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By J. Diao

In order to understand the flotation kinetic behavior of coal and associated mineral matter, a detailed investigation was conducted in a 2-liter Denver flotation cell using three high sulfur coals at three feed sizes, minus 28. 100 and 200 mesh. Subsequently. the flotation products were sieved into different size fractions and analyzed for their ash and pyritic sulfur content in order to delineate the effect of particle size on the rate at which each constituent floats. The results were tested with several different flotation kinetic models and the best model for coal was then chosen. The flotation rate constant and the ultimate recovery calculated from a kinetic model were used to delineate the effect of particle size, collector (dodecane) and frother (MIBC) dosages on the flotation kinetics of coal, ash and pyrite.

Jan 1, 1992

By Andrew J. Petruska, Rik Banerjee

This study explores implementing a machine learningbased system to generate a 3D surface repre- sentation of the roof and support straps in the mine. Event cameras have been chosen for their performance in high-dynamic-range lighting conditions and for their low latency. To enable automated drilling and bolting, 3D vision using eventbased cameras has been developed. A ground-truth set is created using two, time-synced event cameras and a LiDAR camera. These sensors are used to construct a ground-truth dataset of corresponding event- camera images and surface maps from the LiDAR. The network is tested with stereopairs of event images and produces a depth image with ±5 mm RMS error on average across 1000 test images.

Feb 1, 2024

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By James M. Barker

The occurrence of borates and zeolites at Mesa del Alamo is well documented by McAnulty and Hoffer (1) and Lefond and Barker (2). Further investigation indicates the presence of priceite and meyerhofferite in addition to the howlite (1) and colemanite (2). Analcime occurs in addition to the clinoptilolite and phillipsite (2). The Mesa del Alamo area is about 200 !a south of Tucson, Arizona, and 13 km southeast of Magdalena, Sonora, Mexico, just south of the unpaved road to Cucurpe (Figure 1). The geology and mineralogy of northcentral Sonora is known only on a regional basis except for small areas mapped in detail during copper exploration. The study area is within the Basin and Range province of North America from which borates and zeolites are now produced in California. The borates and zeolites at Mesa del Alamo occur in geological environments similar to those of the Mojave and Death Valley regions of California (3, 4). Thus, a detailed exploration pro- gram in the Magdalena area could result in the discovery of economic borate and/or zeolite deposits.

Jan 1, 1979

By J. Mark Richardson

Steady-state flowsheet simulators for mineral processing plants have evolved to a current high level of utility and accuracy. Reliable, general-purpose, semi-empirical models now exist in nearly all unit operations categories particularly in the areas of comminution and classification. .These models, installed as user-selectable functions within the integrated frame- work of flowsheet balance-solver software systems, can be strung together to represent any plant configuration. In addition, CAD-like graphics, data reconciliation and model parameterization functions have become standard features of the current generation of integrated plant simulators. These advances have given engineers the capability to investigate many different plant scenarios while requiring a minimum of actual plant testwork. This paper describes a methodology and an integrated software package which are being successfully applied in a number of operating plants worldwide to predict plant performance under changing conditions. Those conditions which can be changed include effect-of ore type, feed size, water addition rates, equipment geometries and flowsheet modifications. By using data from actual plant optimization exercises in real mills, the paper illustrates and out- lines a technique which includes plant data collection, ore breakage testing, flowsheet simulation, model-fitting (parameterization), data adjustment and model experimentation. Brief descriptions of some unit operations models, such as autogenous mills and cyclones, are provided as examples of the current state of such models. Ore breakage testing and its relation to certain models is also discussed. Computer- generated size-distribution graphs, along with tabular data generated by the simulator, round out the presentation and serve to demonstrate the real- ism and accuracy of the models. The paper concludes with a partial list of cases where this technology has been successfully applied.

Jan 1, 1992

By P. D. Rao

Although phosphorus is a very important biogenic element, its concentration in coal is generally low. Phosphorus concentrations typically range from 0.001 % to 0.229% in raw coals of the contiguous 48 states. Some Alaskan coals in the Cook Inlet region contain horizons unusually high in phosphorus. A foot by foot analysis of deep drill core, containing 70 ft. of sub bituminous 'C' coal from the Beluga coal field, Alaska, showed certain increments contained as high as 17.03% P2O5 in the coal ash; 1.01 % P on a moisture-free coal basis. Crandallite has been identified by electron microprobe analyses as a phosphorus numeral in these coals. The authors could quantify calcium, barium, strontium and phosphorus concentrations from the coal attributable to crandallite. These high phosphorus coals provided a unique opportunity to study the association of phosphorus in coals using chemical fractionation for exchangeable cations and acid extractable elements. Since the source of high phosphorous horizons in Cook Inlet coals is attributed to volcanic ash, it is suggested that the profiles of acid extractable phosphorous concentration may be useful for coal seam correlations.

