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By William X. Chavez

The Mantos Blancos copper-silver district, a major copper-producing area since 1961, is located on the Tropic of Capricorn about 45 kilometers northeast of the northern Chile port city of Antofagasta, as shown in Figure 1. Copper oxide minerals occurring as atacamite (Cu C1(OH)3) and chrysocolla (copper silicate-hydrate) were discovered in the district in the early 1900's (Knobler and Joseph, 1962). The mine is situated in the northern Atacama Desert, one of the most arid regions on earth, and presently receives less than 1 cm per year of precipitation. The extreme aridity of the Atacama Desert is thought to have prevailed since at least Middle Miocene time (Mortimer et al., 1978) when development of important supervene copper enrichment was slowed in many areas of northern Chile (e.g., Chuquicamata, Exotica). Despite the paucity of precipitation, landform development is mature, with large alluvial fans and alluvial-filled valleys covering much of the region. In addition, the aridity and presence of salts have led to the formation of a sub-surface cementing of alluvium and colluvium by halite-rich caliche ranging from a few centimeters to over 3 meters in thickness. These factors, resulting in poor outcrop exposure, make even reconnaissance mapping difficult.

Jan 1, 1983

A Simulation Study on Two-Stage Grinding with High-Pressure Roller Mills By the application of high-pressure roller mill (HPRM) in the field of mineral processing, computer simulation can be used to predict overall performance of a grinding circuit based on data obtained from HPRM comminution test in pilot scale or industrial scale. Using the model developed by Klymowsky and Liu for HPRM comminution and an extended Plitt's model for classification, steady-state of a closed circuit grinding can be calculated by means of a virtual locked-cycle-test conducted on computer. This paper presents the result of a simulation study on two-stage grinding with HPRM as the comminution device. The emphasis is put on the influences of circuit-configuration and way of recirculating classifier's coarse-product on the overall circuit performance. The results show that two-stage grinding with HPRM has its merit and flexibility in meeting demands of various grinding tasks in mineral processing.

Sep 13, 2010

By John C. Machisak

THE INJURY data and experience at quarries and related plants of the United States are presented in this publication under the following general sections: (A) General injury experience: Tables 1 through 3: Contain current data on the number of injuries, injury-frequency rates, location, accident agency, degree of injury, and related employment data. (B) Injury experience at different kinds of quarries: Tables 4 and 5: Contain current, data on number of injuries, injury-frequency rates, locution, accident agency, degree of injury, and related employment data. (C) Injury experience by States: Tables 6 through 19: Contain current data on the number of injuries, injury-frequency rates, accident agency, degree of injury, and related employment data.

Jan 1, 1958

By Wilhelm Knickmeyer, Johannes Henneke

PREFACE For about 1 year Bergbau-Forschung GmbH, central research institute of the German Coal Mining Industry, undertakes full size tests for waterjet assisted tunnel¬boring in German coal mines (Fig. 1). These tests are performed with a tunnelborer of 2.6 m diam in an upper [ ]

Jan 1, 1979

By Edwin A. Clarke

[For almost 2 decades the Bureau of Mines has been Interested in converting solid fuels to liquid fuels. Small-scale laboratory investigations were carried on for a number of years.4/ This work wad expanded substantially under authority of Public Law 290, approved by the 78th Congress on May 5, 1945. As part of the. broadened program, coal-hydrogenation demonstration plant was designed and erected at Louisiana, Mo., where: hydrogen-manufacturing and compression equipment, shoes, electric power, and other utilities and facilities were available from a discontinued wartime ammonia works . The plant uses the direct -hydrogenation or Bergius process, but the process differs from prewar European practices in many respects. Many noteworthy improvements h eve bean made, particularly by substituting automatic instruments for manual control of process variable's, in line with modern American processing practices. The over-all objective of the demonstration plant is to bridge the gap between laboratory end commercial-scale operation by furnishing cost and engineering data to develop a synthetic liquid-fuels industry when it proves technically and economically justified. Fitting into the over-all program, specific objectives o early runs were to (1) train personnel who had no experience with this type of operation, (2) break in the installed equipment, (3) obtain successfully integrated operation of the entire plant, and (4) work towards obtaining data on the hydrogenation of coal-tar oil and a typical low-ash coal. In beginning fan integrated operation, it is common practice to operate and obtain reaonably smooth performance of each unit before the over-all operation is undertaken. The first part of the plant completed was the refinery, consisting of several fractionating systems, a stabilizer, and a chemical treater.]

