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By Jamil M. Khalifeh, Shadia J. Ikhmayies, Bothina A. Hamad

"We computed the optical properties of the cubic niobium nitride (o-NbN) compound using the full potential linearized augmented plane wave (FL-LAPW) method within density functional theory (DFT). The complex dielectric function and optical constants, such as optical absorption coefficient, refractive index, extinction coefficient, energy-loss spectrum, and reflectivity, are all calculated and compared with experimental results. The behavior of the computed quantities is similar to that obtained experimentally, but the optical positions are shifted to lower energies. This shift was related to the strong interband transitions, which are located at energies higher than 5 eV for NbN- as they are for IV B transition-metal mononitrides- and they appear in the computed spectra and not in the experimental spectra. These interband transitions simply shift the position of the reflectivity edge or the screened plasma frequency to the longer wavelength side.IntroductionIn recent years, NbN, as a transition metal nitride, has become a very popular material due to its high hardness, melting point, wear resistance, chemical inertness and temperature stability, which makes it suitable for use as emission cathodes in microelectronics and sensors, optical films and micro-mechanics etc [l]. Niobium nitride has long been known as highly polymorphic material, for which several crystalline structures have been reported in the literature [2]. These structures include the well known super-conducting rock-salt (Fm-3m, or Bl) structure (o-NbN), the hexagonal structure with space group p63/mmc and prototype Fe2N (18fuN), the hexagonalstructure with space group p63/mmc and prototype NiAs ~-NbN) and others.There has been a lot of computational studies for the structural and electronic properties ofNbN [3, 4-7], but according to our knowledge there is not any computational work that has been devoted to study the optical properties of this transition metal compound. At the same time a number of authors had performed experimental work in this direction. For example, Xin-kang et. al [l] studied the microstructure and optical properties of magnetron sputtered NbN thin films. Torche et. al [8] studied the composition, structure, electrical and optical properties of nonstoichiometric niobium nitrides. Newport et. al [9] investigated the reflection and transmission spectra of cubic niobium nitride films, and Tanabe et. al [10] had investigated the optical parameters and reflectivity of reactively sputtered NbN thin films by using in situ ellipsometry."

Jan 1, 2013

The reduction of titanium tetrachloride to trichloride can be achieved by employing hydrogen and electric arcs. It is possible to produce melts containing up to 50% TiCk in the eutectic mixture of LiCl/KCl by striking a D.C. arc at the surface in the presence of hydrogen and TiCl. vapour. If the electrode IS made to just penetrate the surface of the salt mixture, a hot zone results from the' high resistance contact with both lower chlorides and sintered titanium may be produced. The sintered metal forms just below the melt surface while the trichloride forms at the gaslIiquid junction.The "hotspot cathode" appears to offer a solution to the problem of producing coherent deposits as the spong'e metal can 'be continuously withdrawn in a similar manner to the "calcium process".INTRODUCTIONConsiderable interest has been shown for some years in the possible development of a cheap electrolytic process for the extraction of titanium metal, since a method using simple materials and cheap electric power would materially reduce the cost of production. Even when cheap starting materials are used, however, there exist several general difficulties in the operation of plant which both limit the speed of production and increase the cost of the product. It happens that most of the techniques so far tried produce a powder as cathodic deposit, and when this is the case the following difficulties arise:1. The whole contents of the bath must be treated with solvent in order to extract the 'metal powder which may itself tend to oxidise, and thus become contaminated.2. Fine metal powders, which often contain residual entrained salts, are less easy to consolidate by arcmelting than metal sponge.

Jan 1, 1956

Enhancement of Energy Efficiency in Fine Grinding of Copper Sulfide Minerals Using a Pilot-Scale Stirred Media Mill - IsaMill The mineral liberation size of run of mine ores has dramatically reduced over recent years. As a result, the demand for fine grinding which is the most energy-intensive form of grinding has markedly increased in the minerals industry. Furthermore, the fine grinding costs increase exponentially with decreasing product particle size. As a result of the increased energy requirement for fine grinding, it is desirable to optimise fine grinding processes such as stirred media milling (ie IsaMill) to enhance energy efficiency, throughput and the product fineness. In the present study, the influence of slurry rheology, grinding media type and grinding media-to-feed size ratio on energy efficiency in a pilot-scale IsaMill was investigated under certain industrially relevant pulp processing conditions. It was shown that a critical rheological state existed, below which the energy required to achieve an 80 per cent passing (ie P80) 20 ¦m product size was unaffected by shear rheology (ie apparent viscosity and shear yield stress) whilst above which the grinding energy required increased dramatically with increasing shear rheology. Colorado River sand (3.35 mm) showed higher energy efficiency than MT1 ceramic media (2.5 mm) for a target P80 of 20 ¦m in the solids concentration range of 38 to 55 per cent by weight, but the former experienced more than four times the wear rate of the later. The high wear rate of the Colorado River sand may be due to its much lower hardness. For feeds with an 80 per cent passing (ie F80) 70 to 110 ¦m, 2.0 or 2.5 mm MT1 media appeared to be more energy efficient than 3.5 mm MT1 media whilst a media-to-feed size ratio of 41 to 53 is applicable for ~50 ¦m (ie F80) feeds for efficient grinding.

