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By Jeffrey S. Walker

Abandoned underground mine openings are susceptible to collapse because of the mining methods used, the character of the overburden, and the typically large, wide entries with minimal roof support. The final effect of the collapse of the underground workings is surface subsidence. To reduce the probability of subsidence, methods to backfill the mine void with various types of materials have been developed. This U.S. Bureau of Mines report describes the available technologies for subsidence abatement and discusses their operation and application. The basis of these abatement methods is the replacement of the mined material with mine waste. Backfilling of mine voids is the most common method of stabilization used to abate subsidence and protect surface structures. Hydraulic flushing and grouting, using remote methods from single or multiple boreholes, are the most often-used methods for the placement of backfill material. Other subsidence abatement techniques are available and may be more appropriate under different conditions. These other techniques include pneumatic stowing, either by in-mine or remote methods, and various point support methods that do not completely fill the mine void and are used for the protection of small areas of the land surface and surface structures.

Jan 1, 1993

By W. Y. Gao

Diaojuntai Concentrator adopts a process of low intensity and high intensity magnetic separation and anionic reverse flotation, with all the concentrate from magnetic separation being treated by re-verse flotation to obtain a qualified final concentrate. The high reagent cost and energy consumption of the reverse flotation have led to a high concentrate cost. The test research on reducing the feed to the reverse flotation was therefore carried out. Based on the study of the properties of the ore sample, the concentrate of low intensity magnetic separation was screened at 0.076 mm and the undersize fraction was concentrated by concentrator with gravity and magnetic field. The results show that a qualified concentrate can be obtained at various rising current rate, pulsating current and power-on style, with the operation rate over 85%. The extraction of some part of qualified concentrate from the concentrate of low intensity magnetic separation by magnetic separation can reduce the feed to the reverse flotation by about 35% so as to reduce the production cost of concentrate.

Jan 1, 2014

By J. B. Gayle

Many investigators have reported studies of size distributions for particulate solids ; usually , these have involved the fitting of size distribution data to a particular mathematical function . Such studies are of unquestioned value and have contributed much worthwhile information regarding the breakage mechanisms for a variety of brittle materials . In connection with a Bureau of Mines study of the size distribution of coke , which has been subjected to the standard American Society for Testing Materials (ASTM) tumbler test , attention was focused on the relation between the 1 -inch tumbler index (usually considered to be indicative of the ability of coke to resist degradation by impact ) and the 1 /4 - inch tumbler index ( indicative of the ability to resist degradation by abrasion ) . Specifically , it was noted that for certain sets of data the correlation coefficients denoting the relation between these indexes were positive ; for other sets of data , these coefficients were negative . Preliminary consideration of this problem indicated that the usual interpretation placed on correlation coefficients was erroneous in this particular instance because the variables being correlated were necessarily related . The work described in this report was undertaken to clarify the interpretation of results of correlation studies for variables of this type .

Jul 1, 1960

By D. Lascelles, J. A. Finch, E. El-Ammouri

Flotation separation is expected to be related to the degree of dispersion of the pulp. For instance, highly aggregated systems may show reduced selectivity, reduced entrainment and increased flotation rate. In an attempt to test the impact of aggregation on flotation, we have taken advantage of the effect of Mg ions. Using combinations of Mg2+ and pH gave a wide variation in aggregation of several Cu-Zn ores (measured by settling rate) and corresponding flotation response was determined by batch tests. The trials were conducted on-site at Louvicourt and Agnico-Eagle. In a majority of cases a similar trend in aggregation and flotation selectivity (grade at given recovery) was observed. At Louvicourt, improved selectivity with increasing aggregation at pH 10.5 was found. At Agnico-Eagle, an analogous association between aggregation and selectivity was observed at pH 11.5. It is suggested that aggregation influences particle entrainment, the increased effective particle size reducing gangue recovery and hence improving selectivity.

