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By Charles H. Grant

Blast design methods generally deal with end points or limits of design such as spacing, burden, stemming depth, etc. Even cratering design deals with limits defined as a function of energy decay to a limit. Although this crater method provides a better method than trial and error judgment it does not take into consideration the distribution of energy throughout the material to be blasted. This paper deals with a method of examining this distribution with the aid of a computer and how changes in blast design affect this distribution. First I would like to explain the equation used to develop the energy summations throughout the blast. As shown in Figure I a series of drill holes are drilled to various depths starting by placing the explosive charge on the surface and then at various depths until a sufficient depth of hole is reached to exceed the ability of the explosive energy effect to reach the surface of the ground. All volumes of explosive are the same, all holes contain the same explosive and the drill hole diameter is the same.

Jan 1, 1980

By Aaron Jones, Guy Reed, Russell Frith

"In 2017, one of the international authorities on coal bursts, Dr. Chris Mark, published a paper entitled “Coal Bursts that Occur during Development: A Rock Mechanics Enigma,” in which several relevant technical issues were identified, the most pertinent being:i.whilst development coal bursts are commonly associated with geological faults, understanding which specific faults result in burst-prone development mining conditions and why, remains undefined.ii.conventional wisdom in relation to strong roof and floor geology of the coal seam might be limiting, based on certain burst examples in Colorado.iii. development coal bursts can occur without the local ground stresses being substantially elevated from their in situ levels.This paper outlines what is considered to be a credible, first-principles, mechanistic explanation for these three current development coal burst conundrums by reference to early published coal testing work examining the significance of a lack of “constraint” to coal stability and an understanding of how very specific structural geology and other geological features can logically cause this to occur in situ, albeit on a statistically very rare basis. This basic model is examined by reference to published information pertaining to the development coal-burst that occurred at the Austar Coal Mine in New South Wales, Australia, in 2014 and from the Sunnyside District in Utah, USA.The “cause and effect” model for development coal bursts presented also offers a meaningful explanation for the statistical improbability for what are nonetheless potentially highly-destructive events, being able to explain the statistical rarity being just as important to the credibility of the model as explaining the local conditions associated with burst events.The model could also form the basis for a robust, risk-based approach utilising a “hierarchy of controls” to the operational management of the development coal burst threat. Specifically, these include the use of pre-mining predictions for likely burst-prone and non-burst-prone areas, the use of the mine layout to avoid or at least minimise mining within burst-prone areas if appropriate, and finally the development of an operational Trigger Action Response Plan that reduces the likelihood of inadvertent roadway development into a burst-prone area without suitable safety controls already being in place."

Jan 1, 2019

By K. Papke

Nine western states contain significant barite deposits, but most deposits are in Nevada, which has been the principal western producer for more than three decades. Nevada produces about 85% of the total United States production, but about one-half of the barite consumed in the country is imported. Approximately 95% of the barite is used in drilling muds. Sharply decreased oil and gas drilling, starting in early 1982, severely depressed the domestic barite industry. Other problems for western barite include long distances to the areas of major drilling, high railroad-freight rates, and increased barite imports. Bedded deposits, formed by submarine exhalative processes, account for almost all western production, and reserves are large.

Jan 1, 1983

By C Taylor, E Retz

Sequential Gaussian conditional simulation of wide-spaced exploration data has been completed in order to optimise a drilling grid at Fortescue’s Eliwana deposit. The aim of this drill grid is to improve the confidence in the Inferred Mineral Resource. A mineralised domain within the Joffre Member of the Brockman Iron Formation was selected to be tested as it makes up a large proportion of the Inferred Mineral Resource and is drilled at a reasonable spacing.One hundred realisations of Fe, SiO2 and Al2O3 grades were completed in the domain. Three realisations were selected for each analyte to represent the range of equiprobable values and a further realisation was selected to represent the truth data set. These realisations were used to flag theoretical drill holes on varying spacings and patterns. The theoretical drill holes were used to estimate into block models using ordinary kriging.These estimates were analysed and the accuracy and precision of each drill spacing was assessed. It was concluded that the greatest improvement in estimation results was noted at either a 100 m × 50 m or 50 m × 50 m spacing.CITATION:Taylor, C and Retz, E, 2015. How much do we need to drill?, in Proceedings Iron Ore 2015, pp 491–500 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By F. W. Richard

