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By S. J. Schatzel, W. P. Diamond

High methane emissions originating from the active face areas and from the fractured formations overlying and underlying the mined coalbed can adversely affect both safety and productivity in underground coal mines. Since ventilation alone may not be sufficient to control the methane levels in the longwall mining environment, gob gas ventholes have become a standard supplementary methane control option in many mines. As mines progress into deeper and gassier coalbeds, or as longwall panel size increases, ventilation and gob gas ventholes together may not be sufficient to maintain methane levels within statutory limits. To decrease the risk associated with methane emissions under these circumstances, in-seam horizontal methane drainage is often used to reduce the gas content of the coalbed prior to mining. Horizontal methane drainage borehole completion designs, drilling strategies, and degasification lead times may need to be adjusted for site-specific conditions due to mine design, geology, and the gas content of the coalbed. This study investigates different horizontal methane drainage borehole patterns, borehole lengths, and degasification times prior to and during panel extraction to evaluate their effectiveness in reducing methane emissions using a "dynamic" 3D reservoir modeling of a 38 1-m wide longwall panel operating in the Pittsburgh coalbed. Results of this study showed that dual and tri-lateral boreholes are more effective in decreasing emissions and in shielding the entries compared to fewer shorter, cross-panel, horizontal boreholes parallel to the longwall face. Modeling results showed that after 12 months of pre-mining methane drainage, the average longwall face emission rates can be reduced by as much as 10.3 m3/min and 6.8 m3/min using tri- and dual-lateral boreholes, respectively. It was also shown that if pre-mining methane drainage time is short, it is important to continue methane drainage during the panel extraction to maximize reductions in longwall face emissions since additional face emission reductions achieved during this period can be comparable to pre-mining degasification.

By Jake Gibson

"As one of the most pressing and important political debates of this century, climate change has captured global attention and is forcing governments to take action toward decreasing greenhouse gas (GHG) and carbon emission levels below what was previously thought to be necessary. With the ever-increasing price of diesel fuel, accompanied by the popular topic of carbon taxes and greenhouse gas emissions, the mining industry is looking to industry specialists for assistance. The benefits of a no-idle policy reach far beyond carbon reduction and fuel savings, ranging from decreased maintenance to increased engine life. With products like battery-powered ac systems and diesel-fired heaters, going noidle is easier today than ever before. With both systems being manufactured to withstand the harsh environments of the mining industry, the end user will see a seamless change from conventional, inefficient belt-driven systems to future, standalone mobile equipment HVAC.The history of GHGs and climate changeIn 1896, Svante Arrhenius first claimed that the combustion of fossil fuels may eventually result in enhanced global warming, but not until 1955 did Gilbert Plass draw global attention to global warming by summarizing that adding carbon dioxide to the atmosphere would intercept infrared radiation and thus warm the earth. Then in the early 1960s, Charles Keeling developed modern technology to produce concentration curves for atmospheric CO2 (Fig.1).In 1988, the Intergovernmental Panel on Climate Change (IPCC) was founded by the United Nations after acknowledgment of a rising global annual temperature. The IPCC consists of more than 2,500 scientific and technical experts from more than 60 countries. Because climate change could not be solved by a single country, the Kyoto Protocol was negotiated in 1998, requiring all participating countries to reduce their GHG emissions by at least 5 percent from the 1990 levels. The Protocol was signed by 186 countries in 2001 (since then several countries have retreated from the agreement, including the United States). In 2002, the Bush administration announced a policy for climate change relying on domestic, voluntary actions to reduce the "greenhouse gas intensity" of the United States economy by 18 percent by 2012. The U.S. still attends the Kyoto conference of parties (COPs) but does not participate in negotiations, as it is not bound by its terms."

