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By Mark J. Klein, A. H. Clauer

The Snoek peak induced by solute nitrogen in chromium was studied. A rapid quenching rate is required to maintain nitvogen in solution in sufficient concentrations to be detectable by internal-friction techniques. An expression for the tertninal solubility, c, of nitrogen in weight pevcent is log,,c = -4130/T + 1.05. The diffusion of nitrogen in zhromium determined by internal friction is SNOEK&apos;S theory1 of the stress-induced ordering of interstitial solute elements in the bcc lattice has been used to deduce information on the behavior of interstitials in a number of bcc metals. Under the proper conditions, internal-friction studies of "Snoek peaks" permit a determination of diffu-sivities, solubilities, and precipitation kinetics of interstitial elements. Internal-friction studies of this type have been reviewed by Nowick,&apos; Wert,= Powers and Doyle,4 and others. The behavior of interstitial atoms in Group V-A metals and iron has been rather extensively studied in this way, and results are reasonably self-consistent. However, the study of interstitial elements using internal friction in the Group VI-A metals—tungsten, molybdenum, and chromium—is much less clear. Thus far, internal-friction studies have revealed a peak in tungsten tentatively attributed to carbon5 and a peak in chromium associated with nitrogen. In chromium, Bungardt and Preisendanz6 observed a peak at 180°C for a frequency of -1 cps which they associated with nitrogen. More recently, de Morton7 determined the diffusivity of nitrogen in chromium from studies of a nitrogen peak at 160°c for a frequency of -1 cps and from elastic aftereffect measurements. The objective of this investigation was to study the nitrogen peak in greater detail, to obtain information on the behavior of nitrogen in chromium. This information is of interest because nitrogen is known to have an embrittling effect on chromium. However, efforts to deduce the role played by nitrogen in influencing the mechanical behavior of chromium are handicapped by lack of information on its behavior and distribution in chromium. EXPERIMENTAL PROCEDURES The chromium wires used in these studies were drawn from arc-melted iodide-chromium stock that had been extruded, swaged, and centerless-ground to 0.25 in.-diameter rods. Internal-friction measurements were made in an evacuated torsional pendulum similar to the one described by Kê,8 utilizing wires 0.048 to 0.030 in. in diameter. A series of analyses of the fabricated wires showed that the major impurities were approximately 100 ppm Fe and a combined interstitial content of 50 to 100 ppm C, O, N, and H. A typical interstitial analysis of the wires after processing is 15 ppm C, 2 ppm H, 50 ppm O, and < 5 ppm N. Interstitial concentrations were determined by vacuum-fusion, combustion-conductimetric, and micro-Kjeldahl analyses. In general, vacuum-fusion analysis yielded a lower nitrogen concentration than did micro-Kjeldahl analysis. For consistency, the nitrogen concentrations reported in this investigation were determined by the former method. Heat treatments were carried out by encapsulating the specimens in quartz tubes containing argon. The fabricated wires were annealed at 1150°C for 1 hr to produce uniform recrystallized grain size of about 0.015 mm. Nitrogen and carbon were added to the fabricated wires by encapsulating them in a quartz tube containing ammonia or methane, and annealing them at 1150°C for 48 hr. In some instances, carbon was also introduced by coating the wires with carbon black prior to annealing.

Jan 1, 1965

By S. Martins

The aim of this work is to compare three different results of charge motion in a modified 5ft diameter lab mill and to identify differences and similarities in these results. The lab mill is modified from tumbling a ball charge to tumbling a charge of disks. This modification replicates 2D motion. This 2D condition is measured using an instrumented disk (iDisk) and analysed using a video imaging system. The iDisk is equipped with a 3D accelerometer array and rotation rate sensors. With the help of a video system, some measured quantities are also determined externally. The results of these three predictions or measurements are presented. A discussion is included.

