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By Steve Wiig

In 1987, the Rock Springs, WY district office of the US Bureau of Land Management (BLM) began to develop an automated system to store, maintain and manipulate more than 14,000 drill hole logs contained in the district's office files for various solid leasable minerals. The development of this system was based predominantly on a trial-and-error basis, with many procedural changes incorporated over time. The current Automated Drill Hole Database and Analysis System will continue to evolve with new software developments and increased personal expertise in this field. The mission of the BLM's Branch of Solid Minerals is mandated by a series of federal laws. The most important are The Mineral Leasing Act, the Federal Land Policy and Management Act, the Federal Coal Lease Amendments Act and the Surface Mining Control and Reclamation Act. Several regulations, promulgated from these laws, dictate that BLM must perform certain tasks and functions as part of its specific duties. The regulations that apply to the BLM Solid Minerals program are codified at 43 Code of Federal Regulations (CFR) 3400 for coal, and at 43 CFR 3500 for non-energy solid leasable minerals, such as sodium, phosphate and potash. Specific functions required of the Branch of Solid Minerals necessitates the use of geologic and drill hole data analyses. These functions can be divided into pre-lease and post-lease. Examples of pre-lease functions that normally require some level of drill hole data analyses include:

Jan 1, 1992

Water quality standards for some of the substances likely to be discharged to natural waters by the mining industry are discussed. After briefly examining how uses of water can be affected by discharges, standards for suspended solids and turbidity, pH, and toxic materials are considered. Heavy metals are examined in some detail because of recent public concern regarding their discharge. Caution is given in connection with their analysis at the very low concentrations required for management of natural waters. Finally, the issues of what constitutes a water right concentration compliance breach, and the appropriateness of biological monitoring as a condition on a water right are raised.

Jan 1, 1986

By J. A. Herbst

During the last decade it has been established that conventional flotation control strategies based on classical control theory result in significant increases in grade, recovery, and operating-cost savings. In the current report a description of an advanced model-based control philosophy is presented. The derivation and verification of a simplified flotation model is described. The implementation of a Kalman filter for estimation of unmeasured variables for input to controllers is discussed. Several control strategies using the model-based approach are described, emphasizing the nonlinear nature of the flotation plant. Expected trends in the implementation of such model-based flotation control strategies in the future are discussed.

Jan 1, 1986

By P. Perruzza, R. Grandori, A. De Biase, A. Ciamei, A. Busillo

The Turin metro alluvium soil is mainly made of large boulders, cobbles and gravel , few sand and almost no fines. This grain size curve is out of the range of application for EPB and Slurry TBMs. In order to bore 5 of the total 7,5 kms of Line 1 tunnel, two specially designed Lovat EPB TBMs were utilised in combination with a systematic non structural pre-grouting of a small volume rectangular slab just above the tunnel section. The same pre-grouting was not however applicable for lack of access on surface in some sections of the remaining 2,5 km of tunnel that had to be bored below important buildings/structures, with under ground water pressure up to 1,5 bar, with curves radius of 180 m only. For these more critical sections it was necessary to study and implement a new technical solution and improve the capacity of the TBM to work efficiently in EPB mode even in this unsuitable ground and overall conditions. After months of studies the selected and adopted solution has been to inject inside the cutterhead chamber, in addition to the almost standard foams & polymers additive mixes, a suspension of limestone powders. This with the scope of compensating the lack of fines of the natural ground with rock powders.

