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By B. W. Stunkard

Hibbing Taconite Company is located by the cities of Hibbing and chisholm near the center of the Mesabi Range, approximately 169 km (105 miles) from the Canadian Border. The plant site is equidistant from these two communities, about 6.4 km (4 miles) from each. A 169 km (105 mile) railroad connects us with the port of Superior, Wisconsin, where the pellet production is loaded into lake carriers for lower lakes destinations. Immediately to the south of the mine area is the world famous Hull- Rust-Mahoning Mine which produced more than 700 000 000 million tons of red ore between the years 1893 and 1973.

Jan 1, 1979

By M. S. Safarzadeh, V. Agarwal

"The solvent extraction of cerium(III) and samarium(III) from mixed solutions of all rare earth elements (REEs) except promethium using PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), an acidic extractant, was investigated. The effects of aqueous equilibrium pH, various acids (sulfuric acid (H2 SO4 ), hydrochloric acid (HCl) and nitric acid (HNO3 )), initial metal ion concentration and extractant concentration on the solvent extraction of Ce(III) and Sm(III) were systematically studied. From the experimental results, HNO3 and HCl were found to be the preferred aqueous media for the solvent extraction of both Sm(III) and Ce(III). The most promising experimental conditions of pH, PC88A concentration and metal ion concentration were identified for the extraction of Ce(III) and Sm(III). Separation results showed that H2 SO4 at pH 2 provided the best separation between Sm(III) and Ce(III). IntroductionIn recent years, demand for rare earth elements (REEs) has increased significantly because of their many commercial applications. REEs have especially important high-tech applications owing to their unique physical and chemical properties, and they are used in a wide range of areas such as catalysts, ceramics, magnets, lasers, glass, neutron absorption and alloys. As REEs have very similar physicochemical properties, their separation and purification from each other is challenging and gaining significant interest. Samarium (Sm) and cerium (Ce) are found in different REE minerals, including bastnäsite ((Ce,La,Nd(CO3)F), xenotime (YPO4) and monazite ((Ce,La,Nd,Th)PO4) at major production sites in the United States and China, as listed in Table 1 (Bleiwas and Gambogi, 2013). The most common acidic organophosphorous extractants used for REEs extraction and separation are DEHPA (di-(2-ethylhexyl)phosphoric acid), PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) and Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) (Sarangi, Reddy and Das, 1999; Surampally et al., 2012; Tian, Jia and Liao, 2013). Out of these extractants, PC88A is known for providing higher separation factors (Acharya, Mishra and Misra, 2015). El-Hefny et al. (2010) investigated the kinetics of the solvent extraction of Sm from chloride media using sodium salt of Cyanex 272 and reported the extracted species to be Sm(OH)A2•2HA. Lee et al. (2005) investigated the solvent extraction of Sm(III) with PC88A and saponified PC88A from chloride solutions and found the stoichiometry of the extraction reactions to be 1.5 with PC88A and 3 with saponified PC88A."

Jan 1, 2017

By William C. Howe

This paper describes the technical status of the atmospheric pressure fluidized bed combustion (AFBC) process for utility steam generation. Major areas where AFBC development work is needed are discussed. Various approaches to solving these key issues are identified and the ongoing research and development programs addressing the key development areas are described. Other significant programs pertaining to the development of AFBC for utility steam generation are also discussed and needs for future work identified.

Jan 1, 1978

By Matthew Deutsch

A common casualty of modern openpit mine optimization is the assurance that the resulting design is actually achievable. Optimized mine plans that consider value and a bare minimum of precedence constraints do not, in general, translate into practical, operational mine designs that can be used in the field. Ultimate pits may come to a sharp point at the bottom. Schedules may require taking small parcels of material from many disparate areas of the pit in a single period, and grade control polygons may be ragged, narrow and not minable with realistic equipment. In this paper, these three fundamental openpit mine optimization problems are addressed by encoding them as maximum satisfiability problems. Maximum satisfiability provides a useful framework for problems that are nonlinear and may guarantee the optimality that metaheuristics cannot.

