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By J. Astier

The idea of using only one strand for both sintering and cooling of the sinter is not new. In 1952, in the U.S.A. a sintering plant was built at Benson Mine (Star Lake, N.Y.), including : - 68 m2 or 735 sqft (8 wind boxes) for sintering, - 22 m2 or 237 sqft (3 wind boxes) for cooling. In the USSR, a large number of machines have been built allowing for cooling of the sinter on the strand, especially the 4 m (about 13 ft) machines, with : 252 m2 sintering grate area 60 m2 cooling grate area 312 m2 total grate area. However, such ventures did not prove very successful, and the IRSID embarked many years ago on a research program to discover : - what are the problems associated with cooling on a sintering strand ; - what are the possible solutions for industrial plants.

Jan 1, 1974

By Felipe Calizaya, Sekhar Bhattacharyya

Mechanized underground mines suffer from noise overexposure. Noise levels are often above the Permissible Exposure Limit (PEL) where underground fans are used. Sound levels in active workings can reach up to 121 A-weighted decibels (dB(A)), especially when fans are not equipped with silencers. Use of silencers seldom ensures PEL. Overexposure of noise induces permanent hearing loss among mine workers. A NIOSH-funded research project and field studies at six coal and non-coal mines revalidated the findings. The University of Utah undertook laboratory studies to reduce fan noise at the source. A new silencer prototype with varying noise dampening material was designed and tested. The silencer and associated extension can be repacked with different dampening materials. The silencer and the extension were used in various configurations. Attempts were also made to simulate field conditions. The tests demonstrated a maximum sound level attenuation of about 14 dB(A) at the fan discharge. A properly designed silencer offers lesser resistance and thereby better fan performance and lower energy cost. The re-packable silencer is more likely to be maintained properly. Lowering of noise level happens in audible frequencies (4000 to 8000 Hz) which are important in A-weighting.

By Ana E. Bohé, Georgina De Micco, Juan P. Gaviría, FEDERICO J. POMIRO, Gastón G. Fouga

Chlorination and carbochlorination processes have industrial applications in metallurgical activity for extraction and purification of uncommon metals such as rare earth elements (REE). This study reviews the chlorination and carbochlorination reactions of light REE (LREE) oxides with chlorine considering the thermodynamic, stoichiometric, and kinetic aspects of the reactions. Lanthanides between lanthanum to gadolinium were considered as LREE, in agreement with previous literature, and the results were detailed in this review. LREE were analyzed taking into account their oxidation states and were divided into three groups accordingly. The results presented show that, although the LREE are chemically similar, their behaviors during the reactions with Cl2 and Cl2–C, and the different LREE-O–Cl compounds formed, have particularities. It was observed that gadolinium, in both thermodynamic calculations and experimental results, presents some differences, and it can be considered intermediate between light and heavy REE; i.e., reactions between LREE2O3 and Cl2(g) begin at approximately 250 °C, except for Gd2O3 that begins at 327 °C. The present work will contribute to a better understanding of the chemistry of LREE oxides and Cl2 under different conditions and the products obtained in the LREE–O––Cl2(g) and LREE–O–C–Cl2(g) systems.

Oct 15, 2021

By W. David Tyler

Any mining or engineering-construction excavation that extends below the water table must be dewatered. In many situations, the ground is of low permeability or the workings extend only a short distance below the water table. So water removal can be handled easily and economically by using mobile centrifugal pumps. However, there is an increasing number of mines that have a continuous high flow of water into the workings. Controlling this flow can significantly increase the cost of ore production. Successful implementation of any major dewatering scheme will ultimately rely on a clear understanding of the local geology. This understanding is necessary before an interpretation of ground water conditions can be made. It will dictate which dewatering methods are feasible. Once the geology and the ground water system are known, the scope and timing of the dewatering measures can be varied with the mine plan. Ground water modeling can assist in optimizing the dewatering system, though the precise objective of each model should be clearly defined. Production wells must be sited and drilled so that individual well efficiencies are high. Any lost efficiencies will translate into higher operating costs. Each well must be designed for maximum long-term control of the water table, and pumps sized to operate under continually changing heads. Finally, the investment in each production well must be protected during the mining process.

