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By Thomas A. Gwynn

When Lewis and Clark first pushed their boats up the Missouri River, Meriwether Lewis reported the presence of coal in the western states by saying in 1802 that it "burnt tolerably well and afforded but little flame or smoke but produced a hot and lasting fire". Lewis would have been amazed and bewildered at the history of coal development in this region and the more recent political-socio-economic-environmental confrontations of today. Certainly without this coal the railroads would not have readily pushed into our western states, and the progress of this region would have suffered. The coal industry has passed from a period when "coal was king" to a period of depression in the industry, but its importance is being revived. A contributing and simultaneous environmental concern has emerged in the nation and in many states during the past ten years, partly caused by newly imposed standards for sulfur content of fuels. Much of the midwest and eastern coal cannot be used because of high sulfur content, shifting attention to the low sulfur coal deposits of the western states. In the western states, lands disturbed by strip mining or even underlain by strippable coal are small compared to the total acreage, and usually mining operations are on lands not under cultivation. There are some farm lands being disturbed by surface mining, but this is often over-emphasized. In states like New Mexico and Arizona the percentage is less. The value of the minerals underlying the surface certainly must be considered along with the value of the surface, and sometimes proper reclamation following mining can result in higher ultimate usage of the land.

Jan 1, 1974

By H. J. van Antwerpen

AngloGold Ashanti operates the world`s deepest mine, Mponeng gold mine, in South Africa. A vast refrigeration and ventilation system provides acceptable working conditions 3800m below surface at 60°C rock temperature. In such a system, optimisation and assessment of modifications becomes very difficult. With that in mind, a research project was launched to determine whether recently developed system simulation technology can be applied to a mine as vast and complex as Mponeng. Using the techniques and methods as implemented in FLOWNEX software, it was indeed proven to be possible to do a mine-wide combined simulation of compressed air flow, ventilation air psychrometry and refrigeration water systems. Interactions between the various streams included heat transfer, pressure drop, evaporation and condensation. The simulation model was used in a parametric study to test various water flow and temperature operating points for the refrigeration system. It was found that, given current limitations, the mine refrigeration system is running fairly close to optimal but with some opportunities for improvement. The simulation model also provided useful insight for future changes or extensions to the system.

Feb 23, 2014

By R. S. Shepard

The closing remarks of a paper which I presented at the annual AIME meeting at Dallas, Texas during February of 1963; contained a forecast of increased activity in trackless underground ore mining which finalized that presentation. At that time, HAD I been peering through my brightest rose colored glasses, I could not have foreseen the unprecedented rapidity of acceleration of underground ore mining methods which has since ensued. From Death Valley, California diagonally to St. Johns, New Foundland; from Australia to Africa to Sweden to France and Germany; from South America to Southern Mexico to Northern Saskatchewan and Northern Manitoba the expansion of trackless underground ore mining methods has probably progressed at a faster rate than any other revolutionary' change in the history of underground ore mining.

Jan 1, 1967

By William A. Gibson, Kenneth P. Neumann

In 1967, development of the Cyprus Thompson Creek molybdenum deposit began near Challis, ID. The first mining claims were staked on an intrusive rock out-crop. Exploration continued for 14 years. In 1978, the decision was made to develop the deposit. In Dec. 1980, approval was received for the environmental impact statement and facilities construction and waste rock removal began. By the middle of 1983, 126 Mt (139 million st) of rock had been removed and all facilities completed. Location The Thompson Creek project is located about 58 km (36 miles) southwest of Challis in Custer County, in south central Idaho. The mine and mill are situated between 2.2 and 2.6 km (7,217 and 8,530 ft) in elevation. The project is located in an isolated area. Surrounded by mountains, it is adjacent to the Sawtooth National Recreation Area. The Salmon river is 8 km (5 miles) south of the project. The project claim block is lo-

Jan 1, 1984

By Chengliang Jliang, B. K. Parek, Xuxin Shao

Of the impurities present in phosphate ore, dolomite is the most difficult to remove due to the similar chemical compositions of the impurities and also adsorption of dissolved species of dolomite onto phosphate. A new amphoteric surfactant was found to be a suitable collector for separation of dolomite from phosphate. Flotation results showed that the new amphoteric collector had a high flotation selectivity for dolomite in wide pH ranges. The flotation study of francolite and dolomite in each other's supernatant demonstrated that the dissolved ions had little effect on the selectivity of the new collector, but were detrimental to the flotation separation using sodium oleate as collector. A phosphate concentrate with 35.2% P2O5 with 90% recovery was obtained using 290 g/t of the amphoteric collector from a mixture of francolite and dolomite containing 26.2% P2O5. The rejection of MgO was 81.41%.

