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By Katherine Hynard, Colin Eustace

Suboptimal decisions introduced during the mine planning process are generally a consequence of both a myopic view of planning objectives as well as time and resources available to convert longer-term plans into execution plans. Erosion of strategic mine plan value in conversion to execution plans is likely to amount to billions of dollars each year. When integrated with operations data feeds, simulation and optimization tools can be used to preserve the value in the strategic mine plan. Optimization models are capable of both automating production of execution plans and improving performance. This reduces the manual burden of revising plans while improving alignment with long-term production objectives. Simulation models can also support the process of developing effective execution plans by providing forward visibility of mine operations performance. They can also be used to test the robustness of optimized execution plans and response to operational variability and disturbances.

May 1, 2025

By R. Vance, C. Cho, N. Mardi, Z. Qian, K. Prisbrey

One problem with the application of neural networks to the multivariable control of mineral and extractive processes is determining whether and how to use them. The objective of this investigation was to compare neural network control to more conventional strategies and to determine if there are any advantages in using neural network control in terms of set-point tracking, rise time, settling time, disturbance rejection and other criteria. The procedure involved developing neural network controllers using both historical plant data and simulation models. Various control patterns were tried, including both inverse and direct neural network plant models. These were compared to state space controllers that are, by nature, linear. For grinding and leaching circuits, a nonlinear neural network-based model predictive control strategy was superior to a state space-based linear quadratic gaussian controller. The investigation pointed out the importance of incorporating state space into neural networks by making them recurrent, i.e., feeding certain output state variables into input nodes in the neural network. It was concluded that neural network controllers can have better disturbance rejection, set-point tracking, rise time, settling time and lower set-point overshoot, and it was also concluded that neural network controllers can be more reliable and easy to implement in complex, multivariable plants.

Jan 1, 1998

By Hans Breuer

The new regulations for the bituminous coal mining industry, issued by the mining authorities of the Federal Republic of Germany, are aimed at reducing to a feasible minimum any development of the coal workers pneumoconiosis (CWP) by lowering the admissible dust exposure of mine workers. Additional and improved measures of dust suppression and job assignment control *) are required for the purpose In this connection two basically different demands are placed on dust measurements: As far as dust suppression is concerned, the causes of dust development and the effectiveness of methods applied to reduce dust concentrations have to be identified, whereas with regard to the control of job assignment, the dust exposure of mine workers has to be depermined. Demands placed on dust measurements -- specifically for determining dust exposure -- are liable to become more severe since the threshold limit values were considerably reduced in these last years and since any additional dust suppression measures as well as a purposeful job assignment to certain mine workers are dependent on relevant measuring data. Therefore, research work has been carried out with the objective of measuring and evaluating, in terms of their effect (i. e. their incidence on the development of a CWP), size distribution, concentration, and specific noxiousness of any prevailing dust conditions.

Jan 1, 1980

By D. Gärtner, A. Oster

"""Operational excellence"" provides a sound foundation for RWE Power AG's three strategic pillars (innovation, expansion and organic growth). The maintenance and development of operational excellence in lignite mining operations at RWE Power is supported by the Continuous Improvement Process (CIP) ""immer:besser"" (getting better). Obtaining cost reductions with the aid of the CIP as a kind of value-adding self-renewal process to ensure competitive lignite mining operations and lignite-based electricity generation forms the basis for further increases in profitability and growth. Since the beginning of the 1990s, RWE Power has carried out a multitude of re-engineering projects focusing on the efficient shaping of processes with the assistance of external consultants to enable the Company to cope with the considerable need for change by swiftly implementing major efficiency levers. These also include the required adaptation and development of the organization. Since 2004, the Continuous Opencast Mine Improvement Process (""KVT"") has enabled the mines to tap significant cost reduction potential by virtue of their own strength. But there is another issue that has come into focus: the development of performance enhancement options. In 2006, the ""KVT"" process, piloted in the opencast mines, was included in the RWE Power-wide immer:besser (i:b) programme (Figure 1)."

Jan 1, 2011

By J. L. Huiatt

The U.S. Bureau of Mines and Great Salt Lake Minerals and Chemical Corp. developed a froth flotation process for concentrating potassium salts from Great Salt Lake solar evaporites containing about 5 percent K. The crude evaporites, which were predominately halite (NaCl) with smaller amounts of kainite (KCl.MgSO4.2.7H20) and schoenite (K2SO4MgSO4.6H20), were conditioned in a saturated brine solution, thus converting nonfloatable kainite to the floatable mineral schoenite. Schoenite was then selectively floated with a medium-molecular weight fatty acid. Continuous small-scale pilot plant testing indicated that 80 percent of the potassium could be recovered from the crude evaporites in flotation concentrates assaying about 11 percent K.