This paper describing the mining practices at the Ground Hog Unit of the Asarco Mining Co., a subsidiary of the American Smelting and Refining Co., is one of a series being prepared by the United States Bureau of Mines on mining methods, practices, and costs in the various mining districts of the United Stated. The Ground Hog mine is at Vanadium in the Central mining district, Grant County, N. Mex., about 1.0 miles east of Silver City and 2 ½ miles southwest of Santa Rita. A branch line of the Atchison, Topeka & Santa Fe Railway connects Vanadium with Deming, about 45 miles southeast.

Jan 1, 1930

By M. R. Peterson

The U.S. Bureau of Mines (USBM) is investigating alternative methods to strip metal-loaded solvent extractants. Hydrolytic, precipitation, and hydrogen pressure stripping all recover metal or metal salts directly from the organic solvent extractant. Pure metals, metallic oxides, or metal salts can be formed, allowing direct production of value-added products. Aspects affecting commercial application are emphasized, including metal recovery from actual ore leach solutions, particle size control, organic modifier and diluent effects on stripping and metal recovery efficiencies, metal grade, seed addition, mixing intensity, recycling efficiency, and reactor plating. Metal separations from copper ore leach solutions and complex waste leach solutions were examined.

Jan 1, 1995

By G. L. Oldright

In the previous study that has been made by the authors on smelting in the lead blast furnace,4 the furnace examined was one that operated under conditions that have been considered as more or less normal up to the present time. That is, although the furnace had in its charge a large portion of sinter, it also handled considerable quantities of naturally oxidized direct-smelting ore. Other ingredients, such as the limestone, were also added as fairly coarse material. The charges contained only about 24 per cent of lead. Until the changes incident to modern flotation began to take effect, many lead plants doing semicustom smelting in districts where competition was keen and much of the bonanza ore was exhausted were faced with the difficulty of obtaining enough lead to get a sufficient "lead fall" in the blast furnaces to clean the slag thoroughly and to separate it from the lead. A charge containing 24 per cent of lead would have been considered a very rich one by such smelters.

Jan 1, 1931

By B. Mishra, W. A. Averill

"The application of various hydrometallurgical, pyrometallurgical and electrochemical processes in the extraction, purification and production of radioactive metals as well as the use of various materials, ego metals and alloys, ceramics, polymers, etc. in the process, construction and handling equipment in the nuclear industry has generated a large stockpile of radioactively contaminated waste material and scrap metal which can not be directly discarded, recycled or considered for long-term storage due to its volume and potential hazards, without the separation of radionuclides. This paper reviews the emerging methods that have been investigated and suggested for dealing with some of these wastes and scrap material.The separation technologies studied for the recovery of radioactive components from the pyrometallurgical and electrochemical processing wastes have been discussed in details with results from some of the recent theoretical and physical modeling work as well as the data obtained from the actual waste treatment. Specific processes shall be described in terms of its advantages and limitations. These emerging separation technologies are being considered by the US Department of Energy as alternatives for dealing with the issues of environmental management [EM] and decontamination and decommissioning [D&D].IntroductionThe high temperature carbothermic or metallothermic smelting reduction methods for metal production are associated with the generation of significant quantity of waste as slags, flue dusts, sludges, residues, effluent salts etc. Certain hydrometallurgical processes also generate lots of aqueous waste due to the inherent nature of the technique. Also, the gas-based reduction processes are not applicable to many stable metal compounds, such as alumina, titania, beryllia, lanthanide and actinide oxides, etc. due to thermodynamic considerations. All these methods cause substantial environmental hazard. There is a need to develop alternative processes which have low waste or ideally a ""zero-waste"" generation.Pyrochemical processes using molten salts provide a unique opportunity for the extraction and refining of many reactive and valuable metals either directly from the beneficiated ore (aluminum, beryllium, neodymium, plutonium, uranium, etc.) or from other process effluent that contain reactive metal compounds. The processes reduce metal compounds electrolytically (A12O 3 and BeCI2) on a carbon anode or by calciothermic reduction (Po, Nd). The by-product, in the latter case, is a calcium oxide saturated halide salt. The waste-treatment to recycle the halide has to be done as a separate step or stored as a contaminated waste. A successful separation technology can provide a new insight to the waste minimization strategy for the nuclear industry."

