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By Ernest L. Ohie

In 1939 the Geological Society of America published a summary of the geology of the ore deposits of the Mississippi Valley region, This volume, edited by E. S. Bastin, contained contributions from the foremost students of the area which described theregionalgeologic setting of the various deposits as wel as the detailed geology as then known. The various ideas as to the origin of the ores were discussed with the general, though not unanimous, conclusion that the deposits were hydrothermal products, Only those deposits in the immediate Mississippi Valley area were considered without any attempt to introduce evidence from other districts generally accepted as being of the "Mississippi Valley type." Since 1939, much new information has come from extended studies of two of the important districts described in the 1939 report andimportant extensions of the known ore have been found. Likewise, concentrated geologic efforts have been fruitful in severa "Mississippi Valley type" districts - both U. S. andforeign - not treated in the 939 paper. The wealth of new field information on the structural and stratigraphic relations of this interesting ore type, coupled with the results of theoretical and laboratory studies of the past 18 years, makes desirable a review of our present knowledge and interpretation of these important deposits which for many years have yielded over 20 percent of the world's annual production of lead and zinc, together with large amounts of fluorspar and barite. No restatement of the details of the geologic evidence willbe attempted here; the interested student is referred to the papers cited. Slide No. 1 shows the distribution around the world of the deposits under consideration. A principal thesis of my remarks is that there is so much similarity in all these deposits that it seems necessary for all of them to have had a similar mode of origin, whatever that may be. Variations in the shape, size and mineralogy of the orebodies give each district some individuality, but there are enough of the "typical" characteristics present in all cases to make classification in the "Mississippi Valley type" agreeableto most geologists. Thus the overall process giving rise to the ore solutions surely was the same for all in the group. Either they all have igneous affiliations or they all do not. Acknowledgment of this kinship between deposits in the various districts offers many advantages in trying to arrive at a decision as to just what the origin may have been, for the amount of guiding and limiting evidence which must fit into the hypothesis is greatly increased over that available in any one district, To a certain extent this was recognized by the authors of Special Paper 24 in treating all of the immediate Mississippi Valley areas together; by expanding the consideration to include ore deposits of this type all over the world the changes of success, i.e., arriving at the correct answer, are improved several fold. Since most of these districts are quite simple structurally, a number of hypotheses might fit the facts in any one of them, but if the facts to be met can safely be drawn from all the districts, then the explanations which will fit all the data are much less numerous. One purpose of this paper is to call attention to the field facts that have been reported from the .various areas which seem to have an important bearing on the kind of ore fluid that was responsible for the ore and on the way it circulated.

Jan 1, 1958

By J. Driscoll, T. Morson, Ross M. Workman

The study investigates the effectiveness of the canopy air curtain (CAC) in reducing respirable dust exposure for shuttle car and ramcar operators in underground coal mining. Field testing showed that the CAC reduced dust exposure by 11-34% overall and by 57-65% during ramcar loading by the continuous miner. These results demonstrate the CAC’s potential as a significant dust control device.

Feb 19, 2022

By K. W. Morris

Of the fossil fuels used for power generation coal is by far the most variable and complex in its properties. A thorough review of the characteristics of the coal to be fired is essential before boiler design can begin. Major parameters such as heating value, moisture content and ash properties will determine not only the boiler size and configuration, but also the performance of the unit with respect to the thermal efficiency, particulate and gaseous emissions, and unit availability and reliability. An example of a review completed on a large low-rank coal deposit for a power plant will be described.

