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By Z Lubosik, S Prusek, M Plonka, B Syrek

"The most commonly used method of thick coal seam extraction in Polish deep mines is multislice longwall (MSL). In MSL stability of goaf in the roof as a result of previous extraction in upper slice is a major geotechnical consideration that must be managed.This paper outlines the results of a wide range of investigations carried out in three longwalls that were in operation in a multislice system using caving with additional fly ash goaf stowing. The longwalls were operated by Katowicki Holding Weglowy SA (KHWSA) in the Upper Silesian Coal Basin of Poland.Examinations were completed on the properties of goaf at the roof of longwalls ie measurements of strength parameters of the goaf material by means of a borehole hydraulic penetrometer, determination of the goaf condition by means of a borehole endoscope and laboratory testing of the caved rock. The results of underground examinations of the loading on yielding arches in the gate roads associated with these longwalls and measurements of vertical and horizontal convergence are also presented.CITATION:Prusek, S, Lubosik, Z, Plonka, M and Syrek, B, 2014. Multislice longwalling for thick seam extraction – properties of goaf in the roof and gate roads behaviour, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 359–366 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By Liu Fan, Shang Yanbo, Wang Zhongming

"Besides valuable metals of Cu, Sn, WO3, Zn, there are S, Ag, CaF2, In and so on in a complex ore deposit in south China (which belongs to Hu Nan Shizhuyuan Non-ferrous Metal Limited Liability). Although it proved reserve amounts to 3.5×107 ton, its crystal character limits its utilization in large-scale. It features complex relationships between valuable minerals, finest crystallized particle size, low-graded valuable metals (Cu 0.30%, Zn 0.5-0.7%, Sn 0.2%, W<0.1%). If only tungsten minerals are considered, it means WO3 grade is too low (the cut-off grade of WO3 is 0.1% in China). Only Cu and Sn minerals are recovered from 2006 and Cu recovery is less than 70%, Sn 15-20%. Other valuable metals of W, Zn, S and CaF2 were lost in the tailings. To make good use of the ore, the technology of fully recovering Cu, Sn, W, Zn, CaF2 and rare metals are in urgent need. After systematic researches, the flow sheet of "bulk flotation of Cu-Zn minerals at first, then Cu-Zn separation, then recovering sulphide by flotation, then recovering iron minerals by magnetic separation, then bulk flotation of Sn-W minerals after desliming" is developed. Furthermore, specific Sn-W collectors of BK411 and BK412 are applied into the processes and better indexes are obtained. The industrial indexes are listed as followings: the content of Cu, Zn, Sn, WO3 of ROM ore is 0.31%, 0.65%, 0.13%, 0.03%; Cu and Zn recovery are 82.23% and 37.79% respectively; 63.76% of Sn and 34.34% of WO3 go into the Sn-W bulk concentrates. Economic benefits are remarkable."

Jan 1, 2014

By M. E. Sirkka

"INTRODUCTIONInco Ltd. has ten operating mines in the Sudbury district. Over the last ten years mining methods have changed at Inco with special emphasis on the introduction of bulk mining replacing conventional mechanized cut-and-f ill and undercut-and-fill methods. At the same time, the technology and size of LH D equipment has also progressed to meet the demands of bulk mining. This paper will concentrate on various aspects of the introduction and operation of electric LHD equipment a t Inco Limited, Ontario Division. BackgroundInco Limited received its first electric 2 cu. yd capacity LHD in July 1975 at Creighton Mine. The unit was tested pulling shrinkage stope muck and then was moved to a mechanized cut and- fill complex on 6600 Level. The electric scooptram received quick acceptance from the operators, due to its quiet operation and low heat generation, in a relatively hot operating environment. Although there are only two of these units operating a t present, this initial favourable experience, both in cost and efficiency, led to the development and purchase of electric scooptrams of the 5 cu. yd size. There are currently eleven 5 cu . yd electric LHDs in operation.The most recent development a t Inco is the move to yet larger electric LHDs in the 8 cu. yd size. The first electric ""Eight"" has now been in operation at Copper Cliff South Mine for over a year. This unit has the distinction of being the first one of its kind in service in North America. At the time of writing, there were ten 8 cu. yd electric ma chines operating in Inco&apos;s Ontario Division Mines, with three on order."

