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By Paul C. Jones

Summitville is an old mining district located south of Wolf Creek Pass in the southern San Juan Mountains of Colorado at an elevation higher than 3500 m (11,500 ft). The Summitville mine site is about 40 km (25 miles) southwest of Del Norte. The current mine, developed by Galactic Resources Ltd. and its subsidiaries in the mid-1980s, is on the north facing side of South Mountain. The area is drained by Cropsy Creek to the east and Wightman Fork to the north, both tributaries to the Alamosa River. Mining in the Summitville area began in 1870 when James Wightman discovered placer gold on what is now known as Wightman Fork of the Alamosa River. The first vein-type deposits were located in 1873 on South Mountain near the current Summitville Mine. Mining began in the district in 1875 and continued sporadically through 1942. Major mining episodes occurred from 1875 to 1894 and from 1926 to 1942. Total gold production from the mining district through 1949 totaled 7.5 t (240,000 oz). An additional 7.7 t (249,000 oz) were produced during Galactic's tenure. Natural degradation of the outcropping sulfide-rich veins in the area and the early mining activity, including development of the Reynolds, Dexter and Iowa drainage tunnels in the late 1890s, have polluted the streams draining the area with heavy metals and acidic water. Names of the various tributaries to Wightman Fork, such as Iron, Alum and Bitter Creek, testify to this natural pollution. This degradation has reduced, or killed, aquatic life in several area creeks, including Wightman Fork, for many years before recent mining activity.

Jan 1, 1993

By Peter Campi, Harry R. Asche, Ian P. Callow, Edmund G. Taylor, P. Scott Smith

The US$1,850 million EastLink project is a 39km tollway and includes twin 3-lane,1.5km long, undrained driven tunnels. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and so to help preserve the unique flora and fauna in the area. This paper describes several of the key issues in the tunnel design and construction, including: the integration of the temporary support design with the Contractor’s tunnel excavation and support procedures, including sharing of responsibility between the Designer and Contractor for support type selection and the production of a project specific rock mass classification system to enable more objective determination of ground conditions. detailed hydrogeological assessments during the design and construction phases to allow confirmation of design loads for the tunnel lining design and the various suite of waterproofing tools in order to meet the project inflow requirements. development of a pre-cast invert solution to the main tunnel secondary lining to enable faster lining construction and to minimize risks to the tunnel membrane associated with fixing reinforcement and construction traffic.

Jan 1, 2007

By F. Sill

The disposal of residual material from processing and combustion of coal, from incineration of domestic refuse and sewage sludges kind to the environment is a prior task for the future. Deutsche Montan Technologie (DMT) has developed a new technique which makes possible to fill-up goaf cavities behind running caving systems in coalmining. In a mixing and pumping station on the surface high concentrated suspensions are produced from the above mentioned materials. The paste is pumped through pipes to the coalfaces and via trailing discharge pipes stretched to the fracture zone in the caved-in goaf. Since three years a special designed plant is working successfully on a coal mine of Ruhrkohie AG.

Jan 1, 1994

By Curt Swanson, David C. Mathy, Dru R. Nielson, Kent VonAspern

In 1997, Central Contra Costa Sanitary District undertook the design of the Martinez East Side Trunk Sewer Improvements Project. Microtunneling was specified for approximately 1,035 meters (3,400 feet) of 600-mm (24-inch)diameter pipeline to be installed through estuarine soil deposits (San Francisco Bay Mud) and alluvium beneath the congested city streets of downtown Martinez, California. Directional drilling was specified for approximately 275 meters (900feet) of 200-mm (8-inch) diameter pipeline in four separate segments to be drilled through bedrock within narrow utility easements between residential properties. This paper presents a case history for the design and construction of themicrotunneling and directional drilling aspects of the project.

Jan 1, 1999

By J. E. Wennen

Screens serve several important functions in CIL and CIP processes for gold extraction. One important screen application known as interstage screening allows slurry to be continuously transfered through a series of CIL or CIP tanks while retaining activated carbon in the tank. In some cases, this has been accomplished by using airlifts to carry slurry containing activated carbon to an external screen which separates carbon as oversize and returns it to the tank by gravity. The undersize slurry advances to the subsequent tank. More recently this has been accomplished using launder screens and Kambalda type screens. These are essentially static screens that rely on air blasts or mechanical sweepers to clear carbon away from the screen surfaces.

