Search Documents

By S. J. Ripke

To pelletize fine moist magnetite concentrate, a 40% water slurry must be dewatered to about 10% by filtration, before it can be agglomerated into pellets. Slurry pH, typically ranging from 8 to 11, gives the magnetite particle surface a strong negative charge and thus causes two adverse effects. First, this negative charge attracts calcium and magnesium cations, which strongly retard the effectiveness of the bentonite clay binder added during agglomeration. Second, a repulsive force created by the negative charge functions as a dispersant that reduces filtering production rates. Tests were conducted to remove these cations during filtration, by rinsing the moisture remaining in the filter cake with a small amount of water adjusted to pH 6 with HCl. Laboratory work was also conducted at Michigan Technological University (MTU) and at Cliff’s Mining Services Company (CMSC) to corroborate the plant tests. In some cases HCl caused filter bag blinding, therefore CO2was investigated to reduce pH. The CMSC lab tests showed that using carbon dioxide to reduce slurry pH from 7.6 to 7.0 improved filtering production rates by 11%. Plant-scale filtering rates were improved by 23.7% when carbon dioxide addition reduced the slurry pH from 8.6 to 6.7.

Jan 1, 2004

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. 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 Christopher Newman, Robert Dupuy, David Newman

"The development of a multiple level underground mine is a complex task in which geology, engineering, ground control, and unit operations are integrated into a single mine design. The components are inter-dependent and must function cohesively to ensure a profitable underground mining operation. To optimize reserve recovery, mine planning should begin from the lowest level and progress up. This limits any misjudgments or oversights of a given level affecting the underlying levels and ensures the ability to maximize recovery from each level.Mine planning should start with the exploration and characterization of the geologic setting. Once the reserve geology and quality is well understood, then mine planning can begin with respect to the following:,Orientation of mine works with respect to horizontal stress,,Access to the reserve,,Determination of opening widths,,Selection of back, floor horizons and pillar centers,,Selection of development and secondary mining heights,,Appropriate interburden thicknesses, and,Examine the stability of the multiple level mine through numer¬ical modeling.The multiple level mine design process and decisions are presented through a case history example. The theme is that there is one opportunity to “get it right” as well as many chances to overlook a small aspect within the design that will plague the mine throughout all levels and through the entirety of its operating life.INTRODUCTIONAs surface quarries reach their economic stripping limit and encroach on mineral and/or reserve boundaries, they approach the end of surface mineable reserves. Furthermore, modern urban sprawl has placed previously remote surface quarries within suburban development and neighborhoods, leading to significant increases in noise, dust, and vibration grievances by the community and regulators (Newman, 2017). Many mining operations have begun year-round production of underground reserves to meet growing market demands. This does not permit the typical sequence of stripping overburden in the winter to provide limestone to mine during the construction season. Underground stone mining operations in the United States commonly utilize a room-and-pillar mine layout with drill-and-blast production methodology for the development of the reserve. Within the Midwest and Eastern regions, thick and flat-lying limestone formations lend themselves to the utilization of multiple level mining layouts. While a multiple level mine plan will increase the overall recovery of the reserve, greater overburden depths, multiple level geometry, and the presence of discontinuities all require an emphasis on ground control for the planning and development of a safe and productive multiple level underground stone operation."

Jan 1, 2019

By J. Brune

The need for reliable and adaptable underground mine communications has become a focal point for both the safety and logistics of a mining operation. New mine communication technology aims to connect personnel, equipment, and data together while setting up a network that can be utilized during normal operations and also in an emergency event. The Mine Improvement and New Emergency Response Act of 2006 (also known as the MINER Act) requires mine operators to establish post-accident, two-way communication between underground and surface personnel and electronic tracking for all mine personnel. Communications systems must be designed such that they can survive major mine accidents, including explosions, fires, inundations and ground falls. Typical, wire-bound communication technologies are vulnerable because wires are often destroyed in such accidents. Wireless technologies that work well on the surface, such as cellular telephone networks; have limited applicability underground because the wireless signals do not propagate through rock.