Jan 1, 1989

By Phillips RN

Semi-confined, trachy-andesite sills which overlie the German Creek Seam, within the critical tensile strain zone, form major groundwater hazards to longwall mining at the German Creek underground mines. The water contained in these aquifers is normally neutral, but highly saline. Techniques used to detect aquifers include routine air-lift pumping in exploratory drill holes, downhole geophysical and geological logging and upstage packer testing. Hydraulic constants are calculated from pump-out and pump-in test results. Hydraulic parameters for the calculation of mine inflow rates are determined from pump-out test results because these tests appear to be more representative of aquifer drainage during goat dewatering than pump- in testing. During mining of the first longwall block at Central Colliery, caving fractures intersected overlying aquifers after the longwall had retreated 40m, and mine water inflow rate rapidly increased from less than one litre/sec to 25 litres/sec. The amount of water pumped out of the mine during first panel extraction was 140 megalitres with drawdown occurring over an area of 168 hectares. In the Southern Colliery area approximately 324 megalitres of highly saline water which is actively stored in the Aquila Sill area will be pre-drained from six well points prior to longwall mining. With effective pre-drainage from surface drill holes, maximum inflow rate into the mine during initial goafing can be reduced from 165 litres/sec to about 45 litres/sec.

Jan 1, 1988

By A. Bozorgzadeh, B. M. Jensen, B. N. Koelling, B. R. Murtaugh

"The Service Base mooring system originally consisted of two general types of structures, 19 timber piles cabled together and steel three-legged pipe piles. The St. Louis District fleet moored to the fleet barges which were tied off to shore-side concrete deadman and supported on the landward side by the timber and steel piles. The purpose of this project was to replace the existing floating wharf mooring system at the St. Louis Service Base. The Marine Design Center of the U.S. Corps of Engineers developed a three pile cluster system concept. The clusters consisted of one vertical pile and two batter piles. Piles in rock sockets were selected to resist the uplift loads due to high wind loads on the tall, spare lock gates stored at the floating wharf. This paper focuses on the design of the rock sockets for steel pipe piles with large uplift loads and the lessons learned during the design and construction of this system.INTRODUCTIONBackgroundThe U.S. Army Corps of Engineers’ St. Louis District is located at the critical transition point on the Mississippi River where it is a “locking river” north of St. Louis and an “open river” to the south. The St. Louis District is responsible for maintaining navigation channels on the Mississippi River, the Illinois River and the Kaskaskia River. It is also responsible for the operation and maintenance of five locks and dams within its geographic boundaries.The St. Louis District utilizes a fleet of vessels (dredges, crane barges, motor vessels, and barges) to support the navigation mission identified above. The St. Louis District Service Base, located in St. Louis, Missouri, serves as the base of operations for the district fleet. This riverfront facility originally consisted of a floating wharf, a railroad trestle, and a walkway down the river bank to the floating wharf. Historically, there have been two fleeting areas at the Service Base. The main fleeting area was approximately 965 feet long and consisted of six fleet barges (Figure 1). This area supported the Dredge Potter and its attendant fleet. The upper fleeting area was approximately 1,050 feet long and consisted of various stop log, crane and work barges, dredge pipe pontoons and work flats."

Jan 1, 2017

By N. K. Bohidar

Evaluation of the stability of a structure under given boundary conditions requires accurate knowledge of the state of stress as well as the mechanism of failure at the critical state of stress. This paper represents a part of the research done by N. K. Bohidar during 1965-1968 for his Ph. D. research in Mining Engineering at the University of Utah. It summarizes the determination of internal stress and failure phenomena around cylindrical openings in viscoelastic media subjected to lateral restraint and vertical uniaxial load. The conditions of lateral restraint and viscoelastic nature of the media represent conditions associated with subsurface openings in rocks. The financial assistance provided to the project from the University of Utah Research (Uniform School Fund), W. C. Browning Scholarship Fund, Earth Science Research Fund, and D. C. Jackling Loan and Scholarship Fund is gratefully acknowledged. The authors also acknowledge the assistance of S. Siugh, W. Jones, and K. McCarter during the project.

