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By William D. Mayercheck

Beginning in 1974, the Bureau of Mines, U.S. Department of the Interior, sponsored R & D efforts related to further development and use of continuous face haulage in underground coal mines (Cowan, 1975). The U.S. Department of Energy continued this effort as of October 1977. This paper represents an update of an article previously published in Mining Engineering magazine (Mayercheck, 1979). Development progress is summarized for a variety of prototype systems or components now being built, surface tested, or tried underground.

Jan 1, 1981

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-cu-yd) transit mixer and a shotcrete spray boon carrier, is used by a two-man crew to transport and place up to 25 m3 (32 cu-yd) of steel fiber reinforced, dry, silica fume shotcrete per 11-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control are performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1992

By J. G. Groppo

A beneficiation process has been developed to provide selective separation of unburned carbon from high loss-of-ignition (LOI)fly ash. Using froth flotation to achieve selective separations requires long residence times and high reagent costs. A proprietary reagent system has been developed to address these limitations. Based on the results obtained from laboratory and pilot-scale investigations, a flowsheet design has been developed to produce two distinct usable products from class F fly ash — low LOI ash and a high-carbon product suit-able for reburning or further upgrading.

Jan 1, 1996

By Michael Clar

Total suspended solids (TSS), generally referred to simply as sediment, is one of the four major parameters of water pollution associated with surface mining activities. The other three para¬meters are iron, manganese and pH. Currently the Environmental Protection Agency (EPA) is in the process of developing and implement¬ing effluent limitations for these pollutants pursuant to section 301 of the Federal Water Pollution Control Act Amendments of 1972, 33 USC 1811.1 To date, effluent guidelines for existing point sources have been published, and guidelines for new sources are forthcoming. The effluent limits which have already been developed for TSS have been subjected to some controversy.1 Some industry spokesmen have indicated that they may be unable to meet these effluent limitation guidelines for TSS. The industry claims that in certain areas the suggested limit is unattainable since high suspended solid loads already exist in streams due to numerous and various sources of nonpoint pollution which include agriculture, silviculture and urban construction for which no TSS effluent limits have been set. An opposite viewpoint asserts that the TSS limitations are too lenient since permit data from the Regions (U.S. EPA Regions) indicates present compliance for several companies under more stringent TSS limits. The experience at the Centralia mine in Washington is one example.2

Jan 1, 1977

By T. O. Llewellyn

The Bureau of Mines, U.S. Department of the Interior, conducted studies to recover phosphate from four dolomitic southern Florida deposits not currently mined. The samples contained 5.8 to 10.2 percent P205 and 1.7 to 1.8 percent MgO. Chemical analyses of sized fractions indicated that no pebble concentrate (plus 1.2 mm) could be produced from these samples. A scheme was developed that consisted of desliming, grinding, scrubbing, and redesliming the ore to produce a flotation feed. Conventional one-step fatty acid-fuel oil batch flotation tests on the samples resulted in concentrates containing 29.0 to 31.3 percent P205 at flotation recoveries ranging from 72.4 to 96.1 percent of the flotation feed. The MgO content of the concentrates ranged from 0.47 to 1.36 percent. Continuous flotation of the Manatee No. 2 sample indicated that commercial-grade phosphate concentrates analyzing 31.3 percent P205 and 0.55 percent MgO could be produced with a flotation recovery of 89.9 percent. The MgO content of concentrates obtained from the Manatee No. I and Hardee samples was 1.20 to 1.36 percent, respectively. Leaching with aqueous SO2 reduced the MgO content of these phosphate concentrates to 0.5 and 0.8 percent, but with a concomitant loss in phosphate recovery.

