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By D. A. Fenton

Two large 34 ½ foot diameter mills have seen seven years of continuous operation before massive fracturing occurred on one of the trunnion cones. These fractures were discovered when liner changes were made. Four modes of failure were identified, three of the modes combining to cause a large circumferential tear in the 4-inch cone plate. A theoretical account is made of the modes of fracture and comparison made with field results. New material was used to repair the fractured cone, and the complete repair took ten weeks. The repair was monitored and lasted twenty-six weeks before the newly designed structure was available.

Jan 1, 1982

By V. Rajaram

The oil shales located in the Appalachian Basin cover an eight-state area of the eastern U. S., and are referred to as Devonian (black) shales. These shales have been exploited for their gas potential for several years. The Institute of Gas Technology (IGT) has conducted research since 1972 on the production of shale oil from the Devonian shales, and this resulted in the development of the HYTORT process. This process demonstrated that the yield from the Eastern oil shales can be greater than the value indicated by the Fischer assay method. IGT estimates that 423 billion barrels (67.3 x 109 m3) of oil could be recoverd by HYTORT processing of surface-minable eastern U. S. shales. Recently American Syncrude Corporation and Southern Pacific Petroleum N. L. have proposed oil shale projects in Kentucky. This paper will describe the surface mining and retorting techniques that have been studied for exploitation of the Devonian shales, and enumerate the problems that have to be overcome before commercial production can be realized from these shales.

Jan 1, 1983

By William A. Riggs

Salt, a non-metallic mineral whose use dates back to earliest history of mankind, and whose uses cover the widest range for any mineral raw material, is generally of widespread occurrence in commercially recoverable quantities in the oceans, in certain sedimentary rocks, in certain lakes, and in certain underground waters. Passing over geological detail, it may be said that, generally, all of the salt in the world has, at least once in geological history, been in solution in the oceans. The total salt content of today's oceans, said to equal 4.5 million cubic miles of rock salt, dwarfs the tremendous volume of salt in the sedimentary rocks. In 1958, United States production of salt was about 22 million net tons and world production about 82 million. About 3 percent of United States production is table salt, with chemical, municipal, industrial and agricultural uses taking the remainder. Mississippi River. Figure 1 has been expanded sufficiently to show also those salt occurrences and producing points which might economically ship salt into these states. Although widespread in occurrence, salt deposits and possible production areas generally show very sharp local boundaries. Salt-for non-table use is susceptible to ?place value?, a common problem in low valued raw materials, where transportation costs often exceed the value of the material f.o.b. the production point. Generally only large capacity mechanized salt producing operations can compete in United States markets, as contrasted to the many small local salt evaporators in less industrialized Mexico.

Jan 1, 1962

By M. S. Tsai

Recovery of uranium from wet-process phosphoric acid is a newly developed source of uranium. Many processes have been developed but the OPAP (octylphenyl acid phosphate) process is still the valuable one because the OPAP reagent compound has the high extraction ,power and cheap cost. The OPAP process was already studied by murthy(1) in 1970 and its complete process flow sheet was first fulfilled by F.T. Hurst(2) in 1974. WCFC(3) (western Co-op Fertilizer Ltd.) in cooperation with ESI (Earth Science Inc.) set up the OPAP uranium recovery pilot plant in Canada in 1978. We have studied the OPAP process since 1974 and first improved the OPAP extractant by proper adjustment of the DOPAP/MOPAP mole ratio with CH3OH-H20 method, resulting in shortening the phase separation time and avoiding the precipitation occurrence in our process. Second, we utilize the reduction and oxidation occurring by DC power supply on either side of the membrane to achieve the extraction and stripping at the same time. An improved OPAP process in which high recovery yield of uranium and acid uncontaminated by iron has been developed in our laboratory.