Jan 1, 2014

Good morning. I am very pleased to be invited to present the Opening Address to this inaugural New Zealand Minerals &amp; Mining Conference. It is indeed a pleasure to see so many representatives of this industry, which is so important to New Zealand&apos;s economy, present here today. &nbsp; I extend a warm welcome to all delegates, particularly those from outside New Zealand. To those of you who have travelled from offshore, please closely observe our industry, and do not hesitate to ask Crown Minerals staff here for any further information you may want. I trust you will soon come to the same conclusion that my two following speakers have; that New Zealand is a good investment destination, and further that many of you will decide to invest in New Zealand&apos;s minerals and mining industry. &nbsp; In New Zealand the minerals industry - minerals, coal and petroleum - together constitute an approximate $2.5 billion per year business. In broad terms this is about 3% of our Gross Domestic Product.

Jan 1, 1997

By K. S. Han, M. Yoshimuura, H. Fujita, Y. Sato, S. W. Song

"Film of LlCoO2 as cathode material for rechargeable lithium microbatteries has been fabricated on the platinum metal substrate by electrochemical-hydrothermal method in concentrated LiOH solution at 200 °C as Soft Solution-Processing. The film fabrication has been understood in terms of dissolution of cobalt metal powders and subsequent oxidative deposition on the substrate. The film structure was characterized using scanning electron microscope, X-ray diffraction analysis; X-ray photoelectron spectroscopy and micro-Raman spectroscopy.IntroductionRapid growth of wireless communications and emerging integrated optoelectronic circuits caused the miniaturization· cif electronic devices, thus the demand for high energy density microbatteries as a power source for the microelectronics increases. In this regard, all solid-state lithium microbatteries including LiCoO2 and LlMn2O 4 [l-4], the most promising intercalation cathode material, have been developed. However, major difficulty of .fabrication of a lithium microbattery arose from the preparation of cathode film, according to a· recent report on Rare Metal News [5]. Although many attempts have been made to deposit the cathode films, all those methods are mostly chemical vapor deposiiton (CVD), various evaporation, sputtering techniques and spray pyrolysis. These methods require preparation of bulk cathode materials cir its precursor, then deposition with complicated instruments including high· vacuum system, and even postsynthesis annealing to obtain desire electrochemical 'properties. It is clear that all of these techniques are neither economic nor environmentally friendly. Compared to those methods, film form.ation from an aqueous solution is thought to be simpler and more economical, and requires much· less energy consumption. Our .group has demonstrated the utility of Soft SolutionProcessing [6,7], which is defined as environmentally friendly processing using (aqueous) solutions, to produce films of a variety of functional solid materials. According to the Pourvaix's diagram [8], some metal can be dissolved in an alkaline solution and consequently combined with hydroxyl group or oxygen anion forming metalate or metalite. Cobalt also seemed to form cobaltite, HCoOi in strong alkaline solution in the Pourvaix's pH-potential diagram. Based on this information, it was expected that LiCoO2 could be prepared using the cobalt metal in Li OH solution by Soft Solution-Processing. Recently, we reported the successful single step fabrication of electrochemically active LlCoO2 films on the cobalt metal substrate by hydrothermal methods without any post-synthesis annealing as Soft SolutionProcessing [9,10]. Film formation mechanism could be elucidated by the following evidences. . As expected from Pourvaix's diagram, cobalt metal was dissolved in concentrated LiOH solution forming dissolved cobalt species which was detected by an observation of absorption band in UV-VIS absorption spectrum [10]. Thus the reaction was assumed to be started from dissolution. Time dependent potential of Co electrode exhibited only one-step evolution with 0.6 eV from Co metal to LiCoO2 [10]. Another strong evidence was the finding of LiCoO2 powder precipitates at the bottom of tetlon beaker after the reaction [11]. Based on those experimental findings, it was understood that film is formed by dissolution-precipitation mechanism [9-11]."

