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By G. H. Gronhovd, W. H. Oppelt

Complete gasification to produce synthesis gas for manufacture of synthetic chemicals and fuels offers possibilities for utilization of the vast lignite fuel deposits in the U.S. The design of a slugging, fixed-bed, pressure gasification pilot Plant is described. Results are presented for initial operation of the plant at moderate pressure and using low-temperature char as fuel. Gasification of solid fuels is becoming increasingly important in the future overall energy picture, both in this country and abroad. Snythesis gas from gasification of coal consists chiefly of carbon monoxide and hydrogen, and after suitable purification and modification this gas can be used in the production of synthetic ammonia, methanol, higher alcohols, and synthetic liquid fuels, or as a reducing gas in the metallurgical field.' Most synthesis gas used in this country is made from natural gas, petroleum oils, and refining tail-gases, but the direct gasification of coal will become more attractive as costs of petroleum oils and natural gas increase.' A gasification process designed for use with brown coal and lignite was developed by the German Lurgi Co. prior to World War 11. In this process a fixed bed of lump-sized fuel is gasified with steam and oxygen at pressures ranging from 370 to 440 psi. Effective heat exchange between the ascending high-temperature gases and the descending solid fuel results in low gas outlet temperatures, high thermal efficiency, and favorable oxygen consumption. Lurgi gasifiers are used commercially for the production of synthesis gas or as a substitute for coal gas in many countries, including Germany, Czechslovakia, Great Britain, South Africa, Australia and Pakistan.3-6 The chief disadvantage of the conventional Lurgi gasifier which operates under nonclinkering conditions is that large quantities of excess steam must be supplied with the oxygen-steam mixture to reduce the temperature in the fuel bed below fusion temperature of the ash. Most of the steam leaves the gasifier undecomposed with the product gas and, after cooling, produces large amounts of dilute liquor. Evaluation of fixed-bed gasification experiments using dry-ash removal indicated that by increasing the oxygen concentration in the oxygen-steam blast the temperature in the combustion zone could be raised high enough to operate under slagging conditions. 7-8 Operation of a fixed-bed pressure gasifier under slagging conditions would reduce the steam requirements and the volume of waste liquor and would increase the steam decomposition, the overall thermal efficiency of the process, and the rate of gas production per unit cross sectional area of the gasifier. Because the Lurgi gasification process, modified for slagging operation, offered possibilities for efficient gasification of American lignite, the Bureau of Mines decided to investigate the process on a pilot-plant scale at the Grand Forks, N. D., Lignite Research Laboratory. DESIGN Description of Pilot Plant: A flowsheet of the Grand Forks slagging gasification pilot plant is presented in Fig. 1. The gasifier unit consits of the coal lock, the gas generator, and the slag lock. The fuel, which is periodically charged to the coal lock, moves by gravity flow into the generator and is continuously gasified by an oxygen-steam mixture introduced at the bottom of the gasifier. Molten slag is formed at the hearth and flows through a central taphole into a water quench bath. The slag-water slurry is periodically discharged from the slag lock. Process steam is generated and superheated in separately-fired, oil-burning units. Oxygen is supplied to the gasifier from a gas storage bank located some distance from the pilot plant. The capacity of the oxygen storage bank is about 130,000 standard cu ft at 2200 psig. Liquid oxygen is delivered by truck and is converted to gas during the filling operation. The superheated steam and oxygen are metered separately, then mixed and fed to the gasifier tuyeres. The gas generator is surrounded by a water jacket. The steam formed is separated in the steam drum and then discharged to the gas offtake, thus equaliz-

Jan 1, 1961

By Alexandra Anderson

A computational fluid dynamic (CFD) model has been developed using ANSYS Fluent 17.0 to help identify areas of high wear within the refractory lining of a secondary lead reverberatory furnace. Once a base case simulation was validated using data from an operational furnace, areas of potentially high refractory wear were determined through the calculation of the temperature and velocity distributions within the furnace and on the hot face of the refractory lining. The CFD model was used to assess whether the predicted areas of high refractory wear could be minimized through changes burden geometry. The results showed that shape of the burden geometry greatly affected the overall flow patterns and heat transfer within the furnace.

