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By Selmar A. Oliveira

"Safe mine closure is an important step in the mining lifecycle. Plans for safe and efficient closure should begin at the inception of mining. Ideally, closure occurs when the reserve has been depleted. However, when the abandonment of a mine occurs prior to the depletion of the reserve, several problems arise which need to be treated. This situation occurred at Verdinho Mine, located in the state of Santa Catarina, southern Brazil. Verdinho Mine is a coal mine that operated for more than 40 years without had backfill technologies applied. Soon before the exhaustion of the reserves, it was abandoned by the owners without proper closure. As a result, the Federal Public Ministry filed a public civil action to promote proper closure. Several parties are currently involved, including the National Department of Mineral Production (DNPM), the mining regulator of the Brazilian Government. To meet the judicial determination, a cooperation agreement was initiated between DNPM and the Federal University of Rio Grande do Sul (UFRGS) to identify and to monitor parameters which could result hazard due flooding mine, to model the various conditions to minimize the impact of flooding caused by total abandonment. Many processes must be planned and planned early in mining operations, and these processes must be performed over the life of the mine. Financial resources must be guaranteed by a specific fund fueled by operating revenues. When these resources are not properly employed, costs and technical difficulties prevent proper closure progress. If the removal of subsoil equipment, treatment and control of groundwater, regeneration of the surface, and closure of openings are not done correctly, there can be environmental, social, and stability impacts over time. To avoid this in the future, a detailed study is being performed at the Verdinho Underground Coal Mine on how to appropriately implement mine closure and monitoring procedures. This study is being conducted in response to a lawsuit filed by the Federal Public Prosecutor’s Office. INTRODUCTION The nature of the Mining Industry is such that all mining is a temporary activity, where the operational life of a mine is defined by the final project scope. The operating life of a mine lasts from a few years to several decades. Mine closures occur once the mineral resource at a working mine is exhausted, or operations are no longer profitable. Mine closure plans are required by most regulatory agencies worldwide, such as the Mineral Production National Department (DNPM) in Brazil."

Jan 1, 2017

By R. K. Koch

The Bureau of Mines developed a zircon sand molding process for static casting of small titanium or zirconium shapes. Castings with unfinished weights up to 3.5 kg (7.7 lb) were produced in an inductoslag furnace and castings up to 7 kg (15.4 lb) were poured in a consumable electrode skull-casting furnace. Molds and cores were made by ram-molding, foundry-grade zircon sand (AFS gfn 93 to 95) bonded by grade D waterglass and tempered with water. Molds and cores were cured either at 250° C (482° F) or 900° C (1,652° F). Castings from the higher temperature molds broke cleanly from the sand while the lower temperature molds produced castings that had to be cleaned by sand-blasting. However, low-temperature cured molds and cores have a number of advantages as follows: (1) A faster, less energy-consuming curing cycle is used; (2) expended cores are water soluble which greatly facilitates core removal; and (3) enough of the binder in crushed expended molds is reactivated by temper water so that the molding mix can be reused five times without any fresh binder additions and up to twenty times without exceeding a total cumulative binder addition of 52 ml/kg dry sand. Crushed used molds that had been cured at 900° C had no detectable binding strength when mixed only with temper water. A large number of oxide and silicate mold washes were studied for improved casting integrity. The most effective wash found for zirconium or titanium casting was monoclinic zirconia (325 mesh).

Jan 1, 1977

By Stevak D, Plesingerova B, Ellias K, Tkacova K

This paper presents information on the processing of minerals by decrepitation that can be an integral part of their mineral dressing. In the case of carbonates, processing by decrepitation is a special operation that has its objective as concentration of the oxide. Selective fragmentation of magnesite brought about by decrepitation uses pseudomorphosis which was observed at thermal decomposition of carbonates. By decrepitation of magnesite high-grade MgO concentrates were obtained with MgO contents above 80 per cent. With the sideritic ores a very important phenomenon was observed consisting in the removal of quartz in the fragmented fine-grained product which favourably affect pelletisation of the fines. The selective concentration of the MgO product brought about by thermal decomposition of dolomite accompanied with decrepitation was negligible.

