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By O. P. Sinha, Biswajit Mishra, A. K. Mandal, Raj Kumar Dishwar, G. S. Mahobia, Ram ji Omar

Most of the mineral deposits found in North-East India remain unexploited due to inadequate knowledge on their status, economic viability, and requisite mining technologies. The aimof this study is to characterize the multimetallic magnetite mineral deposit from the Nagaland area in India. The quality of iron ore was evaluated to establish its suitability as a raw material for iron production. Detailed studies were conducted to establish the composition and properties of the samples. X-ray diffraction (XRD), X-ray fluorescence (XRF), electron probe micro-analyzer (EPMA), and petrographic microscopy techniques were employed in the investigation. Shatter and tumbler test was performed for analyzing the mechanical properties of the ore. XRD studies indicated that magnetite is the major mineral with low amounts of martite, maghemite, and quartz. XRF/EPMA results indicated that magnetite contains 35–65 wt.% of iron and 1–5 wt.% of chromium. It also confirms the presence of Ni and Al up to 1 wt.% and Si up to 6 wt.%. Chromite-rich ore contains up to 30 wt.% Cr and 15–20 wt.% of Fe.

May 10, 2021

By P. R. Dugan

Sulfur removal from high sulfur coal has several objectives including: a) reduction of the atmospheric load that contributes to the problem of acid precipitation; b) reduction of ash, which contributes to decreased energy transfer in boilers, as well as ash disposal; and c) alleviation of the social and economic dislocations related to uneven geographical distribution of sulfur in coal reserves. Cost in relation to the value of refined coal will govern the development of an emerging coal refining industry. Estimation of the premium paid by power companies for coal with a low sulfur content is a good estimate of the value that will be added as the result of refining. Estimates of premiums paid in 1984 are $28.65/t ($26 per st) for reduction of total sulfur from 370 to 1% S and greater than $28.65/t ($26 per st) for removal below 170 sulfur.

Jan 1, 1988

By N. C. Saxena, S. K. Puri, A. K. Pal

The condition-based monitoring system is an important innovation for reducing the downtime of costly, heavy earth- moving machinery (HEMM). Vibration severity measurements were made on the HEMM located at the Gevra Project, the largest coal opencast project in India. Whenever the vibration severity levels exceeded the permissible limits, necessary actions were taken to replace the defective parts of the ma- chine. The systematic vibration monitoring of 120-t (132-st) dumpers, followed by corrective measures led to a substantial increase in component life (8.18% for an 445E Dressor and 28.44% for an MK-30 Unit Rig). The associated costs (including spareparts) were reduced by 21.55% and 25.74%, respectively. Because of the reduced downtime, savings for these two dumpers over the period from March 26 to June 25,1998, were of the order of Rs.26.47 (US$0.649) million.

Jan 1, 2000

By J. H. Hammarstrom, S. M. Fortier, W. C. Day, S. J. Ryker, R. R. Seal

"The United States’ supply of critical minerals has been a concern and a source of potential strategic vulnerabilities for U.S. economic and national security interests for decades (for example, see Strategic and Critical Minerals Stockpiling Act, 1939). More recently, with the rapid increase in the types of materials being used in advanced technologies (Fortier et al. 2018a), and geopolitical events surrounding the supply of rare earth elements (Ting and Seaman, 2013), among other developments, the critical minerals issue has again achieved a high level of visibility within the U.S. government (Executive Order 13817 (2017)).In this paper, the U.S. Geological Survey (USGS) provides an overview of its ongoing focus on critical minerals through the agency’s core competencies in mineral information, mineral resource assessments, geologic and topographic mapping, geophysical surveys and mineral resource research. Aspects of the multifaceted critical minerals issue addressed here include:• Identifying minerals that meet the definition of “critical” provided in Executive Order 13817.• U.S. net import reliance for critical mineral raw materials.• Current status of domestic critical mineral resource assessments.• Current status of topographic and geologic mapping, and geophysical survey coverage of the United States.• The Earth Mapping Resources Initiative (Earth MRI) to support future critical mineral exploration.• Critical mineral potential of waste streams from extractive industries.Identifying minerals as criticalU.S. government agencies and other organizations use a number of existing definitions and criteria to identify a mineral or mineral material as critical, strategic or otherwise important. The executive order defined a “critical mineral” to be “(i) a nonfuel mineral or mineral material essential to the economic and national security of the United States, (ii) the supply chain of which is vulnerable to disruption, and (iii) that serves an essential function in the manufacturing of a product, the absence of which would have significant consequences for our economy and national security.” This definition is broadly consistent with that defined by the National Research Council (NRC, 2008) and may be summarized as “essential in use” and “subject to disruption of supply.” Virtually all of the dozens of critical minerals studies conducted since the 2008 NRC report have used some variation of this same definition (Hayes and McCullough, 2018)."