By David S. Robertson, Richard F. Douglas

"Uranium is a lithophile element of relatively low natural abundance. Concentrations of uranium form through processes of erosion and sedimentation, and over 90 per cent of the western world's uranium ore reserves are in sedimentary rocks.Proterozoic quartz-pebble conglomerates contain about 60 per cent of the known uranium reserves. These are all similar in appearance, in mode of distribution and in manner of origin. They carry uranium minerals and/or gold and abundant pyrite. Their unique distribution in Huronian time required a pre-existing crust well enough evolved to have plentiful quartz and abundant gold, uranium and pyrite. The materials of value were deposited as detrital heavy minerals prior to the appearance of an oxidizing atmosphere in late Proterozoic time.Epigenetic uranium deposits occur in arkosic sedimentary rocks through the entire geological column. About 30 per cent of the western world's known ore reserves are in _these rocks. This type of deposit is particularly prominent in semi-arid parts of the United States, having yielded most of the uranium ore produced and containing nearly all of the known reserves.The Western States type"" of deposits occur in lenticular, permeable stream-laid sedimentary rocks. The de-posits are believed to have been precipitated from moving ground water at locations where plant debris or other organic matter had accumulated. The uranium may be derived from volcanic sediments, which are commonly associated with the units containing the ore, or it may be leached from exposed granite surfaces or from granitic debris which forms the sediments.A significant part of the world's uranium resources are in black shales and lignitic rocks. The lignites that contain uranium are virtually valueless as potential sources of heat. Uranium concentrations at levels such as to be potential sources of by-product uranium occur in many phosphorites.Reworked sediments may provide uranium in pegmatites and vein-like deposits."

Jan 1, 1970

By P. D. Chamberlin

Agglomeration for the heap leaching of gold and silver ores can be defined as the process of attaching fine ore particles (less than 100 mesh) to coarser particles so the fines are immobilized and uniformly distributed throughout the heap, thus making the heap more porous and uniformly permeable to the flow of a leaching solution. Agglomeration techniques and equipment to be described include drum and disc agglomerators, stockpile and belt agglomeration, and the use of vibrating deck and reverse running conveyors.

Jan 1, 1986

By P Stephenson, G Mosher, M Berry, C Arnold, P Stoker

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Globally, private minerals companies considering the transition to a public company and entrepreneurs looking to create a new public company through, for example, an initial public offering or by a reverse takeover have many options. For companies with assets around the Pacific Rim, there are arguably five key stock/securities exchanges that actively promote international minerals company listings, and these are located in Australia, Canada, Hong Kong, Singapore and the United Kingdom.Listing on any of these exchanges requires a range of technical, commercial, financial and legal documentation. Each exchange has specific rules and requirements for technical documentation to support the listing process. Once listed, each exchange also has specific rules for technical information to meet ongoing compliance requirements. The nature and detail of this documentation differs for the five exchanges.This paper presents statistics on the minerals company listings on each exchange and provides an overview of the technical documentation required to prepare for an initial listing and ongoing compliance.CITATION:Berry, M, Stoker, P, Stephenson, P, Arnold, C and Mosher, G, 2015. Technical considerations of public listing and ongoing compliance for minerals companies , in Proceedings PACRIM 2015 Congress, pp 101–108 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By C. Clark, J. Seymour, D. Benton