Jan 1, 1999

By J. D. Miller, J. Hupka

Important aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20-kg tar sand samples (Asphalt Ridge and Whiterocks, Utah) and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus, the tar sand porosity is a critical variable that determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, whereas for the Whiterocks tar sand (low porosity) the penetration process is much slower, being still incomplete after 15 hours regardless of the ambient temperature.

Jan 1, 1994

By Mengxiong Guo, Xuxin Shao

The recent depressant research is summarized, and a new kind of depressant (SCO) has been put forward in this article. Using Na-oleate as a collector and SCO as a depressant, separation of dolomite and phosphate was studied. When SCO was added in the concentration range of 80 g/t to 2kg/t at pH 9.5 ± 0.2, dolomite was absolutely depressed, and apatite kept its floatability. Interestingly, in the mixture of phosphate and dolomite, the dolomite floated. The reasons for such a behavior are investigated through flotation and electrokinetic studies. It was found that the adsorption of dissolved species on dolomite and phosphate resulted in reverse flotation. A concentration of 31.59% P205 and 83.87% recovery of P205 was obtained from the mixture of phosphate and dolomite (2:1) with 26.6% P205 using 210 g/t SCO and Na-oleate 4.93*10-5 M at pH 9.

Jan 1, 1989

By B. R. T. Simoneit

The conversion of organic matter to petroleum by hydrothermal activity is an easy process, occurring in nature in many types of environments. Geologically immature organic matter of marine sediments is being altered by this process in Guaymas Basin (Gulf of California), Escanaba Trough and Middle Valley (northeast Pacific), Bransfield Strait (Antarctica), and Atlantis 11 and Kebrit Deeps (Red Sea). Contemporary organic detritus and viable microorganisms are also converted in part to petroleum-like products by the same process when present to become entrained, as for example on the East Pacific Rise at 13o N and 21o N and on the mid-Atlantic Ridge at 26oN. The hydrocarbon products (methane to asphalt) generated in all these areas have been elucidated in terms of composition, organic matter sources, and analogy to reservoir petroleum. This petroleum represents a major input of carbon to the primary chemosynthetic productivity of hydrothermal vent systems and may be important to interactions with metals in hydrothermal ore formation.

Jan 1, 1991

By M. Prasad, G. M. Rao, T. C. Rao, A. K. Majmudar

A two-step flotation scheme was employed to beneficiate a low-grade, cherty-calcareous rock phosphate ore from the Jhabua district, Madhya Pradesh, India. In the first stage, apatite and calcite ire floated together to remove silica, and, in the second stage, calcite is floated and apatite is depressed. The reagent scheme consists of sodium oleate, sodium silicate, orthophosphoric acid and sulfuric acid. The effect of reagent dosages on the efficiencies of separtition in each stage was studied systematically. A flowsheet was proposed for the processing of a low-grade phosphate ore containing 12.5% P2O5, 26.5% SiO2 and a CaO/P2O5 ratio of 2.64 (=32% calcite). The proposed flowsheet would produce a composite phosphate concentrate containing 27.2% P2O5, 6.37% SiO2 and a much reduced CaO/P205 ratio of 1.66. The total P2O5 recovery for the composite concentrate would be 73% .

Jan 1, 1996

By R. A. Jankowski, J. D. Potts

Four underground respirable dust surveys were conducted to determine factors affecting belt entry dust levels and how using belt air to ventilate work areas affected dust exposures. Belt entry dust levels on the surveyed longwall and continuous miner section averaged 0.59 and 0.26 mg/m3, respectively. The stageloader/crusher contributed an additional 0.5 to 0.9 mg/m3 of dust to belt air, while the feederbreaker contributed 0 to 0.2 mg/m3 of dust. A 1000 ft (305 m) increase in belt entry length or a 200 to 500 tons/shift (181,000 to 454,000 kg/shift) increase in production resulted in roughly a 0.1 mg/m3 increase in dust. Using the belt entry as an intake entry on the continuous miner section appeared to reduce dust levels by 0.1 to 0.3 mg/m3 during cutting. Belt air was not used to ventilate the face on the longwall section.

