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By Paul Hatmaker

This paper covers briefly the particular field of dolomite and magnesium limestone; certain uses of high-calcium limestone are mentioned only to show more clearly the limita¬ tions of the magnesian rocks. Such a comparison is helpful because magnesium carbonate is essential for some uses; for others it is immaterial; and for many its presence in an appreciable amount is objectionable. Magnesium carbonate, occurring as a rock resembling limestone or dolomite, is described in United States Bureau of Mines Information Circular 6437, Magnesite. Other com¬ pounds of magnesium are described in United States Bureau of Mines Information Circular 6406, Magnesium Compounds (Other Than Magnesite). Limestone, geologically, is a rock composed essentially of calcium carbonate; commercially, however, the term may include dolomite and magnesium limestone.

Sep 1, 1931

By George L. Richert

The Minas de Matahambre is situated on the north coast of Cuba, in the Province of Pinar del Rio, approximately 150 miles west of Havana. This nine is the only producer of copper in Cuba, and has been worked for the past 15 years. In 1921 the property was affiliated with The American Metal Co., Ltd., and has been worked by them since that time under the direction of Mr. D. D. Homer, General Manager. Extracts from P. D. Wilson's ?Preliminary report on the geology at Minas de Matahambre? have been freely used in this report.

Jan 1, 1929

By H. S. Chiang, Y. Luo, S. S. Peng

"IntroductionThe way in which the particle sizes distribute in the airborne coal dust plays an important role in the transportation of the dust in the mine air and human respiratory systems. Though the particles of a size less than 10 microns could be inhaled, the real distractive portion of the dust is that the sizes range from 1 to 5 microns since only they can reach the lungs and be retained there. Those with an equivalent diameter larger than 5 microns will settle on the membranes of the branchial tubes(1) while those with diameter less than 1 micron can either be exhaled out of the lungs or the settled quantity is so insignificant that does very little harm to the lungs. In the transportation process, the finer dust will fly farther away from the sources than the coarser ones. Thus once the fine dust is generated and becomes airborne, it will spread out to a larger area.In this paper, the coal samples collected from two longwall faces were analyzed statistically for size distribu¬tion. A mathematical model is proposed and the effects of different conditions on the dust size distribution were analyzed using the mathematical model.Sampling and Statistical AnalysesSampling Instrument and ProcedureThe instrument used in the sampling were Mine Safety Appliance (MSA) personal sampling units equipped with 10-mm nylon cyclones, pre-weighed MSA PVC filters and constant-flow pumps.Two longwall operating faces were selected for the dust sampling. The two faces were located in two coal mines ex-tracting Pittsburgh seam. The double-ended ranging-drum shearer applying the unidirectional cutting sequence was employed. The two-leg shield supports were used for face support. The width of the two faces was about 215 meters.In each of the two faces, four sampling stations were set up. The stations were located at the cross-cut immediately outby the headentry side, the 15th support (25 m), 65th support (107 m) and 111th support (182 m) from headentry T-junction, and numbered as #1, #2, #3, and #4 station, respectively (Figure 1). At each sampling station, a group of three sampling units was hung at proper position. At cross¬cut (#1) station, the units were hung about one foot under the roofline in the center of the cut (Figure 2a), and at the stations in the face, the units were position near the hydraulic legs and one foot below the support canopy (Figure 2b).One complete set of 12 samples was collected for each day. The sampling were performed for five consecutive days. All the samplings were conducted in the morning shifts. The time duration of the sampling for each day was about five hours. During that time, the shearer might complete 5 to 7 mining cycles."

Mar 1, 1989

By D. W. R. George, J. L. Stewart

Developments in the last decade, which have contributed to increased productivity and decreased coke rates in the iron blast furnace, are reviewed. Future progress in blast-furnace practice is also considered.

Jan 1, 1966

By R. F. Waters

Laboratory-scale selective volatilization methods developed by the Bureau of Mines to recover germanium and gallium concentrates from coal fly ash and phosphorus furnace flue dust are summarized. In the better experiments between 85 and 98 percent of the germanium was recovered as the lower oxide and as sulfides, and between 75 and 97 percent of the gallium was recovered as the lower oxide and as the trichloride. Grades of the condensates were inconsistent and varied between a few tenths of a percent and 8 percent, depending on the method used. In the primary extractions of germanium alone the degree of enrichment surpassed 100 to 1, and for gallium the best ratio was 30 to 1. Upgrading of condensates by vaporization retreatment and by leaching and precipitation is discussed. An appreciable degree of mechanical preconcentration by attrition scrubbing and elutriation was possible on two fly ash samples.

