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By Debasis Barman

TBM (TBM) mining in urban areas particularly under low overburden is a big challenge to design and excavate. During excavation of the Lucknow Metro project, in Uttar Pradesh, India the metro authorities encountered a design stretch where the TBM had to cross a sewer canal crossing of 15 m length under overburden of less than 1 m. Not only the stability of TBM due to uplift was of concern but also the stability of both banks. Most structures on the canal banks were non-engineered structures whose stability due to vibration of TBM was also of concern. Due to these risks, a method was proposed that met stability requirements for both ground and superstructures. The design was practical and cost effective to construct, and a collaborative exercise between the client, contractor and designer that took approximately 18 months to implement.

Jun 13, 2023

The exploitation of the underground is currently undergoing a major transformation process. Besides mining, alternative ways of utilization are playing an increasingly important role. These alternative utilizations include the storage of gases, the disposal of radioactive wastes and the implementation of geothermal storage facilities. In addition, more and more mining operations are being shut down, like the German hard coal mining industry in 2018. But the integrity of closed mines must be ensured in the post-mining phase.

Jan 7, 2020

By Wu Aixiang, Zhou Qian, Zhou Zaibo, Liu Juanhong, Wang Hongjiang

To improve the pumping capacity and engineering efficiency of fresh thickened tailings slurry, a high charge density superplasticizer was developed to improve the rheological properties of tailings slurry. The effects of superplasticizer content, the concentration and fineness of tailings, the proportion and type of cementitious materials, temperature, and hydration time on the rheological properties of unclassified tailings slurry and backfill materials were studied. The variation characteristics of the slurry yield stress, plastic viscosity, and thixotropy with different factors were measured by a Brookfield R/S-SST plus rheometer. The experimental results of fresh thickened tailings illustrated that the higher the concentration of the slurry and the finer the tailings, the worse the rheological properties of the slurry. The results of cemented paste backfill materials indicated that the rheological parameters increased as binder content and time increased. The rheological parameters decreased as the temperature increased. The addition of a superplasticizer reduced the rheological parameters and improved the rheological behavior of the fresh thickened tailings and cemented paste backfill materials, which was beneficial to the slurry’s pipeline transportation. This paper can provide technical guidance for slurry transportation in the backfill system and provide a reference for designing the superplasticizer used in tailings.

Jan 5, 2022

By Wilbur J. Morin

Construction of Flaming Gorge Dam in northeastern Utah necessitated the construction of a new state highway, Utah-260, to provide access to the dam and the town of Dutch John. A 550-foot arch structure was designed to span Cart Creek, about one mile southwest of the dam. The rock exposed at the site is highly fractured quartzitic sandstone with interbedded shale of the Precambrian Uinta Mountain Group. Eight exploratory holes were drilled, four in each abutment area, to determine rock types, the extent of fracturing at depth and rock strength. Drill cores in the west abutment revealed blocks of quartzitic sandstone loosened by the weathering and partial removal of underlying shale beds. The rock in the east abutment area was found to be highly fractured to depths of 70 feet and as far east as 50 feet from the footing locations. Selected core sections were tested for unconfined compressive strength but the values were not considered-representative of the in-situ fractured rock. To prevent movement along or, perpendicular to open fractures, four drilled-in columns were provided at the base of each footing. These extended 50, feet beyond the base of the footing, along the bearing and inclination of the thrust reaction.

Jan 1, 1963

By C. G. Anderson

The treatment of concentrates for the recovery of the precious metals imposes many processing and environmental challenges. Hydrometallurgical technology for recovery of values from refractory precious metal materials has been developed at Sunshine Mining and Refining Company. Historically, conventional pyrometallurgical methods have been used for to recover values from refractory precious metal materials. However, enhanced environmental awareness has worked to constrain typical refractory material processing methods. This hinders and limits the ability of established smelting or roasting technologies to fill the needs of new sources of refractory materials. An alternative is to treat refractory precious metal bearing materials by hydro metallurgical techniques. These methods are considered more environmentally appropriate since they do not produce gaseous pollutants like sulfur dioxide. Industrially, Sunshine Mining and Refining Company employs hydrometallurgical technology to process refractory precious metal materials. The Sunshine antimony leach uses a mixture of sulfur and caustic under ambient pressure and boiling conditions. The Sunshine oxidation leach uses a mixture of sulfuric acid and a minimal amount of sodium nitrite under relatively mild oxygen pressure and temperature conditions. These conditions result in a nitrogen species catalyzed sulfuric acid pressure leach. Since hydrometallurgical technologies provide industrially proven processing options for many types of refractory precious metal containing materials, their usage should be considered. Ample work has been conducted to prove the effectiveness of Sunshine refractory processing technologies on various materials. This has included platinum group metal materials, refractory gold concentrates, silver materials and indium materials. In some cases, complete process flowsheets have been designed to recover both base and precious metals from these materials and to treat the generated waste streams in environmentally sound manners.

