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By Charles E. Munroe

At the outset of the war the uncontrolled production and possession of explosives obviously became a serious menace to the safety of persons and property and the successful conduct of military opera- tions. Even in the years immediately preceding the entrance of the United States into the Great War explosives were employed in attempts to wreck munitions plants as at Eddystone, Pa., or to inter- rupt transportation and conveyance by demolition of munition-laden cars as at Black Tom Island, N. Y., or by attacks on ships, bridges, and viaducts. Outrages with explosives, such as that which Holt inflicted on the Senate reception room, United States Capitol, were not infrequent, and often caused serious loss of life and injury to persons as well as destruction of property. The regular manufacturers of explosives were keenly alive to this menace and early took such steps as lay within their power to meet it as is shown by the following letter:

Jan 1, 1921

By T. G. Donnelly

This final report summarizes the prototype development and testing of an air curtain respirotory protective device under Bureau of Mines Contract HO122087. The air curtain respiratory protective device, as part of a miner?s hat, provides protection for the underground mining machine operator against inhalation of dangerous amounts of respirable coal dust. Major components of the air curtain respiratory protective device are: 1) a modified miner hat incorporating an air curtain jet manifold from which the protective air curtain emanates, 2) a motor blower which supplies the air for the air curtain, 3) a filter element to remove the particulate material from the air used for the air curtain, and 4) the hoses and coupling used to duct the filtered air from the motor blower to the modified miner's hat.

Jan 1, 1973

Banks' focus in using cash flow methods can differ markedly from that of equity investors. This paper attempts to explain and describe bankers' approach by: ò outlining the fundamental difference between banks' and investors' risk / return profiles. ò describing lenders' consequent use of cash flow methods in mineral valuation. areas. explaining lenders' specific treatment of key risk Fundamental to understanding banks' appraisal of mineral projects is the appreciation that lenders have a basically different risk profile and outlook from those familiar to equity investors. Lenders do not normally participate in any project upside. The economics of lending dictate that banks can only accommodate a low probability of loan default and consequently banks' principal focus in mineral ""valuation"" is ensuring an acceptably comfortable probability of debt repayment. A simple conceptual explanation of lenders' risk / return position is outlined.

Jan 1, 1994

By G. P. Gu, B. Fang, R. W. Revie, M. Elboujdaini

Stress-corrosion cracking (SCC) tests were conducted in the near-neutral pH standard solution, NS4, and in an actual soil solution, using four-point bending at high a stress ratio and low frequency conditions very similar to those of operational pipelines. Pitting incubation appeared first and then pitting initiated and grew in both solutions although there were many more pits on the specimen tested in soil purged with 5% CO2 + 95% N2 than in the specimen tested in NS4 solution purged with the same gas. These observations show that samples in soil solution are more susceptible to pitting than those in NS4 solution. When the pit reached a critical size, the increased stress concentration around the pits, resulted in the transition to a crack.

Jan 1, 2005

By S. H. Schulz

100 YEARS AGO, on the first of August, 1877, the mining engineer Friedrich Koepe was granted the patent rights for a hoist driving ropes on the principle of friction. It was named after him: the Koepe hoist. On the occasion of this centenary, the main features of the Kcepe principle are described.

Jan 1, 1977

By Herbert H. Einstein

This report contains the documentation for 11 computer programs representing the entire computer documentation for the eight-volume report entitled "Risk Analysis for Rock Slopes in Open Pit Mines." A detailed summary of the programs is included.

Jan 1, 1979

By Esperidiana A. B. Moura, Elizabeth Carvalho L. Cardoso, Glauson Aparecido F. Machado, René R. Oliveira

Plastics global annual production exceeds 250 million tons and more than 40% of the total plastic production is used as packaging materials. In recent years polymeric materials derived from biomass have received great attention due to scarce petroleum resources and environmental concerns. PLA is one of the most extensively studied bio-based and bio-compostable aliphatic polyesters; nevertheless, high brittleness and low toughness limits its application. Blending PLA with PBAT (Poly(butylene adipate-co-terephthalate)), an aliphatic-aromatic copolyester, was the solution found due to its high toughness and biodegradability. Differences between PLA and PBAT solubility parameter values lead to the formation of immiscible blends as well as reduction in their mechanical performance besides a poor morphology; so, 5% of pre-irradiated PLA and a previous compatibilized PLA/PBAT (EcovioTM) were added to PLA/PBAT blends in order to improve miscibility phases. Investigations were accomplished on phase morphology (SEM), mechanical properties, thermal behavior and X-ray diffractions (XRD).