Jan 1, 1967

By D. L. Stevens

Following an in-depth scenario and strategic-planning exercise in 1997, Noranda's mine production goal was set at 500 kt/a (550,000 stpy) of both copper and zinc metal in five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in Noranda's program. The following steps were taken: the exploration and business development groups were combined, teams were formed to search for and respond to opportunity; geologists were coached to become more business minded and engineers were coached to become more optimistic; the company went global; clear thresholds were set, marginal properties were farmed out and other properties were fast tracked; reconnaissance exploration was focussed where there was a clear competitive advantage; and Noranda became a "flexible" partner to juniors and seniors. Is it working? A number of successes, near successes and outright failures are discussed. The main result is a much higher rate of opportunity flux, which is essential for success in the mining industry.

Jan 1, 2000

By James H. TaVoularis, William J. Wiehagen

This paper discusses the application of commercially available microcomputers for assisting trainers in the delivery and evaluation of new hire, refresher, and occupational training. A brief overview of mine training highlights major issues facing the mine training community. The use of computer-based training has a potential for reducing costs and improving the transfer of conventional training to the job.

Jan 1, 1983

By Sam Lo Grasso, Carlos Herranz Calvo, Stuart Warren, Ted Giesing, Charles Marchesano

Mott MacDonald and Project Management Advisors are providing Technical and Project Management services for San Diego County for the Courthouse Commons Project. The Courthouse Commons Project involves the redevelopment of three downtown blocks owned by San Diego County and construction of an Inmate Transfer Tunnel between the County Central Jail and the San Diego Central Court. The tunnel will be 327 feet long, crosses the San Diego Fault and is being constructed using the Sequential Excavation Method (SEM). This paper discusses the history and procure‑ ment strategy for the project, the technical aspects of the transfer tunnel and the con‑ struction progress of the tunnel to date.

Jun 13, 2021

By John N. Murphy

The past five years have seen communications techniques and hardware developed by the Bureau of Mines and its contractors increasingly brought into use in U.S. mines. The Bureau of Mines philosophy has been to help develop and introduce new hardware that goes as far as possible toward meeting the mining industry's needs. The Bureau of Nines programs are also designed to provide continuous fallout of new communications capabilities which are introduced to the mine operators as they occur. As more progress is made in meeting mine comnications needs, it is hoped that the mining industry will readily adopt the equipment and techniques that it finds most useful in meeting its individual needs. This paper reports on recent advances achieved in the development of improved nine communications systems.

Jan 1, 1976

By Paul Wellman

A computer program is presented that may be used to calculate the bare equipment cost of the major processing units for any hot potassium carbonate gas purification system. The program is designed such that, with only minor modifications, it could be used with a variety of computer systems.

Jan 1, 1968

By T Burns, P Savory

In 2013, Rio Tinto Iron Ore (RTIO) produced 251 Mt from 15 mines in Western Australia. Throughout the mines, Ore Reserve models are used for long-term and medium-term mine planning. Grade control data aids the accuracy of short-term planning. Reconciliation of models with grade control data is important for maintaining confidence in predictions from the models, understanding the limitations of the models, and identifying issues that may require further work.There are a large number of sites and models, with more than 200 professionals involved in different parts of the reconciliation process. Regular meetings of all involved and enabling effective communication are important in the reconciliation process.Reconciliation data is gathered and processed through a web-based system; Grade Block Reconciliation System. This system cuts each grade block against the required model, stores the results, and allows users to view and analyse the data. Development of this system has occurred over a number of years and all Rio Tinto Iron Ore mine geologists and resource geologists now use it as standard to report reconciliation results. The results can be viewed in many ways including by different time periods or benches. Graphing the results assists identification of trends. Centralising and standardising reconciliation has allowed easier comparison between sites. Flexibility in the system allows users to customise reports to manage issues unique to their particular site.In parallel with system development, substantial effort has been put into ensuring mining professionals get together to discuss and understand reconciliation issues. To facilitate this there are now regular sessions, including site visits. Issues are assessed on a case-by-case basis and decisions on how best to address the issues are made by the relevant stakeholders. Reconciliation reports and action plans are revised each quarter.CITATION:Burns, T and Savory, P, 2014. Reconciliation of orebody model predictions – system and people, in Proceedings Ninth International Mining Geology Conference 2014 , pp 367–376 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Monica Prezzi

