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By F. Varley, J. Whyatt

A variety of dynamic failure cases with regional impact were described at a bump symposium held in 1958. These types of events, while rare, are of particular interest because their ability to impact a large area has disaster potential. These cases can be grouped into two broad classes of events by mechanism. These are (1) a slip along steeply dipping faults and (2) the fracturing of strong strata above or below the coal seam. Both failure modes produce dynamic or “shock” loads on the perimeter (roof, rib and floor) of mine openings. Special consideration should be given to these failure modes in the planning of deep coal mines, since their occurrence is not within the professional experience of many contemporary workers. In addition, their potential is not evaluated by many of the analysis tools commonly used to evaluate hazards in coal mine plans.

Jan 1, 2009

By Andrew Trusiak

Brunswick Mining, employing approximately 1600 employees, is located 40 km south of the city of Bathurst in north eastern New Brunswick. The mine has operated as two lead-zinc operations - the underground mine(No.12) and the open pit mine (No.6). The open pit orebody is presently being' mined by underground methods. It is expected that the No.12 mine will furnish the entire ore supply by the end of 1981. The flotation practice prior to 1971 has been described by Neumann and Schnarr(1) and by Erskine (2). More recently, the current flotation practice has been described by McTavish(3) and deals with some major circuit modifications between 1972 and 1978. The period 1978 to 1980 has seen the completion of. a major flotation cell replacement and expansion program for the No.6 concentrator, and the implementation of computer control in the No. 12 CuPb and Zn flotation circuits.

Jan 1, 1981

By P. Crouse, J. Obermeyer

"INTRODUCTION Site location and history The Holden Mine is a former underground copper mine that was developed and operated by the Howe Sound Mining Company (Howe Sound) from 1938 to 1957. The mine is located in north-central Washington State, U.S., near Lake Chelan in the area shown as Holden Village in Figure 1. Although Rio Tinto never owned or operated the mine, they are managing and funding a several hundred million dollar clean-up to prevent future water and soil contamination and to reclaim the former mine site under the United States Environmental Protection Agency (USEPA) Superfund process. The former mine included an onsite mill and a nearby housing complex for the miners. Howe Sound developed the mine as a series of near-horizontal drifts and tunnels, interspersed with stopes and shafts that connect different mine levels underground. The tunnels that were excavated to develop the mine total nearly 100 km in length.During development of the underground workings, Howe Sound removed more than 230,000 cubic meters (m3) of waste rock from the tunnels and deposited this material in two waste rock piles. Ore was processed from the mine in the onsite mill to produce a copper concentrate that was shipped off site for smelting. Roughly 10 million tonnes of tailings were produced as a by-product of the milling operation, most of which were deposited in three large impoundments (Tailings Piles 1, 2 and 3) directly south of and adjacent to Railroad Creek. Howe Sound closed the mine in 1957. In 1961, the property was transferred to Holden Village, Inc. (Holden Village), a not-for-profit corporation that maintains a year-round community and operates an interdenominational religious retreat in the former miners’ town. With the exception of the patented private land, the remainder of the Site is on National Forest lands and is administered by the U.S. Forest Service. The mine is remote. It is only accessible by boat or float plane from Chelan, Washington, up Lake Chelan to Lucerne, nearly 40 km. Vehicle access from Lucerne to the mine is provided through a 17.5-km-long winding gravel road that climbs 640 meters in elevation. The general site features are shown in Figure 2. Physical setting The Holden Mine is located on the eastern slopes of the Cascade Mountain Range at an elevation between 975 and 1,050 m above mean sea level. Holden Mine was developed adjacent to Railroad Creek, which lies in a glacial U-shaped valley carved into the igneous and metamorphic bedrock with steep-sided slopes (Figure 2)."