By VIVEK KASHYAP, Evody Tshijik Karumb, PATRICK TAYLOR

The partial reduction of zinc ferrite to zinc oxide and iron (II, III) oxide can enhance the leaching rate of zinc. Zinc ferrite has often been found as a major component of zinc residues and electric arc furnace dust. The Waelz process is an existing process for zinc ferrite processing, which requires a temperature of more than about 1200 °C to produce Waelz oxide containing ZnO. Since zinc residues have been deemed as a potential way for the extraction of zinc and other critical metals, it is important to analyze the reaction kinetics in the temperature range of interest. This manuscript discusses the chemical kinetics of zinc ferrite reduction by hydrogen gas. Several researchers studied the reduction of zinc ferrite with CO; however, unlike CO, the use of H2 gas as a reductant allows partial reduction of zinc ferrite even at low-temperature range (400–600 °C). Thermogravimetric analyses (TGA) experiments were performed in the temperature range of 300–700 °C with 10% and 30% H2, and the data obtained was analyzed using the isoconversional method of kinetic analyses. The standard models used for isoconversional kinetic analysis were chosen from literature and experimental data were fitted to determine the controlling mechanism and calculation of kinetic parameters of reduction of zinc ferrite. The rate of reaction was found to be increasing with an increase in temperature and partial pressure of H2 gas. The reaction could be divided into three stages, where reaction interface contraction was found to be the controlling mechanism at the initial stage of reaction. As the reaction proceeds, product layer thickness increases, and thus, diffusion was found to be the controlling mechanism. Roasting products obtained from TGA experiments were also characterized using a scanning electron microscope (SEM) to verify critical morphological details.

Jul 26, 2022

By R. Chandramohan, Landon Jackson, C. Meinke

Understanding constraints within the raw battery material supply chain is essential for making informed decisions that will ensure the battery industry’s future success. The primary limiting factor for long-term mass production of batteries is mineral extraction constraints. These constraints are highlighted in a first fill analysis which showed significant risks if lithium-ion batteries are used to fully support vehicle electrification and intermittent energy storage. Nickel, lithium, cobalt and graphite reserves risk 100 percent depletion with significant consumption of known resources. Furthermore, more than 700 new critical mineral mines will need to be developed to meet the required production rates for decarbonization by 2050. Demand for critical minerals will outpace mine development timelines even as improvements are made to battery energy density and compositions. Governments and the private sector need to align themselves on decarbonization goals to establish cooperative agreements on the critical mineral supply chain by reducing the barriers to entry and increasing exploration efforts. Additional measures must also be taken to reduce the demand for critical minerals. Policy such as incentivizing public transportation and biking infrastructure can be exploited to drastically reduce the mineral demand placed on the mining industry.

Feb 1, 2025

By SUMANT KUMAR SAMAL, BHAGIRATHA MISHRA, MANOJA KUMAR MOHANTY, SUBASH CHANDRA MISHRA

Steelmaking consumes the majority of chromium and manganese ferroalloys for purposes such as to impart various properties to steel. The quality of ore governs the process kinetics as well as the process economy of the ferroalloy industry. The present study demonstrates the thermal transformation behavior of chromite and manganese ores with varying compositions. Simultaneous thermal analysis (differential thermal analysis/thermogravimetry, DTA/TG) was conducted on these ore samples, where the transformation of mineral phases was correlated with the thermogram characteristics and quantified. Phase, microstructure and compositional analysis results of individual ores corroborated with thermal analysis are in good agreement. Chromite samples are ferruginous with goethite and gibbsite contents, whereas manganese ores vary in composition and also exhibit multiple and/or overlapping transformations.

By R. Sellaro, E. Sarver

It has long been understood that extended occupational exposures to respirable mine dusts can lead to chronic lung disease. In underground coal mines, coal workers pneumoconiosis (CWP) and silicosis are major concerns. While many efforts have been made with the aim of understanding the mass-based concentrations and silica contents of respirable dusts under a variety of mining conditions, little research has been completed in characterizing dust at the individual particle level (by composition, size and shape). This study employed scanning electron microscopy with energy dispersive x-ray (SEM-EDX) to analyze dust samples collected from an underground coal mine in Central Appalachia. The results indicated that particle characteristics can vary widely between locations, though many trends might be explained based on knowledge of mining conditions. A continuous personal dust monitor (CPDM) was also used during the collection of some samples to determine respirable dust concentrations, which were compared against estimated concentrations based on the particle-level analysis.

