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By Philip C. Good

Unweathered low-grade calcareous phosphate rock of about 20 percent P205 grade was beneficiated by a procedure in which contained carbonates were decomposed by calcination at about 1,000° C. On quenching the hot calcined rock in water, major impurities passed into a slime phase which was mechanically separated from a coarser concentrate fraction. Phosphate rock of two major types was beneficiated in batch-scale studies yielding concentrates containing 31.3 to 38.5 percent P205 at recoveries ranging from 54.8 to 86.0 percent. The samples were from two major deposits in India. Processing information gained was utilized in extending the work to a continuous-flow system, processing phosphate rock at rates up to 157 kilograms per hour. Superphosphate exceeding 16 percent water-soluble P205 was prepared from concentrate derived from continuous-flow processing.

Jan 1, 1976

By Jannie van Deventer

"Innovation in the minerals industry has been lagging behind comparable industries like oil and gas. An incremental innovation culture that tolerates long lead times between invention and adoption has been exacerbated by a research grant structure that inhibits radical idea generation. Entrepreneurs who can make the link between ore source, technology and finance will cause a shift in innovation culture and open up substantial opportunities in the minerals industry of the future. By extrapolating existing trends in technology within and outside mineral processing, a crystal ball vision of future innovation is shaped with the aim to lower energy and water demand, reduce CO2 emissions, decrease operating and capital costs, reduce environmental impact, and secure a social licence to operate. Advances in nanotechnology, advanced materials and biotechnology will impact mineral processing, but the initiative for technology transfer must come from mineral processors. Laminates of graphene oxide can offer efficient filtration and separation media, while microfluidic devices will be used for desalination, solvent extraction and analysis. Substantial progress is expected on benign lixiviants and separation agents, such as nanoscale supramolecular hosts that can serve as high-capacity, selective and recyclable ligands and sorbents, and solid aminobiphosphonate-based adsorbents. Radical ideas for the recovery of precious metals from non-assayable ores and the generation of energy above unity will be adopted in selected minerals projects. In-situ mining in which microbes generate lixiviants at mineral surfaces will simplify processing circuits. Specific ores will be subjected to microwave processing and electropulse liberation to enhance recovery. Ultrafine grinding using devices of low energy consumption will be done mainly dry, followed by dry separation. New flotation cells will remove efficiently either coarse particles or ultra-fine particles, with mineral surfaces being modified not just by new reagents but also by selective microbes. Innovation in mineral processing indeed has a bright future."

Jan 1, 2014

By A. C. Johnson

The T. L. shaft of the Eureka Corp., Ltd., near Adams Hill, Eureka, Nev., was sunk in 1954 and 1955 to permit exploration and development of the lead-zinc-silver ore that had been indicated by drilling. This paper describes the sinking of the 4-compartment, vertical shaft to a depth of 1,127 feet and includes pertinent details of equipment, methods, and costs. A shaft crew of 10 men, supplemented by 13 hoistmen, topmen, carpenter, and shop crewmen, sank and timbered the 1,127 feet of shaft in 630 workdays. Total labor per foot of shaft was 107.95 man-hours. Supplies per foot of shaft included 20 pounds of explosives, 1.61 pounds of drill steel, and 200 board-feet of timber. Power consumption, including that required for pumping, averaged 3,726 kw.-hr. per foot.

Jan 1, 1958

By J. V. Thompson

The Powderhorn complex as a source of perovskite (calcium titanate) containing about 1.5% rare earths has been examined in several recent feasibility studies. Much promising exploration and process research has been done in recent years. This paper is presented with cautious optimism and with the acknowledgment that there may be some technical and economic areas yet to be explored. The Powderhorn carbonatite and alkalic stock in Gunnison County, Colorado, lies about 203 airlines km southwest of Denver at an elevation of 2450 to 2750 m (see Figures land 2). All of the mineable ore bodies are owned by Buttes Resources Company of Houston, Texas.

