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By L. Gertsch, R. Gertsch

Mechanical mining is steadily gaining usage in the mining industry. A variety of machines currently finds employment: tunnel boring machines, roadheaders, continuous miners, surface miners, and augers. These machines have advantages compared to drill and blast mining methods, including increased safety, lower cost, uniform muck size, and accurately sized openings. A century of experience with mechanical methods has already paid dividends to the coal industry. Current trends guarantee eventual development of true general-purpose hardrock mechanical mining machines. Mechanical miners will become integrated mining systems and will determine the design of mines, when several significant challenges have been met.

Jan 1, 2001

Rising energy costs are a growing concern among mine operators. At sur’ace operations, the size of a dragline, production requirements, pit geometry and layout, and operator skill are all factors in potential energy savings. The following tips are offered as a practical means to conserve energy demand, and can be applied to diesel fuel draglines as well.

Jan 7, 1980

By Drupad B. Desai, Bruce Chang, Jay L. Merritt

This paper reviews difficult ground conditions encountered along the alignment of large-diameter sewage tunnels for the City of Los Angeles. It offers a detailed one-of-a-kind solution to a unique problem for shallow urban underground tunnels in a seismic zone, using state-of-the-art materials, technology, and equipment. The following topics are discussed in detail: • Geotechnical Design consideration for tunnel traversing through an active fault zone. • Seismologist evaluation of possible fault-offset problems where a fault zone crosses the alignment, in the event of an earthquake of moment-magnitude 6.5. • Probability analysis regarding "recurrence interval." • Structural design of tunnel subjected to displacement, subjected to axial elongation or shortening, and capable of rotational freedom. • Special joint details.

Jan 1, 1989

By S. G. Malghan, J. P. Van Dillen

Introduction Some uranium minerals are paramagnetic and hence are amenable to concentration by high gradient magnetic separation (HGMS). This paper describes effects of the HGMS parameters-pulp velocity, field strength, matrix loading, and magnetic field gradient-on the product recovery and grade. Unsatisfactory separation of uranium minerals by HGMS is related to ore-specific properties, such as lack of liberation, fine dissemination of uranium minerals, uniform distribution of magnetic minerals throughout the ore matrix, and interference of fine-sized slimes. Experimental techniques to identify and resolve some of these problems are outlined. HGMS of Uranium Ores The mechanism by which uranium minerals are attracted to a magnetic field is either due to its magnetic susceptibility or its association with other minerals that are magnetic. Data on magnetic susceptibility of uranium minerals are scarce. The only reported data are for uraninite at 2360 X 10-6 cm3/mole. Povarennykh (Andres, 1976) concluded that the magnetic properties of minerals depend on: • Structure of the outer electron shell in a mineral with electropositive atoms; • Valence of the atoms; • State of the chemical bonds; • Type of coordination; and • Proportion of magnetic atoms (Fe, Mn, Cr, and Ni) in the composition of the mineral. However, information on the magnetic susceptibilities of the constituent atoms of a mineral alone does not suffice for evaluating the mineral compound as a whole. Most often, uranium minerals can be beneficiated by HGMS if they are associated with other minerals that are magnetic. This appears to be a more predominant mechanism by which the uranium minerals are beneficiated. Experimental A Sala-HGMS (Malghan and Subramanian, 1981), model 10-15-20, separator was used in the experiments. The matrix material-ferromagnetic stainless steel in the form of expanded metal or steel wool-was packed into a 38-mm (1.5-in.) diameter by 360-mm (14-in.) long canister. The matrix material occupied only a 150-mm (6-in.) length. The experimental set-up and slurry flow direction are described elsewhere (lannicelli, 1976). The response of uranium ores in the HGMS was studied by feeding well-dispersed slurry at 10% solids and examining the influence of process variables on selectivity and overall uranium recovery. The chemical and mineralogical characteristics of the ores under study are presented in Table 1.

