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By Milan Terčelj, Matej Drobne, Urška Klančnik, Peter Fajfar

The study of oxidation behavior of High Chromium Steel material used for surface layer of work rolls was carried out. Specimens taken directly from the roll were subjected to thermal fatigue in the temperature range between room temperature and 500 °C up to 700 °C by using thermo-mechanical simulator Gleeble 1500D. Our observation was focused on the impact of oxidation as a principal mechanism of degradation of the roll’s surface layer - mainly on the characteristics of oxidation propagation in relation to the test temperature and microstructure constituents characteristics of the material. Oxidation is considerably accelerated by certain characteristics of eutectic and primary carbides, i.e. their size (area), composition, morphology, orientation regarding to the water-cooled surface, etc. In the presented paper selected cases where emphasized oxidation takes place are investigated, analyzed and explained. Obtained results thus represent a contribution to explanation of conditions which lead to acceleration of oxidation behavior that in turn can lead to chipping or even early spalling of material from the roll surface layer.

Oct 1, 2019

By G R. Power

A useful way to assess potential productivity of SLC mines is by quantifying tonnes/drawpoint/day to be extracted from the mine. However limited industry information has been published to help mines benchmark this number. This paper assesses industry data which can be used to support estimates of potential productivity from new mines based on tonnes/drawpoint/day. The information used has been extracted from historical production schedules which indicate what was achieved, rather than what was planned. It has been assessed using an algorithm created for the purpose and is presented with discussion of varying definitions of active drawpoints, analysis of the data and inquiry into some of the underlying contributing factors.

Mar 15, 2021

By Haitao Wang, Shen Wang, Dongyin Li, Yongjia Xu, Jinzhao Liu, Xiangjun Chen

The safe and efficient driving of the roadway along the gob is becoming an increasing challenge due to the influence of the integrity and bearing capacity of the side coal and rock mass in the gob under the roof cutting mining mode. The mechanism of protection of the gob-side roadway is shown by modeling the influence of roof cutting and the application of a destress technique on the lateral coal and rock mass zones. The distribution characteristics of stress, displacement, and fracture in the overburden are analyzed by numerical simulation method under the three working conditions. The results indicate (1) construction of row holes and blasting can form artificial structure’s fracture plane above the roadway, which can effectively cut the connection of overburden. The artificial structure’s fracture plane decreases the peak value of the lateral coal body’s support pressure. The peak point and the critical location of the stress reduction area are both transferred to the deep part at the same time, providing adequate space for the gob-side roadway. (2) The stress arch foot in the lateral rock mass rises to the rock layer at the bottom of the roof cutting plane after top cutting, as does the high-pressure area of deviator stress. The fracture plane prevents lateral coal and rock mass instability and limits the negative effects of roof deformation above the gob-side roadway. (3) The triangle slip fracture zone moves to over the roof cutting drilling zone due to the fracture plane, showing a high position compared to its original zone.

Jul 11, 2023

By GUY B. HUNNER

THOSE magnetite ore bodies comprising the Clifton Mines are situated in the south central part of St. Lawrence County, New York, on the western slope of the Adirondack Mountains. The topography is made up of gently rolling hills densely wooded with second-growth maple, birch, and hemlock. Drainage is north and west to the St. Lawrence River.

Jan 1, 1943

By A. Villanueva

The effect of High Pressure Grinding Rolls (HPGR), as a preceding stage to a conventional ball mill circuit at PT Freeport Indonesia?s C1/C2 concentrators, has been studied in terms of downstream grinding efficiency and circuit performance. When milling the product from the HPGR, mill capacity increased by 21% for the same product grind size, when compared to processing similar ore from a conventional crushing circuit. This achievement is a result of several reasons, among them: reduction in feed size (F80), fines generation beyond the proportional reduction in F80, reduction in ore hardness induced by HPGR comminution mechanism, optimization of the recycle system of the HPGR and ball string optimization in the ball mill circuit given the new feed to the mill.

