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By Guangyao Si, Ismet Canbulat, Xun Luo, Yi Duan

Routine analyses of seismicity and event locations are essential for coal burst risk management, especially in the presence of unfavorable and complex geology. In an Australian longwall coal mine, a small-scale seismic monitoring network was installed to monitor a section of a major dyke intersected by the roadway, which was classified as a coal burst prone zone. The Deep Convolutional Neural Network (DCNN) technique was adopted for automatically discriminating seismic events to assess seismicity in this zone. The discriminated seismic events were located with the Shortest Path Method based on the Boundary Discretization Scheme (BDS-SPM) for temporal-spatial seismic event distribution analysis. The results demonstrate that the seismic events are discriminated with an average accuracy of 94%. Moreover, the seismic events are more accurately located using the BDS-SPM with a 3D heterogeneous velocity model compared with results obtained with a homogeneous velocity model. The temporal and spatial variances in seismic activities identify that the rock fractures in the dyke zone are closely related to the longwall mining process and a local dyke has a controlling influence on the stress concentration in its vicinity.

Apr 26, 2022

By E. A. Domínguez

La Espingarda kaolin deposit was formed by ?in situ? alteration of volcaniclastic rhyolitic rocks belonging to Jurassic Marifil Formation. Three volcanic lithofacies were identified: porphyric biotitic ignimbrites (PBI), a coarse lithic ignimbrite (ILG), a fluidal intrusive rhyolite (RFI), all kaolinized in different degrees. The alteration covers an ellipsoidal area of ~20,000 m2, with its alteration decreasing downwards and disappearing at 8-12 m from the surface. The length to thickness ratio of alteration is 60:1. An erratic silicification was found as small zones (<3 m2) of quartz stockwork. The mineralogy is kaolinite + quartz + feldspars + Fe-oxyhydroxides ± halloysite ± illite and interstratified I/S, although the relative proportions change in each rock type. Due to coarse grain size and high quartz content, natural kaolin is unsuitable for slip cast ceramics, unless beneficiated. Washed ILG kaolin has the best rheological properties and behavior in casting and drying for its mineralogy, particle size distribution, thin texture and surface activity, as well as a certain fusibility and firing kinetics. PBI and RFI kaolins, due to finer texture, smaller grain size, lower surface activity, and higher halloysite amount, have worse slip viscosity and thixotropy that are due also to soluble salts. For the same reason, they have good casting and drying properties, but their purity brings about higher softening temperatures and water absorption. Several parameters are used to discriminate between hypogene or supergene kaolinite genesis. The hydrothermal genesis is mainly sustained by fluid inclusion temperature (150-180ºC) in quartz veinlets, while weathering is supported by deposit morphology, simple mineralogy, kaolinite stable isotopes (d18O ? 18, 13; dD ? ?59; ?85) and paleoclimatic record. It is concluded that a weathering process formed the main alteration with some participation of steam-heated meteoric waters. Neither the contents of Au, Ag, As, Sb, Hg, nor drill data support the existence of any epithermal gold mineralization at the kaolinite bottom.

Jan 1, 2010

By James Charles McHardy

During 1980-2000, the Florida Phosphate industry will deplete its Central Florida Polk County reserves. As a result, new mines will be built in the ?so-called? Southern Florida Reserve areas. These new mines will require new mining, beneficiation and tailings disposal technologies in that the southern reserves have different characteristics than have been encountered in the Central Florida deposits furthermore, government regulations will necessitate the development of new tailings and clay disposal methods. This paper reviews these challenges for the phosphate industry and how these opportunities can be expected to effect plant design and plant operating practices.

Jan 1, 1981

By Dan S. Nilsson

When an open pit mine is deepened, more and more waste rock must normally be removed. Techniques for optimization of open pit design are well-established within the mining industry. The recommended method is to choose the open pit alternative with the highest net present capital value of open pit and future underground mining. When the open pit is mined out, the operation must be closed, or, if it is profitable, mining must start underground. When planning an underground operation we experience the same type of optimization problem that occurs when determining the optimal depth for open pit mining. When mining underground the ore body is often divided into a number of areas, blocks or slices, each containing a transportation system with trains, trucks, conveyors, etc. When all the ore within such a part of the deposit is extracted, the operation must be closed, or, if it is profitable, a new transportation must be developed. The question that now arises is: how large a pan of a deposit shall be included in the first development and how much shall be left for future consideration?