Jan 1, 1983

By R. A. Jankowsi, S. K. Ruggieri

Airborne respirable dust levels on longwalls can be reduced if operators approach the dust control problem in a logical and fundamental manner. This can be accomplished through the proper application and continued use of effective dust control techniques. The Bureau of Mines is currently assessing the effectiveness of longwall dust control techniques in use today to provide mine operators with guidelines for selecting the most appropriate control technology. This paper presents a fundamental approach to the problem of shearer dust control. Three dust control techniques to be discussed are: deep cutting/increased pick penetration for reducing the amount of respirable dust generated; drum water sprays/improved water supply system to suppress the amount of airborne respirable dust; and improved external water spray system, the "shearer-clearer," to push the dust close to the face. The techniques have been evaluated in field trials and have been shown to be both practical and effective in applications to control shearer generated dust.

Jan 6, 1985

By A. G. Sciulli, G. P. Ballock, K. K. Wu

Waste disposal underground is the most effective method when viewed from an environmental aspect. As costs of other methods of disposal continue to escalate, the cost effectiveness of underground disposal during the mining cycle becomes increasingly attractive. The use of concrete for sealing abandoned mines has proved to be suspect when associated with a relatively incompetent adjacent strata due to its shrinkage characteristics. Complete failure of the plug has been known to occur in some instances. A more effective, cost competitive seal can be obtained using pneumatically stowed material and incorporating a polyurethane grout, which has greater adhesion characteristics than concrete. Injection of the surrounding strata and of the stowed material helps to ensure an impervious barrier and prevent the plug from moving when subject to high pressure heads. When properly placed, impervious seals cause the old workings to flood, raise the mine pool level, and thus eventually eliminate the potential for oxidation, which is the primary cause of acidity in the water.

Jan 11, 1986

Diesel powered machines are doing some specific operations in the cyclic order required by the technical process. The dynamics of this process in certain conditions has an essential influence on environmental health conditions in the working area. The main purpose of this paper is to show, using computer simulation, how the movement (dynamic) of diesel vehicles effects environmental health standards and also how to determine the required air quantity for ventilation.

Jan 6, 1985

By A. K. Bhasin

The movement of solid particles in a liquid represents an area of interest in many fields of science and technology. Knowledge of the behavior and characteristics of solid-liquid suspensions is of great importance to many areas of mineral processing. In order to characterize a solid-liquid system, the following factors must usually be considered: a) density of the liquid b) rheological properties of the liquid c) density of the solid particle d) size and shape of the solid particle e) volume fraction of solid particles f) relative motion of solid particles and liquid phase Other variables such as the effect of the containing vessel walls, Brownian movement, inter-particle friction, fluid slip and electrostatic effects, are important in special circumstances. Thus it is evident that a complete theoretical treatment is not possible covering all situations. Studies of the kinematic behavior of solid particles in a liquid have been approached by two methods: 1) Assessing the movement of a single particle and extrapolating to a multi-particle system; 2) Modifying the continuum mechanics of single-phase liquids in such a way as to account for the presence of solid particles. The first approach in general utilizes the method of particle mechanics. Extension to a multi-particle system gives rise to very complicated mathematical computation. The creeping motion equations do, however, furnish a practical, useful basis for achieving a uniform treatment and a better understanding of the phenomena. This approach is useful in the study of sedimentation and hindered settling processes.

Jan 1, 1971

By Ronald F. Ayers

The study upon which this paper is based was completed by Battelle's Columbus Laboratories for the U.S. Army Corps of Engineers in 1974. It is but part of an overall effort by the Corps to evaluate the costs and benefits to the nation of waterway improvements. This study is primarily concerned with future coal markets for production from those counties near the Wabash River in the heart of the Eastern Interior Province. An objective here is to consider a most pessimistic energy (and hence, coal) demand for planning purposes.

Jan 1, 1976

By Wei Luo

Nickeliferous laterites were characterized by particle size analysis, X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR) spectroscopy and thermal analysis. Results showed that the laterites consist mainly of nickel-substituted lizardite with cobble-like morphology and traces amounts of magnetite and phlogopite. As fluoride ions can react with silicon in the lizardite crystal structure and form metal-fluoride complexes, as well as increase the equilibrium constant of the lizardite dissolution in acid solution dramatically, the addition of minor fluoride salts (0.2wt.% NaF) gave a markedly enhanced metal extraction rate (Ni 81.7% and Co 52.3%) under the experi-mental conditions of particle size d50= 25 µm, 10% (v/v) H2SO4, reaction time 2 h, reaction temperature 90°C, liquid-to-solid ratio 3 mL g-1 and stirring at 500 rpm compared with H2SO4 alone (Ni 69.6% and Co 30.8%).