Jan 1, 2000

Discussion of the paper of MANUEL EISSLER, presented at the New York meeting, February, 1915, and printed in Bulletin. No. 9.5, November, 1914, pp. 3661 to 2703. J. W. RICHARDS, So. Bethlehem, Pa.-I do not see in the paper a description of the Mabuki hearth as used for ore smelting. I noticed it described for concentrating matte, but I believe the older Japanese process was to use it for-smelting directly, by a pyritic smelting and Bessemerizing all in one operation, in the same simple hearth apparatus. There is a monograph published in German, on Copper-Ore Smelting in the Mabuki Hearth. At Ashio the practice of injecting bituminous coal at the, tuyères is noteworthy. It is very interesting to see two men load little cartridges on the end. of an iron rod with bituminous coal, and push them into the furnace tuyères, and with a piston inject 2 or 3 lb.. of bituminous

Jan 5, 1915

By M. J. Oliver, A. J. Nugent

Hydrogen Peroxide and Caro's Acid (H2so5) were used to treat cyanide containjng effluents. Significant reagent savings were achieved by using Caro's Acid. Weak Acid Dissociable (W.A.D.) cyanides were removed at near stoichiometric levels of Caro's Acid. Hydrogen Peroxide showed poorer efficiency in the presence of W.A.D. cyanide complexes, resulting in higher consumption rates. By using Caro's Acid, reaction catalyst requirements ar(! el.iminatnd, react.ion I.imes significant.I y rnduced and capita] costs for an effluent lreal.ment facility are minimal. The Efflox* Process ut ilisc�s this more efficienl oxidising reagent in a treatment system exhibiting a simple non proprietary control system with minimal peroxygen consumptions.

Jan 1, 1991

By N. Kanari

The kinetics of oxychlorination of MgO by Cl2+O2 was studied in the temperature range of 850 °C - 1025 °C, using thermogravimetric analysis. The effects of C12/02 ratio, gas velocity, temperature and partial pressure of reactive gases on the reaction rate were investigated. The oxychlorination process was characterized by an apparent activation energy of about 214 kJ/mol. The reaction orders with respect to C12+O2. C12 and O2 at 950 °C were about 0.65.0.98, and -0.37, respectively. Some data about oxychlorination kinetics of MgO, Cr2O3, and MgCr2O4 contained in chromite were compared. Efficiency of using oxychlorination for the removal of iron oxides contained in magnesia was demonstrated.

Jan 1, 1999

By A. T. Coumbe

The first survey 3/ covering sales of liquefied petroleum gases was made in 1930 by the Bureau of Mines, which at the time was under the United States Department of Commerce. This original canvass covered national totals for 1922 through 1929, and most of the supply came from natural gasoline plants. The 1930 report showed approximate totals for butane and propane and for butane-propane mixtures and pentane grouped together. No attempt was made to breakdown the national sales by various uses until 1931, when the quantities for domestic or household consumption, gas manufacturing, and industrial requirements, including miscellaneous uses were indicated. As the market for these liquid petroleum gases expanded and as new uses came into importance, their respective quantities were shown separately in the annual survey. Sales for internal-combustion engine fuel and for raw material for chemical plants were first taken out of the industrial total in 1936. During World War II liquefied petroleum gases became important as feed stock diverted to synthetic rubber plants, and consequently the survey was broadened to cover this particular demand, beginning in 1944. Pentane was dropped from the survey after 1943, as, being liquid at atmospheric pressure, it is not considered as one of the liquefied petroleum gases and furthermore, the quantity reported made up less than 1 percent of the total sales. Thirteen producing companies reported to the Bureau in the first survey made in 1930, and in the 1952 canvass about 130 producers--petroleum refiners and natural gasoline companies--and about 1,300 dealers cooperated by filing schedules showing a breakdown of their sales. Their 1952 deliveries of approximately 4.5 billion gallons of liquefied petroleum gases were equivalent to about 3.4 billion gallons of gasoline or 3.1 billion gallons of distillate fuel oil.

Jan 1, 1954

By M. H. Kline, Wing G. Agew

"INTRODUCTION The Watson tract was first prospected in 1908, and ore consisting of concretionary psilomelane and wad was found in the bedded residual clays. A small mill using a log washer and jigs was constructed for concentrating the ores -on the bank of Mudhole Run, and it is reported that a few wagon¬loads of ore were shipped via the Norfolk & Western Railway. The operation was of short duration.During World War I, the area was seriously studied by the Federal Geological Survey and Virginia Geological Survey. The Virginia Geological Survey, in Bulletin 173/ reporting the work, lists the property among the few recommended for further exploration.When the shortage of manganese ores in the United States became imminent, the Bureau of Mines was authorized by the 76th Congress, under the Strategic Materials Act, to prospect and explore for manganese. Upon the recommendation of the Federal Geological Survey, a project to undertake this work was started at the old Watson mine in January 1941 and continued until August of the same year."

