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"When boring a tunnel, homogeneous hard rock is the exception rather than the rule. While contractors can set goals such as meters per month and performance incentives, it is also prudent to plan for difficult ground. A properly designed tunnel boring machine (TBM) can tackle fault zones, water inflows, squeezing ground, or whatever the risk may be. The alternative is not a good one: modifying the machine in the tunnel after bad ground is encountered. Not only does this result in increased downtime, but it also needlessly exposes the crew to the tunnel conditions. In the worst case scenario, the entire operation grinds to a halt.However, an accurate GBR cannot always be obtained, particularly for mountainous, high cover tunnels in remote locations. And even with a thorough GBR, unforeseen geological events can occur. What can be done in these situations? Difficult Ground Solutions (DGS) is ground investigation system with a suite of options that can be added to a shielded hard rock machine or dual-mode, Crossover machine to better enable advance when conditions are unknown or difficult conditions are anticipated.DGS consists of a set of integrated features tailored to a specific project’s geology. The main components of the system allow for ground investigation ahead of the TBM, increased monitoring and methods to keep a machine shield from becoming stuck.In fault zones and squeezing groundIf fault zones or squeezing ground are known or suspected, or if there is even a possibility of encountering them, this can greatly affect the TBM operation. Shielded machines protect the crew from the surrounding rock, and they can bore and line a tunnel efficiently, but in fault zones and converging material their shields can be their downfall. Avoiding a stuck machine is paramount to project success. DGS employs several features to avoid the problem of a machine becoming stuck. The first of these is multi-speed cutterhead drives. These drives effectively give the machine multiple modes of operation—high speed, low torque for hard rock, and low speed, high torque for difficult ground. Designing a machine with high-torque, continuous boring capabilities allows that machine’s cutterhead to restart with break-out torque in difficult ground. The net effect is that the machine can keep boring in the event of a face collapse and can bore through fault zones and running ground where the potential for cutterhead jamming exists. Going one step further, multi-speed gearboxes give the machine the ideal earth pressure balance- (EPB-) type torque if larger sections of soft ground are anticipated.Secondly, TBMs can get through squeezing ground and faults using Continuous Shield Advance. This design utilizes a stepped shield configuration — where each successive shield is slightly smaller in diameter — to avoid becoming stuck in converging ground. External shield lubrication is an added insurance against becoming stuck, using a series of radial ports that can pump Bentonite into the annular space to act as a lubricant in squeezing material.As a last effort, if a machine has already become stuck the TBM can utilize augmented, or “super” thrust. Additional thrust jacks can be added to supply an extra boost in a short stroke, generating enough force to break loose a trapped shield."

Jan 12, 2017

By D. W. McGlashan

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Jan 1, 1968

By D. A. Wheeler

Invented by Pierre Boutin in the early 1960s the column was a complete break from the conventional flotation cell. 1. When used as a rougher-scavenger, the column is excellent. 2. When used as a cleaner, the results can be spectacular. The very first column tests were carried out using it as a rougher-scavenger in a reverse float where silica was floated from iron. It produced a concentrate underflow as good or better than that produced from roughing and scavenging stages in cells, The froth tailing overflow was better than that produced by several stages of cell cleaning. Column scaleup progressed rapidly from the two inch diameter unit to a semi automated 12 inch diameter column on material from the Iron Ore Company of Canada. A change in operating philosophy within IOCC brought all flotation development, column or conventional, to a halt. At that time, IOCC had an exclusive right to the use of the column in Canada in the field of iron ore. We moved into the field of sulphides. A Canadian copper producer sent ore for testing and the results led to their purchase of the first commercial size of column - a 36 inch diameter machine. It was a mechanical disaster. It took several years to raise sufficient funds to return to that mill with our basic 18 inch square unit. It was to be tested and modified in order to learn how to properly design a large column. Originally used as a rougher- scavenger, it had to produce tails equal to the final tailings from this well run plant. It did, and did so while producing a rougher-scavenger concentrate almost equal to the plant final concentrate. It was finally used as a cleaner and produced concentrate 5% higher in copper than the plant final concentrate with equal cleaner tails. This phase of the column development was carried out under very difficult circumstances. The mill superintendent had realized that if he took the froth removal system from our original mechanical disaster and applied it to a conditioner while injecting air, he would have a flotation cell. He had personally applied for patents on this Maxwell Cell. Our development work was done in his mill and as our results became better and better, our difficulties became worse and worse. We finally had to terminate this work. The 18 inch column installed at Mines Gaspé 14 years later was identical to the one removed from Opemiska. The 18 inch column was tried on various ores over the following years and always produced excellent results. However, it was not really a production size unit. We had always aimed for the 72 inch column (72" x 72" x 44' 9"). Prior to this huge machine, we needed the intermediate 36 inch column. The failure of the original 36 inch diameter unit at Opemiska had raised the possibility of short circuiting inside the column as the cross section increased. The first 36 inch square unit was tested in parallel with the proven 18 inch column. If the underflow of the 36 incher was not as good as that of the 18 incher, short circuiting was a possibility in the larger unit. It had been designed for insertion of drop in partitions, four feed points had been provided and the 36 inch column would have become a modular unit of four 18 inch columns. Testing showed the underflows of both columns to be identical. There was no short circuiting in the 36 inch column. Once we had the 36 incher, we had no fear of the 72 inch column. It is permanently partitioned into four 36 inch columns but uses only one set of instrumentation. All the component parts of the 72 inch column come from the 36 inch unit. In spite of our results, the mining community did not believe the column could work. Finally, in 1980, Mines Gasp6 ordered an 18 and 36 inch column for their byproduct molybdenum

