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By Minghui Li

China is the largest coal producer in the world. In 2012, the coal production in China is 3.65billion tonnes, accounting for approximately 49% of global coal production. The raw coal production in 2012 was 3.8% more than the year 2011. 56% of total raw coal has been washed. The increase in raw coal production also promotes technology to be developed and brings separation capacity become larger and larger in coal processing in China. At present, over 40 extra-large scale coal preparation plants (each plant has capacity of more than 10 Mtpa) are in operation in China, the largest one is 32.5 Mtpa. Heavy medium separation are widely used in new built coal preparation, the washing limit for thermal coal feed lower and lower, the equipment selection tends larger which brings the whole washing system simplified, the local equipment developed and manufactured are more and more used. By discussing designs of several typical thermal coal preparation plants and coking coal preparation plants in China, this thesis introduces the current design of China?s extra-large coal preparation plants, and sums up the prevailing design features and trends of extra-large coal preparation plants.

Aug 1, 2013

By Jan E. Stache

Commercial software programs are being utilized to create and maintain a mine subsidence database in conjunction with the U.S. Bureau of mines research on mine subsidence in Illinois. A three-year survey net of monitored structures in an Illinois subdivision was entered as textual information (attributes), on an existing AutoCAD drawing. These attributes can be optionally displayed on the corresponding drawing or extracted as a text file for import to a database program. The database program, dBASEIV, allows combinations of multiple database files for extensive querying capabilities. Subsurface database files can be merged with surface database files to enhance the effectiveness of surface response analyses in mine subsidence research. The geographic information system (GIS), pcARC/INFO, was chosen to integrate existing AutoCAD drawings and dBASEIV database files into a relational database with a graphical representation. The relational database allows users to update either the graphical representation or the database, with the changes being reflected automatically in its alternate format. The increased capacity, through use of a GIS, to query combinations of database files and have the results reflected graphically has significant potential for expediting mine subsidence research.

Jan 1, 1986

By R. A. Franks, J. C. Edwards, L. Yuan

To determine the critical air velocity for preventing smoke rollback, diesel-fuel fire experiments were conducted in the National Institute for Occupational Safety and Health’s (NIOSH) Pittsburgh Research Laboratory’s Safety Research Coal Mine. Such information is necessary for preplanning and implementation of ventilation changes during mine fire fighting and rescue operations. The fire intensity varied from 50 to 300 kW depending on the fuel tray area. Airflow in the 2-m- (6.6-ft-) high, 2.9-m- (9.5-ft-) wide coal mine entry was regulated during the course of each experiment. The airflow was measured upwind from the fire as an average over the entry cross-section with an ultrasonic airflow sensor and was recorded dynamically with a mine monitoring system. The extent of smoke reversal was monitored with light-obscuration monitors, ionization smoke sensors and visual observations. Experimental results for the critical air velocity for smoke reversal as a function of fire intensity compared very well with model predictions based upon a computational fluid dynamics fire dynamics simulator.

By C. David Mann

Metal prices continued to improve in 1964, resulting in the opening of new mines and re- activation of old ones. Larger and deeper shafts are being bored. At the AEC's Nevada Test Site, a 72-in. diam shaft is being bored to 3200 ft. In New Mexico a 1650-ft shaft was bored with a 48-in. bit, then reamed to 124 in. to 935 ft, and 102 in. to 1650 ft. Deviation was only 26 in. In California a shaft sinking machine has been developed which combines drilling and mucking equipment into one mobile, integral unit.