Jan 12, 1983

By P. Ashayer, J. Curran

Introduction Rockfalls occur when rocks or boulders detach from mountains or hills and tumble down. They can pose significant hazards to infrastructure such as highways, buildings, and mine open pits, and they sometimes result in personal injury or death. Prediction of rockfalls is a difficult task. Slopes that are at risk of rockfall have highly variable geometries. The location, mass, and shape of the rocks that might dislodge and fall are uncertain. Moreover, the materials that make up a slope can vary considerably from one section to another. Furthermore, the relevant material properties are usually not well known. Performing probabilistic simulations of rockfalls, combined with proper statistical analyses, has proven to be an effective and acceptable method for dealing with these difficulties [1, 2, 3]. The movements of a falling rock can be classified as freefall, bouncing, sliding, toppling, or rolling. The falling trajectory is controlled mainly by the geometry of the slope, the block shape, and the energy dissipated at each contact of the block with the slope. A rockfall model is evaluated based on its ability to efficiently predict the velocity, frequency, height of bounce, and run-out distance of falling rocks. With this information, the engineer can design remedial measures such as restraining nets and ditches. Most of the existing rockfall simulators are based on particle models that consider the falling rock as an infinitesimal particle with a mass, called the lumped mass or stereomechanical models [1, 2, 3, 4]. Other models involve hybrid methods relying on simplified assumptions. The most common hybrid methods are based on contact searching for the movement of a dimensionless object and incorporate some aspects of rigid body impact for bouncing [5, 6, 7]. There are also some rigid body models in the literature that employ simplified versions of rigid body models [8, 9]. This study applies a more sophisticated rigid body theory based on rigid body impact mechanics (RBIM), which was developed by Stronge [10, 11, 12]. The new theory captures all modes of rigid body movement. Due to the importance of the rock geometry, single impacts of ellipsoidal and prismatic rocks with rectangular cross sections are investigated. The effect of rock slenderness on rebound velocities and energies is also investigated for ellipsoidal rocks. The correspondence between the model parameters and the data from the rockfall literature data will be discussed.

Jan 1, 2007

By E. Shelobolina, S. M. Pickering, J. E. Kogel

A long history of weathering and bacterial alteration processes have transformed Georgia’s Coastal Plain kaolins from dark organic muds to recrystallized white pigment-grade industrial clays. A sequence of six stages in development of these valuable mineral deposits is outlined over their Late Cretaceous and Tertiary deposition and alteration history. Anaerobic and aerobic iron oxidizing and iron-reducing bacteria are present in the Georgia kaolins. These bacteria may have had a major role in iron and organic matter removal during several of the alteration stages that occurred over the past 60+ million years. Iron was likely solubilized by both iron-reducing and iron-oxidizing bacteria, depending on availability of Fe(II), Fe(III), and NO3. Thus, over long periods bacterial activity slowly led to nearly complete groundwater removal of iron from the kaolin deposits. Further bacterial iron removal on an industrial process scale may eventually prove feasible. “Without the multitude of living reactions as channels for energy and electrons and without the enormous capability of life to transfer with and against chemical gradients, there would be practically no or at least a very reduced geochemical rock cycle on this planet.” (Krumbein and Dyer, 1985, p. 157)

Jan 1, 2002

By U. Thorley

Management of mine and tailings reclamation activities by surface mining oil sands operations in Alberta, Canada is experiencing increased national and international attention. Of particular concern is the ability of existing mines to execute and fund reclamation activities. Concern stems from a lack of demonstrated tailings reclamation technologies, perceptions of a poor track-record of reclamation activity by industry, and a lack of transparency with respect to the potential cost of reclamation activities relative to the monies secured in Alberta?s Environmental Protection Security Fund (EPSF). Limited information is publicly available regarding reclamation costs and technologies. Available data typically comes from disparate sources. This paper examines the expected costs of oil sands reclamation activities through a study of corporate Asset Retirement Obligation (ARO) liabilities, the Province of Alberta?sEPSF, and published data relating to reclamation costs.Issues relating to current liability funding are introduced.