Jan 1, 1988

By A. K. Ghose

The increasing application of roadheading machines in the coal industry has prompted the development of an appropriate selection methodology for such machine applications in specific locales. Accurate geological sections and comprehensive rock testing are required for all machine tunneling. Using suitable geotechnical parameters and index tests, sensitive both to excavability and standability of the strata, a classification scheme has evolved to help evaluate the rock mass vis-a-vis application of a given weight-class of roadheading machine. The classification parameters include point load index, brittleness, abrasiveness, average crack density, and ground water, which with assigned numerical ratings, lead to a quantitative global rating of the rock mass. For each rock mass class, the selection of an appropriate roadheading machine is recommended. The paper illustrates the application of the rock mass rating system and also describes simple index tests for evaluating the classification parameters for brittleness and abrasiveness. Manuscript not received in time for publication.

Jan 1, 1983

By R. J. Haydel

The Highland Uranium Operations of Exxon Company, U.S.A. is a large uranium mining and processing complex situated in the Powder River Basin of East-central Wyoming. Surface mining and chemical processing of a large relatively low-grade ore body began in late 1972. An underground mine was later developed and began production in November of 1977. Figure 1 shows the location of our operations. During the planning stages of the project, it was recognized that hiring and retaining quality employees would be a significant problem. Other operations in similarly isolated locations were experiencing high turnover rates and were forced to employ inexperienced and poorly trained operators. In an attempt to attract employees, many of the companies provided mobile home or bunk- house facilities, but these costly peripheral ventures did not prove to be noticeably successful.

Jan 1, 1979

By W. E. Horst

In Part I of this paper we describe two techniques that were employed in the development of mathematical descriptions of the size reduction process which takes place in a ball mill. In Part II we show how the comminution model was imbedded in a process model to effect steady-state and dynamic simulation of a closed-circuit grinding operation. Increasing emphasis is being placed on development of approaches whereby the essential characteristics of a process can be succinctly represented in terms of a mathematical description of the relationships that exist among important process variables. This activity, commonly known as mathematical modeling, predates modern electronic computers: however, these computers with their tremendous computational capability have given new impetus to the whole field. Although the computer is quite helpful in the development of mathematical models, the real value to the engineer lies in the fact that computers represent such a powerful tool for simulating systems described by mathematical models. As a consequence, engineers may simulate and thereby study the behavior of complex. interacting, systems over a broad range of process variables and configurations once appropriate process models have been developed for the sequence of steps comprising the process.

Jan 1, 1970

By William J. Miles

Bentonite Corporation decided to pursue ISO-9002 Registration for our bentonite production for many reasons. We wanted to improve our current Quality System to encompass all business aspects, not just Quality Assurance. We wanted this system to build supplier/customer confidence and provide our customers with all the services that they needed for their business functions: such as Quality Assurance for their needs; appropriate shipping and delivery; appropriate billing; and appropriate sales, technical and management support of our product. These objectives of our Quality System are addressed by the ISO 9000 clauses and requirements. There were additional reasons and expectations for implementing an ISO 9000 Quality System. ISO 9000 registration would develop and aid international sales since the ISO system is a basic requirement in many parts of the world such as Europe and the Far East. It would bring acceptance of bentonite products by new customers and markets Another objective was to develop better trained employees. We hoped that the ISO Quality System would help us reduce costly non-conformances and reduce overall production and operating costs. We hoped to achieve ISO 900 registration before our major customers required it. For example, our major market is use of bentonite as a binder in foundry mold sand systems. The foundries in North America primarily service the automobile manufacturers who have individual Quality System requirements that are being merged with ISO 9000 Standards. As the foundries addressed the automobile manufacturer?s needs, Bentonite Corporation received numerous inquiries and surveys of our Quality System and its conformance with ISO 9000 Standards. Eventually, ISO 9000 Registration will become a requirement to directly or indirectly service this market.