Feb 23, 2014

By S. Nowosad, O. Langefeld, A. Godge

Pumped storage power plants are one of the options to store the fluctuating production of electric energy from renewable sources in a sustainable manner and is able to provide Europe with the opportunity to overcome the effects of climate change. However, due to the extensive land use required when planning the water reservoirs, several projects have been declined after social conflicts raised, even in Germany. Nonetheless, after the flooding and drought periods in northern Germany, the catastrophic floods of July 2021 in south west Germany, the country’s need to decrease its dependency on import of gas and energy supply, and the energy transition goals set for 2030 and 2050, it has become clear that the implementation for water reservoirs must increase in the coming years, whether above ground or underground. Furthermore, not only Germany is interested in the use of underground cavities for water and energy storage, other European countries as Sweden are currently developing studies and solutions to bring this concept soon to reality in Europe. This article introduces the systematic approach for planning and designing large underground cavities for water reservoirs as a sustainable energy transition approach and a climate change response by showcasing the process of selection and results of the “Energy and Water Storage Harz” (EWAZ) research project. Additionally, the results of the evaluation of the effect of implementing the selected underground and surface infrastructure into the current water management system in the region is presented. Finally, the different possibilities evaluated for the underground cavities within the project and the technical challenges involved are be discussed.

Feb 1, 2023

By C. B. Kettering

In the early operations of the Inspiration Consolidated Copper Company, which extended from 1914 to 1926, the ore as mined contained principally sulphide copper minerals, manly chalcocite (Cu2S), This ore was milled in a 20,000-ton concentrator and the copper was recovered as a flotation concentrate which, was smelted at the nearby plant of the I ternational Smelting and Refining Company. In those days no attempt was made torecovercopper from any oxide minerals present. As mining operations progressed it soon became evident that the proportion of oxide minerals present would steadily increase, and. it was realized that some method of treatment would have to be developed whereby copper could' be recovered from both oxide and. sulphide minerals contained in the ore. A research program was instituted and after some years of experimental and, pilot plant work a new hydro-metallurgical process was developed whereby it became possible to extract copper from both the oxide and. sulphide minerals in a single leaching operation. The solvent adopted consisted of a mixture of sulphuric acid and ferric sulphate,' Following dissolution, the dissolved copper would be recovered by electrolysis. Also in the process of electrolyzing, spent solutions of sulphuric acid, H2SO4, and. ferric sulphate, Fe2(SOk)3, would be regeneratede and. somade available for continuous reuse. The process appeared to be a success and the decision was made to build a full-sized leaching plant for the future treatment of I spiration mixed ore. Construction was started and the leaching plant was completed in 1926, With the start of ferric-sulphate leaching the Inspiration Concentrator was shut down and, with the exception of a few short time runs has not operated since that time. The ferric sulphate leaching process served. Inspiration well for some 30 years and during that time won a name for itself as a classic example of hydro-metallurgical treatment of mixed sulphide oxide ores. Originally the plant was designed. to process some 7,500 tons per day of a mixed ore containing about 1,2% copper, of which 60% was present as oxide and. 40% as sulphide, Down through the years various improvements were made for the purpose of increasing plant capacity and as well to change the limiting 'factor of sulphide-oxide ratio, The final result was a leaching capacity of 9,600 tons per day when treating a 1% copper ore with a reversal of the sulphide-oxide ratio to 60% sulphide and 40% oxide.

Jan 1, 1958

By Johan K. Rodenburg

A major bauxite belt was discovered and evaluated from 1969 to 1974 by P. T. Alcoa Minerals of Indonesia in West Kalimantan, Indonesia. The proven reserves of beneficiated bauxite are 800 million tons averaging 38.6% AA1203 and 3.0% RSiO2. Inferred reserves of washed bauxite are in excess of 2 billion tons. The bauxite occurs as capping of low lying hills which were formed during the post Paleogene peneplaination stage. The overburden varies from 0.6 to 3.8 meters and the nodular bauxite horizon from 2.2 to 5.2 meters. The deposits were formed by the in situ weathering of predominantly acidic and basic intrusive rocks.