Jan 1, 1970

By Richards RG

The Australian glass sand industry produces some 2.8 million tonnes per annum of silica sand, of which about 2.0 million tonnes are exported and the rest is for the domestic market. Approximate production rates for each Australian state are listed.The variety of processing methods used in the currently exploited deposits reflects the size, location, and characteristics of the various deposits and the requirement of the end market/s. The industry uses to a large extent equipment developed for the separation of mineral sands, particularly as it applies to low grade heavy mineral deposits, where low cost, high capacity and metallurgically efficient equipment has proved eminently suitable for the production of the low value glass sands.The requirements of the domestic market, as well as those of the present and potential export markets are discussed covering quality requirements, distribution channels and other factors critical to success.

Jan 1, 1990

By Homor N. McDonald, G. Dale Coe, Will H. Coghill

"INTRODUCTION Sporadic beneficiation tests have been made on the Birmingham (Ala.) red iron ores for the last 55 years. Now, gravity-concentration plants are in operation, of tables are in use. A major problem, as seen by the present writers, is to obtain a coarser concentrate and add to the recovery without increasing the quantity of slime. The oily practicable solution found so far is to recover, by means of concentration (hydraulic) classifiers, the coarse concentrate normally lost in the table middling and, by a similar method, to recover middling particles from the table tailings The size and shape of the coarse concentrate Particles combine to cause them to report in the table middling rather than in the table concentrate. Similarly, mineral is lost in the tailing. Because of this, the nature of the ore, the deportment jerking table, plant tests on classifiers and tables, and the suitability of small concentration classifiers to treat table zonal middlings are discussed herein.The work was done by the Southern Experiment Station, Bureau of Mines, in cooperation with the University of Alabama, Tuscaloosa, Ala."

Jan 1, 1935

By G. A. Zeito

Detailed visua1 examination of outcrops was used to ob-tain data on the lateral extent of shale breaks. Thirty vertical exposures belonging to maritie, deltaic and channel depositiorral environrrrents were exatmind, surveyed and photographed. The dimensions of the outcrops ranged from 356- to 8,240-ft long and 25- to 265-ft thick. Shale breaks were found to extend laterally for significant distances. and in some sands terminates by joining other break v much more frequently than by disappearance. Consequently with regard to flaw, a gross sand consisted of both continuous and discontinuous subunits. The degree of continuity of shale breaks as well as the occurrence and spatial distribution of discontinuities were different for the three depositional environments. Statistical eva1uations were performed to determine the confidence level with which estimates derived from outcrops can be applied to reservoir sands. Results of these evaluations revealed that: (I) the lateral continuity of shale breaks in marine. sands is si~nificatit, and the estimates of lateral extent can he applied to reservoir sands with a high degree of confidence (80 to 99 per cent of the shale breaks continued more than 500 ft, with a confidence of 86 per cent); and (2) the tendency for adjacent shale breaks to converge upon each other over small distances in deltaic and channel sands is highly significant (62 to 70 per cent of the shale breaks converged in less than 250 ft, with a confidence of 50 per cent), hut the probable magnitude of the resulting sand discontinuities cannot yet he predicted with adequate confidence. INTRODUCTION Almost all of the efforts devoted to characterization of the variable nature of reservoir sands have been focussed on permeability variations. Among the widely used concepts that have emerged from these efforts are those of stratified permeabilities, random permeabilities, and communicating and noncommunicating layers of different permeabilities. This study is concerned with the presence of interbedded shales and silt laminations. These features are impermeable or only slightly permeable to flow. Therefore, knowledge of the extent to which they continue laterally and the manner in which they terminate within the bodies of gross sands is important for proper description of reservoir flow. Initial field observations made on outcrops revealed that shale breaks and the relatively thinner silt laminae have impressive lateral continuity. They appeared to divide sand sections into separate individual sand layers. Although most of the layers were continuous across the total lengths of the outcrops, some were discontinuous because the- bounding shale breaks converged. Furthermore, the discontinuous layers appeared more prevalent in channel and deltaic sands than in marine sands. Based on these initial findings, a detailed investigation was carried out to determine, quantitatively: (1) the degree of continuity of shale breaks in marine. deltaic and channel sands; and (2) the frequency and spatial distribution of discontinuities in the three environments. PROCEDURE The procedure used to obtain field data from outcrops included visual examination, surveying and photographing each outcrop. The photographs were examined carefully and important outcrop features were traced, measured and recorded. The selection of outcrops for this study was made on the basis that each outcrop should be exposed clearly to permit detailed visual examination of vertical lithology. and it should also be sufficiently long (over 200 ft) to provide useful data on the lateral continuity of lithology. Identification of the depositional environment for each outcrop was made on the basis of bedding characteristics, vertical sequence of lithology and the presence of indicative sedimentary features. Whenever possible, hand specimens of associated shales were collected to determine depositional origin. Almost one-half of the outcrops used in this study required environmental identification; the remainder had already been identified by previous investigators. Several photographs of each outcrop were usually required to cover the entire length of the outcrop. These photographs were taken from one station or several, depending on the terrain, size of the outcrop and distance to the outcrop. A Hasselblad camera, with a standard 80-mm lens and a 250-mm telephoto lens, was used. The telephoto lens permitted photographing outcrops as far as two miles away. Slow-speed films were used. either Panatomic-X or Plus-X. The final operation conducted in the field was that of surveying the outcrops. The distance of an outcrop from a point of observation was determined by a triangulation method using the plane table. The measured distance was then combined with the angle of view of the camera lens to establish a scale to be used on the photographs. Films were processed using standard processing techniques and 4.5X enlargements made. The enlargements of each outcrop were butted together to form a single panorama. Slides were also prepared on several outcrops; these were used whenever greater magnification (wall projection) was required to bring out maximum lithologic detail. The shale breaks and bedding planes in each outcrop were traced on transparent acetate film superimposed on

