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By P. M. Daling

This report, sponsored by the U.S. Bureau of mines, presents the results of an examination of available safety assessment methods and their applicability to the mining industry. Standard safety analysis procedures were evaluated for relevance to the mining industry and mire operators' needs. The major safety concerns and needs of mine operators were identified through telephone contacts and a visit to a mine site. Safety assessment methods recommended for use by the mining Industry were also investigated for potential adaptability to a user-interactive computer system. Several methods were determined to be Immediately transferrable to the mining industry; these techniques are described in a user's handbook produced as part of this project. The handbook gives detailed instructions on appropriate application and utilization of these methods. Other techniques will require further development before they can be effectively transferred to the mining Industry. These methods, their advantages, disadvantages and resource requirements are described in the final project report. Recommended system safety analysis techniques facilitate an evaluation of total mine system safety and a determination of safety-related interactions among systems within a mine. The application of these methods to the mining industry could result In reductions in both the frequency and the consequences of mine accidents.

Jan 1, 1983

By John C. Machisak

INJURY experience and employment data for the nonmetal mining industry in the United States are presented for the calendar year 1958. Statistical tables 6 to 12 give detailed information on injuries and employment at nonmetal mines. Data for nonmetal mines are presented separately from those for nonmetal mills, tables 23 29. The Bureau is authorized to send questionnaires to the nonmetal industry for their voluntary submission on of injury and employment experience at their operations. As this information contributes to the promotion of safety in the nonmetal mining industry, every effort has been made to make these questionnaires as complete as possible.

Jan 1, 1962

By M. G. Dellow, D. W. Hendriks

"In early 1988 the decision was made by Noranda Minerals Inc. to install pressure filters at the GECO mill to replace the vacuum disk filters and bunker-C fired rotary kiln dryers. Two filters were installed, one for copper concentrate and one for zinc concentrate. Completion of the project was scheduled for the third quarter of 1989. The filters were made operational in October 1989. Some work remains to be done yet on loadout conveyors for total project completion. Capital expenditures for the project have been approximately $2,700,000 to date. The paper describes the selection criteria for the filter, the installation, startup and associated problems.1. INTRODUCTIONThe filter model chosen for the project was the Verti-Press model VP-50-6(7) (Figures1 ,2 and 3) by Filtra Systems of Farmington Michigan, USA. The decision to purchase the Filtra Systems filter was based on gaining familiarity with a different, mechanically simpler pressure filter than the Larox design and to a lesser extent a necessity for repairs to the the disc filter, rotary kiln dryer system used at the GECO operation for its' copper and zinc concentrates. The fact that it is manufactured in North America was an important consideration. The same basic principles of pressure filtration as the Larox machine are used but the implementation is quite different and somewhat simplified with some interesting innovations. 2 filters were installed to allow direct and immediate comparison of the same machine on both fine and coarse materials. Copper concentrate is reground for cleaning on the flotation circuit while zinc is not. Screen analysis of composited samples of concentrates for 1988 indicated that expected copper concentrate would be approximately 66% minus 400 mesh and zinc 50% minus 400 mesh (Tables 1 & 2).The filter is composed of six horizontal chamber module layered vertically and held together in a frame by 1 O large bolts; torqued down to 4000 ft-lbs. 6 individual belts are used; each with its own drive system. The belts themselves are of a 3 piece design with a filter cloth portion, a support belt and a rubberized intermediate portion. They are held together with steel clipper lacings. A basic description (1) of the filter operation is as follows. ""The horizontal filler chamber is closed by hydraulically pressurizing seals across each end of the filter chamber to 200 psi. The feed pump then pumps slurry into the filter chamber. Suspended solids are retained on the filter belt and the filtered solution drains into a lower drip tray and flows from the filter by gravity. At the end of the filtration or feed cycle, a rubber diaphragm in the filter chamber is pressurized hydraulically to 100 psi pressure. This removes all free liquid from the filter chamber and the filter cake. After the diaphragms are retracted the filter cake is blown with compressed air to remove any residual cake moisture. The seals are then retracted and the belt is advanced to discharge the filter cakes. During the cake discharge the belts are washed with a spray header located at the drive end of the filter. The belt assemblies move one (1) complete revolution during the cake discharge cycle. The cycle automatically repeats until the filter is shut down by the operator."