Jan 2, 1965

By H. H. Otto

Fourteen years ago, J. B. Warriner presented before the Institute a paper on anthracite stripping,' describing the progress of stripping in the Anthracite Region from its beginning with an old quarry stripping at Summit Hill, which was operated more than a century ago, through various types of strippings used in 1917. This paper will briefly review the status of anthracite stripping methods from 1917 to the present day and describe in detail the stripping operation of The Hudson Coal CO. at Clinton collicry. It is not intended as a review of the work in the district—that would require a much longer paper. History and Statistics Mr. Warriner said, in part: "The sizes of shovels have gradually increased until now 70 and 80-ton shovels are the rule and larger equipment is coming in." He also referred to a large electrically operated dragline which weighed about 225 tons and had an operating radius of 125 ft. In 1917, a number of strippings used shovels of various sizes, ranging up to the 60 Marion and Bucyrus 70-C railroad type. Material was hauled away in narrow-gage side dumpers, usually of 4 or 5 cu. yd. capacities. Star-type churn drills with 4-in. bits were generally used for drilling purposes. Since 1917 wages in the anthracite field; have increased, but the higher operating costs of strippings are now being successfully combated by continuous improvements in stripping equipment, such as the development of the caterpillar or crawler shovels, the use of larger cars, better drilling equipment, the introduction of shovels of increased capacity and the adoption, in a number of instances, of standard-gage equipment for transportation. In 1918 another large dragline was introduced in the southern fields, which had been in service in the Middle West and is in use today, dipping vertically about 180 ft. to raise coal out of a stripping. About 1918, small shovels with caterpillar traction were introduced. In 1922 the 6-in. well drills began replacing the 4-in. drills, with an attendant saving to the operators. About the same time A. E. Dick placed the first pair

Jan 1, 1931

By P. V. Roundy

PUBLIC lands in Florida were first withdrawn from entry by President Taft on July 2, 1910, as a conservation measure because of their possible phosphate content. The reserve thus established was subsequently modified by further withdrawals and by restorations, so that on Jan. 1, 1934,' it contained 66,796 acres, of which only a small part had been defi-nitely classified. The reserved land was in scattered parcels, ranging from less than 40 acres to 320 or more, distributed in many counties. For administrative purposes and for final disposal of any of the numerous parcels, mineral classification of the land is legally necessary. In 1934 and 1935 the United States Geological Survey, under two successive grants from the Public Works Administration, prospected some 83 tracts of these lands in Polk County, comprising in all about 3300 acres, and six tracts comprising 240 acres in Citrus and Marion Counties. The tracts in Polk County were all in the so-called land-pebble field and the others in the hard-rock field. The Survey field party was under the direction of P. V. Roundy, from whose unpublished report the material in this paper is largely taken. The foreman of the prospecting crew was J. H. Wingate of Zephyrhills, Fla. The individual tracts were identified through the cooperation of the General Land Office, by transitman Hugh B. Crawford. This prospecting work fitted well the classification adopted for Public Works projects in general: it could not he done on any considerable scale under the Survey's usual appropriations; it gave employment to unem-ployed labor; and it may be expected ultimately to repay the Government in royalties more than the cost of the exploration.

Jan 1, 1937

By W. C. McBee

Over the past several years the Bureau of Mines has developed a sulfur concrete (SC) technology in which chemically modified sulfur is mixed with suitable mineral aggregates to produce construction materials that are resistant to corrosion by acids and salts. Modified SC materials have been tested in actual operating conditions in 50 corrosive process environments at 40 commercial plants. SC components ranging from small test coupons to 4-ton acid sump tanks were fabricated and installed at plant locations where chemical corrosion was destroying conventional concrete materials. Through cooperative agreements with several companies, floors, retaining walls, and foundations were cast in place us-ing SC materials, then monitored for resistance to corrosion and retention of strength properties.

Jan 1, 1983

By A. E. Belton

The individual projections for large mines in the Pittsburgh coal seam in northern West Virginia are discussed with emphasis on roof control and ventilation requirements. All four mines use continuous miners with panel belts and rail for main line haulage. Both development and retreat-type mining are covered. There are a variety of mining projections being used currently in northern West Virginia. To discuss each would be impossible, so an arbitrary cross section has been selected in an attempt to indicate a fair degree of representation. Four mines, hereinafter referred to as Mines A, B, C and Dl will be discussed separately. The greater part of northern West Virginia coal production is mined from the Pittsburgh seam. This is the seam worked by all the mines discussed here. Although the coal bed outcrops at the eastern and southernmost points, these mines are all working in a depth ranging from 400 to 1400 ft below the surface. Some steep gracles have been encountered but are only considered local in nature; the overall average dip of the seam is 1 1/2 % northwest. In each of the operations the particular mining scheme used has proved advantageous, since they have been designed to satisfy particular equipment and/or physical condition requirements. So regardless whether such projections utilize a partial or full recovery principle, the productivity performances appear better than average. MINE A Full retreat is the basic mining approach for mine A, although current mining is primarily in the entry-driving stages to expand territory in preparation for pillar work. Only one section unit now on retreat. The average clean coal production at this mine is 7000 tons per day. Initially, a ripper-type miner was used for development at this mine. But with a rather weak roof overlying the coal bed and the greater horizontal span left at the top by a ripper machine, roof control became a critical problem. Even though roof bolts were used concurrently in the mining cycle for initial support, the majority of the roof in these entries

