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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

By H. R. Bullis

Lupin is located on the shores of Contwoyto Lake at lat. 65° 48&apos;N, Long. 111° 15&apos;W and lies about 80 kilometers south of the Arctic Circle. Since start up in 1982 the mine has produced over 2.15 million ounces of gold from 6.66 million tonnes of ore grading 10.63 gm/tonne. Total remaining reserves at 1993 year end were 5.1 million tonnes at a grade of 9.11 gm/tonne (1.65 million ounces). This is sufficient for 7 -8 years at the present annual production rate of about 200,000 ounces. The Centre and West Zones of the deposit are open to depth. The deposit is in an Archean metaturbidite sequence of the Contwoyto Formation, which has been mapped as part of the Yellowknife Supergroup of supracrustal metasedimentary and metavolcanic rocks making up part of the Slave Geologic Province. These rocks have been subjected to regionar and contact metamorphism and to several phases of deformation. Six stages of Archean plutonism have been identified and all Archean rocks have been cut by Proterozoic diabase dyke swarms. Gold mineralization in the Lupin deposit is commonly fine grained and associated with pyrrhotite and arsenopyrite in amphibolitic banded iron formation. The gold-bearing portions of the host iron formations are characterized by the presence of multiple quartz veins and the pervasive replacement of grunerite by hornblende. In sparsely mineralized portions of the host iron formation, zoning of sulfides about quartz veins is clearly seen with the arsenopyrite halo being more restricted around the veins than the pyrrhotite halo. In well mineralized portions, quartz vein densities approach one vein per metre along strike. In these areas pyrrhotite distribution in the iron formation is more pervasive and the rock takes on the appearance of a banded sulphide rock.

Jan 1, 1995

By Peter Cammack

Where raw coal from a mine is treated in dense medium separators ash in the washed product is generally very consistent, provided control of the medium suspension is maintained at a given specific gravity. When, however, the washing process is a Baum jig or other similar apparatus, making a separation at rather arbitrary gravities, the control of the product ash is less accurate, particularly in those cases where the design capacity of the washbox is exceeded by the load of high ash fines. In either of these cases an instantaneous measurement of ash while not essential would be desirable, to check the quality of the washed product and provide operator or management with instantaneous warning of changes in ash. Nearly 60% of all British coal mined goes for electricity generation, to burn at 17% ash, and since the overall average ash content of raw coal as mined is about 30% and varies within a range of 18 ? 40%, incombustible material has to be removed. The ash specification could be met either by total washing, or by washing part and blending the clean coal produced with the remaining untreated coal. Some plants use a straight tonnage split, but generally speaking in Britain it has been found more economical to screen and wash the oversize only. In either case for effective quality control in blending an instantaneous determination of the ash content of the product as it is made has been found essential, since standard ash determination by pyrolysis methods is lengthy and provides information too late to be used in the control of plants blending at the rate of 1000 ton/h.

Jan 1, 1976

By David Beck, Eko Wibowo, Hendri Silaen, Andres Sugiyanto, Karl Llewelyn

PT Freeport Indonesia’s Deep Mill Level Zone mine is one of the deepest block cave mines in the world and is in mountainous terrain in West Papua, Indonesia. The mineralization is hosted in a skarn deposit in a structural setting that is complex at the footprint, mine and regional scale. Large seismic events and significant episodes of rapid rock mass deformation are potentially critical geotechnical risks during this ramp-up stage of mining. Understanding the interaction between stress, strain, rock mass strength and geological structures is essential to minimize the hazard and engineer control measures to help ensure the safety of the employees while achieving production targets. This paper discusses how the seismicity and excavation damage have been shaped by the interactions between the mine and geological features, and how this affects strategic mining decisions. Additionally, the paper presents a summary of the mitigation measures used for mining the DMLZ in the safest and most productive way. These include improvements to geotechnical characterization of rock mass and structure, dynamic ground support designs, production scheduling for desirable cave propagation and a seismic monitoring system with re-entry protocols.

