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By Y. Topkaya, R. E. Johnson, B. R. Palmer, R. B. Bhappu, J. Brent Hiskey, Gürses Öner

Currently there is considerable interest in applying in situ leaching technology to recover copper from oxide ores. In many instances, the distribution of copper mineralization in these deposits is fracture controlled. Laboratory core-leaching experiments have demonstrated that leaching response is sensitive to the dissolution of copper from and the formation of channels along main fractures. Solution short- circuiting can be a major limitation of this technology. This paper describes the application of macromolecular polymers to achieve flow-profile control during leaching. Pre- and post-leached fractures were characterized by computerized tomography (CT) analysis.

Jan 1, 1993

By David Wilson, T. V. Rao

INTRODUCTION The Alchem trona mine, owned and operated by Allied Chemical Corp., is located approximately 32 km (20 miles) west of the town of Green River, and 8 km (5 miles) north of Interstate 80 in southwest Wyoming. Trona, a naturally occuring sodium sesquicarbonate (NaCO3 • NaHCO3 • 2H2O), is used for the production of sodium carbonate (Na2CO3), commonly known as soda ash. Present annual US consumption of soda ash is approximately 9.07 Mt (10 million st), out of which approximately 7.3 Mt (8 million st) is produced from the Wyoming trona mines. About 44% of soda ash is consumed by the glass industry; 3 % by exports; and the remaining portion by paper, chemical, soap, textile, and nonferrous industries. Allied Chemical operates an underground mine at an average depth of about 488 m (1600 ft). There are three other trona mines in the area operated by FMC Corp., Stauffer Chemical Corp., and Texasgulf Inc. (see Fig. 1). Allied Chemical became interested in southwest Wyoming trona deposits in the early 1940s. Explora¬tion work was begun in 1959 with the acquisition of federal leases. Exploitation of the reserves began in 1968. Two shafts, one 6.1 m (20 ft) and another 3.7 m (12 ft), were completed prior to 1968. The 6.1-m (20-ft) diam service shaft is divided in half by a cur¬tain wall, with one half used for men and material and the other for ventilation as a return air shaft. During the period from 1968 to 1974, the 3.7-m (12-ft) shaft was used as production shaft with two 7.3-t (8-st) skips. Due to the increased demand for soda ash, plant and mine expansions were completed during 1974. Under this expansion, the material handling system capacity was increased by constructing a new 2721-t (3000-st) capacity ore bin, sinking a 6.1-m (20-ft) diam produc¬tion shaft, and installing a friction hoist with two 22.7-t (25-st) skips. The Alchem mine manpower is 484 employees and about 2.3 Mt (2.5 million st) of trona was produced during 1976. Three different mining systems are used at the Alchem mine: conventional, continuous, and longwall. Allied Chemical introduced its first longwall unit in 1973, which was also the first longwall system introduced in the Wyoming trona district. At present, four conventional, seven continuous, and two longwall units are in operation. This equipment is operated in ten production areas. GEOLOGY The bedded trona and trona-halite in the Green River basin of southwestern Wyoming is a major re¬source for the nation. There are 25 beds that exceed 0.9 m (3 ft) in thickness and underlie areas of about 2590 km2 (1000 sq miles). There are other minor beds that range in thickness from 0.3 to 1.2 m (1 to 4 ft). Allied Chemical's Alchem mine is located in bed 17. The trona bed numbering system starts at the lowest elevation and increases upwards. The trona beds are in the Wilkens Peak member of the Green River formation. The Green River formation was deposited in a lake that began in early Eocene as a large body of fresh water, shrank in size and became saline, and then became fresh water again. The sedi¬ment during the saline phase of the lake, which includes the trona beds, is called the Wilkens Peak member. The underlying freshwater lake deposit is called the Tipton member and includes a 25.9-m (85-ft) sand unit which is a high pressure, low permeability aquifer. The over¬lying sediment is called the Laney shale. The Green River formation is underlaid by the Wasatch formation and overlaid by the Bridger formation (see Fig. 2). The structure of the beds in the area of the Allied Chemical mine is mostly postdepositional asymmetrical folds of small amplitude. These folds range in size of 3 to 6.1 m (10 to 20 ft) to as much as 45.7 m (150 ft). The trend of the folds is northwesterly with the north¬east flank of the anticlines having a steep dip and the southwest having gentle dips. Trona bed 17 varies in thickness from 2.4 to 3.4 m (8 to 11 ft) over the 93.2 km2 (36 sq miles) holdings of Allied Chemical and is flat lying except for the rela¬tively minor folding and a negligible regional dip of about 0.017 rad (1°). Trona occurs naturally in several physical forms in the Green River basin, being both massive and crystal¬line. The trona ore in the Alchem mine is a fine-grained massive ore with a compressive strength of approxi-

