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By Huiqin Yao, Dongmei Liu

The study investigated the potential use of low activity circulating fluidized bed combustion (CFBC) ash and phosphate tailings for the production of a filling material based on the cement. The phosphate tailings were used as aggregate and consolidated by cement and CFBC ash. The results showed that the bleeding rate and fluidity of all mixtures decreased with the increasing the amount of CFBC ash. The fluidity of filling slurry is highly related to the experimental factors such as the content of sulfur solid ash, B/A ratio, and mass concentration. The replacement of CFBC ash ranging from 20 to 40% led to a significant decrease in setting time and an obvious increase in compressive strength, but the above effect was obviously weakened when reducing the mass concentration and B/A ratio. The hydrated calcium silicate gel and ettringite generated from the hydration of cement and CFBC ash were the main sources of strength for the filling materials. When the recommended proportion was 1/6 binder/phosphorus tailings ratio, 76% solid content, and 40% CFBC ash replacement, the filling material still met demands on working and mechanical properties; at the same time, the utilization of CFBC ash and phosphorus tailings was maximized.

Oct 11, 2021

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

By Richard Klimpel

The laboratory ball mill grinding of coal/water slurries is described for three coals. Emphasis is placed on the measurement of specific rates of breakage for various operating conditions. Corresponding rheological information is also presented based on data collected using a rotational viscometer. A rheological explanation of the influence of various slurry fluidity conditions on the specific rates of breakage is presented. This rheological approach has proved useful In both the identification of suitable chemicals for increasing breakage rates in coal/mineral slurry grinding and in the plant scale implementation of dense slurry grinding systems.

Jan 1, 1982

By J. Bartrum

Kidston Gold Mines is a 14 000 tonnes per day rated operation located 280 kilometers west of Townsville in Queensland. The principle shareholder is Placer Development Limited. Kidston's orebody consists of 44.2 million tonnes graded at 1.79 g/t gold and 2.22 g/t silver. Production commenced in January, 1985, and despite a number of control, mechanical and electrical problems, each month has seen a steady improvement in plant performance to a current level of over ninety percent rated capacity.

Jan 1, 1985

By J. Scheepers, P. Smith, G. (Yunfei) Qiao

High pressure acid leach (HPAL) and pressure oxidation (POx) or pressure leaching extraction processes occur in autoclave vessels operating at elevated temperature and pressure, acidic conditions with abrasive mineral slurries. The harsh process conditions require specialized severe service metal seated ball valves to support operation of the vessels. Over several decades thermally sprayed titanium dioxide (TiO2) and chrome oxide (Cr2O3) coatings have been applied to extend the service life of the ball valves and other high wear critical components. Variability in the coating application quality control and severe process conditions can result in spalling, coating failure and premature failure of the component resulting is decreased autoclave circuit availability. In 2012 MOGAS, together with BRENCO, initiated research and development for ML-381, metallurgically bonded coating. This paper includes the historical development of severe service ball valve coatings, success of the trials and increasing industry adoption of the ML-381 coating for ball valves and other critical autoclave circuit components.

Mar 2, 2022

By Charlotte Abena Benyarku, Albert Buabeng, Eric Stemn

The abstract highlights the increasing use of mobile equipment in mining and its contribution to accidents. The research analyzes injury narratives from Ghanaian surface gold mines to understand the involvement of mobile mining equipment in injuries and explore the use of injury narrative data as a human factors tool. The study identified priority human factor issues, such as operating mobile mining equipment, part removal/installation, and the operator's cabin. The use of Sankey diagrams for multivariable analysis effectively identified specific operator-centered issues that warrant further investigation for improved safety interventions.

Mar 29, 2022

By Reinhard Gertl, Soroush Dabiri, Juan-Carlos de Rueda

The Tunnel of Guillermo Gaviria Echeverri, spanning 6.05 miles, will be Latin America’s longest road tunnel, is currently under construction in Colombia’s Antioquia Department with a single bidirectional tube connected to a parallel rescue tube through multiple cross-passages. The study faces challenges in implementing the prescriptive semitransversal ventilation system due to design restrictions. Different ventilation concepts are eplored to nd the most suitable system for regular operation and re scenarios. A quantitative ris assessment evaluates each alternative system and identies the longitudinal ventilation system, accompanied by ris mitigation measures, as the safest choice, since it surpasses the prescribed semitransversal ventilation concept.