Jan 1, 2004

By R Brown

The Singapore Land Transport Authority Contract C917A is for the design, construction and completion of all outstanding works under the original Contract 917, including taking over the design and construction responsibility for the works carried out by previous contractor. Construction works connect the bored tunnels between the stations at King Albert Park and Sixth Avenue on the Downtown Line two in Singapore.The original contractor became insolvent leaving the works incomplete. On 29 August 2013 McConnell Dowell were awarded the completion contract following a fast-tracked tender process. The completion contract required a quick start and therefore the recruitment of some of the original workforce. A large majority of the original workforce was from Malaysia, Indonesia, China, Philippines, Bangladesh, India and Thailand. In order to ensure that the safety standards were upheld, and that the new workforce embraced a safety culture, a behaviour based safety (BBS) approach was implemented.The BBS approach was implemented to overcome the existing poor cultural safety behaviours, and to ensure that high standards and expectations for safety were implemented. This ensured that the workforce were comfortable in identifying hazards, avoiding shortcuts, and changing poor safety behaviours.This article outlines how a BBS program was delivered on the C917A project, containing defined goals, communication tools, and assessment and feedback models.CITATION:Brown, R, 2014. Behaviour-based safety with a foreign-based workforce, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 65–68 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By P. Tumialán

El presente trabajo señala la modalidad del empleo en la exploración de las estructuras mineralizadas en diversos yacimientos métalicos a través del estudio de las curvas de sus leyes, curvas estructurales, de potencia y las de cocientes metálicos. Es decir, en este tipo de estructuras se puede estudiar un tipo de las curvas señaladas anteriormente. Asimismo, la mejora del análisis de este tipo de curvas depende de la relación con la petrografía de las cajas, tipos de alteración hipógena, supérgene, rumbo y buceamiento de las mismas, minerales opacos, y ganga de la estructura mineralizada, fracturas y fallas de premineralización y de posmineralización.

Nov 20, 1972

By W. D. Madeley

Synthetic minerals were made from pure starting materials and galena samples were doped with the title metals. Microscopic, microprobe and X-ray examination confirmed that the dopeants were in solid solution. Paired flotations in a Hallimond-tube apparatus were performed to determine relative flotation response using Aerofloat 238 promoter. Results of these tests show that silver-doped galena floats more readily than pure galena and that galena doped with bismuth floats less readily than pure mineral to a 95% confidence level. Galena doped with both silver and antimony as AgSbS2 shows no detectable effect. Antimony-doped galena followed the expected trend, but not to 95% confidence. The results are consistent with the theory that flotation by thiol-type anionic collectors is enhanced by p-type semiconduction.

Jan 1, 1978

By D David

Geometallurgy is often a misunderstood and poorly defined concept. The first thing the paper will attempt is to provide a definition of geometallurgy. Ultimately this paper has been written to provide guidance to geologists, mining engineers and processing professionals as to what geometallurgy means in the crucial early phases of a potential mining project between the time of discovery and the time of commencing construction, should this occur. The paper covers the options available for conducting a geometallurgical study of a resource or orebody, appropriate to the level of definition required in the projectÆs development cycle. The paper will then describe how the geometallurgical information generated is subsequently used in calculations, planning and preparation of reports designed to inform and reassure stakeholders, such as the market. Ultimately in a successful project, appropriate options adopted in the development phase will form the basis of an ongoing geometallurgical program that links the major site disciplines for the good of the operation.CITATION:David, D, 2013. Geometallurgical guidelines for miners, geologists and process engineers - discovery to design, in Proceedings The Second AusIMM International Geometallurgy Conference (GeoMet) 2013 , pp 129-132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 29, 2013

By Joseph Grumer

The range of composition of gases synthesized from solid fuels which are exchangeable with natural gas on current gas appliances was evaluated by theoretical principles. These principles consider primarily the flashback, blowoff, and yellow-tipping characteristics of air-entraining burner flames. It was found that complete identity between the synthetic and natural product is not necessary. Gases such as may be obtained by hydrogasification of coal and other solid fuels without the removal of unreacted hydrogen offer advantages in flame characteristics. Between 25 to 37 percent hydrogen can be tolerated in the sendout gas.

