Search Documents

By Michael Schaffer

The paper point out how APC (Advanced Process Control) can be implemented in a stepwise fashion, where each step demonstrates a return and builds towards the overall achievable benefit. Initial efforts focus upon areas that demonstrate the highest potential for quick payback. By attacking small, contained scope, the APC solution is manageable from both a commercial and technical perspective. While this approach results in a slower implementation with correspondingly delayed payback, it provides tangible benefit and addressees the fiscal reality of many operations.

Sep 12, 2005

By Natesa I. Jayaraman

A field study was conducted by the Bureau of Mines to determine the feasibility and effectiveness of a secondary ventilation system retrofitted onto an Eickhoff EDW 340L double-drum shearer as a technique for controlling respirable dust generated during a longwall mining operation. An airflow duct was formed by enclosing the bottom of the undercarriage with steel plate and cutting air channels through the ends of the undercarriage frame. Air intakes were provided behind each cutting drum and at several locations along the undercarriage. Grills were installed at the intakes to prevent the broken coal from entering the ducting. A dust collector consisting of 5,000-ft3/min fan, water sprays, and a minicyclone panel was installed on the shearer at the tailgate end. Field results indicated that the secondary ventilation system reduced respirable dust more than 60% along the face. Reduction was less near the intake airway and when secondary dust sources occurred.

Jan 1, 1977

By Donald F. MacDonald

This report aims to discuss, from the viewpoint of the mining geologist, the bearing of topographic and geologic conditions on cer- tain problems that arose in the construction of the Panama Canal. T+ is published by the Bureau of Mines as a contribution to engineer- ing liters ure because it presents information that shows how geology and topography must be considered by the mining engineer in plan- ning excavations and in removing loose material and solid rock in the safest and most efficient manner. The printing of this bulletin has been approved by the governor of the Panama Canal, as it was impracticable for the Panama Canal to give this information to the general public in any of its publications. The "sword cut" of Goethals and his men did not sever the Isth- mian barrier; it merely clove the hills to a depth of 40 feet above sea level. This cut and the great areas of low valleys at both ends of it have been covered with fresh water to the 85-foot level. This high-level lake held by dams at either end, the 85-foot locks, by which ships enter it, and the dredged approaches from the two oceans constitute the Panama Canal. In the preparation of accurate estimates concerning the cost of large excavations information regarding the geologic conditions, as obtained by a study of natural features, is necessary. Drill holes and test pits will furnish supplementary geologic information, but without a gen- eral knowledge of the geologic conditions it will not be possible for the constructing engineer to answer such questions as the following: (1) What rock units will be encountered in the excavation and in what proportion? (2) What will be the cost of drilling each for blasting (3) How far apart and how deep must the drill holes be to efficiently break the rock of each to the proper size-not too fine nor yet too coarse? In this connection jointing, fissuring, bedding, toughness, and other physical characteristics must be considered (4) How steep will the slopes of the excavation stand, and to what extent will they wash and trench on exposure to the atmosphere? (5) What proportion of the material to be excavated is of such physical character that it may be utilized in any other part of the project, such as in concrete construction, road making, wharves, breakwaters, riprap work, etc.

Jan 1, 1915

By Robert L. Lappi

Eight interburden handling concepts are developed for multiple seam area mine stripping operations in central and western United States. They are based on data gathered and analyzed during field surveys, literature reviews and visits to state regulatory agencies in five states. It is concluded that improvement of reclamation practices through selective interburden handling techniques is possible at lower operating costs than currently incurred. Specific multiple seam mining systems are discussed in this report.

Jan 1, 1980

By R. A. Cummings

Certain roof shales in coal mines deteriorate upon exposure to the atmosphere, causing difficulties in the mining operations and adding to the cost. This report presents the results of both field investigations, in a West Virginia mine, and laboratory studies on the effects of atmospheric moisture on roof shales. Based on these observations, a conceptual procedure is presented on how shale deterioration might be predicted during exploration, and guidelines are given as to how air tempering or conditioning chambers may be designed to reduce moisture effects. Recommendations for further studies are included. An annotated bibliography of the literature constitutes the second volume.

Jan 1, 1981

By M. W. Robotham, H Wang

removal efficiency is analysed from a stochastic

Apr 1, 1995

By Phil Keele

Canadian Natural ??Business Approach Efficiency and Execution ?Drive to be the low cost producer ?Focus on exploitation ?Augment exploitation with strategic acquisitions ?Maintain Discipline and Strength while Delivering on the Defined Plan ?Maintain flexibility and control allocation of capital ?Strive for balance (asset portfolio) ?Maintain financial strength