"National Institute for Occupational Safety and Health NIOSH is conducting research on jackleg use and related accidents in underground metal mines. This paper provides an analysis and overview of jackleg drill usage, accidents, operational characteristics, and alternatives, based on information from injury reports, legacy research, stakeholder input, and published literature. Jackleg drills are involved in more ground fall accidents in underground metal mines than any other drill. Jackleg-related injuries are most prevalent at the face in the course of installing initial ground support. Alternatives to jacklegs for drilling and bolting under incomplete support in narrow underground openings are not yet available. Small mechanized bolting equipment needs to be developed to address jackleg-related accidents and improve safety at mines where jacklegs are being used. JACKLEG DRILL Description The term “jackleg drill” is a generic name for a class of handheld, rotary, percussion rock drills that are equipped with an attached reaction leg to provide stability and thrust for the drill (Figure 1). All of the drill and leg controls are located near the operator’s handle at the rear of the head portion of the drill. Jacklegs are classified according to the bore size of their pneumatic pistons which normally range from 6.03 to 8.26 cm (2.375 to 3.25 in) [Kurt, 1982; Clark, 2012]. Jacklegs typically weigh 460 N (103 lbs), but their weight can approach 535 N (120 lbs) after they are fitted for operation with drill steel and air and water hoses [McKibbin and Clark, 2001]. In underground mines, jackleg drills are commonly used to drill 3.8-cm (1.5-in) diameter holes 1.83 m (6 ft) deep in rock. Application The jackleg drill is primarily used in underground mines when the size of the ore body, the ground conditions, or the mining method do not permit large openings to be mined using mechanized equipment (e.g., narrow vein mining). Jacklegs are used to drill blast-holes for explosives and also holes for installing ground support. These versatile drills are used in nearly all phases of mining including exploration, development, production, and maintenance [Kurt, 1982; Williams et al., 2007; Chen and McKinnon, 2012]. The jackleg is used to drill holes in rock using drill bits attached to hollow steel bars called drill steels (rotary percussion drilling). After the hole is drilled, the jackleg can be used to install different types of ground support components, depending on the ground conditions and the specific ground support measures that are needed. For example, the jackleg can be used to install expansion-anchor rockbolts or resin-grouted rockbolts using the drill’s rotary-motion feature. On the other hand, the jackleg can also be used to install friction-type Split-Set™ rockbolts using the drill’s percussion (hammer-motion) feature. As shown in Figure 1, various washer-like bearing plates can be installed along with these bolts to provide additional ground support and to help secure surface control products, such as wire mesh and shotcrete that are in turn used to retain small, loose material between the bolts [Clark, 2012]."

Jan 1, 2016

By João Carmo Vendramim

A oxidação da superfície de peças, ferramentas, moldes ou matrizes construídas em ligas ferrosas tem larga utilização na indústria. As aplicações podem ser as mais diversas, tais como simplesmente atender às questões estéticas, proteção da superfície contra a corrosão, ou proteção contra a interação química com outros metais. Dentre as técnicas industriais utilizadas há o processo conhecido como “Oxidação Negra” que é realizado em baixas temperaturas, com imersão do aço da peça em óleo quente, ou banho de sal especial, ou mesmo a frio (soluções especiais). Outros processos utilizam fornos industriais com atmosfera de ar para aquecer a liga ferrosa até temperaturas da ordem de 500ºC e acrescentar (“pingar”) água como fonte de oxigênio. E em outros, aplicação ceras hidrocarbonetadas e ácidos inorgânicos e posterior oxidação [1] com aquecimento a temperaturas da ordem de 500ºC. Nesses processos, o objetivo é formar uma camada de óxidos tipos Magnetita e Hematita cujas características de menor coeficiente de atrito e determinadas propriedades físicas e químicas serviriam de barreira à interação química com outros metais em contato. A camada de óxido obtida nas condições descritas acima é bastante útil para determinadas aplicações industriais, tais como moldes de injeção de alumínio. Esse texto descreve o processo de oxidação desenvolvido utilizando a tecnologia de plasma.

Jul 30, 2018

By Steve Dillingham

Change occurs all of the time. In fact, it’s fair to say that change is a constant. Sometimes the change is inconsequential, but sometimes the change impacts us d i rectly and severely. Take regulations, for instance. Complying with regulatory requirements is just part of the job for those involved with explosives. But in recent years, it seems as if new or revised regulations in areas such as hazardous materials training, drug and alcohol testing, security issues, or local licensing/permitting standards are changing the way we operate on a recurring basis. Simply keeping track of all of these regulations has become a full-time job.