Jan 1, 2010

By M. S. Celik

Beneficiation of boron minerals by flotation with well defined systems has been very little investigated in the literature. The difficulty arises from the fact that boron minerals cover a spectrum of solubilities. Colemanite, a calcium containing relatively insoluble boron mineral, and borax, a highly soluble boron mineral have been used to exemplify the flotation of boron minerals. The floatability of both minerals using sodium dodecylsulfonate and dodecylamine hydrochloride exhibits considerable differences in their response to flotation. This has been ascribed to variations in the solubilities 0f boron minerals and the presence of the cations in the lattice structure. Flotation tests along with zeta potential measurements are used to elucidate the mechanisms involved in the flotation of boron minerals.

Jan 1, 1992

By Samuel Polinsky, Lawrence W. Bierman, Wayne Perkins

[A column float beneficiation plant using 9, 8.5 foot diameter, cells was constructed by the Simplot Company and the Smoky Canyon Facility in the fall of 1986 and has been in operation since May of 1987. The float beneficiation process was developed jointly by the Simplot Company and the Bureau of Mines (Salt Lake City, Utah) which incorporates the Bureau's bubble generator design and chemistry system based around the reverse float technology, (Albany Bureau of Mines, Application of Carbonate-Silica Flotation Techniques to Western Phosphate Materials, Rule, Dallenbach , Larsen, RI8728, 1982) . This chemistry has been modified by Simplot in both patented and unpatented improvements. The objective of the beneficiation process was to reducethe A1203 content in the overall pipeline concentrate by 0.2 wt z. Therefore, a process stream was identified in the mill circuit which provided an opportunity to isolate and treat 1100 tons per day of poor quality phosphate concentrates The process allows recovery of approximately 15% of the mill concentrates, otherwise unsuitable for fertilizer production. The alternative would have been to waste this ore. Wasting would have resulted in considerable ore loss, increased mining costs and required additional products grinding. ]

Jan 1, 1989

By Kendall Y. Onstott

The paper presents the results of a plant test using WEMCO 1 + 1 enclosed flotation machines for inert gas (nitrogen) flotation of by-product molybdenite from copper sulfide concentrate. Copper depressant consumption in the rougher flotation stage was reduced by 68% as reagent consuming oxygen was removed from the flotation air. Unlike other nitrogen flotation systems used in the industry, nitrogen is recovered above the flotation cells and from froth in tails and concentrate streams and recycled, resulting in minimal nitrogen makeup requirement.

Jan 1, 1984

By Theophilus Mensah, Kwame Awuah-Offei

Engineers face significant challenges when determining what geometry provides the most profitable and safe stope for extraction. Several techniques and optimization algorithms have been developed in recent years, but most fail to find optimal solutions because they are heuristic or LP-based without efficient geometric constraints. This paper presents a two-dimensional binary linear programming (BLP) model for determining the optimal combination of blocks in a stope that maximizes the economic value of the layout of stopes for a sublevel deposit. The work draws from Queyranne and Wolsey’s (2017 & 2018) formulations of tight constraints for bounded up/down times in production planning problems to formulate novel and efficient geometric constraints along with geotechnical and grade constraints for the BLP stope layout optimization problem. Results from the model indicate that it is possible to formulate efficient shape constraints in LP-based approaches. The model used for the numerical example contained 144 valuable blocks out of 774 blocks, which translates into an economic value of $53.21M. The BLP model selected 60 valuable blocks and 13 waste blocks that met all constraints translating into a maximum economic value of $34.4M in 1.83 hours within a gap tolerance of 0.00%.