Jan 1, 1992

By E. Farrokh

CSM and NTNU models are among the most commonly used models in TBM performance evaluation. Due to increasing application of TBM in different tunneling conditions, modification became necessary for these models. Sensitivity analyses on these two models indicate that both models are very sensitive to machine characteristics. Analyses performed on CSM database for cutter load and penetration rate prediction indicate while the r-square of the CSM model is reasonably high for the predicted cutterload, the r-square value for the penetration is low. In order to increase prediction capability of CSM model for penetration rate the model was reevaluated using non-dimensional analysis and the original database of Colorado school of mines. NTNU model is evaluated using Monte Carlo simulation and regression analysis. The results of analyses indicate that the majority of the variation of the penetration in NTNU model can be explained by only three parameters. This might indicate that the effects of other factors are overshadowed and it is worthy to reevaluate NTNU model using original database and more updated statistical methods to avoid overlapping of different parameters correlations.

Feb 23, 2014

By Patrick R. Taylor

United States Antimony Corporation, at its Yankee Fork property in central Idaho, is currently using a combination of flotation, gravity-amalgamation, and concentrate cyanide leaching, silver sulfide precipitation, and activated charcoal loading to recover both silver and gold. Tine processes of flotation, milling, gravity concentration, amalgamation, concentrate leaching, sulfide precipitation and gold recovery via charcoal are discussed. The flow sheet illustrates the use of cyanidation as an alternative to shipment to a smelter.

Jan 1, 1984

By C. G. Anderson

Extraction of valuable resources from complex orebodies will become more common. This is obvious for two reasons. First, the cleaner and more readily processed ores have continually been depleted through centuries of mining. Second, new technologies have evolved for effectively handling complex ores. One of these new processes has been in place at Sunshine since 1984. Based on sulfuric acid oxygen pressure leaching with nitric acid as an oxidizer, this patented technology allows silver and copper to be efficiently recovered from a complex sulfide concentrate. As efficient as it is, this process represents novel technology found nowhere else on an industrial scale. As such, a research program was undertaken in 1989 to optimize this leach process and to better understand it. From this study, several potential plant improvements were found and recommended. As a result, two of these options, nitric acid replacement by sodium nitrite and concentrate regrind are now used in day to day operation at Sunshine. Patenting of these changes was recently accomplished (1). Thus, the development, perceived mechanisms, plant integration and potential applicability of this technology will be covered in this paper.

Jan 1, 1994

By William G. Kegel

Apart from a usable product and good 'mining conditions, the greatest asset for a profitable coal mining organization is an effective mine maintenance program. The first step in achieving this is to have good mechanics-or men who want to be mechanics and are interested in knowing more about the design and control of the machines in their charge. A good mechanic's knowledge and ability result from ambition, curiosity, and determination. Starting with these qualities, the aspiring mechanic can launch his career by learning all he can about mechanics, electricity, and hydraulics. Though the path is rough, the end result is rewarding. Mining machinery probably receives as much, if not more, abuse as any other heavy equipment in use today. Considering the conditions under which much of the repair work must be done, it is essential that the mine operator has the best men and tools to perform the work. Mining machines, from their inception, have utilized the electric motor; and down through the years of mechanization, this power source has undergone many changes to better adapt it to the job. The first motors used were direct-current (d-c) motors since d-c power was the most economical power source for mining at the time of early mechanization. These motors were large open-type machines which are seldom used in modern mining. Because of the mine environment, the d-c motor has been reduced in size to better suit the application in mining machines and is now manufactured with dust-tight or explosion-proof enclosures. The d-c motor is constructed with either (or both) series and shunt fields located on the stationary part of the motor (stator) and- an armature coil wound on the rotating part of the motor (rotor). Power is supplied to the armature by brushes which are held stationary and make sliding contact with the armature. The brushes requires regular and careful maintenance because worn or defective brushes will cause heat or arcing which can destroy the motor. D-c motors can be used as d-c generators when mechanical power is supplied to them by the rotating shaft. In the case of a locomotive, this principle is used in dynamic braking. The momentum of the locomotive drives the motor and generates d-c power. The power is regulated with resistors and provides opposition to the motion of the locomotive.