Jan 1, 1996

By R. L. Solmer

During 1959-61, the Bureau of Mines investigated the strain and deformation induced in rock and concrete linings around mine openings by retreat panel caving at the Climax Molybdenum mine. Two concrete-lined slusher drifts on the Phillipson level of the mine were instrumented with both electrical strain gages and extensometers. Changes in strain and deformation were recorded over an 18-month period during the undercutting and caving of the mining panel. General agreement was found between the strain and deformation measurements and the hypothesis that the vertical component of the stress field on the openings is almost completely removed by undercutting. This phenomenon is a possible explanation for the structural failures that occur in the slusher drifts during the undercutting cycle.

Jan 1, 1965

By R. S. Krarner

Fly ash, a by-product of coal burning power plants, poses a major problem for the utility industry since most fly ash must be landfilled. These quantities may represent as much as 20% of the total material going into landfills. A major problem with fly ash utilization is that although the ash consists of useable components, ash composition can vary depending on the types of coal burned and plant operating conditions. Ash is first characterized using SEM, image analysis, and chemical methods. Processing techniques were developed to separate ash into various components including cenospheres, magnetic spheres, carbon, and clean ash. These products are again evaluated for various utilizations before being used to produce valuable products such as mullite, activated carbon, fillers in plastics, and concrete.

Jan 1, 1994

By J. D. Bennett

The degree of injury and days lost from work due to an injury are examined for selected electrical sources, occurring in conjunction with falls of the injured miner or with selected machinery, that could have been eliminated by use of diesel equipment. Although the number of electrical source injuries that could have been prevented is small relative to the total number of injuries during the period examined, many lost-time injuries could have been precluded and thousands of days lost from work could have been avoided.

Jan 1, 1984

By R. R. Wells

An important activity of the Bureau of Mines is the continual search for new sources of minerals. As a part of the investigation of strategic mineral deposits in the United States, samples of mercury ores were submitted to the Ore Dressing sections of the Salt Lake City and Albany stations for metallurgical testing. This paper gives data summarizing the results obtained from laboratory beneficiation studies of mercury ore samples submitted during the period 1941 to 1947. Ores tested included three from Jackson County, Oreg., one from Valley County, Idaho, one from Storey County, Nev., and one from Sonoma County, Calif. In general, the ores from Oregon were not amenable to concentration by flotation because of intimate association of cinnabar with other minerals or because of extremely low grade. One Oregon ore was amenable to direct distillation provided lime was added to reduce corrosion of the retort.

Jan 1, 1950

By O. E. Wheeler

The use of the walking dragline as a stripping tool has increased dramatically in the past two decades. The reasons for its increased popularity and some historical background on its introduction into the mines are given in a recent paper by Learmont. (l)* The history need not be recounted here except to show the trend to longer booms which has accompanied the growth in machine size. Figure 1 shows the change in maximum operating radius on Bucyrus-Erie machines which has occurred over the years and Figure 2 shows the corresponding change in maximum boom lengths. Reference 1 also presents some of the reasons for expecting this trend to longer booms to continue. There are many design parameters affected by the increase in boom lengths; swing power, hoist and drag rope lengths, and drum capacity, to list just a few. The purpose of this paper is to discuss only the structural implications of using longer booms. As in the design of any structure, the various facets of boom design are interrelated and a process of optimization between them must be worked out either by evolution or by conscious iterative effort. The decisions we have reached about such things as material selection, structural arrangement, and applicable criteria, have not come into being overnight but represent instead many years of design experience and a fair amount of recent concentrated analytical effort. In the following pages an attempt will be made to first, state those decisions, second, explain how we arrived at that particular result; and third, describe what we expect future developments to be which might influence us to change those decisions.