Jun 25, 2023

By H. Sevim

This paper identifies and formulates the probabilistic nature of underground coal face operations using the Semi-Markovian theory. Through this theory the probability of coal flow from a face is obtained for any given time t of a shift. These probabilities are used for determining the capacity and operating policy of a surge tank located at the shaft bottom.

Jan 1, 1984

By Jerry C. Tien

Without a doubt, the scope of China?s coal boom has been nonstop. Despite the world economic slowdown, China?s year-on-year gross domestic product (GDP) jumped 10.3 percent year-on-year in 2010, boosted by a faster than expected 9.8 percent expansion in the fourth [ ] quarter. And, the first quarter of 2011 expanded another 9.7 percent. According to a frequently cited statistic, the country is building two mid-sized coal plants each week. This amounts to a yearly increase equivalent to the entire power grid in the United Kingdom. China?s coal production was doubled in the last 10 years, from 1.044 Gt (1.15 billion st) in 1999 to 3.2 Gt (3.52 billion st) in 2010. This is 3.2 times the U.S. production (986 Mt or 1.085 billion st) and nearly half (46.3 percent) of the world?s total coal production (6.91 Gt or 7.6 billion st). This rapid increase of demand for coal has made China the world?s largest coal importer in 2009. With the economic situation improving, this trend is expected to continue.

Jan 1, 2011

By A. T. Yu, K. A. Young, Ronald M. Hays, Sanford Terry, D. R. Campbell, J. K. Lovrien, W. L. Price, C. W. Matthews, W. R. van Slyke, S. P. Cole