May 1, 2019

By Richard C. Holmquist

Some of you may be old enough to remember -- as I do -- the early days of World War II. A highly prepared, well-equipped Japanese striking force had moved like lightning across the South Pacific islands and Southeastern Asia. As the invasion force pushed its way down the Malaysian Peninsula, Singapore stood serene and beautiful, protected by its natural moat of water, busy as ever with its commercial pursuits. One can see its captains of trade and industry now, sitting com¬fortably on the veranda of the "Singapore Country Club", sipping scotch between cricket games, convinced that the weary, logistically extended Japanese force couldn't possibly cross over to their island which had been so secure for a hundred' years or more. No need to remind you what happened. The brave men in their ships at sea and in the gun emplacements ashore were hopelessly out-gunned and out-maneuvered.

Jan 1, 1979

By H. Colijn

Vibratory or oscillatory conveyors can be found in all types of industry, handling virtually any granular bulk material, often at elevated temperatures. These conveyors can be combined with other process functions, such as screening, cooling, drying and dewatering, while conveying. Although construction and installation is relatively simple, the engineering and design analysis of the vibratory mechanics is fairly complex. This paper will discuss the basic types of vibratory conveyors and the analysis of the material movement along the carrying trough.

Jan 1, 1985

By Ray A. Rothrock

The in situ mining of uranium is the process whereby chemical lixiviant is injected by means of wells into, and flowed through, an ore body. The lixiviant reacts with uranium which has been previously oxidized making the uranium soluble. The solution is then brought to the surface by means of producing wells. In situ mining disturbs the ground-water quality in the immediate area. Since ground water is a natural resource used by man, care must be taken not to allow the lixiviant to escape the local mining area. Also, when the ore body is mined out, the area should be restored to as near its original state as is reasonably achievable. The return of ground-water quality to its original state can occur naturally over a long period of time or be enhanced using appropriate technological means.

Jan 1, 1981

The last time Mining Engineering presented an issue with a special focus on Canadian Mining (ME, August 2008 pp. 28 to 40) things were going well. A feature story took a look at Xstrata?s Nickel Rim South Mine in Sudbury and the booming Canadian oil sands were discussed at length. Potash prices were soaring, large diamonds were being found and British Columbia was launching plans to find more workers. How things have changed in six short months. What began as a mortgage crisis grew into a credit crisis, then mutated into a financial crisis, that has taken its toll on the value of bonds, loans, stocks, real estate and commodities. Miners that were flying high on unprecedented commodity prices six months ago have begun scaling back with delays, shut downs and layoffs as they struggle to survive this most recent economic downturn.

Jan 1, 2009

By Yao Dun-Pu

Solution mining, sometimes also refered to as chemical mining or bacterial mining, is an innovative technology which, by making use of proper chemical reagents and taking advantage of bio-chemical action of some micro-organism species, can dissolve effectively most. desirable metallic values from ores and then extract them profitably from the resultant metal-bearing solution by suitable means to form the metal product it is more preferable to the conventional mining methods, not only because of its capability to improve working conditions and minimize environmental problems either underground or on surface, but also for its amenability in particular, to exploit low-grade or submarginal ore bodies, or those deposits which are too deep-seated to be mined out economically. Furthermore, it also provides a potential approach to win metals directly from their ores or ore-deposits in-situ by more simplified methods and at a lower cast than the conventional mining-milling-smelting process would do previously. Hence, in developing countries such as China, it will most, probably become a new mining tool of great promise. (1)

Jan 1, 1981

By R. A. Williams

Surface and electrochemical techniques have been used to describe the surface chemistry of ferrosilicon powders, as a function of pH and electrochemical potential, for conditions typical of operating DHS plants. The practical consequences on the likely corrosion behaviour and associated electro- kinetic particle-particle interactions (which affect stability to sedimentation) in the suspension, are discussed.