Jan 1, 1990

By C Li, K McDonald an, T Nicholson, C Brown

The relative reactivities of chars prepared from different coal samples at temperatures in the range 500 to 1150¦C were determined by measuring the rates of metallisation of a standard ilmenite concentrate. The results have been interpreted in relation to different measured physical and chemical properties of the chars. Char reactivities were found to correlate with the maximum specific surface area (SSA) of the chars, obtained from plots of SSA versus temperature. Weathering of coal samples gave higher reactivities which correlated with higher SSAs. Experiments using recycled chars showed that the high internal SSAs developed during earlier reduction reactions provide no benefit in terms of increased metallisations. The important role of char hydrogen contents in controlling low temperature metallisation rates was demonstrated. Chars prepared from different rank coals had the same hydrogen content when prepared at the same temperature. Ilmenite metallisation rates had a linear dependence on the hydrogen content of the chars. Large differences in the slopes of the metallisation versus H2 content curves for different chars were interpreted in terms of SSA variations and catalysis of the gas reactions by dispersed metallic iron particles in the chars. A simple test based on magnetic separation of the char was shown to give an indication of enhanced reactivity due to contained metallic iron.

Jan 1, 2001

By Christopher Mark

Successful longwall gate entry design requires control of both vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses, which are generally tectonic in origin, can be highly destructive during the development and headgate phases of longwall mining. The goal of this paper is to present the current state-of-the-art in detecting and controlling horizontal stresses. The information presented was collected through site investigations at 45 U.S. longwalls and an international literature review. The paper begins with a discussion of the present knowledge of regional in situ stress fields in the U.S. A review of available underground stress measurements from coal mines is presented, along with data collected by structural and petroleum geologists. The combined evidence indicates that a persistent ENE-EW trending stressfield is present throughout the eastern coalfields. Experience with horizontal stress in longwall mines is addressed next. The paper focuses on the northern Appalachian region, where the effects of horizontal stress have been most evident. Three case histories are discussed in detail, and the solutions each developed are highlighted. Observations made in the Southern Appalachian, Alabama, and Illinois coalfields are also described.

Jan 1, 1991

By M. Normandin

The performance of various polymers and other macromolecules used to flocculate red mud particulate materials in the Bayer process can be evaluated on the basis of their efficiency to achieve adequate settling velocity and turbidity level, The Jar Test is widely used in the mineral industry to determine the efficiency of solid-liquid separation processes, particularly for gravity settler of the Bayer process. However, a high level of variability is found in the data obtained by this methodology, In this study, different parameters of the cylinder test procedure are evaluated to determine their role in the overall variability of the method, As demonstrated by laboratory testing, the overall variability can be considerably reduced by good laboratory practices.

Jan 1, 2005

By Robert P. Vinson

The U.S. Bureau of Mines evaluated a light-scattering technique for discriminating between spherical and nonspherical particles. This evaluation was a three-step procedure. The first step required collecting light-scattering data for a variety of particles. This was accomplished with a particle analyzer called the DAWN-A. The DAWN-A measured the scattered light intensities of individual particles at a forward scattering angle of 40°. These DAWN-A measurements of individual particles are called scattering signatures by the Bureau researchers. The second step in this evaluation was to calculate a sphericity index number using the scattering signatures produced by the DAWN-A. The sphericity index number can range from 0 to 1. A calculated sphericity index of 1 would show that based on the intensity of scattered light, the particle was a perfect sphere. The third and final step of this evaluation was the comparison of the calculated sphericity indices of the various particles. Comparing these indices made it possible to discriminate between the nearly spherical waterdrops and the nonspherical coal and rock dust particles.

