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By Brendan Donnelly, Lasitha Piyathilaka, Jung‑Hoon Sul, Sanghyun Jeong, Benjamin Probyn

Premature failure of armoured face conveyor (AFC) chains due to corrosion is a significant proportion of the unplanned downtime experienced on longwall equipment. The AFC chains are constantly in contact with water and wet coal. The premature failure issue of AFC chains has become more prominent since the introduction of longwall top-coal caving with its additional AFC. Reverse osmosis (RO) is a popular water treatment method for reducing salinity and dissolved solids, but its impact on the corrosion of the AFC chains is unclear. This study has been commissioned to investigate the direct effects of RO water on the corrosion of AFC chains. An immersion test was carried out using AFC chain steel submerged in two water samples: untreated dam water and treated water from an RO treatment plant. Elemental analysis was conducted for both water samples, and four corrosion indices were measured for both water samples. The RO water more vigorously dissolves calcium carbonate scales leading to increased corrosion of the AFC chains although the dam water has much higher levels of calcium, chloride, sulphate, sodium, and magnesium. Bicarbonate ions are the main alkaline factor of water that provides the buffering capacity to acids. Decreased alkalinity without balancing other ions in water causes high corrosivity and decreased scaling tendencies.

Oct 16, 2023

By H. B. Miller

Contract Incentives have long been employed in the underground hardrock industry as a tool to influence employee performance, enhance productivity, and control labor costs. While traditionally structured to establish a direct correlation between performance and compensation, many contract programs have evolved into elaborate systems that promote strategies often viewed as independent of productivity. This paper presents the findings of research into these contract incentives and was conducted with the cooperation of 33 mines utilizing a spectrum of employee compensation and incentive programs. Emphasis of this analysis focuses on the types of production contracts observed and their role with respect to employee earnings.

Jan 1, 1994

By E. J. Owen, S. Cherotich, V. T. McLemore

Breccia pipes are vertical pipe-like columns of rocks that provide conduits for fluid flow and open spaces for mineral precipitation, hence are focus areas for exploration. In the Gallinas Mountains, Lincoln County, New Mexico, there is recorded production of Cu, Pb, Ag, F, Fe, REE (as bastnäsite), and Au from 1902 to 1980, but no production reported from the breccia pipes. Previous studies described the occurrence of REE in breccia pipes, but their transportation and deposition controls are still unclear. The aim of this research is to characterize the magmatic-hydrothermal breccia pipes in order to understand the geochemical and physical conditions of deposition of REE and gold in the breccia pipes found in the Gallinas Mountains. There are more than 20 exposed breccia pipes that form a NE-trending belt about 3–5 kilometers, mostly gray-brown and consist of angular- to sub-rounded rock fragments, some host high concentrations of REE (80,500 ppm total REE) and Au (175 ppb). Preliminary studies suggest they are magmatic and intruded into the host rock and, subsequently, hydrothermal fluids precipitated F-REE and Au along the edges of some breccia pipes. More studies are underway to test this hypothesis.

Feb 1, 2023

By Steven W. Hunt, Glen R. Frank

Assessment of abrasivity and cutter life are necessary to properly manage risks when tunneling in mixed face ground which includes ground with cobbles and boulders. Maximizing cutter life requires: (1) abrasivity and strength parameters for soil matrix and rock clasts, (2) methods of combining both, (3) proper selection of cutters and (4) modified TBM operation including use of boulder detection methods from the TBM to help make operation decisions. This paper presents approaches for addressing these factors sufficiently to improve tunneling success in mixed-face and cobbly-bouldery ground. Current laboratory abrasivity testing will be assessed along with equivalent quartz content correlations to soil matrix and rock clast abrasivity. New approaches to combining abrasivity testing of both the soil matrix and rock clasts for various cobble and boulder volume ratios will be suggested to estimate cutter life and intervention intervals. Methods for detecting boulders and using detection data to modify TBM operations to minimize boulder impacts are provided.