Jan 1, 1962

By Naohiro Kurokawa

Isa Limestone Quarry with an annual production capacity of 18 million metric tons is known as the largest limestone deposit in Japan located in the mountainous region about 20 mile northwest of Ube City, Yamaguchi Prefecture, Japan adjacent to Isa Cement Factory to which it belongs, and which constitutes a mainstay of Ube Industries? cement operating division. Isa Cement Factory is equipped with a N.S.P. kiln of capacity of 3 million metric tons per year, which is the largest of its type in the world. Geographically, it is situated in the south- western tip of the Mainland of Japan (Mid City, Yamaguchi Prefecture) and is bordered by the scenic Akiyoshi Karstic Plateau which is world famous for its huge stalactite grotto.

Jan 1, 1982

By Frank van der Meer, Lea Quincke

"High Pressure Grinding is applied to achieve size reduction of the particles by inter-particle breakage and to generate micro-cracks in the product particles as a contributing factor in e.g. leaching or mineral liberation. As alternative to classification, a closed circuit operation for HPGR can be established by product recycling, where a proportion of the coarser edge material and parts of the center material are split-off to be recirculated to achieve a finer final (center) discharge product for subsequent processing steps as ball mill grinding or beneficiation. As a result of the product recycling, the content of fines in the feed material increases and may affect the grinding efficiency in terms of production of fines and the generation of micro-cracks in the particles. In the scope of this paper, the effects of the proportion of fines in HPGR feed on grinding efficiency and micro-crack generation were evaluated. Grinding tests were executed with different feed size distributions, from a fines-void situation (truncated feed) to a fines-abundant situation (high product recycle). The evaluation of grinding efficiency and generation of micro-cracks was done by particle size analysis, Bond Work Index tests, impact tests on HPGR feed and products, and X-ray computed tomography of single product particles. This publication summarizes the main aspects of the outcome of these investigations."

Jan 1, 2014

At Cliffs Natural Resources Ltd (CNR) crushing and shipping sample stations, precisions are estimated for the sampling, preparation and measurement stages of iron ore sampling in accordance with ISO 3085 (2002). In this Standard, gross duplicate samples are prepared at each of the three stages, yielding eight measurement assays. Appropriate calculations of the differences between assay pairs are then made to estimate precision of each stage of sampling. The International Standard for checking precision in iron ore sampling, ISO 3085 (2002) prescribes a method for identifying outliers that is ambiguous and possibly inappropriate. The procedure also makes an unnecessary implicit assumption, that the differences between assay pairs are normally distributed. The Anderson-Darling statistic is used to demonstrate that in some cases the assay pair differences have distributions significantly different from normal. When applied at CNR as specified, the Standard leads to precision estimates well below the expected values, thus overestimating the sampling method's capability and limiting the opportunity for real process improvement. This paper suggests an improved method of estimating sampling, preparation and measurement precision. A bootstrap procedure is used to estimate confidence limits for the calculated precision estimates. The proposed method would be suitable for testing blasthole precision. The discussion is supported by extensive simulation modelling of realistic data.

Mar 1, 2010

By A. A. Bilgin

The prevention of acid mine drainage (AMD) in situ is more attractive than down-gradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied to an abandoned coal mine pool in Pennsylvania. The pool had a pH of 3.0 to 3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by the enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

Jan 1, 2007

By A J. Burchell

The introduction reviews the tunnelling carried out in Singapore since the early 1980s. Between 1983 and 1990, Phases 1 and 2 of the mass rapid transit system were constructed. These included some 20 km of bored and cut and cover tunnels together with 18 underground stations. Some particular points of interest in this massive project are briefly commented upon. Reference is also made to other underground or underwater schemes undertaken during this period such as the proposed large caverns project and the submerged tunnel to Pulau Seraya. A description of the subsurface works, now under construction in Singapore, follows. This includes an all underground North-East railway line 20 km long with 16 stations. At a budget of US$ 3 billion, this is a major civil engineering undertaking. Another project is the extension of the railway to Changi Airport which involves 3.5 km of twin tube tunnelling together with a major underground station which is fully integrated into the airport terminals. An on-going program of further major railway extensions over the next 10 to 15 years is in place and an outline is given of some of the most important underground sectors. Other proposed projects such as the underground roads system and the deep level sewers are briefly described. Together they demonstrate the very significant volume of underground construction scheduled for the next century in Singapore.

