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By T. G. P. Vasquez

The elimination of metal ions from aqueous solutions by biosorption plays an important role in water pollution control. Heavy metals are hazardous to the aquatic ecosystem and pose possible human health risk. Beside the toxic and harmful effects to organisms living in water heavy metals also accumulate throughout the food chain and may affect human beings. Conventional methods for removing metals from aqueous solutions before they are disposed of include chemical precipitation and sludge separation, chemical oxidation or reduction, ion exchange, reverse osmosis, electrochemical treatment, and evaporation. Alternative processing methods are being considered more seriously. Sorption and/or complexation of dissolved metals species based on the chemical activity of biomass, known as biosorption, is the base of the new technology for metal removal and recovery. Different types of biomass (dead and alive) have been investigated for biosorption of heavy metals ions. In the present work, the cadmium biosorption capacity and bioflotation of Rhodococcus opacus were studied. The adsorption capacity of biomass was investigated by batch experiments, the influences of some variables like pH and ion concentration were evaluated and the experimental data obtained for each metal were evaluated and fitted using adsorption and kinetic models. The bioflotation process showed that R. opacus has excellent features as collector and foaming agent after metal biosorption. Around 90% of cadmium uptake by the biomass was achieved by bioflotation.

Jan 1, 2006

By N. J. Grant, D. S. Bloom

P. Coheur and L. Habraken—We read this paper with great interest and are glad to congratulate the authors for their valuable work, supplying an important contribution to the mechanism of tempering on the carbides in vanadium steels. We are in a good position to appreciate this work since we have been studying, for more than a year, Cr-Mo steels of a composition similar, but less highly alloyed (namely 0.1 pct C, 3 pct Cr, 1 pct Mo). Our results are quite in concordance with the authors', however, we wish to point out that it is very interesting to use equally the electron microscope in order to observe the variations of microstructure in steels. We have studied simultaneously the evolution of the carbides in situ with the electron microscope, and, after extraction, again with the electron microscope, and then with X-rays. The first results which we have obtained have been communicated at the Congress of Delft (July 1949) and at the "Journees de la Metallurgie" in Paris (October 1949). These may be summarized as follows: After tempering with varying either the tempering temperatures or the tempering times, the carbides show two evolutions. The first one is connected to the carbides existing in the steels, principally in the boundaries of the grains. For some groups of steels these carbides may coalesce and for other groups they may

Jan 1, 1951

By P. M. Solozhenkin, V. P. Nebera, V. D. Skorohodov

"Aqueous dispersions of air specifically prepared on the basis of flotation reagent solution acquire active properties in relation to the solid surface and may be imply as a medium for flotation ores. Such aerated solutions were defined as Activated Aqueous Dispersions of Air (AADA) with 5-6:1 ratio and the procedure of mineral separation was defined as a flotation process under non-equilibrium conditions. These procedures differ from conventional flotation mainly in reagent interaction with minerals through their adsorption films on gas bubbles simultaneously forming flotation complexes. Gas-liquid mixture is kept till an adsorption layer of reagents close to the limit value is formed on the surface of bubbles. The theoretical basis of AADA is considered.The results of two-phase gas- liquid mixture (AADA) were studied. Two versions of AADA were considered. Electrical surface potential of the air bubbles with the surfactant film, untreated minerals particles in Coulomb attraction and flotation complex formation were analyzed. Special flotation machines were constructed for separation of mineral suspension in air dispersion, whose effectiveness was confirmed in flotation of apatite waste of Kovdor ore. FK-9 machine introduced on Kovdor iron ore combine for the recovery of apatite from current departures of factory. The froth product contained 7.2 % P2O5, with recovery of 44 % apatite, which was processed for getting melted phosphoric-magnesium fertilizers."

Jan 1, 2003

By L. A. Vermeulen, D. D. Howat

New distribution functions are derived to describe the size distribution of grinding elements in ball mils. The formulations are based on the assumption that abrasive as well as impactive interactions occur during bal milling-an assumption that is supported by a large body of experimental evidence. It is shown that the functions can be used in the estimation of the magnitudes of abrasive and impactive components in the total rate of bal wear. The relative magnitudes of the wear components provide a basis for optimization of the chemical and metallurgical properties of the balls in a given milling situation. However, it is contended that these quantities are also useful indicators of the relative intensities of the abrasive and impactive interactions that are operative in the size reduction of mineral particles within ball mils. These quantities can be determined for any industrial ball mil, and their magnitudes provide practical guidelines for mil operation. The theory is used in an analysis of samples of ball charges from two industrial ball mils, and it is also applied to al the data on bal-size distributions found in the literature. The qualitative correlation between the calculated values of the wear components and the reported operating conditions is good for a variety of industrial ball mils, in conformity with the hypothesis that the relative magnitudes of the wear components are related to the milling conditions.

