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By W. Burger

For the development of deep, hard rock, mines fast access to the orebody is critical. In some cases the mineralized area is more than 1,500 m (5,000 ft) below surface. Excavation of shafts or declines is typically on the critical path of the project schedule. Saving time on those activities can significantly increase the net present value of the mining project. Mechanical excavation methods are a step-change in excavation performance and labor safety compared to drill-and-blast operations. In hard rock conditions, roadheaders cannot be used effectively, so disc cutting is the first choice. For excavation of declines, tunnel boring machines (TBM) can be used in many cases. These provide, in certain rock conditions, considerably higher production rates com-pared to drill-and-blast excavation. Herrenknecht AG has developed a vertical shaft sinking machine (VSM) that is able to excavate shallow shafts in soil and medium soft rock. The ground is excavated by a roadheader boom. The muck is removed by a slurry system or a pneumatic system in combination with hoisting of skips. These machines have been applied successfully on shafts down to 100 m (300 ft). A pre-sink for a deep mine shaft has been excavated by this technology. For deep, hard rock shafts, a new shaft boring system has been developed by Herrenknecht AG in collaboration with Rio Tinto. Based on proven technologies, the system uses a unique arrangement of existing proven technologies. The system integrates excavation, mucking, primary rock support, installation of the final lining and shaft infrastructure. This new system improves the health and safety of shaft construction. Detailed performance estimates indicate significantly higher shaft construction rates are possible compared to conventional shaft sinking methods.

Jun 1, 2010

"INTRODUCTION The characterization of groundwater hydrogeology is a common component in feasibility studies, geotechnical investigations and regulatory permitting for mining operations. The lithology at a location of interest may include several discrete water-bearing units; and the means of isolating each for testing can be accomplished through the use of inflatable packers. Consideration for testing during drilling program planning and communication between all stakeholders is essential to ensure that the Mine, Drilling Contractor and Hydrogeological Testing Specialist (Specialist) are ready to perform packer testing when the call is made to mobilize. Often, the notice to mobilize can be delayed and then occur with little warning due to the issues that can occur during drilling of very deep boreholes, as well as other factors. Hydrogeological investigation reports and journal articles generally discuss testing methods and results, with limited information available describing the planning and coordination of the field testing program, as evidenced by the lack of references cited below. The source of inspiration for the subject matter of this paper is grounded in the author’s past shortsightedness; with the hope that others not share similar misfortunes but experience success through thorough preparation for their future hydrogeological testing programs. The sections below focus on the planning stages of a field investigation using inflatable packers, including considerations for site specific conditions, designation of stakeholder responsibilities, and communication of testing expectations. Following these sections is a presentation of two examples of successful field programs and lessons learned in addressing problems encountered along the way. PRELIMINARY PROGRAM PLANNING & CONSIDERATIONS From the onset of planning for drilling programs, the Specialist should be in communication with the Mine to review plans and identify fatal flaws which could impede collection of hydrogeological data. Preliminary scope decisions can significantly affect the budget and duration of hydrogeological field programs and may dictate the means by which the field data is collected. The issues that need to be considered include the following factors. Testing Objectives The setup of the packer tool is dependent on the testing objectives. Is the goal to estimate bulk aquifer hydraulic conductivity or to identify discrete discontinuity hydraulic characteristics? Are groundwater samples needed? The answers to these questions affect selection of test interval length and what instrumentation might need to piggyback on the packer tool. Identifying the testing goals initially will provide adequate time to prepare packer equipment for mobilization. Borehole Size While inflatable packers come in many shapes and sizes, some sizes are more readily available and easier to procure on short notice. Packers for NQ and HQ size boreholes have been historically easy to procure and are commonly used in exploration drilling. Packer equipment is available for smaller holes, but it becomes more difficult to fit instrumentation down-hole as the borehole size decreases. This is particularly a consideration if collection of groundwater samples is required. In addition, risks of losing the hole or equipment downhole are greater for smaller boreholes. Larger boreholes require larger packers and clearly require more effort and heavier capacity machinery to manually manipulate due to the increased size."