Jun 13, 2021

By D. Men, R. Q. Honaker, J. C. Hower

"Maceral separation is one possible technique to expand coking coal resources, either by increasing the blending ratio of non- or slightly caking coal or rationally utilizing the coking coal according to the different behaviors of macerals in coking. The success of maceral enrichment for a given coal using flotation is dependent on the differences in flotation kinetic rate among macerals. This paper presents the flotation rates and zeta potentials of the vitrinite-rich and inertiniterich maceral concentrates obtained from six coal samples of different ranks – from high-volatile B bituminous coal with mean random vitrinite reflectance (Rrandom) of 0.64 percent to low-volatile bituminous coal with Rrandom of 1.73 percent – using a float-sink procedure. The flotation results show that vitrinite-rich concentrates can be produced in tap water using froth flotation only with frother for the high-volatile B and A bituminous coal samples, but there was no good performance for the high-volatile C bituminous and medium- to low-volatile bituminous coal samples. The zeta potential results show that froth flotation could probably separate the high-volatile C bituminous coal samples well by adjusting pH, but there was no good performance for the higher-rank coal samples. IntroductionMetallurgical coke is used in blast furnaces for steel production and is produced by the carbonization of coking coal. Because caking coals are rare and expensive, they are often blended with non- or slightly caking coals. Considering the tight supply-demand situation for coking coal in China, it is important and urgent to develop highly efficient technologies for rationally utilizing and expanding coking coal resources (Mochizuki et al., 2013)."

Jan 1, 2015

By HONGWEI YANG, Lili Zhang

The oxidation behavior of copper smelting slag under non-isothermal conditions was studied by thermal analysis. The results indicate that the copper slag is mainly composed of fayalite ( Fe2SiO4) and magnetite ( Fe3O4). The oxidation behavior can be divided into two reaction stages with the increase in temperature; the first stage is the oxidation of fayalite to magnetite, and the second stage is the oxidation of magnetite to hematite. The two reaction stages cannot be strictly separated; that is, the reaction of fayalite is not complete, and magnetite has begun to transform into hematite. Based on the TG (thermogravimetric) curves, the ABS (Achar–Brindley–Sharp–Wendworth) differential and the Coats–Redfern integral methods were employed to investigate the oxidation kinetics of copper slag during the continuous heating process. The oxidation of fayalite into magnetite and amorphous silica phases occurs mainly in the temperature range of 673 to 1083 K. The activation energies calculated by the two methods are 193.69 and 195.52 kJ mol− 1, respectively. The reaction is consistent with Avrami–Erofeev equation, and the mechanism of oxidation is random nucleation and growth. The oxidation of magnetite to hematite occurs at 1083–1303 K. The activation energies are 308.79 and 328.77 kJ mol− 1, respectively. The mechanism conforms to the Jander equation and is controlled by the two-dimensional diffusion.

May 16, 2022

By V. Miller

C. Hertzler The difference of means of milling characteristics by rock and ore type is tested in a statistical manner in the paper. The null hypothesis being tested is that the sample means of two different populations are equal. It is assumed that the null hypothesis is true when performing the test. Because of this, acceptance of this hypothesis leads to the conclusion that the sample means of the two different populations are equal (or there is no significant difference between the sample means), not that the samples come from the same population, as the author asserts. Rejection of the null hypothesis leads to the conclusion that the sample means of the two different populations are not equal. A P value for this test is reported in Table 2 and is incorrectly identified as the probability that the two samples came from different populations. Actually, what was recorded was 100(1 - p) where p is the usual p-value. The usual p-value measures, on a scale of zero to one, the extent to which the data agree with the null hypothesis. It is the probability of observing a value of the test statistic (Z score) that is at least as contradictory to the null hypothesis as the one computed from the sample data (McClave and Dietrich II, 1982). The author makes no mention of the fact that were these tests to be conducted together, the chances of determining that the null hypothesis is not true when it is really true are increased considerably (Snedecor and Cochran, 1980). This is a multiple comparisons problem and should be dealt with accordingly. The usual methods involve adjusting the level of the individual tests. Table 2 reports an incorrect 100(1 - p) value in the comparison of concentrate grades for other rock types with .30 to .69 % Cu vs other rock types with .70 + % Cu; 86 % should be 98.6 %. Although the article can be criticized for poor data presentation and discussion of that data, the point the author makes regarding the use of these statistics in the ore reserve estimation process is well taken. It does not appear that inaccuracies in the statistical interpretations have hindered that usefulness. References McClave, J.T., and Dietrich, II, F.H., 1982, "Statistics," Dellen Publishing Co., San Francisco and Santa Clara, CA, 766 p. Snedecor, G.W., and Cochran, W.G., 1980, "Statistical Methods," The Iowa State University Press, Ames, IA, 561 p. Reply by V. Miller After reading Ms. Hertzler's comments, it appears that the differences noted were basically semantics. If the paper is ever presented at a math symposium, some changes will be needed. When deciding the best way to present the data to mining engineers and geologists, I decided that presenting the probability that the two sample groupings came from different populations (reverse to the Null hypothesis) was easier and would require less verbage to explain. Hence, the 100(1 - p) difference which was noted. Ideally, I would have preferred to give the recovery and concentrate grades, then comment which ones had significant differences. Unfortunately, Kennecott Corp. did not grant permission to publish the ore body's actual recoveries and concentrate grades. The conclusion is that there was, as expected, a relationship between the ore's geologic properties and the metallurgical properties, and by determining this relationship, the overall mineral model was greatly improved.