Jun 23, 2024

By Z. Scopa, E. Tarshizi, R. Setterlind, L. Frost, R. Livernois

"THE MINES OF THE FUTURE The mines of the future present a host of challenges, which may appear exciting or daunting depending on one’s perspective. Whether some sectors of the public recognize it or not, the demand for raw resources is not going away any time soon. In fact, it is rising as global population grows, urbanizes and attempts to steadily increase quality of life. Yes, at the same time that much of the highly developed world is calling for greener goods, reduced consumption, and cleaner production, in other areas there are cries for clean water and sanitation, consistent energy supply, access to health care and education, personal security, and support for basic human rights. The balancing act for sustainable development of our global society is indeed precarious, and the mining community is necessarily a key player. Fortunately, many industry members have accepted this role and the responsibility to provide leadership and a solid foundation for progress. Looking ahead, we need new generations of leaders, many of whom will be mine engineers, which are ready to tackle all sorts of complex problems. There are tremendous needs just for technological innovations. Increasingly tough deposits will require that we continue to expand scale toward “super” pits and “deep” underground mining fully develop unconventional recovery techniques like in-situ leaching and gasification or deep-sea extraction, and seriously consider off-earth endeavors. Such work will take entirely autonomous equipment; novel separations, processing and recycling methods; and systems that can withstand extreme physical conditions – just to name a few. It will also take a level of systems integration never-before seen in our field, complete with big data issues, sophisticated analytics and modeling efforts, and cyber-security challenges. Moreover, increasingly complex environmental problems will require creative solutions. Addressing issues like pollution control across multiple media, emerging contaminants, optimal management of wastes, selective mining, and shared use of resources between mine operations and surrounding communities and ecosystems are among top priorities. Really, a complete paradigm shift must occur, such that our focus is on overall improvement of environmental conditions, rather than minimization of impacts. A similar shift will be required in the social realm. How can we make miners safer and healthier on-site and off? How can we contribute to communities such that they are better off, now and long-term, for having a mine next door? How can we help transform artisanal mining practices to also contribute to sustainable development? How can our work be a factor in increasing economic and political stability? How can we improve the public understanding of raw resources and the need for mining enterprises?"

Jan 1, 2017

By David J. Dunn

Mill liner design is an important factor in grinding. Testing and selection of the optimum liner profile for a given set of mill operating conditions can improve mill capacity, liner life, and liner wear rate At a time when mill avilability is at a premium, production costs are going up, and lead time for mill liner castings is a year or more, the mill liner that grinds best, lasts longest, and costs least is a necessity for economic mill operation. In testing four mill liner profiles for 13' x 12' overflow ball mills, Climax found that an improved design increased mill tonnage by 3 tons per hour while reducing finish grind by 1.7% + 100 mesh, reduced liner wear rate, and almost doubled liner life.

Jan 1, 1976

In parallel work, the cyanide/silver impregnated activated carbon system was studied for the purpose of developing an alternate cyanide removal system. It was found that free cyanide can be reduced from 20 ppm to below 10 ppb with a fixed bed of silver impregnated activated carbon, since such cyanide removal might be applicable to gold mill effluents, the investigation was extended to the cyanide/gold impregnated activated carbon (GIAC) system. Batch tests were conducted varying the gold content of activated carbon, carbon/CN ratio, stirring speed, pH of the initial solution, and the reaction temperature. The adsorption isotherm of cyanide/gold impregnated activated carbon system was also studied. The results of these batch tests show that the behaviour of the cyanide/GIAC system is very similar to the cyanide/silver impregnated activated carbon system variation of the gold content of the impregnated activated carbon has some influence on the cyanide adsorption rate. The latter is mainly increased, however, by increasing the GIAC/CN ratio. The activation energy was determined to be 3.12 kca1/mole (13.08 kj/mole) and the Au(CN)2 saturation at 194 µ M/g NORIT ROX O.B. The experimental results of reaction temperature and stirring speed show that the adsorption of free cyanide on such activated carbon is controlled by pore diffusion inside the activated carbon particle or by surface reaction. The adsorption isotherm follows the linear model and it is favourable for the cyanide/gold impregnated activated carbon system.