Jan 1, 1996

By Stephen J. Swan

Feed-forward control (i.e. the forward flow of information in a control system ) is a simple and flexible approach to over-all control of a ball mill-rake classifier grinding circuit. The system described here uses mill power, feed rate, mill dilution water flow rate, and classifier dilution water flow rate only, to control mill load, throughput, mill solids, and classifier solids as well as classifier overflow grind. The mill load is controlled by a simple feed-back control loop, while mill solids and overflow grind are controlled within close limits by a unique non-linear feed-forward water control system. In effect the control follows a limited mathematical model of the grinding circuit. The configuration minimizes deviations in overflow grind due to changing ore conditions, but since it is open-loop, and the model is not complete, it is affected by changes in total ball charge and liner wear. These effects are fortunately gradual, and changes in the grind can usually be kept to within ± 1% of a target continuously for several days without adjustment. Control adjustments are made with feed-back from laboratory composites. This control system has won enthusiastic operator acceptance; it is easily started up and shut down; grind-outs have been eliminated along with flotation machine flooding and mill spills. Standard measurements and components are used throughout providing a trouble-free system design at a moderate cost.

Jan 1, 1970

By A. D. Walters

Computer simulation models of preparation plant operations and cost analysis have been used to determine the profitability of individual coals. The model's input consists of raw coal size and washability analysis, operating cost data, and raw coal and clean costs. The model's output predicts yields, qualities, costs and profitability for an individual coal.

Jan 1, 1987

By G. W. Phelps

This discussion deals with the geology o£ the Tennessee-Kentucky ball clay deposits; their mineralogy and chemistry; methods of finding, mining and refining; and makes observations on reserves of and future prospects for these clays. Ball clays appear in ceramic formulas for manufacture of vitreous china sanitary-ware, electrical porcelains, floor and wall tile, dinnerware and artwares(l). This type of clay is used for refractory (2) and abrasive products(3), and as a suspending agent for ceramic glazes(4), engobes(5) and porcelain enamel slips(6). Although some ball clay is imported, probably 85-90 percent of ball clay used in the USA(7) is obtained from deposits in Weakley, Henry and Carroll Counties in Tennessee(8), and in adjacent Graves County, Kentucky(9). The term "ball", as applied to clay, probably derives from former mining practice in England whereby conveniently-sized blocks of clay were cut from moist clay beds by spading(10), The expression "ball" has no other technological significance. ASTM(11) defines ball clay as "a secondary clay, commonly characterized by the presence of organic matter, high plasticity, high dry strength, long vitrification range, and a light color when fired." This, and similar(12) definitions, applies to English ball clays but is not satisfactory for many American ball clays. Geology of the Tennessee-Kentucky Ball Clay Deposits Figure 1 shows that most commercial clay areas of the eastern United States lie near the edge of the Coastal Plain; a skew-shaped configuration of its landward boundary outlines the Mississippi Embayment(13), Near the apex of this basin a broad plain, with a rolling, Bullied topography(14), dips gently westward from the Tennessee River to bluffs at the edge of the Mississippi River flood plain.

Jan 1, 1972

By A. M. Raichur

Flocculation of fine coal is usually accomplished with the addition of commercially available organic flocculants. Recently it has been shown that biopolymers derived from microorganisms can be used to flocculate coal. The biopolymers flocculate coal efficiently and render the coal surface hydrophobic. The increase in hydrophobicity can be utilized either to separate the coal flocs from mineral matter. It can also be used for reducing the moisture content of fine coal. In this regard, flocculation and settling tests of fine coal with biopolymers and synthetic flocculants was undertaken and the results are discussed here. Also, a transport model was developed for the time-dependent settling tests for fine coal.

