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By Greg J. Hasenfus, Allison M. Haines, Joshua M. Silvis

The floodable volume of longwall gob can be of great importance in developing accurate coal mine operation plans, particularly for mine water management and environmental control strategies. Given the inaccessibility and difficulty in direct measurement of gob characteristics following gob recompression, hydrologic, geomechanical, and spatial data and principles were used to solve for the porosity and height of the residual gob using a mathematical model framework and bulking-based techniques. Based on this approach, gob porosity of Appalachian longwalls appears to be tighter than previously reported, ranging between 4.99 and 14.31%. Residual gob height, as normalized with respect to mine extraction height, ranges between 1.90 and 2.45. A novel, bedding-based bulking approach is ampliative with respect to existing roof caving and bulking fundamentals, as it has greater explanatory value compared with the traditional, lithologic-based bulking application. The efficacy of using the residual gob characteristics determined by the mathematical model and bedding-based bulking is examined using a causal comparative method, whereby time series prediction of historical groundwater rebound is compared with observed mine pool elevation data. Prediction accuracy is significantly improved using a prototype model to calculate void volume of longwall gob, specifically, the dependence of porosity of the gob material upon the longwall width to overburden depth ratio for movement basins of subcritical and critical panel widths. The potential implication of these findings toward hydrologic, geomechanical, and ventilation studies of longwall gob could be significant.

Aug 13, 2021

By J. Mácsik, J. Lindblom, C. Maurice, Susanne Nigéus

Using non-hazardous industrial residues in mine waste remediation is beneficial not only for the mining industry where substantial amounts of the waste generated have potential to produce acid rock drainage and pollute the environment, but also the providing industry, minimizing the waste landfilled. In this study green liquor dregs (GLD), residue from 15 different paper mills were characterized to valorize it as a potential product as a cover material. In another part of the study, one of the GLDs and a local till were characterized to determine the optimal mixture of GLD amended till to be used in a field application at the closed Näsliden Mine in northern Sweden. The study concluded 10% GLD-amended till to be the optimal recipe and was successfully applied at the Näsliden mine waste dump. However, the great variability in the characteristics of GLD creates challenges if it is to be valorized as a product.

Dec 7, 2023

By Calvin J. Konya

An investigation was performed to determine conditions which optimize fracture formation between blastholes used for purposes of pre-splitting. Experiments-involved high-speed photography in Plexiglas models and radiographs in sandstone models. Additionail data was obtained from full-scale pre-split blasts. Pre-split fractures between blastholes were found to form as a result of gas pressure and were affected little, if any, by stress wave interactions. Pre-splitting was effective with short period delays of 25 milliseconds or less, and did not require instantaneous initiation of blastholes. Significant reduction of ground vibration resulted with the use of delays

Jan 1, 1980

By M. Misra

The dielectric properties and flotability of different ranks of Argonne Premium Coal samples are presented. The flotability of different ranks of coal are correlated with the dielectric properties and intrinsic moisture (or bound water) content. Measured dielectric properties of as-received coals and other constituents are incorporated into a mixture equation to calculate the dielectric properties of bound water present in the different ranks of coal. The nature of bound water present in low-rank hydrophilic coals is significantly different from that present in high-rank hydrophobic coals. The water molecules present in low-rank lignite have an oriented dipole-dipole interaction and are tightly bound to the surface. For high-rank coals, the water molecules are not bound to the surface and have a randomly distributed clathrate ice-like structure. Controlled thermal treatment can modify the structural nature of bound water present in low-rank hydrophilic coals and increase their flotability.

Jan 1, 1990

The segregation process has been known for many years and applied industrially for the treatment of various refractory copper ores. The principles of the process are briefly reviewed; the process was tested in the laboratory on two copper-cobalt oxide ores from Gecamines, Shaba Province, Zaire. Various parameters of the process, such as segregation temperature, dosage of reducing and chloridizing agents and flotation conditions were inyestigated. Experimental results have shown that the segregation of copper could proceed satisfactorily at low temperature (1000° K) but that of cobalt required higher temperature and higher additions of reducing and chloridizing agents.