Jan 1, 2017

By Robert S. Lehto

Zinc concentrates received in La Oroya zinc refinery are marmatitic in nature, contain about 11% iron and traces of other metal values, Figure 1 shows the zinc circuit. The calcine from the roasted concentrates is leached in spent zinc electrolyte. Major part of the impurities is iron which has been oxidized to its trivalent form, This is the origin of the zinc leach residue for which the ZILERET process was developed and so named. The impure liquor from the leach is sent for purification and thence to electrolysis- zinc deposits on aluminum cathodes from which: it is stripped, melted and cast into slabs Typical assays of zinc calcine and leach residue are given in Table 1. Metal values contained in the leach residue, without counting any value of iron, amount to roughly $130 per short ton.

Jan 1, 1969

By Albin E. Anderson

The PSM System has been available to the mining industry for nine years. During this time, many of the more than 160 Systems sold have been put to practical use and have provided the owners a handsome return on investment. In this paper, the author will briefly discuss how the System works and how it can be put to use in automatic grinding circuit control. Throughout, detailed consideration will be given to the many factors that can significantly influence how successful a specific application is.

Jan 1, 1979

By Bo Arvidson

SALA MAGNETICS, INC. is now operating a 15 tph continuous high gradient magnetic separator, the SALA-HGMS® Mark III Carousel, as part of a complete mineral processing pilot plant installed at Sala's Cambridge headquarters. The Mark III can generate a maximum magnetic field of 18 kG making it possible to process even weakly magnetic, finely ground ores and ore tailings on a continuous basis at the performance level achieved in Sala's cyclic high gradient magnetic separators. Test results on iron ores, clay, and decoppering of molybdenum concentrate will be discussed. Bench scale tests have been performed on all of these materials using the SALA-HGMS® Model 10-15-20 Cyclic Magnetic Separator. A direct correlation may be made between cyclic and carousel results. Sala's Mark III Carousel high gradient magnetic separator is designed to permit scale-up to machines capable of processing two hundred (200) tons of ore per hour and more.

Jan 1, 1976

By W. W. Wen

The objective of this investigation was to study the electrokinetic behavior of oxidized coals to indicate the feasibility of separating oxidized coals from ash materials and pyrite by an mine flotation process. The effects of soluble inorganic electrolyte products from coal oxidation were also examined. The electrokinetic behavior of coals of different rank and degree of oxidation were studied by an electrophoreses technique. Generally, increasing the oxidation increases the negative value of the zeta-potential and decreases the isoelectric point (IEP). Flotation results indicate that the flotation recovery increases with decreasing pH values, and that with ferrous sulfate at pH 6.5 the flotation recovery is optimum while the pyrite was depressed. Comparing the flotation results with the electrokinetic results verified that in the presence of ferrous sulfate, the maximum hydrophobicity of oxidized coal with dodecylamine and frother is near its IEP which is around pH 6.5 to 7.0.

Jan 1, 1976

By J. C. Mullen

Today, the coal mining industry is more knowledgeable on the potential negative economic consequences associated with improper management of hazardous substances and various types of solid waste. The practices evaluated during environ-mental audits are discussed and example situations are shared from previous audits of coal mines and analogous situations. The importance of assessing and understanding purchasing, warehousing, safety, maintenance, electrical, operations, and environmental management practices and procedures is highlighted as a key to a successful and practical program. A waste minimization approach is presented including strategies for screening product purchases, product substitutions, and testing and record keeping.

Jan 1, 1992

By C. Ek

Tailings originating from the gravity concentration of a gold ore containing about 14 g/t Au have been treated by various beneficiation methods. These tailings have been screened on the 147 and 74 micron sieves and the two coarsest fractions have been separated on shaking tables with unsatisfactory results, but the concentrates have been examined in polished sections for mineragraphic analysis. Very simple flotation flowsheets have been applied to collect most of the gold, recovery and grade varying with the regrinding time in a ball mill. Cyanidation tests have shown that this type of treatment is also applicable to such tailings.

Jan 1, 1991

By Karl C. Dean

To assist in the reduction of environmental degradation resulting from milling operations, the Bureau of Mines has developed, and successfully demonstrated, chemical, vegetative, and combined chemical-vegetative procedures for stabilizing milling wastes under varying environmental conditions. Costs of achieving reclamation using these stabilization procedures are compared with those of other physical and vegetative approaches. The Bureau's chemical-vegetative procedure for establishing vegetation directly on fine-sized wastes compares favorably with other stabilization processes that have been used.