Jan 1, 2014

By J. M. Barker

New Mexico is the leading domestic producer of perlite, a hydrated volcanic glass that can be expanded thermally to form a white, very porous, lightweight material. The United States is the leading consumer and producer of perlite in the world (Pettifer 1981). New Mexico produced, at five mines (Fig. 1), about 86% of all domestic crude ore mined in 1984 (Meisinger, 1985). Perlite is mined in 6 other western states, ore is expanded in 33 states, and the expanded ore is consumed in all states (Meisinger, 1985). Gross value of domestic ore mined in 1984 was about $16,500,000 (FOB mine; Meisinger, 1985) with much value added by expansion and processing prior to sale to end users. In contrast to the ubiquitous nature of perlite products in the U.S. economy, facilities for testing perlite ore, expanded perlite, and perlite products are notably lacking on a commercial, cost-effective, or readily accessible basis. The New Mexico Bureau of Mines and Min¬eral Resources (NMBM&MR) established a perlite¬testing facility in 1984 to mitigate this lack and to further the mining of perlite in the state.

Jan 1, 1985

By FHATUWANI SENGANI

The understanding of yielding pillar behavior has been well documented in terms of pillar strength using numerical simulations and empirical formulas, but the understanding of how fracture propagates in a matured yielding pillar is not well established. A new empirical summation chart of fracture distribution along the matured yielding pillar is presented in this paper. The chart was developed using ground penetrating radar (GPR) supported by borescope observations, focusing on monitoring the distribution of extension fracture.

By A. Benchekroun

The phosphate mining industry is confronted everywhere in the world with financial difficulties and low prices which prohibit further investments and development of new mines even in regions with a comparative cost advantage (North America/ North Africa/ and Middle East). But old mines are being progressively exhausted/ and if no replacement mines come on stream in the near future/ we may soon find ourselves (around the year 2000) with a global annual production capacity of 160 million tonnes of marketable phosphate rock instead of the capacity of 200 million tonnes existing today. Unless prices improve/ phosphate rock/ a non-renewable resource and a vital commodity to world agriculture/ may turn to be in short supply to world fertilizer industry. Whatever the extent of recovery of fertilizer demand/ the expected decline of the production capacity during the 1990 I s is bound to cause the disappearance by the year 2000 of the important surplus characterizing today the supply/demand balance.

Jan 1, 1995

By J. Rostami, J. Brune, S. Slouka

Respirable dust poses long-term health issues to personnel working in mining and civil projects where mechanized mining and tunneling machines are used for hard rock excavation. Machines, such as longwall shearers, roadheaders, or continuous miners, use consumable picks to cut rock. However, rock dust is generated in the work environment each time the pick tip contacts the rock surface. Additionally, the generated dust can be reintroduced into the air further down in production, such as at transfer points. The purpose of this study is to characterize respirable dust particles generated at the pick tip at two stages of pick wear: new and moderately worn. Understanding dust characteristics in terms of concentration, size distribution, and particle shape throughout the life-cycle of the pick will provide a basis to mine and tunnel operators for changing out picks to mitigate dust generation at the source. This paper discusses the dust characteristics generated from preliminary full-scale cutting tests in a laboratory of an igneous rock block cut with conical picks at new and moderately worn levels of wear. The moderately worn pick generated a size distribution that favored smaller particle sizes compared to the new pick. The moderately worn pick also generated more overall dust, as the concentration level in mg/m3 was over double the amount of the new pick. Lastly, both picks generated particles that had similar aspect ratios and roundness measures.