"Auger cast-in-place (ACIP} piles and drilled displacement piles are being increasingly used as foundation elements for structures, particularly in projects requiring accelerated construction or involving the rehabilitation of foundations of existing, overstressed structures. Auger cast-in-place piles (also referred to as continuous-flight-auger piles) are widely used to construct the foundations of all types of structures. There are many different types of drilled displacement piles, with the installation methods varying according to the equipment used. Depending on the specific rotary piling technology used, responses ranging from those associated with non-displacement to those associated with full-displacement piles are obtained. Conventional pile design methods do not account for how the various construction techniques involved in auger piling change the soil state around the pile during installation and, hence, cannot accurately estimate the pile resistance in a consistent way. Research on this subject, identifying the different variables that must be accounted for in design and linking these variables to installation methods, is lacking. This paper describes the different piling methods available for auger cast-in-place and drilled displacement piles, the equipment used to install them and the quality control processes typically used. It also reviews some of the design methods currently used.IntroductionDeep foundations are extensively used in geotechnical engineering practice. The wide spectrum of piling methods results in a variety of pile types. Each type behaves differently, depending on the installation or construction methods. On one end of the spectrum are non-displacement piles, the classicql examples of which are bored piles or drilled · shafts. These piles are constructed by removing a cylinder of soil from the ground and replacing it with concrete and reinforcement. On the other end are full-displacement piles, such as closed-ended pipe piles or precast reinforced concrete piles, which are typically driven into the ground. Driven piles preload the materials below the toe of the pile and displace the soil surrounding the pile shaft laterally during the installation process. Therefore, displacement piles are, in general, more likely to have a stiffer response than non-displacement piles. This is true particularly in the case of sandy soils where displacement causes densification."

Jan 1, 2005

By James R. Kerr

Although metallurgical benefits of processing metals in a vacuum or reduced atmosphere have been realized for a hundred years, the problem of creating a vacuum in the range from 10-0 to 10-4 mm. of mercury in a moderately sized furnace chamber has been difficult to solve. The demand for these and lower pressures, with the advent of World War II, for separating the fission-able uranium isotope from its stable twin by the electromagnetic process, gave impetus to developing pumps capable of delivering extremely low pressures. With the release of data by the Atomic Energy Commission on methods of securing high vacuum in large equipment, steel companies took the initiative, and the growth of the vacuum-melting industry was assured. Vacuum-induction melting of steel in the United States began on a small scale in early 1945 and in 10 years grew to 60,000 pounds per month or 720,000 pounds per year. The years following 1954 showed tremendous expansion, culminating in 1958 in a capacity of more than 36 million pounds.

Jan 1, 1962

By C. W. P. Finn

INFACON is of special significance to people in South Africa who are interested in ferro-alloys, because it was in South Africa that the idea of regular international congresses on ferro-alloys was conceived and developed. INFACON 74, the first-ever such congress, was held in Johannesburg from 22nd to 26th April, 1974, being organized by the South African Institute of Mining and Metallurgy, the National Institute for Metallurgy, and the Ferro Alloy Producers' Association of South Africa. Design Awards The Design Institute is inviting entries for the 1981 Shell Design Awards. Any product that falls into the three categories shown below, and that was designed in South Africa and is in production, is eligible for an award. Since their inception in 1970, the Shell Design Awards

Jan 1, 1981

By Louis C. Srichta

The rapid depletion of known high-grade ore deposits of the Tri-State district and the recognized need for development of additional reserves, together with increased interest in open-pit mining of low-grade zinc-lead ores led to Bureau of Mines examination of several abandoned mining areas for possible deposits adapted to strip mining. Examination of the North Empire tract in Cherokee County, suggested that mineralized zones contiguous to previously mined 2e deposits presented probabilities of meeting the requirements for an open-pit mine - hence the tract was selected for further investigation by churn drilling. The zinc-lead deposit on the property is in a sink-hole structure that has been subjected to intense deformation and silicification. Numerous shafts, mine dumps, and surface caves are evidences of exploitation of an extensive area. The reported active mining period was 1895 to 1905. No production records are available, but it is generally stated locally that the value of the mill products exceeded $2,000,000 which represents considerable production, considering the low metal prices of that epoch.

