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By Howard J. Brown

The Lucerne Valley limestone mining district is in the San Bernardino Mountains, one of the major ranges in the Transverse Range Province of southern California. Several large limestone mining operations are present along the north range front in Lucerne Valley, and the area is one of the premier limestone mining districts in the country. Resources are contained in Paleozoic carbonate rocks that are part of a thick late Precambrian and Paleozoic sequence that uncomformably overlies crystalline basement. The district has been affected by multiple episodes of metamorphism and deformation, as well as by a complex sequence of late Cenozoic structural events. Detailed studies, however, have demonstrated that these rocks can be divided into formations correlatable with late Precambrian to Permian strata of the Cordilleran miogeocline. The district is the leading producer of white, high-purity calcium-carbonate products in western North America. Pluess-Staufer (California) Inc. mines and processes high-purity white limestone from extensive deposits, and is one of the largest producers of high-quality limestone fillers and extenders in the western United States. Major factors influencing the genesis of economic carbonate deposits in the district include depositional environment, post-depositional processes such as diagenesis, dolomitization and/or silicification, regional and/or contact metamorphism and associated intrusive activity, faulting, folding, uplift and erosion, and preservation from erosion. Regional geologic studies, detailed geologic mapping, intimate knowledge of stratigraphy, and recognition of complex structural relationships have proven to be invaluable tools in the discovery of high quality calcium carbonate deposits in the district.

Jan 1, 1987

By K. Awuah-Offei

The objective of asphalt mix design is to produce a mix with optimal performance using available aggregate stockpiles. Often, this process does not take into consideration aggregate plant stockpile inventories or the cost of aggregate in the mix. This is due to the lack of tools that enable the lab technician or the engineer to optimize the mix for good performance while reducing the cost of aggregate and managing the stockpile inventory levels. The Bailey method provides useful guidance on aggregate gradation selection for optimal performance. This work presents a linear programming model of the asphalt mix design problem. The algorithm is implemented in MATLAB as an Asphalt Mix Design Optimization (AMIDO) program. The program is successfully validated with real-life data. The results show that AMIDO can be used to successfully produce any mix design with known Bailey method ratios. Also, RAP can be included in a design easily by making use of the Bailey method ratios and AMIDO. This work improves the state-of-the-art in asphalt mix design for dense graded mixes and could potentially be modified for other mixes.

Jan 1, 2009

By William R. Yernberg

The combined 80th Annual Minnesota Section of SME Meeting and 68th Annual University of Minnesota Mining Symposium was held April 17 and 18, 2007, in Duluth, MN. About 350 mining industry professionals attended the conference, including engineers, executives, mining managers and suppliers from the United States, Canada, Australia, Finland and Brazil. This year’s theme was “Consolidation – Growth – Technology.” The 80th Annual Minnesota Section of SME meeting included concurrent technical papers sessions, a keynote session that featured two distinguished speakers and a general managers session in which taconite mine operators provided updates on their operations. The Minnesota Section meeting also offered an SME short course titled “Control the Feed, Control the Mill.” More than 50 individuals at-tended the short course.

Jan 1, 2007

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dusts escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dust hog-type bit to improve dust extraction during the critical initial phase of drilling. A twisted-body drill bit is also evaluated to determine the quantity of dust liberated by comparison to the dust hog-type bit. Based on these laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emissions can also be substantially reduced. The use of a twisted-body bit has minimal improvement on dust capture compared to the commonly used dust hog-type bit.

