borax and other compounds are recovered and the principal borate products are produced. At Boron, Calif., the world's leading producer is mining a deposit of mineral borax and operating a chemical refinery. The mineral borax is mined together with included clay, and refined borax or "lo-mol" is one of the refinery products. The mineral and the chemical compound are identical, Na2B4O7- lOH2O. In addition to ship- ping all major refined borate products from Boron, the company ships semiprocessed ore concentrates to treatment plants elsewhere.

Jan 1, 1975

By R. C. Milici

Historical production data and reserve decline rates can be used both to predict future coal production rates and to estimate when the reserve will be depleted. Reserve estimates inferred herein from historical production data and decline rates are commonly lower than estimates made from geologic data. The latter include significant amounts of lower quality (deeper, thinner, higher sub) coal which may be mined when the better deposits are depleted.

Feb 24, 1997

By Frederick C. Rhyner

Drilled shafts have become an economical foundation choice for bridges in the northeast United States, especially when they can be constructed over water without the use of cofferdams. For the Boscawen-Canterbury Bridge over the Merrimack River in New Hampshire, an unusual design was used to avoid the use of cofferdams and avoid the need for pier caps at the waterline. This design used a pair of integral drilled shaft ? columns to form a bent type of substructure for support. Drilled shafts were 8-foot diameter, about 90 feet deep, with 16-foot long rock sockets. These are integrally constructed with 6-foot diameter reinforced concrete columns extending 37 feet from the waterline to the superstructure. Design load cases focused on lateral loads from ice flows, stream flows, wind and seismic events. Alternative analyses using different methods were made to check the design results. This paper discusses the subsurface conditions, design of the drilled shafts and columns, rebar and joint detailing issues, and construction of the drilled shafts.

Jan 1, 2004

By Andy Lemay

Vale (previously known as CVRD) is: ? The second-largest mining company by market capitalization (NYSE:RIO) ? Headquartered in Brazil ? Global workforce of over 100,000 employees including outsourced workers. Vale Inco Limited is a wholly?owned subsidiary of Vale Vale Inco Limited ? is based in Toronto, Ontario Canada: ? Operations and Projects in 20 countries ? Marketing Network extending to 40 countries ? Over 12,000 employees worldwide ? Last years sales of US $8 Billion

May 1, 2008

By Mario E. Rossi

The full economic evaluation of a mining project requires a block model that provides an estimate of the tons and grades of available resources. The model must be representative of the mineralization to be found at the time of mining for specified extraction periods and within acceptable error margins. In an operating mine, there may be a reasonable understanding and estimates of actual dilution and ore loss. This paper discusses the issue from the perspective of a project at a feasibility or preproduction level of development. Three types of dilution are discussed. Internal dilution (or change of support) is function of the spatial distribution of the mineralization and its relation to the operation?s selectivity. Geologic contact dilution is the unavoidable mixture at contacts or boundaries of material with different geologic characteristics, grades, or metallurgical performance. Operational planned and unplanned dilution should also be considered, sometimes incorporated by factoring the resource model, but more accurately by mimicking the grade control process. The resource estimation process always carries uncertainty, which is sometimes significant, and usually caused by several factors. These include quantity and quality of drill hole information; quantity and quality of geologic data; grade estimation methodology; dilution and mining recovery factors applied; etc. A key decision is to whether estimate as accurately as possible the in-situ geologic resource or to estimate the tons and grade of the material to be fed to the processing plant. The geologic modeling and grade estimation methods used are conditioned by this decision.

May 1, 2009

By A. M. R. Neiva

The WNW-ESE-trending hydrothermal veins cut alternating mica schists and quartzites of mainly Ordovician age and, to the west, a Hercynian muscovite-biotite granite. They have been prospected and developed to a depth of 300 m and reserves of 20 t Au estimated. The paragenetic sequence and chemical compositions of the ore minerals are generally similar to those at Jales to the south. Gold, electrum and aurian silver form inclusions in arsenopyrite, pyrite, galena, sphalerite, pyrrhotite and quartz and also occur in veinlets that cut these minerals. Silver has been found in gold, electrum, aurian silver, tetrahedrite, freibergite and the Ag-Pb-Sb sulphide owyheeite. Early arsenopyrite crystallised at an estimated 480 degrees C and the more common, later arsenopyrite in which Au and Ag are generally included at 430-300 degrees C. Sphalerite crystallised at 307-100 degrees C. Monoclinic pyrrhotite may have been formed by the inversion of hexagonal pyrrhotite at 248 degrees C

Jun 16, 1905

By Herly Alcázar

El presente trabajo describe el proceso de optimizacion en la fundición de precipitados de oro y plata en la refinería de la mina Pierina a través del control de los diversos parámetros que involucra dicho proceso. Para ello, se trabajó con composiciones ternarias cercanas al punto peritéctico y asi procesar adecuadamente el tipo de precipitado. Entre sus principales logros de optimización tenemos: el incremento de oro y plata, el rendimiento de los crisoles, la reducción de los costos por consumo de reactivos y el mantenimiento de la calidad del precipitado.

