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By Albert L. Toenges

The State Division of Geology Arkansas Resources and Development Commission, and the Arkansas-Oklahoma Coal, Operators Association requested assistance from the Bureau of Mines in a study of coal-mining methods and practices in .Arkansas coal mines with the objective of reducing production costs. On October 7, 1946, a joint meeting was held by representatives of the Arkansas Resources and Development Commission, approximately 30 coal-mine Operators of the Arkansas -Oklahoma Coal Operaters Association, and representatives of the Bureau of Mines. The many problems confronting the coal industry in Arkansas, including mechanical mining in thin beds, costs, labor, and working time were discussed. Following this Meeting, a joint letter from Harold B. Foxhall, State geologist, and -P. R. Stewart, commissioner, Arkansas-Oklahoma Coal Operators Association, was addressed to Dr. R. R. Sayers; former ,Director of the Bureau of Mines, requesting that mining conditions in Arkansas be studied.

Jan 1, 1949

By LUIS EAIYLNN SALAS

IF the ordinary wet method be attempted for silver-bullion containing tin, much trouble is experienced, varying with the amount of tin present. Even with a percentage as low as 0.05, the end-point is masked by a persistent turbidity, while with amounts ranging from 0.5 per cent. upward, the determination of the exact end-point is impossible, owing to the finely divided or colloidal metastannic acid resisting all efforts to cause it to settle, or to give a clear supernatant liquid. The object of the following experiments was to seek a remedy for these difficulties, and to find the conditions whereby the Gay Lussac method might be applied directly to these bullions. Material containing tin is met with frequently in bullion from Mexico or Bolivia; and tin is carried (sometimes in large quantities) in jewelers' sweeps. 1. A bullion was prepared containing Ag, 74; Cu, 25; and Sn, 1 per cent. A weighed amount was treated by the humid assay-method as if it were an ordinary bullion free from tin. Ten cc. of HNO3 (1.21) was added, and the bottle was heated until all traces of red fumes had been expelled. Before heating, the solutions were moderately turbid; and after heating, the turbidity greatly increased. One hundred cc. of normal NaCl solution was added and the bottle was shaken vigorously at intervals during 30 min. The turbidity persisted. The bottle was allowed to stand over

Mar 1, 1912

By E. Tondu

Separation Technologies Inc.’s (STI) electrostatic separation technology is a dry, continuous process for the separation of discrete particles. This high-volume process does not require any additives nor is any additional waste produced. In December 1993, STI, in cooperation with New England Power(NEP), installed an 18-t/h (20-stph) prototype electrostatic separator at NEP’s Salem Harbor plant. The plan was to convert waste streams of type F fly ash into commercially valuable products. In July 1995, a second separator was installed at NEP’s Brayton Pointplant. Fly ash feed, ranging from 6% to 25% carbon (loss-of-ignition fly ash or LOI), is separated into <3% LOI “clean” ash and sold as a portland cement substitute in the New England concrete markets.

Jan 1, 1996

By Robert F. Chaiken

The U.S. Bureau of Mines conducted an experimental and theoretical study of coupled chemical kinetic and mass transport processes during leaching of pyrite from coal in a counterflow, "trickle-bed" column reactor. Spatial and temporal data on reactant and product concentrations were used as solutions to appropriate continuity equations, which in turn define chemical kinetic reaction rates. Data from four 180-by 30-cm column leaching experiments using coal, coal waste, and air-water and air-FeC13 lixiviants have been analyzed. The rate of leaching was found to be diffusion limited (probably by Fe3+) and not controlled by bacterial action. Rates of pyrite oxidation were found to vary with elapsed time (80 to 225 days) and followed a bell-shaped curve, sometimes with a delay before start of reaction. Maximum rates of reaction ranged from 3 to 10 (mmol/d)/L (column) for coal waste and 0.4 (mmol/d)/L (column) for coal. Reaction was 30 to SO pct complete, probably due to precipitation of product salts (e.g., jarosites), which impede transport of oxidant through the coal. An absorption-desorption model of solids leaching, which considers the role of heterogeneous porosity in solids leaching, was used to describe time-dependent leaching rates.