Apr 1, 1948

By J. L. Furtney, C. Fairhurst

"Although global mineral resources are considered to be adequate to meet the needs of a rapidly growing world population, the United States is becoming increasingly dependent on imports. This could have implications for both the economy and national security. The US is a country with a strong tradition of leadership in science and technology. Impressive advances in autonomous underground mining systems reduce the adverse effects of heat and humidity in deep mines and focus renewed attention on ground control. Developments in computing power open opportunities to develop improved understanding of the important role of discontinuities (faults and fracture systems) and more effective design of deep excavations. Establishment of mining R&D Centers at leading US research universities, jointly funded by industry and US federal agencies is recommended as an effective step for the nation to remain an influential partner in world mining. INTRODUCTION. “None of the arts is older than agriculture, but that of metals is no less ancient.. . for no mortal man ever tilled a field without implements. If we remove metals from the service of man, all methods of protecting and sustaining health and more carefully preserving the course of life are done away with.” Agricola (1558)i Homo sapiens, generally acknowledged as the species from which modern Man has evolved, is considered to have originated in Swaziland some 100,000-200,000 years ago. Evidence of use of minerals in that region has been dated to earlier than 40,000 BC.ii Today, a large fraction of the elements of the Periodic Table are derived from minerals, and finding new applications in development of innovative technologies. Agricola’s comments are as applicable today as ever.iii Metals such as copper, tin, lead, iron and aluminum were mined and smelted several thousands of years BC. It was not until the Industrial Revolution, started in the latter half of the 17th Century in Northern England, where coal was available as an energy source, and iron as the basis for fabricating machinery, that dramatic change to society began to occur. Human toil was replaced by far more powerful machines. Rural communities migrated to work in factories in urban areas. Rapid transportation over long distances became possible, leading eventually to the world of today. The change spread to other parts of the world, bringing wealth and power. Although now well established in some regions, the Revolution has still to arrive in many other parts of the world. This can be seen in Figure 1, which shows the relative wealth, or ‘Standard of Living’ as measured by the GDP/capita, of regions around the world. Regions such as North America, Europe, and Australasia iv are seen to have the highest standard. Thanks to today’s global communications systems, regions with relatively low GDP/capita are well aware of ‘how others live’ – and eager to emulate them."

Jan 1, 2018

By Y. Rao, Y. Huang, G. Wang, W. Liu

The properties and deterioration in strength of cemented tailings backfill (CTB )in the underground acidic environment under oxidizing conditions were studied. X-ray diffraction analysis and scanning electron microscopy of the surface of the CTB was carried out, and the sulphuric acid corrosion mechanism elucidated. The properties tested included compressive strength, elastic modulus, cohesion, internal friction angle, variation in the hydrogen ion concentration, and stress-strain relationship in different corrosion periods. The damage model of the CTB was established considering the effects of parameters such as corrosion time and strain on the damage evolution. It was found that the compressive strength, elastic modulus, cohesion (binder effect), and internal friction angle increased at first and then decreased with exposure time. In the long term, the peak stress decreased with corrosion time while the peak strain increased; elastic modulus, and deformation modulus also decreased. The damage caused by corrosion and by load were related by means of a mathematical model, which revealed the relationships between sulphuric attack, load, and damage to backfill in complex underground environments. During corrosion, the expansion of gypsum and ettringite caused microfractures in the CTB. With increasing corrosion time, micro-cracks developed and proliferated. The mechanism of corrosion damage was found to be the dissolution of hydrogen ions and a sulphate ion reaction that produces an expansive substance, resulting in deterioration of the strength of CTB.