Apr 26, 2022

By A. G. Fonseca

The effects of coal cleaning, coal combustion and flue gas particulate removal systems on the partitioning of 12 trace elements were investigated. This study was prepared to help document the fate of trace elements in modern coal preparation plants and coal-fired utility boilers. The coal cleaning data were obtained from several coal preparation plant operations. The CONSOL 1. 5 MM Btu/hr pilot combustion and electrostatic precipitator (particulate removal system) test facility was used to develop the combustion systems data. A comparison with the very limited amount of published data from utility boilers is presented.

Jan 1, 1993

By B. G. Kelley

The MIDREX® Direct Reduction Process was developed during the 1960s by the Midland-Ross Corporation, which had pioneered shaft furnace technology and stoichiometric gas reforming for use in processing minerals. In 1969, the first MIDREX® Direct Reduction Plant was built in Portland, OR. Since then, 49 additional modules have been sold in 18 countries. For the last ten years, over 60 percent of the world&apos;s direct reduced iron has been produced in MIDREX Plants. During the quarter century since commercialization, many technical improvements have been made, including larger shaft furnaces, in-situ reforming, greater heat recovery, improved catalysts, and hot briquetting. Midrex continues to enhance the technology in the areas of economy-of-scale, energy efficiency, alternate fuels, and raw material flexibility.

Jan 1, 1998

By J. Y. Lee, J. Kang

"A selective chlorination process using cuprous chloride (CuCl) was investigated for producing high-grade chalcocite (Cu2S) from chalcopyrite (CuFeS2) feed. The chalcopyrite feed was reacted with CuCl in the presence or absence of sulfur (S) at temperatures between 900 and 1,100 K for five hours under an argon gas atmosphere. The experimental results indicate that iron (Fe) was selectively removed from the chalcopyrite feed as ferrous chloride (FeCl2) at 1,100K and the mass percentage of Fe thus decreased from 31.5 percent in the feed to less than 0.05 percent in the residue, under certain conditions. As a result, high-grade Cu2S was obtained from chalcopyrite in a single step. This new selective chlorination of chalcopyrite using CuCl as a chlorinating agent is therefore feasible for producing high-grade Cu2S.IntroductionCurrently, blister copper (Cu) is commercially produced from sulfide ores by pyrometallurgical methods. These methods entail matte smelting and converting, with the removal of iron (Fe) and sulfur (S) as slag — mainly Fe2SiO4 — and sulfur dioxide (SO2) gas, respectively.In the pyrometallurgical method, as shown in Fig. 1 (Schlesinger et al., 2011), Fe is removed through two steps at high temperatures of around 1,500 K to reduce the loss of Cu during slag formation. However, the slag still contains 1 to 8 percent Cu. Therefore, Cu in the slag is recovered by slag treatment processes, after which the concentration of Cu in the slag decreases to around 0.4 to 1.3 percent. Although Cu is recovered, the slag that had undergone the treatment processes is difficult to use as a feedstock for ironmaking owing to the small amount of Cu remaining in the slag (Schlesinger et al., 2011).In addition, large amounts of SO2 gas are generated by the oxidation of S in the current Cu production process. The SO2 gas generated is captured and used to produce sulfuric acid (H2SO4). However, despite the development of SO2 gas-capture technologies, the emission of SO2 gas is still a problem in terms of environmental considerations.Several studies had been carried out in the past to overcome the drawbacks of the current process. The extraction of Cu from sulfide ores using a chlorination process is one alternative that had been investigated by several researchers. Most chlorination processes used chlorine gas (Cl2) as a chlorinating agent at temperatures between 573 and 1,023 K under an inert atmosphere (Donaldson and Kershner, 1962; Olsen et al., 1973; Kumar, Li and Warren, 1985, 1987; Kanari et al., 1999; Kanari, Gaballah and Allain, 2001)."