Jan 1, 1996

By Christoph Wels, Michael Royle, Shannon Shaw

Intrinsic remediation is the effect of natural attenuation mechanisms - dilution, dispersion, sorption/precipitation and biodegradation - reducing contaminant concentrations in ground water to specified levels at predetermined compliance points in the aquifer. Current monitoring and modeling for post closure was used to assess the current and long-term potential of intrinsic remediation of contaminated seepage originating from a large reactive (sulfidic) tailings impoundment near Questa, New Mexico. It is concluded that the natural attenuation mechanisms of precipitation within the tailings (as a result of buffering) and dilution/dispersion within the aquifer are currently active and likely sufficient to reduce contaminant concentrations to below state standards in the long-term. Other natural attenuation mechanisms such as sorption and biodegradation within the receiving aquife4s) were not assessed here, but are likely further reducing contaminant concentrations. Active interception and recovery of the seepage water is being maintained until monitoring demonstrates that intrinsic remediation has successfully achieved the level of water quality control required.

Jan 1, 2000

By R. L. Pariani, R. R. Moskalyk

Justifying refinery material handling equipment jointly involves economics and indirect benefits. The simple evaluation method is applicable when either retrofitting facilities or costing new metal refineries. The text includes points of interest regarding equipment selection as an additional guide. Although the copper industry was used as a basis, it is recognized that similarities in material handling may exist within the parallel electrolytic refining and winning of metals such as copper, nickel, lead, zinc, tin, and cobalt. The analysis of four major automatic systems, typically implemented in many tank houses, includes tabulated data plus a detailed description of additional benefits. General information regarding auxiliary material handling equipment and an overview are included for subject completeness. It is suggested that the quantitative and qualitative aspects presented may contribute to the basis for justification of automated material handling. The labor-oriented economics plus related intangible benefits described herein should provide incentives to modernize or replace manual operations where practical.

Jan 1, 1987

By Robert M. Cox

The principal factor that must be determined for the effective design of a coal mine roof bolt support system is the maximum stable tension that can be developed with a given bolt assembly in a particular roof rock. There are four basic types of roof bolt anchorage techniques available: (I) the splitwedge; (2) mechanical expansion units; (3) resin point anchors or grouted expansion units; and (4) the cone shell which is placed in a reamed hole. A study of this problem has been made which includes theoretical analyses, laboratory experiments and field tests. A static free-body analysis of each of the anchorage techniques has provided formulas for predicting the anchorage capacity for a particular rock from the results of standard pull tests. The formulas also provide an insight into the anchorage mechanism of technique and allow for a comparative evaluation of the methods for design purposes. The theoretical analyses also indicate clearly the pertinent variables affecting the anchorage mechanism of each method.

Jan 1, 1977

By P. R. Khangaonkar, G. Bhaskar Raju

Three types of flotation columns were developed with a column dia of 8.0 cm and a length of 160 cm. The first type consists of an ordinary column fitted with a porous plate at the bottom. The second type consists of two electrodes at the bottom to obtain very fine and uniform bubbles generated electrolytically and the third is a combination of first and second types, i.e. to get both electrolytic bubbles and air from the compressor through porous plate. Three different ores were tested-gold tailings for recovery of scheelite, copper tailings (chalcopyrite) and oxide copper ore. In the case of scheelite and copper oxides, good results were obtained with the first type of column itself, whereas the third type column was found fairly effective in the recovery of chalcopyrite. The variables like the effect of reagent concentration, column height above the feed point, feed flow rate, current density, air flow rate, particle size etc. were examined.

Jan 1, 1988

By R. D. Miller, L. Schulte, J. Davenport, D. W. Steeples

Shallow seismic reflection methods were successfully used to delineate the subsurface extent of roof failure associated with the dissolution mining of a 120-m (400 ft) deep and 60-m (200ft) thick salt bed in central Kansas. Surface subsidence at North American Salt's Hutchinson, KS, salt-dissolution well field represents a potential risk to surface structures and transportation facilities. Three intersecting common depth point (CDP) seismic reflection profiles, targeting the subsurface around an actively subsiding sinkhole, possess sufficient resolution to delineate the horizontal and vertical extent of subsurface rock failure associated with the subsidence. The three seismic profiles showed a disturbed subsurface area 90 to 105 m-diam (300 to 350 ft-diam) at a depth of between 60 to 75 m (200 ft and 250 ft). Confirmation drilling verified the interpretation of the seismic data. The seismic reflection method has the potential to resolve disturbed subsurface areas greater than 23 m-diam (75 ft-diam) at this site.