Jan 1, 1984

By Jr. Koch

Since 1882, world zinc production has increased. In contrast, United States zinc production rose until about 1915, but since then has remained nearly constant, with a slight tendency to decrease. Production from the Tri-State district, the largest early source of zinc in the United States, has gone down steadily; this decline has been balanced by a growth in the rate of other districts. These changes in United States production are due to economic, not geological, factors. Recent exploration has located large mineable ore bodies; additional deposits will undoubtedly be found in the strata-bound carbonate rock and volcanogenic environments. A statistical analysis of the exploration effort in the Middle Tennessee district indicates that new discoveries can be expected there. Thus, the United States is in an early stage of the production cycle for zinc. Of major mining districts in the United States, only the Tri-State is exhausted under current economic conditions; large zinc resources of low-grade material, which would repay mining at higher prices or improved technology, are known to exist in that district.

Jan 1, 1980

By R. A. Pimentel

Complying with reduced dust standards (i.e., less than 2.0 mg/m3) due to quartz levels that exceed 5 percent is presently a critical problem for many continuous mining sections. Results are presented of research which was performed to determine the factors causing high levels of respirable quartz dust and to identify the major contributors to operator exposure. It was found that the significant sources of quartz dust are the drilling of the roof and the mining of the roof, floor and rock bands. Both the miner and the bolter may be on a reduced standard, but compliance is easiest to achieve on the bolter for which improvements in maintenance and operator practices are usually sufficient. At the miner, the problem is more elusive. Research continues to identify operating and mining practices that contribute to the exposure..

Jan 1, 1985

By James G. Tilton

Throughout the world, sedimentary basins are exploited for many different minerals. Frequently, the extractive methods conflict with one another. A case in point is the proximity of oil and gas operations and the mining of coal. Generally, the interference between the two industries lies in the fact that the reserves over- lie or underlie one another. Mining of coal generally is developed on a rectangular pattern in a horizontal mode while oil and gas drilling is developed on a radial pattern in a vertical mode. Coal mining has exhausted vast acreages in various basins with many of those basins being drilled for oil and gas. Those existing wells create problems by requiring the unrecoverable coal pillars to support the well bore, or to make special provisions in order to mine through an existing well. The system works ... more or less; but there are little or no provisions made for additional drilling unless the vast majority of those new wells are drilled through mined-out sections (gob) of those mines. Many states have rules and regulations governing the drilling of oil and gas wells through gob; but, some companies and some regulatory agencies or personnel have deemed such drilling as a hazard to the mining operations. This paper explores the history, technical standards, and safety aspects of drilling oil and gas wells though the gob of worked-out and active mines. It is the opinion of the author that such drilling can be conducted safely while eliminating the re- quired changes in mine projections and the loss of recoverable coal in the form of well pillars.

Jan 1, 1997

By G. Reed Marchant

The control systems engineer is often faced with the problem of designing tests or experiments where the cost of obtaining information is expensive. This is true in aerospace as well as in process industries. In these situations the details of test design should be carefully evaluated before any test is executed so that the maximum amount of information is obtained for the effort expended. In recent years there has been a steady trend towards increased automation, In the process industries this has resulted in extensive review of process variables and, instrumentation techniques, development of more accurate system mathematical models, and extensive investments in complex control system as well as completely automated plants. When planning and developing these systems, where each measure of a process variable is usually expensive, it behooves the design engineer to give considerable thought to the details of test design before instrumentation is procured and installed so that the maximum amount of information can be obtained for the expense incurred.