Jun 1, 2021

By George A. Mealey

Caving mining methods that are based on a planned caving of rock above and/or at times surrounding the material being mined can be classified in three broad categories: longwall mining, sublevel caving, and block caving. Each of the three methods involves a distinct technology as well as art of operation. Each requires a relatively large, regular, and predictable ore body. As a rule, the effect of mining results in some form of impact or change on the surface. Operationally, underground caving methods are characterized by high productivity as well as a high percentage of extraction of the mineral being mined. A key element for the productivity of this form of mining is the ability to standardize the various elements of work taking place underground. Therefore, work-men may perform a specialized role rather than function as all-around miners. Further, the nature of the mining methods lend them to a high level of mechanization. Operations and manpower can be centralized into a relatively small area where supervision can be concentrated and therefore be more effective. Productivity as well as safety benefits thereby. The caving method is unique in that the exploitation openings are deliberately destroyed by the process of mining. Rock mechanics principles focus on the ensurance and the propagation of the cave as well as the continuance of the mine openings designed to extract the broken ore. As a rule, production operations are designed to maintain a steady, continuous flow of ore from the extraction areas. This steady flow rather than an intermittent flow tends to promote good caving action as well as reduce hangups.

Jan 1, 2008

By Michael J. Sapko, Eric S. Weiss, Kenneth L. Cashdollar

A fundamental safety research area for the National Institute for Occupational Safety and Health (NIOSH) is to eliminate the occurrence of coal mine explosions or to mitigate their effects. One approach is to develop and evaluate new and innovative seal designs that provide increased explosion protection for mining personnel. The NIOSH Pittsburgh Research Laboratory (PRL) cooperated with HeiTech Corp. of Virginia, Barclay Mowlem Construction Ltd. of Queensland, Australia, and the Mine Safety and Health Administration (MSHA) in three separate research programs to evaluate the strength characteristics and air leakage resistance of numerous innovative seal designs and ventilation control structures for use in underground coal mines. For each phase of the program, various full-scale seals, stoppings, and an overcast design were constructed in PRL&apos;s Lake Lynn Experimental Mine near Fairchance, Fayette County, PA. The seals and stoppings were built in crosscuts and were subjected to explosions to evaluate their strengths. Four pumpable cementitious seal designs ranging in thickness from 610 to 915 mm (24 to 36 in) were evaluated in the first cost-reimbursable research program with HeiTech Corp. A simple wooden framework with brattice liner was used as a form to contain the cementitious slurry during the curing period. As the seal designs decreased in thickness, higher compressive strength cementitious grout was used. All four seals withstood an explosion pressure pulse of at least 138 kPa (20 psi) while maintaining acceptable air leakage resistance. In the second cost-reimbursable research program with Barclay Mowlem Construction Ltd. of Australia, several innovative seal and stopping designs and an overcast design were evaluated. Each of the seal designs and the overcast side and wing walls used one or more air-inflated vinyl bladder assemblies anchored to the mine roof and hitched into the ribs and floor. The air within these bladders was displaced with a high-strength cementitious grout. The overcast deck consisted of a 200-mm (&apos;7.8-in) thick reinforced cementitious slab. This was the first time that an overcast structure had been explosion tested under full-scale conditions. All of the seals, stoppings, and overcast design passed the air leakage tests before being subjected to a series of explosions with static pressure pulses ranging from 14 to 475 kPa (2 tab 69 psi). Instrumentation measured seal and overcast wall displacement as a function of time. The 450-mm (1 7.7-in) thick seal in the 2.8-m(9-ft) high third crosscut withstood an explosion pressure of 170 kPa (25 psi), but failed during a later test, which generated a peak static pressure of 475 kPa (69 psi) at the seal location. A similar 450-mm-thick seal in the 2.1-m (7-ft) high second crosscut withstood three explosion tests, which generated peak static pressures of 195, 205, and 370 kPa (28, 30, and 54 psi) at the seal location. Next, the overcast design withstood four explosions, which generated static overpressures ranging from 16 to 47 kPa (2.3 to 6.8 psi). A third program at the request of MSHA evaluated the effectiveness of using pressurized grout bags (Packsetter bags) along the mine roof and ribs in lieu of floor and rib hitching for a standard-type solid- concrete-block seal. This program was initiated to address an urlusual geological mining condition encountered when building seals in entries where required rib hitching is not a viable option due to soft friable coal. Results showed that the use of these quick-setting grout-filled Packsetter bags pressurized internally to 300 kPa (44 psi) not only provides a seal that can withstand a 138-kPa static pressure explosion, but also provides a sealing option where rib hitching is not possible.