Jan 1, 1982

By John W. Amos, John A. Christophersen

The Deister No. 7, "77" and "88" Coal Washing Tables have been used by the coal industry in the cleaning of finer sizes of coal (-1/2") since washing of coals became necessary. This paper will deal with the in-plant use of the CONCENCO "88" Deister Coal Washing Table, along with a brief description of the Deister Refuse Superscalper. Efficient in-plant operation of the Deister Coal Washing Table can be accomplished by the adjustment of six basic variables. These variables are: 1. Headmotion 2. Feed 3. Riffle Pattern 4. Dressing Water 5. End Elevation Adjustment 6. Side Tilt Adjustment VARIABLE NO. 1 HEADMOTION The reciprocating movement of the "88" Table is developed within the headmotion entirely by rotating eccentric weights. Four parallel shafts each carry pairs of eccentric weights (Figure 1-A). The shafts are geared together with gears of 2 to 1 and 1 to 1 ratios, so that the two shafts in vertical alignment which carry the small eccentric weights operate at twice the speed of the other two shafts. The other two shafts are also in vertical alignment with each other and carry large eccentric weights. As power is supplied to one high-speed shaft, once each revolution the forces produced by the large eccentric weights are reinforced and then opposed by the small eccentric weights in a horizontal plane. The direction of movement of the table decks is reversed much more sharply at the forward end than at the backboard end of the stroke, causing material to move toward the refuse end of the table. Because in the vertical plane all centrifugal forces oppose each other and cancel out, there is no vertical movement and virtually no impact to the support steel. The "88" Coal Washing Table is suspended by wire-rope cables from three overhead steel beams, and operates with a perfectly uniform and exact differential motion curve in every stroke (Figure 1-B). The decks, being attached to the headmotion, are reciprocated in a parallel line from the head- motion to the refuse corner at speeds varying from 260-300 strokes per minute. Both length of stroke and speed are set at the factory for the coal characteristic desired and should not be changed. A 3 HP motor is mounted on the top of the headmotion and uses 3 V-belts to transmit driving power to the headmotion. The headmotion must be kept running on a horizontal plane. Punch marks are provided on the side and end of the main frame for use in leveling the motion (Figure 1-C). In leveling the motion, the work must always be done with two cables. To level the long side of the headmotion both front or both rear cables are raised or lowered to bring motion back to level. To level side to side, both right side cables or left side cables are raised or lowered to bring motion back to level VARlABLE NO. 2 FEED When tabling different size coals, each deck of a "88" DIAGONAL-DECK Coal Washing Table will handle feeds as described in figure 2-A.