Jan 1, 2011

By A. E. Koski

Two of the largest industries in northern Michigan, pulp and paper manufacturing and iron mining, formed a mutually beneficial partnership and collaborative research program to utilize paper mill residuals for waste rock stockpile reclamation. Historically, the majority of the paper industry’s residuals have been disposed of in landfills. The beneficial use of paper mill residuals for mine reclamation provides an environmentally sound recycling solution for the solids generated at northern Michigan paper mills and eliminates the need to strip additional overburden (glacial till) for final mine reclamation. Residuals offer a cost-effective source of organics and nutrients necessary for successful reclamation and waste rock stockpiles offer an economical and environmentally sound solution for disposal of residuals. The goal is to successfully pioneer technical development of paper mill residuals to accomplish vegetation of steep waste rock stockpile slopes and benches to establish a self-sustaining plant community that meets final reclamation requirements. Of the various types of iron mining wastes, rock stockpiles pose the greatest reclamation challenge. Success depends on incorporating sufficient organic matter into the rock stockpiles to produce a growth medium that can sustain vegetation without the need of overburden. This is an ongoing research program that is evolutionary in nature with numerous field trials, greenhouse studies, data collection and monitoring over multiple growing seasons. The program is a combination of innovative ideas and accepted reclamation practices that is proving to be a beneficial and economic approach to paper mill residual management and mine reclamation that will eventually lead from research to standardized reclamation procedures.

Jan 1, 2006

By H. Lyn Bourne

This is the fourth annual tabulation that gives mineral royalty information. The table presents previous information plus about two dozen new entries. In addition to the royalty information, some entries show the cost of purchased reserves. Last year's tabulation appeared in two issues, to accommodate all of the information. This year the format has been changed slightly so the table can be printed in one issue. This year's table presents the commodities in the same sequence as last year. Sand and gravel information appears first, followed by: crushed stone for aggregate; other stone; industrial sand; other industrial minerals; energy minerals (coal, oil shale, uranium); and finally metals. As always, a caveat relates to factors that influence the reserve values. The data should serve only as a general reference. The table is not intended to present an absolute scale of reserve costs. Several factors influence the value of mineral commodities. These factors include: • location and transportation costs (especially significant for most industrial minerals); • market conditions for both the commodity and the company acquiring the right to mine it; • quality or grade of the deposit as it reflects the amount of processing and beneficiation necessary to produce the finished product; • and legislative restrictions and conditions for mining a given material at a given site. These and other factors will influence reserve costs of reserves. The table shows the range of royalties and the variations in the basis of computing the fees. In a few instances, it gives the cost of acquired reserves based on purchase price and quantitative estimates of the material in place. The table lists the commodity; the location (either by state, US geographic area, or Canadian province); the cost (R for royalty and P for purchased cost); and the year in which the lease or purchase agreement occurred. The last column offers either comments or gives a footnote number for more information. The cost column requires more explanation. The units may refer to cubic yards (/yd), cubic feet (/cuft), tons (/T) (2000 lbs) or acres (/A). 1 cu yd = 0.76m3 1 cu ft =0.28m3 1st = 0.9 t7 1 acre = 0.40 ha or m2 In several cases the royalty is a percentage of the finished products, sale price and is levied against either the amount produced or the amount sold. We thank those who contributed information for the table: J. Dunn, T. Eyde, K. Loda, L. Morgan, F. Nix, H. Sorenson, and L. Williams. Several people have said they would like this to be an annual tabulation. That can happen if new information comes to the writer. What appears in the table is only a very small fraction of the cost information relative to the various commodities and the geographic areas for which there is royalty information. If you find this column of interest and possess information write or call: H. L. Bourne, c/o Neyer, Tiseo & Hindo, Ltd., 38955 Hills Tech Dr., Farmington Hills, MI 48018, (313) 553-6300. Only with new information can this become an annual and current source of reserves costs.

Jan 8, 1986

By G. E. Agar

In the April issue of Mining Engineering there is a technical note "New size laboratory ball mill for Bond Work Index determination" written by M. Nematollahi which is very confusing. My recollection is that a description of an experimental procedure should be such that someone skilled in the art should be able to reproduce the results. Applying this test to this particular article would according to me cause a failure to be registered. There are apparently three batch laboratory test procedures referred to in the article. One of these is the traditional Bond test with all its limitations such as dry grinding followed by exclusively dry screening, two attributes which fail to simulate conventional industrial grinding. There is a second procedure (NSBM) which the author is advocating as an improvement of the Bond procedure but from the description I doubt that anyone would be able to repeat the procedure. For instance, is the grinding to be done wet or dry, if wet at what pulp density, and how is the screening to be done, wet or dry or a combination?