Jan 1, 1981

By R. Bhaskar

The objective of the project was to optimize the ventilation parameters of a continuous miner underboom scrubber to further control. the amount of airborne dust discharged during mining, to further reduce the exposure of face personnel for an exhaust brattice ventilation system, and avoid recirculation of contaminants at the face. This research was performed in an underground coal mine in Utah. The tasks included preliminary face ventilation evaluation and optimization of the scrubber system to eliminate recirculation of the scrubber discharge air. Airflow tests were conducted on the currently used dust control system and the modified scrubber system. Tracer gas tests were performed to evaluate face ventilation effectiveness. Confirmatory tests of the scrubber system under actual operating conditions, modifications to the scrubber system, and a comparative evaluation of the scrubber system vs. the existing system were performed. This paper presents the results of the airflow pattern tests and the respirable dust levels in the modified scrubber system and the existing system. The optimized face ventilation parameters and the developed operating guidelines may provide the benefits of dust reduction, better face ventilation, and improved visibility.

Jan 1, 1994

By R. W. Wittkopp

The Relief Canyon gold deposit is located approximately twenty- four kilometers east of the town of Lovelock in Northwestern Nevada. At Relief Canyon, the Late Triassic Grass Valley Formation has been thrust over the Late Triassic Natchez Pass Formation. The lower plate Natchez Pass Formation is composed of massive gray dolomitic limestone which is locally silty and sandy. The upper plate Grass Valley Formation is composed of shale, siltstone, argillite and quartzite. Gold mineralization at Relief Canyon occurs along the highly brecciated thrust contact between these two formations. Weak gold mineralization often occurs above the thrust in the Grass Valley Formation, however, most of the ore grade mineralization is present below the thrust in the brecciated Natchez Pass Formation or where the two formations are mixed as a result of movement along the thrust. Several types of gold mineralization have been recognized at Relief Canyon. A large amount of the ore is present as a jasperoid breccia, however, significant amounts of ore occur as a mixed breccia composed of upper plate rock, fresh limestone, clay and jasperoid breccia. Gold ore also occurs in a fresh limestone breccia which contains a large amount of clay. Below masses of jasperoid, jasperoid stringers containing gold extend into the fresh limestone. Gold mineralization at Relief Canyon appears to be truly disseminated and has the typically associated trace elements of arsenic, antimony, mercury and fluorine. The Relief Canyon deposit can be classified as a structurally controlled disseminated gold deposit. Other deposits that fit this classification are the Pinson and Dee gold mines.

Jan 1, 1984

By J. Wiebmer

The two most important influencers of cost-per-ton in an underground mining machine are its productivity (tons/hour) and its availability-utilization (hours/year). Operating cost and initial price have far less impact. This paper reviews a cost-per-ton sensitivity analysis for underground mining equipment and discusses benchmarks for measuring its performance. The conclusion is that miner-supplier partnerships and the Information Age are the two most significant trends in cost-per-ton reduction.

Jan 1, 1997

By J. J. Bean

The development drilling program of the Copper Cities mine indicated that the molybdenum content of the ore would be about 0.011% MoS2&apos; The molybdenum content of the Miami mine at the same time was about 0.025% MOS2&apos; The Miami mill had a very successful molybdenum operation which used bleeder turbine steam from the Miami power plant for the steaming operation. The much lower grade of the Copper Cities ore, the absence of a source of low cost steam and the use of sodium aerofloat as the copper collector which Miami experience indicated did not respono readily to the steaming technique made very doubtful the success of a similar operation at Copper Cities. However, the relatively few pounds of copper that could be recovered from the low grade Copper Cities heads made very desirable the recovery of the molybdenwa,as a source of additional revenue. Accordingly, shortly after the Copper Cities mill began operation, a research program was instituted to develop a suitable method of molybdenum recovery. This program explored first, the successful steaming process then in use at Miami and as expected, found it unable to decompose the sodium aerofloat copper collector. The known chemical depressants were then tried without much encouragement. Finally the copper concentrate was dried, not roasted, to 2-3% mOisture and this along with sodium ferro-cyanide and cyanide resulted in sufficient copper depression that a final molybdenum concentrate containing 1.0% CU could be made. The bench scale testing was followed by pilot plant testing. Sixteen

