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By Ping Zhang, Shahram Mozaffari, Andreas Ylmefors

The risk associated with mining induced seismicity and the related rock bursts has become one of the major threats to the safety and sustainability of mining at the Kiirunavaara mine. The causes of mining induced seismicity at the Kiirunavaara mine are very complex and have affected our understanding on the source mechanisms of seismicity and further the mitigation of the seismic risk. Detailed analysis of historical mining induced seismicity at the Kiirunavaara mine was conducted. The focus of this analysis was placed on the classification of large seismic events and the evaluation of the influential factors on the classified seismic events. 145 events with local magnitude larger than 1.5 that occurred between January 1, 2011 and March 31, 2021 were analyzed. For this analysis, seismic events located in the hanging wall were not included, as these have not been observed to cause large damages to the mine itself. It was found that the magnitude of the events had good correlation with the stress change in relation to the production location. The seismic events were classified as mining-front associated, ore-pass associated, mining-front and ore-pass associated and others, according to their hypocenter location. Most of the mining-front associated events, concentrated around the production levels and slightly above and below them, generally correlated with shear cracks, and most of them occurred when the ore flow between two production levels started. The numerical modelling showed that slip of the geological discontinuity, due to unclamping between hanging wall and footwall, could be the major causative mechanisms, which further supports this finding. The ore-pass associated events are located close to the ore passes. Large seismic events located between ore passes have the source mechanism of both fault-slip and non-shear, but events located at the outer side of ore passes were all fault-slip type. By checking with the ore pass scanning data, it was concluded that the most of the events located between ore passes could be pillar bursts. An elastic core concept has been then used to define a critical pillar width. The paper is not intended to be prescriptive but rather to initiate discussion of the possible classification of seismic events at the Kiirunavaara mine and to present new perspectives of the causes of the seismicity for improving the present seismic risk management.

Apr 26, 2022

By John J. Friel

The addition of dolomite to iron ore pellets improves their high-temperature reduction properties primarily by increasing their reducibility and raising their softening temperature. In this study we prepared dolomite-fluxed pellets from three different concentrates; Hibbing, a magnetic taconite, Knob Lake, an earthy hematite; and Carol Lake, a mixture of specular hematite with magnetite. The composition n of the concentrates is given in Table I. The pellets were subjected to standard physical tests and the following reduction tests: low temperature degradation, swelling, softening, and thermogravimetric analysis. Petrographic examination and electron microprobe analysis allowed us to evaluate the effect of composition and firing on the phase assemblage. Further, we were able to interpret the test results in terms of chemistry and microstructure. This approach enabled us to determine which fluxed composition best suited each of the concentrates.

Jan 1, 1980

By J. G. Dunn, A. S. Ibrado, D. J. Hollbach

Gold production is one the most important mineral process­ing industries in Western Australia. The gold is usually found in either weathered oxidised zones, or associated with sulfides. In the latter case, oxidation is achieved by some form of chemical processing, such as roasting or more recently bacterial leaching. In all cases, gold is dissolved out of the oxidised matrix by cyanide solution. Pyrrhotite is an iron sulfide generally represented by the formula Fe1_,S where O x 0.125. Three different structural forms ofpyrrhotite are known to occur naturally, stoichiometric FeS (troilite), hexagonal pyrrhotite Fe1_xS and monoclinic pyrrhotite Fe7S8 [I]. Substitution of iron atoms within the pyrrhotite structure by other ions of similar atomic radius such as nickel, copper, cobalt and manganese is also possible [2], and often observed in natural pyrrhotite samples. Pyrrhotite is abundant in Western Australian sulfide mineral deposits which are commonly associated with gold bearing ores. It is generally believed that pyrrhotite has a detrimental effect on gold recovery from such ores, as it is commonly claimed to decompose in alkaline, aerated cyanide solutions to form iron cyanide complexes, thus consuming free cyanide, and to form sulfur/oxygen containing species such as sulfate, through oxidation of sulfur in pyrrhotite, which thus consumes oxygen. From information gleaned from the literature, claims about the high reactivity of pyrrhotite in cyanide appear to be based on early cyanidation studies performed on gold ore samples which have been poorly characterised, and contained impurities such as pyrite, arsenopyrite and chalcopyrite, which may have also contributed to the levels of species observed in solution [3-5]. In addition, the investigations do not take into account that iron atoms in the pyrrhotite structure may have been partially substituted by other atoms that influence the solubility of pyrrhotite in cyanide solution.