Jan 1, 2012

By Walter Curlook

An atmospheric acid leaching process for leaching nickel and cobalt from highly-serpentinized saprolitic fractions of nickel laterite deposits has been developed and patented [I]. The process involves leaching the highly-serpentinized saprolitic portion of the nickel laterite ore profile in strong sulphuric acid solutions at atmospheric pressure and temperatures between 80°C and 100°C, essentially autogenously, to extract over 85% of its contained nickel content and a large proportion of its cobalt content after leaching times of about one hour. The amount of sulphuric acid used in the leaching process is between 80% and 100% by weight of the finely ground highly-serpentinized saprolite ore on a dry weight basis. The metal values are recovered as intermediate products. Key words: Atmospheric Leaching; Nickel Oxide Ores; Laterites

Jan 1, 2004

By McClelland. John J.

This Bureau of Mines report discusses recent applications of water in-fusion technology to control dust in U.S coal mines and presents recommended guidelines for determining coal seam infusibility. The techniques required to use water infusion are presented in detail. A Bureau case study indicated that water infusion reduced dust levels by 68 pct along a longwall plow face, bringing this section into compliance with the Z.0-mg/m3 Federal dust standard. Similar studies conducted by Occidental Research Corp. under a Bureau contract show water infusion at two longwall double-drum shearer operations produced dust reductions ranging from 38 to 50 pct. Water infusion was found to be cost effective, aver-aging 5 cents per ton.

Jan 1, 1987

By J. J. Botha

As a Demand Side Management (DSM) Project, money was granted for the procurement and installation of a 3-Chamber Pipe Feeder System (3-CPFS) at AngloGold Ashanti?s Moab Khotsong Mine in the Vaal River Area, Orkney. The first submission was done to ESKOM in December 2002 and the contract was signed in September 2006 at a cost of R 57-million with an envisaged reduction in power of 7 Megawatt per month based on a 90% utilization factor. The project was finally commissioned in December 2008. The technology is not new, but the intent of the paper is to share with others the experience gained by using the technology in a deep-level mine in order to reduce overall power consumption.

Jan 1, 2009

By Franklin D. Slagle

Porosity and bulk-and sand-grain-density values were determined for 2,040 core samples of 30 formations from 47 wells in New York, Ohio, Pennsylvania, and West Virginia, and are compiled for petroleum industry use in well-log evaluation and geologic studies.

Jan 1, 1967

By B K. Da, S A. Balaji, G P. Roy, T K. Dutta

The raw material handling complex at the Durgapur steel plant provides iron ore, crushed coke and flux to two sinter plants. Either some facilities were not envisaged or not properly designed before the project stage which caused problems during operation of the plant. The absence of an in situ roll turning facility, used to increase maintenance activities for disassembly, transportation of rolls to central machine shop and assembly of rolls, led to decreased crusher availability and increased activities for the maintenance crew. The provision of a smaller vibro feeder/screen in place of a suitable sized screen caused jamming of the screen deck, adversely affecting screening efficiency and the crushing index of crushed coke. Some design modifications and developmental work was undertaken, such as the development and installation of an in situ roll turning facility in the existing limited space, achieving low feed (0.1 - 0.2 mm/rev), lower cutting speed of 30 - 40 m/minute for 350 BHN hard roll, which was also a difficult engineering challenge to bring within the tolerable limit of vibration. This was successfully achieved. Modifications to the screen deck, introduction of differential speed crushing and modification to the vibro screen and vibro feeder for uniform distribution of feed have been incorporated. These innovative design modifications to the in situ roll turning have led to a drastic decrease in maintenance activities and an improvement in the crushing index. Modifications to the screen have resulted in the elimination of jamming and improved screening. Modifications to the vibro screen before the primary crushers and to the vibro feeder before the secondary crushers have prevented excessive wear in the central portion of rolls, ultimately leading to increased roll life. Incorporation of differential speed crushing has resulted in an increased crushing index and decreased generation of micro fines. All the above modifications have led to distinct improvements in equipment availability, increased roll life and a decrease in maintenance activities and improvement in crushed coke granulametry, ultimately resulting in improved productivity and quality of iron ore agglomeration at the sinter plant. The innovative design modifications mentioned above are discussed in detail in this paper.