Jan 1, 2005

By M R. Stevens

The Kauri Block (Hauraki Hill) andMatawai Valley epithermal vein systems, near Coromandel township, are hosted by hydrothermally altered Miocene andesites and Mesozoic greywackes of the Coromandel VolcanicZone. The hydrological setting of both geothermal systems was probably that of an andesitic volcanic arc. Two types of veins are recognised: 1. Simple veins composed of fine comb quartz, and 2. Complex (breccia) veins composed of vein fragments of sulphide-bearing, chalcedonic silica cemented by saccharoidal and fine comb quartz.   Pyrite, arsenopyrite, marcasite, and gold form the ore minerals. Both deposits historically exploited hypogene and supergene bonanza gold.   At Hauraki Hill, breccia veins up to 7m wide contain abundant fragments of recrystallised colloform banded-crustiform textured quartz veins ('Golden Cross' style) and were probably major channels for ascending deep mineralising fluids. Alteration assemblages are zoned with the higher elevations of Hauraki Hill-Bunkers Hill characterised by strong kaolinite alteration whereas deeper levels are dominated by illitic clays.   At Matawai, complex veins and hydrothermal breccias pinch and swell, and inflect, within a total width of veining and alteration that exceeds 50 m. The greywacke host rocks are altered to an assemblage of illitesmectite, quartz, chlorite and pyrite although there are pockets of kaolinite.   The proposed genesis of veins and ores in both deposits invokes episodic rapid mixing (quenching) of hot mineralising reservoir fluids with cool acid condensate waters, whilst acidification and increased fO2 triggered gold deposition. These hydrothermal systems heated up during their later stages and at Matawai visible gold was deposited from a late mesothermal stage. The main conclusion is that the northwest CVZ has excellent potential for large gold deposits (= 30 tonnes contained gold).

Jan 1, 1993

By B Belle

Dust sampling is pivotal in estimating the ‘dose’ of dust exposure and in deriving dose-response curves in epidemiological studies. Over the last half century, gravimetric sampling has been the fundamental means for dust exposure monitoring using recognised respirable size-selective standards. In Australia, a gravimetric sampling technique has been followed since 1983 using the Higgins-Dewell (HD) type cyclones (AS2985). The re-emergence of ‘Black Lung’ or Coal Workers Pneumoconiosis (CWP) in Queensland, Australia has re-kindled the need for better understanding of personal dust monitoring, compliance determination, accuracy, timeliness of sampling results and dust control systems. Reporting dust levels in real time empowers miners and operators to take immediate action to avoid being exposed to excessive airborne dust. Two decades of intensive research in the USA has led to the introduction of gravimetric based continuous personal dust monitors (CPDMs) called PDM3700 as compliance tools. The new real-time mass based sensor is a continuous mass based dust monitor using the Tapered Element Oscillating Microbalance (TEOM) principle and is regarded as significantly superior to the current gravimetric sampling methodology.Recently the overall respirable dust standard in USA coalmines has been reduced from the historic 2.0 to 1.5 mg/m3. This paper provides the results of a comparative pairwise study of an existing gravimetric sampler and the PDM3700 carried out in 3 different Australian underground mines. The field results consistently suggest that there is a significant ‘measurement bias’ between the current gravimetric HD sampler and the PDM3700 monitor operated using a similar HD type cyclone. The results show that the currently used cyclone measurements are approximately 59 per cent higher than the ‘auditable’ PDM3700 monitor data at the current compliance limit of 3 mg/m3. Based on a review of the extensive data collected, the differences can in part be attributed to the aerosol size selectivity of the samplers with the current gravimetric sampler used in mines, collecting more larger sized particles (D90 of 15 µm). This finding has significant consequences for historic exposure results and their use in medical surveillance programs, as well as the current approach to non-compliance determination.CITATION:Belle, B, 2017. Pairwise evaluation of PDM3700 and traditional gravimetric sampler for personal dust exposure assessment, in Proceedings Australian Mine Vent Conference 2017, pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By W. Barnett

The Limpopo Metamorphic Belt is a complex geological terrane with at least three major deformational events. Tectonically juxtaposed lithology, open to isoclinal folding, crosscutting and re-activated shear zones and metamorphic gneisses and schists make pit slope design and maintenance a risky business. Venetia diamond mine?s Cut 3 is planned to reach 360 m by 2011. The difficult rockmass created problems in the original pit and a new more comprehensive slope design was necessary. Nearly 9 km of geotechnical drilling were undertaken to produce a new geological model and provide geotechnical information near the final Cut 3 face. All existing data from the pit were brought together into a database. SRK Consulting were brought into the project to audit the process and provide most of the manpower for the data analysis. Existing failures were back-analysed and the geotechnical domains identified. Analyses of only the southern domains are discussed in this paper. Geotechnical engineers can design slopes at any angle, but it is up to the managers at the mine to decide what risk they are willing to accept in a slope design. Once the issue of risk was discussed and settled in respect of the consequences of failure, each of the main geotechnical domains were analysed to produce a slope design at5% probability of failure with 15% above the first ramp. A risk assessment of the design was then undertaken to determine what risk the design placed on the equipment, personnel and the profitability of the overall mining operation. The risk assessment indicated minimal risk to the operation. One of the main assumptions of the final design is that the pit slopes will be dewatered. A project was immediately put in place to determine a groundwater model for the mine and to thereby determine the best dewatering procedure. However, it should be obvious that it is practically impossible to prevent benches from getting briefly saturated with water during storm conditions. It was therefore necessary to look specifically at supporting the crests of the ramps in the problematic southern domains to guard against the possibility of crest failure during heavy rains. The data available were re-analysed toward this objective. Spiles were recommended as the most cost-effective support system, and a probabilistic approach was used in the design. The final design has a 5% probability of failure, and the analyses indicate a strong sensitivity of the required spile spacing to the strength of the reinforcement material that will eventually be used. The pit slope parameters derived as per the discussion in this paper have just begun to be implemented at Venetia Mine.