Feb 27, 2013

By K. A. Smith, X. Cheng

Introduction The separation of minerals from complex sulfide ores by flotation requires careful control of the surface chemical behaviors of the minerals constituting the ores. When the minerals in the ore are finely disseminated, extremely fine grinding is needed to liberate the minerals. Fine grinding is not only an energy-intensive operation, but also influences the flotation behaviors of liberated minerals. Steel balls are commonly used for grinding. Galvanic interactions occur not only between sulfide minerals and grinding media but also among the different sulfide minerals themselves. The electrochemical characteristics of chalcopyrite and pyrrhotite when they are independently coupled with steel grinding media and the relevance of these characteristics to the flotation behavior of these minerals have been exten¬sively studied (Cheng and Iwasaki, 1992: Li and Iwasaki, 1992). These studies dealt with reactions in two electrode combinations, simulating mineral-grinding medium and mineral-mineral interactions. In practice, however, it is more common to involve more than one sulfide mineral. In a study of a pyrite-pyrrhotite-mild steel system, Pozzo et al. (1989) provided evidence that a mineral having an intermediate potential could behave differently, depending on the condi¬tion of galvanic contact. This investigation was undertaken to study a chalcopyrite-pyrrhotite-mild steel system to gain better in¬sight into the mechanism of multiple galvanic interactions. A three-electrode system was chosen to simulate a typical copper sulfide ore. The sulfide minerals were represented by chalcopyrite and pyrrhotite. The grinding medium was rep¬resented by mild steel. The nature of galvanic interactions involving these minerals and grinding medium in an oxygen atmosphere was investigated in a three-electrode combina¬tion, and an attempt was made to relate the laboratory flotation results of pyrrhotite-chalcopyrite ores. Possible implications to the differential flotation of complex sulfide ores are discussed. Key words: Electrochemistry, Flotation, Sulfide ores Experimental The pyrrhotite (57.74% Fe, 0.09% Cu, 4.84% Ni and 36.54% S) sample was obtained from Falconbridge Ltd.'s Strathcona mine, Ontario, Canada, and the chalcopyrite (26.00% Cu, 28.57% Fe, 0.05% Ni and 31.52% S) sample came from Transvaal, South Africa. Mild steel (AISI 1020, 0.2% C) was chosen to represent grinding media. A conventional three-electrode cell was used in the elec¬trochemical measurements. The working, counter and refer¬ence electrodes were, respectively, sulfide minerals or mild steel, graphite rod and saturated calomel electrode (SCE, 0.245 V vs. standard hydrogen electrode). The exposed areas of the sulfide minerals and grinding medium electrodes were approximately the same (0.17 to 0.19 cm2). The preparation methods of working electrodes, the reagents used, the experi¬mental procedures and the instrumentation were the same as those described previously (Cheng and Iwasaki, 1992). Rest potentials of pyrrhotite, chalcopyrite and mild steel were measured individually in 0.05-M sodium sulfate solu¬tions. Combination potentials and galvanic currents of the sulfide minerals and grinding medium were measured in short-circuited two- and three-electrode systems. All poten¬tials in this study are quoted in volts with respect to the standard hydrogen electrode (SHE). To simulate the constantly abrading conditions in a ball mill, rest potentials, combination potentials and galvanic currents were also measured by rotating a porcelain ball against chalcopyrite, pyrrhotite and mild steel electrodes in

Jan 1, 2000

By Haydn H. Murray

Since the advent of machine coated paper in the mid 1930's, the kaolin industry has had a remarkable growth, In 1935 the domestic production of kaolin was 500, 000 tons and in 1970 the estimated production was in excess of 3. 5 million tons. The process industries which use kaolin most extensively are paper, rubber, paint, ceramics, plastics, catalyst manufacturers, ink, and pharmaceutical. The paper industry is by far the largest consumer of kaolin using approximately 70 per cent of the total tonnage mined and beneficiated. Up until 1970 the major kaolin producers were able to expand rapidly enough to supply the demand but for the first time in thirty years the demand is expected to be in excess of mining and beneficiation capacity through at least 1975. The major reason for this is the expansion of coated paper production in Europe and Japan. Two areas supply the lion's share of kaolin for the world markets. These are the Cornwall area in extreme southwestern England and a limited area of Georgia and South Carolina in the southeastern U. S. The English kaolins are primary - (found in decomposed granite) whereas the Georgia-South Carolina kaolins are secondary - (found in lenticular, continuous beds in the Tuscaloosa formation of Cretaceous age. ) The English kaolins are mined by hydraulic methods whereas the Georgia-South Carolina kaolins are mined by dragline or shovel and benefidated by using a wet process for the majority of the production and/or a dry

