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By C. A. Rowland

Comminution efficiency can be expressed in three different ways. Theoretical Efficiency: actual energy consumed, in a comminution machine compared to the theoretical energy required to make the size reduction. Operating Efficiency: compares the operating work index, calculated from production comminution machinery operating data, to the Bond Work Index from bench scale comminution tests or calculated from pilot plant operating data. Economic Efficiency: income compared to planned income. Using the Bond Work Index and operating work index, this paper explains how to determine operating efficiency.

Jan 1, 1998

By H. G. Fleshman

Thousands of years ago, Chinese water well drillers developed a technique for punching holes in the ground by lifting massive metal bits and letting them fall against the rock. With diligence, they could pound away about 2 feet a day. The Chinese drillers pounded holes in the ground this way for almost 2000 years. In the 1860's, French water well drillers developed a perforated bit moistened by fluids pumped into the hole through a hollow rod. The fluids carried the cuttings from the hole and spared the Frenchmen the task of bailing them out by hand.

Jan 1, 1986

By Javad Sattarvand, Frimpong Kwaku Asare

The safe evacuation of miners during an emergency in the shortest amount of time is one of the most essential features of a mining operation. Despite advancements in mine evacuation research, the usage of mine vehicles during evacuation has not been considered. The majority of recent studies have been done on miners’ evacuation on foot. Mathematical formulations including Minimum Cost Network Flow (MCNF) models, Dijkstra's algorithm, Floyd-Warshall algorithm, and Ant Colony Optimization models have been used to solve mine evacuation problems. These models, which concentrate on determining the shortest escape routes during the evacuation, have been found to be computationally expensive and may not offer the best solutions in some cases. The goal of this paper is to incorporate light vehicles in the evacuation process using a mixed-integer programming approach. The methodology aims to minimize the total time required to evacuate the mine, ensuring minimal exposure of the miners to the adverse conditions that triggered the evacuation.

Jun 25, 2023

By D. D. Harbuck

Previous studies at the U.S. Bureau of Hines have shown that only 70 to 80% of the germanium in domestic zinc process residues can be extracted during H2S04 leaching. To increase germanium extraction, the Bureau developed and researched the hypothesis that minor amounts of germanium and zinc silicate, both present in zinc calcine, dissolve during the leaching stages of zinc processing, forming soluble germanium and silica gel. This silica gel then selectively adsorbs germanium from solution, rendering the germanium insoluble. Testing showed that as the amount of silica gel formed increased, the amount of insoluble germanium in the zinc residue increased. Several processing alternatives are presented for overcoming this problem.

Jan 1, 1991

By G. Almgren

With the exception of sublevel caving, the most common method of underground mining in Sweden is the "cut-and-fill" method. It is normally used for mining non-ferrous metals , and' is used extensively in the complex sulfide ore mines of the Boliden Company in north and central Sweden as well as the mines of the STORA and Vieille Montagne Companies in central Sweden. All in all, the cut-and-fill method is used in 13 of Sweden's 45 mines. As the mines are relatively small, the volume of ore mined by this method represents only about 5 % of the total ore production in Sweden. The commercial value, however, is much large than this percentage would imply. The production volumes and grades of some typical mines are shown in Table I. As seen, when rated internationally, the grades are comparatively low. The prices are set according to ?international metal prices? as dictated by the London stock exchange, and in lieu of governmental support, rational management methods are critical in order to achieve satisfactory profit.

Jan 1, 1975

By Alexander May

In its role of providing technology to promote the efficient use of minerals and mineral process waste, the U.S. Bureau of Mines has conducted research at: its Tuscaloosa Research Center to identify and develop high volume uses for phosphogypsum. Mixtures containing a maximum of 50 percent phosphogypsum, 6 to 10 percent lime, and the remainder fly ash had compressive strengths as high as 4,800 psi. The effects of the mounts of phosphogypsum, lime, and fly ash were investigated. Also, the effects of fly ash to lime ratios were studied.