Jan 1, 1986

By K. D. Peaslee, J. M. Soto, IéDé Smith, A. D. Saikia

Spinel-forming refractories reduce penetration of metal and slags through a tightening of the lining resulting from the volume expansion associated with spinel formation. Sintered spinel is often added to reduce the overall volume increase that results. Tests were carried out to evaluate the difference between performance in spinel¬forming and spinel-containing refractory mixes. Eight refractory linings, one (1) pure magnesia, three (3) magnesia-base spinel-forming and four (4) alumina-base spinel- containing dry vibratable mixes, were tested for four hours in contact with a low-carbon, low-manganese steel in a coreless induction furnace at temperatures in excess of 1600°C. Afterwards, sample were cut, and wear and penetration were measured. For magnesia-based mixes wear was minimized using 20-30wt. spinel formation although further experiments are required to determine the optimal value. For alumina-based mixes, there seemed to be an optimal ratio of spinel added to spinel formed that minimized penetration and wear at the slag line. Sidewall accretion occurred and the accretion was the highest for the mix with the ratio of spinel formed to spinel added near the optimum value. Therefore to design an optimum refractory mix the benefits of higher ratios of spinel added to reduce penetration and wear at the slag line will need to be balanced with the tendency to form accretions on the sidewalls of the furnace.

Jan 1, 2004

By S. Naidu, J. Kelley, Roger Amato

The Alaskan Continental Shelf covers 76 % of the total shelf area of the United States. There are a lot of potential gravel deposits in the Alaskan offshore region. The gravel resources are currently not feasible for mining for the following reasons (U.S Congress, 1987): 1. Much of the glacial gravel is poorly sorted. 2. Gravel deposits are overlain by sandy and muddy layers. With the sea level expected to rise 70 cm in the next 100 years (Intergovernmental Panel on Climate Change, IPCC, 2001; Day, 2004), erosion of coastlines will be a major problem not only in Alaska but worldwide. Hence beach nourishment projects designed to minimize erosion will require large volumes of sand and gravel. Offshore areas will become a logical source for the fill material because of their proximity and ready availability. It is likely that future supply of coarse aggregate in Alaska may involve exploitation of marine deposits. The Chukchi Sea is a potentially favorable region for this type of mining because of extensive deposits of paleo beach and other relict gravel found in the near shore region (Stauffer, 1987). However a systematic analysis of potential gravel resource has not yet been conducted and it is the purpose of this research to estimate the size, extent and variability of gravel material that may be available in the continental shelf, offshore Kivalina.

THE following employment items are made available to AIME members on a nonprofit basis by the Engineering Societies Personnel Service, Inc., operating in cooperation with the Four Founder Societies. Local offices of the Personnel Service are at 8 W. 40th St., New York 18; 100 Farnsworth Ave., Detroit; 57 Post St., San Francisco; 84 E. Randolph St., Chicago 1. Applicants should address all mail to the proper key numbers in care of the New York office and include 6c in stamps for forwarding and returning application. The applicant agrees, if placed in a position by means of the Service, to pay the placement fee listed by the Service. AIME members may secure a weekly bulletin of positions available for $3.50 a quarter, $12 a year. MEN AVAILABLE Project Manager or Construction Engineer, 48, married. Twenty-five years' experience on mine, mill and smelter construction work, design and operation, U. S. and Mexico. Speak Spanish. Now employed; available 30 days notice. Prefer U. S. or Mexico. M-698-489-E-1-San Francisco. Mining Geologist, 53, single. Eleven years' intensive field experience giving a completely practical competence for the smallest or largest of areas; plus the highest possible grade of academic background and independent research qualifying for top rating. Available in thirty days or less. Any location acceptable. M-699-3611-E-7-San Francisco.