Jan 1, 1976

By J Addai-Mensah, W Skinner, C Kelsey, J R. Kelly, E Baawuah

Comminution continues to be the most capital-intensive unit operation in mineral processing. The fundamental purpose of comminution is to liberate the valuable minerals so that they can be economically concentrated into saleable products. Declining ore quality characterised by lower grade and increased complexity requires significant energy consumption for comminution. Low-grade magnetite ores are typically fine-grained and require fine to ultra-fine grinding (P80 ~ 30 - 40 µm) to enhance its liberation from the typically siliceous gangue matrix. Historically, this has been achieved using multi-stage crushing and grinding technologies, which require high energy consumption with low energy efficiency. This motivated innovations in energy efficient technologies for comminution. Such technology has been developed in the IMPTEC super-fine crusher. It is an innovative, dry (with the potential to be operated wet), media-free, energy efficient crusher that can to reduce 10 mm feed particles to 19 – 30 µm with very low recycle loads. In this study, the mineralogical and physicochemical characteristics of crushed magnetite ore using the IMPTEC super-fine crusher have been investigated in comparison with those of rod milling. The super-fine crusher generated higher liberated magnetite minerals in the – 300 + 212 µm and < 45 µm size fractions compared to rod mill. Both comminution devices generated large low-grade hematite and goethite middlings. However, the rod mill produced higher locked/unliberated hematite and goethite compared to that of the super-fine crusher. Quartz mineral had the highest liberation irrespective of the comminution device used. The super-fine crusher generated higher entrapment of other minerals within the silica matrix compared to the rod mill. The breakage mechanism of the super-fine crusher which is predominantly through high compression with shear, generated improved mineral liberation in the coarse size fractions compared to the predominant abrasion and attrition breakage mechanisms of rod milling. The higher mineral liberation generated by the rod mill is potentially due to the prolonged batch milling of the ore compared to the single-pass open circuit of the super-fine crusher.CITATION:Baawuah, E, Kelsey, C, Kelly, J R, Addai-Mensah, J and Skinner, W, 2018. Mineral liberation studies of IMPTEC super-fine crusher – 130 crushed product, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 313–326 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By I Basson, J A. Miller, M Becker, F C. de Beer, L C. Bam

"Geometallurgy brings together geologists, mine planners and process engineers to extract meaningful mineralogical and textural information from an orebody, with a view to predicting its metallurgical response. Preferably, automated analytical techniques, which provide mineralogical and textural information, should process a large number of samples quickly, relatively inexpensively and reliably. Microfocus X-ray computed tomography (µXCT) is capable of producing 3D volumetric information on texture and mineralogy that satisfies some of these criteria. µXCT has been used extensively to study the porosity and internal pore structure of iron ore pellets as part of downstream processing. It has not been widely applied to earlier mineralogical and textural analysis of unprocessed ore, due to the limited ability of X-rays to penetrate high-density samples. In this contribution, we propose scanning methods to overcome this limitation, thereby facilitating a broader application of µXCT to iron ore resource management.CITATION:Bam, L C, Miller, J A, Becker, M, De Beer, F C and Basson, I, 2016. X-ray Computed Tomography – Determination of Rapid Scanning Parameters for Geometallurgical Analysis of Iron Ore, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 209–220 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Deborah A. Kramer

This Bureau of Mines report presents a cost estimate of the Bayer process, which is used for virtually all cell-grade alumina production. The report will serve as a reference point to determine the economic merits of processes that have evolved from Bureau of Mines investigations on technology for producing alumina from domestic nonbauxitic raw materials. The Bayer process involves dissolving the alumina present in bauxite in a caustic solution at high temperature and pressure. After the un- dissolved impurities are removed, the solution is seeded to produce an alumina trihydrate precipitate. This precipitate is filtered, washed, and calcined to produce the cell-grade alumina product. This cost estimate is for a plant producing 1 million tons of alumina per year. The estimated operating cost is approximately $250 per ton of alumina.