May 18, 2022

By Kamran Esmaeili, MINGLIANG TANG

An understanding of the spatial and temporal variations of surface moisture content over a heap leach pad is essential for leaching production and to achieve a high ore recovery. The current leach-pad monitoring and data-collection practice remains highly labor intensive and exposes technical staff to cyanide solution, a hazardous material. To address these challenges, we propose using unmanned aerial vehicles (UAVs) equipped with thermal imaging sensors to remotely obtain image data with high temporal and spatial resolution for monitoring the surface moisture distribution over heap leach pads. A field study was conducted over a sprinkler-irrigated heap leach pad at El Gallo gold mine in Sinaloa, Mexico, and the acquired data were used to generate moisture distribution maps of the heap leach pad’s surface. The created moisture maps provide direct visualizations of surface moisture variation over the surveyed area. Such graphical results are effective tools for inspecting heap-leaching operations.

By SHANTAE LEE, ELAHEH TALEBI, Frank A. Drews, ROGERS W. PRATT

Fatigue is a relatively well-investigated topic in the surface transportation industry with a research focus on sleep deprivation and disruption. This paper examines fatigue in mining operations. While mine operators are using or currently introducing technology to monitor fatigue, there is little work that focuses on the operators’ experience of fatigue and the acceptance of fatigue-monitoring technology. Focus groups were conducted to investigate these topics. The results of this research suggest that current fatigue-monitoring systems lack validity, reliability and user acceptance. Overall, these results emphasize the importance of a socio-technical systems perspective to guide interventions aiming at improving miner health and safety.

By Isabel F. Barton, Christian A. Rathkopf, Mark D. Barton

Rhenium (Re) is one of the rarest elements on earth and is a designated critical element in the United States and European Union for its uses in superalloys. Unusually among critical elements, Re is produced entirely as a byproduct of molybdenite (MoS2) mining, as pure Re minerals are extremely rare. However, Re concentration in natural molybdenites varies from a few parts per trillion to tens of percent. There are few known consistent patterns and no firmly established reason for this variation, making it difficult to use molybdenite Re content as a proxy for metal grades, a vector to high grades, a clue to the geological and geochemical nature of the ore deposit, a guide to overall Re resources or for any other of the applications that have been suggested for it over time. 

By Sahendra Ram, Ashok Kumar, Rakesh Kumar, AMIT KUMAR SINGH, Dheeraj Kumar, Arun Kumar Singh, Rajendra Singh

This paper describes the successful mechanized extraction of coal pillars in 11 panels using the fish-tail method from 2010 to 2017 at Pinoura Mine in India. This method proved its potential of coal recovery with efficient strata control under weak roof due to faster rate of extraction in a single lift. Observations of strata and snook behavior during the field studies in different panels of the mine are included.

By T. McWaters

Miami Copper Company began a block-caving operation in 1911 using a gravity mill to separate copper minerals from the Pinal Schist host rock. The tailing was deposited by the upstream method using perimeter launders and spigot valves in six canyons adjacent to the mill until 1932. In 1928 the larger and more distant Solitude tailing pile was developed which by 1932 was receiving all tailing except for upsets. In 1925 Miami Copper converted its gravity mill to flotation which began to produce higher sulfide copper recoveries.

Jan 1, 1990

By Robert L. Llewellyn

The Wharton No. 2 Mine of Eastern Gas and Fuel Associates is located about 60 miles south of Charleston, West Virginia in Boone County. Daily production is 6,000 T.P.D. on a two-shift basis. The Hernshaw Seam is mined by conventional equipment with one continuous miner in areas where conditions are suitable. The plant is on Cow Creek .Branch of Pond Fork, which in turn flows into the Little Coal River at Madison, West Virginia. When the mine was opened in 1948, plans were developed to build a dual Baum jig plant complete with mechanical and thermal drying, and because full production would not be reached for several years, it was decided to install only one Baum jig setup although the complete structure was erected. This phase of the plant was placed into operation early in 1949, The rated capacity was about 300 T.P.H. of 5" x 0 raw feed to the jig. Being a drift mine, the 10-ton mine cars are dumped at the Headhouse, crushed to 8" in a double roll crusher, conveyed 780 feet downhill to the picking .house where the +5" slate is removed by pickers. All coal is crushed to 5" and 5" x 0 is conveyed 150 feet to the cleaning plant. Further describing the plant growth, the second jig setup was installed in 1954 to clean the increased production. During this operating period, exhaustive tests had ,been run on the plant bleed which was an overflow from the large sludge tank located inside the plant, When the second jig addition was undertaken, 5-14' diameter and 12-8" diameter cyclones with a 9-disc filter were installed for the solids recovery and water clarification system, However, the circuit was not closed and a bleed of part of the overflows from the 8" diameter cyclones was still necessary, To comply with the State Water Commission regulations on stream pollution abatement, four pumps in series were installed to discharge the waste water behind the refuse pile.