Jan 1, 1950

By M. Onifade, O. S. Otuogbai, A. F. Mulaba-Bafubiandi, O. D. Eniowo, H. Grobler

Artisanal and small-scale miners in Nigeria struggle to attract formal financing to upgrade their operations to a more sustainable form of small-scale mining operation. Literature shows that for an investment to attract formal sources of financing; the business must be considered creditworthy by potential lenders. This means that the credit risks associated with the investment must be bearable for the potential lender. This study looks at how artisanal and small-scale miners can attract formal funding, which will help them take the leap from artisanal state to a form of sustainable small-scale mining operation. This study evaluates the creditworthiness of artisanal and small-scale mining operators using key credit risk parameters identified in the literature and through primary investigation. A quantitative study is conducted on a sample of 100 artisanal and small-scale miner establishments in Nigeria to evaluate the effect of these identified credit risk parameters on creditworthiness. It is shown in this study that being a member of a mining cooperative society, which is a form of social collateral, best improves the chances of access to formal financing for miners within the sample group. This underpins the role of social collateral, in both the formal and informal economy, and its influence in improving the creditworthiness of a typical artisanal and small-scale miner.

Jul 23, 2025

By Rodney R. Koch

The phys ica l properties of gold should faci li tate its detection. However, the average concentration of gold in the ea rth's cru st precl udes the ability of geophys ical methods to detect the metal directly. In order to effectively pursue geophys ical detection and location of gold mineralization there must also be geological input - i.e. a model. This will lead to the selection of the appropriate geophy ical techn ique(s) in the fo llow-up programs. Interpretation of the fie ld survey data is of con iderable importance in expl oration geophys ics. Analytical techniques such as cont inuation, fi ltering, and spectral analys is, are now routinely empl oyed in the analys is of survey data to aid the interpretation process. The uccessful application of geophysical methods and the use processing techniques is demonstrated by two recent Saskatchewan discoveries. The first, the Star Lake 21 Zone, with reserves of 230,000 tons grading bener than 17.14 git Au associated with a disseminated sulphide quartz-bearing shear zone yielded geophysical anomalies that were distinctive, obvious, and would have lead directly to its discovery. The econd , the Laurel Lake Prospect, with ore grade intersections of 28.0I git Au and 52 .46 git Ag· over 5.49 m, resulted in numerous geophysical anomalies. However, none of these anomalies demonstrated association with the mineralization until processed results indicated that structural features crosscuning regional trends were important cont rol mechanisms for the mineral ization.

Jan 1, 1986

By Robert K. Linn

The New ldria Mining District is in the southern part of the Diablo mountains of the California Coast Range, 140 miles southeast of San Francisco. The district, noted primarily for quicksilver, also has become important recently as a producer of short-fiber chrysotile asbestos. Between 1853 and 1966, the New Idria district produced 568,092 flasks of quicksilver valued at about $55,600,000, 99 per cent of which was recovered from one deposit, the New Idria mine. In 1944, the district was ranked third in all-time production of North American quicksilver districts, and, since that time, the New Idria mine produced an additional 129,045 flasks, placing the district and the New Idria mine second in all-time production. The major structure of the region is the northwest-trending Coalinga anticline consisting of an asymmetric dome of sedimentary beds ranging in age from Jurassic to Quaternary and marked at its northwest end by an oval body of sheared serpentine 14 miles long by 4 miles wide. The serpentine core, rimmed by Franciscan sandstone of probable Jurassic age, was uplifted in stages between Jurassic and Quaternary time and was intruded along a ring of faults into beds of the Panoche Formation of upper Cretaceous age. The core of serpentine and Franciscan rocks is the locus of about 20 quicksilver mines that rim the faultbounded core and lie within the serpentine mass. The host rock of the most productive deposits is altered Panoche shale and sandstone that lies intermittently along the perimeter of the core. Deposits of the New Idria group of mines and those of a few other small mines lie along the northeast contact in the footwall of the New ldria thrust fault, and a few others occur on steep normal faults around the south and southwest. The chief ore mineral in all quicksilver mines is cinnabar, but minor amounts of metacinnabar and native mercury are found in some of the mines. Ore shoots were deposited in fracture zones and stockworks in altered Panoche shale and sandstone and in definite fissure veins in Franciscan sandstone. Rocks made highly amenable to fracturing by hydrothermal alteration were fractured extensively by late faults. The resulting fracture zones, located along the late faults and at changes in strike or dip of the hanging wall or footwall, are the principal controls of most ore shoots. The largest and richest ore shoots are those of the New Idria mine. The major ore bodies occur in fractured shale and sandstone beneath the New ldria thrust fault at its junction with major tear faults.