Jan 1, 1972

By Arnold Dix, Oliver Heger, Bernhard Kohl

In the USA, risk-based decision making has not been a common approach to tunnel safety in the past, but this is changing, as concepts such as “equivalency” in the NFPA 502 framework gain acceptance in the USA and elsewhere. In other regions, in particular in Europe, risk assessment techniques have been used for nearly two decades in many jurisdictions as an additional tool to complement the application of prescriptive guidelines and support decisions related to tunnel safety. After some initial difculties these methods are meanwhile a well-established element of tunnel safety management. There are several tools available which have been practically applied and further developed over years, such as the Austrian tunnel risk model TuRisMo, or the PIARC owned DG-QRAM model. Whereas TuRisMo is a holistic, system-based model, which is best suited to quantify and assess re risk and associated mitigation measures, DG-QRAM focusses on the risks related to the transport of hazardous materials. Depending on the objectives and the scope of the investigation and the regulatory environment tunnel risk assessment tools are in use for different purposes, mainly to demonstrate a sufcient level of safety and to decide on and select additional risk mitigation measures. The international eperience substantiates that the general approach is eible and that the methods and tools are mature and can be applied for different problems in different environments. First case studies like the risk study on conditions and permissibility of the transport of hazardous materials through the Eisenhower-Johnson-Memorial Tunnel in Colorado demonstrate the applicability of a risk-based concept for decision making in the US-American environment.

Jun 23, 2024

By B. Li

"Sepiolite is a magnesium-rich, porous, and fibrous clay mineral with broad applications. These applications take advantage of sepiolite’s high specific surface area and unique nano-sized channel structure. Over the past years, numerous materials and techniques based on the structure and property of sepiolite have been developed. This article reviewed the recent achievements in developments and applications of sepiolite in environmental protection, catalysis area, and nanocomposites. The prospectives of sepiolite applications is also discussed. INTRODUCTION Sepiolite is a magnesium-rich, porous, and fibrous clay mineral. The typical chemical formula of sepiolite is Si12Mg8O30[OH]4[OH2]4·8H2O [1]. Sepiolite has a high specific surface area and nano-sized channels because of its special structure [2]. This unusual crystal structure projected onto the [001] plane is shown in Fig.1 [3]. As it can be seen, silicon and oxygen atoms make up for the tetrahedral structure and magnesium and oxygen atoms form octahedral structure, respectively. Those tetrahedral-octahedral-tetrahedral ribbons expand boundlessly in one direction, leading to the special fibrous structure of the sepiolite. Every tetrahedral-octahedral-tetrahedral ribbon is combined to the next by an inverted Si–O–Si bond, which causes an interlaced layer with a continuous tetrahedral sheet and a discontinuous octahedral sheet. Terminal MgO at the edges of the ribbons is coordinated with two structural water molecules, which can form hydrogen bonds with zeolitic water molecules that are located in the channels running parallel to the fiber axis [3,4]. The Mg2+ ions inside the channels can be exchanged with other cations in solution. Therefore, sepiolite can be used to remove metal cations from aqueous solutions [5,6].It can be seen from Figure. 1 and Table 1 [7], the unique structure endows sepiolite with a substantial surface area and nanoscale channels. Its specific surface area reaches 320 m2/g and channel dimensions up to 3.7×10.6 Å. There are three active adsorption sites on the surface of sepiolite: one is oxygen atoms of the Si-O tetrahedron. The second is the structural water molecules paired with magnesium ions at the edges of the ribbons, which can form hydrogen bond with adsorbent. The last one is the Si-OH groups due to the breaks of the Si-O-Si bonds on the surface of Si-O tetrahedron. Thus, sepiolite has strong adsorption ability which has been widely used in environmental protection. Moreover, sepiolite has many significant features such as good mechanical and thermal stability, rheological property, porous, and easily modification, making it be a hotspot in chemical and biological researches. However, with the development of technology, broader and more advanced applications of sepiolite have been carried out in recent years. In this study, the recent achievement in sepiolite applications is summarized, the further tendency is also discussed."