Jan 1, 1971

By Thomas L. Craig

The Wellman-Lord SO2 Recovery Process is operating commercially at one location in this country and at two locations in Japan. Tail gases from a sulfuric acid plant, from an oil fired steam generator and from a sulfur recovery unit are the respective applications. 1) At the Olin Corporation's Paulsboro, New Jersey, stack gas from a spent acid regenerative sulfuric acid plant-45000 SCFM - is treated in the W-L unit to reduce sulfur dioxide concentrations from 4500 ppm to less than 500 ppm. 2) At the Japan Synthetic Rubber plant in Chiba Prefecture, stack gas from an oil-fired steam generating plant - 120,000 SUM - is reduced from 2100 ppm S02 to less than 200 ppm. 3) At the Toa Nenryo Kogyo refinery in Kanagawa Prefecture, tail gas from a sulfur recovery (Claus) unit - 41,000 SUM - with, an inlet SO2 concentration of up to 13000 ppm is reduced to less than 200 ppm. The three installations are operating successfully and are capable of reducing S02 emissions to levels significantly below the concentration guaranteed. With the one exception of a higher than guaranteed chemical make up requirement at Paulsboro, utility and chemical requirements will be less than design.

Jan 1, 1971

By K. W. Harris, K. A. Perry

Underground coal mines beneath Black Mountain in the Harlan County district of the Central Appalachian coalfields have an extensive history of bump events, which yields an elevated probability for significant injury or fatality to underground miners. According to Mark (2009), Harlan County has had the greatest concentration of deep-cover retreat mining in the United States. Combined with the extensive multiple seam mining history, room-and-pillar coal bumps have had a disproportionate impact on coal operations in this region. The Harlan seam, one of the principal, economically recoverable coalbeds exploited beneath Black Mountain, has a significant burst history that extends into modern times. A numerical investigation using the LaModel software of 17 bumps that occurred at the same mine in the Harlan seam was conducted and used to create a calibration methodology which serves as the quantitative basis for current and future numerical efforts in an adjacent mine exploiting the same reserve. In addition to this numerical study, a qualitative assessment of the geologic factors that are believed to contribute to the bump potential was completed. Combined with stability prediction using the numerical basis, these geologic factors will be used for recognition of high bump potential areas with the goal of reducing the potential for future bumps, helping to ensure the highest level of safety and productivity for underground personnel.

Jan 1, 2016

By Jaroslav Vicek, Alois Adamus

In the Czech Republic nitrogen was first used for the fight against the mine fire in 1949 (Hajek,1969). In the years 1949¬1996 the consumption of nitrogen in the Ostrava-Karvina Coal Basin /OKB/ reached more than 220 mil. m-3. The main source of nitrogen in the OKB is a central pipeline now. Gas nitrogen is used for the prevention of spontaneous combustion in gobs of longwall faces. The nitrogen infusion technology (Froger,1985), often called "franca technology", has been applied in the Czech coal mines since 1982. The aspects of the nitrogen infusion technol¬ogy can be theoretically solved by the calculation of mixing two gas streams in the filtration space. Longwall faces are parts of the ventilation network of the coal mine. The intake airflow of the longwall face is divided into the airflow passing through the face and a part of air losses passing through the gob. Air leakages through the gob and nitrogen in¬jected into the gob mix there. There is the main problem to solve air leakages in the gob. Usually, the principles of the gob aerody¬namics were used by many authors (Glusberg,1988;Voracek, 1994; Sulkowski,1993; Michailov, 1995; Dziurzynski, 1995; Kolarczyk, 1995; Saghafi, 1995; Sedlaty, 1993) that are applied to our case as well.

Jan 1, 1997

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize productivity, the influence of reclamation parameters must be well understood ? which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass appraisals, and also the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, we use biomass production experimental plots on reclaimed mine sites established by the Powell River Project (PRP) for a comparative study between satellite measurements of Normalized Difference Vegetation Index and inventory estimates of biomass under a variety of conditions. The PRP is a unique public-private partnership in the coalfields of southwestern Virginia dedicated to enhancing beneficial use and environmental protection of mined lands.