Jan 1, 1966

Micro-computers have made it practical to install a high-speed acquisition system to collect data from a longwall face in near real-time. By simultaneous data analyses using neural networks and fuzzy sets, information regarding longwall mining performance and underground behavior can be provided and forecasting longwall instability and detecting geological anomalies is feasible. This paper presents details of the application of neural networks and fuzzy sets in developing on-line evaluation of longwall roof behavior. Techniques for interpreting longwall shield pressures and characterizing roof conditions are discussed.

Jan 1, 1996

The article presents an outline of methods and certain results of laboratory tests, underground tests and model tests, aimed at assessing performance of a powered shield support on the floor of low strength parameters. The tests were conducted within the framework of GEOSOFT project co financed by Research Fund for Coal and Steel (RFCR-CT-2010-00001). The described research works were conducted by Central Mining Institute (Glówny Instytut Górnictwa), Janina coal mine and Becker-Warkop

Aug 1, 2013

By William L. Batt

FROM the time the Japs overran the Far East, the United Nations faced a serious military problem in the critical shortage of many raw materials desperately needed to prose¬cute the war on two fronts. For many months this critical shortage threatened substantially to limit the gigantic effort to get shooting equipment into the hands of the fighting men on the far-flung battle lines. Now this crisis has been met. Solvency in raw materials has been achieved. Simply stated, this job of producing solvency has been done by "cutting cloth to fit the garment." This does not mean that we have all the raw materials we need. Unfortunately, a few raw materials are still short, thereby limiting the total production of certain war goods, or making these goods less effective. Where the supply of raw materials is known to be limited, however, substitutions have been made or production schedules have been geared to the amounts available, and an over-all balance has been achieved between various parts of the war-production program.