Jan 1, 1968

By Glenn H. Damon

Concern about environmental pollution goes back many centuries, but until recently most efforts to control it have been perfunctory and spasmodic, aimed largely at coal smoke and other visible pollutants. Air pollution is to a large degree a byproduct of our economic development, and scientific knowledge of the causes and character of such pollution is more extensive than the technology to handle the waste byproducts of our industrial civilization. The removal of all constituents foreign to the air from the effluents produced by an industrialized society is obviously impractical at this time. There is widespread difference of opinion regarding acceptable ambient air concentration levels for the Various pollutants produced by combustion processes, but there is basic agreement that the pollution of the atmosphere must be controlled and eventually reduced. The magnitude of the air pollution problem has been increasing rapidly because our expanding economy calls for an ever-increasing consumption of energy, and fossil fuels are a principal source of energy. For example, the consumption of electricity has been increasing at an average annual rate of approximately 8 percent over the last 10 or 1.5 years. Table 1 shows the estimated emission of the principal pollutants into the atmosphere in 1966. The approximately 90 million automobiles, trucks, and buses on American highways contribute the largest proportion of pollutants to the atmosphere, but that fact does not alter the growing problems of the coal industry. You will note that sulfur oxides, particulates, and nitrogen oxides are all products of the combustion of coal. Of these air contaminants, sulfur oxides are now receiving major emphasis in terms of research to develop effective means for control, Table 2 shows that the combustion of coal produces approximately 60 percent of the sulfur oxides discharged to the atmosphere. While the utilization of coal is the principal source of particulate matter, this is not considered as serious a problem as it was in the early part of the century because of technological developments that have produced sound methods for the removal of particulates from waste gas streams.

Jan 1, 1968

By T. W. Camm

One function of the U.S. Bureau of Mines is assessing potential economic impacts of federal land withdrawal policies. This often requires performing economic ana1ysls for an area with limited geologic information available. Input to the economic decision process relies heavily on estimates of mine and mill costs for the potential resources in the area being considered. A methodology for performing these cost estimates was needed to address this situation.

Jan 1, 1992

By R. N. Edwards

The Magnetometsic Resistivity (MMR) method is based on the measurement of the low-level, low-frequency magnetic fields associated with non-inductive current flow in the earth. The traditional resistivity method maps the electrical properties of the earth by measuring the electric field caused by galvanic current flow between a pair of current electrodes. The MMR method differs from it in that the potential electrodes are replaced by a sensitive coil or magnetometer and a component of the magnetic field due to the current flow is recorded. The presence of an inhomogeneity redistributes the current flow which results in a perturbation of the electric field and, usually, of the magnetic field. The electric field immediately above a relatively conductive inhomogeneity must, by Ohm's Law, be smaller than that expected for a uniform earth. The current density in this region is also reduced but the current density within the inhomogeneity itself is enhanced so that the horizontal component of the magnetic field measured above the inhomogeneity is usually larger than that expected for a uniform earth. A method of interpretation using the magnetic anomaly was patented by Jakoskyl in 1933 but it met with little success at that time. Part of the problem was undoubtedly with the instrumentation, and only recently have robust instruments of sufficient sensitivity been developed2 and field data of good quality obtained. There are many common configurations of the potential and current electrodes in the resistivity method. Similarly, in the MMR method one or both current electrodes may be moved with the magnetometer, either horizontally or vertically ( in a bore-hole), or the current electrodes may be maintained in fixed positions and the magnetometer alone moved. The MMR anomaly is defined as the difference between the

Jan 1, 1975

By Lawson. Heather

"The purpose of this study is to explore how the geochemical and petrographic components of coal may impact its physical properties, as well as how these components correlate with a history of reportable dynamic failure in coal mines. Dynamic failure events, also termed bumps, bounces, or bursts, are the explosive failures of rock in a mining environment. These events occur suddenly and often with no warning, resulting in worker injury up to and including fatality in greater than 60% of MSHA reportable cases. A database of variables was compiled using publicly available datasets, which included compositional geographic, strength, and Hardgrove Grindability Index (HGI) data (ACARP, 1998). Results indicate that bumping coals are less mature, lower in carbon, higher in oxygen, softer, and less well cleated than coals that do not bump. High liptinite content was found to correlate with higher average UCS values. However, no clear, direct correlation between UCS and dynamic failure status was observed. The findings of this study establish that differences exist between coals that have experienced reportable dynamic failure accidents versus those that have not. These differences are inherent to the coal itself, independent of mining-induced risk factors. Results further illuminate how compositional attributes of coal influence physical properties and begin to clarify potential links between geochemistry and dynamic failure status. Only through the better understanding of risk can more effective mitigating strategies be enacted.INTRODUCTIONDynamic failure events, also termed bumps, bounces, or bursts, are the sudden failures of rock in a mining or quarrying environment. Failure occurs when the rock’s critical bearing capacity has been exceeded and the rock fails energetically through the outward expulsion of rubblized material (Peng, 2008). These events occur suddenly and often with no warning, resulting in worker injury up to and including fatality in greater than 60% of reported cases through the Mine Safety and Health Administration (MSHA). Much research has been devoted to the prevention of these events. The effects of overburden depth and stiffness, mine design, mining practices, and in situ stresses are well documented (Agapito and Goodrich, 2000; Brauner, 1994; Campoli and Kertis, 1987; Holland and Thomas, 1954; Iannacchione and Zelanko, 1995; Lawson et al., 2016b; Mark, 2016; Newman, 2002; Peng, 2008; Whyatt, 2008). Despite these significant advancements in coal mine ground control, however, events continue to occur. Proactive risk mitigation remains an important research area. This is particularly true in underground coal settings, where the rockmass is layered, lithologically diverse, and does not exhibit consistent material properties across deposits.Many conditions have been associated with the occurrence of dynamic failure phenomena, including:"