Jan 1, 1993

By Frank F. Aplan, Edward C. Jr. Dowling, Richard R. Klimpel

Thirteen kinetic models that mathematically describe the flotation process have been statistically evaluated for the flotation of copper, lead and zinc ores. Comparisons have been made for a variety of circuits involving roughing, cleaning, scavenging and regrind followed by cleaning. Variations in collectors, frothers, depressants and activators have been considered. Based on the statistical criteria used for the evaluation, and the reagent, circuit and ore variations studied, the most reliable flotation models have been identified and subsequently used to characterize the metallurgical results.

Jan 1, 1986

By Michael W. Hinds

X-ray Fluorescence Spectrometry (XRF) is used at various stages of gold refining. Initially, incoming impure gold is analysed for deleterious elements such as As, Cd, Hg, Se, and Te. Based on the levels of these impurities the material can be returned to the client or accepted for refining. XRF is also used to determine the metal concentrations after the impure gold has been melted and sampled. This information is used to assist the final Fire Assay determination of gold and silver. An energy dispersive XRF is used to determine the end point of chlorination refining step.

Jan 1, 2011

By R. W. Watson

A belt-wearable self-contained self-rescuer (SCSR) manufactured by the CSE Corp. and designated the "SR-1OO" was evaluated for safety in the underground mine environment by the U.S. Bureau of Mines. The evaluation consisted of laboratory tests on the chemicals contained in the unit and field trials to simulate the mine environment. This report summarizes the test results and compares the results with those from earlier tests with chemical and compressed oxygen self-rescuers. It was concluded that the new SCSR did not pose any different or more severe hazards than the earlier units. In view of the mine-proven safety record of the SCSR's now in service, no reason could be found to disallow use of the belt-wearable unit.

Jan 1, 1991

The influence of fuel additives on automobile exhaust emissions was studied using engines currently found in the U.S. vehicle population. The fuel additives used in the experiment were four multifunctional additives and one lead antiknock additive. Experimental work was done to determine both the direct effect of the additive per se on exhaust emissions and the influence of Long-term additive effects on emissions with mileage accumulation. Results showed no significant direct or intermediate effect on exhaust emissions for any additives tested. In subsequent experimental work concerned with the long-term or indirect effects of additives, the detergent-dispersant additives were found to have little influence on emissions when used in conjunction with high-quality oil and motor fuel. The lead (tetraethyl) antiknock additive increased exhaust hydrocarbons approximately 12 to 17 percent during a 4,000-mile accumulation period using a base fuel containing 2 ml of tetraethyl lead per gallon. An unleaded fuel was used during a similar accumulation period with no significant increase in exhaust hydrocarbons with mileage.

Jan 1, 1971

By De-qing Zhu, Feng Zhang, Jian Pan

Sintering performance of a series of sinter blends with high ratio of limonite was investigated. The metallurgical performance and mineralogy of product sinter were also examined. The results show that good sintering performance could be obtained when the ratio of limonite was below 43% in the blends of iron ore fines, while good microstructure and metallurgical properties were achieved under optimum sintering conditions. In contrast, sintering performance will rapidly deteriorate when the ratio of limonite is elevated up to 63% in the blends.

Mar 1, 2017

By Charles H. Rawlins

Reported is work done on processing of steel mill effluents in the areas of dewatering and separation. Much of the waste from these operations is in the form of sludges from scrubbers, in which the primary constituent is iron oxide. Recycling of the sludge&apos;s magnetic fraction has become economically attractive in order to reduce the overall volume placed in landfills. The objective of this research is to determine the effectiveness of combining magnetic and cyclonic forces, to recover iron oxide particles from waste water stream, while decreasing the volume to be disposed. Three different size hydrocyclones, operating within the field of a quadripole magnet, were tested using varying feed pulp densities of magnetite, magnetite/dolomite, blast furnace (BF), and basic oxygen furnace (BOF) slurries. In the first three cases, the percentage of magnetics recovered increased to greater than 95%. The limiting operational factors are; high pulp density for small cyclones, which can cause flow blockage within the magnet field, and extremely fine particle sizes (<2 microns), which cannot be recovered. The results indicate this technique can remove virtually all the magnetic particles from some steel effluents to a 40-50% weight percent solids pulp, on an in line continuous basis.