Sep 13, 2001

By Y Zhang, X Yi, J Deng, J Zhao, J Song

To obtain the combustion process of a coal fire, a high-temperature programmed system is used to simulate the spontaneous combustion process of fresh and weathered coals. Both fresh coal and weathered coals from Liulingou, Inner Mongolia, China, were used to examine the gas releases from constant temperature to 650°C. Moreover, gas release rate was used to calculate the characteristic temperatures. The results showed the coal samples lasted to oxidise under high temperatures, and released plenty of heat to assist self-heating. The humic acid contained inside the weathered coal went through thermal decomposition as temperature rising and generated gases. This resulted in increasing concentrations of CO, CO2, CH4, C2H4, and C2H6. Changes of CH4, C2H4, and C2H6 gases were also similar. For weathered coal, concentrations of three gases were kept in balance under low temperatures, increased rapidly with the temperature rising. After the ignition temperature, the concentration of hydrocarbon was reduced. In addition, particle size affected coal spontaneous combustion. Coal samples with less than 0.9 mm in size produced much more CO than others. This study has examined coal spontaneous combustion caused by coal weathering during mining and its impacts on self-heating and pyrolysis in the process.CITATION:Deng, J, Song, J, Zhao, J, Zhang, Y, Yi, X and Zhang, Y, 2017. Gaseous products of weathered coal during the process of spontaneous combustion, in Proceedings Australian Mine Vent Conference 2017, pp 79–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By P. Foster

Over the past decade there has been a great deal of research into the use of virtual reality (VR) and computer graphics in the mining industry. Much of this has led to developed applications including training simulators and accident reconstruction. One other area where there is considerable potential for virtual reality is that of mining ergonomics. This paper identifies those common ergonomic limitations associated with mining equipment that can be effectively modelled using VR techniques. From this, two simple models have been developed, namely (i) remote control continuous miner operation and (ii) free steered vehicle sight-lines, which demonstrate the practical use of VR in this area.

Jan 1, 2004

By J. L. Robson, C. M. Bristow

mass flow rates of particles and air (the loading ratio).

Dec 1, 1994

Remote sensing, in general, is the recording of light and heat from a planet's surface within a certain range of the electromagnetic spectrum. For the Earth, systems capable of this recording are the MultiSpectral Scanner (MSS) and SLAR. The former is the recording system used in satellite and will be discussed in the next section. SLAR stands for Side Looking Airborne Radar. This device sends invisible radar waves which illuminate the Earth's surface. The reflected waves are subsequently recorded as images. The system can operate through darkness and dense cloud cover, and is particularly suited for the study of geological structures at both large and small scale (Wayland 1976). Remote sensing techniques are now widely being made use of in mineral exploration, especially for those last remote 'sanctuaries' where geological data are meagre or non-existent. For places like Borneo, West Irian, the Amazon Basin etc. remote sensing, in the form of both satellite imagery and SLAR, is of considerable help, in fact more often than not the only help, to delineate geological provinces, geotectonic domains and meaningful lineaments. In the case of New Zealand, well made geological maps at scale 1:250 000 by the Geological Survey are available to the public and these provide useful preliminary grounds for the selection of target areas. However, even in this case LANDSAT imagery can be of aid as will be shown later.

Jan 1, 1977

By R. Y. Williams

The investigative work described in this report was undertaken by the Bureau of Mines under a cooperative agreement with the department of mining engineering of the University of Illinois and the Illinois State Geological Survey." The purpose of this agreement was to provide for a comprehensive investigation of coal-mining conditions in the State, with especial reference to the possibility of lessening waste in the mining and preparation of coal and of reducing the dangers to which miners are exposed. The Bureau of Mines paid particular attention to those phases of the investigation that were of general interest from their bearing on safety and efficiency in the coal-mining industry as a whole. Thus, it studied the occurrence of gas (methane) in the mines of the southern part of the State," tested the inflammability of the coal dust from many mines, examined the efficiency of the control of ventilating currents, and investigated the factors affecting the humidity of mine air with respect to their bearing on the occurrence of mine explosions. Following the establishment of the fact that under certain conditions dry bituminous coal dust is inflammable, there arose the problem of finding efficient methods of preventing or limiting coal-dust explosions. Experiments in the gas-and-dust gallery at the Pittsburgh testing station of the Bureau of Mines verified the fact that certain dusts that explode violently when dry are rendered inert by proper humidi- .fication of the atmosphere within the gallery, and the importance of humidity as a factor in limiting the inflammability of coal dust in a mine is demonstrated by the fact that there has never been in Illinois a dust explosion during the summer months, whereas the records show a number of dust explosions during cold weather. It is easy to see that the warm moisture-laden air that enters a mine in the summer must deposit moisture on cooling, whereas the cold and relatively dry air that enters in winter must take up moisture as it becomes heated in traveling through the mine.