Jan 1, 2019

By D. M. S. Bhatia

The intimate association of iron formation and massive sulfide deposits has been documented by many investigators (McAllister, 1960; Hutchinson, 1972). In a classic example of such an association four distinct facies (oxide, carbonate, silicate, and sulfide) were identified in an Algoma type iron formation occurring in Paleozoic rocks, but exhibiting physical features (banding) and chemical composition (SiO2 + A1203 + Fe2O3) typical of Precambrian iron formations. The geochemical variation of the iron formation was studied by analyzing 62 samples for Si, Al, Fe, P, S, and CO2. Following a model proposed by James (1954), the geochemical and mineralogical variation of the iron formation can be used as an excellent tool for the exploration of massive sulfide deposits.

Jan 1, 1981

By Richard J. Goff

Technical Support, one of several major organizational units in the Mine Safety and Health Administration, provides technical assistance to the mining community in all areas of health and safety. One of its many areas of expertise is noise control. Depending upon the needs of the operator or inspector, the services provided can range from locating major noise sources to actually building noise controls. Over the years a vast amount of knowledge has been obtained as to what will work and what will not. DESIGN GOALS While many noise controls have been developed for mining equipment and operations, the most acceptable (ergo successful) have achieved the following design goals: - a noise level reduction of at least 5 decibels; - minimum interference with production; - inexpensive to install; and - effective in reducing low frequency noise.

Jan 1, 1984

By Gordon T. Clark, Stephen H. Gleaton

This paper discusses the conceptual design of cut-and-cover tunnels currently being considered as one of the replacement options for the earthquake damaged, elevated double-deck highway and seawall built in downtown Seattle 50 years ago. The 4.8 km (3 mile) long, 6-lane improvement consists of 1.6 km (1 mile) of at-grade roadway with aerial interchanges, 1.6 km (1 mile) of large two-level cut-and-cover tunnels along the Elliott Bay waterfront, and retrofit of the 50-year old, 1.6 km (1 mile)long Battery Street tunnel and north transition to grade. Construction of deep cut-and-cover tunnels, in complex glacial geology overlain by hydraulically placed fill immediately adjacent the existing sea wall, will require extensive use of concrete diaphragm walls, ground improvement and dewatering. The potential liquefaction and lateral spreading of the fill materials in this active seismic region pose significant design challenges and risk.

Jan 1, 2003

By Robert A. Pimentel

Dust is still a major problem in increasing production from longwall faces. Over the last decade, significant improvements have been made in the development of techniques for reducing dust exposure on conventional and continuous sections. But virtually no improvements have been made in dust control on longwall sections. It is true, that there are many more continuous mining sections than longwall sections in the United States and that the number of workers overexposed on continuous miner sections is much larger than the number on longwall sections. However, the problem on continuous miner sections appears much easier to solve and, in fact, we believe that the techniques are available to get virtually all continuous miner sections in compliance. The problems on longwall sections are much more elusive. Also, the number of longwall sections in the United States is expected to increase during the 1980's. Thus, dust control on longwall sections remains a formidable and important problem. Companies operating longwall sections with a dust problem are faced with the tasks of having to quantify the various dust sources, of selecting proper techniques to reduce the problem, of implementing the techniques and of evaluating their effectiveness.

Jan 1, 1983