Jan 1, 1992

By SAHENDRA SINGH, SANJIT KUMAR PAL, DHARMITA HORO

The North Singhbhum Mobile Belt (NSMB) lies between two crustal-scale shear zones, the South Purulia Shear Zone (SPSZ) at the north, and the Singhbhum Shear Zone (SSZ) at the south. The Babaikundi-Birgaon Axis (BBA) is an east-west trending secondary shear zone in the NSMB lying south of SPSZ, which is known for the occurrence of gold along with other sulfide minerals within the quartz reefs. The present study has been carried out at north of Ichadih village, which lies on the BBA. The present study attempts combined electrical resistivity tomography (ERT) and self-potential methods along a profile of 470-m length in the Ichadih area to map the potential mineralized zones. Initially, ERT sections generated by Wenner, Wenner- Schlumberger, dipole-dipole, and joint inversion of the combined array have been analyzed, and results are validated through the analysis of model resolution. A prominent low resistivity (10–100 Ωm) associated with quartz reef/limonitic quartz reef at a depth of approximately 30–85 m, encircled by a high resistive (more than 10,000 Ωm) formation associated with metasedimentary rock, has been delineated using joint inversion of the combined array. Further, analysis of self-potential (SP) anomaly using particle swarm optimization inversion also confirms the prominent low SP anomaly at a depth of 77.3 m, which is analogous to the low resistivity anomaly identified in the joint inversion of the combined geo-electric array. Subsequent analysis of a complex synthetic geo-electrical model analogous to the present field situation proves the efficacy of the joint inversion of combined arrays. As a whole, joint inversion of multi-array data is established as an efficient technique for better subsurface imaging in case of the complex subsurface structure. In-depth analyses confirm the possibility of sulfide mineral-rich deposit (quartz reef/limonitic quartz reef) which requires further geological drilling and lithogeochemical sample analysis, for possible future exploration.

Oct 26, 2020

By Wallace Macgregor

The direct investment role of Middle Eastern oil producing countries in future world-wide mineral development probably will be a limited one for the next five years. Their needs and their longer range economic objectives substantially preclude any such risk taking ventures. There is, of course, the possibility of political in- vestment. One hears many rumors and doomsday calculations of what the Arabs might do with the rising accumulation of surplus funds. Up to now, this kind of investment has been more in rhetoric than in money. For the most part, oil producing countries of the Middle East have been, and will be, investing surplus funds with strong emphasis on the preservation of capital. They will seek security first and yield second just like any other prudent investor. In several respects, this is regrettable. A direct infusion of risk capital into mineral development, especially in the Third World countries, is a constructive way of enhancing their earning power which many desperately need just to stave off starvation. It would also be a good way of eliminating material shortages in the industrialized world. Most important of all, it would help to ultimately reduce inflation without imposing the hardship of recession. So why isn't it done?

Jan 1, 1975

By Gary P. Thomason

We have all heard a great deal about how various projects were financed or certain companies were successful in obtaining a bank loan. There are many more projects and companies who fail to get the money they need. At least a portion of these failures, and a large percentage of the frustrations connected with even the successful financings, are a result of not understanding the process of obtaining money. Recent years have seen a proliferation of sources available to finance minerals operations, but let me assure you that these represent only a minor portion of the minerals financing market. The fundamental source of borrowed money to almost all minerals related companies remains the banks. Therefore, understanding the "Loan Approval Process" can easily mean the difference between getting the money or not. In the following pages I hope to provide some insight into what I define as the loan approval process. Having pre-offered my definition, I intend to delineate the various stages of the process and the planning and information I believe should be contained in each. My ultimate goal is to help you think like a banker and, in so doing, stay on top of the process so that you can successfully obtain the funding necessary for your projects.