Jan 1, 1952

By R. G. Davies

THE effect of ordered structures upon steady state creep has not been extensively studied although it has been demonstrated that the brass,' ie,' and Fe3Al3 superlattices increase the creep resistance. Suzuki and Yamamoto observed an acceleration in the creep rate of Ni3Fe below the critical temperature for order, (T, - 505"), for both the ordered and disordered states, and that the activation energy for creep was independent of the applied stress. They concluded that a dislocation climb creep mechanism was operative down to 300°C which is - 1/3 TM where TM is the absolute melting temperature. This is quite remarkable in that it is usually observed that climb controlled creep in both pure metals and alloys ceases below - 1/2 TM (590" for ie). With this anomaly in mind it was decided to reinvestigate creep in a 75 at. pct Ni-25 at. pct Fe alloy. The creep apparatus and operating conditions have already been decribed. Since Ni-Fe alloys order very slowly, it is possible to have a disordered alloy at a temperature below T,. A long anneal at a temperature just below T, produces considerable long-range order;5 the ordering treatment in the present investigation was 150 hr at 485°C which gives an antiphase domain size of-SOW

Jan 1, 1963

By Bruce Congleton

The Florida phosphate industry is a leader in environmental control, both in terms of dollars spent and significant achievements. For instance, since 1960 the phosphate industry has spent over $71 million for air pollution and control devices, including installation, research and development and maintenance. Water pollution control expenditures also total in the millions, with over $69 million spent in the same 10 year period. The industry also is a leader in water conservation measures, having spent nearly $ 18 million since 1966 for conservation devices. Since phosphate is mined by strip mining, land reclamation plays an important part in the environmental control picture. Here again, the phosphate industry has met the challenge with a voluntary program of reclamation which accounts for over 20,000 acres of land useable after mining has taken place. In terms of progress in environmental control, the industry has been able over the years to solve within the limits of technology the fluoride emission problems it once had, and is currently at work solving sulfur dioxide and particulate problems. In just the past year the industry also has been extremely successful in limiting phosphorus and nitrogen discharges into area streams. The industry continues to cooperate with state and local pollution control officials on matters of environmental control, and future plans include even closer cooperation and assistance, as well as increased expenditures.

Jan 1, 1972

By J. F. T. Agapito

Significant economic benefits can result when rock mechanics is applied within a practical framework and integrated within the other engineering functions of the mine organization. Such application and integration requires management support and understanding of rock mechanics as a practical tool to help attain high standards of safety, productivity and resource recovery. For such an approach, a long-term geotechnical program is needed in most operations to build an adequate data base and to ensure that design and ground control issues are handled in a cost-effective manner. Best usage of rock mechanics in mining occurs when management recognizes the application as a long-term investment, where time is needed to realize good returns. The need for this approach is due to the difficulty in accurately predicting ground conditions ahead of mining. The practical application of rock mechanics must follow an iterative process of design and verification based on site-specific experience to account for geologic and mining impacts. Ground conditions experienced during mining must be used to check the initial mine design and, if necessary, to provide a basis for design modification. Such a practical rock mechanics program includes comparative experience, in situ instrumentation and numerical modeling. The program begins with the geologic site investigation and continues throughout the life of the mine. It is an integral part of mine planning and operation.

Jan 1, 1991

A joint statistical report released by the U.S. Department of Commerce and U.S. Securities and Exchange Commission indicates that business investment in new plants and equipment is expected to total $81.8 billion during 1971. This figure is based on the findings of a survey conducted in late April and May and reflects about a 1 ½ % decrease in investments from the $83.1 billion projected in February. Mining, on the other hand, is still in a bullish mood and is expected to spend $1.99 billion in 1971 compared to $1.89 billion in 1970 and $1.86 billion in 1969. Based on figures quoted above, mining investment in 1971 should show a 5.2% increase over 1970. Carl E. Bagge, president of the National Coal Association, was the dedicatory speaker at the new Milton R. Young Station of the Minnkota Power Cooperative in North Dakota. This new power plant incorporates many innovations which have overcome the problems of using the low-cost lignite abundant in the area. According to Bagge, this development and President Nixon's recent request for an extra $10 million for coal gasification plants is helping the region lead the way in providing for the power needs of the future. He also maintains that gasification of coal can reconcile coal consumption with the demand for cleaner air, and also assure the nation of adequate pipeline gas.

Jan 1, 1971

ALEXANDER BRYDEN Alexander Bryden, clean of engineers in the anthracite mining field, and a member of the pioneer Pittston family, was claimed by death Wednesday, September 26, 1917. The announcement was not a surprise, as he had been in a critical condition for several days. Mr. Bryden had been in failing health for a year past, but his indomitable will kept him at his accustomed duties until quite recently. Two weeks before his death he attended the regular weekly meeting of the Board of Directors of the Miners' Savings Bank in Pittston, Pa. At that time he apparently felt that his end was fast approaching, as he bade farewell to his associates on the bank board. Until a few days before the end, he continued to give attention to business matters at his home, in preparation for the end, which he met unflinchingly. In the passing of Mr. Bryden, northeastern Pennsylvania loses one of the best-known mining engineers, and the community, a man who, throughout his long life, was actively interested in its social welfare and business prosperity. He was for many years prominent in the management of the mining operations of the Pennsylvania Coal Co., and at the time of his death held the position of consulting engineer of the Pennsylvania and Hillside Coal. Companies.