Jan 1, 2017

By Chikaosa Tanimoto

INTRODUCTION Bratislava is located at the intersection of important traffic routes, including motor-ways, roads, railways, air traffic, trading, and inland waterway with an important harbour. The construction of the D2 Motorway Bratislava, Lamacska cesta Stare grunty was the last missing section of D2 Motorway and its completion linked the Czech Republic through Bratislava to the Hungarian Republic. Traffic was obliged until its completion to use the Lamacska Road and Mlynska Dolina, which were the most heavily trafficked roads in the city. The section of D2 Motorway to be completed in 2006 was 3,300m in length, of which the SITINA Tunnel was approximately half the length. After putting into operation the transit traffic(motorway) and urban traffic was separated. Transit traffic by passing the town was eased. The junctions D2 with Lamacska Road (Harmincova) and Mlynska Dolina also allowed better use of the motorway for the urban traffic The tunnel construction was specified by the features with the highly weathered and thermally altered granitic rock formation with the overburden of Quaternary sediment of 2?4 m thick, very thin overburden, severely controlled deformation limit and environmental protection. The tunnel had to be excavated beneath and nearby the academic complex area and the zoo, where sensitive facilities exist and animals live in. The tunnel consisted of two tunnels (Tunnel A and B) with the length of 1,415 and 1,440 m, respectively. The overburden thickness was in the range from 10?30 m. The standard cross-section and the one with invert arch were 79.5?81.5 m2 and 92.1?93.3 m2. The excavation took 21 months from September 2003 to May 2005. The construction was based on the concept of NATM. The SITINA Tunnel was the third application of NATM in Slovakia, following the BRANKISKO Tunnel (commenced in July 2003) as the first and the HORELICA Tunnel (in October 2004) as the second NATM practice. To protect the surrounding structures and citizens from tunneling operations, seismic monitoring was performed in association with blasting. The allowable limit of blasting vibration was fixed to be under the particle velocity of 15 mm/sec. The tunnel excavation cleared this limit as expected before construction. In driving through the difficult geological situation the excavation work hit 49 faults, and some of them occasionally caused serious face instability. In principle, the rock formation has been affected by the high hydrothermal effect and the resultant clay filing along faults and joints. The auxiliary reinforcement with the 4?8 m long pipe roofing was needed to protect the vicinity of mining face area. This operation extraordinarily required additional works and time which had not been expected before construction.

By Susanne Pignolet-Brandom

This paper examines the viability of using the QEM*SEM automated scanning electron microscope for the determination iron sulfide and calcite volumetric percentages. The analytical reliability was verified by comparing elemental abundances calculated for fourteen samples using the QEM*SEM volumetric percentages and appropriate mineral compositions and elemental abundances determined by standard laboratory procedures. The abundances were comparable, thus demonstrating suitability of this technique for evaluation of the acid neutralization and generation potentials of mining wastes.

Jan 1, 1990

By Hemendra N. Kalia

To plan a safe and efficient coal mining operation, the design engineer should use all the available information regarding the property to be exploited. The reliability of the mining operation must be as high as possible so that the plants relying on the coal can operate at the maximum design capacity. A good design should incorporate all of the known geological characteristics of the deposit, the structural and physical properties of the coal, as well as the rock which will form the roof and floor of the mine openings. A systematic method is proposed as a guide to insure a mine design that will be safe, efficient and will minimize surface disturbances resulting from mining operations. It is anticipated that the method proposed will result in maximum extraction at perhaps minimum cost to the operator. In general, to develop a mining area, several factors are systematically reviewed: (1) determination of the economic minability of the deposit, (2) the computation of the coal reserves, (3) the marketability of the coal, and (4) the life of the property. In general, boreholes are drilled in a predetermined pattern and geophysical or geological methods are used to log the boreholes. The information so obtained is primarily used to determine the quality and the extent of the deposit and to determine to some extent such geological features as faults, barren areas, washouts, and channels.

Jan 1, 1973

By W. Fletcher

Startup of a new plant is a very interesting time. It generally is also a very demanding and often frustrating period. Startup problems can become serious ii they impede the early achievement of full plant production. Raw materials are wasted, manpower is unproductive, field modifications can be extremely expensive and market commitments may not be met. This paper outlines a well proven and highly successful approach to eliminating many of the problems and frustrations often experienced in plant startup. The procedures and methods summarized in the following paragraphs have been developed over a period of 25 years during which some 90 plants were started up.