Jan 1, 1994

By D. J. Miller

Environmental considerations are extremely important in planning and carrying out mergers, acquisitions and real estate transfers. It is not inconceivable that potential or actual environmental liabilities could exceed the targeted company's net worth or the book value of the real estate of interest. It is therefore essential that an environmental due diligence investigation (DDI) be performed to quantify environmental liabilities before sales, mergers or acquisitions. This paper will discuss general procedures used in environmental due diligence investigations. The emphasis will be placed on mergers and acquisitions. It should be pointed out that the procedures discussed in this paper are general and must be modified to fit each particular merger or acquisition under consideration.

Jan 1, 1988

By Mark Colwell

This paper summarizes the results of a research project whose goal was to provide the Australian coal industry with a longwall installation roadway (faceroad) design methodology that could be utilized by suitably qualified colliery personnel. This goal was achieved in 2012 and the design methodology (and software package) is referred to as Analysis and Design of Faceroad Roof Support (ADFRS). The intended benefits to underground operations, in the provision of this information and resource, are a safer and more productive workplace.

By J. R. Hunter

The present is rooted in the past. This is particularly true in the case of mining operations. Coal mining in the United Kingdom is considered an old Industry comprising today 246 Coal Mines many of which have worked coal reserves in their locality for over 100 years. More than half the current producing mines lie in the Yorkshire and Midlands coalfields. They are in the oldest age group and produce 70% of the Industry's output. Some 50% of the remaining U.K. workable reserves amounting to approximately 98,000 million tons are still available to these regions. Fig. 1 Over the past two decades a gradual erosion of demand for coal in the U.K. has virtually halved the Industry's capacity. The number of Mines has reduced by 53% during the past 10 years. Productivity has increased by some 42% mainly through improvements in the central coalfields which has enabled costs to remain broadly competitive with oil.

Jan 1, 1976

By C. R. Pelley

This paper is intended to describe the utilization of Western subbituminous coal as used in a utility-sized steam generator. It compares this coal's characteristics with those of a typical Midwestern and Eastern coal as a base and reviews the various design considerations when blends of these coals are used. The effects of blending various low-sulfur Western coals with Midwestern or Eastern coals to achieve a predetermined sulfur dioxide emission and the resulting alteration in the coal characteristics as they apply to utilization are also reviewed. The blending of coals as one means of complying with sulfur dioxide regulations will take on increasing importance as the various deadlines for compliance with new and existing regulations approach. We must first consider the availability of these low-sulfur coals; and insofar as the Eastern low-sulfur coals have been mined for many years, we have focused our attention on the availability of the coal reserves west of the Mississippi River in the United States, as this is the area to which many people are turning in order to meet this requirement.

Jan 1, 1976

Not quite a year ago, during a speech to a group of mining professionals in Washington, DC, the subject centered around the long-range importance of conducting research projects and how much that research needs to specifically apply to health and safety matters in our industry. The point was made about the critical need to work together with government, private industry, labor organizations and academia speaking with a unified voice as we all march into the future together. The fundamental benefits of competitive research were mentioned --to improve our quality of life, to develop our energy resources, to achieve a safe and healthy environment and to ensure long-term economic growth. Very importantly, emphasis was given to the natural link that makes my agency, the Mine Safety and Health Administration, and the National Institute for Occupational Safety and Health --NIOSH --the beneficiaries of each other's findings. Unquestionably, there are lines of separation. The main responsibility of the agency I represent, MSHA, is enforcement of the nation's mine safety and health laws. But we also have an additional responsibility and that is to coordinate and give priority to research in a never-ending hunt for answers.