Jan 1, 1988

By J. Reyher, R. Bratton, G. Luttrell, B. Li

"Flotation is regarded as the best available method of upgrading minerals and coal fines. However, its efficiency deteriorates rapidly with decreasing particle size. Further, ultrafine concentrates are difficult to be dewatered economically, forcing companies to discard part of the ultrafine materials to impoundments. To overcome these problems, a new method of separating and simultaneously dewatering ultrafine particles has been developed. Following extensive laboratory-scale test work, the process, known as hydrophobic-hydrophilic separation (HHS), has been tested successfully in continuous operations at proof-of-concept (POC)- and pilot-scale tests. The results show that the HHS process is capable of producing high quality clean coal with high recoveries and low moistures. INTRODUCTION Coal preparation plants are designed with up to four parallel processing circuits for treating coarse (> 12 mm), intermediate (12x1 mm) small (1x0.15 mm), and fine (<0.15 mm) particles. The plus 0.15 mm fractions can be effectively cleaned efficiently with gravity separation methods (Wills, 2006). At present, the only commercially viable option for cleaning the finest fraction is froth flotation (Yoon et al., 1999). In flotation, air is dispersed in the form of small air bubbles in a tank in which coal fines are suspended. The small air bubbles selectively collect the hydrophobic coal particles and float to the surface, forming a froth phase which overflows into a launder. As is well known, ultrafine coal particles of less than 30-50 µm are difficult to be collected by the air bubbles, resulting in low recoveries. Furthermore, fine particle flotation suffers from low carrying capacities and poor selectivity due to entrainment problems. (Bethell et al., 2005; Luttrell et al., 2014). In addition, the froth products containing ultrafine coal are difficult to dewater. Mechanical dewatering in general becomes inefficient with decreasing particle size due to small cake porosity and high surface area, resulting in high moistures (Hucko et al., 1988). The cost often becomes prohibitive with particles of smaller than ~45 µm (Bethell et al., 2005). Moreover, the high-moisture products are difficult to handle and incur high shipping costs and lower thermal efficiencies (Honaker et al., 2013)"

Jan 1, 2016

By N. B. Greninger, M. J. Sapko

The US Bureau of Mines conducted, through joint funding with the Colorado Mining Association, large scale oil shale rubble fire tests to investigate flammability characteristics and different methods of extinguishment. Ignition of large rubble piles was easily accomplished. Foam blankets could be used to control surface flames. The results of these large scale tests confirmed that water was effective but not particularly efficient in extinguishing deep seated oil shale fires. It took up to 1.7 times as much water to extinguish afire as anticipated on the basis of a simple cooling model, assuming 100% utiliza-

Jan 1, 1991

By David Martell, Wilf Ingram

For over 100 years mine hoists have been used in Cape Breton Coal mines which are situated on the eastern coast of Canada. Most of the coal seams have been inclined and as the mine advanced, longer lengths of haul were required. This paper describes the successful operation of slope hoists with rope capacities of up to 6100 m (20,000 ft.) at Cape Breton Development Corporation. A general description of the hoists is given. The braking systems, controllers and man riding cars used are discussed. The operational problems of using such long lengths of rope are described.

Jan 1, 1981

By M. J. Sapko

The US Bureau of Mines conducted, through joint funding with the Colorado Mining Association, large scale oil shale rubble fire tests to investigate flammability characteristics and different methods of extinguishment. Ignition of large rubble piles was easily accomplished. Foam blankets could he used to control surface flames. The results of these large scale tests confirmed that water was effective but not particularly efficient in extinguishing deep seated oil shale fires. It took up to 1.7 times as much water to extinguish afire as anticipated on the basis of a simple cooling model, assuming 100% utilization.

Jan 1, 1990

By J. Kallioinen

The paper describes industrial size experiments with a 100 m3 flotation cell validating the Size Specific Flotation concept and the Tank Cell design. It discusses some variables affecting the flotation of coarse particles. The results were good. The flotation recovery of coarse particles increased up to 50%. In finer sizes the flotation improvement was 5-15% The enhanced flotation of especially the coarsest particles increased the total recovery close to 10%-units compared to conventional cells in a porphyry copper flotation. The related power draw was only 50-80% of the power of conventional cells.