Jan 1, 1995

By F. G. Loper

Simulation as a mathematical technique is not new. However, recent increases in digital computer speeds and the ease of programming with languages such as Fortran have centered a good deal of attention around simulation in the last few years, Many sophistications of the method have been developed during this time. However, the ability to simulate mathematically still hinges on the ability to ignore unimportant details which would complicate the mathematics and make simulation impractical, Thus, with this attitude in mind, it becomes very easy to design a pseudo- simulator which will predict average conditions very well, but can not truly allow a detailed study of the system being simulated. Most simulations fall into this category, along with the case mentioned here. This paper is not intended to be a critical treatise of the simulator used to study a particular mining system. Instead, it will be used to illustrate the aspects of simulator development. The steps in the development of any simulator are described, along with same detail of the phosphate mine simulator itself.

Jan 1, 1966

By Miles T. Stephens, Felipe Calizaya, Jacob O. Kingston

Currently, the Bear Canyon Mine is facing the challenge of excessively high coal and rock temperatures in one of its headings. In Mine No.3, the air temperature at the 6th Right panel reached 36.4ºC and the coal 83.9 ºC. Due to these severe work conditions, the mining plan has been altered by changing the mine direction to avoid the high temperatures. To investigate the problem, drill holes were developed from the entries and the rock temperatures monitored using K-type thermocouples. The measurements confirmed the existence of localized “hot spots” in the mine. This paper presents a summary of ventilation surveys that were conducted in this mine. It includes the results of coal and rock temperature measurements from drill holes, interpretation of results using a heat flow simulator and the identification of hot spot areas. It also includes a summary of methods that were developed to reduce the hazard and control the problem.

Jan 1, 2005

By B. Nyman

A lot of work is in progress to improve copper recovery by leaching-solvent extraction-electrowinning (L-SX-EW). At Outokumpu the focus of attention is on SX equipment development as a result of which a new mixing-settling technology, the Vertical Smooth Flow (VSF) has been introduced. Using helical stirrers in the VSF mixers a more gentle and uniform contacting can be obtained than in the mixing compartments of the low-profile design. The benefits of Outokumpu's new approach are an essential decrease in organic losses and in aqueous in organic entrainments. Separate pumping using a smoothly pre-contacting "Dispersion Overflow Pump" (DOP) is a key feature of the VSF design. The scale-up of this pump as well as the VSF mixers are shown to follow simple mathematical relationships which also have been confirmed by full scale experiments.

Jan 1, 1995

By R. J. Zagrocki

Rekindled public concern about lead toxicity has intensified the awareness of lead-bearing materials in contact with the environment and the human population. Lead's common association with other metals makes the increasingly restrictive lead standards a primary concern for a large number of metal and metal-related industries. In commercial scale demonstration tests with lead-bearing wastes, the HRD Flame Reactor process has a demonstrated ability to separate and recover over 95% of the lead as a recyclable oxide, while rendering the remainder of the material as vitrified, non-leaching, and nonhazardous co-product. Recent Flame Reactor process tests and preliminary cost data for secondary lead soda slag are highlighted.