Jan 1, 1972

By M. L. Klohn

The Felder ore deposit is a 5,000,000-pound uranium deposit in the South Texas Coastal Plain. It occurs in the basal sand of an Oakville Formation (Miocene) alluvial system. The host sand is a carbonate-rich arkose which contains virtually no carbonaceous debris and has been reduced by the local introduction of hydrogen sulfide. The ore lies well within the reduced zone and occurs as coffinite and uraninite that fill interstices and coat and replace grains. The overall geometric configuration of the ore is that of a winged, crescentic ore roll. Weak mineralization extends the wings of the ore roll and gives greater expression to the roll character. Departures from the shape are controlled by discontinuities in bed- ding and by proximity of the ore to the surface. Associated with the uranium is a broad halo of anomalous molybdenum. Subsidiary mineralized trends suggest a pre-existing up-dip position for the main roll. Oxidation from the surface largely destroyed this previous roll by solubilization of uranium. Uranium subsequently migrated into favorably reduced sand and reprecipitated at the present roll position.

Jan 1, 1970

By R. C. Schmidt

The Mont Klahoyo magnetite deposit is located about 600 km northwest of Abidjan, Ivory Coast. During an exploration period ending in 1977 an international joint venture group investigated the deposit and proved reserves of 670 million tons grading 36% iron. The deposit, occurring at the northeast end of the Baoubly-Kiriao chain of Precambrian iron formations, is associated with amphibolites, pyroxenites and gneisses of the Liberian Shield. At Mont Klahoyo occur two separate iron formations of which the lower member is the ore body. This lower member consists of a highly metamorphosed - banded quartz-magnetite iron formation in which iron silicate bands alternate with beds of quartz-magnetite. mphibolite-pyroxenites and sillimanite-cordierite-garnet gneisses form hanging and footwall rocks. The iron formation has been folded into an elongated overturned "Z" shaped major drag fold with axes trending and plunging approximately northeast. Beds are vertical or dip steeply to the southeast. The ore zone has an average thickness of 130 m and outcrops intermittently over a distance of approximately 5.5 km. Based upon detailed studies of drill cores and the results of ore dressing test work, eight stratigraphic units, identified as K-1 to K-8, are recognizable in the iron formation. Four interbedded units are low grade silicate zones (silicate facies) with the remaining quartz-magnetite units (oxide facies) repre¬senting the important ore zones of the Mont Klahoyo deposit. The ore-bearing "K" units are subdivided further, based upon their specific lithologies, iron content and concentration characteristics, into eleven ore types. The identification of these ore types is considered particularly important to mine planning and flowsheet design. A cap of oxidized materials overlies the primary quartz-magnetite iron formation but no enrichment has occurred. It is proposed that the Mont Kalhoyo iron formations were deposited, possibly chemically, in a volcanic environment as a siliceous iron formation with volcanism providing the primary source of iron and silica. Metamorphism converted the siliceous iron formation to a relatively coarse-grained quartz-magnetite-silicate iron formation.

Jan 1, 1979

This paper presents the results of an investigation of the stability of the mass flow rates and average pellet size in the different streams of an industrial-scale balling circuit. The variables in this study include water content, drum speed and fresh feed rate. It was found that both the mass flow rates and pellet diameter are greatly disturbed when a change, positive or negative, in any of the variables takes place. For most of these disturbances to be damped don, a period of one hour or so is required. When a disturbance in the feed rate was made, the transient period extended to more than one and half hours (the duration of the experiment). It was observed that there is an interaction between the drum speed and moisture needed for producing an acceptable green ball product. The moisture content of the product pellets was found to be a function of the pellet size, with the larger pellets retaining a higher moisture content.

Jan 1, 1980

By Reginald E. Reid

Mining on Bureau of Land Management (BLM) administered lands is affected by Federal laws and regulations requiring the mining industry to plan for the environmental consequences of surface disturbance. Regardless of the requirements for obtaining a claim, permit, lease or contract to mine, a notice or a mining and reclamation plan will be submitted and an acceptable environmental document must be prepared prior to mining. A bond may be required based on the results of the environmental evaluation, public interest and the operator's past history of compliance. In several areas, Federal requirements are different from California's requirements under their Surface Mine and Reclamation Act (SMARA). Therefore, the BLM is negotiating with the State in order to work out problem areas of responsibility and duplication of effort.

Jan 1, 1984

By George M. Leonard

Mineral commodities on National Forest System lands contribute to the nation's well being. Access to these commodities is dependent on public perceptions of the effects of mineral operations on other resources. An outlook is described which the Forest Service believes is essential to the minerals industry if it plans to continue seeking minerals on National Forest and Grasslands.