Jan 1, 1965

By V. Panayotov, M. Panayotova

"The combined use of semiconductor properties and specific flotation characteristics of minerals under different conditions with external influences ensures a possibility for process control and management. This work presents the relations between the volumetric and surface characteristics of minerals and the minerals' flotation ability (flotability), as well as the possibility for the flotability purposeful change. Results from proprietary laboratory and industrial research are presented showing how controlled impacts on minerals and flotation pulp improve flotation technology. Such an approach reveals prospects for the creation of new technologies for the minerals' beneficiation.INTRODUCTIONThe decrease of the useful components content in the ores, the increasingly complex nature of the raw materials, the increasing energy consumption per the unit of production, and the need to solve the problems related to the environment pollution require solutions different than the existing classical ones. One of the ways to find such solutions is the detailed consideration of the fundamental properties of minerals and, in particular, of minerals having semiconductor properties. The studies of Plaksin et al. (1968), Chanturia and Shafeev (1977), Chanturia and Vigdergauz (2008), Carta et al. (1973), Hoberg and Shneider (1975), Rao et al. (1992) have given an idea of the energy state of the minerals, their flotation ability, and the ways in which this ability can be changed in one or the other direction. The main line in these works is the study and use of the relationship between bulk and flotation properties of minerals. To improve the efficiency of the process, it is also necessary to consider the relationship between the surface properties of the minerals, especially minerals-semiconductors, and their flotation ability.THEORETICAL BACKGROUND IN BRIEFA quantitative estimation of energy changes in a solid phase in the process of flotation may be made by taking in account the changes in the Fermi level. Its position in the forbidden band is an indicator about the direction and the intensity of electron exchange between solid and liquid phases. The Fermi level energy EF enables the estimation of flotability, intensity of needed external impact before flotation, as well as efficiency of the process going on. Quantitative estimation of these processes can be made by means of the flotability coefficient Kf."

Jan 1, 2018

Control of construction projects is the responsibility of the Project Leaders who have the authority to make decisions. Project Controls cost and scheduling systems provide the Leaders with timely information on which to base their decisions.The Client (Owner) will invest up to three per cent of the project cost on Project Controls. To ensure that this investment is effective, the Owner or Manager must have a clear understanding of the information required from the Project controls systems. If appointing a single Managing Contractor, the Owner or Manager must stipulate what is and what is not required from the Project Controls Systems. There are numerous computer programs available for scheduling and cost control and it is important to select systems which best serve the Owner's needs.

Jan 1, 1993

By E. J. Gleim

In the mining of coal the trend is toward more and more mechanization. This increased use of machinery to replace hand labor is assuming many new forms and presents a constantly changing aspect. Safety engineers must be alert if the many electrical problems resulting from these new installations are to be handled safely. Some of these problems present possible electrical hazards that may be overlooked by the safety engineer unless they are called to his attention by one who has made a special study of the conditions. The foregoing is especially true of conveyor systems of mining. The terms "conveyor systems" and "conveyor mining" as used in this paper refer to those systems in which various types of conveyors are employed to transport coal away from the working place. In some mines this means complete elimination of track, cars, and locomotives. In others it means that conveyors take the coal from the working place to a convenient loading point, from which transportation is completed by cars and locomotives.

Jan 1, 1941

By A. M. Cummings

During August 1943, the Bureau of Mines undertook sampling and measuring of the Kennedy zinc tailing pile near Hazel Green, Lafayette County, south-western Wisconsin, as part of a general investigation of this lead-and zinc-producing area at a time when it was extremely important to increase the production of metals for the Nation's War program. The tailing pile was the residue from old jigging plants that treated ore from the Kennedy mine, one of the oldest and. largest mines in the district. Because retreatment of tailing by modern milling methods was proving economically successful at other sites in the southwestern Wisconsin field, the Bureau?s investigation was designed to assist the potential operators in evaluating the feasibility of a retreatment operation at this site. The study involved measurement of the tailing pile and sampling by means of auger to determine the average metal content within the narrowest possible limits. A total of 46 auger holes ranging in depths up to 40 feet and aggregating 886.5 feet of bore were drilled in the tailing pile, and weighted samples from each hole were analyzed and averaged to determine the zinc and iron content of the tailing.

