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By W. M. Houston

Pebble phosphate deposits of Florida have been established from south of Hardee County to north of the Georgia state line or a distance of over 200 miles and mining has been carried out in an ever-increasing scale since 1885. Deposits that can be mined on the economical standards of today, however, are confined in a roughly circular area about 30 miles in diameter, generally within Polk and Hillsborough Counties, in the central part of the State. The phosphate deposit, which is in the Bone Valley formation of the Pliocene age, is covered by Pleistocene terrace deposits of unconsolidated quartz sand. The matrix is composed of approximately 1/3 clay slimes, 1/3 silica sand and 1/3 phosphate pebbles. The phosphate occurs usually as rounded pebbles, ranging in size from about 1 inch down to approximately 400 mesh. The phosphate may vary from well- defined hard pebbles to soft weathered rock. The color and character of the phosphate will range from smooth buff pebbles to black and white or "salt and pepper rock." The screen size distribution varies considerably between locations and the recoverable phosphate varies may extend down to the 400 mesh size in some areas, while in others the phosphate may cut off sharply at about 35 mesh.

Jan 1, 1962

By Felicia F. Peng

The naturally occurring aged manganese oxide coated on the granular media was found to have a catalytic effect on the removal of low concentration of Mn(II) (-1 ppm) from drinking water. Applying this principle, a manganese removal technique was developed for removal of higher concentration of Mn(II) (-100 ppm) from mine drainage by using various aged filter media and synthesized granular media with manganese oxide coatings. Laboratory-scale continuous granular media column experiments were conducted to assess the feasibility of manganese oxide-coated granular media for Mn(II) removal from synthesized mine drainage. The removals of Mn(II) were evaluated as a function of operation parameters including solution pH, manganese oxide concentration coated on the media, interstitial velocity, and oxidant concentration of influent. Higher solution pH and/or higher manganese oxide concentration promoted the removal of Mn(II) on the oxide-coated granular media under low interstitial velocity. Addition of sodium hypochlorite as an oxidant in the influent resulted in continuously regenerated oxidized surface to serve as the catalyst for Mn(II) oxidation reaction on the surface of oxide-coated media.

Jan 1, 1994

By H. Copur

Roadheaders have become widely used in underground mining and tunneling operations because they offer the flexibility to excavate soft- to medium-strength rock formations. A critical issue in successful roadheader application is the ability to develop accurate and reliable estimates of machine production capacity and the associated bit costs. Increased pressure to improve productivity and lower costs in the mining and civil construction industries has been the driving force behind the more wide- spread use of mechanical excavation systems. This has caused both industries to move away from the conventional drill and blast methods. Additional benefits of mechanical mining include improved safety, reduced ground support requirements and fewer personnel. These advantages, coupled with recent enhancements in machine performance and reliability, have resulted in mechanical miners taking a larger share of the rock excavation market. Roadheaders are the most widely used underground partial-face excavation machines for soft- to medium- strength rocks, particularly for sedimentary rocks. They are used for development and production in soft rock mining (main haulage drifts, roadways and crosscuts), particularly in coal, industrial minerals and evaporitic rocks. In civil construction, roadheaders are used to excavate railways, roadways, and sewer and diversion tunnels in soft ground conditions. They are also used to enlarge and rehabilitate underground structures. Their ability to excavate almost any profile opening also makes them attractive to those mining and civil construction projects where various opening sizes and profiles are needed. In addition to their high mobility and versatility roadheaders are generally low capital cost systems com- pared with most other mechanical excavators. Because of higher cutting-power density due to a smaller cutting drum, roadheaders can excavate rocks harder and more abrasive than continuous miners and borers.

Jan 1, 1998

By Chen L. Lin, Luis R. M. Bittencourt, Jan D. Miller

Recently research efforts have been made to obtain a high-purity gibbsite concentrate, suitable for first-class alumina refractories, from a Brazilian bauxite ore containing gibbsite (50%), quartz (35%),and kaolinite (15%). Detailed polished-section microprobe analysis was used to describe the liberation characteristics of the ore. Experimental results suggest that the kaolinite liberation characteristics can be described by King's liberation model and that only about 11% of the kaolinite is expected to be liberated at a particle size of 75 µ. Bench-scale experiments for the flotation of gibbsite/kaolinite from quartz using alkyl sulfates as collectors were particularly successful at pH 2, and under appropriate conditions a concentrate containing 93.0% A1 0 (calcined basis) was obtained 2 3 at a gibbsite recovery of about 96%. Subsequently, the more difficult separation of kaolinite from gibbsite was accomplished by kaolinite flotation from the alumina concentrate with a quaternary ammonium salt at pH 6 to produce a high-purity gibbsite product, 97.4% A12O3 (calcined basis), at an overall gibbsite recovery from the bauxite flotation feed of about 90%.