Jan 1, 1998

By Joseph Gildner, Donald J. Phelps, Jürgen Laubbichler, Christopher Tattersall, David McAllister

The Beacon Hill Station and Tunnels portion of the Sound Transit Central Link Project consists of one mile of twin rapid transit tunnels, an underground station, portals and ancillary works constructed in an urban environment. Presently under construction, the station will set a number of North American firsts including deepest soft ground excavation carried out using the Sequential Excavation Method (SEM).Located in highly variable glacial soil deposits ranging from soft, water bearing sands to stiff, slickensided clays, the station complex and running tunnels proved to be technically challenging during design. Meeting these challenges necessitated an extensive geotechnical investigation, a trial shaft, and state-of-the-art numerical analyses to develop ground conditioning, pre-support, excavation support and structural design. A comprehensive risk identification and mitigation program, and innovative procurement strategy were incorporated into the design and contract bid documents.

Jan 1, 2005

By P. Otto, G. Borm, Th. Dickmann, F. Amberg, R. Giese

Based on many years experience, the well approved Tunnel Seismic Prediction System (TSP) has been substantially enhanced for online geological prognosis in underground construction. The method provides high resolution seismic images of the rock mass ahead of a tunnel face via an array of standard anchor rods. These contain3D-geophones and can routinely be installed during the excavation process. A further outstanding feature of the system is the newly developed high frequency repetitive seismic source which can easily be fixed at a tunnel boring machine. A user-friendly software package enables online data acquisition, processing, 3D-visualization, and interpretation.

Jan 1, 2001

By L. C. de Kooker, K. Esmaeili, I. Musonda, M. Ferentinou

This paper presents the results of an investigation into the effect of pore pressure regime on the factor of safety (FS) and the anticipated critical failure mechanism for a fly ash storage facility. In this study, pore pressure measurements from standpipe piezometers and pore pressure estimated from seepage analysis were used for a comparison of the estimated FS for a fly ash slope. This comparison was applied for static and seismic scenarios. To account for the uncertainties resulting from the limited data available and support a qualitative risk assessment evaluation, a probabilistic analysis was performed. The slope stability analysis was conducted in 2D and 3D, adopting the limit equilibrium analysis approach, and a finite element seepage analysis. The results suggest consistency of failure surfaces for 2D and 3D and an increase in FS values of 5 percent for the 3D approach, limitations of standpipe piezometers. The study demonstrated the sensitivity of the FS value, and the implication of adopting representative material properties, and water table levels, especially in cases where limited data are available, and assumptions need to be made to assess the long-term stability of a fly ash dam facility.

Aug 1, 2024

By Christopher Mark

Successful longwall gate entry design requires control of both vertical and horizontal stresses. Vertical, or overburden, stresses are most severe in the tailgate where they are concentrated by longwall panel extraction. Horizontal stresses, which are generally tectonic in origin, can be highly destructive during the development and headgate phases of longwall mining. The goal of this paper is to present the current state-of-the-art in detecting and controlling horizontal stresses. The information presented was collected through site investigations at 45 U.S. longwalls and an international literature review. The paper begins with a discussion of the present knowledge of regional in situ stress fields in the U.S. A review of available underground stress measurements from coal mines is presented, along with data collected by structural and petroleum geologists. The combined evidence indicates that a persistent ENE-EW trending stressfield is present throughout the eastern coalfields. Experience with horizontal stress in longwall mines is addressed next. The paper focuses on the northern Appalachian region, where the effects of horizontal stress have been most evident. Three case histories are discussed in detail, and the solutions each developed are highlighted. Observations made in the Southern Appalachian, Alabama, and Illinois coalfields are also described.