Jan 1, 1981

By H. C. Lautenschlaeger

Let's start with a bit of History. Before the advent of woven wire screen cloth or perforated plate as we know it today, screens or sieves, as they were called, were probably made by the Greeks or Romans around the year 150 B.C. Coarse openings were made from bamboo or other woven reeds or with holes punched in leather hides, while fine openings may have been made using hair from the long tails of horses woven with small openings. The first metallic woven wire screens were probably produced by the Germans in the 15th Century. All of these screening devices were, of course, hand operated. The first records of mechanically driven shaking screens are found in "John Smeathon's Diary of His Journey to the Low-Country" in 1775. He was the English Civil Engineer who built the famous Eddystone Light House and discovered the formula for making hydraulic cements. He described a screen the Dutch were using as a wooden frame on which woven wire was mounted. This box was inclined at an angle and hinged on the lower end. The upper or feed end was equipped with a pulley so they could raise it up, say 5" or 6", and then let it drop abruptly onto a sill or stop plate, thus jarring the material deposited on the woven wire through the openings. Material that was passed over the deck was scooped up and redeposited on the woven wire for rescreening. This was an early form of what is today known as a recirculating load.

Jan 1, 1983

By C. L. Lin

A PC image-based on-line coarse particle size analyzer has been developed to measure particle size distributions under plant situations where overlapped particles are being transported on a moving belt conveyor. Although previous testing had shown satisfactory performance of this image-based system for separated particle size measurements (the non-overlapped case), it was necessary to modify original algorithms in order to solve the overlap problem and make the system suitable for plant operations. On-site testing has been conducted at a large copper concentrator in the southwestern U.S. for further investigation of the overlap problem.

Jan 1, 1995

By D. S. Parasnis

The early beginnings of mining geophysics in Sweden can be traced back to the reign of queen Kristina in the 17th century. The mine compass, consisting of a freely suspended magnetic needle in a casing, was in use certainly by 1640 and probably earlier for locating iron ore deposits. Whether the mine compass was a Swedish invention or not is an unsettled question since the possibility cannot be overlooked that the celebrated Nürnberg compass-makers of the 16th century may have constructed it for the first time(1). Be that as it may, the mine compass was very extensively employed in Sweden for more than two centuries and met with spectacular success in locating magnetic deposits under shallow overburden. Occasionally the diligent prospector would even be rewarded with a pyrrhotitebearing sulphide deposit, as witness many old sulphide-ore pits and some mines still in operation from the 17th and the 18th centuries. The mine compass measured only the orientation of the Earth's magnetic field and not its strength. Although it was improved in construction and sensitivity over the ages, no great strides were made in magnetic prospecting after the initial discovery of the use of the compass until Gauss, omnipresent in 19th century physics and mathematics, showed with the assistance of Weber how the strength of a magnetic field could be determined.

Jan 1, 1975

By LINDSAY BOTTOMER, Tassos Grammatikopoulos, Massoud Aghamirian, MARK FEDIKOW

A master composite (Master Comp) sample was prepared from three pegmatite zones from the Zoro Dyke D1 for mineralogical analysis and heavy liquid separation (HLS). The mineralogical examination was conducted on a subsample that was crushed to approximately P80 = 600 μm. The sample consists of spodumene (10.5 percent), quartz (29.3 percent), plagioclase (29.0 percent), K-feldspars (21.3 percent), micas (5.1 percent), tourmaline (2.9 percent) and Fe-Mn-phosphates (0.1 percent). Liberation of spodumene (88 percent) and gangue minerals, including quartz (89 percent), feldspars (94 percent) and micas (83 percent), is very good at this P80 . The average lithium (Li) concentration is 3.7 percent in spodumene, 2,196 ppm in micas, 1,001 ppm in tourmaline and 115 ppm in K-feldspars. Spodumene accounts for 96 percent of the total Li in the sample. The mineralogical data indicate the potential to recover spodumene by flotation with minimal Li losses due to other Li carriers. The HLS was conducted on a subsample that was crushed to smaller than 6.4 mm, with the smaller than 600 µm fraction removed from this test. The HLS results indicate it is possible to produce a high-grade lithium concentrate, with close to 6 percent Li2O, after the rejection of iron silicates with magnetic separation.

What is your assessment of the mining industry as we near the end of the 20th century? As it always has, the industry is continually changing. The recent rate of change has been hectic. Many mining-related commodities are selling at low prices. These include gold, silver, copper, coal and soda ash, to name a few. Lower prices place pres- sure on mining companies to increase efficiency through productivity, down- sizing or mergers. The short- term effect of this situation may adversely affect the individual SME member. But the long- term benefit is to build a stronger, more productive and internationally competitive mining industry. In addition, most of these metals and minerals have been historically cyclical in nature, and prices will rebound.