Jan 12, 1917

By M. D. G. Salamon

If a transition from one equilibrium state to another occurs during the course of mining, energy transfer takes place in the rock mass, which is assumed to be an elastic continuum. The energy components are defined as follows: the work done by external and body forces, W; the increase in stored energy in the mass, Uc; the strain energy in the rock mined during the transition, Urn; the work done on mine support or backfill, Ws; and the released energy, Wr. The energy balance is defined as (W + Urn) - (Uc + Ws) = Wr> 0, where the first set of components in parentheses represents the sources of energy, while that of the second corresponds to the known modes of energy expenditure and the component on the right is the unaccounted-for energy surplus, which must be released and dissipated in some form. The inequality Wr ~ Urn> 0 applies. Expressions for the energy components are derived first for the general case and then for the 'slit' modal used to simulate tabular excavations. Through specific examples, the importance of the progressive nature of mining is emphasized. The size of the steps used to enlarge the excavations appears to play a significant role in the mode of energy transfer. This observation forms the basis of the second paper in this series of two papers.

Jan 1, 1984

In contrast with mining in areas close to the main centres, mining in remote areas is characterised by comparatively high initial investment and relatively high running cost for the life of the mine. This is because of:the real cost of establishing and running the operation at a location distant from the necessary infrastructure; and the perceived risks priced into their costs by the multitude of suppliers involved in the project. Optimal co-operation between the mine and the supplier in developing the right rela tionship and the correct technical solution permit both cost elements to be reduced. This re duction may well mean the difference between success and failure. This paper examines the possibilities for optimising the contribution of the equipment supplier to the overall success of the process. Issues covered include the necessity to provide more than merely equipment fit for the purpose , but also the need to maximise the benefits of equipment ownership over the life of the mine. A simple method of determining the optimum timing for equipment replacement or rebuilding is proposed . Furthermore the maintenance contract (or performance agreement) is suggested as a means of leveraging the supplierÆs commitment to the mining operation. The specific examples are based on experience with mobile equipment but the methodology has relevance to other equipment and supplies.

Jan 1, 1998

[ ] (14) SCREENS: Description of Allis-Chalmers' complete line of vibrating screens for the mining industry is contained in a new 8-page bulletin. Primary scalping, secondary scalping, and conventional screens for wet or dry sizing and screens for heavy media separation are included. Also given is a typical fiowsheet showing how horizontally operated Low-Head screens are used in the sink and float process. (15) MILLS: Forty-six years of experience and 4000 installations throughout the world lie behind the seven basic types of mills illustrated in a recent bulletin from the Hardinge Co. Fields of application and materials handled in various installations are listed. (16) BLOWERS & COMPRESSORS: A brochure describing the manufacturing facilities and the axial and centrifugal blowers and compressors made by the Sawyer Bailey Corp. is now available. (17) LINATEX: The first catalog of the Linatex Corp. of America has been issued, outlining the advantages claimed for this special form of natural rubber, when used in corrosion, abrasion, and vibration resisting applications. (18) WIRE ROPE: Twenty-four pages packed with concentrated wire rope data is the way E. H. Edwards Co. describes a booklet which they are now making available. It was condensed from the Edwards general catalog to provide users with a concise guide to every important phase of wire rope production, maintenance, and use.

Jan 1, 1952

The subject of government involvement in industry is, to say the least, a touchy one. For many it conjures up thoughts of socialisation or nationalisation. For others it is a desirable objective and is seen as a means of social reform by giving government a greater say in the control and distribution of human, financial and natural resources for the betterment of the community. Whatever your point of view, it is difficult to deny that government involvement exists to lesser or greater degrees in all industries. The mining industry is no exception and the degree of government involvement is probably greater than it is in other industries. I think it is important to remember when talking about government involvement in industry to recognise that there are different types of involvement and that all governments have a right, if they so desire, to become involved in whatever way they choose. The decision of a government to increase its direct or indirect involvement must, of course, be taken in the national interest. Governments, if we are still old fashioned enough to believe in ministerial and electoral responsibility, must make up their own minds about whether their actions are in the national interest and they must be prepared to accept the consequences of that action, good or bad. For instance, they must decide