Jan 1, 1943

By P. A. Riveros

Antimony is commonly found in copper electrolytes and can contaminate the cathode deposit. Several methods, such as ion exchange, solvent extraction and precipitation, have been developed to remove antimony from copper electrolytes. However, past research has been carried out almost exclusively with Sb(III), whereas the presence and behavior of Sb(V) in the electrorefining circuit have been largely ignored. In this study, the behavior of Sb(V) species was monitored and compared to that of Sb(III) species, using specially developed analytical and SEM-EDS techniques. Significant differences in the behavior of the two species were noted. Although the solubility of Sb(III) increases with temperature in synthetic copper electrolytes, the solubility of Sb(V) appears to be constant over the range from 30 to 80°C. Whereas Sb(III) forms several crystalline oxy-sulphate compounds, Sb(V) appears to remain as an amorphous oxide. Both Sb(III) and Sb(V) are extracted by aminophosphonic resins, and Sb(III) is readily eluted by HC1 or complexing agents. By contrast, concentrated HC1 elutes Sb(V) inefficiently and complexing agents, such as EDTA and tartaric acid, do not elute Sb(V) to any significant extent. This observation implies that in industrial practice, unless special measures are taken, Sb(V) will accumulate on the resin, eventually impeding the ion exchange process.

Jan 1, 2007

By Lawrence W. Teufel

Knowledge of in situ stress and natural fracture distribution at depth improves our ability to stimulate and produce low permeability reservoirs. The focus of this study is three closely spaced, 2.5 km deep vertical wells in the Piceance Basin of Colorado. The wells were completed through the tight lenticular and blanket gas sands of the Mesaverde Group. In situ stress directions and magnitudes were determined from hydraulic fracture tests and anelastic strain recovery measurements of oriented core. The distribution, orientation, and characteristics of natural fractures in the subsurface were determined from detailed observations of over 1300 m of core, of which 400 m was oriented. Stress measurements clearly show that horizontal stresses are strongly influenced by lithology. In a sandstone/shale sequence at a depth of about 2.0 km in situ stresses in sandstone formations are anisotropic, with the average ratios of the minimum and maximum horizontal stresses to the overburden stress being 0.82 and 0.96, respectively. In sharp contrast bounding shale formations are lithostatic. This stress contrast between sandstones and bounding shale formations could act as a barrier to hydraulic fracture propagation during stimulation and impede vertical fracture growth. Natural calcite-filled fractures are present in over 7 percent of the core, with several horizons having a much higher frequency of fractures. Fractures are found primarily in sandstone. The fractures have a strong preferred orientation of N 1060E[+]110, which is aligned with the maximum horizontal stress and direction of hydraulic fracture propagation. The interaction between a well developed fracture fabric and anisotropic stresses in sandstone formations produces a permeability anisotropy, with the maximum permeability aligned with the fracture fabric and maximum horizontal stress.

Jan 1, 1986

By Moffatt G

Approval to operate Longwall No. 7 at Appin Colliery in 1979 was granted pursuant not only to the usual statutory provisions, but also that an adequate means of drainage of methane gas be incorporated. A methane drainage plant was subsequently designed and constructed some two km from the pit top at the site of the Colliery main upcast and down cast shafts. Modern plants of this nature are completely automated using programmable controllers and computers to provide control and management reporting functions. Complex mechanical systems are installed to extract the gas and in handling and storage processes. Gas utilisation plants exist which can generate power from methane. These plants are further enhanced by harnessing waste heat produced in the generation process. The installation, automation control and monitoring of these plants incorporates many facets of engineering from high voltage power supply and computer technology to complex gas handling procedures used in gas compression storage.and generation of electric power.

Jan 1, 1982

By K. E. Beu

THE integrated intensity X-ray method of meas-uring retained austenite concentrations in hardened plain carbon or low alloy steels as proposed by Averbach and Cohen1,2 has the advantages of being a highly sensitive and precise quantitative method. The various phases of this method have been studied and several modifications have been developed which aid not only in reducing the time required per determination, but which also increase the possible accuracy of the method. A fundamental step in the original calculation procedure is to plot V.A(?) curves for austenite and martensite and to obtain VM/VA ratios from these curves.&apos; In taking this ratio the absorption factor A (8) drops out since it is constant for a. given diffraction angle 8. The reason for eliminating A(?) in this manner is because it is apparently assumed

Jan 1, 1953

By Bing Song, Fei Xi, Xuewei Lv, Kai Zhang

The electric arc furnace process is a common method to produce high TiO2 slag from ilmenite. The pre-reduction process was proposed in recent years in order to reduce electricity consumption. In order to enhance the pre-reduction degree, high energy ball milling was proposed to improve the specific surface area of the ilmenite prior to reduction. In this study, the carbothermic reduction behavior of milled ilmenite concentrate was investigated. It was found that the ball milling method can result in a higher reduction rate and improved metallization of iron. The metallization of iron increased with increasing the time of ball milling. The metallization of iron with milling reached 89.49% when the time of ball milling was 70 min., while the FeO content decreased with 70 min. of milling from 11.84% to 4.76%.