Jan 1, 1995

By S. D. Thompson, G. T. Lineberry, A. J. Basu

Conveyor belt haulage has become the preferred mainline transport method in underground coal mining, especially for multi-unit mines. Proper designs for belts (width and speed) and surge bins (placement, capacity, and discharge rate) are necessary to achieve efficient mine haul- age. Two computer simulation models, CMBCS and BELTSIM, available for designing these parameters were compared. These comparisons included modeling, input data requirements, statistical flexibility, accuracy of simulated loading, and execution time.

Jan 1, 1991

By P. Schmäh

Nowadays, small diameter tunnels are increasingly considered in pipeline projects as an alternative for sensitive crossings or when soil conditions limit the use of conventional pipeline installation methods like HDD. Safety concerns play a key role, especially for inner-city installations. Pipe jacked microtunnels and small segment lining tunnels can serve as casing tunnels if access is required during construction for the change of cutting tools in challenging ground conditions or for maintenance of the pipeline in operation. Small diameter tunneling solutions offer a high degree of flexibility for alignment design in terms of geology, length and radius.

Jun 13, 2021

By P. J. G. du Toi

Anaconda&apos;s experience with percussion longhole drilling in Butte, Montana, has consisted of six phases: 1. Drilling horizontal blast holes in stopes with push feeds. 2. Ring and parallel blast hole drilling in longhole stopes with bar mounted as well as skid jumbo mounted longhole drifters. 3. Ring and parallel drilling in raise climber shrinkage stoping using special raise climber drilling decks designed and built in Butte, Montana. 4. Parallel longhole drilling in horizontal cut and fill stopes with monorail jumbo. 5. Drilling water drain holes between mine levels. 6. Drilling leach holes through caved zones into old stope workings for leaching purposes. 7. Sample hole drilling.

Jan 1, 1970

By J. Hanna, J. Jung

Researchers at The University of Alabama have recently developed a two-step method for the treatment of phosphorus sludge. The process includes the bulk removal of phosphorus by physical separation techniques followed by the remediation of the residual P4 in the sludge using a novel, wet, air-oxidation technique known as "HSAD." Tests made on electric furnace, phosphorus sludge samples have demonstrated that an essentially complete and fast removal of the contained P4 can be achieved by the HSAD wet oxidation treatment. Further studies were made to determine the applicability of the two-step process to sludges of different origins, pretreatments, storage conditions and P4 contents. The present work discusses the mechanisms and factors controlling the HSAD, wet, air-oxidation remediation approach.

Jan 1, 1993

By Hans von Michaelis

ecent events have demonstrated the extraordinary impact of politics on the price of gold.... A rise from the $350/oz. level to $400 has a far greater impact on profitability of a gold mine than does, say, the invention of a way to cut the cost of gold extraction by $1.00 per ton, which in itself would represent a major achievement. Likewise, the discovery of a big, high-grade, easy­to-extract gold ore deposit would have a bigger impact on the fate of a mining company than, say, finding a way to double the energy efficiency of a grinding circuit.

Jan 1, 1990

By S. D. Bearden

The world&apos;s barite reserve base is adequate for at least 100 years at the current consumption rate. China, India and the United States are expected to remain the leading producing countries, and the United States will continue to be the largest consumer. None of the known substitutes for barium sulfate are expected to impact existing applications. World production in 1995 was 4.41 Mt (4.86 million st), which is about 50% of capacity. Consumption is directly proportional to hydrocarbon well installation activity. Imports are expected to continue to supply more than half of the US requirements.