Jan 1, 1992

By Lawrence E. Mannion

In southwest Wyoming lies buried the world's largest source of natural sodium carbonate, or soda ash. Perhaps a hundred billion tons of trona (sodium sesquicarbonate) are contained in ancient lake beds in the Green River basin'). There the Green River Formation encloses more than 40 extensive beds of trona. At least 25 of these exceed 3 feet (1 meter) in thickness and most of them are more than 300 square miles in extent. Five have been exposed in mines and lie between 800 and 1500 feet below the surface. Others lie at depths of from 400 to 3500 feet. Three companies have underground mines that supply trona to adjacent soda ash plants. These are the FMC Corporation, Allied Chemical Corporation, and Stauffer Chemical Company. A fourth, Texasgulf Corporation, has a mine under development. In 1974, annual soda ash capacity in the Green River area was approximately 4,300,000 tons, which requires the mining of about 7,500,000 tons of trona.

Jan 1, 1975

By Lynton S. Land

Representative collections of recent dolomites, and of samples concentrated by leaching-out of coexisting magnesian calcites, provide grounds for appraisal of the compositions and cation ordering in recent dolomitized sediments. Unit cell volumes for near-stoichiometric compositions exceed those of ordered dolomite and increase as the departures from regular cation order became more pronounced. Infrared absorption maxima of disordered examples occur at perceptibly lower frequencies. Stable isotope ratios indicate that best ordered examples formed in highly saline environments. Present observations are qualitatively reconciled with data from synthetic products described by other authors.

Jan 1, 1972

By Tom F. Deems

The term ball clay is applied to plastic sedimentary clays that have a high content of kaolinite and that possess white firing properties and high green strength (Mitchell and Stentiford, 1973). However, the name ball clay is not derived from any specific property of the clay. Instead, it comes from the original method of production in southwestern England (Scott, 1929). From open pits, the clay was cut into cubes with hand tools. The sides of the cubes were about 220 to 250 mm (9 to 10 in.) and weighed 14 to 16 kg (30 to 35 lb.). The eventual rounding of the corners with handling before sale gave rise to the term ball clay. Ball clays provide the workability and green strength required by the whiteware section of the world's ceramic industry. The main applications are in the sanitaryware, tile and tableware sectors. Each, though, requires particular technical properties in the ball clay component. The clay has to be as white firing as possible for all applications. However, for sanitary-ware, the rheological properties are most important. For tableware, fired whiteness and freedom from specking are the main criteria. Tiles need a reasonable green strength but the clay also needs to be cost-effective. The technical properties of the individual clays in any deposit depend on the clay mineral assemblage. This, in turn, depends on the geological formation of the deposits. Hence, it is the latter that largely determines the market sector for which the clay blends from a particular deposit are suited. Formation of ball clays Ball clays are formed from three main components - kaolinite, micaceous minerals and quartz - while carbonaceous material is also often present. The crystallinity of the kaolinite and mica varies. There are also occasional minor occurrences of feldspar, chlorite, montmorillonite andmixed. layer minerals. Marcasite, siderite and anatase also occur in small amounts. The properties of the clay depend on its mineralogical composition and its particle size distribution, particularly in the lowest size ranges. The original source rocks and the environment of deposition of the clay are the controlling factors. The importance of weathering processes in the formation of ball clays has long been recognized (Bristow, 1968). The diversity of source rocks produces considerable variation in the clay minerals formed. Therefore, each deposit is unique, with time-related variation within it. The greatest development of a weathering mantle takes place in a tropical climatic environment. Plant remains confirm that most ball clay deposits were formed under hot and wet conditions. Sedimentation of the clays had to be in fresh or low salinity water or clay minerals detrimental to whiteware manufacture would have been formed. Fresh water traps for the ball clay, sand and lignite sequences depended -on tectonic features, such as basin development along fault zones or lakes and lagoons on the edge of a large scale embayment. These factors for Devon ball clays were discussed by Vincent (1983). The combination of suitable source rocks, tropical climate, significant fresh water sedimentary environment

