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By Wayne Hilgedick

Peabody Coal Company is the nation's largest producer of coal and is headquartered in St. Louis, Missouri. In 1978 Peabody divisionalized its operations to establish more responsive and effective mine management. Peabody Coal Company's Arizona Division operates two large surface mines, the Black Mesa and Kayenta Mines. Both are located in northeastern Arizona, approximately 30 miles from Kayenta, Arizona, on the Navajo and Hopi Indian Reservations. The Black Mesa Mine produces 4 to 5 million tons of coal per year and the Kayenta Mine produces 7 to 8 million tons per year. Coal from the Black Mesa Mine is transported 274 miles by coal slurry pipeline to the Mohave Generating Plant located on the Nevada/Arizona border at Bullhead City, Arizona. This plant is jointly owned by Southern California Edison, the Los Angeles Department of Water and Power, Nevada Power Company and Salt River Project Agriculture Improvement and Power District.

Jan 1, 1983

My closest personal connection with the problems of rehabilitation comes from two years spent on a project at Weipa. At the beginning I am fairly certain that the engineers did not understand the mental processes of the ecologist they were dealing with. I am absolutely certain that the ecologist did not understand the minds of the engineers. This form of the two cultures problem is the root of some of the matters that lie behind this lecture. It is possible to establish a stabilising cover of vegetation on virtually any land surface, short of a cliff. While the biologist knows this he also knows that the physical and chemical nature of a given acre of land combines with climate to define quite sharply just what plants can be grown there. In the case of land after mining the range of plants may be quite limited. The engineer, and his masters in the accounting section, seem (in my experience) to expect that rehabilitation can be carried on with equal speed and facility in any location. This belief commonly leads to a situation where rehabilitation is not considered until mining is well under way. True, the mine must be proved as an assured profit- earner before money can be justified for the non-productive (to the miner) expense of rehabilitation. But when the miner finally starts rehabilitation he does not always get a convincing and speedy result. Furthermore, the failure may not be easy to overcome. This is even more likely to be the sequence of events if the miner wants, or is obliged, to specify the exact type of vegetation to be produced, e. g. commercial forest, pasture,' or the original native vegetation.

Jan 1, 1971

By Eric E. Cather

Approximately 270,000 cu yd (20[0],000 cu m) of inferred subeconomic auriferous gravel resources were estimated in three Tertiary deposits in the Polk Springs study area (fig. 1 and table 1). These resources are exposed between tuff-breccia and lava flows of the Pliocene Tuscan Formation and Paleozoic or Mesozoic metamorphic rocks which suggests that although no deposits were identified in the other RARE II areas, they may be concealed beneath the Tuscan Formation. Difficulty in choosing drilling targets will make the likelihood of resource discoveries small. The development and production of these deposits would also be prohibitive under current economic conditions due to the thick covering of volcanic rocks. Recent stream gravels of Deer Creek in the Polk Springs study area contain enough gold to attract gold hobbyists; however, the stream gravels do not have sufficient volume to be considered a resource. Potential exists for additional auriferous gravels near the Occidental Mine in the Polk Springs RARE II area.

Jan 1, 1983

By I. Ince, S. Kahraman

Preparation of suitable core specimens for physico-mechanical testing s not always possible, particularly for soft and clay-bearing rocks. Although several indirect test methods have been proposed to predict the properties of rocks, specimen preparation from soft rocks for some indirect tests is still difficult. For such cases, the needle penetration test has been developed. In this paper we present a study on the predictability of the physico-mechanical properties of pyroclastic rocks from the needle penetration index (NPI). The NPI, uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density, and porosity tests were performed in the laboratory on specimens from ten different locations in Turkey. Correlations were established between the NPI values and the physico-mechanical properties. Strong correlations were observed between NPI and both UCS and BTS. General correlations were found between NPI and both density and porosity.