Jan 1, 1953

By A. K. Tripathy, P. K. Pattnayak, H. S. Ray

The effects of water addition on the solid-state reaction between Cr2O3 and Na2CO3 at low temperatures (up to 873 K) were investigated to determine its possible influence on the reaction rate and the degree of conversion to soluble chromate. Experiments at high temperatures were conducted for comparison. It was found that adding water to the mixture before roasting enhanced both reaction rate and yield significantly. The reactions followed the Lesokhin-Tempelman equation at low temperature and the Ginstling-Brounshtein equation at above 973 K; the respective activation energies were 95 and 22 kJ/mol

Jun 19, 1905

The paper presents a brief history of endeavours to start a mining education programme which began in the days when Papua New Guinea's first large mine, at Panguna (Bougainville), was coming into production. The status of the Public Investment Programme in Mining Engineering and the facilities being created for the education and training of Papua New Guinean citizens in mining and mineral processing are also described. Future expansion plans are also detailed including those for the commencement of petroleum engineering and geological engineering which would include courses in mining geology, exploration geology, engineering geology and petroleum geology. The paper also looks at the manpower training requirements in the lower levels of mining industry such as pit foreman, blasting foreman and other similar positions. It stresses the need to start mining technical training programs at pre- employment level and at certificate level in a technical college, possibly Lae Technical Colleqe.

Jan 1, 1991

A review is presented of developments in mill liners to improve performance in terms of wear, impact, as well as mill grind and throughput. These developments are in response to the growth in size of SAG mills and the use of larger ball loadings and ball sizes in modern SAG milling practice. Shell liner developments include specific mechanical design features such as special bolting, directed metal flow to prolong liner life and a focus on the process aspects of the mills to provide more effective grinding motion with reduced wasteful ball-on-liner impacts. Grate design developments aim to provide high throughput of material, especially in the larger size fractions, while providing good impact and wear life. Curved pulp lifters are designed to ensure, at high mill speeds, complete discharge of coarse solids from the mill.

Jan 1, 1999

By J. R. Welsh, D. J. Palmer, O. M. G. Newman

"The use of calcine for selective zinc precipitation requires specialist knowledge to achieve satisfactory flowsheet design. Calcine from the bed of a fluid roaster is preferred, and factors such as the size distribution of ground calcine, the stoichiometric ratio of the calcine precipitant to the initial dissolved zinc concentration and the moisture content of the resultant filter cake are parameters which require critical attention. Extensive testing in a fully-integrated electrolytic zinc plant pilot plant has demonstrated that properly designed selective zinc precipitation plants using calcine as the precipitant are reliable operating units.The advantages of using calcine instead of limestone for selective zinc precipitation include a decreased cost of reagents, as well as avoiding the formation of by-product gypsum.Process simulation modelling has demonstrated that the use of calcine in this context has widespread application in the design of zinc plants with superior impurity and water balance control characteristics. A particularly powerful approach involves closed circuit washing. In this mode, filtrate from the selective zinc precipitation step is used to wash a zinc plant residue such as jarosite, and the resulting filtrate is returned to the selective zinc precipitation section. IntroductionThe Selective Zinc Precipitation (SZP) Process, developed and patented by the Electrolytic Zinc Company of Australasia Limited (EZ) may be used to achieve simultaneously, water balance and impurity control in an electrolytic zinc plantO,2). Impurities which may be controlled by the SZP process include chlorine, magnesium, manganese, potassium and sodium.In the SZP process, basic zinc sulphate is precipitated from a zinc sulphate solution by either limestone, lime or a compound containing zinc oxide, usually calcined zinc sulphide concentrate (calcine) or alternatively zinc oxide fume .The solids containing basic zinc sulphate are separated, typically, by filtration and returned to the zinc plant circuit as a neutralizing agent. The zinc depleted solution can either be discarded, or used to wash residues, thereby achieving water balance and impurity control (Fig. I)."