Jan 1, 2017

By F. Dehghani, B. Rezaie, T. Ghosh, A. Sachan

Comminution is an integral part of the mineral extraction process. However, the influence of the comminution method (ball and rod mills) on silica and magnetite particle shapes has not been substantially investigated. Shape parameters for fractions of -250+212, -150+125, and -106+75 μm sizes were examined utilizing a scanning electron microscope and a Clemex vision PE image analysis system. The silica particles displayed higher elongation and flatness parameter values for rod mill products, but roundness and relative width parameter values of rod mill products are less than that of the ball mill products. Magnetite particle elongation and flatness parameter values of ball mill products in fraction sizes of -250+212 and -106+75 μm are larger than rod mill products, but roundness and relative width parameter values of ball mill products are smaller than rod-mill products, but for the -150+125 μm size range the result is converse. Furthermore, particle elongation and flatness increased with decreasing particle sizes of silica, whereas, roundness and relative width decreased for both Ball and Rod Mills. In case of magnetite, ball mill products displayed an increase of flatness and particle elongations with decreasing particle sizes but flatness increased and roundness and relative width decreased. Similarly for rod mills, magnetite fractions of -150+125 μm were found to have the largest values of elongation and flatness. INTRODUCTION Comminution alters the size and shape, causes lattice distortion, changes chemical composition, surface area, surface-free energy, and polymorphic transformation of all materials. The quantity and quality of such changes depend on specifications of the material feedstock, the type of mill being utilized, the specific energy input, ambient temperature, and environmental pressure [1]. The shape difference between the milled products depends on different grinding mechanisms and the respective breakage principles that these mechanisms depend on [2, 3]. With decreasing particle sizes, the nature of the particle surface become crucial [1]. The influence of the breakage technique has been found to be non-trivial and heavily dependent on the type of grinding mill used for particle size reduction [4]. Shape is an important industrial parameter for predicting particle behavior in downstream processes. The shape parameter affects the way particles burn, compact, are recovered, flow in fluids, sinter, float, agglomerate, fluidize, interact with pulmonary tissue, cut, abrade, react with chemicals, form structural materials, and retain and permit fluids to flow [5, 6]. The distribution of particle sizes and shapes are important for mining, civil and chemical, pharmaceutical, and various other industries with interest in the population modeling of atmospheric dusts, smoke, and grit [1, 3, 6]. The shape parameter not only affects the chemical, physical, surface properties of particles but is also important for downstream processes [5, 6]. Image analysis has been found to provide detailed information about size and shape of the particles and can be used for the control of product quality [4].

Jan 1, 2019

By C. L. Schneider

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance and is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require the estimation of a large number of parameters unless a structural model of the ore texture can be used. A very simplified textural model based on the use of the modified Andrews-Mika diagram and the PARGEN simulation of multi-phase particles has been formulated and is used to simulate the behavior of a continuously operating laboratory ball mill. A sensitivity analysis for this mill has been done to show the likely effect of model approximations on the predicted liberation spectrum which will be measured.

Jan 1, 1992

By B. Hagemeyer

The trend to higher solids paper coating and to neutral/alkaline papermaking is causing an above average growth in the use of calcium carbonate as both a paper coating and a paper filling pigment. These developments are expected to continue well into the 1990s. Thus, calcium carbonate will account for a somewhat larger percentage of total paper pigment volume. Nevertheless, overall growth in paper tonnage coupled with an increase in filler pigment percentages will create a demand for larger quantities of other pigments as well. Kaolin will continue to be the dominant paper pigment by far, with continued growth though at a somewhat slower rate than calcium carbonate.

Jan 1, 1986

By James C. Cobb

Middle Pennsylvanian (Desmoinesian) coals of certain areas of the Illinois and Forest City Basins contain epigenetic sphalerite and associated minerals in veins, clastic dikes, cleat, and other small-scale structural features. The presence of sphalerite in these coals records information about the geology of coals and coal basins, and represents a potential source for zinc as a byproduct of coal production. Origin of Sphalerite in Coal The origin of sphalerite in coal suggested by Cobb (1) involves sphalerite precipitation from zinc-bearing ?Na-Ca-Cl brines upon contact with sources of sulfur in the coal bed, e.g., pyrite, H2S, and organic sulfur. These brines were essentially at the temperature of the host coals as determined by fluid-inclusion thermometry and vitrinite-reflectance studies. The migration of these brines into coal beds may have been caused by compaction of sediments due to continued sediment loading of the coal basins. Zones of high permeability such as sandstones and the coals themselves presumably acted as conduits for the movement of the brines. The open spaces where sphalerite was deposited resulted from minor deformation associated with differential compaction and cleat formation enhanced by volume shrinkage during coalification.