Sep 6, 2023

By R. L. Rough

The Bureau of Mines analyzed rotary-coring-operations data to compare mud and air as coring mediums, and to compare core recoveries, penetration rates, and cost data for the respective mediums as part of an investigation of the susceptibility to secondary-recovery techniques of petroleum reservoirs in Ohio, Pennsylvania, and West Virginia. This report describes the rotary-diamond coring equipment and operations employed while coring 20 wells--10 cored using mud, and 10 cored using air. Data relevant to the draw works, rotary-table power, drill pipe, drill collars, core barrel, core head, mud pumps, or air compressors are tabulated. Average bit weight and rotary speed, core recovery, and penetration rates are listed for each formation cored. In general, core recoveries were better from the mud-cored wells, whereas penetration rates were faster for the air-cored wells. Coring costs were about the same for single-formation wells cored with either mud or air; however, costs increased considerably when multiple-formation wells were cored with air.

Jan 1, 1969

By Randy Wheeler

One of the more difficult topics to address concerns the effects of vibration on historic structures. Not only blast induced vibration, but also vibration from other transient and semi-continuous sources like, traffic, human activity, and environment forces. A common question might be, “What level of blast-re l a ted PPV is considered safe?” A review of some of the papers available from the ISEE Explosives Reference Database on CD ROM shows that 0.50 inch per second was often used. It was not clear on what basis this value was selected except that it represents the low frequency limit for plaster developed by the United States Bureau of Mines in RI 8507. In another case, a limit of 0.20 inch per second was mentioned, apparently simply because it was ten times less than 2.00 inches per second.

Jan 1, 2004

By A. M. Kivari

Operations at the cement plant of the Permanente Corporation, in the hills about 45 miles south of San Francisco and 12 miles west of San Jose, are interesting to the members because of the adoption of modern hydrometallurgical methods for handling and beneficiating raw materials. Closed-circuit grinding, classification, hy-droseparation, flotation, agitation, and thickening are familiar terms at this cement plant. These methods make it possible to process refractory limestone into suitable materials for the mallufacture of modern cements. Construction of the plant, having originally a design capacity of 7000 bbl. of cement per day, was started in June 1939, and the first clinker was ground on the following Christmas Day. At present the capacity is about 12,000 bbl. of finished cement per 24 hr., most of the production being low-heat cement. † About 3I30 tons of limestone, 620 tons of clay and I00 tons of gypsum are required daily for this output. Occasionally iron oxide is added to the clay to obtain the desired composition. This, together with the gypsum, is purchased from outside sources. up to the present time, the ccrporation has produced low-heat, normal, moderate-heat, moderate-sulphate-resisting, high-early-strength, oil-well, modihed-oil-well, and plastic cements. Most of the present production is for Shasta Dam, near Red- ding, Calif., the total demand being 5,800,000 bbl. of cement. Following are some of the cement require ments of the Shasta Dam specifications: Per Cent Chemical composition: Loss in ignition.......... 2.25 Insoluble residue......... 0.75 SO3.................... 2.25 MgO................... 5.'' Uncombined lime in clinker (CaO)......... I.25 Percentage of iron oxide to alumina ratio....... I.5 Compound composition: Tricalcium silicate (3CaO.SiO2)........... Not more than 35 Dicalcium silicate (zCaO.SiO2)........... Not less than 40 and not more than 65 Tricalcium aluminate (3CaO.Al2O3).......... Not more than 7 Tetracalcium aluminofcr- rite (4CaO.Al²O³.Fe²O³) Not more than 20 Fineness: The average specific surface in the bin sampled shall be not less than 1800 sq. cm. per gram and no individual sample less than 1600 sq. centimeters. Compressive strength: The average compressive strength in pounds per square inch of three mortar cubes composed of one part cement and 2.75 parts fine testing sand, by weight, shall be equal to or greater than the following:

Jan 1, 1942

By A. M. Kivari

Operations at the cement plant of the Permanente Corporation, in the hills about 45 miles south of San Francisco and 12 miles west of San Jose, are interesting to the members because of the adoption of modern hydrometallurgical methods for handling and beneficiating raw materials. Closed-circuit grinding, classification, hy-droseparation, flotation, agitation, and thickening are familiar terms at this cement plant. These methods make it possible to process refractory limestone into suitable materials for the mallufacture of modern cements. Construction of the plant, having originally a design capacity of 7000 bbl. of cement per day, was started in June 1939, and the first clinker was ground on the following Christmas Day. At present the capacity is about 12,000 bbl. of finished cement per 24 hr., most of the production being low-heat cement. † About 3I30 tons of limestone, 620 tons of clay and I00 tons of gypsum are required daily for this output. Occasionally iron oxide is added to the clay to obtain the desired composition. This, together with the gypsum, is purchased from outside sources. up to the present time, the ccrporation has produced low-heat, normal, moderate-heat, moderate-sulphate-resisting, high-early-strength, oil-well, modihed-oil-well, and plastic cements. Most of the present production is for Shasta Dam, near Red- ding, Calif., the total demand being 5,800,000 bbl. of cement. Following are some of the cement require ments of the Shasta Dam specifications: Per Cent Chemical composition: Loss in ignition.......... 2.25 Insoluble residue......... 0.75 SO3.................... 2.25 MgO................... 5.'' Uncombined lime in clinker (CaO)......... I.25 Percentage of iron oxide to alumina ratio....... I.5 Compound composition: Tricalcium silicate (3CaO.SiO2)........... Not more than 35 Dicalcium silicate (zCaO.SiO2)........... Not less than 40 and not more than 65 Tricalcium aluminate (3CaO.Al2O3).......... Not more than 7 Tetracalcium aluminofcr- rite (4CaO.Al²O³.Fe²O³) Not more than 20 Fineness: The average specific surface in the bin sampled shall be not less than 1800 sq. cm. per gram and no individual sample less than 1600 sq. centimeters. Compressive strength: The average compressive strength in pounds per square inch of three mortar cubes composed of one part cement and 2.75 parts fine testing sand, by weight, shall be equal to or greater than the following:

Jan 1, 1942

By A. K. Bhasin

The movement of solid particles in a liquid represents an area of interest in many fields of science and technology. Knowledge of the behavior and characteristics of solid-liquid suspensions is of great importance to many areas of mineral processing. In order to characterize a solid-liquid system, the following factors must usually be considered: a) density of the liquid b) rheological properties of the liquid c) density of the solid particle d) size and shape of the solid particle e) volume fraction of solid particles f) relative motion of solid particles and liquid phase Other variables such as the effect of the containing vessel walls, Brownian movement, inter-particle friction, fluid slip and electrostatic effects, are important in special circumstances. Thus it is evident that a complete theoretical treatment is not possible covering all situations. Studies of the kinematic behavior of solid particles in a liquid have been approached by two methods: 1) Assessing the movement of a single particle and extrapolating to a multi-particle system; 2) Modifying the continuum mechanics of single-phase liquids in such a way as to account for the presence of solid particles. The first approach in general utilizes the method of particle mechanics. Extension to a multi-particle system gives rise to very complicated mathematical computation. The creeping motion equations do, however, furnish a practical, useful basis for achieving a uniform treatment and a better understanding of the phenomena. This approach is useful in the study of sedimentation and hindered settling processes.

Jan 1, 1971

By B. D. Harden

FOR over fifty years the Spanish mine, 21 miles northeast of Nevada City, in Nevada County, California, has been one of the Bradley properties. Between 1883 and 1889 it was operated by the late Frederick W. Bradley and P. R. Bradley. The ore averaged only about $1 a ton at that time but the mine was credited with a production of about $900,000 in that period. The property was then closed down until 1922, when the Bradley interests reopened it and continued development for the next nine years, when a 50-ton mill was built. This began operation in April, 1931. This was a selective flotation plant, with the tailing treated on Wilfley tables, and operated on ore from the No. 4 and No. 16 tunnel stopes. This ran from $3 to $6 in gold, 2 to 3 oz. of silver, copper 0.6 per cent, lead 1.5,