Jan 1, 1993

By P Joyce, D R. Cooke

The Dinkidi Cu-Au porphyry deposit is situated in the Caraballo Range of North Luzon, Philippines. Although comparatively small, Dinkidi has unusually high gold grades with drilling by Climax-Arimco Mining Corporation delineating a 110 Mt orebody at 1.2 g/t gold and 0.5 per cent copper. The magmatic-hydrothermal evolution of Dinkidi records a distinctive switch in mineralisation from an early orthoclase-dominated Au-rich assemblage, typical of alkaline porphyry systems, to a later quartz stockwork Au-Cu rich assemblage typical of most calc-alkaline to shoshonitic porphyry systems. The early orthoclase-dominated stage is associated with the intrusion and crystallisation of a variably-textured clinopyroxene-syenite dyke that contains high-grade (5 - 20 g/t) gold mineralisation. We consider this dyke to be a Cu-Au porphyry analogue to the pegmatites found in granitic systems. Dinkidi is hosted within the Early Miocene Didipio Igneous Complex. This alkaline igneous complex is comprised of early unmineralised gabbros (pyroxene-plagioclase cumulates), clinopyroxenites (pyroxene cummulates), diorites and monzodiorites that have been intruded by a large, weakly mineralised monzonite pluton. The Dinkidi deposit is located at the southern margin of the monzonite pluton. Mineralisation is hosted within a composite monzonite stock. Within the stock, an 800 metres by ~200 metres (plan section) elongate monzonite stock (Tunja Monzonite) predates and hosts the bulk of the Au-Cu mineralisation. This has been intruded by the thin (10 to 30 m wide), highly mineralised variably-textured magnetite- and clinopyroxene- phyric syenite pegmatite (the Balut Dyke). The youngest phases of the composite stock are leucocratic quartz-monzonite porphyry (Quan Porphyry) that grades texturally, in its core, into a post-mineralisation crystal-crowded quartz-syenite (Bufu Felsite). The late-stage Bufu Felsite is inferred to be the source of much of the Cu-Au mineralisation. The Didipio Igneous Complex has intruded a sequence of Late Oligocene alkaline andesitic lavas and volcaniclastics and overlying potassic dacitic lavas. Whole rock geochemical analyses indicate that the intrusions and the potassic dacite lavas in the surrounding region are co-magmatic. Five main stages of hydrothermal activity are recorded at Dinkidi. An unmineralised K-silicate (biotite-magnetite) alteration assemblage formed during the intrusion of the Tunja Monzonite stock. The diorites surrounding the stock display intense selectively pervasive biotite and magnetite alteration and are cut by an extensive network of orthoclase veins and monzonite dykes. The orthoclase-dominated assemblages of Stage Two carry substantial high-grade Au mineralisation and are associated with the intrusion of the Balut Dyke. The emplacement of this unusual dyke is associated with emplacement of pegmatitic clinopyroxene-orthoclase-magnetite¦sulphide dykes, localised orthoclase flooding along the margins of the dyke, and subsequent emplacement of an extensive orthoclase-actinolite-bornite¦chalcopyrite-fluorite stock-work, and development of widespread selectively pervasive actinolite alteration. The main stage of Au-Cu mineralisation at Dinkidi is intimately associated with the intrusion and initial crystallisation of the leuco-monzonite porphyry (Quan Porphyry) and emplacement of a quartz stockwork followed by carbonate-sulphide deposition and intense vein-related sericite and carbonate alteration assemblages. The quartz stockwork formed synchronous with the deposition of the æBugoy QuartzoliteÆ, a very coarse grained mosaic of quartz-orthoclase-perthite along the walls and top of the crystallising intrusion. Stage 3 was terminated by crystallisation of the distinctively vuggy Bufu quartz-syenite phase in the core of the intrusive, with associated antiperthite veins, and the subsequent explosive brecciation of the roof of the intrusion, forming a quartz-fragment breccia from the Bugoy Quartzolite. Retrograde metasomatism during Stage Four was intimately associated with the emplacement of extensive, late-stage carbonate, silica and zeolite veins and widespread selectively pervasive carbonate alteration. The last hydrothermal stage at Dinkidi, Stage 5, is comprised of strong selectively pervasive clay alteration and is associated with fault-related brecciation of the Dinkidi stock.