Jan 1, 1991

By John C. Kleiber

From time to time since the initial installation of an experimental flotation section in 1940 (reference A), Permanente Cement Company has made efforts to beneficiate the low-grade limestone fraction which occurs in its deposit at Permanente, California, The encouraging results outlined in this paper are the result of Permanente's latest effort. This paper discusses the factors governing the selection of the flowsheet with particular reference to marketability of the sand tailing by-product. The process flow is outlined in detail, and operating statistics of the plant are presented. Finally, the problems encountered in the operation of Permanente's beneficiation plant are discussed as well as solutions sought and found.

Jan 1, 1964

By D. S. Yantek, L. A. Alcorn, M. J. Lowe, H. E. Camargo

U.S. National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the U.S. Mine Safety and Health Administration permissible exposure level of 90 dB(A). Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Office of Mine Safety and Health Research laboratory in Pittsburgh. The results show that the entire screen contributes to noise below 1 kHz, and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise in this range from 1-10 kHz. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam™ panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2011

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By Yong Pan, Srivatsan Jayaraman Sridharan, Purushotham Tukkaraja

Block cave mining method poses unique ventilation challenges compared to other underground metal mining methods. This research study focuses on assessing the airflow behavior in regulated airflow distribution systems by developing a 1:100 scaled block cave experimental model and a numerical model. This study also investigated gas flow behavior under various airflow conditions. Based on our findings, we observed that reduction in particle size and porosity of caved materials, decrease in cave footprint, and closure of undercut drifts would increase cave airflow resistance. The increased airflow is found beneficial for gas dilution regardless of its source locations, while the regulated airflow distribution system might deteriorate gas dilution situation when the source is located in the extraction drifts.

May 12, 2022

By Don L. Deardorff

The Deserado Mine and transportation system is the fuel supply portion of the Bonanza Power Plant project. Deserado Mine con¬sists of an underground mine with a capacity of 1,224,700 tonnes (1,350,000 tons) of clean coal per year, a 649 tonne (715 tons) per hour closed water circuit jig type preparation plant, a 5.6-kilometer (3 ½ -mile) overland conveyor with covered slot storage, a unit train rail load-out and 59.5 kilometers (37 miles) of totally independ¬ent, captive electrified railroad. Planning and exploration started in March of 1978. Construction of all facilities was completed in April of 1984, approximately six years after initial planning was commenced. This paper will discuss exploration, environmental permitting, mine planning, engineering and construction of the Deserado Mine project.

Jan 1, 1984

By Saman Khaleghparast, Naj Aziz, Jan Nemcik, Guanyu Yang

"More than 25 years of uninterrupted research on ground support technology for underground mines has been undertaken at the University of Wollongong. This research has resulted in significant findings on tendon characteristics and strength properties. The paper focuses on the development of the fourth generation of cylindrically shaped shear test apparatus for assessing tendon performance in shear. This shear apparatus is known as the MK-IV Double Shear Box or Naj Aziz Double Shear Box (NADSB), and is based on the experience gained from the development of previous versions of rectangular double shear boxes. The new NADSB is circular in shape and is fitted with a truss system, which permits friction free shear testing of tendons across joint planes. A series of double shear tests were carried out on a number of cable bolts commonly used in Australian mines, both plain and indented wires, under varied pretension loads. The results were compared with similar test results using rectangular shaped double shear apparatus, with and without friction across joint faces. The significance of wire surface roughness and increased initial pretension loads are discussed and conclusions made, suggesting that indented wires are inferior in shear compared with plain cable bolts. The general test procedure of the NADSB is described and different concrete reinforcement techniques are reported. The influence of external and internal confinement of the concrete medium blocks in a circular double shear box contributed to consistent test results with a minimum of lateral and axial cracks occurring in the host medium.INTRODUCTIONThe use of long tendon ground support elements (cable bolts) is now a common practice in modern underground coal mines, hard rock mines, tunnels and other underground structures. Due to their material properties cable bolts contribute significantly to the overall ground reinforcement provided by a support system. Cable properties in tension and shear are in many cases vital to maintaining a safe and productive underground environment. Accordingly, tension and shear properties must be assessed accurately using both valid and reliable methods.Load transfer property testing of tendons has been studied over several decades with much of the early research focused on the pull and shear testing of solid rock bolts and hollow bolts (like Swellex and split set tube bolts), as these elements were used extensively at this time. It was not until the 1970’s that the use of cables for ground reinforcement developed, and as such highlighted the need to extend load transfer property testing to include shear strength of cable bolts. Initially, the discarded hoisting ropes were used for ground support in metal mines, particularly in stopping wall support and then late in 1980’s cable tendons began to use in coal mines."