Jan 1, 1935

By M. Mokgohloa, T. R. Stacey

Boring of tunnels and shafts in hard rock under high stress conditions is becoming more common as mines and tunnels are developed at greater depths. Under the high stress conditions, fracturing of the often-brittle rock occurs in the walls, backs, and ahead of advancing faces of excavations. Fracturing can have a significant impact on boring activities: sidewall spalling, which affects machine gripper capacity, and fractures can also develop in the rock ahead of the face, leading to blocky rock conditions, which may have a significant effect on machine excavation. Fracturing may develop dynamically, leading to rock bursts manifesting in the form of strain bursts, which can be hazardous and destructive. In brittle rock, fracturing is commonly extensional in nature. The focus of this paper is on fracturing in the face of the excavation. Examples of such fracturing behaviour are described briefly in the paper. Numerical analyses were carried out to predict the initiation of extension fractures and their orientations ahead of excavation surfaces, and the resulting formation of rock slabs/plates, and the stability of these plates. The results should be beneficial for the evaluation of the conditions prior to, and during boring operations.

Nov 27, 2024

By Albert J. Forney

Extensive studies have been made of the various effluents found in the Synthane coal-to-gas process. Analyses have been made of the waters, gases, and trace elements present in some of the streams. Results of analyses show the water effluents are the area where extensive research is needed.

Jan 1, 1974

By Terkel Rosenqvist

Few subjects in iron metallurgy and steelmaking have caused so much discussion and have resulted in so many divergent and partly contradictory statements as the theory of the distribution of sulphur between molten iron and slag. An interesting survey of the different points of view is given by Grant and Chipman.1 Grant and Chipman themselves conclude in their paper that, at least in the open hearth and electric steel furnaces, the governing reaction is a simple distribution like: FeS steel ? FeS alas [Ia] and MnS steel ? MnS alas [Ib] They conclude that no significant reaction takes place according to the more classical scheme: FeS steel + CaO slag ? FeOslag + CaS slag [2a] This is the reaction which is regarded by most investigators as the primary sulphur reaction in the blast furnaces, where it is accompanied by the reaction with carbon: FeO slag + C ? Fe + CO [2b] The writer suggests an alternative to the reactions mentioned above. It is the opinion of the writer that the a priori assumption of defined molecular compounds being present in molten steel as well as in molten slag, has retarded rather than promoted a solution of the sulphur problem. As for the constituents of molten steel, it is taking too much for granted to mention the presence of FeS and MnS. If this infers that the melt contains diatomic molecules, the statement must be made that at least such molecules do not exist in the solid state at room temperature. Solid FeS crystallizes in the nickel-arsenide structure, and MnS (high temperature form) in the sodium-chloride structure. In these structures the sulphur is surrounded by six metal neighbors, and no molecular groups can be isolated. When sulphur is dissolved in molten steel, it is expected to maintain the same coordination number as in the solid state. We know that sulphur in steel has a certain chemical potential and a chemical activity which can be expressed by the reaction: S steel + H2 ? H2S where the activity A. is proportional to the ratio PH2S/Ph2. We know also that this activity is influenced by the presence of other constituents. For instance, there is reason to assume that carbon and silicon increase the sulphur activity and manganese decreases it. However, the exact relationship here is scarcely known, and further investigations are needed. Concerning the molten slags, if anything should be assumed a priori it would be that they are composed of ionic rather than molecular parts. There are indications of this in that solid silicates form ionic structures, and molten slags show high electric conductivity and can be electrolyzed.2 It has been claimed by Taylor and Chipman3 that their activity investigations