Jan 1, 1987

By Jan M. Mutmansky

Simulation is a general term which commonly appears in the technical literature and which can have different meanings to different people. One interesting definition (9)* applicable in an engineering context is the following: "Simulation is the use of a model to study a problem." In most cases, the model referred to in the above definition is a simulation model constructed in a computer language and implemented on a computer in order to solve the problem under consideration. The application of computer simulation models to the study of problems in materials handling and earthmoving has been successful in the past. Generally speaking, this method has been used where the system to be studied has many variables and where the ability to predict the outcome of the system under different sets of conditions is difficult. The prime reason for using such a model is to evaluate the numerous likely ways of operating any particular system without the necessity of actually conducting full-scale field tests. The simulation model presented here is such an application made to the process of tunneling and, in particular, to the process of tunneling with a boring-type tunneling device. At first glance, the process of tunneling may not appear to be particularly complex and susceptible to study by a computer model. However, a close analysis of the tunneling process will reveal that it is rather complicated as a result of limitations placed upon the system by restricted space in the tunnel, geologic variations along the tunnel

Jan 1, 1972

By S. I. Freedman

Coal-oil mixture (COM) combustion technology is regarded by the Department of Energy as near term, and potentially applicable to existing utility and industrial steam generators and for injection into blast furnaces. From work done previously, it has been established that COM can be burned in existing boilers, into blast furnaces. Therefore, the issues being addressed by the current DOE program are: (1) determination of best available technology to achieve environmentally-acceptable long-term reliable operation and (2) determination of applications for which COM can be utilized economically. Some of the technological options have begun to be determined by projects already under way. However, many projects are still in the early stages of development.

Jan 1, 1978

By Frederick A. Subosits

The Lithium Corporation of America's Hallman-Beam spodumene-pegmatite open pit mine is located in the Kings Mountain area of North Carolina. Figure 1. Presently this area of North Carolina is the lithium center of the U.S., if not of the whole world. The Lithium Corporation mine was started in 1968 and now covers 61,000m2 (15 acres) with projected are reserves in excess of 20 years. Lithium occurs at the Hallman-Beam property in a mineral known as spodumene (LiAlSi2O6), a lithium aluminum silicate. The run-of-mine are averages 1.43 Li2O. Figure 2 of the general Mining Division flow sheet follows the concentration of the Li2O to 5.5% and also lists the various by-products that are sold commercially. The unique properties of lithium have led to many commercial applications, some of these including lubricating greases, ceramics, glasses, glazes, welding fluxes, aluminum reduction cells, dehumidifying and air-conditioning equipment, sanitizers, polymerization catalysts, batteries, and pharmaceuticals. (3) (5)