Jan 1, 1988

By J. D. Jorgenson

?? U.S. domestic production peaked at 120 Mt during years of the Korean Conflict120 Conflict ?? Pellet production increased, as highPellet high-grade ores decreasedores decreased ?? Until 1982 recession, most U.S. iron ore mines owned by steel companiesmines companies ?? Large Canadian iron ore mines brought into production after 1950into 1950

May 1, 2011

By Corry Goumans, Dwayne Wallace

"On July 1, 1997, a rockslide occurred on the I-40 in Hayward County, North Carolina that completelyblocked all lanes and disrupted traffic flow in the region. Remedial measures were undertakenimmediately in order to open traffic, however on-going geotechnical investigation revealed stabilityconcerns that necessitated closing the highway to ensure public safety. Access to the top of the slope was available only from the bottom of the slide on the Interstate I-40. Excavation and trim blasting started from the top and along the west slope of the failure, however, additional geotechnical evaluation indicated that slope stability remedial measures were required to support the western rock slope mass."

Jan 1, 1999

By Robin Shepherdson

Security concerns have prompted the Department of Homeland Security to investigate the use of recording systems on all vessels holding materials used for blasting; a new regulation is expected in the near future. By measuring the strain developed in the legs of vessels with bolt-on sensors, it is possible to monitor the weight of vessel contents. Several companies make this type of sensor and recent versions give the required accuracy. This paper describes two generations of sensor, the second generation having a simpler method of installation that uses standard power and hand tools. Three types of indicator are available to monitor the material weight. 1) A simple electronic bar-graph indicator with a digital weight display. 2) A touch-screen display showing bar-graphs of multiple silos with digital weight displays plus their associated trend graphs, recent readings and an alarm log. 3) A data acquisition unit which acquires the weight digitally from up to 32 vessels and stores the raw and filtered date and time stamped data in a local computer database. This local computer then transmits the data via an Internet connection to a secure central database which allows the weights of all the storage vessels for a company to be viewed anytime and anywhere via the Internet. Historical trend graphs can be viewed and the data can be uploaded into an Excel file for further processing; for example to determine filling or discharge amounts. In addition, E-mail and SMS (Short Message Service) text alerts can be sent automatically when selected alarm levels are reached. Current research and development includes connection of vessels to the central database by a cellular wireless modem when a local computer or Internet connection is not available, as well as connection of remotely located vessels to a central point via “Wi-Fi bridge" radio data links. Future versions will include digital I/O (Inputs and Outputs) to record, for example, activation of filling and discharge devices as well as opening and closing of doors.

Jan 1, 2015

Stress induced, gravity-assisted failure processes typically dominate long before stress levels approach the strength of the intact rock (at approximately smax > 0.4UCS where smax = 3s1 ? s3 and UCS is the Unconfined Compressive Strength of the intact rock (Martin et al. 1999)). Under these conditions, discontinuities typically become clamped and the failure process becomes brittle. This brittle failure process is dominated by new stress induced fractures growing subparallel to the excavation boundary. While it is possible to identify areas with the potential for brittle failure, for example, using the general assumption that brittle failure will occur in areas at right angles to the major principal stress (Hoek et al., 1995), when the threshold smax > 0.4UCS is reached in areas around the tunnel boundary, or elastic modelling and the Hoek-Brown brittle parameters proposed by Martin et al., (1999) (i.e. m? 0 and s ? 0.11), amongst others, recent observations discussed by Everitt & Lajtai (2004), and Kaiser (2005; 2006) suggest that brittle failure processes are enhanced when structural features such as joints, weakness zones, bedding planes or foliations are preferentially orientated around the excavation boundary creating stress raisers which in turn facilitate the stress-driven rock mass disintegration process (e.g., as illustrated by Everitt & Lajtai (2004) on Figure 1b). Such weaknesses induce stress heterogeneities that thus promote tensile-spalling failure processes (Diederichs 2000). The observations suggest that stress induced damage can occur ?prematurely? depending on the orientation of micro and macro structures in situations where the known stress conditions should not yet initiate brittle failure processes. In general, when structural features (micro and/or macro), especially foliations, are present in a rock mass, the strength is effectively reduced, largely due to tensile strength heterogeneity in areas depending on the orientation of the structural features with respect to the excavation boundary. As a result, stress induced damage could occur in areas not normally considered due to the influence of anisotropy (Figure 1).