Sep 13, 2010

By J. P. Hammond, C. J. McHargue

THERE have been no publications on the wire texture, on the cold-rolled sheet texture, nor on the recrystallized sheet texture of vanadium. Since it has a body-centered cubic structure, it would be expected to show strongly preferred orientations such as are found in iron' and molybdenum.' The wire textures of body-centered cubic iron,3 tungsten," molybdenum,5 antalum,6 iobium,6 and brass6 have been found to have [110] directions lying parallel to the wire axis. Wires of iron,' containing 1.95 pct V or 1.95 pct Si,7 and steel8 retain their texture upon recrystallization. Molybdenum9 and tungsttln' wires retain their texture after recrystallization at low temperatures. A [loo] recrystallization texture has been reported for mo1ybdenum9 and for a Fe-Ni alloy (53 atomic pct Ni).10 The cold-rolled sheet texture for iron,' mild steel," and molybdenum chiefly one in which the [110] directions lie parallel to the rolling direction and the (100) planes lie parallel to the rolling plane with a deviation from this position chiefly about the rolling direction as an axis. This paper presents the cold-rolled and the re-crystallized wire textures, and the cold-rolled and the recrystallized sheet textures for vanadium. The results show that the textures in vanadium are not significantly different from those reported for other body-centered cubic metals. The vanadium used in this investigation was the so-called "ductile" vanadium which has a nominal composition within the following limits:12 0, 0.05 to 0.12 pct; H, 0.001 to 0.004; N, 0.02 to 0.04; C, 0.03 to 0.07; and V, 99.8 to 99.9. The wires were formed by rolling annealed rods of 0.280 in. diam to 0.028 in., a reduction in diameter of 90 pct. The wires were then electrolytically etched to 0.005 in. diam and used as such for specimens. Annealed sheet was reduced 95 pct in thickness from 0.100 to 0.005 in. with a two-high, 4-in. diam mill using reductions no greater than 10 pct per pass. In order to avoid temperature effects, the sheet was allowed to cool between passes. X-ray specimens were made in the form of posts from the sheet. The sheet was mounted in a fixture and the edges were polished using metallographic technique. Each edge was alternately polished and etched during the last stages in order that all worked material would be removed. These post specimens were approximately square in cross-section. The specimens to be recrystallized were wrapped in tantalum foil, sealed in evacuated quartz tubes, and annealed at 1600°F. The X-ray data were obtained from transmission shots made with a 0.030 in. pinhole camera, and molybdenum radiation with a zirconium filter inserted between the specimen and film. The grain size was sufficiently small in both the cold-worked and recrystallized material to give satisfactory results with the specimens stationary. In order for the wire texture to be determined, transmission X-ray patterns were taken with the