Jan 1, 2005

By Steve W. Webb

The Bureau of Mines is researching a new technology for dewatering clay suspensions that consists of flocculation by high-molecular-weight poly-ethylene oxide (PEO) polymer and subsequent removal of water from the floes via a trommel. The minimum amount of PEO required to dewater the clays depends on the ions adsorbed on the surface of the elay particles. Infrared studies were performed on clays with Li+, NH4+, K+, Mg2+, Ca2+, Ba2+, or 8r2+ adsorbed, with and without adsorbed PEO, to develop data to aid in understanding the dewatering mechanism. Hydroxyl stretching modes between 3,400 and 3,250 em-I, associated with water adsorbed on the clay, showed changes in intensity proportional to the ionic eharge-to-radius ratio; that is, the ionic potential. In addition. a water-bending vibration of adsorbed water at 1,630 cm-1 showed variations associated with water desorption. The data are consistent with changes in adsorption of PEO resulting from variation of the acidity of water coordinated with the exchange ions, induced by the variation in field strength of the ions with the ionic potential.

Jan 1, 1986

By R. V. Ramani, C. J. Bise

INTRODUCTION Classification of coal seams as thin, medium, and thick is both subjective and relative and is more a reflection of the statistical mode of the thicknesses en- countered in a mining region. A geological factor more precisely understood as defined than thickness is the inclination of the seams to the horizontal, commonly referred to as the pitch or the dip of the seam. Thick and steeply pitching seams present far more challenges to the ingenuity of the mining men to devise methods for their extraction than the thick and less steeply inclined ones. In a marginal case, where a thick coal seam may be minable by surface or underground methods, the decision bears a close relationship to the technological developments in the mining scene. Near surface thick coal seams are a special gift of nature and are not as wide- spread as the ones that call for the application of under- ground methods. Recent advancements in surface mining equipment have made it possible to surface mine to great depths. Stripping ratios of 30: 1 (cu yd of over- burden removed per ton of coal) have been achieved. The extraction of thick seams which preclude the use of surface methods is the concern of this chapter. Specifically, the objective here is to outline the special technological factors in underground mining of thick coal seams and to illustrate through several case histories the methods that are practiced in the North American continent. For the purposes of this chapter, a thick seam is defined as one which is not readily minable with currently available equipment without modifications to the extraction method or the equipment. At the present time, a thickness of 4.8 m (16 ft) can be considered as the lower limit, although developments in equipment and methods can be expected to push this limit upwards. The data for the case histories were collected from two extended mine visits in 1975 and 1978, and from other published accounts of the mines visited. Reference is drawn particularly to reports by Bise, Ramani, and Stefanko (1976) and Rarnani and Kenzy (1979). THICK SEAM MINING METHODS The various methods of mining thick seams can generally be grouped into three major categories: full face methods, where the entire thickness of the seam is re- covered in a single pass; slicing methods, where the seam is extracted to its full thickness by horizontal or inclined slices either in an ascending or descending order; and caving methods, where the seam is undercut and the en- tire coal seam is recovered by caving the top coal into the excavated cut, or some variations of the basic sub- level caving method. As shown in Table 1, in each of these methods, the coal is removed by either room-and-pillar or longwall methods. Hydraulic mining and transport of the coal in open flumes or in pipelines are also practiced. Addition- ally, the void created by the removal of coal may be filled with a packing material (stowing) except in the caving methods. The pitch (dip) of the seam, particularly when it is greater than 0.26 rad (150), imposes severe operational limitations on mobile equipment. A more detailed general discussion of the methods can be found in Bise et al. (1976) and Vorobjev and Deshmukh (1964). Specific discussion on the many variations of the three basic methods can be found in the papers presented at the international symposia that were held in