May 1, 2009

By Jack Zhang, Yunguo Tang, Baodong Zhao

"Rare earth elements (REEs) have numerous key applications in both traditional and advanced technologies. A shortage of some critical REEs is expected due to the discrepancy between the REE abundance in REE deposits and the REE demand from the market. For example, Neodymium, Europium, Terbium, Dysprosium, Erbium and Yttrium are expected to be in short supply. REE recovery and separation from secondary resources such as uranium wastes, heavy mineral sands, and recycled materials can balance the shortfall in a cost effective way.The Saskatchewan Research Council (SRC) is engaged in the development and commercialization of complete REE recovery and separation technologies in Canada. One of SRC’s newest developments is the design and commissioning of a heavy rare earth (HREE) separation pilot plant. The pilot plant uses hundreds of stages of solvent extraction (SX) to produce high purity individual HREEs from both primary and secondary resources.This paper presents the design of an HREE recovery process for the particular case of uranium processing wastes. The separation results of a group separation are reported and discussed, as well as the issues and the challenges of the development, commissioning and operation of the continuous SX pilot plant.IntroductionSignificant amounts of strategic specialty heavy rare earth elements (HREEs) are found in uranium wastes in Saskatchewan. It estimated that about 47 tonne/a of heavy rare earth element oxides (HREO) including 27 tonne/a of Y2O3, plus 6 tonne/a of Sc2O3 are in the raffinate of every uranium mill for potential recovery. Since the HREEs are already in the raffinate, cost effective HREE production is promising in Saskatchewan.Selective precipitation including nutraulization, oxalate and double-salts precipitation, as well as sulfide precipitation, ion exchange (IX) and SX are commonly used technologies for the recovery and purification of REE solution. REE oxalate precipitation is an effective technology to remove Fe, Al, Ca, Si and other impurities by taking the advantages of the solubility difference between oxalates of REEs and impurities in acidic solution (Xu, 2005)."

Jan 1, 2017

By D. Fray

Electrochemical processing using molten electrolytes is undergoing a considerable renaissance due to several innovative ideas being explored both in the laboratory and also at the pilot scale. Several of these new ideas are related to developments in energy generation and storage and involve solid electrolytes. Sodium has been prepared by the electrolysis of sodium carbonate or sodium hydroxide with the transfer of sodium ions through a sodium beta" alumina membrane and magnesium oxide dissociated by the removal of the oxygen through a stabilized zirconiaelectrolyte incorporating a fuel cell electrode. By using halides with highly electropositive cations, such as molten calcium chloride, it has been found that the favoured cathodic reaction, when oxygen is present, is the ionization of oxygen and not the deposition of calcium. This approach has been applied to the reduction of many metal oxides including titanium, zirconium, niobium and rare earth oxides and, by using a mixture of oxides as the cathode, homogeneous alloys are produced. This concept can also be applied to deoxidation of solid and liquid metals. Refining of metals is possible using intercalation compounds and, in a completely different application, it has-been found that, by intercalating alkali metals by electrolysis of alkali halides into graphite, it is possible to produce carbon nanotubes and nanoparticles. The technological opportunities of these various concepts will be discussed.

Jan 1, 2004

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By Kenneth M. Maas

The U.S. Bureau of Mines began a five-year study of the 7.0 million acre Ketchikan Mining District during 1990. This study is part of the Bureau's ongoing statewide mining district evaluation program. The study area was subdivided and then prioritized by mineral potential into work units. Bureau field work in 1990 focused on the southern portion of Prince of Wales Island and vicinity. Extensive mineral resources have been mined historically in the area and are presently being evaluated by private industry. Information in this report is based on an extensive literature search and Bureau field work. Over 150 mines, prospects, and mineral occurrences were visited in 1990; an aggregate of 1,300 rock, placer, and limestone samples were taken; and nearly 3 miles of underground workings were mapped. Many prospects, some untouched for more than 80 years, were mapped and sampled. High metal values at several prospects were confirmed by Bureau sampling. Reconnaissance sampling along logging roads on Southern Prince of Wales Island revealed mineralized areas not previously recorded. Follow-up work at many locations is planned for the 1991 season.

Jan 1, 2011

"Generation and removal of fines are considered in the context of the mill and classifier as a single-unit process in which grinding rates and mechanisms, mill residence time distribution, circulating load, and classifier performance all interact to effect the overall grinding circuit productivity. Required process design specifications are identified, and a computer assisted design procedure for application of hydrocyclones in closed circuit grinding is presented. INTRODUCTIONThe purpose of the grinding circuit is to carry out the size reduction necessary to suitably prepare material for the upgrading process(I) The desired product size specification being the d1st1nguishing criterion between the ""fines"" (smaller than desired product size) and the ""coarse"" fraction (larger than desired product size), the capability of the grinding circuit to perform its task effectively depends on the nature of two processes that are taking place;(a) size reduction of the coarse material, and,(b) removal of fines from the system."