Jan 8, 1984

By Z. Zhang, M. S. Gonzalez, M. de P. Bueno, P. Holopainen, S. Luukkanen

"Despite being a field of study that requires practical knowledge and experience, mining engineering education follows the same pattern in most mining universities around the world, consisting of theoretical courses and laboratory-based practical modules (Mischo, 2015). The possibility of having practical training in real mining conditions on actual mine sites or processing plants is limited, while the only contact that undergraduate students have with mining operations during their time of study is usually through shorttime internships or visits in the context of educational trips. Real integration between universities and the mining industry may be scarce, which does not help students to observe the actual processes and thus understand the whole picture of mining operations.Indirect practical training is now possible since that technology is shifting from mechanical to digital, and the use of virtual reality — in the context of Mining 4.0 — can provide additional experience to the learning process. However, virtual reality is limited to the visual impression and is also limited in actions (Binder et al., 2018). In any case, when there is not a proper pragmatic view of how the different disciplines link to each other, especially if there is a lack of communication, unfortunately the results could be seen at a later stage in the mines as a poor performance of professionals and workers.Another major challenge for educating specialists in the mining sector is that experimental mines suitable for practical education, where the skills and knowhow could be developed and/or enhanced, are rare worldwide. Such research and educational (R&E) facilities are practically former metal ore mines that have been transformed into experimental sites. Besides being limited in number, not all facilities of this kind serve both a research and educational purpose.An early example of asolely experimental mines is the Luossavaara-Kiirunavaara Mine site operated by LKAB in Sweden, where systematic research on rock mechanics and mining engineering was successfully carried out in the 1980s. As a result, the developed underground mining technology was applied in LKAB’s mines at a later stage. There have also been research mines within collieries such as the former Lake Macquarie Mine at New South Wales in Australia and the Zeche Tremonia Mine in Germany), but these are no longer in operation (Mischo, 2015)."

Oct 1, 2019

By J. R. Sims

Gold assays from production blastholes in the Mercur Hill Pit were used to delineate known ore zones and to determine how well previous exploration drilling defined these zones. The most important factors causing inadequate ore zone definition were: 1) inappropriate location of drill holes relative to the ore zones, 2) presence of stopes from previous mining, 3) sampling and assaying errors, and 4) smoothing of the ore zone boundaries during ore reserve estimation. Infill drilling strategies were evaluated to determine the efficiency with which a given drill pattern defined the known ore zones. A drilling strategy was developed which improved ore zone delineation when compared to techniques which maintained uniform drill spacing.