Jan 1, 1982

By T Baumgartl, C Gonzales, A Soliman, M Edraki

A soil cover isolates potentially acid-forming (PAF) mine wastes from atmospheric interaction and thereby mitigates acid mine drainage. As a cover that comprises either a single layer or a composite barrier, it essentially manages percolating rain water from flowing into these PAF materials and minimises air flow as oxygen has low diffusivity in saturated soils. However, the availability of suitable soils as cover materials is limited, especially in arid and semi-arid regions where weathering rates are low.This paper investigates the potential use of mine wastes as cover materials in a water-shedding soil cover in north-west Queensland. Four cover trial plots were built using mine wastes as cover materials. Each 2.3 m cover trial plot consisted of a 1.5 m soil cover made up of waste rocks and fines, a 0.5 m drainage layer that consisted of 0.1 m waste rock aggregates and a base layer made up of blended mine tailings. The hydrologic properties of cover materials were determined by in situ measurements and laboratory experiments, which, in turn, were used as input in a numerical model that described the cover’s transient soil moisture profile. The successful performance of the cover is reliant on the long-term stable geochemical behaviour of the substrate used as cover material. Therefore, investigations were carried out to determine the geochemical properties of the cover materials constructed from benign waste rock using static and kinetic tests, with the objective to increase the level of certainty of the material’s benign characteristics. Consequently, the long-term performance of this water-shedding cover design is described in terms of the physico-chemical characteristics of its outflows.CITATION:Gonzales, C, Baumgartl, T, Edraki, M and Soliman, A, ?2014. Mine wastes as cover materials in a water-shedding soil cover in north-west Queensland, in Proceedings Life-of-Mine 2014 , pp 261–270 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By J. A. Kosek

Work has been carried out under Bureau of Mines Contract HO 395132 to develop improved sensor cells for use in direct-reading detectors and diffusion exposure meters. A pumped CO sensor cell was developed which has a shorter response time, improved temperature cycle characteristics, and improved linearity and stability at high CO concentrations. Diffusion CO sensor cells have shown good response level stability and linearity up to 1000 ppm. In addition, a new sensor cell catalyst has been developed for NO2 sensor cells which has a much shorter response time and improved response stability characteristics.

Jan 1, 1982

Professor H.R. Philips was born in South Wales. After graduating with a B.Sc. degree in electrical engineering from the University of Bristol, he joined the National Coal Board's management training programme. Mr B. Moore was born in Coventry, England. He matriculated at Bablake School and then atended Birmingham University, obtaining a B.Sc. Mining Engineering degree in 1953. Professor J .S.J. (J annie) van Deventer matriculated at Swelendam High School. He studied chemical engineering at the University of Stelenbosch, and obtained the degrees of Hons. B. Ing. in 1978 and Ph.D. (Ing.) in 1985. Professor M.D. Brayshaw received most of his education in England but obtained his Ph.D. (Eng.) at the University of Natal. Rock fragmentation by blasting The Third International Symposium of Rock Fragmentation by Blasting will be held in Brisbane, Australia, from 26th to 31st August, 1990. The Third International Symposium of Rock Fragmentation by Blasting is designed to inform delegates on the state of the art in explosives and blasting technology, and to build on the standards of excellence set by the previous symposia in Lulea, Sweden (1983) and Keystone, Colorado (1987). Delegates with an operational, technical, or research focus on blasting will gain from this interactive symposium. Recent journal Mineral resources engineering, edited by C. T. Shaw, T.L. Car, and M. Karmis. London, Taylor & Francis, 1989. Published quarterly. US $107 per year. Risk management The Cost Engineering Association of Southern Africa (CEASA) is to hold its 3rd Biennial Symposium at Indaba, Midrand, on 25th and 26th January 1990. The title of the Symposium is Risk Management in Promotion of Capital Projects. The present political and economic environment in South Africa is characterized by a lack of financial resources, and of technical and management skills, on the part of project owners, designers, and contractors/ vendors.