Jan 1, 1953

By S Ellis, J McMullen, M Habner

A new leaching regime was implemented at Kalgoorlie Consolidated Gold MinesÆ (KCGM) Gidji plant on a cyanide leach of ultra-fine ground sulfide concentrate. High lime concentration and lead nitrate were used to overcome the refractoriness of the fine sulfides (high reactivity of fine sulfides with the presence of gold tellurides). The leach pretreatment stage was shown to be detrimental and was shut down. Lime titration was introduced as part of the process control. It was shown that the leach could be performed at low dissolved oxygen, (ie 3 - 5 ppm) to avoid sulfide oxidation and the associated high cyanide and lime consumption. Plant results showed reduced cyanide consumption (40 per cent) and an accelerated leaching rate, whereby most of the gold was dissolved in 24 hours compared to 72 hours used previously. Similar work was performed at KCGMÆs Fimiston plant, which leached a combined ultra-fine ground sulfide concentrate along with the slimes fraction from hydrocycloning the bulk flotation concentrate. The use of lead nitrate, high lime and carbon-in-leach generated a faster leaching rate and minimised adsorption of gold on fine pyrite particles. The grind, previously controlled with a P80, was replaced by a P98 to give a better operational indication of top size hydrocyclone performance. Before the implementation of the changes, average leach residues for slimes and UFG were respectively 4.0 g/t and 5.5 g/t. With the modifications to the leaching regime, average leach residues were lower by 1.5 - 2.0 g/t. Whilst significant improvements have been demonstrated, further work is progressing at KCGM to further reduce ultra-fine concentrate leach tail grades, and also to improve the understanding of concentrate refractoriness and the factors responsible for differences between laboratory and plant leach results. Estimated profits since the implementation of the new approach are in the range of $A3.5 million per year.

Jan 1, 2005

Commercial or potentially commercial deposits of coal occur in Australia in strata ranging in age from Permian to Tertiary. The coals of each period tend to show a community of petrographic character and significant differences as compared with coals of other ages. In particular- many of the Permian coals are unusually rich in inertinite whereas the Jurassic and Tertiary coals are typically very rich in vitrinite. The majority of the coals show evidence of deposition in environments subject to relatively minor marine influence. Except for some Tertiary and Permian coals the content of mineral matter tends to be high. Outcrops of coals of bituminous rank appear to be largely restricted to the eastern margin of the Australian continent. In this region vertical rank gradients are generally higher than in the other sedimentary basins and uplift and the removal of cover has occurred to a greater extent. To the west of the Tasman geosyncline, coal of bituminous rank generally occurs at considerable depths (usually in excess of 1 km and in some areas only at depths of over 2 kms), and in most areas coals at shallow depth are of sub-bituminous or brown coal rank. The controls of the distribution of coal type and rank have considerable economic significance and the unusual characteristics of Australian coals, especially with respect to coal type, make the direct application of overseas technology to Australian coals inappropriate.

Jan 1, 1975

By Joseph Jensen

FROM Aug. 31, 1937, until Apr. 30, 1939, there were 40,872,610 bbl. of oil run to storage in California; from Apr. 30, 1939, to Aug. 31 of the same year 5,512,912 bbl. were withdrawn from storage. But from Aug. 31, 1937, to Aug. 31, 1939, the number of producing wells in the state has increased from 17,706, with a potential production of 1,323,202 bbl., to 18,910, with a potential of 2,302,282 bbl. Thus, in a period of two years, during the first 20 months stocks increased over 1/3 and during the following four months stocks decreased 1/30. In the same two years the number of productive wells increased 1/15 and potential increased 3/4. Undoubtedly, the large increase in stocks created the pressure that caused the reduction in stocks that followed; yet this has come about in spite of the larger number of wells and higher potential. Cause of the change was the adoption on May 17, 1939, by the Central Committee of California Oil Producers of a uniform method of oil curtail-ment for all wells throughout the state. Acceptance of the method in the four months following adoption by practically all fields in California indicates that producers generally are convinced of its merit and fairness. True, some operators still overproduce, but the restraint practiced by the remainder of the industry has been sufficient to turn a situation headed for chaos into one of reasonable stability. Credit for this change goes to the industry itself, because it has all been accomplished under voluntary oil curtailment.

Jan 1, 1940

By W. W. Adams

"Fatal accidents at coal mines throughout the United States killed 234 employees during January 1924, according to reports from State mine inspectors to the Bureau of Mines of the Department of the Interior, Included in the number of fatalities are 68 deaths caused by two explosions during the month, one explosion occurring in a mine at Johnson City, Ill., and causing 32 deaths, and the other in a mine at Shanktown, Pa., and causing 36 deaths. The fatality rate for the month was 3.94 per million tons, based on a production of 59,435,000 tons of coals In January 1923 the fatality rate was 3.52, based on 206 deaths and an output of 58,458,000 tons.Bituminous mines in all States reported 202 fatal accidents, the production being 51,170,000 tons., and the fatality rate being 3.92, as compared with 3.28 for January last year, For the anthracite mines in Pennsylvania, the reports covered 32 fatalities, which, on the month's output of 7,955,000 tons, indicated a fatality rate of 4.02 per million tons, as against 4.89 for January 1923.As compared with January 1923, the reports for January of the present year indicated lower fatality rates per million tons for all of the main causes of accidents except explosions. For falls of roof and coal, the fatality rate per million tons declined from 1.85 in January 1923 to 1,68 in January 1924; for haulage accidents the rate declined from 0.62 to 0.42; for explosives, from 0.19 to 0.12; for electricity, from 0.12 to 0.07. The rate for explosions increased from 0.21 to 1,31 per million tons. -- Reports of Investigations, Department of the Interior, Bureau of Mines."

