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By Lawrence Pelham

Introduction Fluorspar demand or consumption has been taken for granted in recent years, except for those that produce, market, or consume the commodity. Thinking used to be that as the steel and aluminum industry goes, so goes fluorspar. This is much less true today. The industry is becoming more dependent on chemical industries that feed primarily off hydrofluoric acid (HF) production. The US Bureau of Mines (USBM) published an assessment of world fluorspar reserves and resources. It created a foundation of valuable data that can be used to monitor fluorspar availability. Celebrations were held this year commemorating the 100th anniversary of the isolation of fluorine. The US and other countries continue to struggle with the controversy of ozone depletion and the effect of fluorocarbons on the atmosphere. Goals for the government's strategic stockpile are being reevaluated. The market for fluorine chemicals is changing and diversifying, making it a challenge to assess and forecast fluorspar/fluorine demand. US production and distribution Fluorspar Fluorspar shipments from US mines reached an all-time high near the end of World War II in 1944 at 375 kt (413,800 st). Eighty-two mines produced more than 453 t (500 st) each, and 10 mines produced more than 9 kt (10,000 st.) each. Illinois supplied 43% of total shipments. Consumption in 1944 was 372 kt (410,200 st), of which 56% was used by steel producers and 32% by HF producers. This was the last year that US production exceeded US consumption. The post-World War II record for fluorspar shipments occurred in 1951 at 315 kt (347,000 st) 58 mines produced more than 453 t (500 st) and eight mines produced more than 9 kt (10,000 st).

Jan 11, 1986

The Sams Creek gold deposit near Takaka in northwest Nelson was discovered in 1974 by CRA Exploration (CRAE) geologists. CRAE recognised the potential of the area and subsequently undertook a comprehensive exploration programme of geological mapping, soil and rock-chip sampling, geophysical surveys and diamond drilling. Exploration defined sporadic gold mineralisation contained entirely within a deformed and hydrothermally altered, peralkaline granite porphyry dyke with a seven kilometre strike length, and up to 60 m thickness. Rock chip samples indicated extensive and economically significant gold grades over approximately one kilometre strike of the dyke at Main Zone prospect. CRAE completed 30 diamond drill holes at this prospect and defined a limited resource. Oceana Gold Limited recommenced active exploration at the Sams Creek Project in late 2002, focusing on improving the geological understanding and known resource at Main Zone. Completion of 1041 m diamond drilling successfully increased the estimated resource to 10.7 Mt @ 2.12 g/t Au containing 729 000 oz at a 0.7 g/t cut off. A further campaign of 1560 m diamond drilling was undertaken in 2003 - 2004 to extend the resource and test the continuity of high grade mineralised zones. Deeper intersections of the porphyry dyke indicated geometrical complexity and grade variability similar to that observed at shallow levels. Recent research suggests that Sams Creek can be geologically classified as a variant of intrusion-related gold systems, and therefore comparable to some other, very large gold deposits. However, due to the rugged terrain and dyke geometry, surface drilling is reaching the limits of viability at Main Zone. If infill drilling continues to be successful then an underground decline may be developed to facilitate further exploration. Potential also exists along strike, where other significant gold anomalies are known but largely untested by drilling.

Jan 1, 2004

Komatsu America International has introduced two new hydraulic excavators. They can work in congested and confined areas. The tight tail swing radius of the PC128US-2 and PC22-8USLC-2 enables the excavators to minimize the work space. The units can operate in confined work settings that are inaccessible or counterproductive to traditional machines. Even the door is designed for tight working conditions. A convex door slides open along the exterior curve of the cab, rather than swinging out on hinges past tracks. And the excavators’ tight tail swing design allows them to load within the track width of the machine.

Jan 1, 2000

Process Simulation and Plant Design of a Mineral Selective Magnetising Flash Roasting Plant Using Neutrons