Jan 1, 2014

By Larry Stearns, Lori Tiefenthaler

Remediation of contaminated soil represents a significant market for application of Deep Soil Mixing (DSM). Eighty-one percent of U.S. Environmental Protection Agency (EPA) Superfund Program’s site remedies have involved contaminated soil. Contaminated soil is frequently treated by In-situ Solidification/Stabilization (ISS). ISS treatment of contaminated soil involves mixing binding agents into soil using DSM techniques. DSM is a core business for many DFI members. Members may improve and broaden their services to clients by learning about the recent ISS treatment of contaminated soil at a Superfund site. ISS treatment is part of the EPA-selected remedy for a Superfund Site in the metro New York City area. The property has seen heavy industrial use for more than a century. Soil at the site is contaminated with a variety of volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs) including coal tars and heavy metals, principally arsenic and lead. Beginning in 2017 and continuing through 2018, approximately 150,000 cubic yards (115,000 cubic meters) of soil will be treated by ISS at the case study site. Portland cement and slag cement are mixed into the soil by DSM techniques using GPS guided excavators to immobilize the hazardous constituents within the treated soil. ISS treatment by DSM will contribute to redevelopment of this valuable property. This paper will describe ISS constructability and performance, case study grout mix design with geotechnical results for strength and permeability, and deep soil mixing techniques. INTRODUCTION In-situ solidification and stabilization (ISS) is a deep soil mixing (DSM) technique applied in the environmental remediation field to physically encapsulate, or chemically bind, contaminates of concern such that the impacts to human health and the environment are mitigated. Common remediation applications of ISS include mixing cementitious reagents into contaminated soils to form a monolithic mass with desired performance characteristics, and the installation of vertical subsurface walls designed to control groundwater movement. A key characteristic of ISS is that the contaminated soils are treated in their existing location at the project site and then are left in place after treatment. Typical performance characteristics of the ISS treated soils include improved unconfined compressive strength (UCS), reduced hydraulic conductivity (HC), and reduced leaching potential of soil contaminants. Increased shear resistance of the treated soil may also be a performance requirement where seismic loading is a concern.

Jan 1, 2018

By Carl D. Ealy

Work is being done to web enable the FHWA Deep foundation Load Test Database. Originally designed to function in the client server environment via modem, access to the database both for data maintenance and user queries has been upgraded to take advantage of the Internet and current and future information technology innovations. The DFLTD will be part of an Automated Geotechnical Information and Design Aid System, the object of which is to assist those involved with managing and maintaining our nation's highway infrastructure. The system will also meet the needs of university and other research institutions for a statistically meaningful source of high quality data for the development and verification of improved analysis methods, in-situ testing methods, etc.

Jan 1, 2002

By Leonhard Weixler

The Bauer company was founded in 1790 by coppersmith Sebastian Bauer in Schrobenhausen, a small town north-west of Munich. The original workshop business carried out works including repairs to church roofs and brew kettles. Later the company expanded its operations to encompass water pipe installation, which it continued through to the 1980s. In addition to installing water pipes it then also began drilling wells, which were sometimes constructed using very simple methods, such as tripod frames (Figure 1).

Jan 1, 2011

By J. Danoczi

Specially designed X-ray machines are used extensively on diamond mines for the recovery of diamonds from ores. These machines are extremely expensive and, at present, there are no reliable methods of determining if the equipment is performing efficiently. The objective of this work was to manufacture translucent X-ray diamond simulants, which would emit varying but known luminescence signals when exposed to X-rays. These X-ray diamond simulants could then be used to determine the efficiency of diamond recovery operations.

Jan 1, 2008

By Kwong. Kyei-Sing

Gasification is a process that converts a carbon feedstock into synthesis gas (CO+H2). Slagging gasifiers operate at high temperature and pressure and in a corrosive-wear environment from the slag. Cr2O3-based refractory linings are used to protect the steel vessel that comprises the gasifier from the aggressive gasification environment. Increasing service life of the gasifier is one of the keys for wide spread development of this technology. In support of the goals, research on the gasifier atmosphere, the slag chemistry, the interaction of Cr2O3 refractory with different feedstock mixtures (e.g., coal and petcoke) were characterized by post mortem analysis of bricks from service in gasifiers and thermodynamics simulation of the environment. Examples demonstrating how thermodynamic calculations can explain the post mortem results and make predictions of material interactions will be given. Attention is placed on the possibility of Cr+6 in different feedstock mixtures and operating conditions.

