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By Wen Tao Liu, Tong Tian, Fu Sheng Niu, Xiu Man Liang

The level of automation employed in flotation production is relatively low. In an actual concentrator, operators use their judgment to adjust the production state based on the visual characteristics of the flotation froth surface. There are shortcomings, such as strong subjectivity and lagging process operation, that easily cause the waste of manpower and material resources. Machine vision technology is introduced to replace human visualization, achieving a quantitative description of the visual characteristics of the froth surface. The state variable parameters are provided for the identification of the flotation conditions.

By B. Mishra, Q. Shi

Numerical simulations have been used to investigate roof fall in the past decades. Comparing to the continuum based methods, the discrete element method has been well recognized for its excellent performance in simulating large strain problems and fracturing processes in the rock mass. However, the discrete element method has its limitations. When simulating a large-scale problem, a large number of particles are required, which consumes significant computational resources. In the present study, a 3D numerical model coupled with the finite-difference method (FDM) and the discreteelement method (DEM) was created to simulate the laminated roof failure in an eastern coal mine in the US. In the FDM-DEM coupled model, the laminated roof of the entry is represented by an assembly of bonded particles using PFC3D. The laminated roof is simulated by adding parallel discontinuities. The discontinuities are given certain stiffness and strength in the model. The ribs, floor, and far-field surrounding rock are represented by continuum zones using FLAC3D. The strength of the discontinuities is varied sequentially and the fracturing of the laminated roof was analyzed with respect to entry advance. The results showed that the laminated roof fractures along the discontinuities while an intact roof fractures in a dome shape. Increasing the strength of discontinuity could enlarge the tensile zone inside the laminated roof and hence change the crack distribution. In addition, the crack quantity in the laminated roof behind the advancing face decreases with the increment of discontinuity strength while this trend is not occurring ahead of the advancing face. The simulation demonstrated that coupled method using PFC3D/FLAC3D can reproduce the laminated roof failure in underground coal mines.

Mar 2, 2022

By K. P. Chong

Fracture toughness of oil shale is an essential property in fragmentation to optimize particle sizes and permeability distributions in in-situ processes. Fracture mechanics of oil shale has been based on conventional fracture mechanics using notched samples and assuming the material to be isotropic and elastic. Oil shale is a layered material more accurately characterized as transversely isotropic. The senior author proposes to use a semi- circular core specimen with a center crack subjected to three point bending. Singular crack tip elements with isoparametric elements are used. The precracked semi-circular disk is modeled under displacement loading. The effect of crack length on the non-dimensionalized stress intensity factor is investigated by strain energy method, ellipse method, and stress method. Very close agreements are found. The fracture toughness is obtained by compressing the specimen in to failure. Parameters such as oil yield are investigated.

Jan 1, 1984

By Reynold Q. Shotts

Underground mines, penetrating well below the water table, quickly fill with water when abandoned. Ordinarily, these natural cisterns are not thought of as sources of industrial water. Under special circumstance, if chemically treatable, they might become valuable industrial water reservoirs. An example of a group of about 20 mines in a geological and structural setting insuring water entrapment, rapid recharge and a possible minimum of contamination, are the small, compact Belle Ellen and Piper basins in Alabama's small but second most productive coalfield, the Cahaba. The mines have been abandoned from more than 50 to less than three years. The county now produces about a million tons of coal annually, all from strip mining. Figure 1 shows an idealized cross section of the strata in the Belle Ellen syncline near West Blocton, Bibb County, Alabama. Figure 2, 3 and 4 are maps showing the location of the syncline, other structural features, the outcrop lines of the three principal coalbeds underlying the basin, and the mined-out areas on the three beds (1).

Jan 1, 1973

By J. F. Snyder

Minor elements determined by atomic absorption spectroscopy include: zinc, cadmium, copper, cobalt, nickel, chromium, manganese, and iron. Of these elements, only three; zinc, cadmium, and copper are found to have been introduced with the ore-forming fluids. Iron, manganese, chromium, and nickel were increased in dolo-stone lithologies when compared to limestone lithologies. The uniform distribution of cobalt suggests this element was neither increased nor decreased during ore emplacement nor during dolomitization of the rocks. Zinc increases adjacent to ore result from leakages into open spaces rather than as pervasive aureoles surrounding ore bodies.