Jan 1, 2001

By A. W. Khair

Laboratory studies indicate that the specimen size influences the compressive strength of coal significantly. In the past, the diameter/height ratio of coal and rock specimens with different geometry and its influence on failure characteristics was discussed (Khair, 1993; Khair, 1994; Khair and Xu, 1994). In the current attempt, tests are designed and carried out under uniaxial condition in the laboratory to investigate the influence of specimen size. Cubical specimens of coal with edge dimension ranging from 5 cm (2 in.) through 20 cm (8 in.) were prepared according to the standards and tested uniaxially. Results show that compressive strength of coal is dependent on specimen size until certain level and later the change in specimen size would not yield significant change in compressive strength. Cubical specimens were chosen for testing because they are not only in close resemblance to underground pillars, but they are also the most stable shape under loading. The failure characteristics of these specimens were analyzed and their applicability to pillar design aspects in coal mines is studied. A detailed analysis of the physical and mechanical properties of the tested coal seam is also presented.

Jan 1, 1996

By William R. Barton

Anthracite has been mined from the Narragansett Basin of Rode Island and Massachusetts sporadically, and with limited success, for more than 170 years. Beginning in 1974, interest in the coal of the Basin was renewed because of increasing prices and supply uncertainties involving petroleum products. During 1974-77 the Bureau of Mines analyzed 28 samples of Basin coals and conducted washing tests on 20 of them. Results, reported herein, indicate that the coals are low-sulfur, moderate- to high-ash anthracites and semianthracites, suitable for physical preparation to a product generally containing less than 10 percent ash. Additional exploration, sampling and testing will be required to permit appraisal of the potential value of the Narragansett Basin coal resources.

Jan 1, 1977

By Bowang Xiao

Recently more and more attentions are paid to high pressure hydrogen quenching (HPHQ) for its advantages such as environmental friendliness, low distortion, etc, compared to oil and water quenching. In HPHQ process, heat transfer coefficient (HTC) usually varies from part surface to surface because of the intense variation of gas velocity around the part. This article studies the effect of HTC distribution on part distortion after HPHQ and shows that finite element simulations considering HTC distribution predict different distortion from these without considering HTC distribution. It is also pointed out in this article that HTC distribution can be optimized by adjusting part orientation and HPHQ condition so that part distortion is minimized.

Jan 1, 2010

Floor heave events in underground mining often happen suddenly and cause risk to workers and equipment. Reducing the risk of floor heave must be addressed in mining layout design. To improve that design one must understand the significant parameters that are correlated to the occurrence of floor heave. To accomplish that goal, researchers from the National Institute for Occupational Safety and Health (NIOSH) completed a numerical study using FLAC3D, taking advantage of its strain softening and ubiquitous joint capabilities to better simulate the floor heave and caving mechanisms involved at an actual mine site.

Jan 7, 2020

By Bruce I. Thomas

[THIS PAPER, tine of a series on placer ml n in iii Alaska, describes mining methods and gives unit costs at operations where hydraulic and mechanical excavation equipment is used with nonfloating washing plants. The mining methods described were developed during the last 30 years to copy with conditions peculiar to arctic and subarctic regions arid are now used by a large segment of the placer mining industry in Alaska. The operations described have been classified if m ii into three main categories: Those having sluices at a bedrock level, those having sluices above bedrock and those having mobile nonfloating washing plants (dryland dredges). Diesel-powered bulldozers and draglines convey or clevate gold-bearing gravel to the sluices, remove tailings, and strip waste gravel and other overburden. Diesel-powered centrifugal pumps supply water foe sluicing and hydraulic stripping. Detailed descriptions and unit cost arc presented for 14 operations to illustrate the numerous arrangements udder the first 2 categories.]