Jan 1, 2019

By Francesco Chiappalone, Daniele Nebbia, Lance Waddell, Greg Colzani

As part of the 3RPORT Project, a 5-mile tunnel is being excavated underneath the three rivers of Fort Wayne using a 19-foot diameter Slurry Tunnel Boring Machine. The groundwater pressure at the tunnel axis ranges from 4.5 to 5.3 bar. The rock mass hydraulic conductivity is very high with water inflows up to 10,000gpm imposing significant challenges to the project. After excavating 1,550-feet of the TBM tunnel, major leaks between the tailskin and the segmental lining were observed, indicating the potential deterioration of the tailskin brushes and the need for inspection and eventual replacement. The first part of the paper describes the planning of the intervention, including the design of the polyurethane grouting campaign, the procedures developed for the execution and the controls established during construction to timely assess the presence of potential hazards. The second part of the paper focuses on the experience gained during execution and lesson learned to prevent future occurrences of this nature.

Jun 13, 2021

By Luis de la Pe[n]a Porth

The present process refers to a method for efficiently obtaining high purity metallic copper from copper ammonium sulfite. Essentially, this process consists of submitting the copper ammonium sulfite to the action of heat and pressure with the object of obtaining by the decomposition of it, metallic copper, ammonium sulfate, sulfur dioxide, and sulfuric acid.

Jan 1, 1974

By Jung-Joo Kim, Jong-Uk Kim, Turab H. Jafri, Han-Kyu Yoo

"INTRODUCTION Steel sets such as H-type and lattice girders are often installed in the tunnels before the hardening of shotcrete to ensure the stability of conventional tunnels in soft ground conditions. In practice, while designing the tunnels with the help of numerical analysis, steel sets are generally considered only as temporary support elements. Only a few studies propose the direct application of composite support in the tunnel design, based on large-scale experiments and numerical analysis. In order to assess the structural performance of the composite support consisting of shotcrete and steel sets, large-scale experiments were performed on two types of arch-shaped specimens by applying the combined effects of axial forces and bending moments. Based on the experimental results, numerical analysis was performed to assess the application of composite support in tunnel design. The crown settlement, axial forces, bending moments, and load distribution in the composite support were analyzed in the light of different structural patterns. LARGE-SCALE EXPERIMENTS USING COMPOSITE SUPPORT Preparation and Procedure of the Experiments The preparation setup as well as the organized procedure of the large-scale experiments using composite support is shown in Figure 1. An appropriate geometry of the specimens was selected by considering the standard cross-section of a two-lane highway tunnel in South Korea. Under the loading conditions meant to develop the axial forces and bending moments simultaneously, arch-shaped specimens were assembled with the ends of the specimens subtending a 60° arc angle at the center of the arc circle as shown in Figure 2. The fabrication of six specimens was completed in two groups based on the dimensions of steel sets, with the first group of three specimens being reinforced by H100 (No.1, No.2, No.3) and the other three by H125 (No.4, No.5, No.6). In order to reduce the voids on the boundary of the shotcrete and steel sets, concrete was casted over the steel sets instead of using shotcrete. The specimens were designed to incorporate the uniaxial compressive strength of 21 MPa. Shear keys and steel plates were installed at the ends of the specimens, so that shear failure could be avoided at the ends and the specimens could also be protected from detachment at the fixation. Translational and rotational movements at the ends of specimens were fixed."