Jan 1, 1991

By A. Haghighat

A risk analysis on mine fires for all U.S. underground coal mines from 2000–2012 was completed to identify locations that have a high risk for fire incidents. The data for this analysis was extracted from the Mine Safety and Health Administration’s (MSHA) mine fire accident reports database. After identifying fire incidents from this database, a risk matrix was developed for underground locations that showed a significant propensity for fire incidents. This matrix associates the hazards and risks with the severity and frequency of their consequences at each location. These significant mine areas will be the concentration of future studies in fire behavior, suppression techniques, and simulation methodologies. INTRODUCTION Fires in underground mines pose significant hazards to personnel because of inherent restrictions to movement and limitations to egress routes. Despite improvements, mine fires remain serious hazards in underground coal mine. In order to better mitigate the risks from fire hazards in the modern underground mining environment, a better understanding of where fire events occur must be gained. The following paper presents an investigation on the number of fatal and non-fatal incidents in underground coal mines fires from 2000 to 2012. Three phases of risk assessment (i.e., risk identification, estimation, and evaluation) were applied to the recorded fire events from the MSHA incident database that occurred during this time period. Using this process, a fire hazard was first defined. This definition was then used to identify any incidents that had occurred as a result of the defined hazards. The seriousness of the injuries and damages were finally quantified for each incident though an estimate of severity and frequency and then aggregated according to underground location (ISO, 1999; Van Duijne, 2008). Using this approach, locations prone to incidents resulting from fire hazards were first identified. The risk for the occurrence a fire incident in general was then estimated for each of the identified locations. The results of this assessment will be used to improve fire simulation techniques for the identified, high risk underground locations. RISK IDENTIFICATION A risk for this assessment was defined as any single occurrence of a fire initiated by the ignition of gas, dust, or electricity. Each recorded occurrence of such an event in the MSHA incident database was counted as a single fire incident. Both non-fatal incidents that were reportable but did not result in a fatality and fatal incidents that fell into the aforementioned criteria were counted. Incidents in the MSHA database that were already classified as “generic” were not considered. The remaining incidents were then totaled and aggregated according to the underground location in which they occurred. In previous studies, a number of locations, which are listed in Table 1, were highlighted as high fire hazard areas (McDonald et al, 1980; Pomroy et al, 1995; De Rosa, 2004). These locations were used to group the fire incidents extracted from the MSHA incident database. The compiled numbers of non-fatal and fatal underground coal fire incidents from 2000 to 2012 are displayed in Table 1.

Jan 1, 2019

By Calvin J. Konya

An investigation was performed to determine conditions which optimize fracture formation between blastholes used for purposes of pre-splitting. Experiments-involved high-speed photography in Plexiglas models and radiographs in sandstone models. Additionail data was obtained from full-scale pre-split blasts. Pre-split fractures between blastholes were found to form as a result of gas pressure and were affected little, if any, by stress wave interactions. Pre-splitting was effective with short period delays of 25 milliseconds or less, and did not require instantaneous initiation of blastholes. Significant reduction of ground vibration resulted with the use of delays

Jan 1, 1980

By CHENGLONG XU, HAORAN LI, YALI FENG, JINRONG JU, Shunliang Liu

In order to realize the resource utilization of spent hydrodesulfurization catalyst, a solvent extraction-oxalic acid precipitation process is studied in this paper for efficiently recovering vanadium, nickel, and aluminum from the acid leaching solution of spent hydrodesulfurization catalyst. The process conditions for extracting vanadium with Cyanex 272 and precipitating nickel using oxalic acid as a precipitation agent were explored in detail. The results show that vanadium (IV) in the sulfuric acid medium containing nickel and aluminum was efficiently and selectively extracted by Cyanex 272. After three-stage countercurrent extraction, the extraction efficiency of vanadium was 99.76%, and the co-extraction efficiencies of nickel and aluminum were only 2.47% and 1.87%, respectively. Thermodynamic calculation shows that the extraction of vanadium (IV) from the sulfuric acid medium with Cyanex 272 is an endothermic reaction. The innovative method of oxalic acid precipitation was used to recover nickel from the raffinate, achieving selective extraction of nickel from the solution containing a high concentration of aluminum. The precipitation efficiency of nickel was 98.58%, while that of aluminum was only 0.75% under optimal conditions. The proposed flowsheet for the separation of vanadium, nickel, and aluminum from acid leaching solution may provide a new idea for the comprehensive recovery of valuable metals from spent hydrodesulfurization catalyst.

Nov 30, 2022

By Y. C. Kim

The results from a retrospective study are described in this gaper in which she past development drilling activities were investigated using geostatistics. The purpose of the study was to determine the amount of savings in drilling cost that could have been realized through the optimal placement of sequential drill holes using geostatistics. Out of 144 DDH's that were in place within the study area, the results showed a possible elimination of 34 DDH's without any reduction on the confidence interval of the global reserve estimates. If the incremental savings from one drilling campaign to the next were considered, however, the amount of percentage savings were even greater. Other interesting results from this study were; 1) tangible demonstration of the importance of a proper geologic delineation within the study zone, and 2) the robustness of the obtained experimental variograms from the rather early stage in development drilling.

