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By Donald W. Gentry

The evaluation of industrial minerals deposits for investment decision making follows the same basic principles that apply to metallic deposits. For example, the quantity and quality of the mineral occurrence is assessed, engineering/economic feasibility studies are performed for various production scenarios, project evaluation criteria are calculated for each alternative, and finally, an investment decision is made. A more specific evaluation-related example of commonality between metallic and nonmetallic deposit assessment relates to the various parameters which impact project feasibility studies. There exists a suite of pertinent factors which must be considered, studied, and analyzed when evaluating any mining property. Table 1 is an outline of some, but certainly not all, of the various factors which should be considered when preparing feasibility studies on mining properties. Most analysts agree that all the factors listed in Table 1 should be assessed to some degree in at least one of the feasibility studies prepared during the property's evaluation period.

Jan 1, 1984

By Paul H. Johnson

A new system for leaching many types of ores has recently been developed on a commercial basis by J and J Research and Development, Inc. of Hanover, New Mexico. This revolutionary new leaching system consists principally of three new leaching reactors; viz, (1) a large, air-agitates, column-like reactor for leaching crushed ores that is constructed in an underground environment and has the inherent ability to do a very efficient job of leaching, (2) a vat-like, air-agitated vessel for leaching an rinsing finely ground ores and , (3) an air-agitated copper precipitation column that is built underground and utilizes an inexpensive dense or heavy scrap iron as a copper precipitant. Each of these new reactors have been used in a large leaching plant near Hanover, New Mexico.

Jan 1, 1973

By Missy Isaman

"Mixed ground tunnels come in all kinds. In rock tunnels with possible faults and high pressure water, the challenges are many. With the advent of Crossover TBMs, contractors can minimize machine wear in such conditions while maximizing efficiency. The newest generation of Crossover is exemplified by two projects in Albania and Turkey. A 5.56 m Crossover TBM destined for Turkey’s Gerede Water Transmission will be assembled using Onsite First Time Assembly (OFTA) from within an existing tunnel. The unique machine will bore through 30 fault zones requiring the TBM to be sealable to up to 20 bar so pre-consolidation grouting can be done. If boring under pressure is required, the TBM will bore sequentially using the screw conveyor fore and aft gates. Skewing further towards hard rock, a unique 6.2 m diameter Double Shield TBM with Crossover features was designed for Albania’s Moglicë Headrace Tunnel. The machine features closure doors and a sealing system to contain inrushes of water until they can be grouted off. This paper will discuss the unique aspects of the Crossover designs, including their inception as based on past projects in difficult ground, and their utilization at the two current projects. INTRODUCTION Specialized tunnel boring machines have been made for years to tackle specific types of ground conditions. Traditional types of TBMs bore within a specific set of ground conditions. If a project is located in a competent granite face, then a Main Beam machine is a good solution. In soft ground, Earth Pressure Balance (EPB) machines are the method of choice. Years of experience and engineering advancements have made both types of machines fast and economical solutions for tunneling. Unfortunately not all ground conditions are a perfect swath of one material, and the need for a more diverse machine is apparent."

Jan 1, 2016

By Ted H. Eyde

Both private industry and the Interior Department have become alarmed about the enormous amount of Federal land that has been withdrawn from appropriation either under the Mineral Leasing Laws or the Mining Law of 1872. According to a recent article by Gary Benethum and L. Courtland Lee, governmental actions have withdrawn nearly 400 million acres from the operation of the Mining Law of 1872 and over 500 million acres from the Leasing Laws. An addition al 100 million acres for the Mining Law of 1872 and 70 million acres for the Leasing Laws are either encumbered or being managed in such a way as to constitute a defacto withdrawal from mineral development. This means simply that mineral exploration end development under the Mining Law of 1872 is either prevented or discouraged in an area the size of the states of California, Arizona, Washington, Oregon, Nevada, Utah, Idaho, and one half of Colorado combined. Under the Mineral Leasing Laws, exploration and development is either prevented or discouraged in an area equal in size to all the states east the Mississippi River, except Maine.

Jan 1, 1976

By B. Yarar

Samples of coal from an adit in the Fording River District of British Columbia showed hydrophilic properties between depths of 0-24.5 meters and was naturally hydrphobic at higher depths. Laboratory experiments indicated that weathered samples (i.e., those mined at 0-24.5m) could be upgraded by froth flotation at pH<2 following slimes removal. The i.e.p. of samples varied regularly between pH=1.6-4.1, the weathered fractions being at the lower end of the pH scale. These values followed a pattern comparable with the flotation behavior of samples. A patchwise structure for coal surfaces determining the resultant disjoining pressure, which in turn determines flotation-non flotation relationships is postulated.