Jan 1, 1996

By M. Mankosa, G. Taylor, G. Luttrell, J. Yasalonis

Several industrial-scale HydroFloat separators have recently been installed at Mosaic’s South Fort Meade beneficiation plant for the purpose of improving phosphate recovery and throughput capacity. This technology was implemented after numerous laboratory, bench-scale, and on-site, pilot-scale test campaigns. The results from this detailed test work provided sufficient justification for the complete retrofit of the existing coarse and ultra-coarse flotation cells. Data indicate that the metallurgical results obtained with the full-scale separators are consistent with that obtained during both the bench- and pilot-scale evaluations. The apparent benefits, theory of operation, and commissioning of the equipment are also discussed.

Jan 1, 2007

By Gary R. Krieger

Baseline Risk Assessment: - Data Collection and Evaluation - Exposure Assessment - Toxicity Assessment - Risk Characterization Lead - Problems and Pitfalls: - Sources - Pathways - Receptors - Toxic Endpoints - Modeling Options - Health Based Clean-Up Options

Jan 1, 1990

By S. A. Moffatt

For several years iron ore processing plants, located in the northern U.S. experienced seasonal decreases in the grinding efficiency of their primary autogenous mills. Kawatra and Eisele (1992) studied this phenomenon in an operating plant and characterized it in terms of specific energy consumption (Fig. 1) and production of critical size material (Fig. 2). Critical size material is defined as ore that is too small to be effective grinding media and too large to be ground. This data showed that both specific energy consumption and critical size production increased during the winter months. The increased energy consumption was in part a result of an increase in the viscosity of the mill pulp at colder pulp temperatures. However, viscosity could not fully explain the changes in critical size production. These changes are most likely due to changes in the breakage characteristics of the ore. Other studies were also conducted to determine if thermal and physical properties of iron ore changed at colder temperatures. These are summarized below:

Jan 1, 1993

By R. W. Lake

The decision to develop an ore body can lead to multi-million dollar profits, or equally substantial losses. Accordingly, the effort required to adapt a valuation model to the specific proposal at hand, or even the development of a new model from basic principles, is clearly warranted. In the formulation of a model of this nature, one is faced with some major questions. For example, with the long term obligations that it implies, on what basis should a decision to initiate mining operations be made? Furthermore, how can the vagaries of inflation and the uncertainties that shroud the future be accommodated? Beyond the general principles by which mineral deposits are evaluated, specific cost behaviour is a function of the geology of the deposit, and of the mine design. Moreover, mine design, during the life of the mine, must be a continuing process somewhat akin to dynamic programming. An initial, apparently optimal, design is selected and mining commences. With production, a continual process of information updating leads to revisions. Thus if the maximum value is to be obtained, the mine design must be adjusted to conform to the changed conditions.

Jan 1, 1977

By Graham A. Brown

Activities in offshore mineral exploration In Australia are increasing almost daily, at such a rate that this report will rapidly become out of date. At the time of writing, February 1967, there were no commercial discoveries of offshore minerals reported in Australia, although there has been definite encouragement in many fields. While this initial encouragement has not revealed any commercial mineral deposits offshore hopes are running high in Australia for success in 1967. Why should mineral deposits be expected offshore in Australia in the first place? The reasons are many. The minerals to be discovered also are many. The reasons are based on the history of alluvial and beach mining activities in Australia's past and at the present time, and on the physical environment of the vast Continental Shelf which surrounds the continent. A brief examination of the two primary features which are necessary before offshore mineral exploration can be contemplated should be, undertaken. Two favourable environments are necessary; firstly a Continental- Shelf to form a physical environment for the accumulation of the mineral deposits, and secondly a favourable political-legal environment to give the exploration companies adequate protection during exploration, and suitable long term arrangements for the exploitation of the deposits after discoveries have been made. Australia is well endowed with both of these.

Jan 1, 1967

By W. A. Crosby

All mine operators using explosives want to maximize explosive performance while minimizing blasting costs. Use of bulk explosive products such as AN/FO, heavy AN/FO, slurries and emulsions has greatly improved blasting efficiency over the years. Many operators have improved energy output from these products by adding aluminum. A major problem facing them is the fluctuation in aluminum price. The question therefore becomes, when is it economically advantageous to use aluminum in bulk products? This paper answers this question by first reviewing the energy output from the main types of aluminized and non aluminized bulk mixed explosives and then by showing the relationship between the different products on a cost and energy basis. The paper finally presents examples of charts and tables which will aid mine operators to conveniently select the most economically correct bulk explosive, including the level of aluminum addition.