Jan 1, 1949

By Terkel Rosenqvist

Few subjects in iron metallurgy and steelmaking have caused so much discussion and have resulted in so many divergent and partly contradictory statements as the theory of the distribution of sulphur between molten iron and slag. An interesting survey of the different points of view is given by Grant and Chipman.1 Grant and Chipman themselves conclude in their paper that, at least in the open hearth and electric steel furnaces, the governing reaction is a simple distribution like: FeS steel ? FeS alas [Ia] and MnS steel ? MnS alas [Ib] They conclude that no significant reaction takes place according to the more classical scheme: FeS steel + CaO slag ? FeOslag + CaS slag [2a] This is the reaction which is regarded by most investigators as the primary sulphur reaction in the blast furnaces, where it is accompanied by the reaction with carbon: FeO slag + C ? Fe + CO [2b] The writer suggests an alternative to the reactions mentioned above. It is the opinion of the writer that the a priori assumption of defined molecular compounds being present in molten steel as well as in molten slag, has retarded rather than promoted a solution of the sulphur problem. As for the constituents of molten steel, it is taking too much for granted to mention the presence of FeS and MnS. If this infers that the melt contains diatomic molecules, the statement must be made that at least such molecules do not exist in the solid state at room temperature. Solid FeS crystallizes in the nickel-arsenide structure, and MnS (high temperature form) in the sodium-chloride structure. In these structures the sulphur is surrounded by six metal neighbors, and no molecular groups can be isolated. When sulphur is dissolved in molten steel, it is expected to maintain the same coordination number as in the solid state. We know that sulphur in steel has a certain chemical potential and a chemical activity which can be expressed by the reaction: S steel + H2 ? H2S where the activity A. is proportional to the ratio PH2S/Ph2. We know also that this activity is influenced by the presence of other constituents. For instance, there is reason to assume that carbon and silicon increase the sulphur activity and manganese decreases it. However, the exact relationship here is scarcely known, and further investigations are needed. Concerning the molten slags, if anything should be assumed a priori it would be that they are composed of ionic rather than molecular parts. There are indications of this in that solid silicates form ionic structures, and molten slags show high electric conductivity and can be electrolyzed.2 It has been claimed by Taylor and Chipman3 that their activity investigations

Jan 1, 1949

By Mikhail P. Nesterov

The paper presents the results of the research that can forecast the development of subsidences and deformations of the earth surface with time in the permanent marginal areas of the movement troughs arising when mining sylvinite beds in the Upper Kama deposit of potash ores where the rock formation support is made by means of interchamber (rib) pillars of various yieldability.

Jan 1, 1997

Some crystal chemical properties of several apatites from Brazilian deposits and occurrences were determined; the samples had different origins (igneous, metamorphic and sedimentary). The aim was to establish relationships to their froth flotabilities behaviour. Detailed X-ray diffraction studies were carried out, to determine precisely the unit cell parameters and the degrees of crystallinity of the apatite samples. A thorough chemical analysis of these minerals was also conducted. Microflotation studies were carried out, using sodium oleate and dodecylammonium chloride as collectors. The crystallinity levels were determined for all samples studied, with the establishment of a crystallinity index, which varied from 10.0 to 4.5, on a normalised scale. A marked dependence was observed between this crystallinity sequence and flotability; for both collectors, flotability dropped drastically for crystallinity indices lower than 8.0. Also, the low crystallinity apatites showed a decrease in floatability, for longer conditioning times.