Jan 1, 1978

By William R. Oakley

In order to best-discuss the met spar industry let me take the liberty to review our involvement, that is, my company's. Our organization has been involved in the fluorspar industry for approximately thirty-five years. We started our activity in Western Kentucky as a mining company and a beneficiator of spar, that is, grinding and grading. After a few short years, the mine became contaminated and rather than invest in a flotation plant, the property was sold and our spar activity was moved, primarily to Mexico. It was decided not to establish ourselves as a Mexican corporation, so, it was necessary to take the position of backer-financier of numerous mining operations. We served in this capacity for quite some time. We also built processing plants on the border in Texas, that is, sizing, grading, etc. in order to market into the steel industry. In 1957, generally speaking, fluorspar for the steel industry was purchased as gravel fluorspar with a maximum of 10% -1/16". The price of this material was $23.50 to $24.00 per ton f.o.b. railcar at the Rio Grande Crossings and about $26.00 or $26.25 f.o.b. barge, Brownsville, Texas. Usually the material was purchased on an effective basis. As you know, 2-1/2 times the silica total, subtracted from the total CaF2 gives the effective calcium fluoride. This was normally the extent of the chemical specifications. Consequently, material was shipped with no regard whatever, to anything other than effective units. The variations in material was absolutely unbelievable. In addition to this, quite frequently, cars were shipped, as they say in the industry, topped. This being, good material placed in the top of cars or barges over bad or low grade. The entire shipment may very well have met the effective unit spec, but the complete imbalance of the sub grade vs. the high grade more or less guaranteed that the consumer was probably using a great deal of low grade and therefore, his usage had to be way higher than it should have been. He came to the conclusion, that because of these conditions and the new technology developing in the steel industry, it was just a matter of time that the entire raw material industry would have to improve. Rather than spend our efforts directed to a substitute flux, we put together a sizing and grading plant in order to ship a controlled crude product, with independent laboratory analysis confirming size and quality. The age of control was started. We began shipping 70 to 72-1/2, 80 and 85 effective with sizing 1/2" by 2", 1" by 3", and 2" by 5" with absolute control on the amount of fines. A material with no fines was a premium product. Incidentally it sold for $24.50 -60 effective up to $28.50, $29.50 for 80 effective.

Jan 1, 1978

By Elisa Comis, Jeffrey Peterson, Yama Ebrahimi

Construction of the Northeast Boundary Tunnel (NEBT), the last leg of the Anacostia River Tunnel System on DC Water’s Clean Rivers Project, started in September 2018 and was completed in April 2021. The 26-foot-bore earth pressure balance (EPB) tunnel boring machine (TBM) mined 26,737 feet at elevations between 80 to 160 feet belowground. Approximately 55% of the tunnel was cut through lower predominantly coarse-grained facies identified as the Cretaceous Patuxent Formation (undifferentiated) (PTX), and the remainder was cut through upper predominantly overconsolidated fine-grained plastic material facies identified as the Cretaceous Patapsco/Arundel Formation (P/A). Mixed face conditions were encountered in the transition from the P/A to the PTX and vice versa. This paper reviews the performance of the TBM that mined the NEBT through several unique challenges, including 8,000 feet of tunneling under the heavily developed Rhode Island Avenue corridor, major sensitive structures, cast iron water distribution mains, and other sensitive utilities.

Dec 1, 2022

By George F. McKeregahan

Phosphate production of the Central Florida Phosphate District has been predominantly from the unique and lucrative Bone Valley Formation, with local and minor amounts coming from the underlying Hawthorn Formation. As the Bone Valley is depleted, replacement production will move progressively into areas of total Hawthorn Production. Significant changes in the characteristics and make-up of the deposit dictate required modifications in mining and beneficiation. Failure to tailor technology to fit the deposits of the future will result in vast "reserve" losses. In the Southern Extension of the Central District - two distinct "ore types" exist. These are presently referred to as the upper (high grade) zone and the lower (low grade) zone. The upper zone is somewhat similar to the Bone Valley Formation and will respond favorably to present beneficiacion practices. The lower zone is strikingly different and its response to conventional beneficiation is not acceptable. The major differences are in grain size distribution and mineralogical make-up of these grains. The Hawthorn differs from the Bone Valley by exhibiting lower grades, lower tonnage yield per acre foot, lower pebble percent of product, higher mining ratios, higher slimes (-150 mesh) content and deeper mining depths. Physical characteristic changes include more frequent occurrences of competent bands or lenses of "limerock" which are submarginal in value.

Jan 1, 1983

By Yuexin Han

The characteristics of comminuted hematite products using a high pressure grinding roller (HPGR) and conventional jaw crusher (JC) were comparatively studied by screening, optical microscope, scanning electron microscope (SEM) and Brunauer, Emmett and Teller (BET) techniques. Major properties investigated included product size distribution, particle cracks, specific surface areas and pore volumes. Results showed that in a closed-circuit operation with a screen opening of 3.2 mm, the HPGR and JC gave a similar P80, but the HPGR achieved a more uniform size distribution, more fines and a higher crushing efficiency. Three modes of cracks were identified, namely transgranular cracks, innergranular microcracks and intergranular microcracks. Transgranular cracks originated from shearing breakage. Innergranular and intergranular microcracks were generated by HPGR via the two main nonrandom breakage forms, preferential breakage and interfacial breakage, depending on their respective ability to endure stresses when mineral phases (particles) were loaded against each other. The BET values for the same-size fractions showed that HPGR products gave higher specific surface areas and more pore volumes than JC products. This indicates that HPGR-crushed products are easier to grind because of their high porosity and extra cracks.