Feb 1, 1924

Background The annual awards, which have been given by the US National Committee for Rock Mechanics since its inception in 1969, recognize out- standing research in rock mechanics. Such recognition has always been accompanied by a plaque or certificate for the winners and a presentation at the symposium awards banquet. Starting this year, the US National Committee will give the winners even more recognition and allow the rock mechanics community to benefit from the papers by publishing abstracts of the work in the proceedings of the 25th US Symposium on Rock Mechanics and in various society journals and news letters. "We hope this will stimulate the production of more research papers," said William R. Judd, former chairman on the subpanel of awards. "It's beneficial for researchers to have their work published as an award paper." There are four categories of awards: Basic Research, Applied Research, Case History, and Student Masters' Thesis. Approximately ten papers are nominated annually for each category; however, in some years awards are not made in all four categories. For instance, there were not enough case history nominations in 1983 for an award, but there were two equally outstanding recipients of the award for applied research. The winners of the 1983 research awards reflect the wide variety of professions involved with rock mechanics. They are introduced on the following pages by category, and accompanied by an abstract of the paper

Jan 1, 1984

By W. L. Saunders

When work was begun in September, 1910, on the rock excavation for the foundation of the gigantic dam at Valhalla, N. Y., which is to convert Kensico lake into an important storage reservoir of the Catskill Aqueduct system, one of the first steps taken by the contractor, H. S. Kerbaugh, Inc., was the development of a quarry to supply the stone needed in the

Jan 1, 1915

By C. R. Van Hise

Introduction.............29 The Three Zones of the Lithosphere ..30 Zone of fracture............31 Zone of flowage............ 31 Factors influencing depth at which flowage occurs.. 32 Zone of combined fracture and flowage.. 33 The Water-Content and Openings in Rocks....36 Condition of rater in the zone of fracture.. 36 The openings in rocks...........38 Size and number of openings..... 40 Ore-deposits derived from zone of fracture..45 The source of underground water......... . 47 The cause of the flowage of underground water..47 Belts of underground circulation.. 51 Upper belt of underground circulation.. 51 Lower belt of underground circulation.. .... .52 Capacity of water for work in the lower belt of underground circulation........... 53 Movementsof water in the lower belt of underground circulation. 54 The preferential use by water of large channels.. 60 Physico-Chemical Principles Controlling the Work of Under ground Waters..........62 Chemical action............63 Underground aqueous solutions..64 The relations of solution and temperature..... 65 The relations of solution and pressure..66 Precipitation........... 67 Precipitation by change in temperature..68 Precipitation by change in pressure..69 Precipitation by reactions between aqueous solutions.. . 69 Precipitation by reactions between liquid solutions and solids. 70 Precipitation by reactions between gases and solutions. and solids............71 The General Geological work of Underground Waters.. . 71 Division of the zone of fracture into a belt of weathering and a belt of cementation............72

Jan 1, 1901

By John G. H. Crump, E. W. Owen, Peter P. Gregory

.Although oil Production in West Texas in 1939 reached the highest figure for any year since the inauguration of proration, drilling activity continued in the decline that had commerlced the previous year. Production totaled 79,469,341s bbl. of oil during 1939 as compared with 71,257,541s bbl. in 1938 and 75,743,000 in 1937. The number of wells completed in 1939 was 1850, compared with 2045 in 1938 and 2806 ill 1937. Several factors combined to cause the decrease in drilling activity, principally the contiriued increase in the length of time required to obtain a return of invcstment and the scarcity of important new discoveries during the past two years. Of the 1850 completions 1638 resulted in oil wells, 4 were gas wells, 168 were dry holes and 40 were abandoned locations; 1990 new locations were made during the year. The ratio of dry holes to producing wells completed was one dry hole to each 9.75 oil wells, compared with one dry hole to each 7.48 oil wells completed during 1938. This large decrease in dry holes was due to a marked decline in the number of wildcat wells drilled, there having been only 120 wildcat completions during 1939. In addition to the lessened exploration work, the deeline' in activity was largely accounted for by the slowing up of operations in the older pools of Ector, Howard and Winkler Counties. Ector County, which had led West Tcxas in 1938 with 622 new oil wells, furnished only 485 producers in 1939, but was still the leader for the West Texas district. The largest gain in activity was in Yoakum County, whew 350 oil wells were completed in the Denver-Wasson field against 152 during 1938. Most of the older oil fields have been almost completely drilled up, only a few new producers still being completed from time to time in