Jan 1, 1982

By David L. Giles

The alkalic igneous province of Montana consists of centers of laccolithic and stock-like intrusive complexes with associated sills, dikes, and breccia pipes (e.g., Judith, Highwood, Little Belt Mts.); isolated plug-like mafic bodies (e.g., Smokey and Eagle Buttes); and clusters of kimberlitic diatremes and ultrabasic dike swarms (Missouri River Breaks). The province extends in a belt throughout central Montana from the North Absaroka Range in the south to the Sweetgrass Hills on the Canadian border. Intrusive activity ranged in age from Late Cretaceous to late Miocene, peaking at about 50 m.y, ago. Diverse types of significant epithermal gold mineralization occur at many of the laccolithic centers. This mineralization took place in large part during the waning stages of, or following, igneous activity. Large remnant travertine blankets in the region attest to comparatively recent hydrothermal activity. The quartz-pyrite-gold mineralization ranges from igneous- hosted stockworks or fracture sets (Zortman-Landusky and Neihart districts) and breccia pipes (North Moccasin Mts.) to replacement zones in flanking and upwarped Madison Group limestone (Gilt Edge and Kendall districts). The latter are mostly localized by intraformational solution breccias in the upper Madison, notably near porphyry contacts. Gold mineralization in the province was accompanied by varying amounts of silver, base metals, sulfosalts, and tellurides, with quartz, fluorite, carbonate, and barite and gangue. Gold occurs as auriferous pyrite, sylvanite, or in native form. Since the 1880's, primary gold production from numerous scattered deposits in the Judith, Moccasin, and Little Rocky Mountains, along with byproduct gold from the Neihart silver district (Little Belt Mountain), has totalled around 2 million oz. The major deposits were in the 1-2 million ton range at an average gold tenor of 0.3-0.6 oz per ton. Most of the ore was mixed oxide or carbonaceous sulfide ore and was treated either by amalgamation or by roasting-cyanidation. Current activity includes heap-leach operations on bulk- tonnage low-grade (approximately 0.03 oz per ton) ores at Zortman-Landusky, and several small-scale, experimental leach or mining operations on carbonaceous replacement ores, as in the Kendall district and Spotted Horse mine. Current exploration efforts for gold are focused not only in the old established districts, but also in and around other alkalic centers, which have been unproductive to date, such as the Crazy Mountains, Sweetgrass Hills, and Bearpaw Mountains. Target concepts in these efforts are porphyry-hosted stockwork or disseminated gold ores and Carlin-type replacement lodes in the flanking Madison or other favorable carbonate units.

Jan 1, 2013

By XUEWEN WANG, Changda Zhang, Huaguang Wang, Mingyu Wang, Bin Hu

The copper smelting process produces plenty of copper slag every year, which is a hazardous solid waste, but a secondary resource. In the present study, the extraction of copper, nickel, and cobalt from copper slag was investigated through the process of sulfation roasting–water leaching and the process of sulfation roasting–sulfate decomposition roasting–water leaching respectively. Compared with the process of sulfation roasting–water leaching, the process of sulfation roasting–sulfate decomposition roasting–water leaching is a better choice, which could not only get almost the same leaching of copper, nickel, and cobalt as the former process, but has a lower leaching of iron and aluminum. For the process of sulfation roasting–sulfate decomposition roasting–water leaching, the leaching of Cu, Ni, and Co reached up to 74.2%, 71.1%, and 69.6% respectively, under the optimal conditions including sulfation roasted with 80 wt% sulfuric acid addition at 200 °C for 60 min and sulfate decomposition roasted at 650 °C for 60 min, followed by water leached at 90 °C for 30min with a liquid–solid ratio of 2 ml/g. The leaching of Fe and Al was only 4.9% and 17.6%.