Jan 1, 1982

By J. J. Komadina

Since the advent of resin-in-pulp (RIP) technology for treatment of uranium-bearing ores in the 1950?s to current carbon-in-pulp (CIP) processing of gold values, metallurgies and operators alike have wrestled with the problem of interstage screening. Early gold CIP plants such as at Homestake utilized externally mounted vibrating screens in conjunction with air lifts to effect carbon-pulp disengagement. Other operations world-wide have likewise adopted this technique with varying degrees of success. Subsequent development of in-tank launder screens both in South Africa and the United States have been of the air cleaned variety (EPAC)

Jan 1, 1988

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

The objective of this study is to assess the impact of different reagents, such as limestone, lime, magnesium oxide, and sodium hydroxide, in experiments carried out in the single purification step and in two consecutive purification steps by raising the pH of a rare earth sulfuric liquor with the aim to remove or reduce the impurity concentrations in the rare earth sulfuric liquor. The choice for the best purification condition was made based on the minimum loss of rare earth elements (REEs), reagent consumption, and residue generation. The exploratory experiments show that it takes place in the two consecutive purification steps, the first one consists in dosing the limestone pulp until it reaches a pH of 3.5 followed by an addition of a lime pulp reaching a pH of 5.0. Under this condition, the results were a total removal of Fe3+, PO4 3− , and Th4+ ions and a reduction of 99%, 87%, and 37% w/w in the Al3+, UO2 2+, and SO4 2− concentrations, respectively, in the purified rare earth liquor. Furthermore, the lowest REE losses (8.3% w/w) and reagent consumption (4.3 kg/m3 ) and also a low residue generation (7.5 kg/m3 ) were observed in this condition. Despite reaching similar results regarding impurity removal, the experiments done with the addition of limestone, lime, magnesium oxide pulps, and sodium hydroxide solution in the single purification step, where the pH was raised to 5.0, presented higher REE losses (64.9%, 42.5%, 44.8%, and 60.9% w/w, respectively) and a higher residue generation (43.2, 25.1, 11.1, and 13.6 kg/m3 , respectively). This occurred due to the co-precipitation of salts containing rare earth elements in their composition. The experiments conducted with limestone, lime, and MgO resulted in a higher consumption of reagents, while the same result was observed when NaOH was used (4.3 kg/m3 ). In the experiments carried out with the addition of magnesium oxide and sodium hydroxide, the respective purified rare earth liquors presented a high concentration of magnesium, sulfate, or sodium, which could impact the quality of the marketable rare earth salts, whereas the salts obtained under the best condition observed in this study seem to be amenable for use as raw material in an attempt to obtain rare earth products with an acceptable chemical quality.

By Stig Premfors

Lamco Joint Venture is operating a Dravo Pelletizing machine to produce pellets from the natural slimes of an earthy hematite ore. The grate area of the machine 3.3 x 106 m equal to 350 m2 (3800 sq. ft.) and the installed fan capacity is 8200 HP. The limiting factor for production is normally fan capacity. This means that the processing fans can not pull the additional air (i.e the additional calories or BTUs) through the bed which would be required for increased production. A way to increase production without major modifications is to supply the additional calories needed for increase production by adding coal to the pellet feed. After successful laboratory tests following method of coal addition has been chosen and the following results have been obtained. 1. The ground coal is added to the slurry prior to the filters and the rotary dryer. 2. By adding 0.6% coal, an increase of about 15% in production rate has been obtained. 3. No significant changes of metallurgical properties have been observed (i.e. tumbler index, compressive strength, ferrous iron content, reducibility, Linder degradation and swelling). 4. No unexpected operation problems have been experienced. The pellet discharge temperature increases and is the limit for how much production can be increased by coal addition without making plant modifications.