Jan 1, 1981

By James H. Nulty, Joseph S. Roti

INTRODUCTION During a recent panel discussion on the topic of millwater antiscalants, the question was posed: "What would you like to see in the future?" Answer: 'We need an antiscalant that: can be fed without a pump (no maintenance), functions on residual basis (no fault), can be tested for colorimetrically in sub-part-per- mi 11 ion concentrations (no guessing) and will recycle back to the mill from tailings (no cost).” Impossible? Based upon today's level of technology, such a product does not exist. However, a few of the qualifications listed above are certainly food for future thought. Meanwhile, progress is being made in upgrading three essential elements in this critical area of ore processing. They are: 1. Antiscalant reagent research and development. 2. On-line monitoring programs. 3. Reagent storage and feed systems. The objective of this paper is to out- line the current direction being taken in each of these areas and to present case histories as examples of how theory has been applied in field situations to better improve operations. LABORATORY SCREENING TESTS Recent technical papers have explained the various generic chemical raw materials which are available in the marketplace. While the merits of each chemical component are open to debate, the processes used by most major reagent suppliers to evaluate products in the laboratory are fairly standard. Common techniques incorporate both static and dynamic conditions in the search for the most cost effective product. Static Test Perhaps the most common test procedure used is based upon NACE Standard Test Method 03-74, which is "a laboratory screening test to determine the ability of scale inhibitors to prevent precipitation of calcium sulfate and calcium carbonate from solution." The objective of this test is to measure the change in calcium ion concentration in a container of saturated stock solution prepared from calcium chloride and sodium carbonate which is heated in a water bath. After 12 hours at constant temperature (160°), the mother liquor is pipetted into a beaker and a titrated for gm/l of unprecipitated calcium ion. A simultaneous test is performed on stock solution with antiscalant added. The results are then charted to determine the most effective antiscalant (with respect to preventing precipitation of calcite). It should be noted that this procedure examines only the ability of a chemical additive to retain calcite in a saturated solution where thermal stress is applied. This is commonly referred to as sequestration or stabilization. It has been documented that products which act in this manner (i.e., inorganic and organic phosphates) are good scale inhibitors. However, low molecular weight anionic polymers function in a much different manner by distorting calcite crystal size, shape and charge density, thus preventing scale formation. Because of this different mode of operation, static tests may not prove conclusive where polymers and sequestrants are being compared. The simplicity of this test makes it easily adaptable for field use, although modifications are often made.

Jan 1, 1986

By P. Moran

A promising and increasingly popular tailings management strategy is to place cemented tailings underground as backfill. The placement of cemented tailings results in enhanced geotechnical stability and a purportedly more geochemically stable tailings form with lower leaching potential. Conventional subaerial tailings management can negatively affect water quality if weathering causes acid rock drainage and metal leaching (ARD/ML) to occur, whereas cemented tailings can limit leaching via porosity and permeability reductions and contribute alkalinity to limit the potential for ARD/ML. Cemented tailings backfill appears to be better, but how can this advantage be proven? Currently, cemented tailings backfill is utilized at mining operations internationally, but there is limited guidance on performing geochemical characterization and associated evaluation of the potential impacts to water quality. As a result, various approaches to simulating the leaching behavior of cemented backfill have been utilized, including some methods that are unlikely to represent weathering under site-relevant conditions. American Society for Testing and Materials (ASTM) Standard Test Method C1308-08 is a diffusion testing method initially developed to assess constituent release rates from solid nuclear waste forms. ASTM C1308-08 uses intact cylinders that more closely represent actual backfill than methods that require crushing or size reduction. It is widely believed that leaching from actual cemented tailings is controlled by diffusion through small pores that exhibit limited exposed surface area, making diffusion testing particularly applicable to cemented tailings placement.