Jan 1, 1949

By Robert Hopler

Of the common causes of the larger mine accidents, such as falls of roof and coal, gas and dust explosions, mine fires, and the misuse of explosives, all of which are often closely related, each must be studied and fought in a manner peculiar to itself. The last mentioned, the misuse of black powder and other explosives, is sometimes considered the least important of these causes of mine accidents; but its importance is much greater than the statistics indicate, for the reason that the misuse of explosives is the true cause of many of the fatal mine fires, gas or dust explosions, and falls of roof that are credited to other causes.

Jan 1, 2012

By Murray Jacobson

Data obtained by the Federal Bureau of Mines on the dust explosion hazard in air are presented for 220 samples of agricultural products. Information is given on ignition temperature of dust clouds and layers, minimum explosive concentration, minimum electrical energy for ignition, explosion pressure and rates of pressure rise, amount of inert dust required to prevent flame propagation, and, in a few instances, the permissible oxygen concentration in an atmosphere to prevent ignition by spark and by heated surface. The effects of particle size and source of sample on explosibility are shown. The relative ignition sensitivity, severity of explosion, and overall explosibility of the materials are characterized by empirical indexes. This report contains Ma obtained by the Bureau in laboratory studies on the explosion hazards of agricultural dusts. Recognition of the dangers will encourage adoption of adequate measures to prevent ignition and explosion during preparation, processing, and utilization of the materials. Agricultural products constitute one of the largest groups of materials used in America. More than 260 million tons of various grains, much of which now exists in dust form, was grown in 1958.6/ Over 600,000 tons of the annual production of 200

Jan 1, 1961

By B Murphy, T Mattsson, R Crosbie, T Maksimainen

"An Outotec e500 TankCell, with 500 m³ of actual flotation volume, was commissioned at the Kevitsa Cu-Ni-PGE concentrator in northern Finland during 2014. This flotation cell was implemented at the head of the existing copper circuit as the first Cu rougher flotation cell. This was the first flotation cell of this size to be run under production conditions by any supplier anywhere in the world.The cell has been in continuous operation since start-up in October 2014 and has provided improvements in metallurgical performance at very low specific power consumption. On average, the cell has recovered 71 per cent of copper contained in the 0.37 per cent Cu flotation feed at a concentrate grade of 17 per cent Cu. The specific power consumption for the cell (excluding blower power) is typically around 0.4 kW/m³.After start-up, the impeller speed and superficial gas velocity were varied and the impact on metallurgical performance measured. In this paper a review of the cell operation at Kevitsa is given. Furthermore, the impact of mixing and gas dispersion on metallurgical performance is presented.Citation:Crosbie, R, Mattsson, T, Murphy, B and Maksimainen, T, 2016. Metallurgical Performance of Outotec's e500 TankCell at the Kevitsa Cu-Ni-PGE Concentrator, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 127–134 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By B. Gorain