May 4, 2020

By W. C. Dailey

The Groveland Mine. Concentrator and Pellet Plant are located in Dickinson County in the Upper Peninsula of Michigan. The construction of the Groveland Mine in 1959 was the first United States operation for the Hanna Mining Company in mining and beneficiating low grade iron formations. (1) The plant produced concentrates at 675,000 lt/yr. (746,600 mt/yr.) which was used as sinter feed in the steel industry from 1959 to 1963. Upon completion of a pelletizing plant in April, 1963 production increased to 1.6 million lt/yr (1.77 million mt/yr) of pellets. After the plant expansion, mill capacity increased to 2.2 million 1t/yr (2.43 million mt/yr.), producing 2.0 million It/yr (2.23. million mt/yr.) of pellets assaying 63.0% iron and 7.0% silica. (1) Prior to April, 1971 the concentrator operated with a flowsheet consisting of spirals and a petroleum sultonate iron notation circuit. This was presented in a paper by R. R. Smith and E. E. Sougstad, "Flotation at the Groveland Mine" in the 50th Anniversary Volume entitled "Froth Flotation". The ore body at the Groveland Mine consists basically of two types of iron formation (34% total iron, 20% magnetic iron head), the most abundant of which is a bedded magnetite-chert-silicate rock. This is intermingled to varying degrees with non-bedded to poorly bedded hematite-clastic quartz-chert rock. (1) In developing the Groveland flowsheet, Humphrey spirals were used because of their ability to produce a coarse size concentrate at a low cost. Tests run in the lab and pilot plant on the Groveland ore showed a. spiral weight recovery in the 27 to 33% range. (2) However as the ore body was opened up, it became evident that the most abundant ore type did not liberate at the coarse size fraction needed for spirals. Plant recoveries for the first five years operating the spirals only averaged from 10 to 15% weight recovery. In 1971 the weight recovery on the spirals had dropped to a low of 5%. To increase iron recovery and at the same time increase plant capacity with the least effect on the present operations the mill flaw-sheet proceeded from a spiral-notation circuit to an all flotation circuit to a magnetic separator-flotation circuit. During this changeover the concentrate grade also had to be improved to meet market demands. To do this the following changes evolved

Jan 1, 1978

By W. N. Hamilton

British Columbia is geologically favourable for a rich variety of industrial mineral occurrences. Some have been produced for years, others overlooked until recently. Major production occurs for asbestos, gypsum, limestone, magnesite, silica and sulfur; lesser production for a dozen others. For several of the minerals, potential is much greater than existing production. New production opportunities exist also for diamonds, niobium and REE minerals, fluorspar, kyanite, nepheline syenite, talc, and several others. Alberta, though geologically less diverse, also has many industrial minerals. Limestone, salt and sulfur have the major production; clay and shale, silica, sodium sulfate and a few others lesser production. Opportunities exist for expanded production, and for new production in heavy (Ti -Zr) minerals, formation brines (Ca-Mg-I-Li), and gypsum.

Jan 1, 1987

By Calvin L. Stevenson

The probability of a particle passing through a maze is predictable and consistent. This principle may be utilized to effect a particle size separation of materials by presenting a physical maze to a stream of material that will allow the fine particles to pass, while deflecting the coarse particles. A maze is effective even though all apertures encountered are many times larger than the particles being separated. By designing a machine that allows the probability parameters to be controlled and varied without changing physical dimensions, probability sizing becomes a useful tool for the separation of granular materials.

Jan 1, 1967

"The 34th International Conference on Ground Control in Mining (ICGCM) was held July 28–30 at the Lakeview Golf Resort and Spa in Morgantown, WV. Ground control experts have gathered at this location since 1981 to share ideas and successes for improving designs and technologies to enhance the stability of surface and underground mining operations. Ground control is important to all mining operations but is particularly crucial to underground mining to ensure miner safety and operational viability.The year’s event had 240 registered attendees with 20 pecent of that attendance being from the mining industry. A remarkable number of industry representatives attended given the challenges currently faced by the mining industry. A true testament to the value of the conference, the performance of Tom Barczak and Steve Tadolini as co-chairs and the drawing power of the many exceptional speakers that have attended the annual event for many years.The conference operates under the direction of a board of directors with the cooperation, wisdom and assistance of a large organizing committee. Visit the conference website, www.icgcm.conferenceacademy.com, to view the membership of the board and the committee and to access previously published papers."