Feb 27, 2013

By Éder Domingos Oliveira, Carlos Antonio Morais, Ruberlan Gomes Silva

The objective of this work was to assess the influence of parameters such as residence time, solid content, and temperature in a process route towards purified rare earth liquor which could be adequate to produce marketable rare earth products. The steps of the process route proposed in this study comprised water leaching of a sulfated rare earth ore and removal of impurities through the purification of the rare earth sulfuric liquor, which is the product of the water leaching step. The sample used in the water leaching experiments was a sulfated rare earth ore produced by the reaction of a beneficiated rare earth ore with sulfuric acid followed by roasting at 700 °C for 2 h in a muffle furnace and cooling at 20 °C. The water leaching experiments showed that the best condition comprised a residence time of 30 min, temperature of 20 °C, and solid content of 10% w/w, resulting in a recovery of 71.3% of the rare earth elements (REE) and a lower impurity extraction, e.g., only 15.0% of Fe, representing the main impurity in the rare earth ore. Even when presenting low amounts of impurities, the rare earth sulfuric liquor still needed to be purified before it can be used in the production of marketable rare earth products. In the study, the rare earth sulfuric liquors were purified in two consecutive neutralization steps, first by dosing the limestone pulp to pH up to 3.5 and secondly by adding the lime pulp to raise the pH from 3.5 to 5.0. The application of two consecutive purification steps at 20 °C resulted in the highest overall REE recoveries (65.4%) throughout all the steps of the process, being 71.3% in the water leaching, 99.6% in the partial purification with limestone pulp, and 92.1% in the purification with lime pulp at 20 °C. Under this condition, there was a total elimination of Fe, P, and Th and a significant reduction in the Al, U, and sulfate concentrations in the purified rare earth liquor. The purified rare earth liquor attained through the experiment is expected to be amenable to be used in the production of marketable products due to the lower impurities/REO mass ratios.

By James L. Hendrix, Michael R. Straka, Emil B. Milosavljevic, Ljiljana Solujic, Neil P. Gallagher

Analysts that utilize the classical distillation procedures for cyanide analysis are often frustrated by the poor reproducibility and repeatability of these techniques. Capital intensive business decisions and environmental management regulations are exas­perated by the fact that the EPA/ASTM approved cyanide deter­mination methods produce data of questionable quality. Reliable cyanide values are important in monitoring the effec­tiveness of the cyanide detoxification procedures. Efficiency and cost of gold and silver cyanidation recovery can also be improved by precise cyanide monitoring in the process itself.

Jan 1, 1996

By Robert W. Bartlett

Both hydrometallurgical and vapometallurgical processes often involve ores that have been previously ground and size classified. When the valuable mineral is substantially liberated, the chemical reaction is likely to occur on the particle surface and the particle core will shrink as the reaction proceeds. If the chemical reaction products are solid materials then a solid shell, usually porous, will form around the shrinking core. This is known as the core/shell or topochemical reaction model. Using a spherical approximation for the particles, equations have been developed to express the extent of chemical conversion of the particle, depending on which one of the following process or mass transport steps is rate controlling:1 (1) chemical reaction at the particle surface, (2) diffusion through the thickening reaction product shell or (3) mass transport through a boundary layer surrounding the particle. In a previous paper2 these equations were coupled with the Gates -Gaudin-Schuhmann equation 3 4 describing the distribution of particle sizes resulting from comminution of rocks and other brittle solids to develop reaction yield curves expressing the weight fraction of metal or other valuable component of the feed that was chemically converted as a function of residence time. This was done for (a) batch, (b) continuous plug flow and (c) continuous back-mix flow (continuous stirred tank) reactors or process vessels. To make the curves of general rather than special utility, the residence time (average residence time for back-mix reactors) was normalized to a dimensionless time by dividing by the time required to completely chemically convert the largest particle in the feed to reac-

Jan 1, 1972

By John W. Graham

To start my talk, I thought it might be helpful for us to define the term "aggregate", so I went to the dictionary. Webster has several listings under "aggregate", and I found the following: "1. A mass or body of units or parts somewhat loosely associated with one another." Well, I didn't like that term "loosely" so I read on. "2. Crystals of one or more kinds of mineral or rock fragments." That sounded better, but I still read on. "3. Any of several hard inert materials used for mixing with a cementing material to form concrete or mortar." That sounded even better, but it should be a little broader. So I would like to define "aggregates" for you as follows: "Hard, inert fragments of rock or minerals used alone or with cementing agents to form products essential to nearly all types of construction." Usually aggregates are sand, gravel, or crushed stone, but other minerals such as clay or shale can be heated and become aggregates. What are some of the construction uses? Well, we've already mentioned concrete, as used in streets and highways, sidewalks and parking lots, airports and all kinds of building construction, not to mention bridges and swimming pools, and docks and breakwaters, just to list some of the uses. Our way of life couldn't exist without concrete. And you can't have concrete without aggregates,