Jan 1, 1990

By W. W. Aljoe

The use of protective canopies can result in canopy roofing and/or serious restrictions to operator comfort and vision. To document this experience, BCR conducted a field study of cab and canopy design and application which resulted in a catalog of 164 canopy designs and an analysis of field data which showed no simple relationship between working height and canopy-related problems. The relationship also involves (1) machine frame height, (2) mine floor undulations, (3) operator compartment dimensions, (4) canopy design and location on the machine. Data analysis indicates (1) present technology does not always permit successful application of canopies in working heights below 42 inches, and (2) development of satisfactory low-coal canopies is doubtful. The basic conclusion of the study is that future R&D studies should be directed at development of alternative protection systems and remote mining methods.

Jan 1, 1981

By Jochen Franke, Derek D. Lichti

"This paper gives a brief introduction and presents recent enhancements in the MillMapper technology developed for thickness gauging and condition monitoring of liners in grinding mills used for mineral comminution. It also introduces the recent expansion of MillMapper functionality aimed at mill operational optimization. MillMapper uses calibrated laser scanner data captured inside a mill to determine thickness at several million points on all liner surfaces at feed, shell, and discharge ends with millimeter accuracy. Data capture takes nominally 5 minutes, hence interruption to mill operation is negligible.The paper is structured as follows. First, a review of the technology and discussion of recentlyimplemented innovations such as liner change out forecasting, automatic ball charge volume and weight measurement, and automatic mill liner volume/weight measurement for mill operational control or load cell calibration are presented. Combined weight information provides control over load related issues such as load fill levels for relining, or start-up load after reline. Feature descriptions are followed by a listing of the numerous advantages over existing techniques and the benefits to operations. Results from the application of MillMapper are presented throughout.INTRODUCTIONThe need for thickness gauging of liners of grinding mills used for mineral comminution is well known but the task is rarely completed to a satisfactory standard. Liner failure resulting from excessive wear can have expensive consequences. Furthermore, mill performance as well as liner wear are known to be correlated to lifter bar geometry (Napier-Munn et al., 1999; Rajamanni et al., 2005). At present, the following techniques are routinely used to gauge the thickness of mill liners:1. Visual inspection;2. Ultrasonic thickness gauging (for steel liners); and3. Physical inspection (e.g. nail inserted in rubber liners)"

Jan 1, 2008

Syncrude Canada produces a large part of Canada’s crude oil supply. The company processes about 225,000 bbl/day. The oil produced is used for jet and automobile fuel, home heating oil, plastics and other consumer synthetics. Crude oil is produced through a process of mining, extracting and upgrading bitumen. A rich supply of bitumen is contained in the Athabasca oil sands deposit in northern Alberta. Tailings from the bitumen processing are sent to a settling basin.

Jan 1, 2000

By Vance G. Leak

A technique for recovering copper and steel from metallic scrap has been developed by the Bureau of Mines based on preferential melting in molten salt baths at 1,150° to 1,250° C, The molten salt, preferably barium chloride or calcium chloride, both minimizes oxidation of the metals and promotes heat transfer. Cleanest separations (0.01 percent copper remaining in iron) have been achieved by pretreatment (dipping or spraying) with sodium sulphate or sodium silicate, which alters and coats the surface of the iron to inhibit the alloying or brazing with copper. An economic evaluation of the process was carried out on six combinations of sweating media and inhibiting reagents. On the basis of the postulated model, a cost of about $0.20 per pound of copper recovered has been determined for the sweating treatment operation.

Jan 1, 1973

By A. K. Andersen

One of the prime examples of the versatility of the MARCONAFLO system, which is a body of technology comprising the means to handle, store, load, transport, discharge and reclaim mineral commodities in slurry form, is the direct application of this process to leaching ores. The initial approach was to provide a much improved materials handling system for the transport of copper ores; however, an extensive development program, inclusive of prototype and pilot plant tests, has established that a new leaching concept is possible with this system. Data are presented from the leaching operation of a 25 TPD pilot plant utilizing a copper-oxide ore, mainly chrysocolla. This pilot plant was designed to incorporate true countercurrent flow where the ore is actually in motion, as contrary to vat leaching operations, and the ore being successfully leached is fine crushed ore (3/8-inch x o), contrary to agitation leach circuits. Extractions in excess of 85% of the soluble values are common with only 15 hours of retention time in the MARCONAFLO leaching system.