Jan 1, 1992

By William Gleason

"It is the largest mining exhibition in the world that attracts thousands of attendees from around the world to Las Vegas, NV once every four years. Despite the recent struggles in the mining industry, MINExpo International 2016 promises to be as big as ever. In the following pages, Mining Engineering takes a look what some of the more than 1,800 companies plan to showcase during the three-day exhibition.CaterpillarCaterpillar will support MINExpo 2016 with an exhibit showcasing machines, technology, expertise and practical knowledge that miners can apply to help address their cost, productivity and efficiency challenges in today’s mining environment.Caterpillar will once again occupy the largest space at the event and will showcase both surface and underground machines, but the talk at the booth will focus on how Cat technology and know-how combines to help mining operations address and solve the issues that are most important to them. The main stage in the exhibit will feature presentations describing how mining companies, Cat dealers and Caterpillar work together to improve operations.“The challenge for all in the mining industry now is to optimize operations — to drive costs down while creating sustainable businesses that can weather downturns,” said Caterpillar Resource Industries group president Denise Johnson. “We believe that through our expertise and the knowledge of our dealers —combined with innovative technologies and our growing data analysis capabilities — we can help them not only survive, but thrive in these challenging times.” Johnson was selected by the National Mining Association (NMA) to chair MINExpo 2016. “Chairing this show is a great honor, and it’s a testament to Caterpillar’s partnership with this critical industry,” she said. “We’re proud to be a long-time supporter of the NMA, and we are excited to participate in another MINExpo. It’s an opportunity for us all to learn from each other how to increase productivity, control costs and improve overall operations.”Surface mining displays. The surface mining section of the Caterpillar exhibit will showcase the new MD6420C rotary drill. This is autonomy ready and optionally equipped to leverage the safety and productivity benefits of Cat MineStar Terrain. This high-precision drill management system optimizes utilization and improves drilling and blasting operations by accurately guiding the operator and improving precision of hole placement and drilling depth — and the next step is fully autonomous operation, Command for drilling. The third-generation drill incorporates proven Cat components throughout for superior reliability and durability."

Sep 1, 2016

By RICKARD HANSEN

With vehicles frequently found in underground mines and tyres being a major fuel item, the risk of tyre fires will be severe underground. This study presents an in-depth analysis of tyre fires on mining vehicles to increase the knowledge of the risk, applying data from full-scale fire experiments and CFD simulations. It was found that the wheelhouse of the loader caused an increase in the flame tilt angle of approximately 10%, decreasing the flame impingement and heat flux downstream. The flame temperature of the drilling rig tyre was found to be approximately 7% higher than the loader tyre, increasing the risk of igniting adjacent fuel items. The construction of the wheelhouse/mudguard will contribute to a longer flame length by creating a fuel-rich environment. The CFD simulations predicted higher flame tilt angles for the drilling rig case for higher flow velocities, indicating the influence of a varying wheelhouse/mudguard construction and tyre geometry on the flame tilt angle. The construction of the loader resulted in a flow behaviour, where the short distance to the front mudguard/tyre and the separation of flow directly downstream of the protruding construction led to fire gases being steered past the front mudguard/tyre. In the drilling rig case, the longer distance to the front mudguard/tyre led to fire gases being directed towards the body of the vehicle after passing the area with flow separation. An increased knowledge of the tyre fire risk on mining vehicles and mitigating measures would improve the fire safety in underground mines.

Feb 10, 2022

By Xuezhong Wang, Hao Guo, Tao Tu, Qingsheng Liu

The scheelite concentrate was leached with a mixture of sulfuric and oxalic acids. Chemical compositions, mineral phases, and morphology were characterized by XRF, XRD, and SEM–EDS. Based on the results of the single-factor experiments, the response surface methodology (RSM) was chosen to optimize the leaching parameters: temperature, time, and concentrations of sulfuric and oxalic acids. The RSM results indicate that the optimum values for those parameters are as follows: temperature 72 ℃, sulfuric acid concentration 1.48 mol/L, oxalic acid concentration 0.96 mol/L, and reaction time 2 h. Under the optimal leaching conditions, the model predicts a maximum leaching yield of 99.5%, compared to the value of 99.1% obtained experimentally, that is, a discrepancy of only 0.04%. This good correlation shows that the quadratic polynomial equation obtained by the RSM optimization is reliable. The importance on leaching parameters of scheelite is, in decreasing order, temperature, time, sulfuric acid concentration, and oxalic acid concentration.