Jan 1, 1977

By T. Sun, J. Kou, D. Tao

"The reduction behavior of low-grade lump hematite ore (100% 20-50 mm) has been evaluated by performing a series of coal-based direct reduction roasting tests followed by magnetic separation under different process conditions such as roasting time, temperature, reductant type and dosage, and grinding stage. To investigate mineralogical transformation and reduction characteristics of lump hematite ore, roasted ores and magnetic concentrates were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and polarizing microscope. The results have shown that a magnetic concentrate with a total iron (TFe) grade of 90.7% was produced at an iron recovery of 83.9% when lump hematite ore was reduced at 1,200° C for five hours using 35% lignite as a reductant followed by two stages of grinding, for 20 min and 30 min each, and low-intensity magnetic separation. The degree of reduction is closely related to the change in the internal structure of the roasted ore. Lignite with a higher fixed carbon content and lower ash generated roasted ore with a more highly porous structure, which provides better permeability of reducing gas. Magnetite, fayalite and wustite were the dominant intermediates of coal-based direct reduction of lump hematite ore. Parts of wustite reacted with SiO2 or Al2O3 in gangue and generated fayalite or hercynite. FeO in fayalite was replaced by CaO to produce wustite, which was finally reduced to metallic iron. However, Fe in fayalite and hercynite produced with low contents of CaO cannot be reduced into metallic iron. Introduction Low-grade hematite ore, characterized by low Fe content and high SiO2 content, cannot be treated by traditional mineral processing methods due to its nonmagnetic property and fine liberation size. The direct reduction (DR) roasting process has been studied and proven satisfactory in treating difficult-toprocess ores, such as low-grade nickel laterite oxide ore (O’Connor et al., 2006; Cao et al., 2010; Guo et al., 2011), high phosphorus oolitic hematite ore (Li et al., 2012; Yu et al., 2013), low-grade hematite ore (Wei et al., 2013;) and iron ore tailings (Li et al., 2010), which greatly expand the resources of usable iron ores (Srivastava and Kawatra, 2009). Therefore, the use of a DR process to treat low-grade hematite ore to produce direct reduced iron (DRI) is of great interest to many researchers of mineral processing and metallurgy (Weissberger et al., 1986)."

Jan 1, 2015

By G. L. Brooke

At present, there are two known cobalt deposits in the 48 contiguous states. This paper is a brief description of one of these deposits. It is a Mississippi Valley type deposit, but somewhat atypical in that the metal of greater interest is cobalt as opposed to lead, zinc, and copper. The history and present work are outlined along with a discussion of the geology and mineralogy.

Jan 1, 1981

By Alper Kirmaci, Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Injuries and fatalities resulting from roof falls are still a major concern in U.S. coal mines, and many researchers are focused on developing meaningful approaches to minimize this hazard. In the United States, coal mine roofs can vary widely in composition, geometry, and inherent heterogeneity, leading to a wide array of different roof fall failure types. Researchers frequently employ numerical modeling tools to reproduce this physical phenomenon and provide key guides to engineers regarding roof conditions and control as long as the input data and constitutive relations are appropriately selected. Simulating such complexity requires expertise and constitutive models that adequately simulate roof behaviors. However, the currently available constitutive models have shortcomings in capturing some of the roof fall failure types common in underground coal mines, such as guttering. A new constitutive model is developed to address the shortcomings of constitutive models commonly used for coal roof stability analysis. The constitutive model developed in this study combines the anisotropic-elasticity and nonlinear strain-softening responses. In addition, the developed constitutive model can simulate up to three different joint sets implicitly, allowing for use in both continuum and discontinuum settings, and can be used in both Lagrangian finite-volume and distinct element method codes of Itasca. First, the mathematical expressions of the model are provided. Afterward, the validation phase of the developed model that covers comparisons with analytical solutions and those of existing models (e.g., anisotropic elasticity, ubiquitous-joint, and bilinear strain-hardening/softening ubiquitous-joint plasticity) is presented. Finally, a hypothetical coal mine roadway facing high horizontal stress is simulated. The presented model successfully shows three distinct stages of a cutter roof in a shale roof: (1) initiation of shear cracks at the rib– roof intersection, (2) extension of cracks deeper into the roof (i.e., above the roof bolt length horizon), and (3) cantilevered roof. It is demonstrated that the presented constitutive model has the potential to help future researchers in simulating various roof responses.

Jul 1, 2023

By C. Okrusch, C. Roos, M. Akers, S. Rosenthal

Modern mining consistently faces controversy. Public sentiment impacts the permitting and development of mines, so a quality public relations (PR) program for mining companies may improve society’s impression of the mining industry. Developing mines face more permitting challenges than operating mines, which stems from a lack of societal trust given the history of mining and its impact on the environment. Two case studies were selected based on the type of public controversy they face to demonstrate how pervasive permitting issues are in industry. Both Pebble Mine, owned by Northern Dynasty Minerals (NDM), and Black Butte, owned by Sandfire Resources America Inc (SRA), experienced difficulties with their water permitting due to potential risks their mine developments posed to local fish populations. Pebble has, to date, failed in all of their attempts to become permitted due to concern for the water and the fish. Black Butte dealt with the same problems, on a smaller scale, but was able to become permitted. These two mines will be discussed in detail including local history, mine setting, mining history in America, prevalent culture groups, technology development, and intercultural communication competence (ICC). The mining industry needs to evaluate its ICC skills since ICC directly determines the effectiveness of PR. Based on Barna’s Stumbling Blocks for intercultural communication, methods for improving the mining industry’s PR will be suggested in the hope of easing the permitting process for future mines by developing ICC.