Jan 1, 1977

By John E. Tilton

During the past several years — much to the delight of producing firms and countries — copper prices have surged from under $1 to more than $3/lb. Anyone familiar with the industry also knows that since the early 1970s the long-run trend in real copper prices has been significantly downward. This sharp contrast between short-run and long-run trends raises the issue of the forces behind these developments. What has been driving short-run prices up and long-run prices down? Simple economics suggests that it is all a matter of supply and demand. When demand is rising faster than supply, prices will rise and vice versa.

Jan 1, 2006

By Michael A. Piepenburg

The East Side Access (ESA) Project will extend Long Island Rail Road (LIRR) into midtown Manhattan via 11 km of tunnels, a new terminal station and associated support facilities. In addition to the hard-rock tunneling currently underway in Manhattan, soft-ground tunnels in Queens will traverse beneath Amtrak?s Sunnyside Yard and Harold Interlocking, the busiest rail interlocking in North America. This paper details ESA?s coordinated approach to interfacing with both Amtrak and LIRR with regard to the planned tunnels, shafts and related construction beneath or adjacent to the operating railroads. This interface includes integration of railroad staff, extensive presentations, reviews and agreements with the railroads regarding settlement mitigation, real-time automated geo-instrumentation monitoring, ground improvement, and geotechnical/environmental controls.

By James P. Dorian, James M. Otto

The value of exported nonenergy minerals from the less-developed countries has increased substantially between 1970 and 1985, but their market share relative to world exports has remained stagnant. Of the top twenty minerals exporters, only four are developing countries. Production capacity in the developing countries is shown to be less sensitive to demand downturns than capacity in the developed countries. Two approaches to the management of cyclical minerals demand are given using examples from India and Papua New Guinea. The authors conclude that pro¬tective policies implemented by developing nations have, barring a few exceptions, relatively little impact on the chronic nonfuel minerals oversupply problem.

Jan 1, 1989

By James A. Hartlage

Work on the design of Kelex 100 was initiated several years ago at the Research Laboratories of Ashland Chemical Company. The effort was specifically directed toward the synthesis of an organic molecule which would strongly and selectively chelate copper ions in acidic solutions and form an oil soluble complex which would be stable in contact with an aqueous phase having a pH of approximately one. This publication describes efforts to establish data which could be used to estimate the economic utility of the new reagent. For helping to accomplish these ends, the author wishes to acknowledge the assistance of Mr. A. V. Henrickson of Hazen Research, Inc. for gathering a portion of the data presented here and to thank the copper companies who supplied leach solutions for studies described in this paper.

Jan 1, 1969

By H. Suharyono, R. Hogg

A laboratory investigation was performed on flocculation following the addition of polymer to slurries flowing through pipes and in-line (static) mixers. Results are presented showing the effects of flow velocity, pipe length, in-line mixer elements and the use of multiple addition points. Flocculation performance was measured by the settling rate and the supernatant turbidity. The effects of agitation and mixing time are shown to be generally consistent with the results of equivalent tests (both batch and continuous) conducted in stirred tanks.

Jan 1, 1997

The fundamental objective of mine plans are usually to maximize the mine profit by extracting ore at the lowest possible cost over the mine life while some technical constraints are satisfied. Since the costs associated with the operation of trucks and shovels as resources are significant, determining the optimum number and allocation of these resources is an essential issue. This paper presents a Mixed Integer Linear Programming (MILP) model to determine the optimum number of shovels and trucks required to meet the short-term plan?s goals. Also, the model takes into account the allocation of trucks and shovels to mining faces. This model minimizes operational costs, while attempting to meet the production demand and to satisfy technological constraints. This paper also analyzes the operations of trucks and shovels in an open pit mine using ARENA simulation software.

Jan 1, 2012