Jan 1, 2010

By Bruno Gemmi

The objective of the ? 200 million ($280 million) project Parma Railways Station-Urban Transformation was the reconnection of the North and South parts of the town by constructing an 80 m (250 ft) wide sunken artery passing under the four double railway tracks of the station without any impact on train traffic. The site of the project, adjacent to the Parma River, presented water seepage problems at any excavation depth. The use of conventional large diameter bored pile machinery was not allowed by the Railway Authority because equipment dimension and construction phases do not comply with train traffic safety regulations. Foundations for the bypass were thus constructed by minipiles nested into jet-grouted soil using machinery operating within the existing head room and at a safe distance from the tracks. Jet-grouting treatment reached depths of 25 to 28 m (80 to 90 ft) from tracks? grade and embedded minipile-heads were terminated at 2 to 3 m (6.6 to 10 ft) below grade. Load tests on minipiles were pushed to failure. Failure occurred at a 240 t (265 t) load without breakage of the bond between the jet grouted soil and the minipiles. A 0.93 MPa (135 psi) shear resistance ??? between minipile steel casing and the jet grouted soil was measured prior to the failure of the steel casings. Overall measured foundation settlements were well within expected values and were considered insignificant.

Jan 1, 2011

By G. L. Neumann

Owing to the need for additional sources of supply of both zinc and lead following World War II, the Bureau of Mines investigated many abandoned lead-zinc mines in the eastern United States. A series of shallow veins in south-western St. Lawrence County has long been a subject of speculation. These veins, which average about 4 feet in width and cut across the bedding of the country rock at right angles, are filled with calcite-carrying galena and sphalerite. The deposits have been worked sporadically during the last 115 years. From 1837 to 1852 the Coal Hill, the North, and the Victoria mines near the village of Rossie were at their peak of activity. Other calcite veins were prospected and a small production was realized. The Bureau of Mines began diamond drilling May 1, 1950, under the general supervision of McHenry Mosier, chief, Mining Branch, Bureau of Mines, Region VIII, and under the immediate supervision of the author) who was project engineer, following the preliminary examination by Robert S. Sanford. A total of 3,870.2 feet was drilled in 18 holes on four of the numerous deposits scattered over Macomb and Rossie townships. Drilling was completed September 21, 1950.

Jan 1, 1952

In this issue, the Bureau of Mines announces the availability of the latest of its Mineral Perspectives series: ?MP-4, mineral Industry of Western Europe." This publication describes the mineral industries of 19 Western European countries. For readers unfamiliar with this new series, reproduced below and on the two succeeding pages, is the section dealing with the mineral industries of France. Information regarding acquisition of this publication is found inside the back cover of this issue. FRANCE France is a moderately important producer of minerals, including iron ore, coal, potash, fluorspar, and uranium. In addition, France is a significant processor of imported minerals, chiefly for its own consumption. In general, it has exportable surpluses only of a little iron ore (low-grade ore exported to Luxembourg) and some nonmetallics.

Jan 1, 1977

By Yi Luo

The efforts to mitigate longwall subsidence influences on various residential and farming structures by many coal mining companies have been successful in the recent years (Luo, et al, 2003). The successes were largely dependent on the accurate subsidence predictions, correct assessments of potential influences, appropriate design and implementation of the mitigation measures. However, such efforts for protecting large industrial structures are still very rare. In this paper, the successful assessment and mitigation of the subsidence influences associated with a very intensive dynamic longwall subsidence process on a large workshop are presented.

Jan 1, 2005

By Joe Roby

Rolling disc cutters are the business end of hard rock and mixed face tunnel boring machines (TBMs). Since their first successful employment on a TBM over fifty years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates higher and cutter costs lower than ever before, proving the value of investment in cutter development. This paper describes recent improvements in disc cutter components including cutter ring materials and processing, as well as improvements in lubricants, bearings, seals and cutter condition monitoring. These developments have resulted in more reliable cutters capable of operating in a wide range of geological conditions. Ultimately these improvements result in a better value for both contractors and project owners.

Jan 1, 2008

By M. A. Elliott, H. H. Schrenk, L. B. Berger, John C. Holtz

"INTRODUCTION Diesel-powered locomotives designed specifically for underground operation were used in the construction of some of the tunnels that comprise the Delaware Aqueduct in New York State. Before this there had been limited use of Diesel-powered equipment such as trucks, bulldozers, and shovels in tunnel construction in various parts of the country, but this equipment was used without modification for underground use and, in some instances, appar¬ently without due consideration of the hazards that might be created by the introduction of fuel-burning equipment into confined underground spaces.As certain definite advantages were apparent if Diesel haulage could be used in tunnel construction in some sections of the Aqueduct, the contractors who were to construct the tunnels in these sections were desirous of using, this type of haulage equipment if it could be used with safety. This matter was given careful consideration by the various agencies concerned with the establishment of safe practices on the Aqueduct project before tunnel driving was started. Of chief concern were the quantities of toxic or objectionable materials that would be discharged into the tunnel air by the exhaust of the locomotives and the volume of ventilating air that would be required to dilute these exhaust gas products to concentrations permissible in the atmosphere of working places."

