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By P. Kolettas

The development of novel methods for the investigation of the subsoil contributes to the improvement of geotechnical research, enhances the obtained geotechnical characterization and may reduce the investigation cost by reducing the number of required tests. Non-destructive testing methods, performed either in situ (i.e. electrical tomography, seismic refraction, etc) or in the laboratory can provide initial data and perhaps estimates of rock/soil properties. This study focuses on the development of rock material properties and/or characteristics based on non-destructive laboratory testing of a number of stones, ranging from porous (bioclastic) limestones to impervious marbles. Seismic velocity measurements as well as attenuation signals were digitally recorded using a digital oscilloscope. Data were processed using a novel technique of spectral analysis available through special Matlab packages employing Fourier transform methods. More specifically, the NFFT (Non Equispaced Fourier Transform) transformation was applied to seismic waves traveling through the subsoil using the Autosignal program (by Seasolve) and the Specgramdemo program included in the Signal Analysis toolbox of Matlab 6.5 (Mathworks). Results indicate a definite relationship between the frequency content of the signal and the rock type as well as the degree of saturation of the specimen.

Jan 1, 2008

By R. K. Amankwah, E. K. Asiam

Changes in the thermal-oxidation behavior and other properties of gold-bearing waste activated carbon when milled in both a ball mill and a vibratory mill were investigated. It was found that significant changes occurred in the oxidation temperature of the vibration-milled waste carbon as a result of increases in surface area and mechano-chemical activation. The mechano-chemical action brought about modifications in the crystal structure of the waste carbon. As a result, the vibration-milled sample was completely oxidized at a temperature of 450°C. Thus, the study established that vibration milling is a better way of lowering the temperature of oxidation of the waste carbon. Furthermore, the gold was found to be concentrated in the ash and, when leached with cyanide for 20 hrs, the gold recoveries from a sample having a head grade of 2 kg/t was 99.5% for the vibration-milled sample and 82% for the ball-milled sample. The lower gold recovery for the ball-milled sample was attributed to sintering of the ash, which was caused by the higher temperature required for its oxidation.

Jan 1, 1997

By A. L. Muler

Since 1956, when Broadbent and Callcott 1 proposed to analyze breakage processes by matrix methods, several authors and their co-workers have proposed various models of grinding that, in principle, could lead to fully automated grinding circuits. In particular, Meloy and Gaudin2, Gardner and Austin3, Kelsall and Reid4, Neloy and Bergstrom5, Callcott and Lynch 6, and Draper and Lynch have, by either computer simulation or by experimental data, or by a combination of the two, verified that comminution is reasonably well described by at least two functions: a selection function and a breakage function. The stage concept proposed by Callcott and Lynch6 requires that a classification matrix be included to completely describe breakage in an open circuit rod mill. The purpose of this work, portions of which are herein described, is to accumulate sufficient information on the breakage characteristics of quartz and magnetite in an open circuit rod mill, so that several of the theoretical and experimental approaches proposed in the literature can be compared with each other. Data is being gathered to compare the experimental method used by Kelsall and paid against the stage approach of Callcott and Lynch.

Jan 1, 1968

By A. M. Al Taweel, V. K. Kasireddy

Intensive coal cleaning usually necessitates fine grinding of the feed in order to liberate inorganic constituents from the surrounding organic matrix. This however adversely affects the ability of flotation techniques to beneficiate coal. Such difficulties are mainly attributed to the increase of particle population density, the decrease in capture efficiency, and the greater tendency of inorganic components to report with the froth. A three-pronged approach was adopted in an attempt to overcome these difficulties. The aggregative flotation technique was used to reduce particle population densities and improve capture, while unconventional spargers were used to generate a wide range of bubble sizes. Use of unagitated flotation columns allowed for the maintenance of countercurrent flows in both the recovery and washing sections. The combined effect of these parameters enabled the recovery of 92% of the carbon content of coal having an average particle size of 20.5 µ m, while rejecting 85% of the ash. This was accomplished using 2 kg of fuel oil per tonne of coal in a column 2 meters high operating at 2-3 tph/m3, a capacity which compares favourably with conventional cells.