Jan 1, 1994

By SANDEEP KUMAR JENA

This paper reviews the recovery of potassium from different rocks and mineral sources. Global demand for potassium is rising steadily due to the growth of agricultural production. Fertilizer manufacture consumes the majority of the world’s potassium production, with other uses including those in the pharmaceutical, glass, ceramic, food and detergent industries. The availability of soluble potash (K2O) minerals, such as sylvite, kainite and carnalite, in countries like Canada, the United States, Israel and Russia makes them major potash producers, whereas agriculture-based countries like Liberia, Somalia, Central African Republic, Thailand, Indonesia, Malaysia and India meet their potassium requirements through imports only. In these countries, the huge availability of potassium-bearing rocks/minerals like nepheline syenite, feldspar, mica and glauconitic sandstone, containing around 4 to 17 percent K2O, brings up the prospect of commercial production of potassium. Potassium recovery from minerals/rocks is complicated due to the uniform distribution of potassium throughout the crystal structure. Different physico-chemical separation methods like bioleaching, chemical leaching, flotation and roast-leaching have been discussed for the successful recovery of potash values from these rocks/minerals. Although seawater is vastly available, the recovery of potassium from seawater using chemical precipitation, solvent extraction, membrane separation and ion-exchange methods is not cost-effective due to low concentration of potassium.

By Grafton M. Thrasher

For the proper discussion of this subject it is necessary to incorporate in this paper the substance of part of an article published by me in Metallurgical and Chemical Engineering for January, 1915. Several years ago, while I was chief chemist for a malleable-iron company, it occurred to me that the mere regulation of silicon was not sufficient to produce the desired degree of chill. But only after repeatedly encountering this fact in both open-hearth and air-furnace, as well as cupola metal, was I led to regard variation in the total carbon as the principal cause of disturbance; and I resolved to determine the total carbon as well as the silicon in every heat, and by a carefully prepared test piece to gauge the approximate degree of chill. The test piece selected was a round plug, 2 in. in diameter and 12 in. long, cast on end

Jan 1, 1916

By Bo Hyun Kim, Mark K. Larson

This study was developed as part of an effort by the National Institute for Occupational Safety and Health (NIOSH) to better understand rock-mass behavior in longwall coal mines in highly stressed, bump-prone ground. The floor-heave and nofloor- heave phenomena at a western US coal mine could not be properly simulated in numerical models using conventional shear-dominant failure criteria (i.e., Mohr–Coulomb or Hoek–Brown failure criterion). The previous numerical study demonstrated these phenomena using a user-defined model of the s-shaped brittle failure criterion in conjunction with a spalling process in the FLAC3D numerical modeling software. The results of the FLAC3D modeling agreed with the observations of the relative amounts of heave from each gate-road system. However, the FLAC3D model adopted many assumptions and simplifications that were not very realistic from a physical or mechanical perspective. To overcome the limitations of the FLAC3D model, 3DEC modeling in conjunction with the discrete fracture network (DFN) technique was performed to better understand the true behavior of floor heave associated with underground mining in an anisotropic stress field. The effect of stress rotation in the mining-induced stress field was considered by using a different geometry of rock fractures in the coal seam. The heterogeneity of the engineering properties (i.e., cohesion and tensile strength) were also considered by using Monte Carlo simulations. Consequently, the 3DEC models using the DFN technique resulted in predictions of floor heave that agreed with observations of the relative amounts of heave from each gate-road system, but the cause of heave was mainly related to the degree of anisotropy instead of the size of the pillar.