Jan 1, 2003

By Baafi EY, Chatterjee PK

The quality of mine planning decisions ultimately depends on reliable estimates of the characteristics of the orebody. The quant- ifiable factors such as grades or thickness can be estimated from field data gathered from outcrops or exploratory drillholes. Since outcrop data is necessarily limited to the periphery of a deposit, extensive drilling generally is required. This paper outlines a method for selecting the number and location of additional exploratory boreholes using an iterative procedure based on a mathematical optimization concept called fixed point theory. The method is illustrated through its application to an exploratory drilling program for a coal mine where optimized locations gave a lower estimate of regional and block variances than a manual Choice.

Jan 1, 1986

By Thomas Fraser

IN a Nation-wide appraisal of coking-coal reserves and of the feasibility of expanding them by upgrading marginal coals, it is natural that the Pittsburgh region of Pennsylvania should be considered first. Here, where the American iron and steel industry started, the Pittsburgh coal bed is of paramount importance. The use of coke in iron blast furnaces is said to have begun with the discovery that good blast-furnace fuel could readily be made by a simple method of coking Pittsburgh coal. To the present time, the prosperity of the steel industry has depended largely on utilization of this great coal reserve and the cheap transportation afforded by the Monongahela River system. OBJECT AND SCOPE OF INVESTIGATION The initial project in the study of upgrading marginal coking coals was laid out in this area, which contains large reserves of Pittsburgh coal contiguous to the Monongahela and its navigable tributaries. Much of the Pittsburgh coal remaining here is known to have a high sulfur content. The problem of reducing the sulfur to meet metallurgical requirements already has received much attention, and it is considered to be one of the most difficult technologic problems in the field of coal washing.

Jan 1, 1950

By A. Renton Amell

The rate of dissolution of U02 was measured in acid solutions similar to those used for in situ leaching, with S04 of 10-1.82 to 10-4 M, Fe(III) of 10-2 to 10-4 M and pH&apos;s of 1.1 to 2.3. The dependence of dissolution rate on pH was small and inconsistent, probably reflecting the combined effects of a very weakly polar oxidizing complex, probably FeSO4+, and a nearly neutral U02 surface. Differences in the state of the U02 surface may explain this variability as well as contrasts between these results and results reported in other work. Changing either S04 or Fe(III) concentrations significantly affects dissolution rates. Increasing low sulfate concentrations in solutions containing 10 2 M Fe(III) at pH 2 results in formation of FeSO4+. In such solutions, rates increased with (S04)/(Fe(III)) up to 1:30, thereby indicating that the oxidation of U02 by FeSO4 is more rapid than by Fe3+. However, the dissolution rate decreased at higher (SO4)/ (Fe(III)), due either to sorption of SO42- on the UO2 surface or to formation of other less reactive sulfate complexes such as Fe(S04)2 or FeHSO4+ However, Fe(III) concentration is the dominant factor in determining solution rates. The rate was directly proportional to ferric iron concentration, indicating that the rate-determining step of the dissolution reaction is a single-electron oxidation by a ferric complex. Dissolution rates were lower in solutions of 0.1 and 1.0% H202 (0.029 and 0.29 M) than at similar concentrations of ferric iron because of formation of an insoluble surface coating of uranium peroxide, UO4?4H20. This phase may limit the value of hydrogen peroxide as an oxidant in lixiviants, not only by its very low solubility, but perhaps also by filling pores and reducing permeability in the ore body.