Storage and transport systems are essential for mineral processing. Section 10 includes systems for storage and transport of dry bulk materials, slurries, and water necessary for operation of mineral pro¬cessing plants. All aspects of these systems are presented, including material characteristics; dry material placement in and reclamation from storage stockpiles and bins; dry material conveyance; hydraulics (liquid flow and pumping); slurry characteristics; slurry storage and reclaim, slurry flow (distributors, launders, and pipes), and pumping; water (primary and secondary process, reclaimed, fire, cooling, and domestic) supply, transport, and storage; equipment selection and sizing; power transmission; controls; and health and safety. The mate¬rials considered include crude ore; process and other water supplies; initial, intermediate; and final in-plant materials; finished materials; and tailings and other waste products. Section 10 is a compilation of practical operating data for engineers, technicians, and plant opera¬tors. For the design of mineral processing plants, including selection and sizing of equipment, the design engineer should consult with equipment manufacturers, suppliers, engineering firms, and plant op¬erators with specialized experience in particular materials handling methods. When unusual conditions are encountered, actual pilot or full scale testing may be required to insure adequate design. Operation of mineral processing plants is dependent on the proper engineering and construction of storage and transport systems for dry bulk materials, slurries, and water. It is obvious that processing plants cannot produce the required quantities of semifinished and finished products unless these material can be transported adequately to, through, within, and from the plant. Costs of storage and transport systems may exceed 50% of the total capital and/or operating costs. Considerable attention must be given to the design, layout, and engineering of these systems. These systems are interrelated with the mineral processing method and it is necessary to determine the best combination of mineral processing method and storage and transport systems. Storage and transport systems perform a major supportive func¬tion to mineral processing. The final selection of these systems depends on the final selection of the processing method and related systems (environmental control, tailings and waste disposal, etc.). The process¬ing method determines the characteristics of materials to be stored and transported; distances, elevations, flow rates for transport; and storage requirements. Flowsheet After selection of the processing method and related systems, a flowsheet must be developed. This flowsheet should indicate produc¬tion rate, percent solids or moisture, and specific gravity for all initial, intermediate, and final products or product flow streams. It also may be necessary to know the size analysis, chemical analysis, abrasiveness, and other physical characteristics of various product flow streams. The flowsheet provides basic information for plant layout, storage requirements, and selection and sizing of process and transport equip¬ment. Storage and transport systems often function improperly be¬ cause of inadequate flowsheet data or process revisions, resulting in improper equipment selection and sizing. Further details on plant design are presented in Section 33. After selection and sizing of process equipment, it is necessary to select the type of material transport equipment to be used for in¬plant materials handling as well as crude ore, tailings, and final prod¬ucts. The storage and/or surge requirements, including capacity and location, then are determined. Storage and/or surge capacity is neces¬sary for leveling production rate fluctuations due to variations in material characteristics; production scheduling; equipment mismatch¬ing, failure, or breakdown; and scheduled maintenance downtime. Variations in ore grindability will cause fluctuations in throughput or production rate for grinding mills and variations in ore grade will cause fluctuations in production rate for concentrating equipment. Variations in material moisture content and percent solids can have serious effects on the capacity of material transport equipment. In some cases, a blending system may be desirable or necessary to reduce variations and to obtain uniform production and/or metallurgy. Storage capacity often is needed because of different production schedules for various phases of the mining and mineral processing complex. As an example, the mine and coarse crushing plant may operate on a one- or two-shift-per-day schedule while the fine crushing plant and concentrator on a three-shift-per-day schedule. This would require storage between the coarse and fine crushing plants. Another example would be load-out storage where unit trains are used to haul concentrate or final products. The concentrator could be operated on a three-shift-per-day schedule while only I to 2 hr may be scheduled for unit train loading. This would require adequate load-out storage so that the concentrator can be operated continuously. Process equipment with mismatched capacities requires storage or surge capacity between the mismatched equipment to achieve oper¬ating efficiency. As an example, the fine crushers may have greater capacity than the rod mills. Storage between the fine crushers and the rod mills permits both the crushers and rod mills to be operated at optimum capacity with the crushers actually operating or running a lesser number of hours per day. Mismatched capacities for process and transport equipment also may require storage or surge capacity. Mismatching of equipment capacities most often occurs because of the difficulty in equipment sizing. Thus, the design engineer must anticipate where in the flowsheet these mismatching capacities are likely to occur while making every effort to assure that equipment is selected and sized properly. Equipment breakdown can cause major operating difficulties and lost production. These breakdowns can be reduced with adequate scheduled maintenance. Lost production due to nonscheduled down¬time caused by equipment breakdown can be reduced further by standby equipment and storage and/or surge capacity ahead of essen¬tial mechanical and electrical equipment. As an example, standby pumps and conveyors often are available as part of the in-plant trans¬port system. Storage and/or surge bins and tanks often serve dual functions, such as dewatering, mixing, and smoothing production rate fluctuations.

Jan 1, 1985

By M. J. Virnig, B. D. Boley, G. A. Wolfe, J. M. W. Mackenzie

A flowsheet for the recovery of nickel and cobalt from laterite ores has been developed which involves acid leaching followed by hydroxide precipitation of the metal values and then releaching of the hydroxide cake with ammonia. Investigations of the chemistry of extraction of nickel by LIX® 84-I and a developmental reagent, XI-84-IT, along with the physical properties of the organic phases are described. Based on these investigations, suggestions with regard to design of a solvent extraction plant and operating conditions are made.

Jan 1, 1999

By P. C. Kapur

For mineral processing spirals, mathematical force equilibrium models are sought to extend the spiral performance envelop. In Part 1 of this report, a complete geometric description of the helical spiral and its trough or channel contour is provided. The secondary circulatory fluid motion in the transverse direction that develops when water flows down a tightly turning curvilinear path and its implications for gravity separation are discussed. Different forces that act on the particle during its passage through the spiral are enumerated and quantified for a better appreciation of their relative contributions and roles in the separation process. Three force equilibrium models from the hydrology literature on sed iment transport are employed to simulate a typical spiral. While the results are promising in that the models mimic the broad performance characteristics of the spiral, what is needed is a more general spiral model taking explicit cognizance of the missing components essential to the spiral description. These are such components as centrifugal force and the steep tangential slope of the channel deck. Results of this latter exercise are deferred to Part 2.

Jan 1, 1996