Jan 1, 2018

By Ross W. Whipple

Applying geophysical techniques in potential geothermal areas has received: little attention in the United States, though it is widely used and accepted in New Zealand and Italy. In those countries it has been demonstrated that geophysical surveys can be useful in locating new geothermal areas and in directing test drilling programs. Geophysical studies in a thermal region can provide structural information and, if conditions are right directly; locate subsurface hot waters. They can give indications of sub-alluvial rock types and of the thickness of alluvial cover. In certain cases they can be used to estimate the power potential of a hydrothermal system.

Jan 1, 1963

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By J. K. Grunig

A process consisting of leach, continuous countercurrent decantation, resin-in-column ion exchange, evaporative crystallization of beryllium sulfate, and decomposition of the sulfate was developed for Spor Mountain, Utah, ores. The process is metallurgically sound, has a minimum of process steps, and is applicable to a wide variety of beryllium ores. The most novel aspect of the process is a resin system of ion exchange which is highly selective for beryllium and which rejects substantially all impurities except for minor amounts of aluminum, magnesium, fluorine, and sulfate in addition to beryllium. The oxide from sulfate decomposition meets specifications of potential users.

Jan 1, 1982

By Jameel Menashi

A process has been developed for recovering the refractory metal values contained in mixed secondary source materials such as contaminated grinding wastes, oxides and sludges. The wastes are calcined with sodium carbonate in air to convert the refractory metals to water soluble Na2CrO4, Na3V04, Na2Mo04 and Na2W04. The base metals, Fe, Ni, Co and Cu, are converted to water insoluble oxides. An aqueous leach of the calcine effectively separates the refractory metals from the insoluble base metals. Co, Ni and Cu can be recovered from the oxidic residue by conventional processing methods. The leach solution is purified and then treated to recover the refractory metals as Cr203, NH4VO3, (NH4)6Mo7024?4H2O and H2WO4. The purity of the products is sufficient for their use in many metallurgical applications. The Na+ values in the leach solution are recovered as Na2CO3(or NaHC03) and are recycled to the calcination step. It is shown that the process can accommodate a wide range of feed compositions and generates a minimum of aqueous effluents.

Jan 1, 1984

By Wayne W. Murdy

Since 1993, Newmont has been actively growing through the development of three major foreign mining operations with a fourth under construction. The first project, Yanacocha in Peru began operating in October 1993 at a time when political and business risk in that country was considered high. In 1995, Newmont began operating the Muruntau Joint Venture in Uzbekistan, the first of its kind in the CIS. In early 1996, Newmont started operating the Minahasa mine in Indonesia. Now, in early 1997, Newmont is undertaking the construction of a $1.9 billion project in Indonesia and is completing a feasibility study with our partner for the development of a gold operation in Mexico. All of these projects have been considered "risky" by most standards, and Newmont has been very successful in all of them through risk mitigation programs including utilizing strong and successful in-country partners, concentrating on developing a strong national workforce with minimal expatriate employees, utilizing World Bank, EBRD and IFC financing and building and maintaining strong ties with host governments. This paper describes in more detail, some of the risk mitigation programs that Newmont has used to successfully grow the company through development of major foreign mining operations.

Jan 1, 1997

By P. L. Dunn

Automatic control of fine coal cleaning circuits has traditionally been limited by a lack of sensors. Although several nuclear-based analyzers are available, none have seen widespread acceptance. In this investigation, image analysis is used for on-line determination of ash content in fine coal slurries. The ash content of a flotation tailings stream is correlated to the mean gray level of the slurry. Based on a 90% prediction interval, an analysis of sensor performance indicates an accuracy of 73 ± 4% ash over a range from 65-90% ash. While this result is comparable to existing nuclear-based analyzers, the video-based system is only a fraction of the cost. The sensor is currently installed at the Middle Fork preparation plant owned by Pittston Coal Company.