Jan 1, 1982

The evaluation of Abandoned Mined Lands can involve the investigation of very large areas of land. Often, the locations of critical areas or impending problems are unknown, and are not easily identified from the surface. Microseismic monitoring has been demonstrated to be effective in identifying potential instabilities and active movement in mines from distances of several kilometers. By placing sensors in proximity to, or in contact with, a high acoustic conductance layer close to the mined zone, large areas can be monitored for potential problems with a minimum of sensors and drillholes. As part of a U.S. Bureau of Mines contract, a prototype system was developed to identify and locate potential instability problems over wide areas of land. Once a problem area has been located, the system can be used to analyze the type of the problem, its size, relative degree of instability, and potential for damage. Continued monitoring after application of remedial measures can effectively determine the efficacy of those measures.

Jan 1, 1993

By Bob Munz, Ry Stone

To facilitate the installation of the longwall equipment for each extraction panel, West Elk mine develops set-up room roadways that are between 26.5 and 30.5 feet wide. Historically at the mine, the set-up room roadways have been driven in a single 20-foot-wide pass, then incrementally widened to the required width during installation of the longwall shields. The first pass roof is supported with a generic roof support plan consisting of partially encapsulated roof bolts and point-anchored cables. This ground support plan was utilized regardless of the geotechnical conditions encountered in the roadways or consideration of the required stand-up time of the roadway before the longwall shields were installed. This "blanket" approach tends to result in over-conservative or inappropriate roof support designs, particularly in changing geotechnical environments. Guided by the desire to optimize the ground support plans and increase mining efficiency for future set-up rooms, the West Elk mine and Agapito Associates, Inc. have developed and implemented a strata management program. Strata management, as a formal and structured process, allows ground support and mining methods to be tailored to the anticipated and encountered geotechnical environment in a con- trolled manner (Thomas 2007). To arrive at adequate site-specific ground support plans for the set-up rooms at the mine, several struc- tured processes were utilized. Firstly, the geotechnical environment was characterized by examining the roof lithology and geomechanical properties from nearby rock core obtained from exploration boreholes. To increase both mining efficiency and continuity, and to achieve longer stand-up times before the longwall shields are installed, a multi-pass approach was implemented into the design. During mining, the geotechnical conditions of the roadway are mapped, and the roof is strategically surveyed with a borescope. This process was used to ensure that the encountered ground behavior was in alignment with the design standards used for the roof support design. To support this process with measured data, roof extensometers were strategically installed throughout the roadway. This data was used to monitor the magnitude of roof displacement at various horizons and record displacement rates up until the longwall shields were installed. Lastly, a Trigger Action Response Plan (TARP) was used during mining to cater for any unforeseen changes in ground conditions that would warrant additional con- trols such as increased monitoring or the installation of additional ground support. This paper presents two case histories at the mine where the above strata management approach was implemented to arrive at a site-specific ground support plan. The main changes to the mine's ground control plan included a multi-pass mining approach, the utilization of fully encapsulated roof bolts, and the transition to a stiffer roof support system. The geotechnical mapping, the roof borescope results, and the roof extensometer data will be presented to demonstrate the effectiveness of the ground support system up until the longwall shields were installed in both presented cases.