Jan 1, 1981

By S. P. Singh

In order to simulate the operation of coal extraction machines, a portable workability instrument has been designed. Initially, the tests were performed with the instrument on modeling material, which were followed by in situ tests on coal in underground mines. The peak and mean cutting resistance and work done to cut a unit length of coal were determined for coal as well as modeling material. In addition, rebound strength and dynamic penetration tests were also performed in situ. On the basis of the cutting characteristics of coal, a "Workability Index" has been developed and its role in the judicious selection of coal cutting machines has been discussed. With reference to prior works and the strength characteristics of coal, it was found that the coal plow may not be suitable for the seams under investigation and the shearer seems to be the only choice. It has been observed that peak cutting resistance and the "Workability Index" in the case of coal as well as modeling material depend upon compressive strength. The peak cutting resistance exhibited certain dependence upon the Schmidt rebound hardness and dynamic penetration strength of coal in situ.

Jan 1, 1984

By S. B. Leonov, K. I. Popov, S. B. Polonsky

The offered technological line includes a flotation pulp air conditioner operating on the impact-mechanical effect and two column apparatuses with a descending pulp-air flow mounted in series. The technology developed makes it possible to increase considerably the valuable component in the concentrate simultaneously with a reduction in energy consumption for the flotation process. The experience achieved with the technology showed the possibility for obtaining sulphide silver-bearing ore superconcentrates with the noble metal content 2-10 times higher than that in the concentrates obtained by the conventional technology. The same results were obtained in the process of calcium-bearing boron-silicate ore-dressing.

Jan 1, 1995

By Liguang Wang, Roe-Hoan Yoon

The thin film balance (TFB) technique was used to measure the equilibrium film thicknesses (H3 between two air bubbles in sodium dodecyl sulfate (SDS) and electrolyte (NaCl) solutions. The results were used to determine the magnitudes of the hydrophobic forces (K232) using the extended DLVO theory. The Km values determined from He measurement allowed us to predict disjoining pressure isotherms, which were found to be in excellent agreement with those obtained experimentally using a bike-wheel film holder. The rate of film thinning was measured at low SDS concentrations with varying amounts of electrolyte (NaCl) added. In general film thinning was controlled by the capillary pressure during the initial stages, while it was controlled by the surfaces forces during the later stages. At low NaCl concentrations, it was possible to predict the rate of film thinning using the Reynolds equation, provided that the driving force was corrected for the contributions from the hydrophobic force, which in turn were determined from the KZ32 values obtained from the He values measured experimentally. At high NaCl concentrations, where it was difficult to measure the equilibrium film thicknesses, the contributions from the hydrophobic forces were determined by fitting the film thinning data to the Reynolds equation. The K232 values obtained using both the equilibrium film thickness and the film thinning measurements showed that hydrophobic force deceased with increasing surfactant and salt concentrations. It was found that the hydrophobic force in foam films was very sensitive to the added electrolyte concentration.

Jan 1, 2005

By Dr. David R. Hargis

Finite-difference digital computer models can be used to evaluate the effects of proposed mine dewatering and depressuring operations on ground-water aquifer systems. The effects of proposed dewatering and depressuring operations can be simulated for both underground and open-pit mining in confined and unconfined aquifer systems. Design of dewatering and depressuring well arrays to accommodate proposed mining operations in a variety of hydrogeologic settings can be accomplished through judicious application of well-documented and tested computer programs that are widely available from government agencies and universities. The speed and flexibility of the computer models can provide an economical means for comparison of alternative mining plans, and can be used to determine the optimum mine plan with respect to dewatering requirements.