Jan 1, 2010

By David Melgaard

A significant emerging recycling, waste minimization problem stems from legacy waste from the nuclear weapons program and from production of power using nuclear fuel. Premium quality metals used in nuclear plants become contaminated, making them unsuitable for reuse. Consequently, decontamination studies were conducted to evaluate the decontamination capacity and partitioning effeetiveness of Electroslag Remelting (ESR). Eight laboratory melts were conducted to evaluate the efficacy of using ESR to transport radionuclides from the liquid metal phase to the liquid flux or slag phase. To determine the decontamination effectiveness, several surrogate compounds for uranium, plutonium and other fission products were added to the melts. During the melts, the melting rate was varied, typical slag additives were used, and two different slag compositions were evaluated. The resultant post-test ingots and slag were then analyzed to determine the partitioning of the surrogates. ESR generally proved very effective in removing contaminates from the metal with a few noted exceptions. -

Jan 1, 2003

By Casters B. Foster

The U.S. Department of Energy has undertaken, in a cost sharing partnership with industry and utilities, an extensive coal-oil mixture (COM) combustion program in a number of promising applications. One of these is the injection of COM through tuyeres into a blast furnace in lieu of oil. From work done previously, it has been established that COM can be burned in existing oil, fired facilities. The issues being addressed by the current DOE program are: 1) determination of best available technology to achieve environmentally acceptable operation, and 2) determination of applications for which COM can be utilized economically.

Jan 1, 1978

By R. A. Deju, R. B. Bhappu

The basic structural unit of all silicate minerals is a tetrahedron with a silicon atom at the center and four oxygen atoms at the corners. The oxygen-silicon distance is about 1.6 & and the oxygen-oxygen distance about 2.6 &. The different types of oxygen-silicon frameworks in the various silicates are based entirely on the combinations of the tetra-hedral oxygen-silicon groups through sharing of oxygen atoms. In recent years, infrared spectroscopy has permitted estimation of the ratio of the ionic character of the oxygen-silicon bond to be a few times that of the oxygen-carbon bond and the ratio of electro-negativity of the two bonds has also substantiated this finding. On this basis, it is generally accepted that the oxygen-silicon bond is the strongest one occurring in silicate minerals. As the oxygen-silicon ratio increases from quartz to the olivines, a greater percentage of the oxygen bonding power is available for bonding to cations other than silicon. Hence, with an increasing oxygen-silicon ratio, there is increasing oxygen-to-metal bonding. Upon the fracturing of a silicate mineral crystal, the oxygen-metal bond, which is almost entirely ionic in character, should break more easily than the stronger oxygen-silicon bond, resulting in a greater number of unsatisfied negative forces on the surface. If, then the mineral is immersed in a liquid containing hydrogen ions, these negative forces should tend to be neutralized by hydrogen ions from solution, resulting in a change of the pH of the solution. An increase in the degree of adsorption of hydrogen ions is to be expected as the oxygen-silicon ratio in the crystal structure increases. This study attempted to correlate the oxygen-silicon ratio for various representative silicate minerals to the adsorption of hydrogen ions. Experiments to determine the effect of surface area on this adsorption and to investigate the effect of surface iron were also conducted. It is believed that such studies of the surface properties of silicate minerals will supply pertinent information about their behavior in froth flotation systems. EXPERIMENTAL PROCEDURE Ion Exchange: Carefully selected, hand-picked samples of the minerals investigated were dry-crushed in a ceramic ball mill and sieved to obtain a minus 100 plus 200-mesh sample. The sized samples were then run through the electro-magnetic separator to remove any iron-bearing particles. A 10-g sample of each mineral was placed in 100 ml of freshly deionized water previously adjusted to a pH of 3.50 with HCl. The beaker containing the sample and the water was placed under a bell jar from which the air was displaced at once by nitrogen gas from a tank. All experiments were carried out in a nitrogen atmosphere. The sample and solution were stirred gently but continuously during the entire experiment, the stirring speed being kept about the same for all runs. Changes in pH were followed with a Beckman Zeromatic pH meter and recorded on a