Jun 25, 2024

By B. Li

"Sepiolite is a magnesium-rich, porous, and fibrous clay mineral with broad applications. These applications take advantage of sepiolite’s high specific surface area and unique nano-sized channel structure. Over the past years, numerous materials and techniques based on the structure and property of sepiolite have been developed. This article reviewed the recent achievements in developments and applications of sepiolite in environmental protection, catalysis area, and nanocomposites. The prospectives of sepiolite applications is also discussed. INTRODUCTION Sepiolite is a magnesium-rich, porous, and fibrous clay mineral. The typical chemical formula of sepiolite is Si12Mg8O30[OH]4[OH2]4·8H2O [1]. Sepiolite has a high specific surface area and nano-sized channels because of its special structure [2]. This unusual crystal structure projected onto the [001] plane is shown in Fig.1 [3]. As it can be seen, silicon and oxygen atoms make up for the tetrahedral structure and magnesium and oxygen atoms form octahedral structure, respectively. Those tetrahedral-octahedral-tetrahedral ribbons expand boundlessly in one direction, leading to the special fibrous structure of the sepiolite. Every tetrahedral-octahedral-tetrahedral ribbon is combined to the next by an inverted Si–O–Si bond, which causes an interlaced layer with a continuous tetrahedral sheet and a discontinuous octahedral sheet. Terminal MgO at the edges of the ribbons is coordinated with two structural water molecules, which can form hydrogen bonds with zeolitic water molecules that are located in the channels running parallel to the fiber axis [3,4]. The Mg2+ ions inside the channels can be exchanged with other cations in solution. Therefore, sepiolite can be used to remove metal cations from aqueous solutions [5,6].It can be seen from Figure. 1 and Table 1 [7], the unique structure endows sepiolite with a substantial surface area and nanoscale channels. Its specific surface area reaches 320 m2/g and channel dimensions up to 3.7×10.6 Å. There are three active adsorption sites on the surface of sepiolite: one is oxygen atoms of the Si-O tetrahedron. The second is the structural water molecules paired with magnesium ions at the edges of the ribbons, which can form hydrogen bond with adsorbent. The last one is the Si-OH groups due to the breaks of the Si-O-Si bonds on the surface of Si-O tetrahedron. Thus, sepiolite has strong adsorption ability which has been widely used in environmental protection. Moreover, sepiolite has many significant features such as good mechanical and thermal stability, rheological property, porous, and easily modification, making it be a hotspot in chemical and biological researches. However, with the development of technology, broader and more advanced applications of sepiolite have been carried out in recent years. In this study, the recent achievement in sepiolite applications is summarized, the further tendency is also discussed."

Jan 1, 2018

By J. A. Murray

Maintaining satisfactory air quality in electrowinning tankhouses is problematic and costly, particularly as plant operating current densities have increased. Conventional approaches have not proved completely effective. These include the use of beads, hollow spheres, surfactants and coalescer devices. They require powerful ventilation systems to be installed. As workplace and environmental regulations become more stringent, containment of the acid mist at its source is more attractive. An electrode cap system based on this approach has been developed and tested in two commercial copper electrowinning tankhouses.

Jan 1, 1996

By Graham A. Brown

Activities in offshore mineral exploration In Australia are increasing almost daily, at such a rate that this report will rapidly become out of date. At the time of writing, February 1967, there were no commercial discoveries of offshore minerals reported in Australia, although there has been definite encouragement in many fields. While this initial encouragement has not revealed any commercial mineral deposits offshore hopes are running high in Australia for success in 1967. Why should mineral deposits be expected offshore in Australia in the first place? The reasons are many. The minerals to be discovered also are many. The reasons are based on the history of alluvial and beach mining activities in Australia&apos;s past and at the present time, and on the physical environment of the vast Continental Shelf which surrounds the continent. A brief examination of the two primary features which are necessary before offshore mineral exploration can be contemplated should be, undertaken. Two favourable environments are necessary; firstly a Continental- Shelf to form a physical environment for the accumulation of the mineral deposits, and secondly a favourable political-legal environment to give the exploration companies adequate protection during exploration, and suitable long term arrangements for the exploitation of the deposits after discoveries have been made. Australia is well endowed with both of these.