Jan 1, 1983

By Robert R. Dorfler

We ought not look back unless it is to de- rive from past errors, and for the purpose of profiting by dear bought experience. - George Washington During the mid 1960's, the application of automation was introduced to Climax by two process control companies. In 1969 Climax decided to seriously consider improved control of selected areas of their milling process after preliminary research had been completed on two rougher ball mill grinding circuits. In 1971 the Climax Mill Department developed a direct digital control scheme for rougher milling, designed a remote control center for handling process water, planned to automate the central steam heating facility for energy conservation, and convert other plant areas to automation. All twenty rougher grinding mills and the industrial water system were automated by 1977. The idea of automating central heating and other areas was abandoned although some fuel conservation items were installed at the heating plant. During this period from 1971 to 1978, the mill capacity was expanded from 39,000 metric tons per day to 43,000 metric tons per day and cyclone classification was introduced to rougher milling. Ore quality changes degraded the milling recovery from over 90% to less than 85%. This report describes the procedure the mill used in developing the automatic process and the occurances that affected the timing and fina1 control logic. The report deals primarily with the automation of the ball mill grinding, classification and flotation process as this was the bulk of the seven-year project.

Jan 1, 1979

By Randhir Sehgal

Heavy media processes have been used for cleaning +28 mesh coals for a number of years, Two applications, i.e., the vessels and the cyclones are widely used in the U. S. for this purpose. The basic reason for the popularity of these systems is their extremely high efficiencies for particle sizes above 28 mesh, However, application of heavy media technology to fine coals below 28 mesh, has been limited due to the following reasons: o Inability to make size separations effectively at sizes below 28 mesh o Necessity of feeding large quantitites of magnetite to the separators o Difficulty of recovering magnetite in the presence of large quantities of coal o High levels of coal contamination in the recovered media, leading to high circulating loads and ineffective control of media gravity

Jan 1, 1981

By Erich U. Petersen

Chemical zoning studies of mineralization can be useful in guiding exploration efforts. They permit one to determine the limits of mineralization and to correlate mineralized intervals in drill holes. Fahlore minerals are well suited for zoning studies because they are common minerals found in a variety of deposits, exhibit chemical diversity, and record the chemical evolution of migrating hydrothermal fluids. Zoning information in the form of metal ratios preserved in fahlore minerals was used to determine ore body limits in the Orcopampa precious metal system, Peru, and to correlate between multiple ore horizons in a sediment hosted massive sulfide (SHMS) currently under investigation. The current generations of electron microprobes provide the most efficient, accurate and economic way to analyze the tens to hundreds of sample required to successfully describe and use zoning information at the mine scale.

Jan 1, 1991

By M. C. Fuerstenau

The zero-points-of-charge of apatite, calcite, and fluorite are pH 6.4, 10.8, and 10.0, respectively. Scheelite is negatively charged above at least pH 3. Flotation responses of these minerals in the presence of potassium oleate and sodium silicate are presented and compared with electrokinetic data. Colloidal silica appears to be the species principally responsible for calcite depression, while silicate anion is the species responsible for fluorite depression. Additions as high as 1 x 10-3 mole/liter silicate have no effect on the flotation responses of apatite and scheelite. Selective flotation of nonmetallic minerals is difficult to achieve with fatty acids or soaps by themselves. As a result, specific reagents are added to aid these separations, and one of the reagents commonly employed for this purpose is sodium silicate. Flotation separations of various calcium¬ bearing minerals such as fluorite from calcite (1,2,3) and scheelite from calcite(24) and apatite(2,5) almost always involve the use of sodium silicate, for example. The mechanisms by which sodium silicate functions as a depressant are still not understood; this fact is probably due to a number of reasons. That is, the dissolution process of sodium silicate is complex, giving rise to a number of ionic and colloidal species. (6) In addition, the type and concentration of these species depend on the ratio of Na20 to Si02, the concentration of sodium silicate, and the pH of the system. (6) At the present time, it is not known which species, colloidal silica or silicate anion, is responsible for depression. If colloidal silica is the species that is adsorbing, then adsorption must occur by electrostatic attraction between the colloid and the mineral surface. Silicate anion, on the other hand, may adsorb either physically or chemically. The objective of this paper is to determine first the active species of sodium silicate and then the conditions under which this species will adsorb and function as a depressant.