Jan 1, 1993

By Gerasimenko MP

The authors consider the features and advantages of a new promising trend in mineral processing - column flotation. Design aerohydrodynamic and process characteristics of pilot-scale columns are studied. Optimum process parameters for various ores and operations are studied. Flow patterns in cells of various cross-sections are investigated and the relationship between Peclet criterion and specific capacity of cell is determined. On this basis options were developed for optimisation of hydrodynamic characteristics of large capacity cells, including longitudinal sectionalising of the collection zone. It is shown that advantages of high column cells (10 - 13 m) produced in the West can be implemented in a sectionalised machine of smaller height (5 - 6 m). Investigations on the influence of slurry and air bubbles flow patterns indicated that to increase flotation rate of particles of various flotabilities it is expedient to combine co- and counter-current flows of phases in a single column. The proposed designs allow tailings to repeatedly return tailings to the collection zone and alternate co- and counter-current slurry and air flows. For the first time columns with alternating slurry flows (combination of co- and counter-current flows) are developed and commercialised. Unique multi-sectional cells having a number of essential advantages compared to monocells are developed. Design features of the cell allow: implementation of different flotation process flowsheets in a single unit, improved beneficiation process results, reduced specific power requirement, and elimination of sludging of the aerator and cell bottom part. Operational problems restricting introduction of column cells are connected with the aeration unit. The new cells are supplied with pneumohydraulic and stepped airlift spargers, allowing control of bubble size distribution with a service life of not less than three years. Successful operation of the new generation of columns with cell volumes of 15, 25, 40, and 80 cu m and the height of 5 - 6 m in copper, molybdenum, antimony, tungsten and nickel ores and coal slurry processing at different plants in this country illustrated their considerable process and operational advantages and verified the proposed options and relationships. A simulation technique of the flotation process and models for the solution of various problems are developed. A modular model of column flotation is constructed taking into account the kinetic relationship of the process and the hydrodynamic regime in the cell. Based on this, a technique of calculating the column parameters based on laboratory tests is developed (scaling-up), and applied for calculating the design of commercial-scale columns is developed.

Jan 1, 1993

By Wolfgang Roth

In 1990, a residential area above the North Outfall Sewer (NOS) tunnel constructed in 1924, experienced subsidence. After sewage was diverted into the North Outfall Replacement Sewer (NORS), soil probing from within the tunnel was conducted, soil-improvement options were developed, and a preferred grouting scheme was analyzed by numerical modeling to evaluate the stability of the 80-year+ old tunnel liner under grouting-induced loading conditions. This paper discusses the initial field investigation and the development and analysis of a grouting scheme originally intended to be implemented before relining of the tunnel. The scheme was later modified, and the new liner was installed before the final probing and grouting work was done.

Jan 1, 2008

By Zdenek D. Hora

British Columbia is an important producer of a variety of industrial minerals for both domestic and export markets. Some commodities such as limestone, dolomite, gypsum, calcium carbonate, silica, barite and magnetite are raw materials for well-established industries located in British Columbia, Alberta and northwestern USA. Others, like magnesite, sulphur, jade, asbestos, dimension stone and clay products, are mainly exported in processed form to overseas customers. Companies are developing markets for relatively new mineral products, including pumice, volcanic cinder and zeolites. A number of attractive geological targets have been identified by industry while research by government geologists has outlined the potential for refractory minerals, gemstones, garnet, nepheline syenite, carbonatites, residual kaolin, igneous apatite and peat.

Jan 1, 2001

By Yuanbo Zhang, Guanghui Li, Zhenyu Fan, Tao Jiang, Xiaohui Fan

"Iron ore sintering process is the main source of SO2 generated in the steel industry, of which the discharge amount of SO2 emission accounts for about 60% of the total. Aiming at the features of sintering flue gases and existing problems during the flue gas desulphurization, a technical route of flue gas circulation sintering (FGCS) for iron ores has been put forward. Under the simulated experimental conditions, effects of FGCS process on the main output and quality indexes and SO2 emission rule are researched using simulating flue gases. Compared the novel FGCS with conventional sintering process, SO2 in the final sintering flue gas is obviously enriched and the total exhaust gases can be reduced evidently. The decreasing of oxygen content in circulating gases has bad effect on the sintering indexes. Increasing the oxygen potential is beneficial to obtain high quality sinters. This investigation shows that the FGCS process is promising.IntroductionSteel is a kind of essential material for modern society, but steel-making process is characterized by high energy-consumption and emission as well as heavy environmental pollution. Chinese steel industry has developed rapidly in the last decade, and the environmental problem caused by ironmaking and steelmaking have also aroused the greatest concern, especially the atmospheric pollution caused by SO2, CO2, etc. Iron ore sintering process is the main source of SO2 generated in the steel industry, of which the discharge amount of SO2 emission accounts for about 60 % of the total. The development of the desulfurization process for sintering flue gases to reduce SO2 emission in sintering process is not only the requirements of sustainable development but also the most important environmental tasks for steel industry [1-5]."

Jan 1, 2011