Jan 1, 1947

By Jayant Khambekar

In a typical mining operation, run-of-mine (ROM) ore is crushed and screened to achieve a desired particle size distribution and then fed to processing equipment for further refining. For an operation to be profit-able, the ore handling system from the mine face to final product loadout must be reliable. However, the handling system components do not always perform as expected and production problems related to material flow occur. These problems include flow stoppages, limited live storage capacities, uncontrollable flow, segregation, spillage and dust emissions. These result in lost production, excessive maintenance, safety and environmental issues, and even structural failures, in some cases. Flow patterns Flow problems and their solutions can be best understood by first learning how bulk solids flow. As bulk solids discharge by gravity from a storage system, primarily two types of flow patterns can develop: funnel flow and mass flow. Figure 1 shows a schematic of these two flow patterns. In funnel flow, only a portion of the material is in motion during discharge, which flows toward the outlet through a channel that forms within the stagnant material. Funnel flow occurs when a hopper is not sufficiently steep and smooth to ensure flow along the walls or when the outlet is not fully effective. In mass flow, all of the material is in motion whenever any is discharged ? there is no stagnant material. Mass flow occurs when the hopper is sufficiently steep and smooth to ensure flow along the hopper walls. Shallow valleys are not permitted and the outlet must be fully effective. A third type of flow pattern, called expanded flow, can develop when a mass flow hopper (or hoppers) is placed beneath a funnel flow hopper or bin. The mass flow hopper is designed to activate a sufficiently large flow channel in the funnel flow hopper to avoid flow problems due to a rathole. The flow pattern in which a bulk solid discharges from a storage system strongly influences the flow problems that may occur in that facility.

Jan 1, 2009

By S C. Dominy

Various styles of gold mineralisation pose problems during sampling because of their complex gold grade distribution and presence of coarse gold. Effective sampling and sample preparation forms the basis of resource estimates. The design of a sampling and assaying protocol must be based on a thorough understanding of the mineralisation in question, which should include consideration of gold particle size and mass distribution. The proportion of coarse gold within samples has a profound effect on the requirements for sample preparation and assaying. Choice of preparation procedure and assay type is of critical importance if sampling errors are to be minimised. Traditional fire assays, using small charge sizes, often understate assays gained from large charge sizes and techniques such as screen fire assay and LeachWELL. Proper application of the Theory of Sampling reduces errors during collection, preparation and assaying. A quality control/quality assurance program must be implemented and critically assessed. A case study from the Ballarat mine is presented, which is characterised by substantial quantities of coarse-gold hosted in quartz veins. Diamond core drilling is the key input into resource delineation. A number of different sampling and assay options have been trialled over the recent project history. The current sampling protocol utilises whole drill core, using LeachWELL assays after logging and photography.CITATION:Dominy, S C, 2017. Sampling coarse gold-bearing mineralisation – developing effective protocols and a case study from the Ballarat mine, Australia, in Proceedings Eighth World Conference on Sampling and Blending , pp 71–84 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By Xinzhi Du

Coal strength is essential to analyze the stability of excavation in coal. It is well known that the strength of coal tested in the laboratory is size-dependent, and different size specimens will produce different strength. Many researchers have studied the uniaxial compressive strength of coal and developed a number of empirical formulae to describe the strength variation with specimen size. According to a comprehensive data base that includes most of the laboratory testing results in the last century in U.S. and South Africa, the size effect and shape effect were reviewed and analyzed. The results show that different groups of coal specimens have different size effect on the compressive strength. The critical size for the size effect from the data analysis is about 40 in. The shape (W/H) of the specimens has a large effect on the compressive strength. The pillar strength formulae obtained from the data regression have a larger strength than all other existing formulae. Most pillar strength formulae have their own place in coal pillar design field. In order to analyze the difference of those formulae, twelve design formulae have been selected to compare using the Pittsburgh coal seam. The intention is not to determine the preferred formulae, but only to compare them, and see how do the W/H ratio, width, length, angle, cross-section area and effective width affect different pillar strength formulae?