Jan 1, 1967

By W. C. Risley

IN the year 1933, workings at the No. 12 colliery, New Waterford, of the Dominion Coal Company, Limited, had advanced to a point where additional ventilation would soon be required. Furthermore, development of the mine was being .made to practically double the output of coal. Consequently, authorization was given to sink a shaft to the workings. The location selected is on the west side of the mine, about one and a half miles from the slope mouth and on the Low Point shore, some 250 feet from high-water mark. The cliff at this point is 40 feet high, with the land rising on a slope of about 5 per cent to the shaft. Figure 1 shows the location with reference to the colliery workings. The strata through which the shaft was to be sunk were pretty well known from diamond-drill borings previously made, and it was believed that water would be encountered to a depth of at least 250 feet to 300 feet. It was planned, therefore, to seal-off the water by the pumping of cement grout under high pressure. This method was considered to be the most economical means of handling the water during sinking, and would also result in a permanently dry shaft. Figure 2 shows a cross-section of the strata. The permanent shaft hoist and fan were to be electrically driven, which would necessitate the construction of a transmission line between the colliery and the shaft; therefore, it was arranged that the sinking equipment would have electric drive. As all equipment, materials used in construction, and supplies were to be hauled by truck, a roadway 1,800 feet long was required from the main highway to the site, and as heavy loads would be hauled during the fall, winter, and succeeding spring, this road was ballasted with 18 inches of clinkered material obtained from a burned culm bank one and a half miles distant. Actual field work was begun by the Company&apos;s own forces early in October. Work preparatory to sinking-in addition to the roadway and trans-mission line-included the construction of the reinforced-concrete shaft collar and fan drift connection; the permanent timber headframe (which was to be used also as the sinking headframe); the permanent reinforced-concrete building to house the shaft hoist and fan drive; and the erection of temporary buildings and installation of all equipment for sinking and lining the shaft and for cementation.

Jan 1, 1936

By C. M. Lesher, R. R. Keays

"The komatnte-associated Fe-Ni-Cu sulphide mineralization at Kanihalda, Western Australia, is generally believed to be magmatic in origin, but a number of postmagmatic processes significantly modified the original distribution, structure, texture, mineralogy and chemistry of the ores. Two important types of mobilized magmatic sulphides are interpillow/interbreccia sulphides and hydrothermal vein-type sulphides. Interpillow and interbreccia sulphides occur interstitial to pillowed or volcaniclastic footwall metabasalts beneath or adjacent to the stratiform contact ore horizons. They are mineralogically and compositionally similar to massive ores (and are similarly depleted in PGE relative to the compositions of bulk samples of mined ores), but normally do not contain the distinctive chalco-phile ferrochromites characteristic of contact ores. They are interpreted as magmatic sulphides that have been mobilized from the overlying or adjacent massive sulphide layer during peak tectono-nietamorphism.Hydrothermal sulphide-quartz + albite veins also occur in the footwall metabasalt and contain unannealed deformation fabrics indicative of emplacement during retrograde metamorphism. The high Ni and Pd contents of these sulphides (7-13% Ni, up to 70 ppm Pd) indicate that the metals have been derived from the spatially associated komatiites and/or contact ores, consistent with the Pd depletion previously inferred for massive ores. Very low Ir contents and high Pd/Ir ratios of the vein-type sulphides confirm an aqueous transportation-deposition mechanism; hydrothermal transfer of PGE results in strong decoupling of Pd from Ir.There appears to be a complete continuum of sulphide mobilization at Kambalda ranging from whole-scale phy sical dislocation (fault offset ores) and selective mobilization (stringer sulphides) through nietamorphie replacement (interpillow/interbrec- cia sulphides) to jiydrothermal dissolution and redeposition (vein-type sulphides)."

Jan 1, 1984

By W. C. Meyer

The concept of using powdered coal-in-oil-mixtures (COM) as a composite fuel to conserve oil resources and relieve import supply problems is being vigorously promoted by the Department of Energy via the sponsoring of various demonstration units (1). The idea of COM as a useful alternative fuel has been explored on and off for over 100 years (2). The approach must be capable of grinding, mixing, storing, and combusting COM with presumably only minor equipment changes on oil-fired boilers. DOE estimates that 56 000 m3 of oil (350 000 barrels) could be spared daily if a 50-50 COM was used to generate electricity. Of course, the ability of COM suppliers to prepare and deliver a stable suspension of COM at reasonable economic costs must be achieved if the concept is to be successful. This report reviews the various methods used to attain stable coal-oil mixtures. Various physical-chemical principles associated with each method of stabilization are also discussed.

Jan 1, 1981

By Sarah Wilson, John Kaplin

Plans are underway to extend commuter rail service underground into downtown San Francisco. The Salesforce Transit Center (STC) was completed in 2018 and will serve as a new transit hub, including a commuter rail station after two future connecting tunnel segments are completed. The northern segment, known as the Caltrain Downtown Extension (DTX), which will extend the rail line from its current terminus at 4th and King Streets to the STC, is currently in Preliminary Engineering. The southern segment, the subject of this paper, is a 1.6-mile tunnel known as the Pennsylvania Avenue Extension (PAX), which is currently in the pre-environmental planning stage, with alternative alignments under evaluation including single bore versus twin bore options. This paper discusses project challenges, including highly variable tunneling conditions in soil and rock, a congested urban project site with limited space for construction staging, alignment crossings of large existing buried infrastructure, and complicated interfaces with future and existing rail operations.