Apr 14, 2022

By T. S. Taylor

THE development of the linear hot-wire anemometer has been chiefly clue to the efforts of L. V. Kings1 and A. E. Kennelly and H. S. Sanborn.2 The anemometers used by these investigators consisted essentially of a fine heating wire having attached leads for resistance measurements at distances of 10 or more centimeters from each other. In using such an anemometer, the current is measured that is necessary to maintain the resistance of the wire, between the two leads, constant for different air velocities. Thus resistance is always so chosen that the temperature of the heating wire will be sufficiently high to make the observations practically independent of small variations in the temperature of the gas in which the anemometer is placed. The measurement of the resistance of the anemometer wire requires a Kelvin bridge set up, which for commercial work is not altogether desirable. The cooling effect clue to different air velocities depends on the temperature difference between the wire and the gas and the total quantity or mass of gas passing the wire per unit tine. Since the temperature of the wire is maintained constant, the effect observed in the change in the heating currentfor a given change in air velocity is a measure of the difference between the gas flow in the two cases. Such an anemometer, therefore, measures the average gas flow for a length depending on the distance between the two resistance leads. Therefore the instrument in the form used thus far is not very satisfactory for measuring gas velocities in small tubes or in places where the velocity varies rapidly across the line of flow. For the purpose of measuring gas flow through relatively small tubes, where the velocity changes rather rapidly across the tube, the hot-wire anemometer has been modified in the manner shown diagrammatically in Fig. 1. It consists essentially of a platinum heating wire H about 0.007 in. (0.178 mm.) in diameter and ½ to 1 in. (12.7 to 25.4 mm.) long stretched across a suitable framework, say of glass. This wire has

Jan 9, 1919

By T. A. Doyle

Column and batch test methods are used to simulate and model the leaching of various mining by-products. Batch tests are simpler, while column tests more intuitively represent the field conditions to be simulated. Projects that have included different types of leaching tests illustrate the strengths, limitations, and associated uncertainties of each. Column and batch tests have been used to evaluate arsenic solubility in leachate from treated copper smelter flue dust, to simulate the leaching of pit wall rock from a proposed gold mine, and to simulate the release of uranium from aquifer materials.

Jan 1, 1998

By Hongqiang Wang, Qingliang Wang, Eming Hu, Zhiwu Lei, Fang Hu, Rui Zhang, Wei Hou

Pyrite, a mineral associated with uranium ore, is closely related to uranium leaching. In this study, Ozone micro-nano bubbles (OMNBs), as an environmentally friendly advanced oxidation technology, were used for the first time to oxidize pyrite under experimental conditions to improve the leaching rate of uranium. A laboratory-scale agitation leaching experiment of pyrite was carried out with a pH of 1.0–3.0, gas flow of 1–3 L/min, ozone generation rate of 0.55–2.22 mg/s, and pyrite concentration of 0.1–5.0 g/L for 1 h. By adding three different co-oxidant: Mn(II), Mn(IV), and Fe(III), it was found that only Mn(IV) increased the oxidation rate of pyrite by 21.7%. The results of the scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) show that the formation of Fe(III)-O film on the surface of the ore suppresses the oxidation rate of pyrite to a certain extent. Pyrite can be rapidly oxidized up to 57.6% by OMNBs, which is beneficial to uranium leaching. This method is expected to be used for in situ acid leaching of uranium with OMNBs injected into the ground.

Jan 3, 2022

By W. K. Overbey

Surface fracture trace density, changes in roof rock type, and topographic unloading due to drainage were mapped for the mining areas located in the Blacksville-Osage, W. Va., quadrangles to investigate their influence on mine roof falls. Using these factors, a technique was developed to predict probable roof fall areas ahead of projected mining operations. As a feasibility test of this proposed technique, areas were delineated where one, two, and all three of these factors were operating to formulate a "potential hazard map" for comparison with roof fall observations that were made. The limited evidence suggests that in combination these factors are reliable predictors of where roof falls are likely to occur. This technique promises to be a useful tool in planning mining operations.

Jan 1, 1973

By Henry E. Blake

The Bureau of Mines has been engaged in a continuing research effort to develop processes for increasing the recovery and utilization of fluorine from low-grade resources. This current research has shown that over 98 percent of the fluorine in phosphate rock is extracted when the ore is treated with excess phosphoric acid in the presence of water vapor at 150° to 180° C. More than 80 percent of the fluorine can be recovered as fluosilicic acid, which can then be converted to commercially useful hydrogen fluoride or fluorspar by previously developed Bureau processes. Extraction of P205 from the ore was about 98 percent in batch tests and 90 percent in semicyclic tests.