Jan 1, 1983

By David R. Cole

Before discussing some of the specific public relations issues in Colorado mining, I would like to define public relations, identify the "publics," review Colorado's population profile, and outline Colorado's mining history. Public Relations In describing public relations, a definition which is frequently quoted appeared in the PUBLIC RELATIONS NEWS, and is as follows: "The Management function which evaluates public attitudes, identifies the policies and procedures of an individual or organization with the public interest, and executes a program of action to earn public understanding and acceptance..' As you can see, this covers a "multitude of sins."

Jan 1, 1975

By F. Elgersma

A high purity electrolysis solution is essential for hydrometallurgical zinc winning processes. For this reason ferric iron containing compounds such as jarosite are precipitated as iron and impurity collector during the calcine leaching. Jarosite thus forms a chemical waste and creates environmental problems. This research contributes to the development of a wet jarosite treatment process, where less contaminated jarosite is produced which can act as an iron source. The present work studies jarosite precipitation kinetics and the uptake of zinc cations in batch and continuous experiments. The distribution coefficient for zinc in continuous experiments is constant for a wide ratio of zinc over ferric ions in the solution. Addition of NH, + ions in batch experiments accelerates the conversion rate equivalent to the driving force increment. Addition of 50,2-ions above the stoichiometric ratio increases the conversion rate less then could be expected from the increase in the estimated driving force. Zinc ions tend to retard the conversion rate. An increasing reaction temperature increases the conversion rate. Below 75 ?C the conversion rate approximates zero.

Jan 1, 1990

By G. L. Oldright

In the previous study that has been made by the authors on smelting in the lead blast furnace, the furnace examined was one that operated under conditions that have been considered as more or less normal up to the present time. That is although the furnace had in its charge a large portion of sinter, it also handled considerable quantities of naturally oxidized direct-smelting ore. Other ingredients, such as the limestone, were also added as fairly coarse material. The charges contained only about 24 per cent of lead. Until the changes incident to modern flotation began to take effect, many lead plants doing semicustom smelting in districts where competition was keen and much of the bonanza ore was exhausted were faced with the difficulty of obtaining enough lead to get a sufficient "lead fall" in the blast furnaces to clean the slag thoroughly and to separate it from the lead. A charge containing 24 per cent of lead would have been considered a very rich one by such smelters.

Jan 1, 1931

By W. N. Marchant

The Bureau of Mines performed chemical research to elaborate details of sulfur chemistry pertaining to the citrate flue gas desulfurization process in which sulfur dioxide (SO2), absorbed (as bisulfite ion) in a buffered sodium citrate solution, is reduced by hydrogen sulfide (H2S) according to the overall reaction 2H2S + HSO3 + H+ ? 3S + 3H20. The rate-limiting step in the process was shown to be the reduction by H2S of thiosulfate (S2031-) that is formed as an intermediate. Pseudo first-order kinetic measurements were made at room temperature to retard the reaction sufficiently that adequate analysis was possible. These measurements showed the rates of the following net processes to be -d [S02]/dt (pH 4.5) = (0.409±0.050)min-1 [S02]; d [S2032-]/dt (pH 4.5) = (0.199±0.017)min-1 [S02]; -d [S2032-]/dt (pH 4.0) = (0.0437±0.0265)min-1 [S2032-]~1; -dH2S/dt (pH 3.9) = (21.6±3.0) mmoles/min-atm [H2S]g1.4, where [H2S]g is the partial pressure of H2S in the gas phase, in atmospheres, and the rate describes the consumption of H2S, in millimoles per minute; d[S]/dt (pH 4.0) = (38.0±3.4)min-1 [H2S]1, where [H2S] is the concentration of H2S in solution. Hydrogen ion consumption during the slow phase of regeneration was shown to occur at (2.1±0.5) times he rate of thiosulfate consumption, which is interpreted as evidence for the following as the rate-limiting reaction: 2H2S + S2032- + 2H+ ? 4S + 3H20 A scheme consisting of five sequential general reactions is proposed to account for sulfur formation.

Jan 1, 1981