Dec 1, 2022

By C. G. McLachlan

Abstract This paper deals with the application of the cyanide process to recover gold from a pyrite concentrate produced by means of differential flotation. This concentrate before cyanidation contains from 0.09 oz. to 0.14 oz. gold per ton, of which only about 60 per cent is recoverable. The rest is so fine that it remains interlocked in the pyrite and therefore is not acted on by the cyanide. The concentrate also contains about 15 per cent pyrrhotite and 0.4 per cent chalcopyrite, both of which are cyanicides. The cyanicidal effect of the pyrrhotite is inhibited by preacracing the pulp with lime, and maintaining a high lime alkalinity during cyanidation. The effect of the chalcopyrice is reduced as far as possible by removing those particles which are free by means of a further flotation step immediately prior to cyanidation. This involves the flotation of some very fine material. After nullifying as far as possible these two cyanicides, the concentrate is cyanided directly, i.e., without being roasted. This leaves the pyrite available for subsequent sale as a source of sulphur dioxide and sulphuric acid, and the entire residue of the cyamde plant, amounting to about 500 tons per day, 1s now being disposed of in this way. Prior to deciding on direct cyanidation, a number of laboratory roasting tests were made. These showed chat, 1f proper control were exercised, a better recovery of gold could be effected from the roasted product than by the direct method of treatment. The tests also showed that the capital cost o the plant would be much higher than that needed for the procedure adopted. The possibility of subsequently selling the pyrite for its sulphur content would also have been eliminated. Introduction A previous paper has described in considerable detail the application of the flotation process to improve gold recovery from Noranda&apos;s milling ore, and in so doing has covered the production of an auriferous pyrite concentrate. The present paper deals with the recovery of gold by cyanidation from that concentrate. This gold, though intimately associated with the pyrite, can, for metallurgical purposes, be considered as all occuring in the native state.

Jan 1, 1946

By M. N. Nabighian

Utilization of x-ray diffraction data for mineral identification has been well documented and accepted as an analytical tool in industrial and research organizations. However, the search for new methods to minimize errors affecting measured reflection intensities is being carried out by all concerned. Recent application of computer capability has greatly reduced the time required in handling data for mineral analysis and has increased the capability of accepting more data for greater precision. The purpose of this communication is (1) to describe the concept of cross-power in XRD analysis, and (2) to show that direct comparison analysis for multiphase systems has improved analytical accuracy when all available x-ray diffraction data are used in conjunction with high speed data processing by computer.

Jan 1, 1972

By Carroll W. DeKock

Thermodynamic data for selected metal sulfates were critically evaluated and compiled as part of the Bureau of Mines program to provide a scientific base for use in developing new technology and predicting the feasibility of new processes. Values for Cp°, S°, H° - H°298, -(G° - H°298)/T, ?Hf°, ?Gf°, and log Kf as a function of temperature are given in tabular form. Thermodynamic data were compiled for VOSO4, Cr2(SO4)3, MnSO4, FeSO4, Fe2(SO4)3, CoSO4, NiSO4, Cu2SO4, CuSO4, CuO-CuSO4, ZnSO4, and ZnO-2ZnSO4, together with their stable hydrates.

Jan 1, 1982

By Robert H. Richards

(Read at the Amenia Meeting, October, 1877.) DURING the summer of 1870, I had an opportunity to visit the laboratory of the late David Forbes, Esq., in London, and was much interested in a labor-saving device which lie had attached to his agate mortar. The mortar was placed in the centre of a small table, and about ten inches to the right of the mortar, a post, perhaps two

Jan 1, 1878

By William A. Riggs

Salt, a non-metallic mineral whose use dates back to earliest history of mankind, and whose uses cover the widest range for any mineral raw material, is generally of widespread occurrence in commercially recoverable quantities in the oceans, in certain sedimentary rocks, in certain lakes, and in certain underground waters. Passing over geological detail, it may be said that, generally, all of the salt in the world has, at least once in geological history, been in solution in the oceans. The total salt content of today&apos;s oceans, said to equal 4.5 million cubic miles of rock salt, dwarfs the tremendous volume of salt in the sedimentary rocks. In 1958, United States production of salt was about 22 million net tons and world production about 82 million. About 3 percent of United States production is table salt, with chemical, municipal, industrial and agricultural uses taking the remainder. Mississippi River. Figure 1 has been expanded sufficiently to show also those salt occurrences and producing points which might economically ship salt into these states. Although widespread in occurrence, salt deposits and possible production areas generally show very sharp local boundaries. Salt-for non-table use is susceptible to ?place value?, a common problem in low valued raw materials, where transportation costs often exceed the value of the material f.o.b. the production point. Generally only large capacity mechanized salt producing operations can compete in United States markets, as contrasted to the many small local salt evaporators in less industrialized Mexico.