Mar 2, 2022

By N. W. Stump

New developments in on-stream analysis using immersed radioisotope gauges including results from plant installations are described. The control of grinding and flotation using a small digital computer has been complemented by this development. A control scheme for grinding which is based on maximum throughput at constant product size and preliminary work in flotation control are also outlined.

Jan 1, 1974

By Paul E. Rosten

This paper describes some of the latest improvements that have been incorporated or planned by the Cleveland-Cliffs Iron Company to reduce operating costs and improve pellet quality. The Cleveland-Cliffs Iron Company operates and manages mining, beneficiation, and pelletizing operations in Michigan, Canada, and Western Australia. This paper deals with the grate-kiln pelletizing operations at Republic, Humboldt, Tilden, Empire, and Pioneer in Michigan, and the Adams and Sherman in Ontario, Canada. Table I characterizes .each operation in regard to location, ore type, pellet capacity and date that pellets were first produced. All of the operations with the exception of Pioneer and Tilden, utilize downdraft-two-pass grate cycles of drying followed by preheating. Pioneer utilizes an all-downdraft, three-pass grate cycle which consists of three drying zones followed by the preheat zone. The Pioneer and Tilden cycles have been described previously. (1) (2)(3) Tilden utilizes a three-pass grate cycle with a stage of updraft drying, followed by two downdraft drying stages. Recuperation systems which supply hot gases to a drying zone from second stage cooling were designed and furnished for Tilden I. Tilden II will be identical. Empire IV will also be furnished with a recuperation system. The Adams grate-kiln system was retrofitted with a recuperation system. This paper will summarize some of the efforts that are in effect or planned for grate-kiln pelletizing systems to (1) reduce operating and maintenance costs, (2) reduce energy requirements, (3) improve product quality, and (4) meet environmental standards.

Jan 1, 1977

By B. A. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformation. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, timelapse point clouds of mine workings. In order to determine sloughage volumes and locations, two sets of laser scans were performed 42 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds. Volumetric changes of 2.3-2.6 m3 were detected on rib faces during the time-lapse study. In addition, displacement in the mine roof was, as expected, not detected, suggesting well surveyed scans and an appropriate scan resolution.

Nov 1, 2013

By Shawn P. Coughlin, Michael A. Schimmenti, Juan Leonardo Tello del Pino

"The Sistema de Potabilización Área Norte project (Northern Area Purification System) was a major expansion of the potable water system in Buenos Aires Province, Argentina. The aim of the project was to transport and purify raw water from the Paraná River to provide potable water for five communities in the northern part of the province, benefitting up to two million people. The project was constructed by a joint venture (JV) of four South American contractors and consisted of the following key components:• Treatment plant: A 16-ha (39-acre) area was cleared for the construction of a treatment plant to purify 900,000 m3/day (1.2 million cu ft/d) of raw water from the Paraná River and distribute it to the surrounding communities.• Bored tunnel: Nearly 15 km (9 miles) of 3.6 m (12 ft) inner diameter tunnel, ranging from 18 to 22 m (59 ft to 72 ft) below grade, was bored with two earth pressure balance (EPB) tunnel boring machines (TBM) to draw the raw water from the river. The TBMs started from a central launch shaft and proceeded in opposite directions. Cristina advanced northbound to the Paraná River Intake System, and Liliana advanced southbound to the new treatment plant.• Access and ventilation shafts: Five access shafts and eight ventilation shafts were installed along the length of the tunnel. The access shafts were designed to provide entry points for inspection and maintenance of the final tunnel. The five shafts consisted of one central launch shaft in the middle of the tunnel alignment, one retrieval shaft at each end of the tunnel (intake and treatment plant, respectively) and two intermediate shafts. The intermediate shafts were installed before the TBM passed, with a final liner to be installedafterward."

Sep 1, 2016

By C. R. Montgomery

Coal companies in order to supply their customers En the metallurgical market, both home and abroad, must be able to control their production in order to meet carbonization specifications over and above those of the proximate analyses which has been the prime consideration of purchases in the past. It is the purpose of this paper to review in brief some of the tests used and give data to show the application of such as it applies to the customers needs. It is now recognized that coal is not homogeneous in any of its properties and an amazing fact is that it has been used for so long a time as the principal raw material for the manufacturing of coke without more emphasis having been placed on the variation between coals; yes, even from coals in the same seam at different geographical locations, Recently Kuchta and Clendenin pointed this fact out In a study of the(1) carbonizing behavior as related to chemical and plastic properties of Alabama medium volatile coal.