Jan 1, 1978

By Jerry Dolph

Hecla Mining&apos;s Lucky Friday Mine, located beneath the town of Mullan, ID, has been shaken since the 1960s by many deep underground rock bursts. The largest rock burst carried a magnitude of 3.5 on the Richter Scale. It occurred in 1969 when all of the stopes on a level approached an upper level at the same elevation. After that, a stair-step pattern was used to give the mine&apos;s levels more of an "arch." The article is an account of one of the more ferocious bursts to hit the miners of the Lucky Friday. I say "miners" instead of "mine" because I was there and it was a very personal experience for me. I had been working at the Lucky Friday for six years. During that time, I had heard and felt thousands of air blasts. In fact, in the early spring of 1986, the mine was experiencing as many as 1000 air blasts an hour, of different intensi¬ties, of course. Most of them sounded like popcorn popping. There were also a few bumps and occasionally a real boomer. That day did not seem any different

Jan 1, 1994

By P. O. Osifo, K. Premlall, X. Goso, R. H. Matjie, M. R. Mulaudzi, J. R. Bunt, K. Mphahlele

This study investigates the transformation of pyrolytic spent tyre-derived char and crumb rubber into high-performance activated carbon chars for industrial wastewater remediation. Utilising an in-house macro-thermogravimetric analysis system under an argon atmosphere, spent tyre-derived activated carbon char were synthesised via physical temperature activation and aqua regia demineralisation. Comprehensive characterisation using x-ray diffraction, Raman spectroscopy, and scanning electron microscopy, revealed a predominantly amorphous structure with nanoscale crystallites (~1 nm) and active surface functional groups. Proximate analysis confirmed that both crumb rubber and leached tyre crumb rubber with aqua regia derivatives achieved favourable compositions (ash ≈ 9.6%; fixed carbon ≈ 84%), comparable to commercial activated carbon (AC). At an optimal activation temperature of 850°C, the char of tyre crumb leached with aqua regia variant exhibited a significant surface area of 300 m²/g. Crucially, the tyre crumb char produced at 850°C variant developed a pore volume of 0.8 cm³/g—effectively doubling that of commercial activated carbon (0.4 cm³/g)—facilitating the sequestration of large organic molecules. In application tests using high-strength starch wastewater, char of tyre crumb leached with aqua regia and tyre crumb char, both produced at 850°C, achieved total organic carbon removal efficiencies of 60% and 50%, respectively, bridging the performance gap between waste-derived and commercial adsorbents. These findings validate waste tyres as a viable, low-cost precursor for industrial-grade adsorbents, offering a sustainable circular economy route for tyre valorisation and reduced industrial disposal costs. Future research will focus on kinetic modelling and the recovery of zinc from spent tyre-derived activated carbon char residues.

Mar 30, 2026

By Arnaud Colson

1 Good morning ladies and gentlemen. Let me first thank you for welcoming me to this international congress. I?ll have the pleasure to explain to you how the Lafarge group works on its quarry rehabilitation. I will deal with the way quarry rehabilitation has affected all branches of the group trough a global approach. 2 Quarries often are a subject of controversy dividing those are for and those who are against. My purpose is rather to examine where factors of progress lay and how in a quarry such as Lafarge we can include quarry rehabilitation, which is so fundamental dimension of our process. 3 - 4 As these two photos of French quarry show taking into account the environment in the quarry industry has been a recent preoccupation. In less than a century rehabilitation has a dramatically evolved in a positive way. Consequently our group integrate an ecological dimension in its activity. It?s an ethical question as well as a personal view of our role as a responsible industrial group. 5 My presentation is built around 4 points: I?ll begin by explaining why it?s our responsibility to rehabilitate quarries. I?ll go on to fill you in on the method of the project. After that I?ll outline the expected results. Finally I?ll talk about the rest of the project and the way we can ensure this know how.

Jan 1, 2002

By Darling Elías Montoya

El presente trabajo señala la importancia de la cuenca del Marañón en tanto representa un ambiente idóneo de deposición aurífera para el ámbito nacional. La cuenca se encuentra situada entre los centros poblados de Borja-Saramiriza-Puerto América de Madre de Dios, cuyas condiciones desarrollan posibilidades de deposición de oro aluvial. El estudio prospectivo fue empleado por personal técnico de la gerencia de exploraciones de Centromin Perú.S.A en el que obtuvieron 26 muestras referenciales, encontrando 100 000 hectáreas de interés prospectivo por oro fluvial.

Apr 1, 1991