Oct 11, 2021

By Andrea Brickey, JUDITH BUABA, RICHARD AMOAKO

The global mining industry has recorded significant declines in accident and injury rates attributed to the advancement in technology, increased enforcement, and safety consciousness. A goal of the mining industry is to achieve zero injury and occupational illness on all mine sites, prompting increased research into ways to further reduce mine accidents. A machine learning technique known as multiclass logistic regression is applied on a 10-year injury dataset from the Mine Safety and Health Administration (MSHA) to determine a miner’s susceptibility to a class of injury and to help identify significant risk factors associated with different classes of injury. The data is aggregated based on injury classification to provide statistically relevant results. The analysis identifies specific risk factors that influence a mine worker’s susceptibility to a given class of injury, i.e., non-fatal with no days lost or restricted activity, non-fatal with days lost and/or days of restricted work activity, and fatal and total permanent or partial permanent disability. These factors include miner’s age, mine type (coal vs. non-coal), experience on the current job (years), shift start time, employment type (operator vs. contractor), mining district, and type of accident. The results of the analysis indicate that a miner’s experience on the job, i.e., the number of years worked in a current job, is a significant risk to injury occurrence, even for those with decades of total mining experience. We further show the differences and similarities between the surface and underground mine incidents.

Nov 3, 2020

Explosives are used to mine coal. Any blast results in three size categories of products, namely over-, middle-, and under-size. Boulders can still be broken smaller in further operations after blasting. The under-size, for instance coal fines, negatively affects the mining efficiency. Their reduction ensures better returns. The paper concerns investigations aimed at reducing coal fines' generation. Inherent fractures are identified as one of source of fines. The discussion is therefore centered on establishing a relationship between the fracture occurrence, the explosive properties and the blast outputs evaluated in terms of the fines generated.

Jan 1, 1996

By Yuemin Zhao, Wenxuan Liu, Maoming Fan, Zhanyuan Long

"Coal is mainly composed of energy-producing elements carbon and hydrogen. In addition to these elements, coal usually contains many other valuable elements, including iron, aluminum, silicon, rare earth elements, lithium, gallium, germanium, vanadium, uranium, titanium, scandium and phosphorus. These coalassociated elements are significantly enriched in coal combustion byproduct fly ash because the majority of the main components, carbon and hydrogen elements, being removed. Table 1 provides the chemical composition range of the main element oxides in 12 Chinese fly ash samples collected from coal power plants located in Northeast China, Northwest China, Southwest China and Southeast China. It can be seen from Table 1 that the major mineral components of different ashes are similar, but the bulk chemistry of different fly ashes may vary due to the changes of ratios of the mineral components in different coals. The major mineral components in various Chinese coal combustion fly ash are silicates, iron oxides and unburned carbon.Chinese coal fly ash usually contains about 5 to 15 percent of unburned carbon, which are generally chars with irregular shapes and wide particle size distribution. In addition to unburned carbon, XRD analysis of four Chinese fly ash samples from Liaoning, Shanxi, Guizhou and Shandong provinces indicates that the fly ash samples are composed of minerals such as quartz (SiO2), mullite (3Al2O3.2SiO2 or 2Al2O3.SiO2), hematite (Fe2O3), maghemite (gamma form of hematite, ?-Fe2O3) and magnetite (Fe3O4). The mullite and quartz particles are usually present as spherical particles because they are formed by melting clays, feldspars, quartz, calcite and other common minerals in coal during coal combustion. The silicate particles have usually entrapped gas to yield hollow spherical particles because their lower melting point facilitates gas entrapment.The iron oxides are usually spherical also. The magnetite (Fe3O4) is derived from pyrite (FeS2), hematite (Fe2O3), siderite (FeCO3) and limonite (2Fe2O3.3H2O) in the coal. Maghemite (?-Fe2O3) is formed by dehydration of the mineral hydrohematite (?-FeO(OH)) and/or oxidation of magnetite (Fe3O4) during coal combustion. Maghemite (?-Fe2O3) and magnetite (Fe3O4) are strongly magnetic, so they are recovered from Chinese coal fly ash and widely used for coal processing in China (Fan et al., 2005, 2000)."