Jan 1, 1999

By W. H. Davitt

One might ask why someone like myself, involved in the determination of taxes, should be speaking at a "cost engineering" session of a national engineering society. While it is true that taxes, especially income taxes, whether they be federal, state, or local, are not usually thought of as a "cost" of doing business, it is equally true that these tax costs do reduce the distributable profits just as much, as the cost of power, supplies, or labor. Therefore, the consideration given to taxes is often as important as that given to other costs. Hopefully yea will recognize that, within certain limits, taxes can be controlled to an economic advantage. That question may then lead to another question: What does the amount of taxes have to do with me? I'm an engineer or manager; not an accountant or a lawyer. If I may take a few minutes of your time, I might be able to present in a brief discussion some interesting facts that will provide the answers to those questions. My discussion will be directed mainly to Federal taxes. However, much of it will be applicable to state and local taxes, also.

Jan 1, 1973

By Felicia F. Peng

The plant data were collected from three streams around a dense medium drum for coarse coal cleaning operated at various volumetric ratio of medium-to-feed. The effect of the volumetric ratio of medium-to-feed (MF) and particle sizes on the performance criteria, g50 and Ep, of the dense medium drum. These measured data were adjusted and calculated for the yields and balanced relative density distributions by mass balanced method based on the statistic principle. These balanced data were then used to formulate the mathematical models of the separation distribution curves for the various feed size intervals. The correlation equations for the g50 and Ep as the function of inverse of the feed size, and MF and total throughput were established. A numerical algorithm utilizing the Secant method, based on the root searching principle, was developed for yield optimization and simulation of dense medium drum separation to improve the separation efficiency and hence the product yield. The relationships between the direct ash content and relative density of the particles in feed and the products were established and incorporated into the numerical algorithm for predicting the product quality.

Jan 1, 1996

By S. Bahrampour

One of the basic requirements for designing an optimized rock support for an underground opening is having reasonably enough geological information. It is often financially impractical to obtain detailed geological information about the rock surrounding the excavations. The geological and geotechnical information which are obtained during the construction phase are also usually inadequate and need periodic operation stoppage. Penn State University- J.H. Fletcher & Co. joint venture is to improve the existing instrumented roofbolter so that the 3D geological and geotechnical map of the rock mass surrounding the underground working can be generated real-time as the data is being collected. This information will also be used to design appropriate support for different sections of mines. In this paper, recent results in improving the performance of the measurement while drilling system will be discussed. Moreover, updates related to borehole probing methods for estimating the properties of the rock masses will be presented.

Feb 23, 2014

By Alan C. Richter

Introduction The East-West Gateway Coordinating Council is an organization of local governments formed in 1965 to identify regional problems and to formulate policies, plans and programs to resolve them. The major goal of the Gateway Council is to improve the quality of life for the citizens of the St. Louis Region. While East-West Gateway Coordinating Council is the organization I represent and it only deals with the St. Louis Metropolitan Area, you will find one or more similar organizations in each of our nation's urbanized areas. As a result, for illustrative purposes, I will use my organization to portray what is happening nationwide. For example, in order to eliminate duplication, the Council reviews local applications for approximately 100 federally funded programs in such areas as highways, mass transit, parks, water treatment, and sewers before they can be sent to the appropriate funding agency. The Council's varied functions place it in a unique position of receiving more and more responsibility for developing strategies of implementation of various environmental regulations. This is due to the fact that environmental control is a relatively new field and we, as a country, are relatively inexperienced. The resulting regulations and guidelines will depend, to a great extent, on what the general public is willing to accept in terms of controls and what price they are willing to pay in terms of taxes and increased costs. Land Use: Growth vs No Growth This is perhaps the most encompassing environmental issue. We, as a nation, are beginning to realize that land is a limited natural resource and that the way we choose to use 'this resource affects many other aspects of our lives--whether we can catch edible fish in the Mississippi, how much we pay for sewer services, if we can swim in a

Jan 1, 1977

By Levent Ozdemir

An extensive study involving laboratory testing and computer modeling has been performed to assess the technical and economic feasibility of utilizing the recently developed minidisc cutters on roadheaders for hard rock mining. The results show that heavy duty roadheaders fitted with minidiscs can excavate hard rock formations at acceptable production rates and cutter costs. This paper presents and discusses the results of this study together with the ongoing developmental efforts of this technology, which include laboratory testing of a roadheader cutting drum with minidiscs and full scale field testing of a machine in hard rock

Jan 1, 1995