Jan 1, 2015

By Robert W. Row

The run-of-mine coals in the U.S. being fed to coal cleaning plants have become increasingly finer due to the adoption of modern, mechanized mining methods, and economics are dictating that finer fractions, as well as the coarser fractions, be cleaned. Traditional dewatering methods (vacuum disc filters and centrifuges) are proving inadequate for preparing fine refuse for disposal or fine coal product for downstream handling. The Electric Power Research Institute has been supporting research into the nature and limitations of mechanical dewatering, and novel ways of improving it. The efficiency of various silicone-based chemicals at aiding dewatering was investigated, and it was shown that the final moisture content of hydrophilic coals after vacuum Filtration could be reduced by 1 to 5% with up to 40% increase in filtration rate by addition of one of several of these silicones. EPRI also has an on-going program at its Coal Cleaning Test Facility to investigate the performance of the Larox pressure filter in comparison with that of the disc filter and solid bowl centrifuge. While improvements to the dewatering performance currently being obtained in existing operating plants by such means are achieveable, a fundamental study has shown that, regardless of changes in operating conditions, there may be a limit to the lowest cake moisture content attainable by mechanical dewatering of a given sample of coal fines. Determination of this limit for a specific coal would be useful in designing facilities to dry and handle it.

Jan 1, 1984

By S. D. Irons

With the passage of recent national and state legislation aimed at tighter regulation of air pollution and smoke control, attention has been focused on a problem which has long confronted the coal industry--the disposal of coal waste with its inadvertent ignition. Even as recent as 1935, a decision from the Allegheny County Court of Common Pleas confirms the stand taken on control of burning coal refuse disposal areas. "The uncontroverted testimony is that there is no feasible method of operating a coal mine without a gob pile on the surface, as no use has ever been found for this troublesome by-product of mining; that every large coal mine has a large gob pile close to its tipple; that sooner or later these piles all ignite through spontaneous combustion; that practically every large mine in Western Pennsylvania has a burning gob pile, and that there is no known means of averting such a fire." 19* As a result of the past "no regulation policy," there are presently on the order of 500 burning refuse banks, of which 213, 142, and 49 are found in West Virginia, Pennsylvania, and Kentucky, respective¬ly. 18 Many of these refuse banks have burned for 40 years or more; many others may continue burning for a like period. It is estimated that the annual emission from these smoldering piles approaches 183,000 tons of pollutents which may produce many deleterious effects on the populace, property and vegetation in the proximity to the sources.16 To date, little progress has been made in alleviating the pollution from the currently burning refuse banks; however, numerous investigators who are researching the causes of ignition, as well as preventative disposal techniques (refuse compaction, layering and crushing to finer sizes) have met with some success in handling the newly discarded coal refuse.

Jan 1, 1967

By Donald M. Benjamin

Florida's electrical needs are served by 58 utilities of practically every type: six investor-owned, 34 municipal, 17 cooperative, and one federally-owned. They range in size from a small municipal system with a, 2 MW annual peak demand CD a large investor-owned utility serving about one-half of the state with an annual peak demand of 8,600 MW. (1),(2) These utilities are interconnected at several voltage levels with 230kV serving as the pre-dominant voltage for the bulk power transmission system. About 275 miles of 500kV circuits are found within two systems, but no tie-lines yet exist at this voltage. Due to Peninsular Florida's (that portion of the state east of the Apalachacola River) geographic location and shape, it cannot, at present, depend upon its interties with the remainder of the nation to completely support the sudden loss of the state's largest generator. Therefore, the utilities maintain a total amount of spinning reserve to cover for this single contingency outage at all times. Most of the state's electric utilities belong to the Florida Electric Power Coordinating Group (FCG) which, through its standing committees, coordinates the planning and operation of the member systems. Though a formal, centrally dispatched pool does not exist in the state, generating utilities which belong to the FCG's Operating Committee subscribe to an energy broker operation to maximize the savings that can accrue from economy interchange. Studies are underway, with participation from the staff of the Florida Public Service Commission, that are investigating both central planning and dispatch of the peninsula's electric utilities. Florida's electric load is mainly residential. During: 1976, 48.8% of all electrical energy use was by residential customers; 31.8%, commercial; 16.2%, industrial; and 3.2% for all other. By comparison, 32.7% of the United States' load was residential, followed by 40.5% industrial, 23.0% commercial, and 3.8% other.