Jan 1, 1997

In its April 1991 issue, MINING ENGINEERING published a salary survey form asking for information relating to engineering and management jobs in the minerals industry. 1038 of these forms were filled out and returned, most of them being received in the magazine's offices at SME headquarters before the end of June 1991. An SME volunteer took on the task of tabulating and analyzing data from the forms, but the press of other business interfered with this work, and publication has been delayed until this issue of MINING ENGINEERING. Appreciation is extended to SME members who took the time to fill out and return the salary survey forms, and our apologies go to MINING ENGINEERING'S readers for the delay in publication. Of the total number of forms received, more than 97% were from SME members. The geographic distribution of the respondents closely mirrored that of SME membership as a whole, about 50% being from the Society's Western Region, 19% from the Central Region, and 23% from the Eastern Region. About 8% were from outside the US. Average salaries for each of the four geographic areas ranged between $55,000 and $60,000, with the highest average in Eastern Region (Fig. 1). Respondents were asked to answer a number of questions formulated to determine if there are significant differences in salaries based on the type of organization for which they work. As indicated by Table 1, salary averages at mining companies do not vary markedly with the size of the company: • Large companies, defined as those having more than $1 billion in annual sales, accounted for just over 16% of the returns. Their average salary was $61,840 per year.

Jan 1, 1992

By Harvey Parker

This is part two of an article on the prominent role that the United States and its industry leaders have played on the International Tunnelling and Underground Space Association (ITA), which represents the underground construction and underground space industries worldwide. The U.S. is officially represented in ITA by UCA of SME. (Part one is in T&UC, June 2007, pp 39-42) Tunnel advances in 1960s and 1970s The 1960s and 1970s were active and productive times for the U.S. tunneling industry. During that time, federal programs, sponsored by the Federal Railroad Administration (FRA), the Office of High Speed Ground Transportation (OHSGT) and the Advanced Research Projects Administration (ARPA), stimulated tunnel research and development. Also, the American Society of Civil Engineers (ASCE) and SME collaborated to create the Underground Construction Research Council (UCRC) and the Rapid Excavation and Tunneling Conference (RETC) series.

Jan 1, 2007

By H. Colijn

The ever increasing price of bulk commodities forces buyers and sellers in world markets to take a more careful look at methods for obtain¬ing accurate accounting of commodity trans¬actions in commerce and material utilization in processes. Depending upon the application of a sampling and weighing system or the use intended, inaccuracies can result in an eco¬nomic loss of income or a loss in quality of the process. It inevitably results in a loss of control of ones costs. The accuracy of samp¬ling and weighing systems is today extremely important, as they are recognized to be the key components of the overall management system designed to provide both quantitative and qualitative control. This paper will be confined to the weighing systems only and will deal with various as¬pects of system design, calibration and opera¬tions. Special emphasis will be placed on new developments and requirements in this field.

Jan 1, 1988

By Tom Michaud, Rob Albinger, Ian Turner, Michael Rispin

Data transmission, communication, tracking, and the connection of equipment such as gas detectors, cameras, and collision avoidance systems in today's tunnel industry are critical pieces of the constructor's infrastructure. Reliability, flexibility, redundancy, and cost-effectiveness are key in selecting and implementing inte- grated systems. Both wired and wireless components are used to deliver custom solutions and can involve interconnectivity between backbones. Systems integration is important as industry adopts proven technologies from other industries. Case stud- ies are given showing how tailor-made approaches deliver needed functionality, with varying degrees of com- plexity, in various classifications of environment, in order to meet a project need.

Jun 23, 2024

By G. L. Mowrey

One of the critical parameters of any automated coal mining system is the ability to only cut coal and not the rock / waste surrounding it. To do this the system must be able to detect where the coal-rock/ waste interface is. The U.S. Bureau of Mines is investigating a new approach to vibrational coal interface detection (CID) by utilizing an adaptive signal discrimination (ASD) system to perform feature extraction and classification of complex vibrational signals. Accelerometers, geophones, and piezoelectric films are mounted on mining machines and/or strata and are used to monitor vibrations produced during mining operations. Selected data are digitized and the ASD system is trained on known types of vibrations (e.g., "cutting coal" and "starting to cut roof"). A signal classifier is then generated which can be used to identify unknown waveforms. The ASD system can be retrained if mining conditions change significantly.