Jan 3, 2018

By William Watson

Coal production in the United States in 2010 increased to a level of 960 Mt (1,085.3 million st), according to preliminary data from the U.S. Energy Information Administration (EIA), an increase of 1 percent, or 9.43 Mt (10.4 million st) above the 2009 level of 975 Mt (1,074.9 million st) (Table 1). In 2010, U.S. coal consumption increased in all sectors except commercial and institutional, while total coal stocks fell slightly for the year. Coal consumption in the electric power sector in 2010 was higher by 4.5 percent, while coking coal consumption increased by 37.9 percent and the other industrial sector increased by 7.1 percent. The commercial and institutional sector, which prior to 2008 had been called the ?residential and commercial? sector and is the smallest of all the coal-consuming sectors, declined by 3.1 percent in 2010. (Note: All percentage change calculations are done at the short tons level.) U.S. coal exports increased from the 2009 levels due mostly to higher demand for metallurgical coal, while coal imports decreased for a third year in a row. The increase in coal consumption for electric generation during the year was the consequence of improving domestic economic conditions further bolstered by a cold winter and warm summer in important coal-consuming regions. Preliminary data show that total generation in the electric power sector (electric utilities and independent power producers, including useful thermal output) in the U.S. increased in 2010 by 4.2 percent. Coal-based generation also increased, resulting in a 38-Mt (42-million st) increase in coal consumed in the electric power sector. Coal use in all the sectors other than the electric power sector increased by 13.9 percent to a level of 65.9 Mt (72.7 million st).

Jan 1, 2011

By E. Lee Bray

"Editor’s note: The editors thank those who make this annual issue possible. A special thank you goes out to the Industrial Minerals Annual Review editor, to the Industrial Minerals & Aggregates Division Technical Committee chair and vice chairs, and to the authors of the individual commodity profiles.Jim Norman, member SME, of Tetra Tech Geo, is the industrial minerals annual review editor. Edgar Blanco, member SME, of Freeport- McMoRan, is chair of the Industrial Minerals &Aggregates Division’s Technical Committee.The technical committee vice chairs include:• NickTushar Gupta and Sallie Gaillard, of the USGS, members SME, agricultural materials.• Abhishek Choudhuryand Xihui Yin, members SME, of Montana Tech and Kemira, repectively, ceramic and refractory materials.• Bobbi Strange and Riddhika Jain, members SME, of Outotec, Martin Marietta and Outotec, respectively, chemical raw materials.• Snehamoy Chatterjee, Alyssa Kendir and Alind Chandra, members SME, of BMT, Universityof Kentucky and Michigan Tech, respectively,construction aggregates.• Subham Verma, Gauran Soni and Freddy Sime, members SME, fillers and pigments.• Kaiwu Huang, Thomas Hilderbrand and Ricardo Santander members SME, of Virginia Tech, Thiele Kaolin and Carbo Ceramics, respectively, sorbents, filters and process aids.• Rhaghay Dubey and William Rapier, members SME, of Outotec and a consultant, respectively, specialty minerals.On behalf of ME readers, the editors thankTwo U.S. alumina refineries produced an estimated 1.5 Mt (1.65 million st) of alumina from imported bauxite in the United States in 2018. The 500-kt/a (550,000-stpy) refinery in Burnside, LA, owned by Almatis Inc. produced specialty alumina used in the abrasives, ceramics, chemical and refractory industries. The 1.2-Mt/a (1.32 million-stpy) refinery in Gramercy, LA, owned by Noranda Alumina LLC produced alumina mostly for use in aluminum smelters but also produced specialty alumina. An upgrade project at the Gramercy refinery to convert 200 kt/a (220,000 stpy) of capacity to produce more profitable specialty alumina was completed in the first half of 2018, and another project to increase capacity was started but a completion schedule was not available. The amount of new capacity was not disclosed, but it would be used to produce nonmetallurgical grade alumina. The 2.3-Mt/a (2.5 million-stpy) refinery in Point Comfort, TX, which was temporarily shut down in March 2016, remained closed throughout the year."