Jan 1, 1992

By Jack S. Greber

The mining industry generates an estimated 2.3 billion tons of solid waste each year and the total accumulated mineral resource solid waste at both active and inactive mine sites, approaches 30 billion tons. Five industries generate 85 percent of mine solid waste: copper, phosphate, iron, uranium, and coal. Over the past several years, the Federal government has shown increasing interest in the proper disposal of solid wastes generated by the mining industry. Three new pieces of federal legislation have been passed recently beginning with the most comprehensive regulatory authorization passed in 1976, the Resource Conservation and Recovery Act (RCRA) which has been amended to the Solid Waste Disposal Act Amendments of 1980. RCRA is implemented and enforced by the Environmental Protection Agency (EPA) and intended to control municipal and industrial solid wastes. Next came the passage of the Surface Mining Control and Reclamation Act (SMCRA) of 1977 which is implemented and enforced by the Department of Interior to control coal surface mining and the surface effects of underground coal mining, and finally, the recent Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978 implemented by EPA and enforced by the Nuclear Regulatory Commission (NRC) to control uranium mill tailings disposal.

Jan 1, 1981

By Robert S. Holmes

The U. S. Army Corps of Engineers Explosive Excavation Research Office (EERO) of Livermore, California, has been engaged in research and development of excavation techniques using both nuclear and conventional explosives since 1962. Prior to July 1971, this organization was designated the U. S. Army Corps of Engineers Nuclear Cratering Group. The EERO mission is performed as part of the joint Atomic Energy Commission -Corps of Engineers nuclear excavation research pro-gram. During the period 1962-1969, the Corps executed many cratering explosions using spherical charges of up to 85 tons of nitromethane to model nuclear excavation concepts and to develop design criteria for the nuclear cratering explosions. The experience gained in these modeling tests suggested that explosive excavation using large chemical explosive charges could be applied to excavation projects as an economical substitute for traditional excavation techniques. Consequently, the Corps' research program was broadened in 1969 to include development of chemical explosive excavation as a construction tool. The term "explosive excavation" denotes the use of large buried explosive charges to produce an excavation by fracturing the material and casting it into a desired configuration. In its simplest form, this technology involves detonation of a single explosive charge buried at the proper depth to produce a crater which is roughly hyperbolic in cross section. The types of craters produced by various depths of burial are illustrated by Figure 1. Single or Multiple rows of charges are used to excavate linear cuts required for water conveyance or navigation channels. .More complex explosive excavations include small craft harbors, railroad and highway cuts, and removal of W1denvater rock barriers to navigation. While the literature indicates widespread use of large explosions in the (1) ERRO is a field activity of the Waterway Experiment Station, Vicksburg, Mississippi

Jan 1, 1971

By G. Mei

"This study explores froth flotation and selective flocculation methods to recycle waste phosphors containing several rare earth elements, namely, yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb). The effects of the presence or absence of collector and of flocculant and their dosages, as well as the pH, were investigated. Reverse flotation resulted in concentrates with grade of 27.03 percent and recovery rate of 71.36 percent, while flocculation resulted in concentrates with grade of 31.43 percent and recovery rate of 91.28 percent. The flotation and flocculation behaviors were further analyzed by X-ray diffraction analysis, zeta potential measurements, particle size distribution and other methods. The successful separation of rare earth minerals by flotation was attributed to the selective adsorption of the collector onto quartz, making it particularly recoverable by reverse flotation so as to be separated from the valuable materials. The analysis of the particle aggregation process indicated that its better flocculation performance was due to the selective adsorption of flocculants onto the unwanted materials, enlarging the flocculant sizes by forming aggregations and facilitating the separation of rare earth minerals from waste materials based on different settling rates. IntroductionBecause waste phosphors pose the problems of heavy environmental burden and high risk to human health (Hu and Cheng, 2012) as a result of containing heavy metals such as mercury and manganese (He et al., 2006; Lucas and Emery, 2006), they have received added attention as urban mining resources for extracting rare earth elements (REEs) like yttrium (Y), europium (Eu), cerium (Ce) and terbium (Tb).At present, chemical processes such as acid leaching, alkali fusion, roasting and extraction are the primary methods for recovering REEs from waste phosphors (De Michelis et al., 2011; Li et al., 2012; Li, 2010). With these strategies, phosphors can be effectively decomposed and their REEs extracted. After the removal of impurities, the REEs can be efficiently precipitated by adding an H2C2O4 solution (Porob et al., 2012). Although relatively high recovery rates are achieved, those processes entail high energy consumption and can cause severe environmental pollution."