Jan 1, 1914

By Renier Pereira Oliveira

Compostos orgânicos adicionados em soluções eletrolíticas podem influenciar na eficiência do eletrodepósito, no aspecto visual do material, nas fases formadas, na topografia e na dureza do revestimento. Para analisar esses parâmetros, um aço baixo carbono foi revestido com ligas Zn-Ni, a partir de três banhos distintos contendo os seguintes compostos orgânicos, além de outros reagentes: sacarina, trietilamina e ácido p-toluenossulfônico, a fim de compará-los entre si e com o banho sem composto orgânico. Para isso, utilizou-se microscópio eletrônico de varredura, espectroscopia de dispersão de raios-x e microscópio óptico confocal para análise da superfície, além de ultra-microdurômetro para determinação da dureza dinâmica do revestimento. Os resultados mostraram que os compostos orgânicos alteraram as características do depósito. Conclui-se que ocorreram alterações na eficiência catódica, na porcentagem dos elementos de Zn e Ni no revestimento, nas características de rugosidade, porosidade e dureza.

Aug 16, 2017

By A. Boominathan

The behaviour of single piles under lateral dynamic loading is very critical and the study is still a current field of research since 1950's. Though many methods have been developed analytically to estimate the dynamic lateral stiffness, very limited dynamic testing on full scale piles were carried out to study the response of piles under lateral dynamic loading. Hence, field lateral dynamic vibration tests are conducted on driven precast concrete square pile of 400mm size and driven cast in-situ concrete piles of 400mm and 500 mm diameter at a petrochemical complexes site at Haldia (India). The results of steady state and free vibrations tests are discussed herein and compared with the response of the piles estimated from PILAY.

Jan 1, 2002

By Greg Rasmussen

"Huckleberry Mines Ltd is an open pit porphyry copper-molybdenum mining operation located 120 km south of Houston, British Columbia with a 18,000 tpd milling facility. Huckleberry Mines is owned 60% by Princeton Mining Corporation, the operator, and 40% by Japanese partners.The Huckleberry deposit is one of several porphyry systems located in the Tahts a district of the intermontane belt of British Columbia. The principal economic minerals are chalcopyrite and molybdenite. The ore deposit is split into two ore deposits, the Main Zone, consisting of24,241,000 tonnes of mineable reserves grading 0.484 %Cu and 0.013 %Mo, and the East Zone, consisting of 66, 131,500 tonnes of mineable reserves grading 0.523 %Cu and 0.014 %Mo.The milling begins with gyratory crushing. This sizes the product down to 100% passing 6 inches. This product is discharged onto a stockpile by a stationary conveyor. The stockpile was designed for a capacity of 144,000 tonnes with a live capacity of 20,000 tonnes. Two apron feeders draw the ore from the bottom of the stockpile and discharge onto a SAG mill feed conveyor which in turn feeds a grinding circuit consisting of one 32' x 15' SAG mill and two 30' x 16.5' ball mills. The grinding cyclone overflow feeds bulk flotation at 55 -65% minus 200 mesh.The bulk flotation uses conventional rougher and column flotation methods to float a bulk concentrate recovering 92.6% copper on the East Zone and 95% copper on the Main Zone with 75% recovery molybdenum on both zones. The bulk concentrate feeds the bulk thickener which produces a density of 60 %solids. This in turn feeds the molybdenum circuit, which separates the copper and molybdenum, by depressing the copper then using conventional rougher and column flotation produces a copper concentrate of 27 %Cu and 0.02 %Mo, and a molybdenum concentrate containing 1.5 %Cu and 54 %Mo at 67% recovery. These concentrates are separately thickened, filtered, dried, and shipped to the smelter for processing."

Jan 1, 1998

By J. R. Thoenen

In the summer of 1937 the authors began a series of time studies of the various processes employed in' the production of crushed stone. These studies, made at quarries situated in the eastern and southeastern parts of the United States, have not been completed, but to make results available to the industry as early as possible, it was decided to publish summaries of the studies made to January 1, 1939, as a series of progress reports. The first of these dealt with power-shovel loading and was issued as Report of Investigations 3461 in September 1939. The second, issued in September 1939 as Report of Investigations 3467, dealt with quarry haulage. The present report discusses analyses of time studies of primary drilling at the same group of quarries. OBJECT Or STUDY Pressure of business problems frequently requires the entire attention of quarry management, and in consequence internal plant economies often are neglected. Also, operating officials absorbed in their local problems are prone to overlook possible economies that would attract attention immediately were they critically examining another plant. The authors felt that technical studies at a number of plants, made by impartial engineers, might disclose opportunities to reduce costs or improve efficiency in internal plant processes.