Jan 1, 1999

By S. S. SHINDE, P. C. JIKAR, N. B. DHOKEY

Mill scale is an oxide waste product of the steel mills, which contains around 70% iron and other allied impurities. In the present context, a dynamic prototype counter current reactor (CCR) has been used for experimentation and simulation of particle bed by using discrete element method (DEM). Mill scale was pulverized to ASTM mesh range 140 (106 μm)/ + 270 (53 μm), and then it was oxidized in CCR to make single oxide Fe2O3 phase by maintaining required thermodynamic conditions such as pure oxygen at 1100 °C. Then this oxidized powder was subjected to reduction reaction in CCR having gas mixture ( H2:N2) ratio of 1:4 at 875 ± 5 °C for filling degree (fd) and reactor revolution (ω) ranging from 5.38 to 16.14% and 2 to 5 rpm, respectively. A creeping fluid flow condition (Re ˂ 1) and natural heat convection (Gr/Re2 ˃˃ 1) has been maintained while undergoing solid–gas reaction. Besides particle bed behavior has been quantified by Froude number (Fr) for the optimum operating window. The simulation was validated by the experimental results of reactor reaction product by X-ray diffraction (XRD) and scanning electron microscope (SEM) images. Prevailing heat transfer mechanism and reduction reaction mechanism has been established for solid–gas counter current conditions.

Nov 22, 2021

By R. A. Haney

The Mine Safety and Health Administration (MSHA) has conducted studies both in coal and noncoal mines to evaluate methods for sampling and separating diesel particulates from mineral dust aerosols. The agency is investigating size separation techniques to distinguish between diesel particulate and respirable coal mine dust. Additionally, ashing techniques have been used to distinguish diesel particulate from mineral dust in metal and nonmetal mines. As part of these studies, personal exposures to diesel particulate for various mining occupations have been measured. This paper describes the measurement techniques and summarizes the exposure levels for various underground mining operations.

Jan 1, 1990

By M. Brändström, R. Dube, J. Moyo, T. Perkins, G. Bermudez, L. Bartsch, C. Smith, R. Sorensen

The Kennecott Copperton concentrator is currently the bottleneck for the Kennecott operation and several projects have been initiated to increase throughput. This increase in grinding circuit throughput has resulted in a coarser grind size which has impacted flotation circuit recovery. Metso Outotec 300m3 forced air tank flotation cells are currently utilized in the rougher flotation circuit at the Copperton concentrator. Higher overall recoveries have been observed on the newer Outotec tank cells compared to the original 85m3 self-aspirated flotation cells they replaced. However, coarse particle flotation response on these large, forced air cells did not show encouraging results when compared to smaller previously installed cells. This coarse recovery loss has been attributed to the longer froth transport duration and transport distance on large cells (100m3 and larger). Cell manufacturers addressed the risks of additional coarse particle losses in large cells by installing concentric circumferential launders and crowders (also called center launders). These are designed to reduce froth transport time and distance in the last cells in rougher stages where low residual floatable minerals causes a lack of froth mobility. The center launders also increase froth crowding, which also helps to increase froth transport velocity and increases copper and molybdenum recoveries. A trial set of the center launder retrofits were installed on the last three tank cells in one of the parallel rougher flotation rows at Copperton. The launder retrofits were installed at the end of October 2020 and monitored until March 2021. This six-month trial showed statistically significant improvements in copper and molybdenum flotation recoveries through the rougher circuit.

Mar 2, 2022

By Kendrick C. Hardcastle

The practice of transporting an ore or matrix from a pit area to the plant process area by means of a hydraulic pipeline has long been used by the mining industry. The industries which have classically used hydraulic transportation of ore to the plant include the phosphate mining industry, the heavy minerals mining industry, the clay mining industry, and the sand mining industry. As the advantages of this method become better known throughout the mining industry as a whole, and as techniques and expertise improve, its use will undoubtedly spread. Its use is presently being contemplated in iron mining diatomaceous earth mining, and several industries where massive removal of overburden is a predicate to economical mining. The widely recognized advantages of hydraulic transport at ion of ore from the pit area to the mines are: 1) Its relatively low initial capital costs. 2) Its speed of relocation at the mine site. 3) The washing and scrubbing action given to the ore by its hydraulic passage into the pit pump and the subsequent trip through booster pumps down the pipeline to the plant.

Jan 1, 1969

By C. C. Hatch

As part of a general project to simulate a concentrator, the Brenda Mines Limited secondary crushing plant, located near Peachland, B. C., was sampled during the summer and winter of 1975 to develop a digital crushing plant simulator specific to the Brenda operation. The purpose of this simulator was to study the influence of manipulable process variables on important responses and to permit study of alternative circuit configurations if desired. This paper describes the simulation methodology employed and presents the results of a computer study of the secondary crushing plant (1).

Jan 1, 1979