Jan 1, 1980

By William Highton

If the economic situation in the Western World evolves on a path similar to that of the past decade, then we Mining Engineers must accept that one of the major cost factors in the production of deep mined coal is going to be that of labour. Whilst not trying to over-simplify matters it does appear that one of the ways of maintaining acceptable coal costs is by obtaining more coal without increasing manpower. One such way could be an increase in the use of the retreat method of mining. The paper theorises and illustrates case studies to show that as the Mining Industry extends the use of Longwall retreat mining systems in coal seams where the risk of spontaneous combustion exists, then the use of bleeder entries should be questioned. In addition to the spontaneous combustion risk, bleeder entry systems where the ventilation flow is not fully controllable cannot be construed as a safe and reliable method of controlling high rates of methane emission. These two major aspects alone should be sufficient ground for Mining Engineers to re-consider the practice of using bleeder entries. An alternative "The Back Return System" appears to offer most of the advantages for controlling the environment, without the disadvantages of the other system.

Jan 1, 1980

From a vast army of workers to gargantuan machines to immense volumes of material being moved, almost everything about the Port of Miami Tunnel (POMT) project points to tunneling on a massive scale. Almost.The star of this underground and underwater show is a Herrenknecht tunnel boring machine (TBM,) nicknamed ?Harriet? by a local Girl Scout troop. With her 12.9-m- (42.3-ft-) diameter cutting head and a total length of 139 m (457 ft), Harriet is boring through thousands of cubic meters of clay, dirt and sand, which is often mixed with coral and other materials, to create two 1,280-m (4,200-ft) traf?c tunnels connecting Watson Island and the Port of Miami (Dodge Island) beneath Biscayne Bay, FL. But in the midst of all of the oversized equipment and machines, a strong contender for the best supporting nod goes to a relatively tiny machine: the Brokk 400. Bouygues Civil Works Florida crews are using the compact, remote-controlled and electric-powered machine to excavate five cross passages between the twin traffic tunnels. The pas-sages will be essential to the safety of people who drive their vehicles under the bay every day.

Sep 1, 2013

By R. Mensah-Biney

The loading characteristics of gold-tetrabromide species onto activated carbon have been evaluated using a completely mixed batch reactor system. The overall loading of gold onto carbon was rapid for the first hour but continued slowly without cessation as a result of reduction of gold. Conventional equilibrium considerations were therefore not applicable. Although loading continued slowly after several days, abnormally high loading capacity values of 10-12 meq/g carbon (650-800 kgAu/tonne) could be attained within 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of [AuBr4l-onto the carbon surface where reduction to metallic gold took place. Elution of gold from the loaded carbon was feasible provided the carbon had not been loaded to too high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon is discussed.

Jan 1, 1992

By Tassos Grammatikopoulos, Mike Johnson, Niels Verbaan

Seabed polymetallic nodules, which contain significant quantities of metals key to electrification such as nickel (Ni), cobalt (Co), copper (Cu) and manganese (Mn) can be processed using several different metallurgical processing options, including direct smelting and subsequent hydrometallurgical refining of the copper/nickel matte; ammoniacal leaching (gas reduction or Cuprion); and acid leaching (often reductive). Many of these approaches suffer from reduced cobalt extraction, difficult physical performance, or overall circuit complexity in general, leading to increased risk to the overall project. SGS has considered the pressure acid leaching of nodules for further investigation, as publicly shared data on this processing route stem from the 1970s and 1980s, and are not always easily accessible. This article details the series of tests conducted and provides updated results obtained — high Ni/Co/Cu recovery with limited manganese/iron (Mn/Fe) — as well as comments on the potential treatment options on the product solution and residue.