Jan 1, 2017

By I. Douni

The aim of this study is to synthesize hydrated compounds of calcium silicate (tobermorite) using as siliceous source perlite milling process wastes, containing more than 70% of SiO2. Calcium silicate hydrates are mainly used for construction of lightweight building materials, plasters, tiles and filters. The effect of temperature, time and particle size of perlite on the quality and composition of the solid product was studied. The solid products were characterized by X-ray Diffractometry, Differential Thermal Analysis and the amount of Acid Insoluble Residue. The synthesis of tobermorite was per-formed by the hydrothermal treatment of perlite waste with a saturated calcium hydroxide solution at a molar ratio CaO/SiO2 of 1, liquid to solid ratio 10 mL/g and 1% w.t. NaOH addition. Three experimental sets were performed. In the first series of experiments the synthesis temperature was kept constant at 205°C while the synthesis time varied from 0.5 h to 24 h. In the second experimental series the synthesis time was kept constant at 2 h while the temperature varied between 150°C and 245°C. In the third experimental set the temperature was 205°C and the reaction time was 2 hours and two perlite waste size fractions were used, a coarse (d50=18 µm) and a fine grained one (d50=8 µm). Reaction products consisted of semicrystalline calcium silicate hydrate (I) and crystalline Al-substituted tobermorite or a mixture of both. An isomorphic Si4+ ions substitution with Al3+ ions in the hydrated calcium silicate lattice was detected by thermal analysis. The experimental results show that good quality crystalline Al-tobermorite can be produced after 6 hours of autoclaving at 205°C or after 2 hours of hydro-thermal treatment at 225°C. Generally, the in-crease of synthesis temperature or time favors the crystallization of calcium silicate phases and enriches them in aluminum. The use of fine grain size perlite is more efficient for the hydrothermal synthesis of calcium silicate hydrates.

Jan 1, 2006

By Leandro Augusto Viana Teixeira, Angela Avelar, Ruberlan Gomes Silva, Virginia S. T. Ciminelli, Daniel Majuste

Rare earth elements are essential for modern life products and green technologies. Recent supply constraints have boosted the development of rare earth projects after the price peak of 2011. The feasibility of a project depends on the definition of a processing route, which in turn depends primarily on the rare earth mineral, with monazite and bastnaesite representing the two most relevant minerals. Monazite-type ores usually contain high acid consumption impurities, such as iron, aluminum, calcium, magnesium, and phosphates, and may also contain prohibitive levels of radioactive thorium in its composition. This work presents a thermodynamic analysis of a monazite system and discusses the fundamentals of a selective process route for rare earth extraction from monazite ores with high iron content. This process involves sulfation by means of concentrated sulfuric acid and roasting at a high temperature. The route yields high rare earth extraction with low iron and thorium extractions and low acid consumption. Rare earth extractions as high as 80% were achieved, while iron and thorium extractions were lower than 1%, and acid consumption was lower than 0.34 kg of sulfuric acid per kg of ore. The operational window was compared to the one predicted by thermodynamic modeling, with 700 °C representing the optimal roasting temperature

By Morgan M. Sears, Gamal Rashed, Michael M. Murphy, Brent Slaker

In this study, a parametric study was conducted using FLAC3D numerical models to examine the impact of oblique loading, generated from seam dip, on the strength and the failure propagation pattern of a stone pillar using two simplified geometry types. In type 1, the sidewalls of the pillars were assumed to be perpendicular to the roof and the floor, while in type 2, the sidewalls of pillars were assumed to be vertical. The complex pillar geometry in dipping mines was frequently modeled using these two geometries. To capture a complete picture of the effect of seam dip on pillar stability, the modeled width-to-height (W/H) ratio of the pillars, in situ stress field, and pillars roof/floor interfaces were systematically varied to account for the potential distribution of values for these parameters across the underground stone mines in USA. Results from the numerical modeling indicate that dipping pillars have reduced strength compared with horizontal pillars. Also, an asymmetric failure propagation pattern could be obtained depending on an interaction between the W/H ratio, seam dip, in situ stresses, and pillar geometry.