Mar 1, 2017

By N. A. Gokcen

This Bureau of Mines report reviews and summarizes recent studies of the rates of chlorination of aluminous resources with CO and C12 mixtures with and without COC12. No reaction mechanism could be obtained from the existing results; however, diffusional barriers in the gas and solid layers probably control the chlorination rate in thermogravimetric experiments. Fluidized beds of particles smaller than 0.1 mm appeared to show very little solid layer diffusional barrier. For optimum chlorination the particle size should probably be less than 8 mm, the calcination temperature approximately 700° C, and the chlorination temperature from 650° to 750° C. Relatively rapid chlorination with COC12 in thermogravimetric experiments was attributed partly to the simultaneous supply of reductant and chlorinator by one gas to the sample reaction site. Comparable results for chlorination of fluidized beds with COC12 are not available. Equimolar mixtures of CO and C12 produced the optimum rate of reaction. Addition to the calcine of 10 to 20 wt-pct NaCl accelerated the rate of chlorination, and addition of SiC14 to the gas mixture decreased the rate of chlorination of SiO2 drastically, but at the expense of chlorination of significant fractions of Al2O3. Further research in various areas is suggested.

Jan 1, 1983

By S. T. L. Harrison, M. Smart, C. J. Edward

Biooxidation, a biohydrometallurgical process, utilizes a mixed microbial consortium to mediate the dissolution of refractory gold-bearing ores to enhance gold recovery during cyanidation. Recognition of water as a critical resource has prompted improved water management strategies within mining and minerals processing. Bioremediated wastewater from the cyanidation tailings provides a potential water source to supplement the water required for the biooxidation circuit, reducing freshwater extraction. Gold biomining operations have typically been reluctant to recycle this wastewater due to the potential inhibitory effects of cyanide and thiocyanate (SCN-) on the microbial population. Historical process upsets suggest that the microorganisms are sensitive to SCN- concentrations as low as 1 mg/L. However, effective bioremediation processes resulting in effluents with low or negligible SCN- concentrations may allow gold biomining plants the opportunity to recycle available water. Microbial activity as well as alteration in community structure were monitored as a function of increasing SCN- concentration over the range of 0 mg/L to 5 mg/L to investigate the response of the biooxidation community to potential SCN- spikes resulting from upsets in the remediation process. Appropriate microbial growth and ferrous iron oxidation activity with a nominal shift in community structure were observed at SCN- concentrations up to 1 mg/L. Thiocyanate concentrations above 1 mg/L resulted in the complete inhibition of ferrous iron oxidation activity. This was attributed to Leptospirillum ferriphilum’s sensitivity to SCN-. Exposure to a SCN- concentration of 5 mg/L resulted in a lower cell concentration and a significant increase in growth lag time, and the absence of L. ferriphilum from the microbial population. At. caldus and Ap. cupricumulans were still present at 5 mg/L SCN-, although Ap. cupricumulans was unable to oxidise ferrous iron at this SCN- concentration. It was concluded that recycling bioremediated cyanidation tailings wastewater within the biooxidation circuit is feasible; however, to retain process performance, SCN- concentrations should not exceed 1 mg/L. Keywords: Biooxidation, thiocyanate, water recycling, community structure

Jan 1, 2020

By Randall E. Brown

Irrigation simulates a climate change so that crops can be grown that otherwise would not thrive. The abundant sunshine and warm weather of many arid regions induces a rate of growth in excess of that in cooler, moister regions. Hence, the arid part of eastern Washington, traversed by the Columbia River, is admirably suited to irrigation. The Pasco Basin lies in south-central Washington at the south end of the Columbia Basin Irrigation Project of the U.S. Bureau of Reclamation. The Basin, because it lies in the rain shadow of the Cascade Mountains, receives only 6 to 10 inches of precipitation a year with somewhat greater amounts, commonly as snow, on the higher hills. Recent extremes included 3 inches of precipitation from August 1967 to August 1968, and 12 inches in the succeeding "12 months. Most of the precipitation falls during winter. If it were to fall in summer or were evenly distributed throughout the year, evaporation rates probably would produce a true desert.