Jan 1, 1999

By A. Wieniewski

The observed progress in technology of non-ferrous ores enrichment and condition of machines and equipment in the ores concentrators on the one hand have brought a possibility and on the other resulted in necessity for introduction of modernization actions. Positive results of investigations into influence of chemical modification of selected products of enrichment process on copper ores enrichment results gave possibility for implementation of chemical-flotation technologies of ores enrichment. The substantial development in flotation machines structure has contributed to modernization of flotation process resulting in increase of enrichment efficiency. The paper presents the idea and results of chemical modification of difficult in enrichment semi-products in the technology of copper ores enrichment and the results obtained after application of the modernised technology. The structure of large-volume flotation machines used in various stages of flotation and current situation in modernization of flotation process in copper ores concentrators are also described. The paper presents industrial-scale results of flotation after application of modified flotation reagents of collector group. Introduction of modifiers into the widely used xanthates resulted in increase of copper recovery in concentrate.

Jan 1, 2014

By B. H. Eccleston

Experimental data were obtained from two medium-duty diesel engines derated to qualify for use in underground mines. Gaseous and particulate emissions from these engines were measured and results provide information on the effect of exhaust treatment devices on the emissions. The devices in the study were a catalyst, a particulate trap, and an exhaust gas cooler of the water scrubber type. Emission levels of carbon monoxide and hydrocarbons were observed to be very low in comparison with emission levels of comparable engines in full-rated operation. Oxides of nitrogen and benzo(a)pyrene content of the exhaust also were found to be somewhat low in comparison with previous findings. For particulate reduction, the combination of a particulate trap and a scrubber was observed to be the most effective combination tried; in some cases, over 60 pct particulate reduction was effected by the trap-scrubber combination.

Jan 1, 1981

By Marcelo Rebellato, Beatriz Pereda, Beatriz Lopez, Pello Uranga

The classical application of Nb microalloying in the development of thermomechanical processes for flat products has been related to its suitability to enhance strain-induced precipitation and get a pancaked austenite prior to transformation. As new steel grades or new lay-outs are being developed, more complex metallurgical conditions need to be evaluated. In this context, Nb microalloying, alone or combined with other microadditions, needs to intervene in a more controlled way in additional steps of the thermomechanical process, besides its conventional strain-induced precipitation role. For example, the hardenability enhancement associated with Nb to properly achieve lower temperature transformation products, demands a proper balance of the Nb amount precipitated during rolling and the one remaining in solid solution. Similar effects are also sought when the final available Nb is used to increase strength through precipitation hardening. This manuscript evaluates how changes in the rolling strategies affect the interaction between Nb(C,N) precipitation and austenite recrystallization at different steps of the rolling process. As the possible interactions between parameters intervening simultaneously are quite complex, the application of microstructural models helps to properly define the best austenite conditioning combined with the convenient amount of Nb in solution, as a function of the final property requirements. Along the manuscript, several strategies will be discussed for the case of hot rolling of flat products comparing both normal and coarse initial austenite grain sizes.