Jan 1, 2003

By J. C. Franklin

The Bureau of Mines substantially reduced shale degradation in a coal mine by two spray coat applications of a water-base epoxy sealant. More than 12,700 square feet of passageways were treated, and in 18 months only one failure occurred. This failure was due to improper spray application, Material costs averaged 13 cents per square foot, and labor costs were 7 cents per square foot. Labor included moving all materials into the mine, the setup time for each of the areas coated, and application of coatings.

Jan 1, 1977

By Steve Dillingham

There are some blasters and blasting companies that just seem to have better safety reputations than others. This is in spite of the fact that they are essentially doing the same type of work under similar conditions. To achieve that enviable safety reputation, it simply comes down to a strong safety culture prompted by a responsibility for others, as well as yourself and your company.

Jan 1, 2003

By W. D. Johnston, T. P. Thayer

THE minerals that collectively are known as chromite form an isomorphous series of the general formula (Mg,Fe) 0. (Cr,Al,Fe) 203. So wide is the range in chemical composition in this group that chrome ore consisting entirely of the mineral chromite may range from less than 30 pct to more than 60 pct Cr203. The most comprehensive published data on the chemical com- position of chromite are by Stevens,62 who made complete analyses of 52 samples of chromite concentrate from many localities in North, Cen- [ ] tral, and South America. These samples were mechanically purified to remove associated silicates and might be regarded as the cleanest chromite that could be obtained by any mechanical milling process. Fig 1 shows the predominant zone of isomorphism, within the triangular prism of composition defined by the mineralogical end members of the series, wherein his analyzed samples fell.

Jan 1, 1949

By J. W. Mills

In 1956 the discovery of nickel on Jumbo Mountain, Snohomish County, Washington, focused attention on this part of the Cascade Range, far more renowned for its timber than for its mineral resources. Hand specimens assaying as high as 13 pct Ni encouraged Discovery Mines Inc. of Mount Vernon, Wash., to stake 12 claims in Township 31 North, Range 9 East of the Willamette Meridian. The property was leased to Climax Molybdenum Co. in January 1957. Trenching, sampling, and geologic studies were carried out during the late summer of 1957 when most of the snow had disappeared. Although the deposits are only about four miles south of the logging town of Darrington and about two miles. as the crow flies, southeast of the end of a good gravel road from that town, all camp supplies and equipment were air-dropped, owing to the extremely rugged nature of the terrain. GEOLOGY The rocks of Jumbo Mountain comprise a series of folded Tertiary sediments forming a belt one half to three quarters of a mile wide, trending northwest about parallel to the strike of the beds. This belt is sandwiched between two extensive in-trusives—gabbro on the northeast and quartz dio-rite on the southwest—and has been intruded by dikes of fresh and serpentinized dunite. Shear zones follow many of the dunite-sedimentary rock contacts, and in these the nickel mineralization is concentrated. A few transverse faults offset the sediments and ultrabasics. Sedimentary Rocks: Two kinds of quartzite make up the greater part of the sedimentary section. One is dark purplish gray, very fine-grained, and thin-bedded; the other is light gray to white, medium-grained, and well-bedded. Locally the light-colored quart lites contain grit and conglomerate horizons, rich in pebbles of white chert and very fine-grained quartzite. Intercalations of dark argillites near the summit of the mountain give many of the cliffs a striking banded appearance. Dark gray to black, aphanitic, thin-bedded argillites occur throughout the entire sedimentary belt. Beds vary from a few inches to a few tens of feet thick and some, near the summit, contain numerous fossile (willow?) leaves. Only the thicker beds were mapped. The sediments are quite fresh on the northeastern side of the belt and become more metamorphosed (hornfelsed) toward the southwestern side. Brown biotite is present in the metasediments in increasing amounts as the quartz diorite is approached. Near the intrusion, porphyroblasts of plagioclase, up to 1 in. across, testify to the soaking of sedimentary rocks by solutions emanating from the quartz diorite. Most of the sediments mapped lie along the southwestern limb of an anticline, the axis of which follows the crest of the mountain and plunges at a low angle to the northwest.