Jan 1, 1971

Silver is one of the three major metals produced from the Broken Hill mines. The accurate determination of the silver in these ores, therefore, is of economic importance.With due appreciation of the divergence of opinion of many who are interested in the subject of the determination of silver, the writer has been prompted to present the results of some recent experiments on silver losses during cupellation and conclusions from these experiments in the present paper. The losses of silver in the fire assay for this metal are due to silver retained in the slag during the fusion or scorification of the ore, and to silver volatilized from, and absorbed by the cupel during the process of cupellation.The literature describing the results of experimental work on silver losses due to the above causes is extensive, and the general conclusion of these experiments is that the silver lost in the slag is small, but that lost by cupellation is larger and more variable.The term cupellation loss in this paper refers to the total cupellation loss, no distinction being made between the absorption and volatilization losses.Volatilization loss is shown by King to be 0.5% of the total cupellation loss and, as it is generally accepted among assayers as being only a small fraction of the cupellation loss (3) (5), it will not receive further consideration in this paper.The factors causing the loss of silver by cupellation and the precautions to be obs~rved to reduce the loss in this operation are described in (1), (2), (3), (4) and (5). The...

Jan 1, 1940

By N. Chow, W. McCombe, G. Remple, J. Nikkari, L. Nightingale-Mercer

Orano Canada Inc. (Orano) operates the McClean Lake mill in northern Saskatchewan, processing high concentration uranium ore, delivered in slurry form, from the Cameco operated Cigar Lake mine. This slurry is ultimately processed into the purified uranium oxide product known as calcined yellowcake. During the calcining process, sulphate (SO42-) entrained in the yellowcake undergoes thermal decomposition into sulphur dioxide (SO2). SO2 is a colourless gas that poses health and safety risks. Since 2016, an anhydrous ammonia dosing system was successfully added to the existing Venturi particulate scrubber system to provide efficient removal of SO2 from the calciner off-gas. Within the pH controlled scrubber solution, SO2 exists in a pH dependent equilibrium with sulphite/bisulphite (SO32-/ HSO3-). The presence of a significant fraction of reduced sulphite and bisulphite in mill solutions presents a hazard in downstream circuits. Should these solutions drop in pH, either through natural oxidation or inadvertent mixing with low pH solutions, the solution equilibrium will shift from SO32-/HSO3- in favour of SO2, resulting in the evolution of SO2 gas from any liquid surfaces. In 2018, Hatch Ltd. (Hatch) and Orano implemented a design change in the calciner scrubber system. Blowdown from this system is now treated in an oxidation pre-step utilizing hydrogen peroxide (H2O2) and anhydrous ammonia (NH3) for pH control, in order to convert the residual sulphite/bisulphite present in solution to stable ammonium sulphate product. This paper will detail some of the challenges and actions undertaken to minimize SO2 risk, culminating in the recent introduction of a novel system designed to oxidize sulphite/bisulphite and prevent mobilization from the calciner scrubber solution into other mill areas where there is the potential for acidification and SO2 release.

Jan 1, 2020

By D Adhikary, M Khanal, B Poulsen, H Guo

During longwall mining, the ability to reliably estimate the height of longwall mining-induced fractures is critically important in order to effectively manage mining-induced water inflows and aquifer interference. The extent of mining-induced subsurface deformation, fracture, surface subsidence and aquifer interference is largely controlled by local lithological conditions, mining methods and mine layouts. Therefore for the purpose of quantifying mining impacts it is imperative to incorporate the local geology and mine plan parameters in a mine scale model. Two different numerical models based on 3D continuum (Finite Element Method) and 2D discrete (Discrete element method) domains, respectively, are developed to incorporate the mine site parameters of a study site in Australia. Both the models are calibrated and validated with measured mine data. The continuum numerical modelling method is used to investigate the change in permeability of the overburden strata due to underground extraction considering the full 3D nature of geology and mine layout. The discrete element modelling method is used to simulate the initiation and propagation of fractures, allowing the caving of overburden strata to be represented in a realistic manner, and the permeability enhancement of the strata overlying the goaf to be calculated from first principles. Permeability enhancement in the discrete element model is a direct function of the fractures induced in the deformation/caving process; fracture location, extent, aperture and connectedness. From the numerical modelling under the simulated condition for the mine studied here, it is predicted that the permeability of the caving zone from the goaf to five times the mining height increases by almost six orders of magnitude. In the fracture zone to approximately ten times the mining height, the change in permeability is predicted to be around two to three orders of magnitude. At the height of more than ten times the mining height the magnitude of permeability increased is predicted to be one to two orders of magnitude. CITATION:Khanal, M, Poulsen, B, Adhikary, D and Guo, H, 2018. Modelling of height of connective fractures during longwall mining, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 254–265 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