Jan 1, 1995

By R. J. Latino

Because of the lack of a universally accepted definition or standard for RCA, we are left to our own conventions in the marketplace as to what is most ?effective? or a ?Best Practice? for our own facilities or organization. This lack of uniformity in the application of RCA produces an equal lack of uniformity in the measureable outcomes of RCA on the bottom-line from site to site and industry to industry. What is the definition of success for an RCA? Is it regulatory compliance? Is it some quantifiable measure of bottom-line performance? Is compliance and bottom-line performance the same thing? Can we measure the ROI we receive by doing compliant RCA? These questions must be adequately addressed if any definition of RCA is to be effective on the bottom-line. Like our various Corporate Vision and Mission Statements, what would be our Vision and Mission for RCA? When pondering the answer to this question, we should consider: ? What Key Performance Indicators will the Success of RCA be Linked to? This provides a direct correlation to the corporate dashboard and therefore garners support for the RCA effort when implemented at the sharp end. Not until we know what KPI?s will effectively measure our maintenance and reliability objectives can we begin to establish which opportunities will afford the greatest returns1. ? What Bottom-Line Metrics will be Tracked to Measure the Effectiveness of Our RCA Effort? Will it be increased production, profitability, regulatory compliance, etc.? Will it be decreased injuries/fatalities, claims, customer complaints, risks, etc.? We should be specific about these metrics and their correlation to the metrics on our corporate dashboard. ? What Will Trigger an RCA Investigation? Normally companies will establish quantifiable thresholds to be surpassed before an RCA will be conducted. Examples may be an OSHA recordable injury, a failure event in which production losses exceed $250,000, an equipment failure in excess of $50,000 or a regulatory violation. This is the norm. However, we should realize this is using our RCA skills totally on a reactive basis. High Reliability Organizations (HRO) strive for proaction and they also use RCA proactively. Why can?t we use RCA to analyze why unacceptable risks from an FMEA are so high? It is perfectly applicable yet rarely implemented in this fashion.

Feb 27, 2013

By C. H. Bucknam

Principles of Green Chemistry provide useful guidance for sustainable mineral process development. Laboratory bench scale testing was carried out using pregnant cyanide leach solutions, and a number of commercially available mercury precipitation reagents were compared using jar testing to determine the most efficient and selective reagents for mercury precipitation. The most efficient reagent identified was sodium polymeric thiocarbonate (NaPTC).Coagulation experiments with fine diatomaceous earth resulted in a stable precipitate, with good settling properties. On line monitoring of the mercury in solution is recommended for process implementation to conserve reagent removing approximately 90-95% of the mercury with minimal silver and negligible gold losses.

Jan 1, 2004

By Tim O’Neil

The US Bureau of Mines and the Santa Cruz Joint Venture (SCJV) are working on a production-scale, in situ copper recovery project in Arizona. The research is being conducted at the Santa Cruz site, located 11.2 km (7 miles) west of Casa Grande, AZ (Fig. 1). Santa Cruz is a 1.36-Gt (1.5 billion st) porphyry deposit averaging 0.6% Cu, of which 65% is oxidized, concealed beneath post-mineral alluvium at depths of 365-914 m (1500-3000 ft). The Bureau and the SCJV will evaluate in situ mining as a method for extracting copper from this previously unmined deposit. Research objectives of the Santa Cruz project are: - to demonstrate that an in situ research test can be operated in an environmentally acceptable manner ; and * to operate an in situ well pattern long enough to develop information on copper recovery and economic feasibility data. In situ mining of copper from undisturbed deposits has not been attempted commercially. There are several potential advantages with in situ mining: less exposure of miners to hazards, lower pital costs for the mine and plant and lower operating costs. In addition, there are no pits, dumps or tailings, which means less environmental impact.