Jan 1, 2008

A new lead refinery with a capacity of 230,000 tons per year commenced operation at Port Pirie in October, 1959. This plant superseded the refinery which had operated from 1933 with the advent of the continuous lead refining process. The incorporation of new equipment following local metallurgical developments, together with the overseas demand for lead of extremely low antimony content createddifficulties in operating the original plant. The new refinery project was undertaken to cover this disability and to gain the full advantage of the new processes.Desilverising and softening are carried out in units identical in size to those used previously. Metallic zinc is recovered from the entire output of desilverised bullion by vacuum distillation. Final refining is carried out by batch treatment with caustic soda yielding lead of purity previously unattainable at Port Pirie.These two processes replace continuous dezincing by oxidation, a high temperature process which caused large quantities of lead and antimony to be recirculated. The final stage is a batch process; therefore the product composition can be checked before casting. Individual batches can be adjusted to produce special alloys to consumer's specification.Improved casting equipment allows the quantity production of pigs of good physical characteristics either as 56 lb bars or 2000 lb pigs.This, together with the high purity of the lead, assures the Broken Hill Associated Smelters Pty. Ltd. (RH.A.S.) position in world markets.Automatic control systems are extensively employed, particularly on the vacuum dezincing unit.The anticipated financial benefits have been achieved mainly by a reduction in the tonnage of recirculated materials, a smaller labour force, and reduced maintenance requirements.INTRODUCTIONIn December 1956 a decision was made to build at Port Pirie a lead refinery on a completely new site, and in October 1959 the new refinery was brought into operation. This plant superseded the lead section of the old refinery which...

Jan 1, 1963

By Peter Klaver

Deep tunnels have been used for decades for the temporary storage of large volumes of urban runoff, both storm water and combined sewer overflow (CSO). Tunnels are attractive because they reduce surface disruption and do double duty as storage and conveyance systems, collecting overflows from multiple locations and transporting them for treatment to various facilities. Like any hydraulic system, however, there are dynamic effects that must be fully understood during the design phase so that the final constructed product does not have unintended negative consequences. Preliminary sizing of storage tunnels is typically based on the total volume required. For example, if studies have determined that a volume of 56.8 ML (15 million gal) will provide the intended level of control, then that figure can be used, along with a preliminary idea of the desired tunnel length, to compute the required diameter. Of course, filling a long tube with water from various points along the way is not at all the same as pouring water into a bucket, and these dynamic effects require additional attention from design engineers. The rapid filling of storage tunnels can lead to the formation of bores, which are essentially moving walls of water. An open channel bore can build in height until it reaches the crown of the tunnel, at which point it becomes a pipe-filling bore. Figure 1 depicts both kinds of bores moving upwards in a rapidly filling tunnel. Bores can strike the ends of tun-nels with tremendous force, driving water and entrained air upwards into dropshafts and creating strong pressure surges in portions of the tunnel that are already filled. If the hydraulic surges are high enough to reach grade, they can cause overflows and/or damage structures at the surface. Trapped air pockets can occur through several phenomena, including the reflection of bores off dropshaft structures and the occurrence of ?premature pressurization.? The latter refers to the situation where the inflow to a tunnel is increasing more rapidly than the tunnel can convey it, such that the pipe becomes surcharged at an upstream point while points downstream are still flowing as an open channel. These air pockets are a great nuisance as they migrate toward points in the tunnel where they can rise to the surface, which are often shafts that are already filled with water (Fig. 2). The ?geyersing? that results can be hazardous and costly.

Jan 3, 2010

By G. Bierie

The conveying of bulk materials is prone to problems. These problems can reduce the capacity and efficiency of the plant, and even threaten the health and safety of the workforce. This presentation will look at new conveyor technologies systems, and how, used separately or in combination, they can improve material handling.

Jan 1, 2007

By Huang Kai

By adding the solid oxalate acid powder into the solution of nickel chloride or its ammonia coordinated solution, the uniform compound particles were prepared and the precipitated particles were transferred to the mono-dispersed NiO particles by calcination. In this study, the various experimental conditions were investigated, the characteristics of the corresponding obtained particles were analyzed, and the formation mechanism of the particles was elucidated. It was found that the solid oxalate acid provided the solid-solution interface for the precipitation and induced the nucleation and growth of the product particles.

Jan 1, 2005