Jan 1, 1994

By Lester G. Rollins

Coal today enjoys a dominant position, serving the energy and metallurgical marketed The measure of success in the market place is, and will continue to be, the price per million BTUs or price per ton delivered to the user. The Coal Industry's remarkable record of price stability since World War II is well known. The next twenty years promise to be equally as challenging. This challenge will be met our president, Mr. Drain, has often stated that, ?The Joy Manufacturing Company is betting that coal will meet the challenge.? To this end, the resources of Joy have been committed to doing its part. Joy's efforts are directed toward a target which has been defined as: 1. Deliver coal to the user at a price of $.15/MBTU or less. or; 2. Deliver coal to the mine portal at a cost of $1.00 or less.

Jan 1, 1966

By P. Schilizzi

The increased impact of mining subsidence in the U.S. coalfields and the recent regulatory constraints legislated by government and state agencies have provoked an intense research effort on this topic by government agencies, coal companies and academic institutions. Subsidence and horizontal strain predictions are a basic requirement if subsidence and its associated effects are to be controlled and contained within acceptable environmental levels. As a result, several such prediction techniques have been proposed or are currently under development to assist coal operators in minimizing the detrimental effects of these surface deformations. VPI&SU has been actively involved in this research effort in the past few years, with particular emphasis on the Appalachian coalfield. During the initial stages of this research a large number of subsidence case studies were collected from the literature, the coal industry and government agencies. In total, data from 32 longwall panels and 60 room and pillar panels were collected. This data bank was used to determine relationships between the basic mining and subsidence parameters, in order to allow the evaluation of the various prediction methods for the Appalachian coal region. Based on this data two subsidence prediction techniques, one based on profile functions and the other on influence functions have been developed. Profile function methods provide a tool for a fast calculation of subsidence on a line across a mine panel. Influence function methods, on the other hand, allow for a more detailed calculation of ground movements, in any mode and at any depth, on a grid or at any specific point. The limitations of the data of the collected case studies, i.e. accuracy of surveys, frequency of monitoring, lack of horizontal movement measurements, etc, led VPI&SU to the initiation of a detailed subsidence and strain monitoring program above a number of active mines, located in three major coal producing counties of Virginia. The aim of this program was to enhance the data base with accurate and complete measurements of surface movements and to allow, therefore, the refinement of the prediction techniques. This paper presents this monitoring program, discusses in detail the results obtained from three specific case studies and provides recommendations for the implementation of the field data in the general prediction methods.

Jan 1, 1986

By John Durkin

A system based on seismic techniques has been developed to detect and locate men trapped underground following a mine disaster. Both theoretical and field studies have been used to generate models to predict the performance of the system. For a strong source, it is almost certain that the miner's signal will be detected if the geophone array can be positioned over a likely area of entrapment. After signal processing, it is highly likely that the location of the miner can be determined within an accuracy of 100 ft (30.5 m). The system is presently operational in a state of readiness in the event of a mine disaster.

Jan 1, 1980

By Joseph W. III Leonard

Most material balances on coal preparation plant flow diagrams are stated in tons per hour of solids and gallons or liters per minute of water. Balances expressed in these terms can be simplified when it is known that 4 gpm (15.1 L/min) of water is about equivalent to 1 tph (0.9 1 thr) of water. Some useful relationships follow

Jan 1, 1991

By C. E. Stack

For the purposes of this presentation, "refractory clay" is intended to include any clay suitable for refractory products and thus represents a description based on industrial application. Other common examples based on use would be white-ware clay, bleaching clay, paper clay, or cement clay. Most users and producers of refractories have specific quality requirements which determine the quality or type of clay that can be utilized. Many clays can however be interchanged or substituted in use by changing manufacturing processes or upgrading less desirable clays. U.S. Bureau of Mines publications (Ampian, 1985) categorize days into six groups. These are kaolin, fire clay, ball clay, bentonite, fuller's earth, and common clay. These are practical groupings based on clay production and usage in the United States. Among these groups bentonite, fuller's earth, and common clay are primarily composed of the minerals, smectite, illite, or chlorite, and are non-refractory. Kaolin, ball clay, and fire clay are commonly used in refractories and thus qualify as refractory clays.