Jan 1, 1975

By V. J. Hucka

A 0.5 m (20 in) diameter high pressure natural gas pipeline crosses over a coal mine located in Central Utah. Ground movement induced by the mining operation could possibly place excessive strain on the pipeline causing it to rupture. The mining operation extracts coal from two seams using the room and pillar method. The seams are situated one on top of the other and both lie directly under the pipeline. At present, only the upper seam is being mined beneath the pipeline. However, in the future, the mining operation of the lower seam will also affect the pipeline. As would be expected, mining of both coal seams causes surface subsidence. This is especially true when the pillars are extracted during retreat.

Jan 1, 1983

By Paul D. Bybee

The Freeport Sulphur Company operates four sulphur mines in the coastal marsh area-03 South Louisiana. Employing the Frasch process of mining, approximately 13-million gallons of water per day is heated to a mining temperature of 325°F and is injected into the sulphur bearing formations of the four mines. A volume of cold waste water, roughly equal to the Input, is removed from the formations and presents a disposal problem. Two additional mines are currently being developed and will increase the disposal volume by an additional 5-million gallons per day. Although these properties are in a relatively small area, geographically speaking, as shown in Figure 1, they each represent a separate disposal problem with the treatment methods designed for the individual mine.

Jan 1, 1959

By Wescomb R. Jones

The United States is the world's largest producer of hydrofluoric acid (HF), with its 1971 output of 317,000 short tons representing about 40 percent of the estimated Free World production. U. S. production has increased over five fold in the past 20 years, with a growth rate of about 7 percent per year between 1960 and 1970. However, the growth rate to 1977 is expected to be less than 5 percent per year, due primarily to a reduced rate of growth in requirements by the aluminum industry and an expected increase in imports from Canada and Mexico. This discussion will include our analyses of the consumption pattern for HF in 1972 and the factors influencing the demand forecast for 1977.

Jan 1, 1973

By S. C. Sun

The grinding of coals for coal preparation has been studied extensively by previous investigators, but no similar work has been done on coal lithotypes (l-4). However, the different natural breakage characteristics of coal lithotypes have been recognized and utilized by the coal industry (5,6) to develop the Longway Burstlein process (7) for the concentration of macerals(8). The specific objective of this research was to determine the relative grindability of lithotypes, obtained from both anthracite and bituminous coals. An attempt was made to relate the findings, wherever possible, to the chemical and physical properties of the tested lithotypes. Another aspect of this research was to ascertain the size distribution and grindability of lithotypes ground at a various number of revolutions in a Hardgrove mill.

Jan 1, 1970

By J. R. Batista

Leachates from gold heap-leaching mines contain selenium concentrations as high as 2 mg/L. Previous studies report satisfactory selenium adsorption by activated alumina when using relatively "clean" drinking waters. However, the findings of these studies cannot be directly applied to the treatment of mine leachate where other ions compete for the alumina adsorption sites. This study evaluated the adsorption of selenium from a mine leachate to develop design parameters for full-scale activated alumina processes. The study revealed that 68% of the selenium in the leachate could be removed by alumina at pH > 5.0. Silica adversely affected the selenium adsorption capacity. At pH values < 4, silica was poorly adsorbed by alumina and selenium adsorption was improved.

Jan 1, 1994

By Frank W. Bowdish

Studies of sulfidization and flotation of chrysocolla involving the use of pH and sulfide ion instruments, a Zeta meter, microflotation techniques, and sensitive determinations of adsorbed sulfur have given new insight into the mechanism of the process. Factors that affect the recovery of sulfidized chrysocolla by flotation appear to be the pH at which it is sulfidized, and certain alterations of the surface that occur during aging after sulfidization. Such aging results in increased recoveries. The surface charge, as measured by electrophoretic mobility, of chrysocolla shows an unexpected negative increase as pH values are changed from 6.0 to about 4.5, and this appears to be correlated with increasing sulfur adsorption and flotation recovery over the same or even wider pH ranges.

Jan 1, 1970

By I. M. Konduri

Theoretical investigation and laboratory experimentation have shown a great potential for jet fan ventilation in mines. Jet fans, also called induction fans due to the induction effect of the fluid jet to ventilate headings, may have particular application in remote-controlled production operations. This paper summarizes ongoing research using a scaled laboratory model. The model uses water as a fluid medium and simulates a typical 25m long heading of 1.5mx6m cross-section. The effects of various nozzle positions and designs have been investigated by using still photography as a tool for flow visualization. It is also found that the use of jets in combination with line curtains has enhanced the overall ventilating effect in the model entry.