Jan 1, 1975

Dartbrook (Hunter Valley and South Bulli (Southern Coalfield) Collieries provide contrasting settings for gas sorption studies. Gas compositions at Dartbrook are dominated by carbon dioxide, with minor methane, while those at South Bulli are dominated by methane with minor carbon dioxide. Total gas contents at Dartbrook are also significantly greater than those at South Bulli. The two collieries are also contrasted in terms of coal composition and mining environment. Dartbrook Colliery mines a relatively small sectionb(4m) of very thick seam (up to mapproximately25m); the coal is vitrinite-rich, high volatile bituminous. South Bulli mines most of the seam thickness, with coal being an intertinite-rich, medium volatile bituminous coal.Coal samples have been collected from in-seam gas drainage holes for evaluation of relative gas desorption rate (methane versus carbon dioxide). Following adsorption isotherms, petrography, chemistry (proximate and ultimate analysis) and pore structure analysis (carbon dioxide surface area, mercury porosimetry). Bomb desorption studies indicate different behaviours for methane desorption at these two collieries desorbed gas compositions at South Bulli show a small enrichment in methane content. The opposite is observed at Dartbrook. Both collieries show enrichment in CO2 in the residual content. Adsorption studies show marked variation in adsorbed gas contents for methane and carbon dioxide at each colliery and between collieries. These variations are related to differences in coal pore structure, chemistry and Petrology.

Jan 1, 1998

By Arthur A. Center

World production of electrolytic zinc has shown an increase for each year since 1932. Production up to 1936 was summarized in my earlier paper [Trans. A.I.M.E. (1936) 121, 453-4641, and this present paper carries the subject through 1943. During this time of increase, it is safe to say that the average purity has been raised more or less continuously, and the amount of four-nines metal has been in- creased. While the period reflects preparations for and the carrying on of the present war, electrolytic zinc proved its value in many industries as a peacetime metal in the years from 1919 to 1940. World production (Table I) increased from about 594,000 tons in 1936 to around 858,000 tons in 1943; United States production increased from 127,171 tons to 329,903 tons for the same years. Total production of primary zinc in the United States is given in the first column of Table I; retort production of primary zinc, obtained by difference, in the last column. The curves drawn from these figures are shown in Fig. I. They represent continuations of the curves in the earlier paper that cover commercial production of electrolytic zinc from its inception in 1915 to 1935. The earlier paper gave data for total world production and foreign retort production (calculated therefrom) and showed curves of electrolytic vs. retort production

Jan 1, 1944

By L. K. Jetter, C. J. McHargue

DEVELOPMENT of preferred orientation in uranium is of interest because of the strongly anisotropic properties of the orthorhombic crystal structure. Harris&apos; reported inverse pole figures for rolled uranium rods which showed <010> and <410>* to be parallel to the rolling direction after On 0.19-in. spherical X-ray diffraction specimens taken from the center of the middle section of each rod, pole distribution data were obtained by the spectrometric method described previously.4 The specimen was rotated rapidly about the axis coinciding with the rod axis in order that a large number of grains could be scanned and was rotated slowly about an axis perpendicular to the rod axis. The variation in the diffracted X-ray intensity was recorded as a function of the latter motion (angle 4). Fiber-axis distribution charts (inverse pole figures) were prepared by the method described by Setter, McHargue, and Williams." After having been corrected for background radiation, the pole distribution data (I vs ?) were normalized. A normalizing factor for each plane has been shown to be Iranaom = f I sin 4 ? 4 and was obtained by graphical integration from the data for that plane plotted as I sin ? vs ?. The axis-distribution charts deduced from the normalized pole densities are shown in Figs. 1 to 3. On these charts, the contours indicate angular positions of equal normalized axis density,

Jan 1, 1958

By T. A. Silva, A. C. Bragança

Lime has been added to the iron ore slurry transported by the Samarco pipeline since its operation start-up in 1977.Initially, internal corrosion was the main concern therefore the reagent was used only for pH correction. Over the last ten years, though, transport of more complex slurries demanded a significantly higher dosage of lime to guarantee adequate rheology control. Several other reagents have been tested for the same purpose yet none has proven to be as effective regarding technical performance, environmental impact and cost. However, an alternative was sought so that the slurry rheology could still be controlled in case lime addition became impracticable. The objective of this paper is to present a technical solution for this matter, which takes into account environmental aspects. It consists of adding soda for pH correction and an organic coagulant as a rheology modifier. The latter is a quaternary ammonium salt which affected the slurry transport properties in the same manner as lime when tested in a laboratory. It showed no plug formation and allowed solid particles to settle, forming a loose sediment after rest. These results indicate a low probability of plug occurrence in the pipeline and the formation of a readily reslurryable sediment upon shutdown of the pumping system. Industrial tests should be performed in order to validate the laboratory results.

Jan 1, 2007