Jan 1, 1962

By Juan J. Monsalve, Mario Karfakis, AMAN SONI, Nino Ripepi, Jim Hazzard

Pillar collapses are events that due to their severe consequences can be classified as high risk. The design of pillars in underground room-and-pillar operations should migrate to risk-based design approaches. The authors of this work proposed a risk-based pillar design methodology that integrates stochastic discrete element modeling for pillar strength estimation, and stochastic finite volume modeling (FVM) for stress estimation. This paper focuses on the stochastic FVM component for stress estimation. The mining and geomechanical aspects of a case study mine (CSM) are described and pillar stresses are estimated by using three approaches: (1) analytical solutions, (2) 2D finite element modeling, and (3) 3D finite volume modeling. This operation extracts a 30° dipping deposit, which makes current underground stone mine design guidelines inapplicable for this CSM. This work compares results from each stress estimation approach and discusses uses the point estimate method as a simplified stochastic approach to evaluate the effect of rock mass elastic properties variability on pillar stress distribution. Results from this work show that the three estimation approaches lead to different estimations, possibly, due to the wide range of assumptions each estimation approach considers. It was also determined that the horizontal to vertical stress ratio has a significant impact on pillar stress magnitude. Therefore, it is recommended to perform in situ stress measurements, or assume worst-case-scenario values to account and reduce uncertainty due to this parameter. The stochastic stress estimation approach used in this paper provides results that can integrate a risk-based pillar design framework.

Sep 24, 2022

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dust escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dusthog- type bit to improve dust extraction during the critical initial phase of drilling. A twistedbody drill bit is also evaluated to determine the quantity of dust liberated in comparison with the dust-hog-type bit. Based on the results of our laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emission can also be substantially reduced. The use of a twistedbody bit has minimal improvement on dust capture compared with the commonly used dust-hog-type bit.

Jan 1, 2014

By P. Shang

Fly ash and zeolite have strong absorption to cations since their porous microstructure. The porosities of fly ash and zeolite can also be increased by modification, which improves the absorption of the materials. This research showed that the effects of modified fly ash and zeolite to remove ammonia nitrogen from rainwater. The optimal reaction time, additive amount of materials, and pH value of the stormwater to remove ammonia nitrogen were experimentally determined. For modified fly ash, the optimal removal rate of ammonia nitrogen from 100 ml stormwater was 74.41% with the addition of 10.0g fly ash, 1.5 hours of the reaction time, and 8 of pH value. To the modified zeolite, the optimal removal rate of ammonia nitrogen was 51.22% at the reaction conditions of 2.0g of zeolite, 1 hour of reaction time, and 7 of pH value.

Jan 1, 2010

By P. K. Parhi

The extraction of nickel has been carried out by the hollow fiber membrane technique using D2EHPA as the mobile carrier from the manganese nodule leach liquor after separation of Cu(II), Zn(II) and Co(II). The experiments were designed according to central composite design (CCD), which is a response surface methodology. The process parameters used for the experimental design were: pH, concentration of D2EHPA in the membrane phase, flow rate and H2SO4 concentration in the strip solution. Based on the analysis of variance, a reduced quadratic model was found to best fit the experimental data. The process parameters were optimized to maximize the nickel flux and the optimized conditions were flow rate: 630 mL/min; pH: 6.37; D2EHPA: 1.15 mol/L (1,150 mol/m3) and H2SO4: 2.39% (430.2 mol/m3), for a maximum nickel flux of 7.08 x 10-5 mol/m2.s, which was in good agreement with the actual Ni flux of 6.99 x 10-5 mol/m2.s.

By J. R. R. Bowling, A. McFadden, M. Francoeur

The abstract discusses the increasing use of extensive duct-fan systems in underground hard-rock mine development. It highlights the challenges of designing these systems, particularly the risk of partial vacuum and the need for careful booster fan positioning. The paper explores factors influencing the design of these systems, including component limitations, operational wear margins, and power constraints. It also defines the concept of partial vacuum and its impact on ventilation ducts. The authors propose an algorithmic approach for specifying the location and blade pitch of in-line booster fans to prevent system failure.

Mar 17, 2022

By Georgene Renner, William R. Yernberg, Steve Kral

Advanced Terra Testing (ATT)is a full-service geotechnical testing laboratory. It specializes in rock and soil mechanics and geosynthetic materials testing. ATT provides services to the global mining industry. The company has performed more than 1,000 projects for more than 300 commercial and government clients. Services include coal pillar design testing, leach pad material and performance testing, tailings pile consolidation testing and closure and remediation services. Rock and soil mechanics tests include unconfined and triaxial strength, shear and tensile strength, permeability, index testing, consolidation, liquifaction potential, elastic moduli determinations, heap height versus percolation rate, long-term batch testing and dynamic loading tests.

Jan 1, 2003