Jan 1, 1989

By I Grewal, M Lundt

Dense medium separation (DMS) is one of several preconcentration methods used for early waste rejection from run-of-mine ores at relatively coarse particle sizes prior to additional milling and beneficiation. DMS has been used extensively in the coal, diamonds, mineral sands, base metals and iron ore industries to produce either a final product or as a preconcentration step. Laboratory scale and pilot test work at the Met-Solve laboratory in Canada has demonstrated successful separation and upgrading of other minerals such as lead, zinc, copper and lithium based ores using DMS.This paper reviews historical dense media systems, results from the pilot-scale multi-stage DMS Separator “Condor” system, as well as production plants and associated laboratory heavy liquid separation (HLS) test work on various minerals. The mineral systems tested included a lithium bearing ore and a fluorspar ore. Other minerals were tested but are not reported in this paper.Pilot plant test work on a fluorspar ore showed that 41.6% of the mass could be rejected to the tailings stream while 95.3% of the CaF2 was recoverable to the product stream. On a spodumene sample that was tested, it was possible to reject 55% of the mass to tailings while recovering over 90% of the lithium.In recent market conditions and with the decreasing grades in existing ores, preconcentration should be a consideration to maximise the value of certain operations.CITATION:Lundt, M and Grewal, I, 2017. Dense media separation – a valuable process for preconcentration, in Proceedings MetPlant 2017, pp 122–130 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By Ronaldo Santos Sampaio

This paper call attention to increasing ratio of oxygen depletion from atmosphere besides the global worries about CO2 concentration increase in the atmosphere. It highlights the big mistake in considering Carbon Capture and Storage, CCS, as a way to reduce the increasing concentration of CO2 in the atmosphere. As a hypothetical example it presents an existing pseudo-ecosystem of manufacturing that has real windows of opportunity to increase its share in the global materials production industry, even in highly industrialized countries. As a suggestion and example the author point out possibilities to almost fulfill the proposed simple rules to be considered inside an ecosystem of manufacturing utilizing the production of steel via biomass versus fossil coal. A relevant and difficult rule to be attained in a quasi-ecosystem of manufacture is to be a near zero atmosphere oxygen depletion integrated process. The industrial alternatives that utilizes the actual photosynthesis are the ones that can reach a higher ecosystem of manufacture’s index. It is presented an ideal integrated steelmaking process where the gaseous, liquids and solid residues generated in one part of the system are or can be utilized in the other parts of the same system. A potential ecosystem of manufacture to produce primary iron is illustrated in the paper.

Aug 17, 2017

By A. G. Roach

Introduction This paper deals with the operations and plant of the Craigmont Corundum Project, formerly of Wartime Metals Corporation but now under the Mines Section of the Resources Development Branch of the Department of Reconstruction and Supply. Corundum is recovered by the re-treatment of an old tailing deposit at Craigmont, Ontario. Crude concentrates so produced are shipped to the plant of the American Abrasives Company, Inc., at Westfield, Mass., for final processing and distribution to the abrasive industry. The plant was recently described in a paper entitled Craigmont Corundum which was presented by the writer before the Chicago meeting of the A.I .M.E. in February, 1946. General The Project is located on? lots 4 and 5, concession XVIII, township of Raglan, Renfrew county, Ontario, near the village of Combermere, which is on Highway 62. The property is about 135 miles from Ottawa. The general area enjoys a pleasant climate with moderate summer temperatures, though the winters are rather severe, the mercury frequently falling to - 35 deg. F. The excellent boating, fishing, and hunting have made the district a favourite resort for tourists. Lumbering is the main industry. Some farming is carried on, but the soil is poor and much of the land is hilly and rocky. There are no other operating mines in the immediate vicinity, though several 'industrial minerals', including mica, feldspar, nepheline, beryl, socialite, and others have been produced in the area. The district is drained by the York and Madawaska rivers and is generously dotted with large and small lakes. The general elevation is about 1,000 feet above sea level, though numerous hills rising several hundred feet give a rolling appearance to the landscape.