Jul 1, 2019

By R. Kramer, A. Habibi

A ventilation survey was conducted in an underground longwall trona mine. The mine is relatively shallow and categorized as a gassy mine. The ventilation system includes three intake and six exhaust shafts, and three surface axial fans ventilate the mine in a blowing configuration. Airflow quantity, pressure losses and air psychrometric characteristics were quantified, and the influence of moving cages and skips in the shaft examined. The benefits of utilizing high-accuracy digital pressure transducers and advanced psychrometers were seen when undertaking a “leapfrogging” survey to gather data needed to build a computer ventilation model. Two underground booster fans with VFDs are idle but available at the mine. The ventilation model was used to determine the optimal booster fan locations to decrease operating cost by reducing the load carried by the main fans. A leakage study was conducted to evaluate the effects on the system of additional pressure from a booster fan. The study finally prepares a future ventilation model for the next 15 years of mine operation and investigates the effect of proposed scenarios.

Jan 1, 2014

By Robert D. Thomson

The plastics industry runs into the billions, both in the dollar value of its finished, products and in the pounds of plastic raw material produced. It is, too, one of the fastest growing industries with a 300 percent increase in production in the past ten years. Informed estimates set 5.9 billions pounds as the plastic volume for 1959. Statistically, this is equivalent to a per capita consumption of 25 pounds in the United States. Plastics are man-made materials in contrast to natural materials like wood and are a family of materials -- not a single material - each member having special advantages. A generally accepted definition; for plastics is; a large and varied group of materials which consist, wholly or in part, of combinations of carbon with oxygen, hydrogen, nitrogen, and other organic and inorganic elements. This, while solid in the finished state, at some stage in its manufacture is soft enough to be formed into various shapes, most usually through the application either singly or together of heat and pressure. Many combinations and many different materials are thus possible. Therefore, for purposes of simplification, most plastics can be classified under one of 14 recognized basic family groups. These groups in turn generally can be further classified into one of two major subdivisions - thermosetting or thermoplastics. A few plastics are in between and they can be formulated to be either thermosetting or thermoplastic.

Jan 1, 1960

By Y. Lahaye, O. Martinsson, B. I. Palsson

"Four main and three minor rare-earth-element (REE)-bearing minerals were identified and quantified in the Kiirunavaara apatite iron ore tailings using optical microscopy, an electron probe microanalyzer (EPMA) and a mineral liberation analyzer, and their chemical compositions were analyzed by the EPMA and laser ablation inductively coupled plasmamass spectrometry. REEs are shown to be contained in the minerals apatite, monazite, allanite, titanite, zircon, thorite and synchysite. In zircon, thorite and synchysite, they occurred in only trace amounts and contributed limited amounts to the total REE budget, and these are consequently of minor importance. Monazite occurred as inclusions in apatite and as free particles, 90 percent liberated. Allanite occurred to some degree in mixed grains with magnetite but also as free particles. Monazite mainly reported to the apatite concentrate, while allanite and titanite largely went to the tailings, the latter preferably to those fractions smaller than 38 µm. The amount of titanite in the finest tailings fraction was 2.3 weight percent, containing close to 1 percent REEs, with heavy rare earth elements (HREEs) making up 28 percent of the total REEs. However, a texturally distinct group of titanite grains showed an HREE/REE ratio of up to 67 percent. Furthermore, titanum dioxide analyses indicate that titanite is preferentially released into the tailings from the secondary magnetic separation step in the concentrator. Our data therefore suggest that titanite, occasionally enriched in HREEs, can be extracted from the processing stream and might thus be considered a new source for REEs at Kiirunavaara and similar deposits.IntroductionDeposits of apatite iron ores are the major source for iron in the European Union and are exploited by Luossavaara-Kiirunavaara AB (LKAB) in several mines in the Kiruna-Malmberget area in northern Sweden. Kiirunavaara is the largest of the apatite iron orebodies in Sweden, comprising more than 2 Gt of iron ore with 60 to 68 percent iron (Fe). At the end of 2015, the total accumulated production of crude ore from openpit and underground mining since the start of mining was 1,566 Mt, with ore reserves of 644 Mt grading 46.3 percent Fe (LKAB, 2016). The deposit defines a steeply dipping tabular body, approximately 6 km long and up to 180 m thick, extending at least 1,500 m below the surface. It is situated in the middle part of the Palaeoproterozoic Kiirunavaara Group of volcanic rocks and follows the contact between a thick pile of trachyandesitic lava and overlying pyroclastics (Martinsson, 2004)."

Jan 1, 2017