Sep 13, 2010

By P G. Self, M D. Raven, R A. Eggleton

Investigation of an abandoned quarry near Rowland Flat in South Australia identified asbestiform antigorite as the fibrous serpentine mineral mined during the 1940s to 1978 for filler applications, not amphibole asbestos or chrysotile as reported in earlier investigations. Scanning and transmission electron microscopy (SEM and TEM) and selected area electron diffraction (SAED) of individual fibres were used to confirm the identification. Chrysotile is widely regarded as the only asbestos mineral in the serpentine group. Further work was done therefore, on the geology and mineralogy of the occurrence, and the health implications were reviewed. A zone of antigorite alteration, with associated talc, is traceable for 750 m along strike of recrystallised dolomitic siltstone within Woolshed Flat Shale of Neoproterozoic age. The antigorite formed, in part, by replacement of prismatic crystals of probable tremolitic amphibole. The deposit is proximal to the Williamstown Fault and the serpentine-talc alteration is possibly due to fluids expelled along the fault during late-stage deformation in the Early Palaeozoic Delamerian Orogeny. The antigorite comprises white to pale green bundles of lath-shaped fibres that occur either as randomly- arranged equant patches after amphibole or as cross-fibre veins, both intimately mixed with calcite. Highly fibrous product was mined from the weathered zone where calcite was leached during weathering. Gentle grinding releases fibres with a high aspect ratio (>10:1) that show a wide range of fibre thickness, including a significant proportion of fibres <0.25 ¦m width. Toxicological studies on fibrous antigorite from Poland and Italy indicate that the carcinogenic potential of this form of serpentine is similar to amphibole asbestos. X-ray diffraction (XRD) and fourier-transform infrared (FTIR) techniques readily distinguish antigorite from chrysotile. Determination of asbestiform habit and confirmation of antigorite mineralogy is most reliably done using electron microscopy, preferably with SAED capability.

Jan 1, 2008

By Edward L. McHugh, Charles Sabine, David G. Long

While less than 1% of reported mine accidents are associated with slope stability problems, slope failure accidents were responsible for about 15% of U.S. surface mine fatalities between 1995 and 2003. Small rockfalls, which may involve hand-sized rocks weighing only a few pounds, can cause fatal injuries to workers away from the protection of large machinery. Massive highwall failures containing a million cubic yards of material or more can be fatal even for heavy-equipment operators. As part of an ongoing study at the Spokane Research Laboratory, several remote sensing technologies are being evaluated as tools to assess slope stability and monitor slopes for hazards. An interferometric radar device capable of detecting very small displacements on slopes has been assembled and tested. Radar techniques can provide new tools to augment current methods for monitoring ground control hazards in mines.

By Ray Brandon

The recent introduction of polymer geogrids for ground control purposes in underground mines allows mine operators more flexibility in choosing improved products for several applications. This is evidenced most clearly in longwall recovery operations. Since November, 1994, many mine operators have chosen Fortrac geogrid assemblies for the purpose of securing longwall recovery areas prior to shield removal. Fortrac is a lightweight, strong, and flexible polyester geogrid available in many strengths. Utilizing the "diamond" seaming method, different strengths of Fortrac geogrids are easily fastened together so stronger geogrids may be placed in the most critical areas and lighter geogrids in less critical areas.

Jan 1, 1996

Project developent proceeds by increasingly detailed studies addressing overall project returns through an analysis of the substance, risks and costs associated with the following elements: ò Reserves ò Mining ò Processing ò Infrastructure ò Environmental Impact ò Product Market Computer-based expertise has a potential to ò Capture perishable expertise, making this available for shared access and so reducing the cost of human experience ò Consolidate know-how for optimising process operations, bringing consistency of judgement and advice to decision- making by making the rules, facts and preferences explicit ò Allow assignment of the basis and authority of decisions, so experts can pass routine expertise down the line, freeing their time to generate more. ò Force a review of expertise when creating the knowledge base.

Jan 1, 1989

By Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Mehmet Aksoy, Kagan Ozdemir, Adiguzel Deniz

This paper presents the results of ground vibration measurements induced by blasting during the construction of the Istanbul Kadiköy-Kartal metro tunnel which has been driven at a depth of approximately 20-40 m deep under a highly urbanized region of Istanbul city in Turkey. This tunnel is being constructed by a joint venture group. The formation encountered during the construction is classified as hard and strong rock by laboratory and field tests performed by the joint venture group. Within the scope of the study, for the prediction of the peak particle velocity and to determine the slope of the attenuation curves together with the maximum charge per delay for the S4 shaft tunnels and S12 shaft tunnels of this tunnel route, ground vibration components were measured carefully by using four vibration monitors (Instantel Minimate Plus model) during the advancement of the tunnels which required blasting. The particle velocities and frequency values of all blast events are evaluated according to the United States Bureau of Mines (USBM) and German DIN 4150 Norms in order to predict, and compare the influence grades to the neighbouring buildings, and structures. Also, data pairs of scaled distance and peak particle velocity obtained from 114 records at S4 shaft tunnels and 79 records at S12 shaft tunnels were analysed statistically. Empirical relationships with correlation at the 95 % confidence interval were established for different rock units (diabase and arkose) and suggested for the test sites in order to estimate particle velocity of the ground vibrations.

Jan 1, 2007

By Robert E. Barieau

A list of 163 references to original experimental PVT data on helium is presented for the period 1895 to 1968. The list is complete as of the start of the Helium Centennial Year, 1968, to the best of the author's knowledge. Citations were keypunched for easy updating and are listed alphabetically by author.