Jan 1, 1959

By A. Cabañas

"In this paper, geostatistical techniques are applied to forecast the annual copper price in the short and medium terms (from one to five years ahead). These techniques allow the incorporation of monthly and multivariate information in the analysis and provide more accurate results than traditional approaches, especially as far as the one-year forecast is concerned.A second advantage of geostatistics stems from its ability to assess the uncertainty associated with the unknown future prices, thanks to estimation variances or confidence intervals, depending on the technique used. Such an assessment has a crucial importance in decision-making, from both macroeconomic and microeconomic points of view. IntroductionThe copper price traded in the London Metal Exchange is a relevant parameter for defining macroeconomic policies of producing countries like Chile. It is also a key factor for the mining companies, since fluctuations in the sell price affect the expected financial flows. Due to the amount of money involved in decision-making, it is necessary to have accurate forecasts of the future copper prices and to quantify the uncertainty associated with such prices.This paper focuses on the annual copper price estimation in the short and medium terms, i.e., from one to five years into the future. Henceforth, the word “estimation” will be used as a synonym of “forecast,” according to the geostatistical jargon (Matheron, 1989).Two main approaches, based either on statistics or econometrics, are currently used to forecast commodity prices, but both of them are not very accurate when applied to copper. First, the main methods are briefly reviewed, then the geostatistical formalism will be presented. So far, the latter approach hardly has been used to estimate commodity prices, although it may reconcile both statistics and econometrics via (1) the use of a stochastic approach and (2) the handling of ancillary variables related to the copper market. Another advantage of geostatistical techniques is the ability not only to forecast the copper price, but also to measure the uncertainty associated with it."

Jan 1, 2004

By A. Krishnan

Keywords: Tantalum extraction, SOM Technology, inert anode, membrane stability The Solid Oxide Oxygen Ion conducting Membrane (SOM) technology offers great potential for environment friendly and energy efficient extraction of high-energy content metals. This work was performed to demonstrate the technical and commercial viability of the technology to produce tantalum metal directly from tantalum oxide and ore concentrates using a solid-oxide, oxygen-ion-conducting membrane (SOM). The process can be used to efficiently produce tantalum metal without expensive pre-processing of raw materials and without harmful by products. The work reported in this paper is: the proof that high purity tantalum metal can be produced, study of the electrochemical behavior of the cell and the method to increase membrane stability.

Jan 1, 2005

By J L. Mauk

Low sulfidation epithermal deposits are important sources of gold and silver, and are considered the extinct analogues of modern geothermal systems. The aerial extents of alteration halos that surround twenty-two epithermal deposits range from 4 to 315 km2, with many less than 60 km2. Deposits with alteration halos <30 km2 typically have well defined limits, whereas deposits with alteration exceeding 30 km2 are commonly complicated by overlapping alteration centres related to adjacent epithermal deposits or other deposit types (i.e. high sulfidation, porphyry). Irrespective of the physical coverage of vein or alteration halos, both large (>60 km2) and small (<20 km2) deposits can contain large amounts of gold and silver. The size ranges for twenty-one analogous liquid-dominated geothermal fields from around the world have a restricted size range of 5 to 60 km2 and irrespective of physical size, commonly have multiple zones of focused fluid upflow. From an exploration perspective the comparison between epithermal deposits and geothermal fields provide the following four important points. 1) Alteration halos surrounding epithermal deposits as well as those for analogous geothermal systems show a range of sizes, although most are less than 60 km2. Therefore, where alteration exceeds 60 km2 multiple vein systems related to several paleogeothermal systems are predicted. 2) Multiple upflow zones are common in geothermal fields of all sizes (5 to 60 km2) and although difficult to demonstrate in epithermal deposits there is a strong possibility of discovering several discrete adjacent mineralised centres. 3) The orientation of veins parallels the principle orientation of the surrounding alteration and where alteration is wider than the vein strike length, this could suggest the occurrence of adjacent veins. 4) The physical size of both veins and alteration zones is not important in relation to amount of contained gold, as both large and small can contain large amounts of gold. These conclusions provide insight into the physical size limits and hydrologic structure of these paleogeothermal systems and highlight the potential for multiple mineralisation centres within a single alteration halo.