Jan 1, 1975

By R. W. Armstrong, P. C. Jindal

The hardness dependence on grain size for polycrys-talline cartridge brass and a leaded brass has been measured by Brine11 and Rockwell B testing. In each case, the hardness, H, depends on the average grain diameter, 1, according to: H =Ho + kHl-1/2 where Ho and kH are experimental constants. Diamond pyramid hardness values have also been measured as a function of the indentation size and grain size to give additional information on the nature of the hardness test and the dependence of hardness on micro-structure. The hardness of polycrystalline brass depends on its grain size. Bassett and Davis' demonstrated this as early as 1919 by making Brinell hardness measurements on cartridge brass. Since then, the hardness of this type of material has been measured as a function of grain size by making Rockwell,2'3 Vickers,4 and Brinell5 tests. he hardness dependence on grain size has also been measured for other materials. Angus and summers6 investigated the grain size dependence of the Brinell hardness of polycrystalline copper and a Cu-4.5 pct Sn bronze. In other studies, nickel,? Armco iron,Big an Fe-0.07 pct C alloy,I0 and an 0.39 pct C-12.45 pct Cr stainless steel" have been investigated. In some of the preceding cases, the hardness results have been analyzed to show that the hardness varies with the average grain diameter, 1, according to an l-l\4, l-1/4 or I-2 dependence,11-13 The studies of the influence of grain size on hardness have not been based on any theoretical model. This may be because the hardness of a material is itself a complicated property. However, attempts have been made to correlate, experimentally and theoretically, the hardness of a material with its unidirectional stress-strain behavior.14-l6 On this basis, Hall" proposed that the polycrystal hardness dependence on grain size might follow directly from the Hall-Petch18,19 relation for the grain size dependence of the yield stress. Thus, the hardness-grain size relation was given as: H = Ho + kHl-1/2 [1] where Ho and kH were taken as experimental constants. The relation was applied to the measurements on brass,' copper,6 bronze,= and Armco iron.' More recently, this relation was shown by Armstrong and jindal20 to adequately describe the measurements on cartridge brass made by Bassett and Davis' and Babyak and Rhines.5 In this case, the relationship was taken a step further by independently relating the values of Ho and kH to the values of oyand ky, previously reported by Armstrong, Codd, Douthwaite, and petch21 from measurements of the yield stress dependence on grain size for this type of material. In the present investigation, new Brinell and Rockwell B hardness measurements have been made as a function of grain size for a cartridge brass and a leaded brass. In addition, diamond pyramid hardness values were measured as a function of the indentation size. All these results are applied to a further analysis of the hardness dependence on grain size. MATERIALS AND EXPERIMENTAL METHODS Cartridge brass and a leaded brass were selected for this investigation for two main reasons: it was anticipated 1) that these materials could be cold-worked and recrystallized to a wide range in grain size and 2) that the results to be obtained on these typical industrial materials could be usefully compared with previous investigations. The chemical analyses of the actual materials which were employed are given in Table I. The as-received 1/2- and 3/4-in.-thick plates were given various reductions in thickness by cold rolling. The rolled material was heat-treated at various temperatures between 330" and 850°C for differing time periods from 5 min to 9 hr to achieve a variation in the average grain diameter between 0.0339 and 0.000543 cm.22 During heat treatment, the brass was protected from zinc loss by packing it in chips or foils of the same composition material. Reasonably equi-axed grain structures were obtained in each case. The metallurgical grain sizes of the specimens were determined from measurements of the average linear intercept on a random line. Annealing twin interfaces were not counted along with grain boundaries. The

Jan 1, 1970

By Walter B. Lenhart

This paper is one of a series on milling methods and costs being. published by the Bureau of Mines. The milling practices and special problems relating to grinding, tailings disposal, and choice of a treatment process at the Cardinal mill are discussed. The property of the Cardinal Gold Mining Co. is about 18 miles southwest of the town of Bishop, Inyo County, Calif., at an altitude of approximately 8,500 feet. The camp has been designated Bishop Creek by the postal authorities. The property comprises 33 mining claims, including fractions and millsite in sections 19, 20, 29, and 30, T. 8 S., R. 31 E. These claims are located in a general way along the strike of a band of quartzite.

Jan 1, 1938

By J. E. Murphy

The high-purity thorium metal was prepared by the Bureau of Mines from electrolytically produced thorium alloys. The thorium-chromium and thorium-manganese alloys were separated into the component elements by vacuum distillation. Chromium and manganese impurities remaining in the thorium metal after distillation at 1,850° C were <0.005 weight-percent. Removal of volatile impurities such as aluminum, calcium, magnesium, and lead was also accomplished.