Oct 1, 2019

By E. A. Holbrook

RESEARCH, primarily, is finding out the truth. Research applied to engineering opens the door to new principles and processes, the application of. which benefits mankind in a material way. The engineer believes that investigation instituted with the primary view of making the results directly applicable to the industries is the highest type of research. Coal is essentially the basis of modern industrial civilization; therefore, any, considerable research pertaining to coal must link itself to the industry by, practical application of the results of the research. In other words, all investigational work connected in any way with coal leads to conclusions that permit a better understanding of the origin, nature of occurrence, composition, better and safer mining, more careful preparation, or greater efficiency in utilization of coal. Modern engineering research has been fostered essentially by universities and in the laboratories of institutions of learning. Coal problems that lend themselves to solution in the laboratories have been first attacked and are perhaps the farthest toward solution. For example, a great amount of research work has been carried out with the various phases of chemistry connected with coal. On the other hand, the equally important problems connected with methods of mining have received but little attention, primarily because their solution involves the continued use of a great and expensive laboratory, which is none other than the mine itself. As many of the problems already solved have had chemistry as their background, so many of the problems unsolved have physics as their background; there are also unsolved problems that deal in- coal economics. Even psychology must be called upon in future coal-mining research as a basis for solving those great problems that deal with human relationships. In general, considerable advance has been made in coal research dealing with chemistry, not so much progress has been made with problems having physics and engineering as a background, while there is a tremendous range of untouched problems that deal essentially with business and psychology.

Jan 9, 1919

By Sherwin F. Kelly

NEW trend in geophysics has been uncovered in these depression years, made evident through the thinning cloak of commercial activity, which, in better times, would have completely obscured it. I refer to the increasing use of these methods for geological investigations by federal and state geological surveys. This is a trend that has been gathering momentum not alone in the United States, but abroad as well. Thus, in Poland, the Geological Survey has been playing an increasing role in geophysical work since 1927, and now has- its own geophysical department. The government petroleum producing organization of Argentina has its Geophysical Commission; Brasil boasts a completely equipped geophysical department in its Mineral Production Service; the government of Chile has contracted with commercial companies for geophysical surveys; Peru is planning an intensive program of geophysical prospecting in its petroliferous regions; and Canada has, for several years, cooperated with

Jan 1, 1935

By T. Bhambhani, J. Jankolovits

Sphalerite flotation using copper sulfate has been performed in the industry for decades and the mechanism of Cu activation is well established. Despite its ubiquity, many practical questions surrounding copper sulfate persist. It is not clear how iron selectivity is achieved in zinc circuits given the propensity of iron sulfides to be activated by copper. Also, the large variation in copper sulfate dosages across different plants and ore types cannot be explained. Lastly, Zn flotation with greatly reduced copper sulfate dosages attracts significant interest and has been demonstrated in certain laboratory settings, but no information is available on why those laboratory solutions have not been adopted in plant practice. Flotation studies are presented that demonstrate that Zn flotation with very low copper sulfate dosages is possible when using certain novel collectors that are not practised in the industry. However, these reagent schemes are impractical because of a heretofore unappreciated and critical role that copper sulfate plays in Fe rejection. With both very low and standard copper sulfate dosages, copper sulfate influences both Zn flotation and Fe rejection. The results highlight the multifaceted role of copper sulfate in zinc flotation and the need to holistically consider complex systems’ behaviour to understand flotation reagent mechanisms and optimise plant performance. Keywords: Sphalerite flotation, metal activation, copper sulfate, iron rejection

Jan 1, 2020

By J. J. Jakosky

THE fundamental hydrodynamic principles governing the production of oil from wells have been carefully studied and evaluated by many investigators. These prior studies are quite complete and cover virtually the entire field of oil production and recovery.1 One of the most impor-tant measurements in production studies is that of the bottom-hole pressure at various rates of production.2 It is the purpose of this paper to outline the technique and economics of fluid-level measurements as applied to pumping wells and to review briefly other methods for obtain-ing bottom-hole data. The applications of bottom-hole pressure or fluid-level measure-ments are based on simple hydrodynamic principles. Under equilib-rium conditions, pbh = hd + pg + pch [ l] when pbh = bottom-hole pressure, lb. per sq. in. absolute, h = height of fluid in well, ft., d = average fluid density, lb. per sq. in. per foot, pg = weight of section of gas column 1 in. square from fluid level to casing head, pch = casing-head pressure, lb. per sq. in. absolute. In words, equation 1 states that the bottom-hole pressure is equal to the weight hd of the column of fluid plus the weight of the column of gas between the fluid and the casing head plus the casing-head pressure. At moderate rates of flow, the rate of production is approximately proportional to the difference between the reservoir, or static bottom-hole, pressure and the flowing or producing pressure; i.e.: Q = c(pr - pbh) [2] pr = the reservoir pressure, c = the constant of proportionality. However, at production rates approaching zero and also at high rates the proportionality may break down. By combining equations 1 and 2 the

Jan 1, 1939