Jan 1, 1991

By J. Wiese

Recently the operating philosophy at concentrators processing platinum bearing ores has started to move from a recovery dominated system to one in which the production of high grade concentrates at the expense of some recovery would provide greater benefits in the further upgrading of the platinum group minerals (PGM). The low grades usually obtained are associated with the presence of naturally floatable talcaceous gangue minerals in all PGM ores. Polysaccharide depressants such as guar gum and carboxymethyl cellulose (CMC) are used to improve the grades of the concentrates. Recent testwork has shown that the use of high depressant concentrations can prevent any naturally floatable gangue from reporting to the concentrate. The only gangue present in the concentrates would be due to its entrainment in the froth. Under these conditions much higher grades can be achieved. The sulphide minerals themselves, however, become susceptible to depression at high depressant concentrations. This work examines how the recovery of sulphide minerals in two Merensky ores was affected by the type and concentration of the collector in the presence of high depressant concentration (500 g/t) and that the response of the sulphide minerals was also dependent on the type of depressant used (guar or CMC).

Jan 1, 2009

By S. Chander, S. W. Musselman

The molecular structure of hydrophobic and hydrophilic groups in nonionic surfactants has been related to the wetting and dispersion of selected pigments. The nonionic surfactants included in this study are acetylenic diol based surfactants and ethoxylated alkyl phenols. The Langmuir model could be used to fit adsorption data. Further analysis of the data showed that the free energy of adsorption was a function of adsorption density of the surfactants at the interface. The change in free energy with adsorption density could be interpreted by considering a change in the orientation of the adsorbed molecules. Acetylenic diol based surfatants were found to have an area per molecule of 2-3 times that of similarly ethoxylated alkyl phenols. The wetting and dispersion properties of lamp black, a model hydrophobic surface, by these surfactants were investigated by contact angle measurements and particle size analysis. Acetylenic diol based surfactants with ethylene oxide contents between3.5 and 10 moles per molecule and alkyl phenol based surfactants with approximately 9 moles of ethylene oxide per molecule were found to provide superior wetting abilities. Longer ethylene oxide chains were required for superior dispersion capabilities within each family of surfactants. Complete wetting and dispersion was found to occur above the critical micelle concentration of the surfactants.

Jan 1, 2000

By G. Kordosky, A. Feather, M. Virnig, P. Crane

Introduction The post World War II nuclear arms race and interest in nuclear power generation resulted in a significant demand for uranium in the 1950’s. This led to the development of uranium solvent extraction technology and uranium became the first metal to be recovered on a large scale by solvent extraction (SX) (1), interestingly more than 100 years after the extraction of uranium from an acid nitrate solution using diethyl ether was first reported by Peligot.(2) For a variety of reasons discussed elsewhere (3,4) there have been upheavals in the supply demand picture and price for uranium since the 1960’s. (Figure 1) The low price of uranium from the mid 1980’s until 2004 resulted in a depression of new resource exploration and mine development along with uranium mine / mill closures and decommissioning. People with skills in uranium processing could not find suitable employment and many experienced engineers and metallurgists took jobs elsewhere or retired. This resulted in a significant brain drain with respect to uranium processing technology.

Jan 1, 2007

A glance at the accompanying table reveals that for the first time in many years the industrial minerals field did not post significant gains in production. Gypsum, cement, sand and gravel, and crushed stone production-which are very sensitive to construction industry performance-barely managed to stay even, or in fact, declined slightly. Even barite production, in spite of increased oil and gas drilling, was off 5% in 1979 from 1978. Domestic fluorspar production continued to decline while imports, primarily from Mexico, South Africa, and Spain, rose 11%. Worldwide production of iodine (which is used primarily as a catalyst, animal feed additive, and in ink and colorants, stabilizers, pharmaceuticals, photographic film, and disinfectants) grew about 9% on a worldwide basis-from 10.75 Tg to 11.16 Tg. This does not include US production. The two US producers increased demand as apparent domestic production increased about 5%. Increasing energy costs and the transportation situation have had a prohibitive effect on the industrial minerals field. The critical shortage of railroad cars, according to consultant Neil Johnson, is due to several factors: • High capital investment rind interest rates needed to build new equipment, • Accidents, obsolescence, and failure to repair equipment reduced car availability, •Reduction in some train schedules due to fuel economy, and •Increased turnaround time as a result of new safety regulations. Railroad rates have increased an average of 7% per year for the past 10 years. Last year's increases were about 11.1% due to fuel costs and surcharges. Truck shipments have increased their penetration in certain areas of the southeast because of the shortage of box cars and the producers' demand for quick shipment. Some producers report a 15-20% increase in truck use. In the feldspar-mica area, which formerly made most shipments by rail, trucks are now used for about half the shipments. Marketing prices, as expected, increased due to higher costs for energy, power, labor, and supplies used in production. Estimated average price increases were about 10% which, in many cases, did not cover increased production costs. These factors-rising energy costs and the critical transportation situation-resulted in an unsatisfactory year for industrial minerals. Stanley J. Lefond Cnntrihuting Editor