Jan 1, 1983

By E. Wm. Heinrich

Glass sands fall into that extremely select category of mineral deposits that requires a fantastic degree of natural concentration (95% +) of a single component before they can even be considered as ores suitable for further refinement. The combination of geological factors that has produced such an environment of "mineralogical single-mindedness" has appeared only rarely. Factors that require consideration in the economic evaluation of a potential glass-sand deposit can be grouped into three categories: 1) geological (e.g., size, shape, structure); 2) petrographic (e.g., grain size, accessory minerals, nature of iron contaminants); 3) geographic - political (e.g., proximity to consumer, size of market, zoning restrictions). Of particular con ern is the nature of the iron contamination. Iron-bearing species appear as 1) accessory mineral grains, either detrital or authigenic, 2) cements, 3) grain coatings, and 4) quartz-grain inclusions. Selection of the cheapest form of beneficiation requires precise information on the mineralogy of the iron species and their detailed petrography. Because of the antipathetic relationships, in many parts of the United States and Canada between the geographical locations of glass plants and the geological distribution of glass sands, the selection of ac suitable source for a particular glass plant may be dichotomous. One may seek either an exceedingly pure "classic" type glass sand that is relatively distant and whose cost includes a major transportation charge or a relatively proximate and somewhat "impure" source whose cost includes a substantial fee for beneficiation.

Jan 1, 1974

By Jerome E. Grader

Special-purpose analog computers are being profitably applied in the process industries to perform miscellaneoas online computing functions in situations where conventional measurement and/or control hardware cannot perform a required task satisfactorily. This paper will discuss the application of such equipment in the mining industry. It is divided into two parts, beginning with a description of operation of the hardware, followed by a discussion of several applications of the computers to mining industry control problems.

Jan 1, 1969

By E. McCarthy

"INTRODUCTION Talc is a hydrous magnesium silicate with the approximate elemental composition 4MgO.3SiO2.H2O. It is one of the layered phyllosilicates (like kaolin and mica) but it differs from these in that it is relatively hydrophobic. This is due to its unique crystalline structure whereby a brucite inner layer is sandwiched between silica layers and the adjacent silica layers have no interlayer bonding other than van der Waals forces. This allows talc to be sheared easily along this basal plane, and the surface is covalent not ionic. Talc occurs both as a relatively pure material (>90% talc content) and in conjunction with many other minerals in proportions all the way from 1% to 90%. At lower concentrations, it is often considered a nuisance mineral when it occurs with base metals like copper, molybdenum or nickel or with precious metals like platinum or palladium. It floats readily with these materials and often is suppressed using guar gum or carboxy methyl cellulose which will absorb along the basal surface and make it hydrophilic. Alternately if the reduced ore is hydrophobic, like MoS2, then a partial oxidation of the sulfide will convert the surface to a hydrophilic oxide and the talc can be floated away in a separate step. Talc in grades from 20 to 90% has been commercially exploited in a wide range of pigment (paint and paper), material (ceramic, construction and cosmetic), reinforcing (polymers and composites) and functional (pitch adsorbent, lubricating agent) applications. Initially these tended to be local or regional markets, but eventually with certain higher purity grades, cosmetic, polymer and ceramic applications became valuable enough to be national and trans ocean markets. TALC FLOATATION PLANTS This drove the need for higher purity grades of talc and initially this need was met primarily by ore sorting. This works well for certain deposits with well crystallized talc lenses, but for ores, such as those from widely available ultramafic deposits, where the liberation size is closer to 100 microns, sorting is not effective. That drove the need for floatation and the first investigations were published by Clemmer and Cooke of the US Bureau of Mines in 19362. The first commercial floatation plant was installed in Johnson, VT by the Eastern Magnesia Talc Co in 1937. The circuit is shown in the schematic (Figure 1). The ore was an ultramafic, serpentine derived talc; mineralogy was about 55% talc, 40% ferroan magnesite and 5% oxides, sulfides and other silicates. The oxides include hematite and chromite, sulfides pyrite and gerstorffite and silicates chlorite, serpentine and mica. After crushing, the ore was dry ball milled and then air classified to remove minus 325 mesh fines. The coarse fraction was further classified to cut at about 100 mesh and the fines from this were the feed to floatation. The -325 mesh (about 15% of the ore) was sold as a paint grade and the plus 100 mesh (about 25% of the ore) was screened to make an asphalt backsurfacing grade."