Jan 1, 1967

By R. L. Ziegfeld

It has often seemed to me that people are too prone to turn to new and untried materials in an effort to solve their problems, without giving sufficient consideration to the old stand-bys, except as a last resort, It?s a little like middle-aged men who are swept off their feet by the fresh beauty of a young girl without first considering the many advantages that a more mature woman has to offer. Maybe it?s because, like the older woman, the older materials have to make a determined effort to keep themselves looking young and attractive. T at?s just about the situation with which the lead industry is laced. We have to make a determined effort to keep lead looking young and attractive to industry. However, there is one difference and it is important, Lead can not only be kept looking young, but it can, in fact, actually be kept young, This results from two things. First, industry and technology are constantly changing. For example, we have known for years that the density of lead makes it ideal to stop gamma rays, but it is only recently that atomic fission as a source of gamma radiation has become an important tool of industry, That makes old knowledge about lead useful in developing a new market for it.

Jan 1, 1958

By J. Sohn

The most promising near-term alternative to fuel cell driven vehicles is probably Hybrid Electric Vehicle (HEV or EV) technology. HEV technology combines the best characteristics of fuel-driven engines, electric motor drives, and energy storage components. It is designed with a combustion engine that functions as the primary power source, and an electric power storage system that functions as the secondary power source. The presence of the secondary power source allows designers to size the combustion engine for cruising power requirements. A new energy source for HEV or EV market will become lithium ion batteries (LIBs) in the near future. LIBs for HEV or EV has large scale about more 10,000 times than small size one for IT devices in order to achieve high electric density/capacity and high efficiency, etc. In those reasons, physical treatment of the batteries is more difficult for stable dismantling in comparison with the smaller one. Hybrid vehicle sales will grow by nearly 400 percent during the next seven years, according to a new report from analyst firm ABI Research. By 2013 hybrids will make up 6 percent of annual U.S. auto sales. The traction battery pack will become air-cooled LIBs which consists of several modules of Li ion battery and connected in series/parallel configuration to provide about >450 VDC, >150 kW peak power, and >80 Ah capacity. As the use of these batteries tends to increase significantly for the next years, it is relevant issues that development of new recycling methods as well as optimization of existing processes to treat spent LIBs for HEV have being addressed in order to obtain sustainability. In this study, physical treatment containing stable electrical discharge of spent LIBs for HEV was carried out for recovery of valuable metals from the batteries. Also In order to increase the yield of valuable metals through physical treatments such as electric discharge of spent batteries, crushing, and classification, we also focused on the recovery of cobalt from +8 mesh fraction due to its large portion in crushed intermediates.

Jan 1, 2010

By G. J. Trezek

The use of polysilicates for treating heavy metals in soils and mining sludges is discussed. Results of the treatment are given for soil contaminated in a metal scrap yard operation and for copper mining processing sludges. The types of metals of concern are arsenic, lead, copper, nickel, cadmium, and zinc. The application of the treatment is predicated on the mixture and relative concentrations of the metals as well as the material matrix. Reductions in soluble concentrations (STLC or TCLP) of one to two orders of magnitude can be achieved with relatively small additions of silicates and cementitious materials.

Jan 1, 1992

By Donald L. Freed

Design, development, factory test, and in-mine evaluation plans are presented for an Automated Extraction System (AES) that has been designed to fill needs which are present in the Mining Industry. The philosophy of design and proposed operation of the machine, as well as the relationships between these factors, and final machine configuration are reviewed. The AES is designed to overcome production problems resulting from the regulation of roof control, clean-up, ventilation, dust suppression, and operator protection required by the Federal Coal Mine Health and Safety Act of 1969. The design permits more continuous operation and greatly improves operator safety. The machine is a full-face drum-type continuous miner which includes self-advancing, continuous temporary roof support. Onboard self-advancing face ventilation, dust suppression, and air scrubbing equipment are also included in the design. A further improvement over existing equipment is the incorporation of an automatic programmed cutting cycle control system. All mining functions including movements of the roof support system are handled by this automatic system.

Jan 1, 1977