Jan 5, 1980

By G. E. d’Aquin

Sources of sulfur have varied based on technology and societal needs. It has been mined in its elemental form for centuries. Twentieth century technology brought thermal mining (Frasch, 1894) to the forefront of sulfur extraction. Then, by the 1980s, petroleum processing generated almost 40 percent of the 50 Mt (55million st) of sulfur in all forms (SAF) produced in the world. Metals processing (the reclamation of effluent gas by various means as “sulfur in other forms,” or SOF) followed at 30 percent of all sulfur values produced and then Frasch at 22 percent. Petroleum and gas processing now generate most of the elemental sulfur produced in the world. Single Two Frasch mines remain, one each in Iraq and Poland. Conventional mining of small to insignificant volumes also survives in Russia, Latin America and Indonesia. The volume of “recovered” sulfur (the name commonly given by the industry to hydrocarbon-derived material) generated will increase faster than energy consumption as oil and gas with greater amounts of sulfur are used and environmental restrictions on the sulfur content of the fuel consumed become more stringent.

Jan 1, 2005

By S. Boone, J. N. Shirlaw

INTRODUCTION Soft, near normally consolidated clays generally provide ideal conditions for tunneling using Earth Pressure Balance (EPB) shields. It is easy to turn the clay into a low permeability, viscous spoil that can be pressurized to maintain the required face pres-sure. Despite this, there are records of relatively large, and often quite variable, surface settlements over EPB driven tunnels in soft clay. To understand this variation it is necessary to identify the various factors that contribute to settlement. Tunnels in soft clay are ideal for study these effects in the field, as an unsupported void will close almost immediately, due to the low shear strength of the soil. In the short term, deformation in a soft clay will occur at constant volume, so short term surface settlements can be related to movements at tunnel level. In this paper, data will be used from EPB driven tunnels in Singapore marine clay. In all of the cases discussed the lining consisted of precast concreted segmental rings erected in the tail of the shield. The marine clay in Singapore has been studied, among others, by Tanaka et al.(2001). The clay typically has a plasticity index of 40 to 60, and the undrained shear strength (SU ) can be derived from: SU = 0.22 svo' where svo' is the current vertical effective stress. Figure 1 shows a summary of undrained strength/depth plots used for design on two sections of Singapore’s North East Line. The stability of a tunnel in clay can be assessed by comparing the stability number (N) of the tunnel with the stability number at total collapse (NTC). The stability number can be calculated from the equation: N = (?Z + q – Pt)/SU where: ? = the average unit weight of the ground above the springline of the tunnel Z = the depth to the springline of the tunnel from the ground surface q = the surcharge Pt = the support pressure within the tunnel The stability number at total collapse depends on the size, geometry and depth of the tunnel, and typically ranges between 5 and 9. Charts for assessing the number at total collapse are provided in Kimura and Mair (1981), based on the testing of model tunnels in a geotechnical centrifuge. For tunnels in the Singapore marine clay, the stability number of an unsupported tunnel would be over nine if the tunnel ois more than 8m deep. As a result, a support pressure

Jan 1, 2007

By Kal V. S. Sastry

Comminution is an important unit operation of mineral processing in terms of large tonnage of materials processed, huge energy consumption, and high capital and operating costs. Substantial research efforts have been directed towards the development of process-engineering tools including mathematical models, process scale-up procedures and computer simulation packages (Austin et al., 1984; Rajamani and Herbst, 1990; Kawatra, 1992). The simulation systems are found to provide significant cost savings by enabling efficient circuit design and development of control systems. Most of these simulators are built from scratch, do not make use of software modules from other sources and are designed with minimal usage of formal software methodologies.

Jan 1, 1995