Jan 1, 1968

By David L. Daniels

The U.S. Geological Survey has for many years been flying and compiling aeromagnetic surveys. The aim is complete coverage of the United States, about half of which is presently done. Colored aeromagnetic maps at a scale of 1:1,000,000 are published as the states are completed; Minnesota and Colorado have been published. Michigan, Iowa, Nevada, Utah, Maryland and Virginia are presently being processed. Some of the most spectacular data collected to date is from the Piedmont of the Eastern United States. I am going to discuss a preliminary aeromagnetic map of the Piedmont region between New York and North Carolina, where coverage is nearly complete. This map has been compiled from many surveys. Flight spacing over Piedmont rocks is 1/4 to 1 mile with flight elevation of 500 feet above ground. The spacing over the Virginia Coastal Plain and Valley and Ridge regions is wider at 2 - 3 miles. Much of the data in Virginia has been produced by the Virginia Division of Mineral Resources. The map is colored on a spectral color scheme with red for the higher intensities and violet the low intensities. Each color represents a 100 gamma interval. Some of the highest intensities are beyond the range of the 13 colors - these are left white. It is necessary, of course, to remove first, the Earth's main magnetic field. The Geological Survey uses the International Geomagnetic Reference Field or IGRF (Fabiano and Peddie, 1969). The use of color in aeromagnetic maps is not new, but then not common. We have found that colored aeromagnetic contour maps are more useful by far than the uncolored versions because they allow the user to instantly compare intensities in widely separated areas and visualize long wavelength anomalies even when numerous short wavelength anomalies' are superimposed. One tends to see only steep gradients on uncolored aeromagnetic maps, the broad anomalies being quite invisible. We feel that colored maps take the place of various mathematically derived maps such as second derivative or averaged maps.

Jan 1, 1973

By P. Hadzeriga

Ion exchange techniques have been growing fast and spectacularly in all phases of Science for the last two decades, but still its acceptance as a unit operation in Metallurgy is resisted. Mainly this is because ion exchange procedures are thought of as glamorous techniques by which only relatively expensive metals are to be recovered. Perhaps this concept comes from the early and basic marriage of uranium and other high price metals and ion exchange procedures. The general trend is that ion exchange technique requires equipment and materials which are too expensive to economically perform a chemical step whenever "cheap" commodities are produced. However, we are here presenting a means of utilization of waste hydrochloric acid by an ion exchange technique. We have studied this from the engineering and economic standpoint in a number of variations of the main procedure discussed here and we-conclude that under proper economic circumstances, the cost of the ion exchange material as well as the equipment and labor involved in the ion exchange section, is by no means unreasonable.

Jan 1, 1964

By Thomas Schwind, Elmar Feigl, Gerald Skalla, Angelos Gakis

Cedarvale station was constructed as part of the Eglinton Crosstown Light Rail Line, under the operational Yonge-University Line Subway box of Toronto Transit Commission (TTC). The station was constructed as an open-cut, which necessitated the underpinning of the existing TTC box to minimize the impact on the Subway and allow its unhindered operation. Six mined galleries, 4 m wide by 2.75 m high, were excavated sequentially (SEM) immediately under the existing box, to provide the required space for the installation of the main underpinning beams. This novel solution was executed successfully providing quick access for the main excavation works to commence.