Jan 1, 1940

By E. W. Owen, John G. H. Crump, Peter P. Gregory

.Although oil Production in West Texas in 1939 reached the highest figure for any year since the inauguration of proration, drilling activity continued in the decline that had commerlced the previous year. Production totaled 79,469,341s bbl. of oil during 1939 as compared with 71,257,541s bbl. in 1938 and 75,743,000 in 1937. The number of wells completed in 1939 was 1850, compared with 2045 in 1938 and 2806 ill 1937. Several factors combined to cause the decrease in drilling activity, principally the contiriued increase in the length of time required to obtain a return of invcstment and the scarcity of important new discoveries during the past two years. Of the 1850 completions 1638 resulted in oil wells, 4 were gas wells, 168 were dry holes and 40 were abandoned locations; 1990 new locations were made during the year. The ratio of dry holes to producing wells completed was one dry hole to each 9.75 oil wells, compared with one dry hole to each 7.48 oil wells completed during 1938. This large decrease in dry holes was due to a marked decline in the number of wildcat wells drilled, there having been only 120 wildcat completions during 1939. In addition to the lessened exploration work, the deeline' in activity was largely accounted for by the slowing up of operations in the older pools of Ector, Howard and Winkler Counties. Ector County, which had led West Tcxas in 1938 with 622 new oil wells, furnished only 485 producers in 1939, but was still the leader for the West Texas district. The largest gain in activity was in Yoakum County, whew 350 oil wells were completed in the Denver-Wasson field against 152 during 1938. Most of the older oil fields have been almost completely drilled up, only a few new producers still being completed from time to time in

Jan 1, 1940

record with the Royal Flying Corps was considered a remarkable one, for he was at the front within two months of the date on which he was granted a commission, during which interval he took the prescribed technical course at Oxford, and aviation training at Netheravon and Bristol. On Sept. 14, 1916, he took his first flight over the German lines, when his engine stalled and he had to volplane down, fortunately landing on the French side of the lines. On Sept. 16, he went over the lines with six others, and not returning immediately with the others, was lost. He tried to make for the sea and come back following the course of a river, but when he did descend he found that he was 60 miles west of Paris and 100 miles south of his lines. He flew over to Paris and stayed there for the night, going back to his squadron the next morning. Then on Oct. 4, he was sent up at night for the first time, and in making a landing he passed the flares just as he struck the ground, which put him in total darkness. He struck something and his machine turned a complete somersault, which accident put him in the hospital for ten days. In December, 1916, he left the 21st Squadron and was transferred to the 24th, as the 21st was made an Artillery Squadron and he preferred to remain a fighting scout. In the same month, he was made Acting Flight Commander for about 6 weeks, and about April 3, 1917, his rank of Flight Commander was confirmed. The beginning of May he started to introduce a number of new machines for his squadron, these being of an entirely new type. On May 19, he was up with one of the machines in the evening, practising sharp turns and dives, when the wings suddenly crumpled up and he fell 700 ft., being killed instantly. He was buried in a French Cemetry at Monchy Lagache about 8 miles southeast of Perronne, and about 25 miles east of Amiens. Sergeant Herbert Moore Harbach Herbert Moore Harbach was born in Lebanon, Pa., Apr. 4, 1891, graduated from the Lebanon High School in 1911, and entered State College from which he received his degree of Bachelor of Science in Metallurgical Engineering in 1915. He was employed by the Lackawanna Iron Co., at Buffalo, W. Y., and was later transferred to their Lebanon plant to start up the newly erected benzol plant. He was later made foreman of the coke ovens, which position he held after it was bought by the Bethlehem Steel Co., and until he enlisted in the service of his country in September, 1917. He was stationed at Camp Meade, Md., until the spring of 1918, when he was transferred to the C. W.