Jan 1, 1978

By P. A. C. De Ruiter

The Lower Cretaceous salt deposits of the Gabon Basin and Congo Basin were said down on ton of an Burly Cretaceous Lato Jurassic, continental graben fill that represent!) the rifting phase of the Afro-American continent. The salt 13 characterized by high percentages of potash and magnesium salts and the scarcity of sulphates and carbonates. The salt probably originated from a brine that was already enriched in high-soluble salts before entering the Gabon Congo basins. Their low-solubility equivalents are found in the Cuanza Basin of Angola. Commercial mining of the potash salt is only possible in those onshore areas where it is essentially undisturbed, shallow and of the right chemical composition. These conditions are net in Congo where the Holle mine produces from rich sylvinite deposits.

Jan 1, 1978

By M. Sinirkaya

The dissolution process of phosphate rock from the Semikan area (Mardin-Mazidagi, Turkey) using dilute phosphoric acid has been investigated. The work involved studying the effect of important variables, such as reaction time, stirring speed, particle size fraction, phosphoric acid concentration and temperature. Van der Sluis et al.?s model was used to determine the rate of the partial dissolution of phosphate ore. Mass-transfer coefficients (kL) varied between 2.8 and 28.5.10-3 m.s-1. The activation energy of the process varied between 16 and 20 kJ.mol-1. It has been found that the dissolution process is controlled by calcium ion diffusion, rather than by chemical reaction.

Jan 1, 2010

By Jr. Freed

Basic design features, details of the face ventilation system, roof support and Operator protection system, certified lighting, and in-mine evaluation plans are presented for an Automated Extraction System (AES) that has been designed to fill needs which are present in the Mining Industry. The philosophy of design and proposed operation of the machine, as well as the relationships between these factors, are reviewed. The AES is designed to help overcome production problems resulting from the regulation of roof control, clean-up, ventilation, dust suppression, and operator protection required by the Federal Coal Mine Health and Safety Act of 1969. The design permits more continuous operation and greatly improves operator safety. The machine is a full-face drum-type continuous miner which includes self-advancing, continuous temporary roof support and permanent roof support equipment. Onboard self-advancing face ventilation, dust suppression, and air scrubbing equipment are also included in the design. A further improvement over existing equipment is the incorporation of an automatic programmed cutting cycle control system. All mining functions including movements of the roof support system are handled by this automatic system.

Jan 1, 1978

By A. A. Terchick

It has been reported in the literature that there is a substantial economic incentive for removing sulfur from coal. Therefore, U. s. Steel initiated an investigation to determine the feasibility of lowering the sulfur content of its Pittsburgh-seam coal. Preliminary crushing and washability studies on a representa-tive sample indicated that substantial sulfur reductions could be attained. Figure 1 shows the effect of the top size of a given coal sample on the sulfur content of the float-l.45 specific-gravity fraction of coal. At a top size of 3 inches, the raw-coal sulfur content of 2.32 percent was reduced to 1.64 percent. Crushing to a top size of 20 mesh reduced the raw-coal sulfur to 1.25 percent. Below a top size of one inch, the sulfur content decreased rapidly as top size was decreased. Figure 2 shows the effect of specific gravity of separation on pyritic sulfur. Normally this coal has an organic-sulfur content of approximately 1 percent. As expected, pyritic sulfur was reduced as the separating gravity was lowered for all the various size fractions shown. The rate of decrease in pyritic sulfur was gradual above 1.45 specific gravity, but great below 1.45. Greater sulfur reductions were attained on the coarser sizes with decreasing

Jan 1, 1971

By Zhan-fang Cao, Hong Zhong, Li-feng Li, Shuai Wang, Xiao-yu Cao, Guang-yi Liu, Ming-ming Wang