Jan 1, 1983

By MOHAMMAD R. H. GORAKHKI, CHRISTOPHER BAREITHER, MANUEL APARICIO, IV JOSEPH SCALIA

Comingling filtered tailings and waste rock in a tailingsdominated mixture is a mine waste management strategy that has the potential to create geotechnically and geochemically stable landforms. Potentially acid-generating (PAG) waste rock can be sequestered within a filtered tailings matrix to enhance water retention and decrease hydraulic conductivity relative to a waste rock pile, potentially minimizing acid rock drainage (ARD). Enhanced water retention can reduce oxygen ingress limiting oxidation and resultant acid generation. Reduced hydraulic conductivity can slow inward percolation and outward drainage. In dry climates, the tailings matrix can hold precipitation near the ground surface accessible to evaporation and transpiration, thereby decreasing percolation. This paper presents an evaluation of comingled filtered tailings and waste rock in a tailings-dominated mixture (termed GeoWaste herein) and illustrates that ARD can be reduced under field conditions in a subtropical–highland climate.

By Caibin Wu, Bin Xie, Jiaqi Tong, Ningning Liao, Chong Zeng

Understanding the energy-size reduction relationship is vital to grinding process; therefore, this paper aims to show the energy-size reduction of magnetite-calcite binary mixture in a laboratory wet conical ball mill. Single magnetite, single calcite, and blended magnetite-calcite mixture at three weight ratios in four particle sizes were ground in a laboratory wet conical ball mill at four grinding time periods. The results showed that the particle size distribution of both fine particles and coarse particles of single and mixture ground product fitted well with the PSD computed by Rosin–Rammler-Benne function. The larger mass percentage of calcite is, the higher t10 of binary mixture ground product is. On the contrary, t10 in the mixture decreases as the percentage of magnetite in the mixture increases. The different breakage behaviors in blended samples are due to the hardness and particle size. The results of calculated ratio of energy absorption factor showed that the calcite consumed more energy in the breakage process of binary mixture than ground alone. The JK size-dependent breakage model based on the t10 method fits all the experiment data, be it generated from pure minerals, mixtures at different weight ratios, or each component separated from the mixture.

Jun 4, 2022

By Renfeng Song, Shaoyan Wang, Zhiqiang Zhang, Ke Guo

Leaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

Jun 16, 2021

By J. Hanna

The University of Alabama Mineral Resources Institute (MRI) has developed a unique process for selective fatty acid flotation of carbon-ate gangue from sedimentary apatites "francolite" in the pH range of 4-6 without collector conditioning of the pulp. The process, which does not require an apatite depressant, was modified to beneficiate a high Mgo siliceous phosphate matrix from south Florida. The modified process includes two flotation stages, one for carbonate removal, as mentioned above, and the other for phosphate recovery from the siliceous gangue. The selective flotation separation of the carbonate and phosphate, from siliceous constituents of the matrix at various pH levels and collector dosages are discussed. In the carbonate flotation stage, about 70% of the Mgo was rejected in the froth and the phosphate flotation stage produced concentrates analyzing about 31% P2O5,0.7% HgO and 4% insol. The overall P2O5 recovery in the two stages is about 85%.

Jan 1, 1989

By R. E. Lindstrom

The mineral bastnasite is utilized to describe alternate processes for the extraction and separation of the rare-earth elements by solvent extraction. The rare earths can be acid-leached directly or fused with NaOH before acid leaching. Cerium, the major constituent, can be recovered by fractional precipitation, fractional leaching, or solvent extraction with tri-nbutyl phosphate. The latter process is capable of producing 99.5-percent pure CeO2 at 98+ percent recovery. Lanthanum is subsequently recovered by fractional precipitation or solvent extraction with a nitrogen-based extractant. A 20-stage mixer-settler operation with a primary amine extractant results in a 95-percent pure La203 fraction at 96 percent recovery. Europium is amenable to extraction from most of the remaining rare earths with an organophosphate extractant. Selective stripping of the europium, followed by reductive precipitation, produces high-purity Eu203. Another possibility for europium purification involves the differential extraction of europium with an amine followed by a sub- sequent reducing strip. Separation of the remaining elements is more difficult but can be accomplished with amine or quaternary ammonium extracts. Typical separation factors achieved are 3. 8 for praseodymium-neodymium and 10. 5 for neodymium-samarium.