Jan 1, 1999

By William L. Young

I think I should let you in on one of Canada's best-kept secrets, if you will promise not to tell it all over the place. Believe it or not, good, honest, enterprising capitalism is still alive and flourishing north of our common border, and I am living proof that capitalism is still working for the little guy. My personal story of mining development in Canada isn't all that rare -- you've probably heard something like it from other areas and other days several times -- but my case brings it up-to-date. I would like to Tell you briefly the history of Northumberland Mines Limited, a contemporary case of individual enterprise getting a mining operation underway. And if I can do it you probably can too.

Jan 1, 1981

By Ken J. Brouwer

Stillwater Mining Company commenced construction and development of the East Boulder underground mine in 1998. This new PGM mine is situated adjacent to the East Boulder River approximately 35 miles south of Big Timber, Montana. Project planning and development incorporated detailed collaboration between the regulatory agencies, concerned citizens and mine personnel. A unique ?good neighbour agreement? was established with a local environmental group who have become actively involved in the review of ongoing site development and the implementation of environmental and compliance monitoring. Environmental management systems allow for integrated management of tailings, waste rock and water in order to minimize surface disturbances and to prevent adverse impacts to the East Boulder River. Long-term site development plans contemplate implementation of comingled waste rock and paste tailings. Water management capabilities allow biological treatment of all excess mine water in order to reduce nitrogen loadings prior to land application disposal by means of spray evaporation, snow making and land application. The comprehensive waste and water management plans have also been integrated with staged mine development and interim reclamation requirements.

May 1, 2002

By L. S. Harner

This paper which describes the milling practice at the Golden Cycle mill is one of a series of similar papers being prepared by the United States Bureau of Mines. The mill of the Golden Cycle Corporation, formerly known as the Golden Cycle Mining and Reduction Co., is located at Colorado Springs, Colorado, and has been operated since 1907. It is now and has been from its inception almost exclusively a custom mill.

Jan 1, 1933

By D. Paktunc, S. P. du Preez, J. P. Beukes, P. G. van Zyl, A. Jordaan

"The chromium (Cr) content of stainless steel originates from recycled scrap and/or ferrochrome (FeCr), which is produced mainly by the carbothermic reduction of chromite ore. The oxidative sintered pellet production process is one of the most widely applied FeCr processes. The supplier of this technology specifies that recycling of chromite-containing dust collected from the pellet sintering off-gas and fines screened out from the sintered pellets (collectively referred to as pre-oxidized chromite fines) should be limited to a maximum of 4 wt% of the total pellet composition. However, the results presented in this paper suggest that recycling of such fines up to a limit of 32 wt% of the total pellet composition may improve the compressive and abrasion strengths of the cured pellet. In addition, electron microprobe and quantitative X-ray diffraction (XRD) analyses demonstrate that chromite grains present in the pre-oxidized chromite fines consist, at least partially, of crystalline phases/compounds that will improve the metallurgical efficiency and specific electricity consumption (i.e. MWh/ton FeCr produced) of the smelting process. Introduction Stainless steel is a vital modern-day alloy that is well-known for its corrosion resistance, which is mainly due to the inclusion of chromium (Cr) (ICDA, 2013). Stainless steel is mostly produced from recycled scrap and ferrochrome (FeCr), a relatively crude alloy of Cr and iron (Fe). FeCr is predominantly produced by the carbothermic reduction of chromite, a mineral belonging to the spinel group characterized by the unit formula [(Mg,Fe2+)(Al,Cr,Fe3+)2O4] (Haggerty, 1991; Paktunc and Cabri, 1995; Tathavakar, Antony, and Jha, 2005). Although Cr can occur in 82 different minerals, chromite is the only source of new Cr units that can be exploited in commercial volumes (Motzer and Engineers, 2004). Approximately 95% of mined chromite is used in the production of various FeCr grades, of which high-carbon and charge grade FeCr are the most common (ICDA, 2013)."