Jan 1, 1969

By Malcolm Ross

The Reserve Mining Co., in the processing of taconite iron ore quarried from the Peter Mitchell Pit, deposited the finely crushed waste rock into Lake Superior near Silver Bay Minnesota. In the early 1970s The U.S. Environmental Protection agency filed a lawsuit against Reserve Mining Co., asking the court to force the company to stop dumping into the lake. On April 20, 1974, after a lengthy court battle, the U.S. District Court concluded that the Reserve Mining discharge into Lake Superior violated federal and state pollution laws and thus ordered Reserve Mining Co., to halt the lake disposal of taconite tailings. At the time many feared that some of the mineral particles contained in the tailings (alleged to be asbestos or asbestos-like) would cause human health problems. This Conference was thus convened to readdress the problem of the mineral content of the Biwabik Iron Formation and to whether any minerals contained in the ore could cause human disease. The four papers given in this session address the nature of the mineral particles in the taconite rock, the definition of the term ??asbestos?? and the history of the legal controversy over the possible health effects of certain mineral particles contained in the Biwabik iron range ores. Paper 1?Geology of the Biwabik Iron Formation and Duluth Complex Mark A. Jirsa, James D. Miller, Jr., G.B. Morey The Biwabik Iron Formation was a principal source of ore for the American steel industry during the 20th Century. The unaltered iron deposits, called taconite, contain approximately 30% iron and 50% SiO2. About 75% of the iron in taconite resides in the mineral magnetite, the remainder is largely in iron carbonate and several iron-silicate minerals.

Jan 1, 2007

By Claude W. Sill

In the course of a series of investigations on vanadium deposits of the western United States, the Bureau of Mines collected many hundreds of samples for chemical analysis. As uranium is often associated with these vanadium minerals, they were also analyzed for uranium, which was pound to be absent in a large percentage of the samples. Since the usual methods for determining uranium are laborious and time-consuming it is very desirable to have some simple qualitative test that can be applied prior to a quantitative analysis to determine whether uranium is present or absent and thus save the time and expense of applying the quantitative analysis to the large proportion of samples containing no uranium. To be acceptable, the test should be specific for cranium, sensitive enough to detect small amounts of uranium, and. simple enough to make it worthwhile to apply. The available methods for detecting uranium lacked one or more of the desired characteristics. Eventually, however, a method was worked out that satisfied all the requirements. This method is probably more specific and sensitive than the usual qualitative methods for uranium, and its simplicity and speed of application make it ideal for testing samples prior to quantitative analysis.

Jan 1, 1945

By S G. Walters

The minerals industry is facing a productivity and investment crisis. The ‘Millennium Super Cycle’ from 2003–2011 was an unprecedented period of growth and investment resulting in increased throughput and development of lower grade resources to meet demand. During the boom quantity became more important than quality with throughput the key metric. This was accompanied by a general trend of decreasing feed grades across all commodities that was offset with higher production volumes.Current industry perception is that feed grade depletion is an unavoidable consequence of ore deposit geology and mass mining technologies for increasingly mature mining operations. In typical crush-grind-float operations value recovery only takes place at ~1–200 micron particle size during flotation, ie 3–4 orders of magnitude size reduction compared to primary feed. For increasingly low-grade deposits the cost of energy and capital intensity required to process and reject low value material at micron scale drives poor productivity. An alternative is to deploy a range of coarse (~10–100 mm) separation and rejection technologies. Grade Engineering&#174; is an integrated approach to coarse rejection that matches a suite of separation technologies to ore specific characteristics and compares the net value of rejecting low value components in current feed streams to existing mine plans.Coarse rejection can be used on size distributions ranging from run-of-mine (ROM) to semi-autogenous grinding (SAG) discharge. Grade Engineering&#174; is based on five rock based ‘levers’ linked to combinations of screening, sensor-based sorting and heavy media separation. These involve exploitation of preferential grade deportment to specific size fractions during breakage: differential blasting to condition grade by size at bench scale; sensor based sorting at truck and conveyor scale; and differential particle density.Grade Engineering&#174; is being developed and implemented by a consortium of over 30 mining companies, equipment suppliers and research organisations. Emerging results from collaborative site activities demonstrate potential for generating significant value, which can reverse the trend of declining productivity due to feed grade depletion.CITATION:Walters, S G, 2017. Driving productivity by increasing feed quality through application of innovative Grade Engineering&#174; technologies, in Proceedings Tenth International Mining Geology Conference 2017, pp 263–274 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By X. W. Pan