Jan 1, 1997

By L. F. Zeiler

In the past, health concerns in coal mines have primarily centered on those elements which have been essentially inherent to the mining environment. These would include respirable coal mine dust, respirable crystalline silica, excessive noise levels, and diesel exhaust particulates. Commercially-available chemical products are prevalent on mine property. These potentially toxic materials are chemical formulations that can degrease, clean, and lubricate metal parts, separate coal from rock in float/sink operations, and aid in roof consolidation, among other uses. As the general public has become more aware of the hazards of chemical exposures, miners have likewise become more concerned about working with an ever-expanding variety of chemical products on the job. Often, product or chemical specific hazard communication training is inadequate or ineffective, and miners do not know exactly what the ingredients are in the products they handle, or the health hazards involved with their use or misuse. Currently, the Mine Safety and Health Administration (MSHA), by law, enforces 1972 Threshold Limit Values (TLV). MSHA is making preparations to adopt new personal exposure limits for enforcement. The values given throughout the article are 1994 TLV&apos;s and are not enforcement standards, but are used for discussion purposes. They reflect the current scientific thinking regarding personal exposure to these chemical agents. An overview of these products is presented, and the potential health hazards associated with their use are discussed. Controls needed to prevent overexposures, such as proper handling procedures and personal protective equipment, are covered. Methods used to collect and identify contaminants are presented.

Jan 1, 1995

By Y. C. Kim

Using an exhaustive data set of Walker Lake, four different kriging techniques plus the inverse distance squared weighting were compared with regards to each one&apos;s performance in accurately estimating the block grades. The North-West quadrant of the Walker Lake data area was used because of its extreme variability of values and its distinct contour of the values. There were 1900 exhaustive data points in the selected area from which a total of 121 samples were drawn following the sampling strategy given in Isaaks and Srivastava (1989). The average of 5 x 5 exhaustive data points was treated as the true, known block grade. A total of 780 blocks, each block corresponding to the average of 5x5 exhaustive data points, were then estimated using the 121 sample points. The resulting estimates were then compared with the true known values to determine each technique&apos;s prediction performance. For this particular portion of the Walker Lake and for the given sampling strategies used, the obtained results for the global estimation are mixed. For the variable U which is much more variable, the rankings are; 1) Jackknife Kriging (JK), 2) Indicator Kriging (IK), 3) Inverse Distance Square weighting (IDS), 4) Ordinary Kriging (OK), and 5) Log-Jackknife Kriging (LJK). For the variable V, the results are; 1) OK, 2) IK, 3) JK, 4) LJK, and 5) IDS. When we apply several cutoff grades to the estimates to determine the conditional mean grades and tonnage, the above rankings generally get shifted around. Two exceptions to these cases are; a) UK for U and b) IDS for V. These two consistently ranked at the bottom.

Jan 1, 1995

By Z. Y. Hu

This paper reviews the past and presents the present state of industrial minerals in China. The resources, reserve and production of major non-metallic minerals are given. The mining and milling operations are reviewed. The future development and plans of Chinese non-metallic minerals industry are summarized.