Jan 1, 2014

By M P. Cipold, J F. Bachmann, C C. Bachmann, J Ha

Knowledge of fuel qualities is of ultimate importance for the efficiency of chemical plants or power stations. Although most blending yards are equipped with automatic samplers and the derived samples are processed in the laboratory, the quality variation of the blended product may still be strong. This is caused by several reasons. First of all the process of sampling, crushing, dividing and analysis is time consuming. Results are available only with a delay of two to 24 hours. During this time blending is operated without knowledge of the main parameters. Conveyors with high throughput require expensive sampling systems capable of handling samples which are representative. The frequency of sampling needs also to be high in order to be representative. This results in high maintenance costs and also downtime of the sampling system.Online analysis of bulk materials has matured over time and today it can supplement but not replace laboratory analysis. As an example, J&amp;C Bachmann has realised a coal quality monitoring system on the coal supply of a South African coal processing plant. The plant consumes ~42 Mt of coal per annum. The blending yard consists of two sets of three heaps where coal of six different mines is blended according to the factory’s requirement. From there, the blended coal is fed to the factory on two different belts.In 2010 the plant installed a TEXAS X-ray fluorescence analyser as a trial. It was tested under different conditions on several belts before the customer decided to install six TEXAS analysers on the feed belts to the stackers and two more analysers on the reclaimer belts. All analysers are installed directly on the belt and not on a substream.During the test period blending strategies were developed in close cooperation between the customer and J&amp;C Bachmann. The use of the analysers in conjunction with the blending model has proven that the variation of the reclaimed coal quality was decreased significantly, which results in increased process performance and significant cost savings.CITATION:Bachmann, C C, Bachmann, J F, Cipold, M P and Ha, J, 2017. Online quality control of a coal blending yard, in Proceedings Eighth World Conference on Sampling and Blending , pp 125–128 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By M. du Plessis, D. F. Malan

"The aim of any mine design is to ensure that the excavations remain stable for the period they will be in use. Various pillar systems are used to ensure that underground stopes remain stable and that mining activities do not affect the surface infrastructure through either surface subsidence or seismicity. Intermediate-depth platinum mines make use of in-stope pillars designed to fail while the pillars are being cut at the mining face. The pillar stress exceeds the loading capacity and the pillars crush as a result. The aim of the paper is to provide an overview of in-stope crush pillars. This will include the application, behaviour, function, mechanism, impact, and design of a crush pillar system."

Jan 1, 2015

By Robert S. Setren, Jeffrey L. Ambs

The disposable diesel exhaust filter (DDEF) system developed by the U.S. Bureau of Mines and Industry cooperators for heavy-duty permissible, diesel-powered haulage vehicles, effectively reduces in-mine diesel particulate matter concentrations up to 95%. However, there are concerns about the hazards that exist when the filter is used in situations for which it was not designed. This work investigates the exhaust gas temperature limits to which the filter elements can be exposed without posing a safety or health hazard, such as 6re or off-gassing toxic compounds. A filter approved by the Mine Safety and Health administration and after-market filters were evaluated under varying engine exhaust conditions to determine if after-market filters pose an unacceptable hazard when used in a DDEF system. Filters were laboratory tested at engine exhaust temperatures ranging from 77°C to 290°C. Of the seven filter types tested, six appeared suitable for use on water scrubber-based cooling systems and two appeared suitable for use on dry heat exchanger type exhaust cooling systems with exhaust temperatures up to 150°C. Any filter elements used as exhaust filters on permissible diesel machines must be approved by MSHA for that application. Mine operators who wish to use an after-market filter element should request an MSHA field modification. MSHA will work with the mine and filter manufacturer to ensure its use in this exhaust system application does not pose a health or safety hazard.

Jan 1, 1995