Dec 1, 2022

By A. T. Yu

Technology and economies of scale have, in the past decade, brought about the emergence of giant vessels. Meanwhile, to answer the need for rapid dispatch, as a means of combating the proportionately far greater demurrage charges, shiploading and unloading speeds have soared (Ref. 1, 2, 3). As the loading and unloading rates have dramatically increased, so has the cloud of dust grown in unbearable proportions. It not only has threatened to be a real menace to machinery and men, but in certain instances has also seriously jeopardized fish and marine life (Ref. 4). In an era when ecology is king, dust in shiploading and unloading can no longer be shrugged off as a mere public nuisance, and its control is now duly recognized as of grave concern to all. Even if public outcry were not a problem, from the operator's own parochial point of view, dust can adversely affect productivity and the well-being of the operating personnel. Without adequate control, it can also result in costly equipment maintenance, particularly when the dust is micronic in size, and abrasive. The Hierarchy of Control Techniques Given the great fortune of not yet having to deal with gas and odors, in the jargon of pollution control, our problem is confined to having to control "particulates" only. To deal with "particulates", the myriad of dust control techniques can be utterly confusing to those who are not entirely well versed in the methodology. Our analysis of what is available to date results in the following hierarchy of logical preferences: 1. Prevention 2. Removal 3. Suppression 4. Containment 5. Dilution Since it deals with the root cause, prevention always outranks the cure. Once the dust is generated, removal nips it in the bud. Only when dust removal is

Jan 1, 1972

By S. B. Keith

Cerro de Pasco Corporation operates five large base metal mines in Peru having a combined production of some three million tons of ore a year. An integrated complex of concentrators, smelters and refineries produces annually about 25,600 short tons of copper, 48,100 short tons of lead, 60,500 short tons of zinc metal, 102,300 short tons of zinc concentrate, 8,272,000 ounces of silver and substantial amounts of bismuth, cadmium and selenium. Geology plays an important role in these operations. The organization of detail geologic work in and around the Cerro mines was set up by John M. Boutwell in 1918 and a geology department was established in 1920. Growing through the years, the department technical staff now numbers over thirty men and. their work covers all phases of geological investigations. Many outstanding geologists of the past and present, too numerous to name here, have studied and contributed to the knowledge of the deposits and the ever growing list of Cerro "alumni" must rival that of any other mining organization. Numerous papers on the geology of Cerro's mines can be found in the technical literature and several doctoral theses have been presented on Cerro subjects as indicated in the attached bibliography, Specimens of Cerro's ores can be found in museum, college and university collections throughout the world. Yet, as with all mines and mining districts, the geologic knowledge of Cerro's deposits in Peru is being revised and added to constantly. This presentation cannot hope to cover adequately all the phases of the geology and mineralization. For a more complete background and discussion of the mine you are referred to the bibliography. Here I shall outline only briefly the more important geologic features and describe some of the newer developments of recent years The credit for the data presented here belongs to the many geologists who have worked or are now working for Cerro de Pasco Corporation, but I must assume sole responsibility for any omissions or variations in the interpretation of their work.

Jan 1, 1965

By Lawrence P. Bonicatto

The steel industry's increased demand for higher grade pellets has caused the pellet producers to investigate methods of upgrading their product. The Hanna Mining Company's Groveland plant is no exception. The Groveland Mine is located in Dickinson County on the Upper Peninsula of Michigan. The low grade iron deposit is a complex mixture of magnetite and hematite with chert, quartz, jasper, and various iron silicates. (1) Beneficiation is by Humphrey spirals and anionic flotation of the iron minerals. (2) A general flowsheet is shown in Figure 1. Flotation of the spiral tailings makes up about 75% of the concentrate. A minor amount of concentrate, less than 3%, is produced in magnetic circuits. The concentrate is pelletized at the rate of 1.6 million tons per year.

Jan 1, 1968

By T. V. Subrahmanyam

Unlike coarse particles (40-50 µm), the fines (<10 µm) have low collision efficiencies with gas bubbles in flotation process. Among the alternative methods for recovering the fines are their aggregation with coarse particles (carrier flotation) and flocculation of the fines alone (shear-flocculation), prior to flotation. In any case, hydrophobic aggregation is the mechanism involved though the technique is known by different names in literature. This paper deals with theory and state-of-the-art of particle aggregation. To illustrate the dependence of aggregation on particle hydrophobicity, charge and, in turn, the sheer force, the results of quartz-DDACI and galena-xanthate systems are considered. In the flotation of complex ores selectivity is achieved by chemical control and aggregation of particles of the same species is analogous to that; however, more work is necessary on ores for a better understanding of the pulp chemical aspects from the view point of selectivity in aggregation. For a few ores, the results of earlier workers confirm improved recoveries of fines by aggregation prior to flotation.