Jan 1, 2018

By J. van Wijk

"Vertical material transport is one of the major challenges for the successful implementation of deep sea mining projects. The EU research project „Blue Mining” is focusing on sustainable solutions for deep sea mining operations, with one major goal being the advancement of Vertical Transport Systems (VTS). To investigate flow effects under realistic conditions, especially clogging effects, a 136 m high test facility for flow analysis in vertical transport has been constructed using available mining infrastructure. Tests are run in a closed circuit, using a system of downfall and riser pipelines connected to a compact sediment injection- and separation unit as well as the centrifugal pump. The riser is equipped with pressure sensors, as well as temperature sensors, flow meter, concentration meter and high speed camera to allow comprehensive analyses of the flow regime and behavior of transported material within the flow. Additional mobile measurement devices allow wear and tear analyses of pipe material. This paper focuses on the determining factors of the tests leading to the design as well as the installation and trial of the test facility itself and explains the used components and work principles. INTRODUCTION Since the 1970s several research projects had been conducted investigating in the possibility of deep sea mining. In recent times projects for deep sea mining operations have started again, considering the rising demand on natural resources, especially raw earth elements. Yet projects like the Nautilus project on the deposit Solwara 1 [1], or Japanese projects focusing on the region of Okinawa [2] and Chinese projects [3] planning on depths of “only” about 2,500 up to 3,000 m. Until now no economical deep sea mining project was realized, due to the enormous difficulties of deep sea environments. Vertical material transport is one of the major challenges for the successful implementation of deep sea mining projects, considering transportation heights up to 5 km. The EU research project „Blue Mining” is focusing on sustainable solutions for deep sea mining operations, with one major goal being the advancement of Vertical Transport Systems or VTS [4]. Critical parts of the system would be identified and investigated to deliver solutions and higher the technology readiness level to a level were planning of a pilot project can be considered. At first case examples for mining projects of seafloor massive sulfides (SMS, 1,600 m water depth) and manganese nodules (MnN, 5,000 m water depth) had been calculated on basis of economical frame conditions, such as planned production rates to be efficient. As depicted in Figure 1 two major possible systems had been used for comparison, airlift system and pump system, considering multiple pump stations or single pumps. Based on the results and comparisons for the calculated vertical transport systems critical components and flow effects had been identified."

Jan 1, 2018

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 David G. Chedgy

It is probably safe to assume that most operating personnel working in coal preparation plants are exposed to noise levels in excess of the MESA Noise Regulations unless they are wearing ear protection. The excessive in-plant noise levels have received little attention until recently. Noise control has not been an important design consideration in existing coal preparation plants. This situation is rapidly changing as plant owners and plant operators are requiring that new coal preparation plants be designed to provide a safe noise environment for operating personnel and also meet MESA Noise Regulations. This paper discusses the noise exposure hazards, noise generating mechanisms, and some possible noise control solutions for typical coal preparation plants.

Jan 1, 1975

By O. A. Bascur

In recent years, metal-producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Transformation to a digital plant can fundamentally revolutionize how industrial complexes operate. The abundant and growing quantity of real-time data and events collected in the grinding and flotation circuits in a mineral processing plant can be used to solve operational issues and optimize plant performance. A grade recovery model is used to identify the best operating conditions in real time. The strategy for increasing the value of instrumentation in current plants is reviewed. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut size to reduce metal losses in the flotation circuits. Sensors in flotation circuits enable an estimate of the recovery and determination of the optimal froth depth and aeration using an air hold up flotation model. A strategy of classifying data for on-line generation of insights to using operational intelligence tools is described. The implementation of a recovery/grind strategy with industrial examples in non-ferrous mineral processing is presented.