It has been found that the MnO content of a slag decreases sharply when direct current is applied to a 1T1£tal-Slagsystem consisting of liquid Mn-Si-Ccsat metals and MnO-SiO2-CaO-AI203 slag in graphite crucibles. This paper reports a preliminary investigation into the electrochemical effects of direct current on the metal-slag system, the silicon content of the metals, and the MnO content of the slag. The results show that, when a direct current of 7 A is maintained, the MnO content of a metal containing 10 to 11 per cent silicon by weight is reduced rapidly from 26,5 to 17,2 per cent by weight. This reduction seems to proceed further when the process is continued. When the direct current and the voltage are kept constant at TA and 4 V respectively, the MnO content of a metal containing 1 to 2 per cent silicon by weight is reduced to 1 from 25 per cent by weight, which results in a manganese yield of 96 per cent.

Jan 1, 1995

By Neil and Associates

Seismic tomography is one of several additions to the suite of geotechnical engineering tools for use in various underground rock and mineral geologic structures. Seismic tomography is a method for reconstructing a cross section of an object based on attributes of seismic energy that have been transmitted through the object. The in-seam seismic tomogram provides a dataset that can be graphically portrayed in a color-coded format that is then used to infer relative stress concentration (Fig. 1). During the past several years, the US Bureau of Mines (USBM) at its Denver, CO and Twin Cities Research Centers in Minnesota funded several innovative hardware and software developments. These were directed toward use of in-seam seismic tomography for underground geologic strata evaluations. These preliminary investigations have matured into well-defined and field-proven technical advances for improving ground-control decision making in the mining industry.

Jan 1, 1996

Jan 1, 1962

"For effective steel refining in the ladle (secondary steelmaking) the amount of steelmaking slag that is transferred from primary steelmaking must be limited, because the steelmaking slag contains iron oxide, manganese oxide, and phosphorus oxide. Adverse effects of slag carry-over include increased consumption of deoxidizers, phosphorus pick-up by the steel, and increased ladle refractory wear. Infrared imaging at longer wavelengths is an effective non-contact method to detect slag in the tapping stream. Various devices are used to shut off the tapping stream rapidly. These include slag darts, pneumatic slag stoppers, and slide gates for steelmaking converters, and eccentric bottom tapping for electric arc furnaces. IntroductionOxygen converters and electric arc furnaces are used for primary steelmaking. For both process types, the product (liquid crude steel) has a similar composition: largely liquid iron, with around 800–1000 parts per million (ppm, by mass) dissolved oxygen and low but significant concentrations of carbon, nitrogen, and phosphorus. The steel is tapped into a ladle, which serves as the refining vessel to adjust the final steel composition and temperature before casting.Some steelmaking slag is inevitably tapped with the liquid steel. The mass of steelmaking slag tapped with the steel is termed ‘slag carry-over’. Controlling and limiting slag carry-over from steelmaking is a primary requirement for clean steel production (Fandrich, Lüngen, and Wuppermann, 2008). Steel cleanliness refers to limiting the concentrations of dissolved impurities (such as nitrogen, oxygen, phosphorus, and sulphur) and of nonmetallic inclusions (oxides, sulphides, and nitrides) in liquid steel and in the final solid steel product. Of these, the strongest effect of slag carry-over is on the content of dissolved phosphorus in the liquid steel"

Jun 1, 2019

The objective in control blasting is to reduce overbreak to control the final pit wall slope, shaft, drift, ditch, bench, etc. to the final planned excavation limit.

Jan 1, 1991

By W. B. Berwald

The United States Bureau of Mines, in cooperation with the Natural Gas Department of the American Gras association, has been studying actively for the past several years the problem of the flow of natural gas through high-pressure transmission lines. Numerous data on gas flow through pipe lines under many conditions of operation have been obtained by carefully conducted tests, and these data, together with all other available information, have been analyzed carefully to secure practical facts for the use of operators in designing pipe lines and determining the effects of different operating conditions on pipe-line capacities. The first procedure in initiating; this problem was to review, compile, and analyze all of the existing data on the flow of natural gas through pipe lines. Actual data applicable to pipe and operating conditions normally used in the transmission of natural gas were meager, and the several pipe line flow formulas developed by different investigators gave widely varying; results when applied to problems of pipe-line design. Therefore, further experimental work under conditions comparable to those found in transmitting natural gas was essential before any definite recommendations could be made.

Jan 1, 1931