Jan 1, 1996

By N. R. Sainath

This paper discusses the results of a laboratory investigation carried out to study the microscale flow characteristics of copper ores and the variation in flow behavior resulting from flow of leach solution. Fractures in 1.5 and 4 inch diameter cores were mapped by visual inspection. The cores were stressed in a triaxial stress field representative of in situ conditions. The permeability of the samples to water was then estimated. The samples were exposed to 20 g/l sulfuric acid and the experiment repeated. The Permeability of unleached samples ranges from 10-1 to 10-19 m2 and it increases as leaching progresses. The porosity variation and the rate of recovery of copper from the specimen during leaching were also studied.

Jan 1, 1991

By K. M. Belingheri, M. E. Smith

Pinson Mining Co. operates a conventional mill and two heap leach operations in north-central Nevada. The latest of these heap leach operations, the Preble project, is a low-grade, low-tonnage property made profitable through several innovative capital reduction techniques. Rapid return on investment was a prime factor in design. To facilitate this, fast-track design and construction techniques were employed. The project is a seasonal 1.5 kt/d (1 700 stpd) crush/agglomerate heap leach plant using both clay and plastic leach pads. Construction and startup were achieved through cooperative arrangements between local contractors and in-house construction personnel, with few items put out to bid. An interactive approach to design minimized lost time and construction costs.

Jan 1, 1987

By B. E. Dindsale, P. B. Altringer, R. H. Lien

The Bureau cf Mines, U.S. Department of the Intericr, is investigating biolcgical and chemical deccntaminaticn of cyanide- containing leachates and residues. Biolcgical cyanide cxidaticn, using bacteria isolated from a precious metals tailings pond, destroyed >85 pct of the cyanide in several prccessing solutions containing up tc 280 ppm CN. Reaction time varied from about 4.5 hr in a trickling reactor using quartz as a bacterial substrate to 2 mo in unagitated, covered flasks. Chemical techniques were used to destroy the remaining complexed cyanide down to 1 ppm. Exploratory tests were also conducted using spent ore from heap leach operations as the bacterial substrate to determine if biological cyanide oxidation could be used to destroy the residual cyanide in spent heaps.

Jan 1, 1991

By Ken J. Fair, Vicken H. Aprahamian, Gus Van Weert

A consortium of Canadian mining companies, engineering firms and the Ontario Government has supported Hydrochem&apos;s efforts in the last year to design and cost a 10 tpd NITROX PROCESS® demonstration plant. A 5 kg per hour mini plant was installed at the Hydrochem facilities in Brampton, Ontario. This paper describes design testwork on Dickenson Mines arsenopyrite concentrate and application of the findings to the demonstration plant flowsheet. The control of nitrates in discard solids and stack gases is discussed in detail. Nitric acid oxidation of arsenopyrite results in significant ele- mental sulphur formation, enough for it to be detrimental to sub- sequent cyanidation. Flowsheet variations aimed at dealing with this process characteristic are discussed and testwork results on one option (hot liming) are described.

Jan 1, 1988

By Th. Petropulos

The Zn-Ag-Pb mineralization zone near Molai (Greece) was explored by more, than 60 drillholes. Promising results led to the decision of additional drillholes in order to confirm the expected spatial extension of the deposit. A multiobjective approach is described which optimizes the location of a set of 5 additional drillholes. The decision is based on estimation errors for grade, thickness and depth of the main ore bearing layer, with respect to cut-off values for grade and thickness. The linear combination of these variables defines a favorability index which is used for mapping optimal drillhole locations. The map shows several clusters of favorable cells. A declustrering algorithm is used to select a representative cell for drilling in each cluster.