Jan 1, 1990

By S. Chander

A comparison of gold, platinum and sulfide ion selective electrodes was made for determination of Eh in solutions containing hydrosulfide ions as a model system. The comparison was made in terms of the accuracy of the measured response, response time, pH dependence, and reproducibility of measurement. The sensitivity of each electrode towards changes in hydrosulfide ion concentration was measured in terms of the change in measured Eh per decade change in concentration. On the basis of a detailed investigation of the electrode processes occurring at the surface of gold and platinum electrodes, it was postulated that within the pH range investigated these electrodes respond to changes in the hydrosulfide ion concentration in solution. In comparison, the sulfide ion selective electrode is known to respond to changes in the sulfide ion activity in solution. Although the potentials measured with gold and platinum electrodes were mixed potentials, pretreatment procedures can be used to obtain a signal suitable for process control. For control of hydrosulfide ions in flotation pulps, the use of a gold electrode pretreated at 1.0 V with respect to a standard hydrogen electrode is recommended.

Jan 1, 1992

By M. G. Bakker, D. D. Murphy, D. R. Spears

The US Bureau of Mines studied the mechanism of shear flocculation of silica with stearic acid. At pH 6 and 12, shear flocculation of silica was not observed with the addition of up to 4.5 x 10-4 M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations = 10-4 M (22.5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labeled with a doxyl group. The presence of the spin-labeling group did not greatly affect the shear flocculation properties of stearic acid. Adsorption of labeled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicated that the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-5 M (22.5 lb/st). The results are discussed in terms of a possible mechanism for shear flocculation.

Jan 1, 1995

By H. G. Schoenike

A subsequent spin off of the energy shortage is the new life for barite. Over 90% of the barite produced in the world is used as a weighting material in oil well drilling muds. Business is booming; the price of barite has risen; scarcity is imminent, and exploration is going full steam ahead. New barite-producing companies are being formed and many of the barite consumers are considering becoming producers. Prospectors have found a new "love," smaller deposits are being explored, and old deposits, previously rejected, are getting a reappraisal. Even barite tailing piles are being resampled.

Jan 1, 1980

By Stephen F. Munsell

The development of transportation systems for mined materials has historically been characterized by steadily increasing sizes in basic hauling units. This is especially true for open pit mines for which success is dependent upon the economical transportation of vast quantities of material. The depletion of high grade ore reserves has mandated a tremendous increase in the size and complexity of the ore haulage systems necessary for open pit mines, These increased demands were served by rail haulage systems in the early large open pit copper mines while later developed properties opted for the flexibility and lower initial costs of truck haulage. Now, we find the trucks being displaced as large overland belt conveyors tackle the problem of handling these ever larger quantities of low-grade ores with accompanying overburden ratios that can run as high as 10:1 or even 15:1. The basic development of large conveyors with shiftable sections and modular belts has generally taken place overseas, during the last few decades. The coal fields of central Europe proved an ideal testing ground for conveyor innovation because the low density and natural friability of the material created an ideal medium for transporting by belt conveyor. Now these proven ideas are being considered for and implemented into both the soft and hard rock mining industries of the United States.

Jan 1, 1978

By J. Ludden

By Sims Some two years ago we began investigating low coke button bituminous coal for use at our Bound Brook, New Jersey plant as a replacement for anthracite. Since August, 1957 the plant has been operating continously on this coal with the exception of a new 200,000#/hr, cyclone boiler. This study was motivated not from our desire to conduct combustion research, but for the sole purpose of reducing our steam costs, The indications were that the economics were greatly in favor of the use of the bituminous coal. The attempts to reduce the costs have developed some knowledge that has enabled this program to succeed reasonably well as will be discussed later by Mr. Ludden. The production of steam size anthracite is dependent upon either the reclamation of old culm banks or the breakage in the production of the domestic sizes. The anthracite industry has not as yet been able to cut, its mining costs to the point where the production of steam sizes has become a profitable business. This has resulted in two basic problems: (1) A constantly rising price in an attempt to have those sizes carry their share of the cost and, (2) Periodic shortages of supply when the demand is good but the market price prohibits the mining of anthracite to produce those sizes only, These conditions have made the long range forecast appear as though the price would go even higher and/or the supply at times be critically short.