Jan 1, 1961

By J. W. Paul

This circular is one of a series of reports on coal mining methods and cost s which are being prepared by the U. S. Bureau of Mines for the purpose of making available to those interested in the industry a knowledge of the mining methods employed in mines where mechanical and hand loading is practiced and the cost data on the several operations pertaining to the removal of coal from the working faces and its transportation to the tipple for loading into railroad cars. The methods employed are influenced by the natural local conditions with respect to the thickness and character of the coal beds and the overlying strata, the means employed for roof support and its control, and the disadvantages incident to the development of mines in thin coal beds.

Jan 1, 1929

By E J. Hill, F Huang, A Otto

Geochemical data from drill core samples is used in mineral exploration to enable geologists to understand subsurface geology. However, it is challenging to analyse these data sets rigorously and consistently. Manual data interpretation relies on the knowledge and experience of logging geologists. When multiple geologists are involved, it is possible to introduce inconsistencies in logged lithology type and scale of logging (‘splitters’ versus ‘lumpers’). Machine learning (ML) is a powerful tool for analysing high dimensional data (ie data with many variables) and large data sets (ie data with many samples). However, ML methods applied to drill hole samples do not incorporate spatial information and this can result in high misclassification rates and small-scale ‘noisy’ results. We demonstrate the use of multiscale spatial analysis (wavelet tessellation) as a pre-ML step to analyse spatial information. This step helps reduce misclassification and filter out unwanted small-scale variation in the data. In an experiment, we used wavelet tessellation and supervised ML to predict litho-geochemical rock types from geochemistry data. The data set is from the Valhalla uranium deposit near Mount Isa, northern Queensland. First, geochemical knowledge and statistical analysis was used to select appropriate geochemical elements for litho-geochemical classification. Second, the elements were processed using multiscale spatial analysis. Third, we trained a Random Forest model with the data set and found that the model performs worse in predicting rare rock samples than common ones. We applied over-sampling and down-sampling methods in aim to overcome this issue. As a conclusion, the combination of multiscale spatial analysis (to define rock unit boundaries) and Random Forests (to classify rock units) is a good method for rapid and accurate analysis of drill hole geochemistry.

Mar 22, 2022

By Renan Oss Giacomelli

The adhesion of multifunctional coatings on soft substrates is of paramount importance in the tribological behavior of this important class of surface treatment. In particular, scratch and indentation tests have been extensively used in order to assess this property. In this paper, the adhesion of a-C:H diamond-like carbon films deposited on nitrided low carbon steel was evaluated by indentation and scratch tests. The coatings were produced by PECVD onto 1020 steel substrates with two different surface finishing: ground (Sq = 0.184 µm) and polished (Sq = 0.002 µm). Indentation tests using a Rockwell diamond indenter were conducted and the adhesion evaluated by measuring the spalling region on images obtained by using optical microscopy. The analysis of the spalling regions produced semi-quantitative results, eliminating the subjective qualitative analysis proposed by the standard method VDI 3198. In addition, scratch tests were performed using the same indenter and a comparison between the two techniques was established.

Jul 31, 2018

By James R. McVey

A new method for measuring deformations of rock surfaces in underground excavations has been suggested by Dr. James Powell of Brookhaven National Laboratories (BNL) and subsequently developed and successfully demonstrated in a mining environment by the Federal Bureau of Mines, Spokane Mining Research Center (SMRC) and Brookhaven National Laboratories. The system uses 35-mm photography of targets strategically located on surfaces of interest, such as across the roof and on the sides of a mine drift or tunnel. The optimum tar-get, as determined in this investigation, consists of a white ?X? made with 1/8-inch-wide reflective tape on a black 6-inch square. Photographs, taken in pairs from two separated camera positions and at regular time intervals, were analyzed at the Bureau by hand and at Brookhaven National Laboratories using techniques and equipment similar to those used in cloud chamber film analysis. Test results show that deformation-measurement accuracies of better than ±0.020 inch in a drift that is 20 feet wide can be expected. This degree of accuracy, plus providing displacement data in the X, Y, and Z directions (rather than the one direction formerly possible), makes this a noteworthy and useful tool for industry as well as for mining research.