Jan 1, 1940

By R. H. Grau, S. B. Robertson, R. B. Krog

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of large-opening mines. Large-opening mine ventilation is unique for the following reasons: (1) it is challenging to keep airflow velocities high enough to effectively remove or dilute airborne contaminants, (2) large air volumes can be moved through the mines with little static pressure drop, and (3) stoppings to direct ventilation airflows are costly to construct and maintain. The research results suggest that by incorporating ventilation planning into the mine planning process, using propeller fans, developing new stopping materials and construction methods, and using long pillars to eliminate crosscuts where possible, the ventilation of large-opening mines can be significantly improved. The ventilation improvements created by incorporating these various techniques into the ventilation plan will help reduce the exposure of mine workers to airborne contaminants in underground large-opening mines.

By J. Burgess Winter

It is an honor to present the lecture in honor of Daniel C. Jackling, the developer of the technology of copper mining that we continue to use 100 years later. He made a dramatic breakthrough in the early part of this century in the development of bulk-mining methods for large, low-grade porphyry copper-sulfide ore bodies. At Magma Copper, we are particularly proud that the Jackling Award states we have "made significant contributions to technical progress." Before Jackling's time, copper mining had exploited with primitive equipment very high-grade underground ore bodies and high-grade open pits. During the 20th century, the situation changed. Three significant innovations occurred within about 10 years around the turn of the century. In 1903, Jackling's concept of large-scale mining with steam shovels and rail haulage was implemented at the Bingham Canyon mine in Utah. Eighty years after the introduction of rail haulage, the mine converted to truck haulage with large-capacity high-efficiency haul trucks and reduced the stripping ratio from 3.5:1 to less than 1:1.

Jan 1, 1995

By R. R. Oder, R. E. Jamison, E. D. Brandner

This paper presents preliminary test results obtained with a 0.38 kg/s (3000 lb-hr) beta prototype MagMill™. In processing Upper Freeport coal the beta prototype recovered 82% of the weight of the feed and 91% of the heat content while reducing the potential emissions of sulfur, kgSO2/GJ(lbSO2/MBtu), by 61%. Pyritic sulfur in the MagMill™ product was reduced by 78% compared to that in the feed. For all runs, the mill product was controlled between 70 to 80% finer than 74 µ particle size. Recoveries of mercury, arsenic, and selenium ranged from 35 to 45% of that in the feed. Power draw was reduced by 26% and mill throughput was increased by 9% compared to the pulverizer operating with no magnetic separator attached.

Jan 1, 2000

By S. J. Schatzel, W. P. Diamond

High methane emissions originating from the active face areas and from the fractured formations overlying and underlying the mined coalbed can adversely affect both safety and productivity in underground coal mines. Since ventilation alone may not be sufficient to control the methane levels in the longwall mining environment, gob gas ventholes have become a standard supplementary methane control option in many mines. As mines progress into deeper and gassier coalbeds, or as longwall panel size increases, ventilation and gob gas ventholes together may not be sufficient to maintain methane levels within statutory limits. To decrease the risk associated with methane emissions under these circumstances, in-seam horizontal methane drainage is often used to reduce the gas content of the coalbed prior to mining. Horizontal methane drainage borehole completion designs, drilling strategies, and degasification lead times may need to be adjusted for site-specific conditions due to mine design, geology, and the gas content of the coalbed. This study investigates different horizontal methane drainage borehole patterns, borehole lengths, and degasification times prior to and during panel extraction to evaluate their effectiveness in reducing methane emissions using a "dynamic" 3D reservoir modeling of a 38 1-m wide longwall panel operating in the Pittsburgh coalbed. Results of this study showed that dual and tri-lateral boreholes are more effective in decreasing emissions and in shielding the entries compared to fewer shorter, cross-panel, horizontal boreholes parallel to the longwall face. Modeling results showed that after 12 months of pre-mining methane drainage, the average longwall face emission rates can be reduced by as much as 10.3 m3/min and 6.8 m3/min using tri- and dual-lateral boreholes, respectively. It was also shown that if pre-mining methane drainage time is short, it is important to continue methane drainage during the panel extraction to maximize reductions in longwall face emissions since additional face emission reductions achieved during this period can be comparable to pre-mining degasification.