Jan 1, 1958

By W. G. Willson

Low-rank coal (LRC) drying processes are generally categorized by operating temperature, drying environment and type of feed (either sized or ground coal). Within these broad categories, drying processes differ according to the type of drying equipment and methods of quenching and stabilizing the dried products. This paper focuses on the produce quality of various LRC drying processes including conventional low and high temperature evaporative drying and non-evaporative, hydrothermal drying. The former may be preferred if the dried product can be utilized immediately, but moisture re-absorption, spontaneous heating and fines production during handling are problems associated with longer term storage, transportation and utilization. Methods for reducing these problems are discussed. Hydrothermal processing is an advanced technology featuring high pressure, non-evaporative drying, which solves stability problems by producing a liquid fuel.

Jan 1, 1997

By Robert E. Hershey

The phosphate industry is the fourth-ranking mineral industry in Tennessee; it has an annual value of 13,000,000 and a yearly production of almost 2,000,000 tons of phosphate ore. Tennessee, at present, is second in rank of phosphate production in the United States. In accord with the importance of this mineral commodity, the Tennessee Division of Geology, is conducting a continuing study of the industry' and the raw s, materials upon which it is dependent. Of the three type's of phosphate found in Tennessee, the brown phosphate rock of the Bigby faces of the Bigby-Cannon limestone is by far the most extensive in occurrence and is the only type being mined at the present time. Because of the importance of the brown phosphate ores, our Division has mapped , in detail the outcrop pattern of the Bigby facies of the Bigby-Cannon limestone. The geologic mapping was done by Dr C. W. Wilson, Jr. and others under his super-vision and the geology plotted on 7 1/2-minute topographic maps, with scale of 1 to 24,000 or 1 inch equals 2,000 feet. These maps will be available for use in the near future and will be published later-with complete geologic coverage.

Jan 1, 1960

By R. D. Grove

The control of Florida phosphate flotation plants is largely based on the visual observations of experienced operators, both in recognizing good and bad froth conditions and in making judgments about the composition of feed, concentrate and tailing streams. Chemical analyses lag the process by at least two hours and therefore only assist in recalibrating the operators' vision when major deviations occur. An image analysis system has been developed by IMC Fertilizer to improve upon the accuracy and precision of the composition estimation process. It still relies upon the operator taking a representative sample, but provides a measurement in about 15 minutes after that sample is obtained. This paper describes the system and its use and presents comparative results for various process streams.

Jan 1, 1993

By Chin Wei Yang

Linear programming (LP) has proven to be a most effective mechanism for modeling a vast array of practical problems, while the development of LP applications in engineering have been extensive enough to show its advantages and limitations. In this paper: we focus on the properties of the widely-wed linear programming transportation (LPT) model formulated and developed by Koopmans (1) . There have been many models of this type applied especially in the field of energy economics (2-7). Since most of these applications can be linked to the seminal work of Henderson (8), we stall present our discussions based on his work.

Jan 1, 1980

By Andres Salazar, Carlos Delgado Robles, Richard K. Preece

The paper discusses the evolution of the geometallurgical model at the Escondida mine in northern Chile, the world’s largest copper producer. It highlights the transition from early metallurgical forecasting methods to a comprehensive model that includes spatial distribution of metallurgical forecasts. This model helps in planning and adapting to the variability in ore characteristics, such as hardness and mineralogy, which affect processing performance.