Jan 1, 1971

By Edmund H. Warner

Any city dweller who has walked alone along a remote mine passageway has to be impressed by the eerie silence - the total absence of noise except for ones own breathing and scuffing of boots on the bottom. An underground mine can have tremendous contrasts, from complete silence to the ear piercing clatter of percussion drills working on the mine roof. Noise in underground mining machines is both useful and detrimental. Without characteristic noises that are recognizable to miners, operators would have a more difficult job operating their machines. Noise serves as a warning of approaching machinery, and changes in noise give indication that breakdowns may occur. But excessive noise is a health hazard. In recognition of this fact, our Congress included noise exposure as a part of the "Coal Mine Health and Safety Act of 1969". As Fig. 1 indicates, allowable noise exposure is established by specifying a time duration permitted at different noise levels. This is the well known "Walsh-Healey" criteria which governs noise exposure in many industries.

Jan 1, 1977

By Maurice L. Madden

An investigation was undertaken for a ground water discharge plan for the Chino mining complex near Hurley, New Mexico. Operations which impact ground water include dump leaching, storage reservoirs, and tailings seepage. The investigation included both hydrogeological data collection and laboratory analysis. A conceptual understanding of surface water and ground water was then developed. Surface water and ground water models were used to match existing conditions and predict the impact of operational modifications. The study concluded that runoff and resulting leach reservoir overflows were primarily responsible for the ground water degradation. Tailings seepage represents a smaller part of the impact.

Jan 1, 1984

By Yang Zhao, Wanping Wang, Siqing Liu, Shuming Wen

"In China, most reserves of rich iron ores have now been depleted and sustainable development of low-grade iron ores has become a critical discussion topic in the mining industry today. The aim of this study was to evaluate the applicability of beneficiating a low-grade, hematite-magnetite ore (assaying 18.64% Fe) for subsequent utilization. In this study, process mineralogy and beneficiation of the ore were carried out in the laboratory. First, mineralogical investigation shows that the main metal minerals are hematite, magnetite and a little octahedrite that cannot be used at present, and the main gangue minerals include albite, quartz and ankerite. Based on the above, a combined process of magnetic separation and gravity concentration has been developed by using laboratory low- and high- intensity magnetic separators and a slimes shaking table, respectively. Factors affecting these separation methods are discussed, including process mineralogy on the tailings of the high-intensity separator, where the iron minerals were found to be finely disseminated in the gangue as inclusions. By applying a two-stage grinding step and a magnetic separation stage together with gravity concentration, a marketable iron concentrate assaying 60.79% Fe at a recovery of 60.23% can be obtained, when the feed assays 18.75%Fe, which provides some useful information for the sustainable use of low-grade iron ore.IntroductionIron is the world’s most commonly used metal. Steel, of which iron ore is the key ingredient, represents almost 95% of all metal used per year, primarily in structural engineering applications and for maritime purposes, automobiles and general industrial applications. By the end of 2009, the iron and steel production in China ranked the first in the world, and reached 0.567 and 0.537 billion tons, respectively. The domestic supply of iron ore was 0.88 billion tons and about 0.628 billion tons of iron ore were imported in 2009."

Jan 1, 2015

By W. Hitchcock

To enable the analysis of stability for a mine feasibility study a variety of geotechnical engineering parameters need to be obtained. At the early stage of a project it is usual for those responsible for the study to require a wide spatial distribution of RC holes in order to define a resource at the lowest possible cost. By the time a geotechnical study has commenced drilling priorities have usually switched to improving the definition of a resource, by drilling with diamond coring methods in the central area of the main orebody. The usual timing for geotechnical data collection is therefore after a wide distribution of holes have been drilled but which contain little geotechnical information. Conventional methods employed usually involve estimation methods, including book values and examination of disturbed core, or expensive additional drilling. With downhole geophysical methods we can economically take advantage of existing holes to obtain continuous values for density, defect orientation and ranking, elastic modulus values, unconfined compressive strength estimates and fracture frequency. This paper presents the results of a geophysical study and discusses the advantages and potential pitfalls of the method as compared to conventional methods of data collection.

Jan 1, 1999

By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By T. E. Wilson

An exploration bore core sample of coal ought to be reduced from its original cylindrical form to a particle size distribution and particle composition that reflects, insofar as possible, a process stream of? raw? coal it represents. Often, coal cores are reduced with a laboratory crushing machine, the product of which may not match the raw coal size distribution or size fraction composition. This study employs drop-shatter impact breakage followed by dry batch tumbling in a steel cylinder rotated about its transverse axis in order to characterize the core material in terms of first-order and zeroth-order breakage rate constants. These are indices of the propensity of the coal to degrade during excavation and handling. Initial drop-shatter and dry tumbling tests were done with synthetic cores, to reduce material variables and . conserve difficult-to-obtain coal cores.? Cores of three different coal beds --Illinois No.6, Upper Freeport, and Pocahontas No. 5 -were subjected to drop-shatter and dry batch tumbling tests to determine breakage response. Comparison of coal preparation plant feed with a crushed bore core and a bore core prepared by drop-shatter and tumbling (all from the same Illinois No.6 coal mining property) indicated that the size distribution and size fraction composition of the drop-shattered/tumbled core more closely resembled the plant feed than the crushed core.