Jan 1, 1989

By F. P. Schwarz, A. J. Erickson, S. M. Weber

The Mount Hope stockwork molybdenum exposit, Eureka County, Nevada, occurs in a small igneous cauldron complex 32 to 38 mybp in age. The deposit is characterized by alteration zones and mineralized shells symmetrically distributed around multiple intrusives. For samples from the 25 000 meters of 1981-82 drilling, an appraisal of error in in-house sample preparation and in commercial assaying has been made. After splitting, drill core is crushed and reduced in volume (8:1 at 10-mesh, 8:1 at 70-mesh, 6:1 at 200-mesh) to supply 25 grams of 200-mesh pulp for replicate analyses. A 0.5 g portion of the pulp is used for dissolution and atomic absorption analyses. Factors which initially generated unacceptable data variances have been minimized by planning, repeat analyses, introduction of standards, and routine monitoring. Assuming that error between replicate assays defines a Gaussian distribution with its average ideally equal to zero, precision (from preparation including core splitting and analysis of 8400 pairs of molybdenum samples) is on the order of + 25%. The error distribution is not biased. Accuracy is approximately 4% lower than absolute as determined by replicate assays of commercially prepared samples.

Jan 1, 1992

By J. W. III Leonard, T. E. Wilson

In addition to coalbed thickness and basic coal quality data, coal drill cores can produce design data for coal beneficiation processes. To generate design data, a coal drill core should be reduced from its original cylindrical form to a particle size distribution and composition that represents (with the possible exception of top size) a raw coal process stream. Reducing a coal core with a crushing machine rarely accomplishes this representation. This investigation employs drop-shatter impact breakage followed by dry batch tumbling in a steel cylinder rotated about its transverse axis to characterize the core in terms of first-order and zeroth-order break- age rate constants, which are indices of the propensity of the coal to degrade during handling. To reduce composition variables and conserve difficult-to-obtain coal cores, the initial drop-shatter and dry-tumbling tests were done with synthetic cores. Then, cores from three coal beds, Illinois No. 6, Upper Freeport and Pocahontas No. 5, were tested. Comparison of a crushed drill core and a drill core prepared by drop-shatter and tumbling indicated that the size distribution and size fraction composition of the drop-shattered/tumbled core more closely resembled the plant feed.

Jan 1, 2000

By R. W. Smith

A number of investigators have studied the electrokinetic potential (?) of kaolinite as a function of pH. (1,2,3,4,5) These investigators all agree that the ? is negative except at quite acid pH values. The actual shapes of the curves reported by the several authors vary considerably. In spite of the general negative character of kaolinite the mineral has a rather high anion exchange capacity. (6,7,8) The cation exchange capacity is the lowest for the clay minerals. (6) It has been shown that anionic surfactants adsorb readily onto the mineral even up to neutrality, often in quantities exceeding the reported anion exchange capacity. (7,8) At least part of the anionic adsorption should be onto positive edge sites thought to exist on the mineral. (9,10) In the present study ? of kaolinite was measured as a function of pH using both the streaming potential (sp) and microelectrophoresis (m.e.p.) methods. In addition ? was measured at various pH values as functions of sodium dodecyl sulfate (SDS) and trimethyldodecylammonium chloride (TMDAC) concentrations. In some experiments decyl alcohol (DA) was added.

Jan 1, 1968

By Thomas F. Martin

Contract 75-124-211 extends along the Chicago River from Roosevelt Road on the south to Ogden Avenue on the north. In addition a branch tunnel runs east from approximately mid-project ending near Lake Michigan. The contract was bid on December 14, 1977 with three joint-ventures submitting bids. Of these the joint venture of J.F. Shea Co., Inc. Walnut, California, (Sponsor), Peter Kiewit Sons' Co., Omaha, Nebraska and Shea Company and Associates, Walnut, California was low with a bid of $101,976,680.00. The MSD awarded the job to the Joint-Venture on January 5, 1978 with a scheduled completion date of January 23, 1983. The project consists of the following major items of work: (1.) A 25'-0" minimum diameter Construction Shaft, 220 feet deep (2.) 13,726 Linear Feet of 30'-0" Concrete lined Tunnel in rock (3.) 6,648 Linear Feet of 13'-0" Concrete lined Tunnel in rock (4.) Seventeen concrete lined Drop Shafts varying in finished diameter from 4'-0" to 12'-0", and each approximately 250 feet deep with chambers and connections to the tunnels varying from 100 to 1300 feet in length.