By Mark E. Gershon

A mixed-integer formulation of the mine scheduling problem is discussed and applied for the purpose of optimizing both the mine production sequencing and the mill blending and processing problems simultaneously. Previous attempts at solving these problems separately, although successful, fail to take into account the interrelationships between these problems. Project structure serves as the outline of this paper, which is directed towards a mining engineering audience. Generalized in its organization, this concept is useful for long, intermediate and short range scheduling. Actual applications are mentioned which show that the concept is also applicable to mining a variety of ores.

Jan 1, 1982

By James R. Jones

It has been 2-1/2 years since the Congress passed the Surface Mining Control and Reclamation Act of 1977 (PL95-87) the Office of Surface Mining every deadline specified in the Act. Hopefully the Congress will begin to realize that specifying unrealistic deadlines does not accomplish the end desire of legislation any sooner -- it only adds to the confusion, and actually hinders orderly, efficient progress. OSM has been sued by all categories of involved parties -- environmental activitist organizations, the states, and the coal operators. This situation has resulted for two reasons: (1) insufficient time was allotted by the Congress to properly develop the regulations and program, and (2) OSM?s philosophy that it must dictate every detail of reclamation operations from Washington, even though many of its people are inexperienced with coal mining. These law- suits are now demonstrating their value. OSM is showing signs of "pulling-in-its horns" and, hopefully, will approach the revised regulations in a more realistic fasion.

Jan 1, 1980

By MANZOOR ALI BROHI, IZHAR MITHAL JISKANI, Atta Ur Rehman, SHUAI HAN, MUHAMMAD TARIQ, NIAZ MUHAMMAD SHAHANI

The analysis of mine safety indicators using a scientific method can improve mine safety and assist management in making informed decisions. This research establishes a mine safety evaluation index and proposes an integrative evaluation model based on the entropy weight and grey clustering methods. The index consists of 27 indicators classified into seven criteria: working environment (A), miners’ attributes (B), safety policies and education (E), prevention and control (F), and monitoring and supervision system (G). Using Pakistan’s mine safety situation as a case study, the proposed model categorized the indicators into five safety levels (very low, low, medium, high, very high) for the present situation and for their relevance in terms of future safety improvement. The results show all of the criteria falling into the very low level for the current mine safety situation. Three of the criteria — C, E and G — are identified as having very high levels of significance for future safety improvements.

By Georgios Bartzas, Vasiliki Karmali, Konstantinos Komnitsas, Anna Kritikaki, Dimitra Vathi, Stylianos Tampouris, Arne Peys

Large volumes of slags, with varying mineralogical and geochemical characteristics, are produced annually by the ferrous and nonferrous metallurgical industry. Most of them are considered as potential secondary resources and may be valorized, following the principles of circular economy, for the recovery of critical elements, including energy transition metals. Apart from the economic benefits, valorization of slags may contribute to the competitiveness of the metal industry and the conservation of natural resources. Valorization also results in minimization of environmental impacts on soils and waters in slag disposal areas, due to the prevention of solubilization and subsequent migration of potentially hazardous elements. The present study utilizes ferronickel (FeNi) slag for the production of alkali-activated materials. The effects of the main experimental parameters, including sodium hydroxide (NaOH) molarity, silica/sodium oxide (SiO2 /Na2O) molar ratio in the activating solution, precuring and curing time, curing temperature and aging period on several properties of the final products, are assessed.

Apr 1, 2025

By George L. Atwood

The western phosphate field, one of the United States' great mineral resources, lies within the western states of Idaho, Utah, Wyoming and Montana. This Permian sedimentary deposit has been known since the turn of the century and since the 1920's has been mined for its phosphate content. Isolation from markets and relatively high mining costs have restricted development as compared to eastern United States deposits, but nevertheless a significant western phosphate industry has developed. Geographically the deposit covers an enormous area of about 337 000 km2 (130 000 sq miles). It covers Idaho from Pocatello east- ward, western Wyoming to the eastern flank of the Wind River mountains, and extends well into southwestern Montana and into a large area of northeastern Utah north of the Uinta Basin and east of the Salt Lake valley.