In this issue, the Bureau of Mines announces the availability of the latest of its Mineral Perspectives series: ?MP-4, mineral Industry of Western Europe." This publication describes the mineral industries of 19 Western European countries. For readers unfamiliar with this new series, reproduced below and on the two succeeding pages, is the section dealing with the mineral industries of France. Information regarding acquisition of this publication is found inside the back cover of this issue. FRANCE France is a moderately important producer of minerals, including iron ore, coal, potash, fluorspar, and uranium. In addition, France is a significant processor of imported minerals, chiefly for its own consumption. In general, it has exportable surpluses only of a little iron ore (low-grade ore exported to Luxembourg) and some nonmetallics.

Jan 1, 1977

By A. S. Dawson

"IntroductionTHE PURPOSE of this paper is to describe the results of a preliminary investigation of a method thought to be useful in interpreting geological structures in un-metamorphosed sedimentary rocks. The writer is not aware of the method having been described or investigated previously, although no thorough search of the literature has been made.The method to •be described is based on the assumption that, in argillaceous sedimentary rocks, certain ceramic properties are diagnostic for certain beds within areas of variable limits.Two ceramic properties• have been investigated: pyrometric cone equivalent (P.C.E.), and bloating characteristics of shales. The enquiry has been directed toward testing the usefulness of these properties in determining the following:A -The correlation of shale beds and, by inference, of coal seams, sandstone beds, or other such structures associated with them.B.-The location of contacts between marine and non-marine shales where lithological, palaeontological, or other evidence is lacking.Limitations of time and facilities have prevented a thorough investigation of this problem. The results given in the present paper are preliminary only. It is hoped, however, that they will occasion discussion or even lead to more thorough investigation of the method by individuals or organizations.There are, admittedly, various limitations to the proposed method. It is thought to show some promise when used in conjunction with the well-known and established methods used in stratigraphic correlation and, more particularly, when the conventional methods are not applicable."

Jan 1, 1952

By Marcello M. Veiga

Informal gold mining operations in the Amazon emit about 100 tonnes of mercury annually because of poor amalgamation practice. Lack of information and the complexity of mercury transformations hinder effective action to prevent such pollution and/or monitor its extent. In the past, mathematical equations have been formulated to deal with the correlation of natural variables and mercury in biota but often, the error range is too great to provide useful models. Projection of physico-chemical variations in an environment subjected to mercury emissions onto the extent of bioaccumulation is fraught with many uncertainties and unknowns such as internal correlations between variables and the site-specific nature of biota contamination. Often assumptions about closed systems are invalid when applied to natural environments. This work presents a heuristic approach to this problem in which amalgamation methods and natural variables are dealt with using an IF-THEN rule-based system that concludes about levels of emission and risk of bioaccumulation. The system is able to handle uncertain or vague data and yet still provide useful output. Belief in mercury oxidation or dangerous conditions are examined using Fuzzy Logic techniques and Inference Equations. These belief levels are derived from thermodynamic equilibrium data together with field observations of natural variables. This procedure can reduce the need for sophisticated analytical equipment and can provide information and diagnosis to non-technical people.