Jan 1, 1979

By S. Kesler

Rössing Uranium Limited has operated since 1976 a large open pit uranium mine and extraction plant at a remote site in the Namib desert, South West Africa/Namibia. The geology (Berning, I., et al. Economy Geology) and the technical aspects concerning mining, grade control and metallurgy have previously been described (Rössing Uranium, Mining Magazin and Whyllie, R.J.M. "Rössing Uranium reaches rated production", World Mining). The improvement of leach 'extraction has been reported in 1984 (Kesler, S.B. et. al. "Uranium extraction at Rössing") and the installation of a central process control system has been described (Kesler, S.B. et al. "The introduction of a central process system at Rössing"). At the beginning of 1983 a decision was made to develop a computer system for metallurgical plant optimisation which included mass and volumetric balances, analytical assays for up to 5 chemical elements and the costs for the major consumables. Within 10 months this computer system was developed and implemented. A large number of test runs were made and computer studies were undertaken. The metallurgical division now has a scientific tool for production; planning for actual comparison with plant results and for strategic investigations and decision making.

Jan 1, 1986

By M. Yavuz

The use of natural stones like marble is approximately as old as the emergence of human. Marble and natural stone usage of Turkey also dates back to very old times. Marble is produced in Anatolia since the ancient times. The archaeological excavations made in Anatolia indicate that the modern methods that are used for the production of marble blocks in modern world were first used by Anatolian people. Turkey is one of the oldest natural stone producers with its 4000 years of production history, starting from the Marmara Island. Therefore, the territory of Turkey possesses 4000 years of natural stone processing technology and experience. Turkey has fairly richer reserves of marble compared to other countries. This is why the rich and quality marble deposits of Turkey are resembled to the appearance of the Alpine-Himalayan marble belt of the world. Turkey has almost 40% of the total marble reserves (13.9 billion tones) of the world with 5.2 billion tones. Turkey?s marble reserve?s monetary value is worth about 2 trillion dollars. However, only 1% of these reserves are currently being utilized.

Jan 1, 2011

By Yixian Zhao

Although many ultimate pit limit design algorithms have been developed for the past one- quarter century, only the well known Lerchs-Grossmann's (LG) algorithm is capable of producing a truly optimum ultimate pit limit today. This paper presents a graph theory oriented algorithm for optimum ultimate pit limit design. This algorithm produces a true optimal solution and maximizes the total undiscounted net profit for a given 3-D block mine model. The algorithm performs much better than the well known LG algorithm, in terms of the reduction in computation time and computer memory requirements. More importantly the new algorithm is easier to understand and implement than the LG algorithm. Specifically, this paper discusses: 1) the computer representation of arcs and the rules of arc generations which dictate the formation of trees in the graph, 2) the mechanism of joint support and re-allocation, 3) the properties, the general procedures of the algorithm, and the suggested specific steps to implement the algorithm, 4) comparison between the new algorithm with LG algorithm, and 5) some experience in implementation of the algorithm and two case study results.

Jan 1, 1992

By Hassan El-Shall, El-Sayed A. Abdel Aal

The major goal of this study is to decrease iron content in wet-process phosphoric acid. Reducing the amount of post-precipitated sludge in the acid is another important objective in this investigation. In order to achieve these goals, research efforts have focused on bench scale testing of an iron-chelating reagent to remove iron from phosphoric acid produced from South Florida high-iron and -magnesium phosphate concentrate, and plant testing using freshly produced concentrated acids for reducing the post- precipitated sludge. The data obtained in the above studies suggest that the addition point of the precipitating reagent is very important, as the precipitated iron compound has higher solubility at higher P2O5 concentrations. Up to 60% Fe2O3 removal efficiency is achieved depending on the amount of the reagent, concentration of acid used, and operating conditions. The addition of precipitating reagents to freshly concentrated phosphoric acid leads to a decrease of up to 84% in sludge volume percentage depending on acid type and clarification conditions. Decreasing the volume percentage of the sludge facilitates acid handling as well as decreases the adherent water- soluble P205 leading to lower total P2O losses.