Jan 1, 2016

By Jogeshwara Sahu, Sapan Kumar Kandi, SANDEEP KUMAR JENA, Sachida Nanda Sahu, Sarada Prasad Das

The present article reports the recovery of potassium from mica scrap using carbide lime waste and NaCl. The acid leaching of mica [4 M H2SO4 at 90 °C] can recover a maximum of 25% potassium. However, in the chlorination roasting (with CLW and NaCl) water leaching process, it was possible to recover potassium to the tune of 94% [900 °C, 50 min roasting; mica:CLW:NaCl 1:0.75:1]. The formation of water-soluble phase like sylvite (KCl) and water-insoluble phases like anorthite ( CaAl2Si2O8) and nepheline ( NaAlSiO4) confirms the complete breakdown of the mica crystal structure. The extraction mechanism proceeds with the formation of a transition state followed by the release of potassium as KCl. The characterisation studies using ICP-OES, XRD, FTIR and FESEM support the proposed extraction mechanism. The salt produced by the evaporation of roast-leached liquor confirms the presence of sylvite and halite only, which can be separated to get the fertiliser grade KCl.

Sep 29, 2021

By G. A. Parkison

The sequential copper analysis method is a particularly useful technique to semi-quantitatively define the geologic, mineralogic, and metallurgical types and zonations commonly associated with porphyry-type copper deposits. The method is based on the partial dissolution behavior displayed by the prevalent copper minerals malachite, chrysocolla, chalcocite, and chalcopyrite to solutions containing sulfuric acid and sodium cyanide. Results from sequential analyses of the sample and analytical residue using sulfuric acid followed by sodium cyanide and then aqua regia solutions when compared with conventional total copper analyses can determine the amounts of leachable oxide minerals, leachable secondary sulfide minerals, and primary copper minerals, respectively. Sequential assay analytical results and interpretation are presented for copper deposits in Chile, Mexico, and the United States.

Jan 1, 1995

By Taghi Sharizadeh, MAURICE SUNKPAL, ELAHEH TALEBI, PEDRAM ROGHANCHI

Excessive heat exposure is among the health and safety hazards that have adverse effects on the mine workers. The very nature of the underground climate makes it a convenient avenue for heat generation and accumulation from several heat sources including autocompression, equipment, and heat from strata. This study investigated the effects of clothing insulation and acclimation on the thermal comfort ofmineworkers who are exposed to heat in underground working environments. Several clothing ensembles have been considered to analyze the effect of the thermal resistance of clothing on the thermal comfort of workers. To investigate the impact of the clothing insulation, the thermal comfort limit of an underground miner was calculated in the form of maximum allowable exposure time for an 8-h shift. Parametric analyses were subsequently performed using an already developed thermal comfort model using MATLAB software. The results demonstrate that clothing insulation has a significant effect on the thermal comfort of mine workers. Increase in the clothing insulation decreases the maximum allowable exposure time of mine workers. This is especially true for the new and non-acclimated workers. Since acclimatized workers can tolerate a higher level of the dehydration and are capable of losing more water by sweat per shift, the maximum allowable exposure time for the acclimated workers are higher than non-acclimated workers. These analyses have shown that acclimated workers can have more continuous work per shift compared with non-acclimated workers. For example, in an environmental condition with clothing that a nonacclimated worker cannot work more than 5 h, an acclimated worker can work a full 8-h shift.