Jan 1, 1998

By Q. Lin, D. Z. Wang

Molecular design plays an important role in development of new flotation reagents. Group electronegativity calculation is a main method of molecular design. It is commonly used in calculating the hydrophilic-hydrophobic balance of reagents, particularly in designing chain length of flotation reagents for located minerals. But there is a limit to group electronegativity method. The method can only apply to those of [Ø]known straight-chain compounds ([Ø] is the hydrophobic energy of each -CH2- , determined by experiment). In this Paper, we propose another new calculation method: fragment method of flotation reagent. The method could be used as a supplement of group electronegativity method to design and calculate flotation reagents without any limitation. With the fragment method, we can calculate the hydrophilic-hydrophobic performance of any known or unknown reagents including those complicate structure compounds such as cyclic, branch, heterocyclic and so on by summing the appropriate structural elements (fragment). The principle, calculation stages and some results of designing new-type flotation reagents by fragment method are presented in this paper.

Jan 1, 1995

By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors in¬fluencing the variation in face emissions between the two mines will be discussed.

Jan 1, 1997

By R. L. Grayson

In 1995, the United States Congress abolished the Bureau of Mines in the US Department of Interior. But Congress preserved the safety and health research functions being performed at the Pittsburgh and Spokane Research Centers. These functions were transitionally housed in the US Department of Energy before permanently merging with the National Institute for Occupational Safety and Health (NIOSH), Department of Health and Human Services, in October 1996. Since the rnerger of the former Bureau of Mines with NIOSH, there has been an active evaluation of ongoing research activities, significant interaction with stakeholders, and the development of a process leading to "data-informed" priority setting. This paper reviews the current surveillance information concerning the level of injury and disease from mining work and discusses how research priorities are evolving to improve the contribution of research to the prevention of injury and disease.

Jan 1, 2000

By Hans Skretting, Abraham A. Dor

This paper briefly reviews the historical development of the Rotary Kiln-Electric Furnace Process, which was first applied commercially to the treatment of qarnieritic ores in New Caledonia in the mid-fifties. It describes various technological improvements introduced, since, in industrial plants or developed in pilot facilities where a wide variety of nickel oxide ores has been treated success- fully over the years. Major categories of ores are characterized. The effect of their physical and chemical properties on their performance in the electric furnace is discussed. The relationships between ore composition, ferronickel grade and slag composition are analyzed and their effect on slag and metal tapping temperatures, nickel recovery, and electrode voltage are discussed.

Jan 1, 1979

By John W. Kelse

What happens when the skull and crossbones goes on a product? In the case of cancer warnings, the consequences can be severe. If the label contains the term "lung carcinogen", you might expect to compensate a lot of smokers, meet a lot of expensive lawyers, be counseled by equally expensive consultants and pay sharply elevated insurance premiums, if you are able to obtain coverage at all. At the extreme, you may face plant shutdowns, job losses or even Chapter 11 bankruptcy. Regardless of how you fare, you are likely to learn some very disconcerting things about the risk evaluation and regulatory system which required you to label in the first place. If a particular material or product does pose a health risk, you are obliged both legally and morally to warn those potentially exposed. Once that warning appears on the label, however, the consequences are often beyond your control. You and your embattled product become part of a legal/regulatory system which has a life of its own. Therefore, the issue of health labeling is not so much whether one warns but rather whether the warning itself is justified and the reasonableness of what happens afterwards. It is this matter of justification and reasonableness, particularly of cancer warnings, which this paper addresses. Until, as they say, your ox has been gored, we tend to believe that risk is determined by the best available technology and expertise We expect that risk evaluators appreciate the ramifications of their work and place things in proper perspective; that risk has been appropriately demonstrated before it is publicized and regulated; that the time-honored concept of prudence, to err on the side of safety, has not been excessively stretched. Unfortunately, the risk evaluation process is rarely, if ever, this

Jan 1, 1991

By Frank Matter

Production of ultrafine powders of industrial minerals has been a problem in the past. In recent years new wet and dry grinding stirred ball mill systems have emerged which have been commercialized Two such systems are the TRZK mill with double step air classifier for dry grinding and the NRZK mill for wet grinding The primary features of these mills are feed entering from top and the product along with the grinding media leaving from the bottom, and a media separation and recycle system A detailed description of the NRZK mill for grinding coal is presented

Jan 1, 1983