Jan 1, 1983

By G. A. Kordosky

The control of pH in solvent extraction circuits is an old technique (1,2) but one which has a large potential for future use. The equilibrium position of any reaction which has hydrogen or hydroxide ions, either as products or as reactants, can be controlled by pH adjustment. Several examples of reaction types which are important in solvent extraction systems and which also show a pH dependence are shown in Figure 1. The examples were chosen to show the wide variety of reactions which fit the above criteria, but it is not meant to be a complete listing of all the possible reaction types, Some of the reactions are presented in a simplified form. It is the intent of this paper to discuss pH controlled solvent extraction reactions for some relatively simple systems through more complex ones.

Jan 1, 1979

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By David W. Wisecarver

Kennecott Copper Corporation and the U. S. Bureau of Mines cooperated in a full-scale slope stability research project at the Kimbley Pit near Ely, Nevada. The west wall of the Kimbley Pit was mined from an over-all slope angle of 45° to an over-all slope angle of 57° and the pit was deepened nearly 50 feet. Mining was begun February 10, 1966, and completed October 30, 1966. Approximately 2.55 million tons of ore and waste were mined. The project was designed and carried out to learn more about the behavior of a pit wall as its slope angle is steepened and to obtain a possible insight into engineering parameters for use in design of future slopes. Data from this project are presented as obtained from (1) instruments installed in two adits for deformation and displacement measurements, (2) a subsidence network installed on the surface above the steepened wall, (3) pre- and post-mining observations of stress in rock, (4) sonic-velocity measurements, and (5) seismic and microseismic investigations. Changes occurred in measured quantities as the slope was steepened but stopped when mining was completed. Agreement was noted between the measured changes and predicted changes obtained from calculations using the finite element technique. Subsidence surveys and microseismic studies show the steepened pit wall to be stable.

Jan 1, 1968

By Larry L. Snyder

A compact 4.87 m (16 ft) diameter tunnel boring machine (TBM) is capable of boring a 12.2 m (40 ft) radius curve while gripping horizontally, or vertically, as may be required for the excavation of turnouts. The machine's 5.0 m (16.5 ft) length and a patented machine structure allows steering while boring without causing harmful eccentric loads. An extremely stiff thrust system, rigid front and rear grippers, and the torsional stiffness of a front end electric cutterhead drive combine to create superior machine stability and boring efficiency. A 2.2 m (7.2 ft) diameter prototype, complete with a soft ground shield attachment, was used successfully on a tunnel project in Scotland.

Jan 1, 1989

By Iga Trisnawati, Fitria Puspita, Himawan Tri Bayu Murti Petrus, Gyan Prameswara, Idi Amin, Andi Nurfaadhilah Ulfah

Laterite ores, rich in essential metals like nickel, iron and cobalt, are a crucial resource for modern technology. However, the extraction of nickel from laterite ores is a complex process due to their intricate mineral compositions and low nickel concentrations. This paper presents the results of a study to understand the leaching behavior of preroasted laterite ore and the impact of roasting on leaching kinetics. The ore was subjected to roasting at 280 and 610 °C for a duration of three hours, followed by leaching in sulfuric acid (H2SO4) under atmospheric conditions. The results show that preroasting the ore at 610 °C significantly improved the recovery of nickel during leaching, with recovery rate of up to 93 percent, and the leaching process of the preroasted ore was primarily controlled by diffusion through the ash layer. The activation energy values were found to be 20.97 kJ/mol for the ore roasted at 280 °C, and 18.97 kJ/mol for the ore roasted at 610°C. These findings suggest that preroasting can enhance the leaching performance of laterite ore, potentially paving the way for more efficient and sustainable nickel extraction processes.

Aug 1, 2024