Jan 1, 1920

By Zhang Zhitie

The limitations in mechanism research of mineral comminution in the past and the basic features of the comminution process have been analyzed. Two kinds of catastrophe model, i.e., cusp model and swallowtail one in the mineral comminution have been put forward. The dissipative structure of the mineral comminution: entropy production rate, extra entropy, extra entropy production and system stability has been discussed. The physical nature of the behavior that an old structure was destroyed and a new one was produced in the mineral comminution process has been brought to light.

Jan 1, 1995

By Paul Swatkowski

A Note About Copyrighted Material ??Permission to Use? has been granted ?Teachthe7habits ?Think win/win (4thHabit) ?Don?t stop here ?i.e., buy the book

Jan 1, 2009

By E. William Rossi, Sean Gallagher, Richard L. Unger

The purpose of this study was to examine the lifting capacity of low-seam coal miners in four restricted work postures (roof heights of 36", 40", 44", and 48"), investigate the associated metabolic costs, and to examine electromyographic (EMG) data from eight trunk muscles during the lifting procedure. Subjects were thirteen underground miners accustomed to handling materials in restricted work postures. Each subject performed two twenty-minute periods of asymnetric lifting in each of four postures during the day of testing. The. frequency of lifting was 10 lifts per minute. A specially designed lifting box incorporated microswitches in one handle of the box and another in the bottom of the box, in order to examine the trunk muscle function at specific points during the lfting cycle. The data collected will be used by the Bureau of Mines to make recommendations for lifting materials in low-seam coal mines.

S., at Niagara Falls, as an expert chemist. There he was engaged in perfect.ing the various kinds of gases, and while thus employed was gassed several times, which so affected his heart and lungs that he was unable to withstand an attack of the influenza which developed into pneumonia, from which he died at the end of 24 hours. He was a member of St. Luke's Episcopal Church, Lebanon, and belonged to the Ancient Accepted Scottish Rite of Freemasonry, Lebanon Lodge 121, I. 0. 0. F. and Camp 65, P. 0. S. of A. Lieutenant Bernhardt Edward Heine Bernhardt Edward Heine, a lieutenant in the Aviation Service of the U. S. Army, died as the result of a fa1I1 in an aeroplane at Fort Sill, Okla., on Aug. 10, 1918. The accident occurred on Aug. 2, when the machine in which he was flying with Lieutenant Carsons fell from a height of 1500 ft.; Lieutenant Carsons was instantly killed, but Lieutenant Heine died from his injuries a week later. Lieutenant Heine was born at Mount Clemens, Mich., in 1895. After attending the local High School he entered the Michigan College of Mines, and became a Junior Member of the Institute while still a student. He graduated in 1916, with the degree of B. S. In 1914 he served as a transitman for the engineering department of the City of Hancock, Mich. Lieutenant Heine had been in the army since 1916, having been with the 'troops at 'the Mexican border. He had been in the Aviation Section since August, 1917.

Jan 1, 1920

By K. Ward

The Environmental Protection Agency (EPA) is beginning to provide compliance assistance visits to various industries, including mining, for Emergency Planning and Community Right-to-Know Act (EPCRA) compliance. The EPA inspectors may consist of a multi-media team deployed to review systems and procedures for EPCRA Sections 302, 304, 311, and 312. The Team’s focus may include emergency response plans, training programs, qualifications of personnel, and release notification protocols. This presentation takes a look at the EPCRA compliance challenges faced by Arizona copper mining and processing facilities.

Jan 1, 2001

By V. Chatain

The environmental assessment of historical mining sites contaminated with various inorganic species, as also the determination of remediation targets require a better knowledge of pollutant-bearing phases. The objective of this paper was to investigate the operational fractionation of arsenic (As) in an As contaminated (ca. 3 wt%) soil collected from a gold mining site in France, where mining activities and smelting processes of gold ores took place until 2004. Single and sequential chemical extraction procedures were performed to evaluate the potential mobility of As according to the fractions to which it was associated in the contaminated soil, and also the part of As sorbed onto soil particles. These procedures used provided information on the nature of As fixation processes in the mining soil studied. Results showed that As appeared mainly sorbed (ca. 72%) with iron on the soil particles, in particular amorphous iron oxyhydroxides. These results confirmed a potential risk of arsenic mobilization under acidic and/or reducing conditions, which frequently occur in mining environment. This research evidenced the importance of the knowledge of As-bearing phases to better predict the mobility of this pollutant and in turn improve the management of As contaminated sites.

Aug 1, 2013