Jan 1, 1968

By Matthew Geary, Stephen J. Marino, Jordan A. Schreiner

"INTRODUCTION Project Overview The Southeast Collector (SeC) is a new 15km long 3.0m internal diameter wastewater tunnel designed by Hatch Mott MacDonald (HMM) that twins the existing 2.6m diameter York-Durham Sewage System (YDSS) tunnel. Both sewage tunnels are located north of the City of Toronto in Ontario, Canada. The SeC provides much needed conveyance capacity for the rapidly growing York Region population, supporting development until 2036 and increasing sewage system security (Hatch Mott MacDonald and AECOM 2011). Construction of the SeC will also permit flows of the twinned section of the YDSS to be bypassed in order to clean, inspect and carry out any essential maintenance within the YDSS tunnel. Although owned and operated by York Region, the SeC spans two regional municipalities beginning upstream from the intersection of Ninth Line and Rouge Bank Drive in the City of Markham in York Region to the downstream Finch Avenue and Valley Farm Road intersection in the City of Pickering in Durham Region. See Figure 1 for the SeC and YDSS alignment. The project includes 19 shafts and chambers with depths ranging from 8 to 48m in addition to seven facilities supporting the operation and maintenance of the sewer. The construction contract was awarded to Strabag Inc. in July 2011 for $291M CAD. Construction Management services were provided by a joint venture team of Hatch Mott MacDonald and AECOM. Existing York-Durham Sewage System The YDSS tunnel was completed in 1979 and was constructed using an open shielded TBM with ribs and lagging temporary support, followed by installation of a 380mm thick unreinforced cast-in-place (CIP) concrete final lining. The YDSS sewer system has numerous connections that accumulate flows from various urban areas within York Region. The section of the YDSS twinned by the SeC flows under gravity conditions and had been putting a strain on the municipality’s potential for population and development growth having reached its maximum capacity of 420 ML/d. According to the York Region’s Water and Wastewater Master Plan, the existing YDSS would not have been able to handle wet weather flows past 2016 (Genivar and XCG Consultants 2009). The dependability of this section of the YDSS is also of concern because it is the main and critical connection between the sewer systems upstream and the downstream Duffin Creek Water Pollution Control Plant (WPCP)."

Jan 1, 2016

By William W. Odell

Certain gas-making processes are in use in Europe, particularly in Germany, which differ radically from those in common use in America. A number of them are of particular interest because they are different. The questions naturally arise: Are any of them applicable to the making of gas in this country and, if so, with what particular type of solid fuel? It is a fact that some of them were developed with consideration of a particular set of conditions and for the utilization of solid fuels available in Germany. The latter fuels, in certain characteristics, are unlike the high-rank fuels commonly used for making gas in the United States; therefore, in attempting to evaluate the various foreign- developed processes with regard to usefulness here, one must give attention to the particular conditions that will prevail in any specified case and also the characteristics and requirements of the process and generator under considera- tion. Three of the processes that were developed and put into commercial operation in Germany, and which have some characteristics in common, are con- sidered in particular in this publication; they are: 1. Lurgi pressure gasification process. 2. Winkler process. 3. The Leuna slagging-type producer-gas process. Each of these processes requires steam and oxygen as gas-maiding fluids. For a number of years, oxygen, has been used in a relatively pure state,. along with steam, in making gas in Germany, and many of the difficulties initi-. ally encountered have been overcome. Although it appears that oxygen recovered from air was first used in this manner as a method of utilizing a byproduct in a plant that used the nitrogen complement in the manufacture of ammonia; more recently, the oxygen was made particularly for the purpose. The fuels - brown coal or lignite used in processes 1 and 2 were not suitable for use in the older and commonly used intermittent-type water-gas generators, and it was necessary, therefore, to devise a different process for gasifying them. A gas of higher heating value than producer gas, was desired, and the use of oxygen (not air) along with steam made possible the production of the desired gas without nitrogen dilution, which characterizes producer gas. Operating data presented herein are based upon observations by, members of the Technical Oil Mission at plants in Germany, on records, and on information vocally given to members of the lässion, including the author, while visiting those plants, and they are believed to be reasonably correct; however, certain hasic observations, comparisons, and conclusions are. made by the author.

Nov 1, 1947