Jan 1, 1984

By Sara Jane Boles

In recent years the interest in rare-earth compounds as refractory materials has exceeded the available literature on the subject. While some basic properties, such as density and melting point, of the more readily available rare-earth compounds have been reported in the literature, relatively few papers can be found that deal comprehensively and primarily with high-temperature refractory properties and applications of rare-earth oxides, carbides, sulfides, and nitrides. Therefore, this bibliography has been pre-pared for the use of the ceramic industry as a guide for locating and utilizing the scattered and frequently fragmentary information available. The term "rare earths", as applied in the literature search for this bibliography, is understood to include the following elements: cerium, dysprosium, erbium, europium, gadolinium, holmium, lanthanum, lutetium, neodymium, praseodymium, samarium, terbium, thorium, thulium, uranium, and ytterbium. (On the periodic chart, these elements appear as numbers 57 through 60, 62 through 71, 90, and 92.) It is emphasized that many of the abstracts included are from papers in which the rare-earth compound or compounds are treated along with several other ceramic materials, are mentioned only secondarily, with primary interest placed on a more commonly used refractory material, or are used as part of a mixture of materials formed experimentally and reported on in the paper. As the better known rare-earth materials, such as the oxides of uranium, thorium, and cerium, appear more frequently in the literature, they also appear more frequently in this collection. Articles abstracted include only information on the basic properties that are of interest to the refractories investigator. References to crystal lattices and related topics are generally excluded from this publication. The temperature 1,500° C. has been set arbitrarily as the lower limit for reported data on thermal properties. However, because of the scarcity of information, some reports are included in which data are limited to those obtained at lower temperatures. Many of the articles abstracted include lists of references that will be of additional assistance in pursuing specific lines of investigation.

Jan 1, 1962

By Karl J. C. Harries

"8.1. INTRODUCTIONThe purpose of this chapter is not to provide precedents or examples of provisions, but rather to offer some comments that may be worth considering in the negotiation or review of an agreement. These comments are not intended to be exhaustive. It must also be noted that, although the chapter is written in the context of a common law joint venture, the concepts and concerns for the most part apply equally to a corporation that is owned by only a few shareholders for the purpose of participating in the project held by the corporation.The corporation has the advantage of having much of its organization established by local corporate law, but the particular wishes of the shareholders will appear in a shareholders’ agreement. The principal differences will be surprisingly small, save for the acquisition provisions that appear in a farm-in agreement1 and the substantial portion of the joint venture agreement devoted to creating and organizing the joint venture entity. Where the joint venture agreement refers to venturers and committees, the shareholders’ agreement will refer to shareholders and the board of directors, but both will have to deal with such basic matters as decision-making, default, dispute resolution, first refusals, funding, and carrying out work on the project. For convenience, this chapter usually refers to “venturers”, which may be taken to include shareholders.Negotiations give rise to many varying circumstances and concerns, and the main asset of the negotiator is an open and flexible mind. A desired result can often be accomplished indirectly in circumstances where the other side has adopted an inflexible position on a suggested approach. As precedents and standard forms tend to focus a negotiator’s thinking, they can be counterproductive. It is after the deal has been agreed to that a precedent can be of great assistance to the draftsman.The concepts are arranged in alphabetical order for convenience, not to suggest their sequence or position in an agreement or their relative importance. An agreement should adopt a progression of subjects in what the parties consider a logical sequence to read and work with. However, experience has indicated that it is best to set out in a single article the substance of the deal (i.e. the terms relating to the farm-in and what the acquiring party has to do to acquire his interest), preferably near the beginning of an agreement. The acquisition of the interest is, after all, the first order of business. The joint venture provisions will then follow in a reasonable sequence. It is also worthwhile to devote a single article to any special provisions that may apply during the earn-in period. For example, it may be provided that, although all work is to be done by the acquiring party as operator (with the duty of care, liability, and reporting requirements as set out in the joint venture sections of the agreement), but during the acquisition period, the acquiring party, acting as operator, may be at liberty to do such work as he wishes, without the need for any committee or other approvals, and committee meetings may be suspended.2An agreement is divided into paragraphs and articles to make it easier for the parties to read and understand, and to assist a party in finding “that provision” when the need arises. A comprehensive table of contents will also assist the parties who must work under an agreement. An added benefit of a table of contents is that in preparing it, the draftsman sees the overall structure of the agreement and will often catch and correct flaws."

Jan 1, 2003