Jan 1, 1991

By A. K. Kuhn

In virtually all jurisdictions, comprehensive environmental protection regulations or standards are in place that apply to all industries, including mining. The only other legitimate mine-permitting concern is post-mining land use (PMLU). PMLU includes all uses of land after mining as well as the ecosystems appropriate for those uses. Although flawed, the New Mexico Mining Act (NMMA) of 1993 is a PMLU-based permitting statute. It requires measures during closure that will establish a PMLU or self-sustaining ecosystem for each mine unit. PMLU-based permitting avoids prescriptive, one-size-fits-all measures and keeps permitting focused on the legitimate goal of responsible land management..

Jan 1, 1999

By Sammie D. Guy

This paper discusses the subject of "Improving Contracting Methods" from the owners point of view, particularly the public. An overview is given of the work of the U.S. National Committee on Tunneling Technology and some apparent results of the implementation of these recommendations or lack thereof. Selected recommendations that are not being implemented are discussed as to the the desirability and the possible impact of their implementation. Impediments to acceptance of the recommendations are identified and solutions proposed. The difference in the flexibility, attitudes and approaches of owners, public, quasi-public and private, toward improving contracting methods are discussed. Particular emphasis is given to the fact that the onus to improve is on the owner because they usually develop the contractual language or at least have the final decision on its content and are or should be an equal party to the contract during its administration.

Jan 1, 1983

By Paul C. Schmall

In recent years, several geotechnical methods have been successfully applied to ash pond closure. These include modified dewatering techniques with wellpoints and wells to physically drain the material, soil mixing to create a soil-concrete material for improved accessways as well as improved ground structures within ponds to act as barriers or gravity dams, and geotechnical instrumentation to serve as an early warning of the potential for liquefaction. Given the parallels between fly ash and sluiced in place mine tailings, the application of fly ash remediation method to mine tailings shows significant potential, as illustrated in this paper.

Feb 1, 2024

By J. C. Stankus

In this paper, an innovative concept in longwall tailgate support is discussed. This new concept utilizes a new high capacity roof truss system in lieu of conventional wooden crib block. The first field test was conducted at Bailey Mine and was very successful. Similar tests have been installed in other mines and seams. An extensive instrumentation plan was designed and implemented in the truss test area. The test data has shown that the dynamic roof truss system effectively controls the various abutment pressures caused by longwall mining thus maintaining a stable tailgate entry.

Jan 1, 1995

By H. K. Conn

This paper discusses briefly the evaluation of chrysotile asbestos deposits in ultramafic rocks. Such deposits are limited to serpentinized peridotite and/or dunites. The purpose of any evaluation is to determine whether a deposit contains sufficient ore mineral to justify profitable exploitation. Dimensions of a mineral zone are established by conventional methods, such as mapping, ground magnetic surveys, diamond drilling or underground exploration. The value of the contained asbestos fibre Is dependent on numerous physical properties such as fibre length, strength, flexibility, as well as the actual amount of fibre present. The determination of grade is difficult. The Quebec Standard Test (Q.S.T.) is used to grade fibre according to the proportionate lengths of fibre present. A method of visual vein counting allows calculation of an approximate percent fibre together with a simulated Q.S.T. Various drilling methods are discussed, diamond drilling is favored. Bulk sampling is required to determine fibre quality. Correlation of visual techniques and laboratory methods are often difficult. Reasons for any variance are discussed. Underground bulk sampling of most potential ore zones is strongly recommended to confirm the viability of the property. Evaluation of slip fibre deposits requires greater reliance on laboratory testing as visual methods are difficult to apply. Cross fibre has greater inherent strength.

Jan 1, 1971

By K. S. E. Forssberg, J. A. Jirestig

Laboratory investigations on the possibility of using magnetic separation for the recovery of sulfide minerals have been reported. A survey of several sulfide ores and flotation concentrates indicated that, in most cases, magnetic separation is not a suitable primary beneficiation method. However, encouraging results have been obtained in concentrate purification. At the Boliden complex sulfide ore concentrator in Garpenberg, Sweden, an Allis-SALA Mark III carousel High Gradient Magnetic Separator (HGMS) is used with a small flotation circuit to recover sphalerite lost to the galena concentrate during lead flotation. After four years of refining the HGMS process, there has been an increase in zinc recovery and an enhancement in the quality of the lead concentrate.

Jan 1, 1994