Jan 1, 1967

By R. F. McFarlin, H. E. El-Shall

Since its inception, the Institute of Phosphate Research has examined every promising proposal in order to find an economical, practical and environmentally sound method of dewatering phosphatic clays. The in-house development of the FIPR/DIPR process (DIPR = Dewatering Instantaneously with Pulp Recycle) would appear to answer that quest. When small amounts of fibrous materials are mixed with clay slurries and flocculent, rapid dewatering occurs. Clay solids contents of 20 to 25% can be attained by simply rolling the clay mass down an inclined screen. Higher solids (>40%) are reached by physically pressing the cake; e.g., with a belt press. Because mechanical pressing devices are too expensive for phosphatic clay treatment, FIPR has developed the "sandwich" method of simultaneously dewatering the phosphatic clays and reclaiming the mine cut, as well as a second alternate, the "median strip" proposal. Economic projections of these bench-scale alternates suggest that the FIPR/DIPR process should be no more costly than present practice, when credit is given for the simultaneous reclamation accomplished.

Jan 1, 1993

By N. Merriam

This report describes Koppelman's work to develop the K-Fuel® Series C Process used to dry and stabilize Powder River Basin coal. It also contains summaries of the results of bench-scale and pilot plant tests conducted to prove the Series C Process. The process is being used by the KFx-Thermo Ecotek partnership for a 500,000 ton per year commercial plant that has been constructed near Gillette, Wyoming. The plant is presently undergoing shakedown.

Jan 1, 1997

By Paul Dean Proctor

The world's population by 2000 A. D. may approximate 6.5 billion and the United States' 304 million. South Asian population increases between 1970 and 2000 A. D. will be triple the projected population of North America. Such anticipated dramatic and probably traumatic increases in world population yield grave concern for the standard of living in the world and the United States. The people of the United States currently consume 32 percent of the world's energy and similarly large percentages of the world's mineral raw materials. With only 6 percent of the present world's population and slightly smaller percentage by 2000 A. D., much expanded world-wide production of energy and raw materials will be required to maintain even a standstill living standard. A minimal 2 percent increase per year in the standard of living in the United States and a 4 percent increase elsewhere in the world, beyond the demands of the estimated population increases, suggest the magnitude of the increased need for energy-mineral raw materials and the possible crises the world will face in these areas by 2000 A. D. Mineral engineers and scientists with broad educational backgrounds will be required in greatly increased numbers to help alleviate, and possibly avert, expected energy-mineral raw materials shortages of the next millenium. Explorationists, mineral engineers, commodity economists, environmentalists, city, county, state, and federal mineral materials planners and coordinators, and metallurgists will be among those most needed. AIME membership in the second century of the Institute's history will contribute directly to this personnel pool.

Jan 1, 1971

By Giovanni Barla

This paper examines the application of gelatin mixture models to the study of factors such as gravity effects, tectonic and residual stresses, anisotropy, physical nonlinearity, time-dependent behavior of the rock mass and connectedness of the geologic space. The calibration technique of gelatin mixtures, proposed by Richards and Mark in 1966, is applied to the particular problem considered. Similitude relationships between model and prototype are discussed with reference to the constitutive equations describing the physical behavior of the rock mass. The interaction between two openings in a linearly elastic medium, under conditions of plane strain, is used as an illustrative example, with the view of describing the history of stress and deformation changes on the rock medium and lining around a slusher drift while undercuts are made in block caving.