Jan 1, 1997

By Shosei Serata

In the past, salt cavities for storage of liquid and gaseous fuels have been developed and operated using practical experience as a guide rather than rock mechanics principles and practices. Although many salt cavities are still operating satisfactorily. some of them are beginning to show various problems associated with long-term deterioration of the cavities. This paper describes a major breakthrough in the rock mechanics design of solution cavities which is the development and application of the REM computer simulation system. From the computer simulation analysis, the long-term deterioration process of cavities can be related to the basic parameters of rock mechanics design and the storage operations. The computer simulation system is also used for optimizing cavity design and operational specifications. This optimization technique is explained by its application to the three basic storage systems: 1) open dry storage system for liquids and solids 2) open wet storage system for liquids 3) pressurized storage system for gases, liquids and solids The effectiveness of the optimization technique is illustrated with some field examples by showing the direct interaction between the computer simulation system and field data of a test well including tectonic stress conditions, material property coefficients and geological anomalies.

Jan 1, 1974

By Kenneth P. Katen

Though the use of continuous mining machines consolidated the operations of cutting, drilling, blasting, and loading in one machine that would theoretically provide uninterrupted production, it was soon realized that the face haulage and roof support operations remained as major impediments to continuous production. The ability to provide not only continuous cutting and loading, but also continuous haulage and roof support (see Fig. I), was the basis for the introduction of mechanized longwall systems in this country from Europe in 1951. The early systems employed friction props for roof support, but were to become obsolete shortly after introduction of the first hydraulically powered, self-advancing supports in 1960. Since then, use of the longwall technique has grown to the point where it is currently providing more than 5% of the annual output of underground coal mines in the United States. The shortwall system had its origin in Australia, but was first introduced into this country in 1962 following the development of powered roof supports. It, too, provides for continuous cutting, loading, and roof support (see Fig. 2), but has not experienced the widespread popularity of longwall due to its inherent inability to easily provide for continuous haulage. While there are in the neighborhood of 100 longwall systems currently in operation in this country, there are only a handful of short- wall operations providing production of slightly more than 907 184.7 t/a (1,000,000 stpy) Both of these systems provide uninterrupted roof support for face operations by means of hydraulically powered steel roof supports. In each case, the coal removal consists of open-end cuts made from the narrow end of a large rectangular pillar (panel) which has been blocked out by continuous miners developing entries around its perimeter. However, this is the extent of the similarities between the two systems. It is hoped [ ] that the information presented in this chapter will enable the reader to better understand the two mechanical systems and the mining concepts involved in their employment.

Jan 1, 1981

By R. J. Andreini

Solvent extraction is widely used in hydrometallurgical processing of uranium for purification and upgrading leach solutions prior to recovery of metal values. Conventional solvent extraction processing utilizes mixer-settler units to achieve mixing of the aqueous and organic phases. Use of mixer-settlers permits continuous treatment of feed, but the processing rate is restricted by the time required for phase separation after mixing. Because of the high-shear type mixing used in a mixer settler a portion of the organic phase becomes mechanically entrained in the aqueous resulting in loss of extractant. For this reason application of mixer-settler units is often limited by the settling area required for phase separation, especially for systems where high volume throughputs are desirable or necessary. Several alternatives to mixer-settler operations involving the use of column extractors have been proposed. Packed columns (1-2), in which organic and aqueous phases are fed countercurrently, utilize packing materials similar to those used in gas absorption or distillation columns. Extraction columns utilizing rotating(3-5) or reciprocating elements(6-7) to achieve mixing have also been developed. Van Dijek(8) originated pulsed columns, in which mechanical or air pulsing of the phases enhances the mixing in the vessel. Each of the above column processes involve varying degrees of mechanical complexity which may lead to operational difficulties.

Jan 1, 1975