Jan 1, 1962

By G. T. G. Emere

With the assistance and encouragement of Mr B.C. Alberts, the Institute&apos;s immediate Past President and Iscor&apos;s Senior General Manager: Mining, the Committee of the Johannesburg Branch recently organized a two day excursion for members to the northern Transvaal. The itinerary included visits to the Grootegeluk colliery, the Matimba power-generation utility, and the Thabazimbi iron-ore mine.

Jan 1, 1989

By Alan A. Campoli

The US Bureau of Mines (USBM) conducted research to develop improved guidelines for selecting the type and pattern of roof support in different geologic environments. The goal is to minimize the over and under design of mine roof support, resulting in more productive and safer mines. To obtain the necessary data on roof behavior and support performance, USBM conducted several field studies. Each study covers roof geology, stress regime, ground reaction, support interaction and mining environment. A consistent experimental design is being used. This includes measurements of roof bolt loads and roof movements. So far, 10 studies have been conducted in several geologic settings.

Jan 1, 1996

By D. Zim

Mining activity in South America is a growing enterprise. One of difficulties found in many areas of the South American continent, especially in north Chile and south Peru, is the shortage of water supply. In order to overcome this difficulty some mining companies proposed to transport the water from Pacific Ocean up to the mountains. This can be accomplished by the use of stainless steel pipelines, but this is a cost prohibitive solution and is also subject to severe pitting corrosion in a saline environment. The use of mild steel may be a lower cost solution than stainless steel as the material of construction for pipelines but it is subject to corrosion anyway. The corrosion in this case can be internal or external corrosion although cathodic protection as well preventive maintenance usually is enough to mitigate external corrosion without the need to shut down the pipeline. The same is not true about the prevention of internal corrosion. It is not practical, sometimes not even possible, shutdown a pipeline to carry out an inspection and fix sections where potential failures are detected. It is possible avoid corrosion caused by sea water within the mild steel pipelines by applying a proper chemical program designed to virtually eliminate dissolved oxygen in the water commonly called deaeration.1 This type of treatment obviously involves additional capital investment since it requires the construction of one deaerator with the first pumping station and additional equipment at each point where the water can come into contact with oxygen. Deaerators will increase operational costs and subsequent injection of chemicals will be required in the case of multiple degasification facilities thus increasing the consumption of chemicals. grams based on oxygen scavengers, the objective of the present study is to develop a new water treatment capable of preventing mild steel corrosion in aerated sea water. The new treatment must be able to prevent both generalized and localized (pitting) corrosion and overcome the necessity to construct and operate deaerators.

Feb 23, 2014

By E de Necker, F D. I Hodg, L-M Cruywagen

The acid mine drainage (AMD) situation at three opencast collieries in the Witbank Coalfield, South Africa, was evaluated from different perspectives. Twenty-seven test pits were dug into the spoils of these collieries to characterise the in situ conditions of spoils of varying age. Detailed static testing was done on surrounding drill holes and additional samples were taken from the test pits. Selected samples were tested using different techniques, namely ABA, mineralogy and kinetic tests. Groundwater monitoring boreholes from the areas surrounding these spoils were also used for characterisation. The ABA results compared favourably with the in situ determinations; acidic test pits proved to be potentially acid-generating from ABA, even when the samples had neutral paste pH. Kinetic test results showed these samples to yield low pH leachate over the test period. In several of these results, the theoretical depletion of neutralising potential and the onset of acidity were well matched. NAG pH-values and final observed water chemistry corresponded for the cells predicted by ABA to acidify, but compared poorly in cells that did not acidify. Results from the non-acidic spoils were consistent with the in situ observations. Alternative kinetic test methodologies were also employed. Duplicate samples were tested in humidity cells and in aerated trays that were manually wetted on a regular basis. Results from these tests showed an excellent correlation. Detailed mineralogical determinations using XRD and XRF were used for comparison to the ABA and, in some cases, humidity cell results. These comparisons show that the ABA results are consistent with the results expected from the mineralogy. The conclusion from these assessments is that ABA, in most cases, provides information that can be correlated to the field, mineralogy and to humidity cells. The use of multiple techniques leads to a higher degree of confidence in the use of the data.

Jan 1, 2003