"INTRODUCTION The last few decades have seen some remarkable advancement in information technology, but recently various digital technologies have resulted in several synergies to deliver innovation in diverse applications. The mining industry has been relatively slow in adopting these technologies compared to the other industries, but this scenario is changing fast. Keywords: Digital Transformation, Operational Intelligence, Gold Recovery, Mine to Mill integration, Planning and Execution strategy, Theory of Constraints. Challenges Mining companies globally are going through a series of challenges such as declining ore grades with complex metallurgy, increasing depth of ore bodies, high capital and operating costs, lower productivity, shortage of technical resources, significant pressure from stake-holders to deliver, along with growing environmental and corporate social responsibility issues. Improvement in profitability would need significant improvements in operational performance. Consequently, over the last few years, there has been a major focus amongst some mining companies to imbibe Operational Excellence. This has been only possible because of the replacement of a silos based approach by an integrated view of the organization. Such an integrated view is now possible via the evolving digital technologies. Even so, such a transformation calls for a change in culture, which, for most organization is not trivial. Attempts in the past to integrate functions such as through Mine-to-Mill initiatives in the mining industry have demonstrated significant benefits to many operations (McKee, 2013). Still, sustaining these benefits has clearly been a challenge due to manpower turn over and lack of proper systems and structures that integrate information between business functions within an operation and between operations and the corporate.Opportunities The advent of digital technology has opened-up opportunities to integrate inter-departmental information for a unified understanding of, and across, an entire organization. The advances in instrumentation, equipment control systems, supervisory control systems (SCADA/Historian) and industrial networks have helped in the direction of enterprise wide integration. The availability of real time information across an enterprise has given rise to numerous possibilities to improve organization performance. As suggested by Seshan & Gorain (2016), some of the potential opportunities are as follows:"

Jan 1, 2018

By Paul J. Smith, Eudomar A. Silva, Quang D. Tran, J. Milton Brooks

The Dallas Mill Creek Drainage Relief Tunnel is an 8.04 km (5 mile) tunnel that will provide 100-year flood protection for impacted neighborhoods in the east Dallas area. “Big Tex” is a main beam gripper TBM capable of changing diameters in mid-tunnel to excavate 2.83 km (9,290 ft) of 11.45 m (37.58 ft) diameter tunnel and 5.21 km (17,095 LF) of 9.93 m (32.58 ft) diameter tunnel. Construction began in April 2018 and is anticipated to be completed in 2024. This paper will discuss the challenges and lessons learned during assembly and re-assembly, start-up and mining with “Big Tex.”

Jun 13, 2021

By E. S. Burnett

The temperature entropy (T, S) chart? of thermodynamic properties of nitrogen herewith presented is a complete (1949) revision and a considerable extension of similar charts prepared by the author for use of the helium section of the Bureau of Mines about 25 years previously on the basis of inadequate data then obtaining. During the interval since that early effort, much experimentally determined information on nitrogen properties and behavior has been published, which now permits a more nearly accurate layout and more extensive charting of these relations.

Jan 1, 1950

By A R. Bye, T R. Stacey

Anglo PlatinumÆs Potgietersrust Platinums (PPRust) operates three open pits and plans to excavate 90 Mt of rock in 2007. With pit slopes expected to reach a height of 400 m, the geotechnical department has a key role to play. Over the last four years PPRust has successfully implemented new geotechnical strategies and tactics to reduce risk, improve safety and maximise profitability. A large database of core logging, face mapping and rock testing data has been assembled and used for failure analysis, geotechnical zoning and rock mass ratings. The data has also been used for optimising blast designs on a daily basis through the use of a geotechnical block model. This greatly improves blast fragmentation and therefore loading and milling efficiencies. The slope design process involves limit equilibrium analysis, numerical modelling, rock fall analysis and block modelling. Slope management includes comprehensive limit blasting and visual inspections, and state-of-the-art slope monitoring equipment, namely the GroundProbe radar, Riegl lasers and GeoMoS automated prism monitoring. The risk-consequence approach has been used in slope optimisation, where all the slope analyses, operational controls, costs of failure, economic analyses of various slope designs and fault tree analyses are used to determine the ideal slope designs. These activities added over $25 million of value to the operation and also ensured compliance with Anglo AmericanÆs acceptable risk level. The successful mining of the optimised slopes is to due to the greatly improved geotechnical knowledge and slope management. PPRustÆs geotechnical work is used as a benchmark for Anglo American open pit operations. The focus of the paper will be on the value added to the operation by all aspects associated with slope management.

Jan 1, 2007