Jan 1, 1946

By Rodnei Graça, Jorge Silva Bettencourt, Lena Virgínia Soares Monteiro, Baruch Spiro, Tolentino Flávio De Oliveira

Abstract - The Vazante Mine is located in the Vazante District, the largest zinc district in Brazil. The Vazante deposit consists dominantly of an unusual willemitic ore. Small sulfide bodies are tectonically imbricated with the willemitic ore, within the Vazante shear zone. Structural styles of deformation and petrographic and isotopic evidence indicate that willemitic mineralization and deformation occurred synchronously during the Neo-Proterozoic. Various generations of hydrothermal veins and hydraulic breccias may pre-date, accompany and overprint the mineralization. Ore-formation temperatures are deduced from stable isotope geothermometry and mineral chemistry of both sulfide bodies and willemitic ore. Temperatures during the main stage of mineralization range from 206°C to 294°C (willemitic ore) and 317°C (sulfides), and reflect the prevailing metamorphic conditions within the shear zone. The fluid from which the gangue minerals of the sulfide bodies precipitated (at 250°C) had an oxygen isotopic average value of ?18O = +19.4‰. This value appears to reflect the interaction of metamorphic fluid with the carbonate rocks of the Vazante formation. At 250°C, the fluid in equilibrium with the vein mineral phases and willemitic ore assemblage exhibits a uniform oxygen isotopic composition, with an average value of ?18O = +11.5‰. The positive linear covariance of ?18O and ?13C ratios of the carbonates is most likely due to the mixing of metamorphic and meteoric fluids. The ?34S values of sulfides indicate a direct crustal origin for the sulfur. It is suggested that the sulfur is largely derived from pre-existing sulfide bodies and has been transported by metamorphic fluids. The willemitic ore may have originated from the precipitation of metal in sulfur- poor fluids under oxidized conditions, within the Vazante shear zone.

Jan 1, 1999

By David R. Hanson

Seismic tomographic imaging, based on the same principles as a medical CAT Scan (Computer-Aided-Tomography). has been used for many years in the oil industry for large-scale subsurface stratigraphic characterization. and has most recently been applied to various structure- and stress-related problems in the coal industry. New developments in signal processing have greatly enhanced the speed, resolution, and range of applications of topographic imaging in underground settings, and recent innovations in data acquisition hardware have further increased data reliability and repeatability. Whereas past structure mapping applications relied on Seismic velocity and/or attenuation tomopraphy within an enclosed seismic source gram receiver array, recent developments in "True Reflective Tomography- (TRT TM) have expanded the application of this technology considerably. For example, in-seam TRT TM seismic reflection tray now he used to image structure, and/or old workings from one general location in the mine face areas of mains and panel developments) well ahead of planned developments largely eliminating the need to probe-hole drill on regular intervals. This new reflective technology bas also been combined with traditional cross-hole seismic tomography-providing a comprehensive, powerful tool for velocity attenuation. and reflective imagine utilizing the same source/receiver array data sets (borehole-to-borehole. borehole-to-entry and entry-to-entry). These new developments in data acquisition and image processing have greatly expanded the variety of applications for tomographic site characterization allowing the mine operator considerable flexibility to cost-effectively characterize previously inaccessible areas of the property. This paper presents examples of 2-D and 3-D .seismic topographic imaging applied to (1) the location of old works in Appalachian room-and-pillar operations and (2) the identification of anomalous zones ahead of mining/tunneling developments these applications demonstrate the state-of-the-art in seismic ground imaging using velocity, attenuation. aril reflection techniques land combinations thereon, and further illustrate the flexibility of data acquisition from a variety of tinning arid tunneling settings. Recent examples are presented from projects in the United States and Europe.

Jan 1, 2000