Jan 1, 2002

By William D. Hanson

Celestine (celestite) (SrSO4), the primary ore mineral of strontium, is present in the DeQueen Limestone Member of the Trinity Group (Lower Cretaceous) in Sevier, Howard, and Pike Counties, southwest Arkansas. Two mappable celestine beds have been identified. One bed is commonly 3-5 in. thick, but ranges up to 18 in. in thickness; the other bed is generally 2-3 in. thick. The beds are concordant within the DeQueen Limestone and were formed by precipitation from periodically restricted sea water. Reports concerning celestine date back to 1929, when Hugh D. Miser and A. H. Purdue mapped the geology of the DeQueen and Caddo Gap quadrangles. A small amount of celestine was produced in the early 1940s in Howard County. During 1941, the J. W. Hintze Company collected 1,500 pounds of celestine for testing purposes. In 1942 and 1943,750 test holes were drilled by the Bennett-Clark Company in Howard County. Afterward, approximately 90 tons of celestine was open-pit mined and shipped to Texas for processing. Since then, no mining of celestine in Arkansas has taken place.

Jan 1, 1999

By S. C. Lamey, P. A. Hesbach

This study evaluated the use of regionally produced coal combustion products to neutralize and remove metals from acid mine drainage (AMD). Synthetic AMD mixtures were treated with a number of fly ashes and fluidized bed combustion (FBC) ashes. All of the ashes reduced the volume of the sludge produced and gave a faster settling rate than the sludge produced by treatment with lime. Faster settling allows greater throughput rates. In addition, the FBC ashes, which generally contain alkaline components used for sulfur capture, completely neutralized the acidity and, if desired, raised the pH above 10. The fly ashes, on the other hand, reduced the final volume of sludge but required additional neutralizing agents to attain a pH >5. The pH of the AMD can be taken to above 10 to insure complete removal of manganese, or it can be taken to a more neutral pH of 7 or 8 to allow for the safe introduction of the aqueous phase into ponds or streams. The process combines two industrial waste products to reduce the disposal volume of one of the waste products and to produce an environmentally safe aqueous discharge.

Jan 1, 2002

By S. S. Cook, S. E. Paulson

The US Bureau of Mines is conducting core leaching experiments with sulfuric acid on oxide copper ores from the Cyprus Casa Grande and Asarco/Freeport Santa Cruz deposit in Arizona to further the understanding of the leaching process in supergene copper ores as it relates to in situ mining. Leach solutions from atacamite mineralization contained 5 to 30 g/L (0.05 to 0.28 oz/gal) copper and few extraneous ions. Leachant from chrysocolla ores, with grades similar to the atacamite, contained 2 to 9 g/L (0.02 to 0.08 oz/ gal) copper and abundant extraneous ions. Quartz and K-feldspar had no impact on leach solution composition at any acid concentration up to 40 g/L - (0.39 oz/gal) while illite and sericite had minimal impact. Biotite, calcium-rich clay, and limonite have a significant impact on solution chemistry when there is abundant free acid in solution. High acid concentra¬tions increase acid consumption in ores with abundant biotite and limonite gangue. High acid concentrations can be used in ores with quartz, K feldspar, and sericite gangues without increasing acid consumption per unit of copper removed.

Jan 1, 1990

By Gregg J. Hodges

The Stillwater pt-pd mine and flotation mill are located about 130 km (80 miles) southwest of Billings in Stillwater county, M6ntana~ The pt-pd ore zone stretches about 43 km (27 miles), but varies in thickness from 0 to 6 meters (0 to 20 feet, but generally 3-6 feet) and dips 55-90,degrees from horizontal. The ore is hosted in basic, layered igneous rocks containing about 1% sulfide minerals which include chalcopyrite, pentlandite, pyrrhotite, and minor pyrite. The pt-Pd minerals are intimately associated with these sulfide minerals and are found as precious metal sulfides, tellurides, bismuthnides, and arsenides as well as native Pt metal. Approximately 90 different precious metal minerals have been found, but about 80% of the pd is in solid solution in the pentlandite. The ore assays about 0.1% Cu, 0.1% Ni, 6.2 g Pt/tonne (0.18 Troy ounce Pt/short ton (opt)), 21.3 g Pd/tonne (0.62 opt Pd), 0.21 g Au/tonne (0.006 opt Au), and 0.21 g Rh/tonne (0.006 opt Rh). The ratio of pd to Pt in the Stillwater ore and concentrates is about 3.5.