Jan 1, 1994

By J. J. Fritts, J. L. Patrick, T. L. Wright, C. O. Ensign, W. S. White, J. W. Trammell, J. C. Wright, D. J. Hathaway, R. J. Leone

The copper deposit at White Pine, Michigan, from which a little more than 5 per cent of United States primary copper currently is produced, is a large stratiform orebody, 4 to 25 feet thick and several miles across. The present ore column, containing about 1.2 per cent copper as chalcocite and native copper, is confined to the basal beds of the Nonesuch Shale. This upper Keweenawan (Upper Precambrian) formation is a distinctive gray siltstone unit, about 600 feet thick, overlying and overlain by thick red-bed sequences. All these rocks contain abundant volcanic debris, but the latest known igneous activity within 50 miles antedated the Nonesuch Shale. The rocks are unmetamorphosed and only moderately deformed, mainly by tilting and faults. Pyrite, presumably syngenetic, is the only prominent sulfide throughout most of the Nonesuch Shale. The basal beds of the formation, however, contain disseminated copper minerals instead of pyrite and constitute the cupriferous zone. On a regional scale, the top of the cupriferous zone cuts across bedding, and ranges from an inch or so above the base of the formation in some areas to more than 50 feet in others. However, within the cupriferous zone the distribution of copper shows remarkable stratigraphic control. Certain beds are copper-rich compared to the beds that lie between them and the differences persist throughout the White Pine region. Several darkgray thinly laminated beds in the lower 10 to 25 feet of the Nonesuch Shale are rich enough and sufficiently close enough together to constitute a mineable thickness where they lie within the cupriferous zone. Pyrite is the characteristic sulfide of the Nonesuch Shale as a whole. The principal sulfide mineral of the cupriferous zone at the base of the formation is chalcocite. The succession of minerals outward and upward from the center of the cupriferous zone is native copper-chalcocite-bornite-chalcopyrite- pyrite. The bornite and chalcopyrite are confined to a narrow fringe at the margin of the cupriferous zone. This pattern of mineral zones is believed to represent reaction between syngenetic pyrite and introduced copper. The main copper mineralization is independent of structure and apparently antedates deformation. Details of the geometry of the cupriferous zone indicate the possibility that copper was introduced from the underlying sandstone prior to lithification. The source of the mineralizing solutions and their copper is not known.

Jan 1, 1968

By W. R. Reed, G. W. Luxbacher

As directed by the MINER act of 2006, the NIOSH Office of Mine Health & Safety Research (OMSHR) has annually awarded contracts to enhance mine safety and health. OMSHR has a history of research that focuses on both respirable coal mine dust and respirable crystalline silica (or quartz) dust, and contracts have been awarded since 2010 in support of our intramural research efforts. In 2018, a National Academies of Science consensus study report recommended expansion of respirable dust research. As a result, beginning in 2018 through 2021, eighteen contracts were awarded focusing on this area. These contracts can be grouped in three topic areas: characterization of coal/dust, development of real time monitors, and improvement of respirable dust controls. This paper summarizes the outcomes of completed contracts and the progress of current contracts.

Mar 2, 2022

By W. M. Aubrey

The use of solid fuel in shaft furnaces to indurate iron ore pellets was originally considered a necessary evil, which the industry worked long and hard to eliminate. Since then changes have taken place in furnace design and operating practices that have led us to our suggestion that solid fuel additions could again be used. In essence, what has happened is that the developments which made it possible to operate without solid fuel have also created new operating conditions favorable to the effective use of solid fuel. Because these new conditions* were brought about in part by the desire to eliminate solid fuel and because the development was a gradual one, the industry failed to reassess its position and for years neglected the possibility of returning to solid fuel.

Jan 1, 1967

By G. E. McClelland

The Bureau of Mines investigated chemical methods for producing high- purity gold from precious-metal-bearing zinc precipitates and steel wool cathodes. Precious-metal-bearing zinc precipitates and steel wool cathodes are unrefined products from conventional cyanidation and heap leaching-cyanidation operations. The zinc precipitates contained 14,40 pct Au and 0.35 pct Ag. The precious-metal-bearing steel wool cathodes contained 20.65 pct Au and 4.84 pct Ag. The precipitates and cathodes were treated with dilute acid to solubilize the silver and/or base metals. The gold-bearing residue was leached in dilute aqua reqia to solubilize the gold. High-purity gold was precipitated from the aqua regia solution with oxalic acid, sulfurous acid, sodium bisulfite, and gaseous sulfur dioxide. The leaching-precipitation experiments recovered 99.9 pct of the gold. The gold precipitates ranged in fineness from 997 to 999 fine. The chemical refining method provides a viable technique for the smaller operator to produce high-purity gold without using pyrometallurgical refining methods.

Jan 1, 1985