Jan 1, 1991

By Roy A. Koski

This paper describes variations in feed characteristics, preparation techniques, response to induration and product quality in pelletizing magnetite concentrates, earthy hematite ore fines, and specular hematite concentrates in grate kiln systems. The Cleveland-Cliffs Iron Company manages plants processing these various materials on the Marquette Iron Range in northern Michigan. The operations include the Humboldt Mining Company, Marquette Iron Mining Company, Empire Iron Mining Company and the Pioneer Pellet Plant. The combined output of the operations is approximately 9,000,000 long tons per year. The Humboldt Mining Company, owned by Ford Motor Company and Cliffs, produces pellets from a specular hematite concentrate. The Empire operation, which processes magnetite ore, is owned by Inland Steel Company, McLouth Steel Corporation, International Harvester and Cliffs. The Pioneer operation, which processes earthy hematite ores, is a joint venture of Republic Steel Corporation, McLouth Steel Corporation, Bethlehem Steel Corporation and Cliffs. The Marquette Iron Mining Company, owned by hones and Laughlin Steel Corporation, International Harvester, Wheeling-Pittsburgh Steel Corporation and Cliffs, produces pellets from specular hematite concentrate at the Republic Mine and Eagle Mills Pellet Plant. With the exception of the Eagle Mills plant, the operations employ the grate-kiln pelletizing system. Descriptions of the Empire, Pioneer and Republic operations, which have a combined capacity of 7,200,000 tons per year, are given in the paper.

Jan 1, 1969

By Y. C. Lo

This paper attempts to answer whether or not the mill performance at Bougainville could have, in fact, been predicted by the population balance approach, or whether other special considerations are required to explain their behavior. In recent studies, the plant tests were performed at Bougainville and batch tests were carried out at the Utah Comninution Center. In all tests power measurements were made and several levels of energy input to grinding were evaluated. Also, tracer tests were performed for mill residence time determination. The performance of Bougainville's 5.5 x 6.4 m mill has been very successfully predicted by population balance methods. The prediction errors are only about 1% on product size distribution and 4% on power with a mill volume scale-up of 3790 to 1. It is significant that this approach will reduce the risk of failure in large mill design that has been recognized in traditional methods.

Jan 1, 1987

By M. R. Peterson

The U.S. Bureau of Mines (USBM) is investigating alternative methods to strip metal-loaded solvent extractants. Hydrolytic, precipitation, and hydrogen pressure stripping all recover metal or metal salts directly from the organic solvent extractant. Pure metals, metallic oxides, or metal salts can be formed, allowing direct production of value-added products. Aspects affecting commercial application are emphasized, including metal recovery from actual ore leach solutions, particle size control, organic modifier and diluent effects on stripping and metal recovery efficiencies, metal grade, seed addition, mixing intensity, recycling efficiency, and reactor plating. Metal separations from copper ore leach solutions and complex waste leach solutions were examined.

Jan 1, 1995

By W. C. Morgan

The Federal Surface Mining Law enacted in 1978 is now being translated into regulations which must be followed in future coal mining. Substantial change to mining procedures is required to maintain stricter air and water control while mining and to return the mined out land to equal or better use than before. These changes do not come easy; and in most cases, they create a substantial additional cost. Based on field observations and mining studies, Caterpillar has been making suggestions on the use of their types of equipment to conform to the new standards at the least cost. This paper will be a brief review of some of the overburden stripping and reclamation methods suggested by Caterpillar. A production and cost comparison of dragline, scraper/dozer and truck, loader systems in 20 to 150 ft. Overburden conditions illustrates potential cost savings using mobile equipment.

Jan 1, 1980

By E. Kaya

Investigations of fine grinding of bituminous coal in a laboratory-scale pulverizer are described. The results indicate essentially "normal" breakage behavior at relatively coarse sizes (greater than about 20 µm) but show clear evidence for re-agglomeration in the fine size range (less than about 10 µm). A simplified population balance model for simultaneous growth and breakage has been formulated. Breakage rates and breakage distributions are assumed to follow the patterns typically observed in simple grinding systems. It is recognized, however, that solid particles and agglomerates may exhibit different breakage behavior. Agglomeration rates are assumed to be determined by contact probability, i.e. by the relative numbers of interacting particles. Based on comparisons of model simulations and experimental data, it appears that agglomerate re-breakage rates and fragment size distributions are quite different from those for solid particles. The result is that product size passes through a minimum and then increases with time as agglomeration begins to dominate.

Jan 1, 1996