Dec 1, 2023

The Montgary pegmatite is located at Bernic Lake in the southeastern Manitoba pegmatite district. 'It has a complex internal structure with several contrasting mineral assemblages. The pegmatite contains a number of potentially valuable miners including spodumene, amblygonite,. lepidolite, zinnwaidite, pollucite and beryl.. The distribution of each of these within the pegmatite is related to the internal structure and controlled by a specific mineral assemblage. Parts of the pegmatite contain a high concentration of spodumene. The pollucite occurrence is of unique character and is one of the largest known deposits of this mineral. The pegmatite is still-like in attitude with a maximum dip of about 15 degrees. Its contents with the amphibolitic wall rocks are sharp and tourmalinized. Mineral assemblages present include perthite-plagioclase-quartz-muscovite, spodumene-microcline perthite-plagioclase-quartz-muscovite, cleavelandite-lithia micas-quartz, quartz-amblygonite, albite, lepidolite, pollucite, and quartz assemblages. The occurrence and relationships of these are described and possible relationships between attitude and internal structure are discussed. Many features of the pegmatite suggest that the deposit formed by crystallization and differentiation of a pegmatitic fluid in a restricted system. These features are discussed. The nature and occurrence of the pollucite, lepidolite and albite assemblages are such, however that it is difficult to visualize them resulting from such a system. These assemblages may be of later replacement origin. The source of the, late, alkali-rich replacing solutions may be unmixing of soda and the rarer alkalis (lithium, rubidium, caesium) from earlier-formed silicates in a manner analogous to the unmixing of soda feldspar in perthites. Various aspects of this hypothesis are examined.

Jan 1, 1959

By Lauro Lacerda

Shotcrete is a highly adaptable and widely used underground construction material at infrastructure and mining projects around the world. In fact, many projects could not have been completed without its utilization. As underground projects became larger the use of mechanized wet-mix spraying gradually replaced manual dry-mix shotcrete applications. This paper details some of the reasons for that and provides information on the equipment and operational factors including safety and productivity required to successfully complete underground shotcrete projects.

Jun 13, 2021

By Todd Kilduff, James Grillo, Shrey Arora

In efforts to improve ingress/egress from the existing subway platforms in PATH’s Exchange Place Station, a new 18-foot horseshoe cross-passage tunnel was constructed by Walsh Construction who retained Kilduff Underground Engineering for design of the initial support system and to install and maintain geotechnical instrumentation. The project presented some unique challenges as a result of the proximity to pedestrians on the platform. PATH service remained uninterrupted, limiting the Contractor to mechanical means of excavation to advance the heading. The logistics proved very challenging for the approximate 100-foot-long tunnel excavated in soft Manhattan Schist. This paper will present the design and construction challenges for the project.

Dec 1, 2022

By I. Cameron-Clarke

This paper describes the design of a wellfield to provide a water supply for a new mine in southern Africa. A hydrogeological investigation was conducted that included the drilling and test pumping of eight wells located within a highly jointed pyroxenite aquifer. The wellfield was designed using a simple probabilistic analysis. This approach allowed the variability of the aquifer parameters to be taken into account. A risk assessment analysis was then carried out to evaluate the level of assurance that a reliable water supply could be provided by the wellfield. The analysis was also used to assess the effects of supplementing the water supply by pumping from nearby flooded workings.

Jan 1, 1992

By Y. FUJII, E. CHANDA, J. KODAMA, D. FUKUDA, M. NISHIHARA, Y. NAKAYAMA, P. SINKALA

This paper describes a creep damage model that was proposed to clarify the rockburst mechanism for the Mufulira underground copper mine in Zambia. Cumulative rock damage was evaluated for the edge elements of each sidewall of the mining drives based on normal stresses by the 3-D displacement discontinuity method (DDM) (Crouch and Fairhurst, 1973). The rockburst occurrences were well hindcasted.

Jan 1, 2023

By F. Daviess

A requirement for geological controls during orebody modeling results from the recognition of heterogeneous geological characteristics and/or abrupt variations in orebody geometries. While purely statistical methods are often sufficient for modeling uniform homogeneous deposits, and the only recourse for many that are extremely complex, geological interpretations can be extremely valuable as controls during the modeling process. The advent of relatively inexpensive, sophisticated graphical computer hardware and software has focused considerable attention on the three dimensional visualization capabilities now available to the mining industry. Orebody geometries can be easily imported into many systems as wireframe or solid models, rendered with shading and color, rotated in space, exploded into composite parts, zoomed into and otherwise displayed to awe any audience. The requirements for an initially meaningful, accurate, geological interpretation are sometimes lost when the focus is on an apparently complex, highly resolved end product. Details of the initial data and sensitivities of modeling assumptions are not always sufficiently scrutinized. Software capabilities have extended the geopoetic license into three dimensions. The new tools, while greatly facilitating model construction and rendering, have done little to expedite basic data preparation and analysis. This paper attempts to briefly summarize the purpose and method of the construction of geological controls. The examples selected are from wire­framing and block modeling; application software processes commonly used in the mining industry today.

Jan 1, 1992