Jan 1, 1974

By Baki Özüm

Early evaluations of Pasquia Hills kerogen shale deposits by Geological Survey of Canada, Saskatchewan Geological Survey, Manitoba Energy and Mines and Sun Oil Company, using modified Fischer Assay, Rock-Eval and other techniques, estimated recoverable reserves of about 2.6x109 barrels of oil in areas favorable for strip-mining; each metric ton of ore was determined to yield about 30 L to 50 L of shale oil remarkably high in aromatic compounds. Western Petrochemical Corp. (WPC) is holding two Oil Shale Exploration Permits covering about 76,635 hectares in the Pasquia Hills Region of eastern Saskatchewan and conducting a 15-corehole drilling program to determine stratigraphic correlation on both first and second white specks kerogen shale. In this program, correlation will be established between oil yield and oil quality, using different retort techniques, including modified Fischer Assay, steam retort and Rock-Eval. Results will lead to further resource evaluation and to a preliminary engineering design for a shale processing plant, including selection of retort process, upgrading of shale oil to petrochemical feedstock, hydrogen management, energy balance and evaluation of environmental impact.

May 1, 2002

By Robert R. Beebe

At first glance, mineral processing on an industrial scale might seem entirely in the realm of macro-engineering, with large machines operating on minerals and rocks to achieve size reduction, classification, chemical treatment, separation and dewatering. These operations must be conducted on a large scale to be of practical interest. But the machines and processes may not be designed and operated to take fullest advantage of micro-engineering factors. At the same time, idealized designs based solely on micro-engineering research may require adjustments to gain the desired results in the larger scale, operational context. Using micro-engineering research in this way allows the design and implementation of more efficient versions of the machines and processes currently used, while aiding the revolutionary developments unlikely to come from macro-engineered, trial-and-error solutions. Thus, from an industrial viewpoint, micro- and macro-engineering are complementary functions.

Jan 1, 1992

By Stephen P. Signer, John L. Lewis

This paper presents the results of a case study conducted in a two-entry gateroad in a coal mine where excessive roof deformation and bolt loading resulted in failure of many roof supports. The instruments consisted of 16 fully grouted, strain-gaged resin bolts, load cells on both full and partially grouted cable bolts, and vertical deflection multipoint extensometers. These instruments were installed on-cycle to measure loading on bolts in an existing support pattern and to determine if cable bolts could be used to improve roof stability. Results showed significant amounts of movement within the bolted zone. In some cases, these movements were enough to load the supports past their ultimate strength. Geology appeared to be a significant factor in localized roof degradation; that is, a very weak rock layer in the immediate roof overlain by a very strong rock layer contributed to the development of shear planes. Only one instrumented bolt had a maximum strain of less than 2,000 microstrain, which was the yield point of the steel. The average maximum strain on all bolts was 20,000 microstrain. However, electrical continuity to many gages was lost and a pattern was noted that would indicate possible bolt failure. Wire mesh and concrete cans installed as secondary support performed very effectively.

By Guy Ervin, Delwin D. Blue, John E. Conley

"INTRODUCTION Extraction of alumina from various materials, such as low-grade bauxite and clay, by means of a lime-soda sinter has been the subject of a number ofinvestigations (1, 2, 3, 4, 5, 7, 9, 10, 11, 12, 13, 16, 17). 5/ in recent years, Although many of the details of these investigations are lacking, it is believed that there is one difficultly that frequently develops under certain conditions, namely, that of thickening or gelation of the slurry formed during extraction of the sinter. If gelation occurs even to a slight extent* Serious mechanical difficulties result, very low liquor recoveries are obtained, and the extraction step becomes virlually inoperable. Under 'favorable conditions, a solid gel is formed which can only be removed from the equipment with great difficulty. At the Eastern Experiment. Station of the Bureau of Mines in College Park, Md., a study of lime-soda processes was begun in November 1941. This work has included studies on low-grade bauxites, kaolin clay, and nodular diasporic clay. Gelation was most serous with kaolin clay and least with diasporic clay. As a part of the Bureau's investigation, a study was made of the effect of the pertinent variables on gelation. The results permit the selection of various sets of conditions at which gelation will not occur. These data are essential to the final selection of optimum conditions for the over-all process."

Aug 1, 1946