Jan 1, 1968

By M. Ge

Signal processing is a major challenge for In-Seam Seismic (ISS) technique. Fourier Transform is an important tool for signal processing such as frequency analysis. However, for ISS signal, localized information, especially time-frequency localization is even more important. Wavelet Transform (WT) provides another approach to study the signal as a function of frequency and time. The objective of this paper is to demonstrate the application and advantages of WT to seismic signal analysis. Both transmission and reflection signals from coal mine void detection experiments are analyzed. The results illustrate that WT appears to be a powerful and convenient method for the in-seam seismic signal processing.

Jan 1, 2007

By Vaughan J. P

The Pegmont deposit is a stratiform Pb-Zn sulphide body occurring in a thin, iron-rich metasedimentary unit situated near the top of the Kuridala Formation, a part of the Mary Kathleen Group of the Middle Proterozoic"Eastern Geosyncline" succession of the Mount Isa-Cloncurry district. The deposit appears to have developed in a shallow basin or depression on a sea or lake floor.Detailed chemical and mineralogical study of seven diamond drill cores through the ore horizon shows that in addition to galena and sphalerite the orebody contains a large range of iron-rich silicates and aluminosilicates.Further, five drill cores selected to represent a section from basin centre to basin edge exhibit clear and systematic chemical and mineralogical changes in the ore horizon in both a vertical and, most importantly, ill a lateral sense.Reconstruction of the sedimentary environment of the ore horizon as a whole shows this to be a silicate facies of a phosphatic, manganiferous iron formation or, more accurately, of "ironstone" in the sense of James (1966, U.S. Geol. Surv. Prof. Paper 440, chapter W).On the basis of both mineralogy and chemistry this silicate facies may be subdivided into three microfacies according to the dominant iron silicates characteristic of each: a fayalite microfacies, a hornblende-clinopyroxenemicrofacies, and a garnet microfacies. Significant Pb-Zn sulphide concentrations are confined almost entirely to the fayalite microfacies.

Jan 1, 1979

By Snehamoy Chatterjee, Sanjay Kumar Palei, Smarak Das

Machine manufacturers’ recommendations on maintenance strategies of capital-intensive draglines are not always based on real data and therefore lead to losses from downtime. This paper proposes a preventive maintenance strategy for a dragline deployed in an opencast coal mine based on reliability-centered maintenance and failure-mode-effects analysis using real operational data. Reliability-centered maintenance replaced a cluster of critical failure components of the dragline while satisfying two specific conditions: (i) the components should be replaced at the earliest mean time to failure (MTTF) within the group and (ii) the time taken to replace all the parts should be equivalent to the maximum downtime within the group. Estimated threshold weightage factor identified twenty-six critical failure components for the preventive maintenance strategy, and clustering of components divided them into nine groups. In a group, the loss that is expected to occur by replacing some of the components before their failure, and the gain by reducing the overall maintenance downtime, has been explained through a cost-benefit analysis. The total net profit generated is calculated as US$200,178. This clustering activity also led to a reduction of annual downtime by 231 h, whose approximate market price as equivalent coal production costs $295,365.

May 28, 2020

By Sivilay Sayavong, David Puller, Julian Gatward, David Hard, Martin Stanley

"AbstractThe Thames Water Tideway Tunnels programme involves the upgrade of London’s combined sewer and storm water system. The first section is the Lee Tunnel between the Beckton Sewage Treatment Works (STW) and the Abbey Mills Pumping Station. This will intercept the overflows currently discharging to the River Lee and has the capacity to store and transfer 350,000m3 of storm water and sewage. The project required 4 shafts and a 6.9km 7.2m diameter tunnel. The shafts are some of the largest ever constructed in the UK, with diaphragm walls up to 98m deep and 1800mm thick. As a result of the innovative methods of diaphragm wall design and construction adopted the 4 very large and deep shafts were able to be excavated and completed safely, with minimal water ingress and with extremely high quality.MVB, a joint venture of Morgan Sindall, Vinci Construction Grands Projets and Bachy Soletanche are delivering the £635m contract with Thames Water’s Project Management Team in a collaborative manner under an NEC contract. Mott MacDonald, Morgan Sindall UnPS & Bachy Soletanche are acting as designers.Some of the important advances in diaphragm walling made included:??Diaphragm wall design to both EC2 & EC7 taking into considering the assessment of chalk stiffness, high hoop stresses, large multiple openings and non-axisymmetric loadings.??Formation of shafts as a faceted circle from a series of overlapping panels, with primary panels up to 7.2m wide demanding concrete volumes up to 1300m3 be poured in one go. Overlapping secondary single bite panels cut into the grade C50/60 concrete.??Excavation of the full geological stratigraphy of London making bentonite management complex.??Panel verticality of 1:300 required over the full depth. The results achieved this and in many cases exceeded expectations with some panels coming in at up to 1 in 800 with the majority at 1 in 400 to 1 in 500. The project is also the first in the Soletanche Bachy Group to take data from the ultrasonic drilling monitor used to check the verticalty in electronic format in order to create 3D CAD as-built drawings.??Each diaphragm wall panel was reinforced over its full depth. Up to 18 separate pieces of reinforcing cage had to be installed in primary panels. Cages underwent a full range of temporary works designs to check that lifting, splicing and placing could all be undertaken safely. Fibreglass was used in the tunnel portals in the shafts to ease breakthroughs."