Jan 1, 1968

By K. Anim, C. Calderon-Arteaga

Located in Mojave, CA, The Soledad Mountain mine is an Open pit Heap-Leach gold Mine, which is operated by Golden Queen Mining Company LLC. under private capital. Open pit mining began in 2015 while full production was reached in 2016. The open pit mine feed a processing plant that can process more than 13K tons per day of ore which is sent to a heap leach pad. The Soledad Mountain project is a poly metallic deposit with Au and AG being recovered as payable metals. As the mine became bigger after moving to the east pit phases, Golden Queen was facing new challenges to control the production and accurately determine KPIs to improve/increase the production. To maximize returns and asset value, a new fleet management system (FMS) was adopted and implemented. The new FMS has enabled the mine to interconnect the different stages of the mining, as well as to recognize issues and implement the necessary corrections. With the associated increase in complexity in the process, the requirement of the ore control system to accurately predict ore feed characteristics is critical to maximizing metal recovery. Implementation of new daily and weekly plans were needed to ensure the ore delivery and meeting the tonnage goals, while allowed the equipment operators to better geolocate and to maximize the equipment production. These conditions alongside with Golden Queen’s drive to increase profitability and maximize net asset value has created challenges. These challenges are numerous and multifaceted. However, the ability to accurately route the material from the mine, is critical to site success and some of these challenges have been overcome by the adoption of the new FMS, the implementation of daily and weekly plans and upgrades in the ore control workflow. Examples of how the integration of the new systems allowed golden Queen to improve production strategy, are discussed in this article.

Mar 2, 2022

By R. A. Seitz

This paper presents a framework for analyzing the theory and industrial practice of coal flotation and gives some examples of its use for understanding flotation phenomena and optimizing/controlling flotation circuit performance. It is based on extensive laboratory and in plant test work conducted over the past several years by researchers at MTU as well as an analysis of the literature. Previous researchers have usually considered either the surface chemistry or the kinetics of coal flotation behavior, only rarely have these factors been considered together. However, these factors must be considered together in order to gain a clear understanding of the theory underlying coal flotation such that its practical application can be optimized. Fortunately, this complex objective can be achieved by considering the recovery and rate of recovery of the different types of particles present in the feed to coal flotation circuits and the fundamental mechanisms responsible for these recovery phenomena. The influence of three major groups of variables must be considered: control variables (reagent additions, aeration rate, etc.); disturbance variables (feed pH, percent solids, etc.); and circuit design variables (number of cells, circuit arrangement, etc.). Each of these groups of variables affects process kinetics in a clearly understandable manner, which, once determined, is extremely useful in circuit design and optimization. This paper includes a discussion of the use of the proposed framework to explain the effects of some coal characteristics on flotation performance. In addition, an example of using this analysis to optimize the performance of a coal flotation circuit using frother and collector addition levels is included.

Jan 1, 1985

By Guodong Li, Chenlin Wang, Zibiao Yu, Bo Xu

Abandoned coal mines have many underground space resources, such as roadways, shafts, and gobs. Among them, abandoned roadways are the best gas storage space for underground compressed air energy storage (CAES). However, CAES caverns have high air pressure and strict sealing requirements. Therefore, the stability and sealing of abandoned roadways under high internal pressure must be analyzed. Afterward, the suitability of abandoned roadways used for CAES caverns should be evaluated. In this study, the numerical simulation software FLAC3D was used to calculate the stress, deformation, plastic zone volume, and pore pressure of surrounding rock in an abandoned roadway under 10 MPa internal pressure. The influence of buried depth, surrounding rock grade, and in situ stress state on roadway stability and the effect of surrounding rock permeability on roadway sealing were analyzed. Results showed that the stress, displacement, and plastic zone volume of surrounding rock were affected by high internal pressure when the buried depth was less than 300 m, but high internal pressure had little effect on them when the buried depth was more than 300 m. The suitable range of buried depth was more than 300 m. The optimal choice of surrounding rock grade was I and II, followed by grades III, IV, and V. The optimal choice of in situ stress state was σH > σh > σv, followed by σH > σv > σh and σv > σH > σh. The sensitivity of the stability evaluation parameters was ranked in descending order as follows: buried depth, surrounding rock grade, and in situ stress state. When the surrounding rock permeability was less than 1 × 10− 14m2, the 24-h air leakage rate of the roadway was less than 1%. The suitable range of surrounding rock permeability was less than 1 × 10− 14m2.

May 23, 2023