May 1, 2010

By P Stoker

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Mining and exploration properties have a unique set of technical risks. Privately-owned companies considering investing in the resources sector can optimise their investment decisions by adopting a systematic technical assessment of acquisition assets, similar to the approach commonly adopted by public financial institutions and publicly-listed companies.Technical due diligence provides a process to identify key geological, mining, geotechnical, metallurgical, environmental and social risks and opportunities and determine the most likely business case and valuation of assets. Technical due diligence is commonly carried out in parallel with legal, commercial and financial due diligence, often involving the acquirer, to maximise the understanding of the investment.There are significant advantages in investors conducting a comprehensive technical due diligence, which typically involves site visits and project assessment to international standards by an independent, multidisciplinary team of experts. The outcomes provide the opportunity for the investor to make early, informed decisions and to understand and manage risks.Technical due diligence may be carried out at several stages: when considering and weighing up a number of investment options, prior to and during a transaction or immediately post-transaction. In the first stage, the outcomes will inform the choice of investment and, more particularly, whether there are any fundamental flaws in the projects being considered. In the second stage, due diligence outcomes can inform the level of investment and approach to risk management and planning. In the third stage, risks and opportunities can be investigated in more detail, allowing the investor to consider the best options to reduce risk and maximise the benefit of the investment.This paper presents a summary of the technical due diligence assessment process, its benefits to investors, common risks in mining and exploration projects known to cause mining asset write-downs and principal technical due diligence approaches.CITATION:Keogh, A, Stoker, P and Thomas, M, 2015. Benefits of due diligence in private equity mining investments – maximising value and unearthing common risks , in Proceedings PACRIM 2015 Congress, pp 115–126 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By A. A. Cochran

The purpose of this Bureau of Mines research was to investigate the theoretical and practical aspects of using ionizing radiation to promote chemical reactions that are of interest to metallurgists, and to carry out a radiation study of a suitable reaction. The effect of 44,000 roentgens per hour of 120,000-volt X-rays on the chlorination of highly pure mixtures of rutile, carbon, and various catalysts at temperatures up to 540° C. is described. At these low temperatures, recoveries were very low; however, in the eight different systems studied, an increase in yield due to X-rays was statistically significant in two instances and was of borderline significance in a third instance. In the other five systems, the differences in yield were not significant. Impurities and added catalysts caused relatively large variations in the yield of TiC14 from the reaction. Although the catalysts employed were reported in the literature as positive catalysts for the reaction, most of them were negative catalysts for the highly pure system studied. With only one exception, each increase in the purity of the charge resulted in a decreased yield of TiCl4. The experimental results indicate that many substances catalyze the reaction studied and suggest that the differences in reactivity of the charge stocks may be due to their various contents of positive and negative catalysts.

Jan 1, 1962

By Hideki Shimando

Periodic weighting and windblast which are caused by the dynamic effects of overburden in a longwall panel significantly affect longwall mining This study describes past experience with wind blast at Miike Colliery, proposes a new loosening system using hydraulic fracturing and moistening, and also discusses strength deterioration in hard-to-collapse roof rocks due to water in order to solve the problems caused by the effects of dynamic roof rocks behavior in a longwall face

Jan 1, 1998

By E. Pribonic

Failure of a mine material hoist can cause injuries, fatalities and significant infrastructure damage, along with an associated loss of production. Principal causes of hoist accidents are overwind and underwind. Past and present means of arresting hoisting equipment are marginally effective and utilize destructive systems that are not reusable following an arrest. The use of permanent magnet eddy current arrestor technology is proposed; the history and fundamental science of the technology are presented, followed by real world examples and calculations of performance for failsafe, friction-free, instantly reusable eddy current arrestors as applied to stopping a 30-ton ore skip traveling at 16 metres per second. A comparison of existing arrestor types with the eddy current arrestor is included and limitations of the ECA are also discussed.

Jan 1, 2008

By Maurice C. Fuerstenau

The kinetics of leaching galena with ferric chloride and ferric nitrate have been examined as a function of ferric concentration, salt concentration, temperature and particle size. Diffusivity of ferric complex ions was also established as a function of ferric chloride concentration and temperature. In the presence of 3 M NaCl, leaching rate is controlled by product layer diffusion when ferric chloride is added as oxidant. With NaCl concentrations less than 3 mole/liter rate decreases with decreased NaCl concentration, and, thus, rate is apparently not controlled by product layer diffusion. It is suggested that rate is controlled by lead chloride solubility at the reaction interface under these conditions. When ferric nitrate is added as oxidant, leaching rate is limited by chemical reaction control. An electrochemical model is presented. Activation energies are 8.1 and 11.3 kcal/mol in the ferric chloride and ferric nitrate systems, respectively.

Jan 1, 1984

By Richard S. Watt

The Bureau of Mines is often called upon to analyze the demand for various minerals and fuels and to make projections of the future demand. Because minerals and fuels are raw materials and because the demand for raw materials [pends] on the demand for finished goods, these projections are usually [conned] with derived demand rather than final demand. In order to obtain quick [d] reasonably accurate analyses of the demand for mineral commodities, the [reau] developed a method and has used it successfully (31).4 To illustrate the [thod], this report presents a full analysis of the demand for a mineral commodity with enough general theory to permit application of the method to any mineral. Sodium chloride (common table salt) was chosen as the subject of the analysis because the demand for it is less complicated5 and permits a simple application and clear presentation of the method.