Feb 1, 2019

By Richard A. Shulkosky

The American Iron and Steel Institute (AlSO, in conjunction with the U.S. Department of Energy (DOE) jointly funded the development of a mechanical properties model for Hot Strip Mills. INTEG process group, inc. validated an enhanced version of the model under a project funded by the AlSI/DOE Technology Roadmap Program (fRP). The Hot Strip Mill Model (HSMM) version 6.0 allows users to easily set-up their mill configuration, simulate a rolling mill schedule and calibrate the model for a variety of grades of steel. Starting from reheat furnace drop out, the model simulates roughing mill stands (reversing and continuous), heat retention equipment (coil box and covers), finishing mill stands (tandem and Steckel mills), the run out table and the mill exit area. The HSMM uses a series of physical models to calculate both the thermo-mechanical and the microstructure evolution of steel being processed in a hot mill to predict its final mechanical properties. The enhanced HSMM was validated using a multitude of samples from several steel companies. Excellent agreement was obtained for tensile strength. The supporting steel companies have utilized the model for a variety of practical applications. Keywords: Process Modeling, Microstructure Evolution, Mechanical Properties

Jan 1, 2003

By James W. Estep

The sulphur shortage that has occurred in the past two years has directed attention more and more toward sour natural gas reserves, Wellhead values of sour gas vary widely depending upon the acid gas composition, location, market conditions, and necessary processing charges. Preparation of a saleable residue gas is considerably more involved and expensive than that normally encountered in treating a sweet gas. Recent revisions in sales gas specifications have increased capital costs and processing charges. The presence of hydrogen sulphide and carbon dioxide in a natural gas contributes to shrinkage factors that may approach 50%. Fuel required by the gas sweetening process and sulphur slant tail gas incineration also contributes to a further reduction in the volume of residue gas available for sale. The additional processing facilities involving gas sweetening, mercaptan removal, expanded utilities, sulphur recovery and sulphur handling, all demand additional operating and maintenance staff. A favorable sulphur market under certain conditions may justify the processing of sour gas whereby sulphur is either a by-product or a co-product, Five typical cases involving different compositions of sour gas are presented for evaluation. Capital costs, operating problems, and operating costs are presented in detail for full economic evaluation

Jan 1, 1967

By Simons W.

The object of the paper is to describe the standards of quality that should be specified in ordering material ordinarily required for colliery use, and also the qualities most suitable for particular purposes. Tables are presented of British Standard tests for wrought iron grades A, B and C, Admiralty tests for iron in chain, the quality of material for wheels and axles, and the composition and mechanical properties of wrought iron, Armco (ingot) iron and drawbar-gear steel. (Paper presented at the North Staffordshire Institute of Mining and Mechanical Engineers' general meeting held in Stoke-on-Trent, March 27th 1916, Mr. John Gregory, President, in the chair)