Jan 1, 1998

By Weijie Wei, Jinwang Zhang, Shengli Yang

In longwall top-coal caving (LTCC) mining with an inclined seam, the recovery rate is low and equipment stability is poor due to the unbalanced top-coal drawing process. To address these problems, this paper proposes the dynamic group caving method (DGCM), whose basic premise is that when the drawn volume of top coal from a support reaches about half, the next support begins drawing top coal, and the drawing process between the two supports is half done. Using particle flow code (PFC), the caving mechanism of top coal under DGCM was investigated. The results are of significance to realize high efficiency and precise caving in LTCC mining with an inclined seam.

By R. L. Wiegel

A well-defined geometric model for a mineral system and its liberation by size reduction is used to show the relationship between true volumetric particle composition and the composition estimates obtained by the measurement of linear intercepts or areas of simulated polished sections of particles. Based on this information, a transformation is developed between the areal measurements and the volumetric composition for this idealized mineral system. Key words: Gaudin random liberation model, Mineral liberation, Particle composition measurement

Jan 1, 2010

By L. Cui

A new flotation collector, benzyl arsonic acid, was used for the flotation of ilmenite. ESCA, Auger spectroscopy, and chemical analysis were used to investigate the correlation between the variation in surface constituents and the flotation recovery of ilmenite. Experiments indicated that, as the ratio of surface Ti ions/surface Fe ions increases, flotation recovery increases. pH regulation with an inorganic acid was found to be effective in changing the ratio of surface ions, and, hence, the flotation recovery.

Jan 1, 1986

By Jr. Schnakenberg

The automation (robotization) of coal mining activities at the face offers improvements in worker safety and productivity. The evolutionary introduction of autonomous, intelligent robotic machines to perform the most hazardous tasks may become a reality within the next 10 years. The U.S. Bureau of Mines Robotics and Automation research program is aggressively pursuing the development of the enabling technology necessary to achieve this goal. This program consists of both core and applications research, each focused on the fundamental issues of robotic technology. In the short term, the research is directed specifically to the robotization of present-day underground equipment and is being performed in a manner that can make incremental improvements in safety and productivity. The long-term goal is the development of intelligent autonomous mining systems.

Jan 1, 1990

By G. R. Harrod

Effective mine operation demands that the right people have the right information at the right time. Caterpillar&apos;s Mining and Earthmoving Technology System (METS) meets this demand by providing "real-time" information transfer between the mine offices and machines equipped with the Caterpillar Computer Aided Earthmoving System (CAES). Transfers of mine plans from the mine planning software to CAES-equipped machines give operators access to current mine plans within minutes of their creation. Additionally, office personnel have access to a current digital terrain model (DTM) of the mine site as it is updated in "real-time" by CAES-equipped machines. METS provides mine personnel in operations, planning, and management the information they need when they need it.

Jan 1, 1998

By D. Lauriski, E. D. Thimons, A. C. Smith, D. C. Fredley

The National Institute for Occupational Safety and Health (NIOSH) and Northwest Barricade LLC (NWB) conducted a study to evaluate the effectiveness of a novel fire blocking gel for use in underground coal mines to extinguish or retard the growth of a coal fire. The gel agent was subjected to controlled laboratory testing to assess its ability to delay coal ignition. It was then evaluated to determine if manual fire hose application could be used to apply the agent to mine roofs and ribs to provide a safe egress for mine rescue teams from a fire area. The gel agent was also evaluated in a water sprinkler system to determine its potential for use in conveyor belt fire suppression systems. The agent was then tested in live-fire exercises to examine its effectiveness in retarding and extinguishing a deep-seated coal fire and wood fire. Lastly, the ability of a mine rescue team to quickly and safely apply the gel agent to a mine entry during a simulated mine fire exercise was determined.

Jan 1, 2011