Jan 1, 2004

By L Langer, R Simcock, M Davis

Rehabilitation of mining sites helps to achieve the purpose 5(2c) of The Resource Management Act 1991 û æavoiding, remedying, or mitigating any adverse effects of activities on the environmentÆ. The environmental outcomes for recent and current mining operations on the West Coast are variable. There are some exemplary mining operations which are restoring or even improving land use and environmental factors in the region, particularly those operated by the larger mining companies. There are also examples of an exploitative mentality where the environment and land have been severely degraded by mining activities. Technology has been developed to prevent a repetition of the historical destruction of the environment through mining. Failure to rehabilitate mined land is no longer acceptable to the New Zealand public in the 1990s and damages the credibility of the mining industry. Examples of successful mine site rehabilitation to pastoral farming and to production or plantation forestry are illustrated from the alluvial gold mining industry. Planning, sequencing of operations, the utilization of sailor plant growth materials, and aftercare are key factors in successful land rehabilitation to these productive uses. There is also a recent focus on restoring indigenous forests and wetlands at both coal and gold mining sites, particularly for mines on or adjacent to the conservation estate. The results of scientific research and efforts by the industry on techniques for rehabilitating rainforest and pakihi wetland after mining are presented, particularly from the Giles Creek Dunoille Coal Mine. There is a need for further research and trials to apply and extend rehabilitation techniques to other geological and environmental situations, particularly to mines in mountainous areas and to difficult environments like the coal measures ecosystems of the plateaux above Westport.

Jan 1, 1996

By J. P. Sancho, J. M. Duart, J. I. Verdeja, J. O. García

Following a short review of the history of rails used in the transport of passengers and goods, this paper describes the process for rail fabrication, rail structure, and properties, and summarizes the fatigue test curves carried out on rails used today. Also reported is the process for “continuous rail” production using aluminothermic welding via the introduction of weld metal in onsite casting, as a homogeneous melt. Weld characteristics of aluminothermic welding using different preheating procedures—fusion zone, heat-affected zone, microstructure, hardness, slow bend test, and fatigue test resistance (Wöhler curves)—are related to preheating and welding procedures of 700, 900, and 1,100 MPA rail grades. The Locati method is preferred over the staircase method for ascertaining the fatigue limit due to its simplicity. Macrographic and metallographic inspection of broken specimens reveals the reliability of welding techniques and the good metallurgical quality of welds.

Jan 1, 2007

By Gabriel S. Esterhuizen

This paper addresses the need for a method to compare the effectiveness of different support systems when designing ground support in coal mines. At present, support design methods include empirical methods based on observations of past performance of installed support systems, analytical methods where the roof is typically simulated by elastic beams and numerical model analysis. The approach presented in this paper estimates the relative stability of a support design through geotechnical evaluation of the rock mass and numerical model analysis of the interaction between the rock mass and the support system. Models are used first to simulate the design performance at the expected rock conditions. The rock strength is then reduced until collapse is indicated in the model. The stability factor is then calculated as the ratio of the expected rock mass strength to the rock mass strength at the onset of collapse, and is similar to the well-known factor of safety used in engineering practice. The stability factor can be used to assist in developing a final support design by comparing the effectiveness of various support systems and the stability of excavations under various geological and loading conditions. Examples of the method?s application in three different geological settings are presented.

Jan 1, 2012

The exploitation of the underground is currently undergoing a major transformation process. Besides mining, alternative ways of utilization are playing an increasingly important role. These alternative utilizations include the storage of gases, the disposal of radioactive wastes and the implementation of geothermal storage facilities. In addition, more and more mining operations are being shut down, like the German hard coal mining industry in 2018. But the integrity of closed mines must be ensured in the post-mining phase.

Jan 7, 2020

By I. J. Brown

Paper prepared for presentation at Industrial minerals and the environment, held in Leeds, 24-35 September 1990. The need to submit an environmental statement (EIS) has certainly increased the workload of those concerned with both its production and assessment. However, there is now good evidence that the system is enhancing public confidence in the minerals industry in particular and improving relationships between the developer, planning authority and those consulted such as statutory bodies, parish councils, civic societies, nature conservation interests and ramblers

Jan 1, 1991