Jan 1, 1959

By M. S. Moats, A. Luyima, W. Cui

"Organic smoothing additives are used to produce dense, thick, high-quality cathodes in copper electrowinning. Glue had been used traditionally and is still used in operations that do not employ solvent extraction to produce the electrowinning electrolyte. With the advent of solvent extraction–electrowinning, guar started to be used and remained in use for many years as it does not affect the phase disengagement in solvent extraction. Recently, however, guar has been replaced by less-expensive saccharide- and polyacrylamide-based additives. This paper is the first of a series of four papers that examine saccharides and polyacrylamides as new additives for copper electrowinning. A review of previous research related to copper electrowinning additives is presented here, along with a selected review of additives in other copper electrodeposition systems.IntroductionThe recovery of copper from solution by electrowinning was first practiced in the early 1900s, but it was the combination of solvent extraction with electrowinning (SX-EW) in March 1968 at the Ranchers Bluebird Mine (Kordosky, 1992) that changed the landscape for the electrowinning process. Most copper electrowinning capacity is now associated with solvent extraction, though some copper is still won directly from leach solutions (Robinson et al., 2013). The ability to produce high-purity copper cathodes from SX-EW has taken the continued improvement of SX-EW technology over the past more than 40 years.One of the technologies that has seen improvement is that of the organic smoothing agents used during the electrodeposition of copper in the tankhouse. These organic additives are added to the acidic copper sulfate electrolyte during electrowinning to improve the smoothness, brightness and density of the copper cathodes. The organic additives that are presently in use are different from those used in 1999 (Jenkins et al., 1999). Over the past decade, many tankhouses have replaced the use of guar-based organic additives with those derived from other saccharides. Until now, there has been no comprehensive publication in the open literature on the behavior of these additives during copper electrowinning."

Jan 1, 2016

My first regular job nearly fell through. My parents were spending the summer in California and I joined them at Lake Tahoe where we were guests at the lovely summer home of the Reids of Belmont. The time went quickly but I was eager to start work so I left for Bisbee a few days earlier than I had arranged. This was lucky, as just after I left a letter came from Gene Whitely, chief engineer of Calumet and Arizona, saying that because of the depressed copper industry there would be no job. I reached Bisbee on a Saturday morning, a day or two before my 23rd birthday, July 27, 1907. The brown plastei four-story Copper Queen Hotel was only a few steps from the station where the branch railway ended. I rented the cheapest room on the top floor and, of course, there was no elevator. I soon learned how to walk up the mile of switching tracks to the Calumet and Arizona office at the Irish Mag mine. I was horrified when Whitely told me about his letter telling me not to come, but since I had not received it he relented and said I could work for a short time anyhow. I was to start at 7:30 the next Monday morning, "holding the ignorant end of the tape”-in other words being surveyor's assistant, at $100 a month. Hours were from 7:30 to 5: 00, seven days a week. I spent Sunday walking around the town. I rented a room at the Royal Lodging House, which was cheaper than the hotel. It smelled strongly of carbolic acid but that meant no bugs. Compared with Cobalt or Cripple Creek, Bisbee didn't seem unattractive. The main street, with one or two-storied stores and saloons, followed the bottom of the canyon with high steep hills on both sides. My lodging house was on a rock in a narrow spot in the canyon, discouragingly called Tombstone Canyon. Chihuahua Hill, opposite the

Jan 1, 1976