Jan 1, 1990

By K. C. Liddell

Chemical processing research made notable advances during 1986. This overview is necessarily brief. It is intended, though, to give the flavor of selected areas where recent activity has been high. At the 1986 Annual Meeting of The Metallurgical Society, a symposium was held on hydrometallurgical reactor design and kinetics. R. G. Bautista, R. J. Wesely, and G. W. Warren edited the resultant proceedings volume. This is the first available volume on this subject. It includes 26 papers on fundamental kinetic studies, modeling of reaction kinetics and reactor performance, and pilot and production-scale operations. Metals discussed include silver, gold, platinum, titanium, cobalt, nickel, zinc, copper, manganese, and iron. Agitated tanks, heaps, dumps, pachucas, pressure auto-claves, electrolytic reactors, liquid membranes, and fluidized beds are among the reactor types covered. An international symposium dealt with iron control in hydrometallurgy. It was sponsored by the Metallurgical Society of CIM, the Institution of Mining and Metallurgy, The Metallurgical Society of AIME, and Gesellschaft Deutscher Metallhutten and Bergleute. J. E. Dutrizac and A. J. Monhemius edited a proceedings volume containing 41 papers. These covered many areas of process chemistry, solvent extraction, precipitation, treatment of pickle liquors, impurities, residues and the environment, and process selection. Precious metals Concerning precious metals processing, the US Bureau of Mines IC 9059 is noteworthy. It includes papers presented at a USBM briefing at the Western Mining Conference in Denver. Topics covered included ion exchange, staged heap-leaching direct-electrowinning, and mercury precipitation during cyanide leaching of gold ores. Also dealt with were carbonaceous gold ores, carbon adsorption and desorption, heap leaching, the carbon-in-pulp process, and precious metals recovery from electronic scrap and solder. R. C. Sandberg and J. L. Huiatt (Journal of Metals, June 1986, and USBM RI 9022) developed a method to recover silver, gold, and lead from a complex sulfide using ferric chloride, thiourea, and brine-leach solutions. Gallium Gallium recovery was also a subject of considerable interest. Much information on this topic is proprietary. But two papers described solvent extraction of gallium. V. P. Judin and R. G. Bautista (Metallurgical Transactions B, 1986) developed an equilibrium model to separate gallium chloride from aluminum chloride. Tributyl phosphate was the extractant studied. T. Sato and H. Oishi (Hydrometallurgy, 16, 1986) investigated gallium extraction from sodium hydroxide by using Kelex 100. Data were given on the equilibrium distribution and the extraction kinetics. Galena Interest continues in recovering lead by hydrometallurgical processing of galena. J. E. Dutrizac; S. H. Kim, H. Henein, and G. W. Warren; and M. C. Fuerstenau et al. (Metallurgical Transactions B, 1986) all investigated leaching of PbS by ferric chloride. Dutrizac reported parabolic kinetics and reaction control by outward diffusion of lead through a porous layer of elemental sulfur. Kim, Henein, and Warren, however, reported that two leaching reactions occur. A nonoxidative reaction produces H2S and there is an oxidative leaching by ferric ion. Acid dissolution was found to predominate when the acid activity to ferric activity ratio is high. Surface chemical reaction was reported to be controlling. Fuerstenau et al. also reported that mass transfer through the sulfur layer is rate determining. But they believe that the species transferred are chloro complexes of ferric ion. In other work on lead, A. Y. Lee, A. M. Wethington, and E. R. Cole, Jr. of the USBM described an environmentally acceptable hydrometallurgical alternative to the smelting of lead concentrates (RI 9055). Uranium In spite of depressed prices, much work has been reported on uranium processing. R. G. L. McCready, D. Wadden, and A. March-bank (Hydrometallurgy 17, 1986) described the nutrient needs for in-place leaching by T. ferrooxidans. They reported the optimal conditions for uranium solubilization. L. E. Eary, H. L. Barnes, and L. M. Cathles (Metallurgical Transactions B, 1986) carried out an experimental and modeling study of uraninite dissolution. They concluded that ferric ion preferentially leaches uraninite in pyritic ores. Hydrogen peroxide was found to be less selective. A. Vuorinen, P. Hiltunen, and O. H. Tuovinen (Hydrometallurgy 15, 1986) studied redox and precipitation reactions of iron and uranium in leach liquors. P. T. Chiang (Hydrometallurgy 17, 1986) reported on the effect of uranium loading in the DEPA-TOPO process to separate uranium and iron from wet-process phosphoric acid. F. J. Hurst (Hydrometallurgy 16, 1986) conducted a fundamental study of the separation of uranium from phosphoric acid by DEPA and TOPO. D. E. Chia and W. C. Cooper (Hydrometallurgy 16, 1986) reported on bench and pilot scale work to recover uranium by the HIMIX process. They reported that the acid consumption to produce an eluate suitable for yellowcake

Jan 5, 1987