Feb 27, 2013

By G. A. Calboreanu

The deterioration rate of any metal or alloy is increased in a erosion-corrosion application because the passivated surface layer is removed by the solid particles contained in the pumping fluid and the material surface becomes corrosion active again. Numerous attempts were made to engineer a stainless steel with higher hardness and unaffected corrosion performance. Alloys of special interest in such an area are the duplex stainless steels particularly the CD4MCu material which has the capability of being hardened due to its ferrite-austenite microstructure. Unfortunately, the CD4MCu with higher hardness comprises different intermetallic compounds which will increase the corrosion rate. The paper is analyzing the erosion-corrosion performance of a new type CD4MCu with 32% higher hardness and superior wear performance. The corrosion performance of this new alloy is better than the corrosion performance of the common CD4MCu material which the industry could supply. The corrosion effectiveness was evaluated with the Huey test, the potentio-dynamic anodic polarization test and the weight loss test whereas the erosion resistance was established with a low stress ball-on-disk type apparatus. The Wilfley hard CD4MCu material had 39% lower weight loss and 32% smaller volume loss than the common CD4MCu alloy The hardness range of the centrifugal pump parts poured and processed with the Wilfley hard CD4MCu is 320-350 HBN versus 250-255 HBN hardness of the common CD4MCu. After approximately 18 months of experimentation and field testing it was clearly established that the life time of the Wilfley hard CD4MCu is higher than the common CD4MCu and consequently centrifugal pumps were supplied to different customers in North and South America. India and more recently Australia. Sincere thanks to all the A.R. Wlifley & Sons Inc. and Western Foundries Inc. employees who supported and help to implement this work. special thanks to George Wilfley. Dave Cobb. Bill Becker Sr. and Wayne Taylor

Jan 1, 1997

By Paul L. Bearden

The accumulation, handling, and utilization of sludges formed from wet process phosphoric acid is one of the major problems in the industry. The purpose of this paper is to explain some of the considerations and techniques that can be employed to provide some measure of control over the problem. An acid made from a Central Florida phosphate rock is used to illustrate the effects of one process design approach used to provide one type of control. Other approaches or techniques are discussed on a general basis. In every case, the discussion is purposely limited to conventional dihydrate processing in which phosphoric acid is produced from the filter at a strength of approximately 30% P205 and is subsequently concentrated to higher strengths such as 44 and 54% P205.

Jan 1, 1966

By R. Hagemeyer

In North America, the paper industry is by far the largest consumer of coating and filler mineral pigments. Present use is at an annual rate of 5.5 million metric tons with a value of $660 million. Current estimates are 65 percent is used in coating and 35 percent in filler applications. During the past decade, the switch to alkaline papermaking has provided the opportunity to substantially increase filler levels while maintaining paper strength. As a result filler consumption has been growing at a late in excess of 15 percent yearly. Unfortunately, within a few years, mandated recycling could slow or even reverse this trend. The critical issue is finding an economically viable method for recycling the mineral pigment and/or minimizing the disposal problem

Jan 1, 1994

By N. Aouad

Dump truck operators are exposed to whole-body vibration (WBV) levels that exceed the International Standard Organization (ISO) 2631-1. The WBV level measured by RMS acceleration value, for operator comfort, and long-term health and safety is under 0.315 m/s2 by these standards. However, fundamental research by Frimpong and Aouad (2009, 2012) and field experimental study by Kumar (1999) have shown that operators are exposed to extreme WBV levels exposing them to injuries and musculoskeletal diseases in the long-term. These extreme WBV values in the vertical direction are equal to 3.56 m/s2, 1.12 m/s2 and 0.87 m/s2 for the operator?s seat, lower-back and cervical regions, respectively. This paper will outline current research to solve these problems. Keywords: WBV, Truck Vibrations, MSC.ADAMS, Virtual Prototyping

Feb 27, 2013

By M. Misra

The dissolution of mercury during gold cyanidation is the cause of many environmental, health and processing problems. A study was undertaken to find a suitable reagent for the removal of mercury bearing complexes from the leach liquor. Removal of mercury from synthetic solutions and process water from a gold mine was investigated using sodium sulfide, sodium and potassium dimethyl dithiocarbamates as precipitating reagents. The results have shown that efficient mercury removal could be achieved by addition of potassium dimethyl dithiocarbamate (KDTC), by formation of stable mercury compounds. The resultant mercury-potassium dimethyl dithiocarbamate precipitates are stable under present plant operating conditions and do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is also possible to stabilize the mercury in the heap during cyanidation by adding dimethyl dithiocarbomate.

Jan 1, 1998