Jan 1, 1986

By J. Wesley Atkins

In considering the importance of lease management and administration, I have decided to approach the topic, Lease Default and Eviction: Action or Reaction, as a three phase presentation dealing with mineral lease administration and management, past, present and future. Though the title may border on the dramatic, it illustrates the real consequences of alternative approaches to property management viewed from my experience in the evaluation, development and implementation of a number of such systems and services in my current position as president of Talco Group Corporation. First, though, let's take a moment and set the stage by giving a few actual examples of why a pragmatic approach is needed in this particular area.

Jan 1, 1983

By Samuel S. Adams

The Grants uranium region of northwest New Mexico is the largest uranium district in the United States (approximately 50% of U.S. production plus reserves) and one of the largest In the world, with approximately 900 million pounds U308 production plus reserves. Deposits of the region are unusual among sandstone deposits for their high content of epigenetic carbonaceous material, generally interpreted but not proved to be of humic origin--that is, co-extensive with uranium in the primary deposits. Virtually all production in the region has been from the Jackpile Sandstone and Westwater Canyon Member of the Jurassic Morrison Formation. The tabular uranium deposits contain, in addition to humate and uranium, significant authigenic phyllosilicates, quartz overgrowths, humate-replaced detrital silicates, and a trace-metal assemblage typical of other sandstone uranium deposit types. Surrounding the deposits in the two sandstone units of the Morrison Formation is an alteration zone within which iron leaching has altered detrital ilmenite-magnetite to residual masses of titanium oxides. Feldspar alteration is locally present within this zone, below deposits in the Jackpile Sandstone, and above those in the Westwater Canyon Member. The feldspar alteration increases in inten¬sity toward the Brushy Basin Member which separates the two sandstone units, ranging from partial replacement to replacement and dissolution of plagioclase and sanidine. Spatial relations among the epigenetic humate, authigenic silicates, and the broad alteration zones that extend from the Brushy Basin Member to and including the uranium deposits suggest that (a) the organic material was involved in the unusual silicate alteration, transport, and authigenesis, and (b) that the humates originated in shales of the Brushy Basin Member. Stratigraphic relations among the Brushy Basin Member and the overlying Jackpile Sandstone and underlying Westwater Canyon Member suggest [in turn] that there was continuous, interfingering deposition controlled in part by contemporaneous basement subsidence along northwest- and northeast-trending zones. Following minor erosion of upper Jackpile Sandstone and deposition of basal organic-rich Cretaceous sediments, the silicates of the Jackpile Sandstone were once again altered by organic-bearing fluids, this time permeating down from Cretaceous sediments and partly obliterated ore-stage alteration.

Jan 1, 2013

By J. Raatikainen, I. Auranen

"INTRODUCTION Sorting technology has advanced rapidly recently. Of the two possibilities particle sorting has advanced especially in introducing new sensors and the use of multiple sensors. The analyzing and computing lead times have also shortened. This has made it a viable technology option for many applications but not for the most important sorting task at a mine; the run-of mine ore. Bulk sorting, however, has advanced in smaller steps, even if the technology has the capability to tackle the run-of-mine ore and offers a high potential to bring mines substantial economic benefits. The sensors, which are useful are restricted by the difficult operating conditions or by the ore characteristics. One of the important features of run-of-mine sorting technology is the major material handling infrastructure required. The capital expenditure can be substantial requiring good understanding of the sortability curve (grade-recovery curve) behavior of the ore. This paper discusses one industrial case, where substantial amount of data measured from the ore feed belt has been obtained. This data was then analyzed for the grade recovery curves obtainable from that ore with sorting. EXPERIMENTAL The XRF measurement used was the FCA device from IMA Engineering (Fig.1). It is a specially built version of XRF designed to operate with coarse material. The measurement was situated at the main belt conveyor taking ore from the primary crusher to the stockpile. The crushed ore was about 80% -300 mm at a capacity of 1100-1200 tph (Fig.2). Measurement times were varied from 30 seconds to a minute. Measurements were obtained over several months.As the XRF is a surface distribution measuring technique, the measurement was first tested upon accuracy and reproducibility against plant daily wet chemical assays and against on-line Courier feed analysis. As there is a varying delay in the ore stockpile, the delay time was used as a variant in the validation. Different measurement times were tested for accuracy. A one minute measurement time gave a total measurement relative standard error, which was both for Cu and Ni below 3%. The results showed also very robust correlations; for Cu, the correlation coefficient was R > 0,94 for one minute measurements over three months and R > 0,86 for Ni respectively. Fig 3. Shows a measurement period of two hours showing substantial feed grade variations (given as relative value; 1.0 represents the mean value during the measurement month)."

Jan 1, 2018