"In recent years, there has been an increasing focus on the hydrometallurgical processing of molybdenite, with the decline of high-grade and easily handled molybdenum minerals. In this work, a novel method of selective extraction of complex molybdenite concentrate, which is characteristic of high-grade copper ore, has been investigated. The results show that the leaching of chalcopyrite was impacted by the pH of the electrolyte when sodium carbonate and ammonium acid carbonate were added to the electrolyte. The leaching rate of molybdenum reached 99.39%, but chalcopyrite could not be leached at all in 240 min under experimental conditions of liquid-to-solid ratio 25:1, concentration of NaCl 4 mol/L, pH=9, room temperature and agitation speed 400 rpm. The grade of copper in the residue was 21.84%, with a recovery 99.93%. The technology of selective electro-oxidation leaching of molybdenum and recovery of copper from complex molybdenite concentrate is an effective separation method. The diffusion control model can be used to describe the process of leaching of molybdenum. The activation energy of the leaching reaction was found to be approximately 9.21 kJ/mol.IntroductionWorldwide, high-grade and easy-to-handle ore is decreasing, while the proportion of low-grade and complex ore is increasing. Porphyry copper ores with associated low-grade molybdenite are very abundant in China. Molybdenum is a valuable byproduct in the processing of porphyry copper deposits where the molybdenum is present in low quantities in the form of molybdenite (MoS2). In the conventional processing of copper sulfide ores by froth flotation, most of the molybdenite in the ore floats along with the copper sulfides. In this way, a bulk copper-molybdenum concentrate is produced. Afterward, the bulk coppermolybdenum concentrate is treated by differential flotation to obtain a rougher molybdenum concentrate, which requires several successive cleaning steps to produce a final molybdenum concentrate. However, it is widely recognized that flotation alone cannot economically produce a high-grade molybdenite concentrate, i.e., with less than 0.5% Cu. Therefore, in most cases, it is necessary to use a final step of chemical purification of the molybdenite concentrate to reduce the copper content to a level suitable for the market (Antonijevic and Pacovic,1992; Gerhardt et al., 2001; Fu and Zhong, 2003; Reza et al., 2006, Rafael et al., 2013)."

Jan 1, 2015

By S. Mojeddifar, N. Ostadmahdi Aragh, M. Hemmati Chegeni

This work integrated selective principal component analysis (SPCA) with a singularity fractal model to map hydrothermal alterations of argillic, phyllic, and propylitic in the north-west of Kerman city in Iran. SPCA results were provided for short wave infrared (SWIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor tomap phyllic and propylitic alterations. Also, the bands 5–7 were applied to map the argillic alteration zone. SPCA results could present useful information for alteration mapping but it does not show the purest pixels of alteration. Therefore, a fractal model of singularity was applied to highlight the different alteration pixels in the Kerman Cenozoic magmatic arc (KCMA). Thus, the singularity index of different hydrothermal alteration zones was produced. Comparing the obtained results with the field data showed that Kader, Serenu,Meiduk, and Abdar deposits were acceptably identified by alteration mapping. Also, it seems that the singularity index could not discriminate the hydrothermal alterations of argillic and phyllic. The same spectral signature of kaolinite and muscovite minerals is the main reason for misclassifications.

Jul 20, 2020

By Yaxiong Wang, Yong Li, Yuedong Wu, Haigang Dong, Jiachun Zhao

A roasting-leaching process has been developed for concentrating platinum group metals (PGM) from a PGM-containing ferroalloy. The optimized roasting conditions used a NaOH-to-ferroalloy mass ratio of 1.2 at 600 °C for 2 h. The roasted product mainly comprised Na4SiO4, NaFeO2 and Fe2O3. The iron oxide and sodium silicate associated with the roasted product were leached in water and dilute sulfuric acid solution, while the PGM was concentrated in the acid-leached residue. A PGM concentration of 23.4% was obtained with assaying, and the concentration factor of PGM from the ferroalloy to PGM concentration was greater than 9.

Jun 14, 2021