Feb 5, 2021

By T. Tamagawa

A gaseous chlorination process for hydrometallurgical treatment of a chalcopyrite concentrate was investigated. The overall process is visualized to consist of low temperature chlorination-selective oxidation, followed by aqueous chloride leaching and SX-EW for producing electrolytic copper elemental sulfur and ferric oxide. In this article, the chlorination phase of the processes is described. Initially, the chlorination behavior of chalcopyrite-concentrate micro-pellets was investigated using a small batch-type fluidized bed reactor. The optimum conditions thereby established was used in continuous chlorination tests. The chlorinated products thus prepared were used in the selective oxidation phase of the investigation.

Jan 1, 1999

By Kallam V. K. Reddy, VADAPALLI SANJANA, Veerendra Singh, Gajanan Kapure

This work describes a leaching process for the conversion of high-magnesium peridotite rock, which is a chromite ore overburden, into two valuable products: magnesium salts and micro silica. Under normal leaching conditions, residue remaining after leaching is of a gelatinous nature and thus hinders the filtration process. To address this issue, oxidative leaching with the addition of H2O2 was employed, and it significantly improved the filtration kinetics. Four different approaches for H2O2 addition were tried, and they all proved effective in controlling gelation. The optimum oxidative leaching condition was 70 °C, 2 h time, 2 M H2SO4, 0.5MH2O2 and 400 RPM; under these conditions, 92% magnesium leaching efficiency was achieved. After leaching, the leach liquor obtained was purified and dried into Mg(OH)2 and MgSO4 salts. The leach residue contained mainly silica particles, with size in the 10–30 μm range. This material thus represents an attractive candidate for the production of highperformance concrete for the construction industry. The oxidative leaching process described here enabled the complete conversion of peridotite into valuable products, magnesium salts and micro silica.

May 5, 2020

By B. Pesic

The recovery of silver and gallium from flue dust with acidified thiourea solutions was examined. The studied parameters were temperature, particle size, thiourea concentration, acid concentration, and the presence of oxidants. The study of the extraction of these two metals was undertaken in sulfuric acid medium. Silver dissolution was dependent on all examined parameters, whereas gallium extraction was only dependent on the initial acid concentration. The experimental results suggest a new very efficient method for recovery of both silver and gallium. Almost complete recovery of silver and gallium can be accomplished within 90 minutes. A technological scheme for recovery of both metals is also proposed.

Jan 1, 1986

By Changjiang Li, Jun Yang, Qiang Fu, Xu Chang, Xing Wu, Yubing Gao

With the development of underground mining, the deformation of roadway floor has increasingly become a major constraint on the safe and efficient production of coal mines. To address the floor deformation that was caused by massive stress concentration in roadway, an innovative method based on deep-hole directional tensile blasting technology is put forward. By taking No.122108 working face in Caojiatan Coal Mine as engineering background and analyzing the mechanism of deformation, a numerical simulation and field test are carried out to verify the effect on deformation control of this technology. It is found that the deep-hole directional tensile blasting technology can actively control the fracture position of the roof in the gob area and cut off the stress transmission path, so as to relieve the stress in the roadway. And since different blasting parameters have different impacts on the stress relief effect, a numerical simulation is implemented and it is found that the stress relief effect is the best when blasting depth is set to be 32 m and the blasting angle be 60°. By applying the optimal blasting parameters to the field engineering test, it can be seen that the deep-hole directional tensile blasting technology could effectively reduce maximum stress value and stress field range of the both sides of the roadway, and make the stress field far away from the roadway, thus effectively controlling the deformation of the roadway floor. The deep-hole directional tensile blasting technology can effectively solve the problem of roadway floor deformation and can be safely applied to engineering sites.

Jun 13, 2023