May 1, 2012

By Mark Leggett, Kevin Roberts

The need to modernise and increase the safety provision of older road tunnels raises challenges in maintaining the operation of the tunnel during such improvement works. The Mersey Kingsway twin road tunnels located in Liverpool UK, constructed in the late 1960s, have had three new cross passages constructed to allow emergency evacuation from one tunnel to the other tunnel and provide safer access for emergency services. The 3200m long road tunnels are lined with an unusual reinforced concrete steel-faced segmental lining with a paint finish. Construction of the cross passages occurred during night possessions with the tunnels returned to normal operation during the daytime. Constructed through water bearing sandstone and lined with precast concrete segments, the passages required advance ground treatment and support works. This paper presents the historical background to the Mersey Tunnels and describes the procurement strategy, design and construction approach adopted for these important safety improvements.

Jan 1, 2003

By D. W. H. Su

"This paper presents the results of a comprehensive study conducted by CONSOL Energy, Marcellus Shale Coalition, and Pennsylvania Coal Association to evaluate the effects of longwall-induced subsurface deformations on the mechanical integrity of shale gas wells drilled over a longwall abutment pillar. The primary objective is to demonstrate that a properly constructed gas well in a standard longwall abutment pillar can maintain mechanical integrity during and after mining operations. A study site was selected over a southwestern Pennsylvania coal mine, which extracts 1,500-ft-wide longwall faces under about 600 feet of cover. Four test wells and four monitoring wells were drilled and installed over a 125-ft by 275-ft centers abutment pillar. In addition to the test wells and monitoring wells, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 1,500-ft-wide longwall panels on the south and north sides of the abutment pillar were mined by. To evaluate the resulting coal protection casing profile and lateral displacement, three separate 60-arm caliper surveys were conducted. Prior to the longwall panels being mined by, a number of 3D finite element simulations were conducted to estimate subsidence at the surface, coal pillar pressure increases, the resulting coal protection casing profile and displacement, and the vertical and horizontal displacements in the four monitoring wells. Comparisons of the pre-mining 3D finite element simulation results and the surface/subsurface/underground instrumentation results show that the measured test well and IPI casing deformations and profiles are in reasonable agreement with those predicted by the 3D finite element models, and that the measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models, which serves to validate the 3D finite element models. Parametric studies employing the validated 3D finite element models demonstrate that larger coal protection casing thickness is expected to have little effect on the lateral deformation, although it may reduce the magnitude of casing plastic deformation, and under deeper cover (~1,100 feet), lateral casing deformation is expected to be smaller, although larger plastic casing deformation may be present near the seam level. Also, evaluation of various casing and cementing designs using the validated 3D models clearly indicates that, when all casings are grouted to the surface except the intermediate and production casings, the intermediate and production casings show little deformation and no plastic strain. This research represents a very important step and initiative to utilize the knowledge and science obtained from mining research to improve miner and public safety as well as the safety and health of the oil and gas industries"

Jan 1, 2017

Strainburst phenomena, generally characterized by a sudden release of energy in a volume of highly stressed rock, are often encountered in such situations like crown pillar bursts in cut-and-fill mining, face bursts at development headings and floor bursts in deep shaft sinking. This paper describes a simple FE modeling approach which leads to the calculation of the energy release rate (ERR) and the total energy storage rate (TESR) in the rock mass around the openings. The merits of using such energy parameters in the analysis of strainburst problems to identify areas of high energy release/storage are discussed. However, much site-specific back analyses are needed to better understand how strainbursts and energy parameters are inter-related.

Jan 1, 1998