Jan 1, 1989

By Haydn H. Murray, Fred G. Heivilin

The "Hormite Group" was proposed for palygorskite (attapulgite) and sepiolite for their complex magnesium silicate composition and elongate crystals (Martin-Vivaldi and Robertson, 1971). These minerals occur in close association with each other and more complex structural variations may exist (Bailey, 1972). In 1862 Savchenkov used the name palygorskite to describe a mineral from the Palygorsk locality (Hay, 1975), near the Ural Mountains. Ovecharenko and Kukovsky (1984) mention that when mountain leather deposits were prospected in the Palygorsk Division mine it was assumed this unusual mineral was a variety of asbestos. Early mineralogists used the terms "mountain cork" or "mountain leather" when referring to palygorskite. Robertson (1986) mentions that it appears palygorskite was known since Theophrastus&apos; time, ca. 314 BC. J. de Lapparent used "attapulgite" for clays from Attapulgus, GA, and Mormoiron, France, because he thought them different from palygorskite, but the two types were proved to be the same (Bailey et al., 1971). The name attapulgite is still used for the Florida and Georgia deposits when the crystal length to diameter ratio does not exceed 10:1(Merkl, 1989). Georgia palygorskite clays are of much shorter length compared to classic palygorskite. In 1847 Glocker first used the name sepiolite which was called "Meerschaum" by Werner (1788) and Hauy (1801) namedit "Ecume de Mer." Brochant (1802) described low density and white magnesium silicates adding the name Talcum Plasticum and Ecume de Mer. In the Meigs-Attapulgus-Quincy district palygorskite (attapulgite) commonly occurs in two distinct forms referred to as short length palygorskite (Meigs Member) and long length palygorskite (Dogtown Member) (Merkl, 1989). Long length palygorskite crystals (> 10 pm) are rarely observed in the Meigs and Dogtown Members, but when present are in association with dolomite crystals. The short length form is usually less than 2 pm in length and has a low magnesium content whereas the long length form has a high magnesium content and a length greater than 2 pm. The distinctions in morphology are not only important because of the relationship to the origin of the deposits, but also in relation to activity in causing membranolytic activity related to data on palygorskite samples from 9 locations ranging from relatively inert to active in work reported by Nolan et al. (1989). The > 10 pm lengths amounted to only 51 of 17,401 fibers sized. The shortest lengths (< 0.5 pm) were relatively inert. This study pointed out that surface activity, morphology, and chemical differences may be distinctly different within the definition of palygorskite, or for that matter for any individual mineral so that health and other properties must be measured because the name alone does not necessarily indicate uniformity. Palygorskite (attapulgite) fuller&apos;s earth was first sold for drilling mud in 1941. The market for this use expanded slowly and has maintained a level of 7 to 10% of the total US production during the last few years. Most of the fuller&apos;s earth sold for drilling mud comes from the southern part of the Meigs-Attapulgus-Quincy district of Georgia and Florida. Palygorskite clays produced in this area are superior to most other fuller&apos;s earth for mud used in drilling salt formations, but because of high water loss, they are inferior to bentonite where the rocks drilled contain no saltwater. According to Oulton (1965), more than 90 different grades of fuller&apos;s earth are produced. Some of these grades are used for pharmaceuticals designed to absorb toxins, bacteria, and alkaloids; for treatment of dysentery; for purifying water and dry cleaning fluids, dry cleaning powders and granules; for the manufacture of NCR (no carbon required) multiple copy paper; for the manufacture of wallpaper; and as extenders or fillers for plastic, paint, and putty. Fuller&apos;s earth mined near Ellenton, FL, was used for making lightweight aggregates for the construction of concrete barges during World War I1 (Calver, 1957). Still other uses of fuller&apos;s earth and its suitability for uses in new products are outlined by Haden, Jr., and Schwint (1967), Haden, Jr., (1972), and Haas (1970). One special use of fuller&apos;s earth is as a carrier of platinum catalysts that are made in the United Kingdom from sepiolite clays mined in Spain. Other uses of sepiolite fuller&apos;s earth (Chambers, 1959) are similar to those of the palygorskite (attapulgite) type mined in the United States.

Jan 1, 1994

By T. W. Healy, W. J. Trahar

INTRODUCTION The flotation of minerals from their ores in flotation cells involves understanding many chemical and physical processes ranging from electronic events in the bulk mineral and in the mineral surface regime. molecular events at interfaces, the statics and dynamics of thinning and rupture of microscopic to molecular intefacial films, the fluid mechanics of bubble- particle events, the dynamics of air-water-solid colloid states in a flotation machine, etc. etc. D.W. Fuerstenau, whom we honour in this symposium has made unique contributions to many of these diverse physico-chemical and technological sub-processes. The present paper is concerned with a number of observations of the behaviour of minerals in flotation cells and the surface science of some mineral sulfide-water systems. We do not intend to be comprehensive in our analysis, but rather to highlight the challenges that face the scientific masochist who chooses to understand "froth flotationn. In what follows, emphasis is placed quite deliberately on technologically relevant, dynamic or realistic flotation processes i.e. the recovery in a froth of a given sulfide mineral particle of a given size and history from synthetic or actual ores in a flotation cell. The paper also attempts to use the understanding that is emerging from the area of photoelectrochemistry of colloidal

Jan 1, 1989

By S. E. Phillipson, S. Romberger

The Late Miocene San Cristobal Ag-Zn-Pb deposit represents syngenetic and epigenetic mineralization with low- and high-sulfidation characteristics. The geology of the deposit is characterized by barren dacitic ring fracture domes, mineralized resurgent rhyodacite domes, strongly altered and mineralized tuffaceous lacustrine sedimentary rocks and an extensive crystal-lithic tuff debris apron. The orebody is hosted by intracauldron sedimentary rocks and breccias. Fluid inclusion data suggest that silver, lead and zinc were transported as chloride complexes and precipitated by cooling in veins from <5% (by weight) NaCl eq. fluids at 170° to 215°C. Silver spatially and perhaps temporally associated with resurgent rhyodacite was transported as a chloride complex and precipitated by increased H2S activity or increased fluid pH.

Jan 1, 2002