Dec 1, 1916

By B. K. Mishra, B. Das, L. Panda, D. S. Rao

"The dissolution behavior of lateritic nickel ore containing 1.2% Ni, 40.6% Fe, 9.5% SiO2 and 9.59% MgO by sulfuric acid was investigated. The ore was characterized adequately by different techniques such as chemical analysis, scanning electron microscope (SEM), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), thermal analysis and Fourier transform infrared (FTIR) spectroscopic measurements. The characterization results did not reveal any distinct mineral phase for nickel; it was associated with mineral phases like goethite, hematite, chromite and serpentine in various proportions. The beneficiation studies by hydrocyclone, magnetic separation and flotation did not enrich the nickel value. Reduction roasting followed by magnetic separation indicated only 2%Ni with 28.9% yield. Consequently, the recovery of nickel values from the lateritic ore by acid leaching under different conditions was studied. The kinetics of leaching obey the first order rate equations. The recovery of nickel was found to be influenced by temperature. It was observed that at an acid concentration of 2M, leaching temperature 363 K, time 240 min and solid-to-liquid ratio of 1:10, it is possible to leach out more than 95% Ni.IntroductionThe demand for nickel is ever increasing. Nickel is used to impart specific properties to steel, titanium and aluminium, and also is used in petrochemicals, catalysts, batteries, etc. It has been estimated that nickel oxide ores account for about 70% of the world nickel reserves. However, most nickel is sourced from sulfide ores. Nickel is extracted from sulfide ore by size reduction, followed by flotation to obtain a nickel-rich concentrate. The concentrate is then pyrometallurgically processed by smelting to produce a nickel-rich matte after discarding an iron-rich slag. Due to the increasing demand for nickel in stainless steel and other alloys, nickel is also extracted from many secondary sources. The recovery of nickel from oxide ores is now gaining momentum, and more exploitation of this ore is being attempted by advanced as well as environmentally feasible, cost-effective techniques. Dalvi et al. (2004) has reported that, due to the increase in demand, the world nickel production from laterites is expected to increase every year from the current level of production. In recent years, investigations of the use of low-grade ores, spent catalysts, clays, etc., have intensified to meet the market demand and also due to a shortage of high-grade nickel bearing ores (Al-Mansi and Abdel, 2002; Baba et al., 2009; Ismail et al., 2011)."

Jan 1, 2015

By L. K. Sinclair

In situ leaching of copper has the potential to deliver low-cost recovery for soluble copper deposits of sufficient permeability. In order to provide key inputs for modeling of the in situ leaching process, bench scale test work can be used in conjunction with geochemical software to identify key leaching and precipitation reactions. A case study is presented in which a series of flow-through acid leaching tests were conducted on drill core sections from a porphyry copper deposit without crushing or grinding. Concentrations of copper and other key elements were monitored in the recirculating leach solution over several months. A geochemical model of each leaching test was prepared using Geochemist's Workbench using a combination of diffusion-controlled and reaction-controlled rate mechanisms. Key reactions included leaching of chrysocolla, iron oxides, and plagioclase. The model was able to simultaneously satisfy the evolving chemistry of the recirculating leach solution, mineralogy of the head and leach residue, measured acid consumption, and leaching rates for key minerals reported from previous laboratory studies. Opportunities and limitations for scaling up the model to simulate the commercial wellfield are discussed.

Jan 1, 2015

By J. S. Malesky

"INTRODUCTION The Airdox method of breaking coal utilizes compressed air under high pressure and was developed to replace explosives. It is used in Illinois and Indiana mines to a large extent and also has been introduced in mines in a few other States.ACKNOWLEDGMENTThe author gratefully acknowledges the information and photographs furnished by the Cardox Corp.HISTORYIn the early 1920's, with the adoption of mechanical mining in States where on-shift shooting was prohibited, it became desirable to develop some means of breaking coal from the face without the use of explosives. At that time it was thought that a pressure of 20,000 pounds per square inch would be necessary to break the seal. It was impossible to obtain a compressor that would develop this pressure therefore, the 'patentees developed and applied the Cardox method, which utilizes liquid carbon dioxide as the blasting medium."

Aug 1, 1948

By John A. Organiscak

The Bureau of Mines conducted a survey of eight shearer longwall operations to identify factors that affect respirable dust generation from longwall roof supports. The longwalls surveyed were in coal seams located in different geographic regions of the United States. Data were collected on mining (geologic) conditions, support design, operational characteristics, and amount of respirable dust generated from roof supports. Analysis indicated that mining conditions are the main factors that affect the generation of dust during roof support movement. Both roof strength and depth of cover above the coal seam showed relationships with the amount of support dust generated. Several practices are currently employed to effectively control roof support dust; however, some of these controls are limited. More research and development is needed to improve dust control technology for longwall roof supports.

Jan 1, 1985