Sep 1, 2025

By P. James

"INTRODUCTION Control of target stream acidity is widely used in MIW (mining influenced water). Tailoring pH (a measure of acidity) finds application for controlling key chemistry in both process and waste streams. Traditional lime addition for neutralization and precipitation is most often used but has high reagent costs and results in large amounts of mixed metal sludge requiring costly disposal. A new adaptation of BPS’s patented DEMET™ technology (Dynamic Electrolytic Metal Effluent Treatment) platform offers a potentially improved and “reagentless” alternative to traditional chemical addition for pH adjustment. Electricity rather than chemical addition utilized in BPS’s proprietary approach controllably tailors target stream pH. The method offers a simple, low-cost processing technique yielding cleaner treatment chemistry. BPS’s “green” approach may yield lower operating (OPEX) and life cycle costs and significant reductions (up to 50%) in sludge generation compared to conventional lime treatment. It can also allow new opportunities to generate revenue via selective recovery of valuable processing byproducts. Specific savings and revenues depend on the target site chemistries, details, and processing goals. A more detailed discussion of the process and its operational principles may be found in Reference One.[1] Here application of the BPS treatment to POx (Pressure Oxidation) leaching as an alternative to traditional chemical addition is examined. An example operation process flow for gold mining is considered.[2] Promising processing points for potentially replacing conventional processes with DEMET are noted. The possibilities for lowering OPEX costs, lessening sludge creation, and capturing various valuable byproducts and residuals are examined. Financial life cycle benefit estimates of the principal gains provided by DEMET application to the example operation are noted. Extension and generalization of the analyses to a wider range of scenarios is explored."

Jan 1, 2016

By B. Radwanek-Bak

The assurance of future raw materials supply to the EU mineral industry has become, in recent years, one of the most important tasks of the EU Commission. It is focused on creation a new mineral policy within the EU zone. One of the starting points for this activity was identification of the mineral commodities that are critical for the sustainable development and technological progress. The paper presents the glance to this problem from the National Member level. Domestic mineral reserve base as a possible source of critical raw materials for the EU was shown. Poland cannot be considered as its resource base. The source of these raw materials are not only scarce in Poland, but also they are not produced, and their demand is now - and according to forecasts is going to be in the future - met by imports. The raw materials in question are not considered exactly critical for Polish economy, but they are of limited economic importance. On the other hand, their growth is a best opportunity and at once the need to the future sustainable development.

Jan 1, 2011

By John Rajala

The Otjikoto Gold Mill was commissioned during November–December 2014 as Namibia’s first new gold producer in 30 years. Its operations consist of surface mining with a modern gravity/carbon-in-pulp mill for ore treatment and gold recovery. The initial mill design capacity was 2.5 Mt/a. Its capacity was expanded after nine months of operation to 3.1 Mt/a, and process performance has significantly surpassed design expectations. After startup, the Otjikoto Mill’s throughput and gold recovery ramped up quickly, with both parameters exceeding design after only two months of operation. The robust process performance continued into 2019, with key performance indicators (KPIs) eclipsing design values in almost every aspect of mill operation. The Otjikoto Mill’s gold recovery is exceptionally high, exceeding 98 percent every year following startup, especially considering the low-grade nature of the deposit.

By Amy McBrayer, Andrea Brickey

Limited research has been conducted related to the development of mathematical optimization models for production scheduling at large surface coal mines using the area, i.e., strip, mining method. Increased economic and technical challenges have led to a new interest in production schedule optimization models for these type of mining operations like those currently applied to model underground and open pit mines. While area mines share similar characteristics to both open pit and underground metal operations, neither an open pit nor underground production scheduling model adequately depicts an area mine mathematically. We present an integer programming model with blending constraints and discuss the challenges and opportunities related to the implementation for area mines as well as future research in area mine production scheduling.

Jun 25, 2023

By Kermit Allen

Storing natural gas in solution mined salt cavities appears to be one of the more promising methods being considered by some major gas transmission companies for meeting peak demands. Historically, these companies have been faced with the problem of meeting peak demands when the source of natural gas is located hundreds of miles from the marketing area. Transcontinental Gas Pipe Line Corporation's position was further complicated because some of its offshore Gulf Coast gas supply wells may have to be shut in during hurricane alerts. Transco's solution was to construct. solution mined salt storage caverns adjacent to its pipeline near Eminence, Mississippi. (See Figure 1.) In 1965, Fenix & Scisson, Inc., was engaged by Transco to evaluate the feasibility of storing natural gas in caverns dissolved from salt at selected locations along Transco's pipeline to the East Coast. In June of that year a report was submitted to Transco concluding that this proposal was feasible and recommending several potential sites for storage development. Additional engineering and geological studies followed and in March 1968 the Eminence Salt Dome site was selected and storage construction began that year.

Jan 1, 1971