Jan 1, 2014

The poor reconciliation between the values of estimated and actual grades can cause major economic losses to the mining industry. In a mining operation grade reconciliation is comparing the values of estimated grade calculated in exploration stage with actual grade obtained from blastholes' data. Many different factors affect the degree of reconciliation in a mining operation. In this paper we investigate the factors related to estimated grade which affects the reconciliation process in the exploration stage of the orebody. These factors are the sources of uncertainty in the rest of mine life. In this area the most important factors are inherent variability, statistical uncertainty and systematic uncertainty. A probabilistic model was presented to model each source of uncertainty. The implementation of proposed model was checked and its validity was investigated using real data in an iron open pit mine in Iran.

Dec 6, 2010

By Carl-John Grävare

This paper deals with some of the systems and equipment that are being developed and/or are in use in Scandinavia. The main subject is the development of loading tests on the piles using monitoring equipment. This paper also describes ground improvement using lime-cement columns, expander body piles and steel core piles.

Jan 1, 2000

By John M. Dale

Now that the price of sulfur has reached unexpected high levels, it is little wonder that sulfur from surface ores is again receiving attention. In most instances, it is advantageous for an ore to be at or near the surface. However, it is a distinct disadvantage for sulfur ore to be close to the surface because it precludes the use of the Frasch process. The Frasch process depends on the presence of at least 180 m of uniform overburden to allow pressure injection of superheated water into the sulfur-bearing formation to melt the sulfur. In the Frasch process, sulfur separates cleanly from the gangue underground and comes to the surface in a very pure form. Surface sulfur deposits, particularly those in the Western Hemisphere, exist largely due to volcanic activity, and sulfur separation from the gangue is a formidable technical problem. None of the surface deposits are large compared to some of the Frasch deposits, but at the present sulfur price, they are certainly of economic importance. From the turn of the century until 1975, the price of sulfur was for the most part $18-$28/t. However, with the price of sulfur now over $154/t, there are a variety of technical alternatives to consider for sulfur surface ore separation that may not have been economically attractive a few years ago.

Jan 9, 1981

By J. Baz-Dresch

A custom-designed shotcrete system, consisting of an 8-m3 (10-cu-yd) transit mixer and a shotcrete spray boon carrier, is used by a two-man crew to transport and place up to 25 m3 (32 cu-yd) of steel fiber reinforced, dry, silica fume shotcrete per 11-hour shift. Shotcrete is custom blended by a local supplier and delivered predampened. Mix design and quality control are performed with a computer program that develops and graphs a properly balanced mix based upon the materials sieve analyses.

Jan 1, 1992

By A. S. Murphy, E. V. Manlapig, C. Green, J. W. Parkinson

Historically in Australia and the United States many coal mines deposited raw wash plant fines into large slurry impoundments. At the time the technology and market economics did not exist to make it viable to recover coal from these tailings. Today better technology exist to dredge and clean the tailings and there are circumstances where government regulations and market forces have come together to make coal recovery from these old tailings impoundments economically viable. This paper discusses the processes and equipment being used in tailings impoundment reclamation operations in Australia and the United States, and discusses the economic forces driving these operations.

Jan 1, 2001

By D. Oyler

The National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory (PRL), RAG Pennsylvania and Strata Control Technologies of Australia collaborated in an intensive study of ground behavior, reinforcement performance, and stress redistribution at the Emerald Mine in Southwestern Pennsylvania. The study site was a longwall tailgate subjected to a severe horizontal stress concentration. Field measurements indicated that the stresses applied to the study site nearly doubled during longwall mining, resulting in roof deformations extending to a height of 4.8m (16 ft) above the entry. A computer simulation of the field site was conducted using FLAC-2D, incorporating a broad range of rock behaviors and failure mechanisms. Comparison between the measurements and the simulation showed that the model was able to capture the most significant aspects of the roof and support system behavior, particularly, the extensive slip along bedding that created a partially destressed "softened" zone in the immediate roof. The model also showed that supplementing the normal roof bolt support pattern with cable bolts would allow the entry to survive a further 20-25% increase in the applied horizontal stress. Such information could have very practical application to the design of roof support systems for coal mines.