Jan 1, 1990

By K. Rajamani, L. B. Hales

Much of the process control effort in the mineral industry uses proportional-integral-derivative controllers that require periodic retuning. Retuning hundreds of controllers typically employed in a single plant is a formidable task for the control engineer. Adaptive controllers offer an alternative to this problem, since they are designed to tune themselves. Four schemes of adaptive control-gain scheduling, model reference adaptive control, self-tuning regulator, and optimal adaptive controllers-are discussed with process examples. The control of a ball mill circuit with a multivariable self-tuning regulator is illustrated. This controller encompasses the advantages of the other three controllers and is applicable for a wide range of process variability.

Jan 1, 1988

By Allegra Yeley, Ted Klemetti, Gamal Rashed, Tim Miller, Nicole Evanek

In 2015, the Subtropolis Mine in Petersburg, OH, experienced a massive ground collapse that continues to grow over time. Horizontal stress effects have affected the roof at this operation in the past and may have played a large role in this collapse. Horizontal stress can impact the roof and floor stability and endanger the health and safety of underground stone miners. Mines experiencing damaging effects from horizontal stress typically find that the principal stress direction is the same throughout the mine and the region. At the Subtropolis Mine the principal horizontal stress direction appears to change as conditions change and differs from the regional horizontal stress, particularly near the collapse or other roof fall areas. The growth over time of this collapse and other roof falls have been captured and analyzed using geologic mapping, 3D LiDAR scanning, numerical modeling and geographic information systems like ArcGIS. Utilizing these tools to better understand sitespecific conditions can be critical to reducing the potential of massive ground collapses in the underground limestone industry.

Feb 1, 2024

By Steve Kral

The Society for Mining, Metallurgy and Exploration’s origins can be traced back to 1871. This was when 22 Pennsylvania coal mining engineers founded the American Institute of Mining Engineers (AIME). The organization’s objective was to “promote the arts and sciences connected with economic production of the useful minerals and metals, and the welfare of those employed in those industries by all lawful means.” Metallurgy and Petroleum were added to the AIME name in 1919 and 1956, respectively. Divisions of AIME were formed throughout the following years in recognition of the increasing trend toward specialization among mineral industry engineers. At the time, SME’s divisions consisted of the Coal Division (1930, now known as the Coal and Energy Division), the Industrial Minerals Division (1935), the Mineral and Metallurgical Processing Division (1948) and the Mining and Exploration Division (1949). The Environmental Division was created in 1997.

Jan 1, 2007

By K. V. S. Sastry, K. D. Lofftus

Mathematical modeling and computer simulation are two valuable quantitative tools that are being effectively applied to mineral process- systems. This paper presents an up-to-date assessment of process modeling and simulation, identifies a number of associated challenges and opportunities and discusses in detail sane of the aspects of applying the current state-the art modeling and computational tools.

Jan 1, 1989

By Neil Jagger, Ian Arbuthnot, Mitchell Gordon

Ultra high density underflow is required in many thickener applications and in mineral processing is typically required for tailings to improve the thickened slurry rheology for either tailings dam development or for paste backfill applications. The improved liquid-solid separation resulting from the production ofultra high density underflow has both environmental and process benefits in the gold industry. Additional cyanide is recovered in the thickener overflow thus reducing plant cyanide costs and perhaps more significantly, a reduced quantity of cyanide is discharged to the tailings thus reducing either the toxic effect on the environment or the costs of cyanide destruction. Many gold and other mineral processing plants are situated in arid regions where the cost of water is high and the quantity often very restricted. Ultra high density thickened underflow results in increased recycle of tailings process water to the plant. In Countercurrent Decantation circuits, the wash efficiency is very dependent on the degree of liquid-solid separation in each thickener stage and the benefits ofultra high density underflow are either increased efficiency or decreased equipment costs as it may be possible to reduce the number of stages in the circuit.

Jan 1, 1995