Jan 1, 1962

Once and for all, the debate on the exponent in Gy's formula is pushed to its limit. It is explained why an exponent of 2.5, obtained when using a square root of nominal size d to adapt the value of a calculated liberation factor to a different comminution size, will rarely be encountered in practice, if no arbitrary decisions are made.

Mar 1, 2010

By G. L. Smith

This paper introduces and defines the concept of a linkage between long-term planning parameters (?global assumptions?) and possible future world views as conceived in scenario planning. Scenario planning, the tool that is used to arrive at plausible future worldviews, is described in the context of the platinum industry. The interpretation of the scenarios into long-term planning parameters is made, followed by an illustration of how the long-term planning process has been adapted at Anglo Platinum to include the notion of uncertainty.

Jan 1, 2008

By William A. Hustrulid

An overall summary and the individual reports of eight workshops to determine research and development needs in western mining ore presented. Problem areas are identified, and recommendations regarding priorities, funding sources, and prime movers are made. The objective of this contract was to identify research and development needs for advancing mining technology as well as health and safety measures for western U.S. Surface and underground mining. This was accomplished by convening a series of workshops where problems could be thrashed out by producers of trona, uranium, open pit copper, underground salt (from the Midwest and New York), underground metal and nonmetal, etc. In addition to problems, future priorities, funding, and the desicion as to who should be the prime mover on R & D were discussed.

Jan 1, 1976

?General Facts:Barrick?sFirst Mine in Peru Production started in November 1998 ?The Facilities:Open Pit, Primary and Secondary Crusher Valley Fill Heap Leach PadMerrill Crowe PlantRefinery Environmental Facts: High Rainfall - Average Annual Precipitation of 1,200 mm (47 inches) Rainfall Events: Common 20mm daily events High Altitude Site - Elevations range from 3900 to 4250m. Steep topography - Terrain ranges from 3:1 slopes up to cliffs. Water Issues: Sediment Control - Open Pit PAG Encapsulation - Waste Dump Stormwater control - Leach Pad Erosion Control Techniques ? Offsite impacts mitigation Social Issues: 11 communities surrounding the property Town of Huaraz

May 1, 2003

By Michael D. McGill

The effect of fragmentation size distribution as it relates to front end loader productivity was evaluated by comparing loader cycle times to fragmentation size of the shot rock. At Gold Mine in Southern Utah, a gold deposit containing both limestone and sandstone formations were blasted in the same shot.

Jan 1, 1994

By Witold M. Pytel

A simplified, three-dimensional, time-dependent, mechanistic model of the overburden-coal seam-floor interaction has been developed and validated at two Illinois coal mines. The model based on the thin plate theory can involve any complex layout of mine workings, time-dependent sequence of extraction and, rheological properties of immediate floor strata. The model output data consist of spatially distributed surface subsidence and its slope and curvature, as well as load acting on pillars in one or more panels. A comparison of calculated and monitored surface subsidence or in-mine convergence measurements has proven the model's effectiveness for surface subsidence and load transfer prediction.

Jan 1, 1992

By C. Siyasiya

One of the problems that is occasionally encountered during the continuous casting of DIN 1.4003 stainless steel (hereafter referred to as 1.4003) is the side bulging effect, a problem that is generally prevalent in ferritic stainless steels. This occurs because the unconstrained narrow sides of the solidification shell are not able to withstand the ferrostatic pressure once the strand has emerged from the mould. Coupled with side bulging, there is strand width variation at high temperatures, i.e. when the steel is in the ferrite-austenite dual phase region. Both of these dimensional changes to the slab profile create some processing problems in subsequent hot rolling operations when unacceptable width variations are encountered. The strength of the solidification shell and its ability to withstand the ferrostatic pressure during continuous casting is dependent on its thickness and phase composition when exiting from the mould up to a few metres downstream. From the study of the high temperature metallurgical behaviour of this steel, it was observed that a thicker solidification shell when exiting from the mould and a higher austenite volume fraction in the steel would be favourable for the reduction of the side bulging effect during continuous casting. It was also found that as long as the d-ferrite to austenite phase ratio keeps fluctuating due to variations in chemical composition and process control in the dual phase region from cast to cast, the strand width variation problem would probably persist. The remedy to this effect lies in more strict chemical composition and process control during continuous casting of this steel. The hot ductility experiments revealed that 1.4003 exhibits good hot ductility in the strand straightening temperature range with a minimum of 75 per cent reduction in area and this was attributed to the high volume fraction of ferrite (0.2 to 0.4) in the steel. This would provide a remedy to side bulging by increasing the secondary cooling rate of the strand in order to form a thicker solidification shell without necessarily risking transverse cracking and other surface defects during unbending. Keywords: side wall bulging, resistance bending moment, applied bending moment, ferrostatic pressure.

Jan 1, 2005