Jun 29, 2020

By Karin Bäppler

Hydropower produces almost two-thirds of the world’s renewable electricity generation and delivers a major contribution on the ambition of the Paris Agreement and Sustainable Development Goals (SDG) with a range of benefits to society and environment. These include clean and flexible generation and storage in addition to reduced dependence on fossil fuels and avoidance of pollutants. The Limberg III PSP is one of the European projects that addresses the implementation of the UN SDGs. The challenge of the project is the construction of a 770 m long pressure shaft to be excavated with a TBM at an inclination of 42°.

Jun 13, 2023

By Lana Alagha, Fardis Nakhaei, Jose L. Corchado-Albelo

Tellurium (Te), a critical mineral for solar energy technologies, faces supply risk challenges that drive the development of diversified and robust production routes. This research focused on improving Te enrichment from copper tailings (CT) produced from copper porphyry (CP) ores processing, addressing the loss of ~90% of Te minerals to tailings in the flotation process of CP ores. Gravity separation and froth flotation processes were used as possible enrichment routes of Te-bearing minerals (i.e., pyrite) in CT. In the froth flotation process, synergistic combinations of reagents were tested to achieve an acceptable enrichment ratio of Te minerals. Comprehensive characterization analyses showed significant Te enrichment in the flotation concentrates. Tellurium was recovered at 90%, while the grade of Te in the concentrates was 1.4 ppm using a xanthate collector and glycol frother compared to <0.5 ppm in the flotation feed. Findings showed that Te-minerals’ enrichment was also feasible in CT using the proposed combined concentrations routes (i.e., gravity separation followed by froth flotation) by looking at Fe, Cu, and S enrichment. This study also highlighted the importance of understanding the deportment of Te minerals in different process streams to develop and optimize efficient enrichment practices.

Feb 1, 2024

Arizona copper mines produced nearly 67% of the nation?s copper in 2000, according to a report released by the Arizona Mining Association (AMA). This was a slightly larger share than in 2000 despite large reductions by one major copper producer and production cutbacks at several other facilities. In 1999, Arizona mines produced 64% of the nation?s copper. The report was prepared by economist George F. Leaming of the Western Economic Analysis Center in Marana, AZ. It also showed the copper industry had a $4.6-billion impact on the Arizona economy in 2000, a 26%decline from 1999. This is the lowest financial impact since 1973 and less than half the record reached in 1981of $9.6 billion. The decline is primarily due to a sustained low copper price and a slow-down in the US economy. The mining industry?s impact included combined direct and indirect contributions of $1.283 billion in personal income for Arizona residents, the equivalent of 43,000jobs. More than 5,000 of those jobs were in state and local government and more than 18,000 were in trade and ser-vice businesses. The copper industry directly employed fewer than 8,000 people statewide in 2000. This was down about 23% from 1999.

Jan 1, 2001

By Donald L. Everhart

Economic geologists faced with the task of evaluating phosphate rock deposits find it necessary to deal with a unique and a lengthy list of geologic, chemical, and economic factors before they can determine whether the deposit does, or does not, constitute "ore". The underlying fact is that phosphate rock concentrate sells at a price per ton that is among the lowest for all mineral commodities. A recent going price for a standard grade (i.e. 72% BPL) phosphate rock concentrate F.O.B. Tampa is $6.00 per long ton. This compares with sand and gravel&apos;s price of about $5.00 and $8.00, respectively, per ton. In the case of many, if not the great majority of mineral deposits, the evaluating geologist needs to concern himself principally with the fundamental and classic considerations of tonnage and grade. Barring some very unusual metallurgical problem any geologist that finds say 50 million tons of 1% copper rock, or substantial tonnages of 0.7% U308 sandstone, pretty well knows he has an ore body! Certainly the evaluation of phosphate rock starts with tonnage and grade. Any rock with less than about 10% P205 in the ground is generally ruled out as ore, on the basis of grade alone. Since nearly all phosphate rock operations must be of the large-tonnage, low-unit-value type, the tonnage of new reserves, to be considered as "ore", ought to be in the 100-million + class. But having outlined&apos; a deposit of phosphate rock having acceptable

Jan 1, 1971