Jan 1, 1988

By Douglas Castleberry

The degree of fragmentation obtained in primary quarry blasting has always been a factor in the speed of digging' the muckpile This paper will discuss a case history of increased production and associated lowered costs from increased fragmentation. The quarry under discussion is fairly new, located in Georgia, and is in the large operation .category. Loading is done by three yard shovels, and, primary crushing by a 48" x 60" haw crusher preceded by a 5' wide feeder. The stone is a hard granite gneiss, of Los Angeles rating 22, and apparent specific gravity is 2.68. The product is shipped to points in that state for railroad ballast, concrete aggregate, and road building stone. Inasmuch as fairly large shovels and a large Jaw were to be utilized, initial drilling and blasting were pointed toward producing fairly large sized muck for this large equipment. This was following a concept somewhat in vogue for some years in the Southeast wherein many large equipment plants would tend towards larger fragmentation, and smaller equipped plants would conversely tend toward attempts at smaller sized rock piles for smaller shovels and crushers.

Jan 1, 1960

By W. S. Fyfe, G. Southam, T. J. Beveridge

Sporosarcina ureae was able to grow in the presence of tip to 10-ppm L-asparagine complexed gold. However, 10 ppm Au3+ was found to be highly toxic to Sporosarcina ureae, killing 109 bacteria/mL within a few seconds. To compare the effects of these responses on gold mobility, an in vitro bacterial biofilm model was developed to examine the interaction be¬tween Sporosarcina ureae and ionic gold or L-asparagine gold complexes in gravity fed columns. The immobilization of ionic gold was between 80% and 90% over a period of one week. But, as the available cellular reactive sites became saturated, immobilization decreased to 14% within two weeks. In the L¬asparagine-gold system, gold immobilization in the cytoplasm occurred at a high rate (80% to 90%) throughout the experi¬ment, with limited toxicity towards Sporosarcina ureae. The bacterial immobilization and detoxification of L-asparagine¬complexed ionic gold was associated with a low molecular weight, i.e, <5,000 dalton (atomic mass unit), intracellular protein fraction. This peptide-complexed gold would allow for the continued biogeochemical cycling of gold under ambient (<100°C) surface or near-surface conditions.

Jan 1, 2000

One of the major objectives of cost analysis is to enable the manager to predict the financial outcomes of decisions. To accomplish this, the future costs and benefits of alternative courses of action must be determined. If care- fully used, information about past financial performance can be helpful in this analysis despite the fact that, by definition, financial reporting information is historical. In many cases, both revenues and costs need to be estimated for decision- making. For the production manager, additional revenue is a result of increased throughput or recovery of valuable material from the stream of mined material. A reduction in operating cost, although similar to a revenue increase in its financial impact, is estimated using slightly different techniques. Generally, the estimation of cost is more difficult than the estimation of revenue. Most cost estimates have two components: an estimate of fixed costs and an estimate of variable costs. As discussed in chapter 5, the total cost of an activity during a specified period can be expressed as: Total cost = (Variable cost per unit of activity) x (Units of activity) + Fixed cost or TC = VX+F

Jan 1, 1999

By Gerald G. Griswold, James O. Greenslade, Cherie Tilley, Richard Reseigh

INTRODUCTION The Harrison Western Corporation, a leading Denver based mine contracting and engineering concern, is presently engaged in sinking two 1,006 m (3,300 ft) shafts for the Phillips Uranium Corporation at their Nose Rock Project, approximately 13 miles northeast of the small community of Crownpoint in McKinley County, New Mexico. The Nose Rock Project is the first attempt by the Phillips Uranium Corporation to tap the deep uranium reserves in what has become known as the Grants Mineral Belt. (See Figure 1) Project Description Phillips Uranium Corporation&apos;s plan for the large 2700 metric ton per day (2950 tons/day) mining facility calls for a series of deep access and ventilation shafts ranging from 4.27 m (14 ft) to 5.49 m (18 ft) in diameter to approximate depths of 1,006 m (3,300 ft). The initial pair of shafts consists of one production shaft and one ventilation shaft separated by a distance of 91 m (300 ft). The interbedded layers of sedimentary sandstones and shales to be penetrated by the shafts contain several major water producing aquifers, the deepest being the mineralized zone called the Westwater Canyon Member of the Morrison Formation.

Jan 1, 1981