Jan 1, 1974

By Bee R. Waples

The Alimak Raise Method, using the Alimak Climber, has proven to be a new, fast, economical method of driving raises at the Iron King Branch of Shat-tuck Denn Mining Corporation, Humboldt, Arizona. In order to fully understand the advantages of the Alimak Raise Climber, it is necessary first to describe the basic machine; second, a complete cycle of a raise round; and third, the comparative speed and economy afforded the Iron King operation by using this new method of raise driving: The raise climber consists of a drilling platform that is raised and lowered by two 6.2 HP compressed air motors that drive, through roller chains and sprockets, three worm gears connected in series. These worm gears drive pinions which grip the guide rail rack. The worm gems are fitted with spring-loaded couplings so that a small rock or grit in the rack is passed over without disturbing the mesh between the rack and the other pinions.

Jan 1, 1961

By D. C. Shumway

Mining in Cushenbury Canyon began in 1860 when John Cushenbury left his Holcomb Valley gold prospect and discovered a silver vein in the limestones of the present day Cushenbury Mine. Cushenbury Canyon is located along the western boundary of the Mojave Desert in Southern California and on the north slope of the San Bernardino Mountains. The Holcomb Valley, immediately southeast of Cushenbury Canyon was the most prolific gold producer in Southern California. Gold mining dominated the area until World War II when interest in the Lucerne Valley Limestone deposits was peaked by the construction of the Kaiser Steel Plant in Fontana, California. The steel making process required large amounts of metallurgical grade limestone and Kaiser geologists located claims in most of the limestone deposits. Kaiser Cement constructed a cement plant and limestone mine in Cushenbury Canyon in 1956. Kaiser Cement modernized the facility in 1982 to a four stage preheater-precalciner system. Mitsubishi Cement Corp. purchased the property in April, 1988, and through further system modifications have created the most efficient and modern cement plant in the United States.

Jan 1, 1992

By Karsten Beekhaus, Sander W. Odijk, Rabea Bahlum, Mazin Adnan, Ayman Abdelh Al Nuaimat, Hassan Farhat

The Arab Potash Company, APC, is one of the 10 largest potash producers of the world. The solar ponds at the Dead Sea, used for the enrichment of the salt content in the brine, are of crucial importance for the first step in the exploitation of the potassium salt. Targeting at the expansion of production in the since over 50 years utilized facilities, the increase of the brine exploitation capacity, reducing the substantial brine seepage losses from the ponds, becomes a crucially required measure. In this context, the remediation measures on the over 11 km long Dyke 1, being a main dyke of the solar ponds system, became inevitable to reduce the brine losses, prevent further development of sinkholes and cavities and hence assuring the stability of the dyke. The highly aggressive environment, the acting hydraulic conditions and the sensitive stratification and nature of the existing ground represented remarkable challenges for the design, as well as its implementation by the construction activities. Royal Haskoning developed a solution addressing the challenges above and targeting at a high sustainability of the executed structure, especially in view of the various geological and hydrological hazards repeatedly occurring in this Dead Sea region, including sinkholes of several meters by diameter and depth. The construction works, consisting of a cut-off wall, with depths reaching down to 31 m, were awarded to Bauer International FZE, a subsidiary of Bauer Spezialtiefbau GmbH. Upon the execution of the first section of 4.2 km length, additional sections were subsequently commissioned, also on further dykes, totaling to about 300,000 m² of cut-off wall. The specific project conditions, such as utilization of cutter technique for the excavation in Halite rock, the stability of open trench exposed to hydrostatic pressure of salt-saturated ground water, resulted in unconventional requirements towards the supporting fluid. The extremely aggressive saline conditions –with a Dead Sea water density of 1.25 tons/m3; one of the world's saltiest water–, were further a decisive factor for the definition of the backfill material concept. Despite its clear advantage for construction of cut-off walls with installed sheet piles, the single-phase system with hardening slurries, fulfilling both functions of excavation support and cut-off wall backfill material, had to be abandoned in favor of the two-phase system, to construct a hybrid cut-off wall made of sheet piles and plastic concrete.

May 1, 2022