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By A. R. Garcia, A. S. Myerson, W. R. Ernst, J. D. Carruthers, M. D. Franke, L. H. Hilzik

A method for removing nickel and vanadium contaminants from spent HDS catalysts involves pretreating the catalyst with H2S followed by extracting the metals with an acidic solution of ferric ion. The ferric ion solution alone removes significant amounts of active ingredients, cobalt and molybdenum; however, by pretreating with H2S, the extraction becomes more selective for removal of Ni and V.

Jan 1, 1988

By C. Anastasiadis

The wettability of sandstone was investigated using the technique of dielectric spectroscopy in the frequency interval 1kHz-1MHz. The natural wetness of the material was modified to get two different sets of samples, one with sea-water wetness and the other with crude oil wetness. Measurements showed that the electric responses of water-wet and crude oil-wet samples were markedly different beside the fact that the dielectric response of both groups of samples obeys a general fractional power law. The dispersivity, of the complex permittivity component that expresses the material loss with respect to the electric field was found to be the most suitable parameter to check the wettability of the samples.

Jan 1, 2005

By R. G. Swanton

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using pure crystalline apatite to investigate potential causes for low extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4-1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4-1/2H2O morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1991

By P. Somasundaran, J. T. Kunjappu

Spectroscopic techniques are becoming increasingly popular for characterizing the interior of adsorbed layers of surfactants and polymers at solid- liquid interface as well as in the identification of com- pounds on mineral surfaces. This review encompasses the application of fluorescence and ESR spectroscopic techniques to reveal the microscopic environment of the adsorbed layers of surfactants and polymers on minerals with a special reference to the adsorption of anionic surfactants (e.g., sodium dodecyl sulfate) and polyelectrolytes (e.g., polyacrylic acid) at positively charged mineral (e.g., alumina) - water interfaces. Finally, the utility of XPS and auger techniques to identify the surface elemental composition of different mineral species has been related to their flotation efficiency.

Jan 1, 1987

By J de Cuyper, V. M. Lovell, W. Freyberger

The recovery of apatite from the phoscorite ores occurring in the Transvaal, Republic of South Africa, involves a flotation process that is particularly difficult to characterize from a fundamental point of view. However, the reagents used, (tall oil fatty acid, nonylphenyltetraglycol ether, sodium silicate, and sodium hydroxide) can successfully bring about a separation of apatite from dolomitic calcite, which is the most troublesome gangue component. Recently, it has been demonstrated with some flotation feeds that the addition of certain polysaccharides can improve the flotation significantly. It has been shown that the metallurgy obtained is closely linked to the nature of the froth, and this, in turn, is influenced, often dramatically, by the presence or absence of certain of the reagents. The character of the froth depends less on the inherent frothing ability of these reagents than on the presence or absence of fine mineral particles in the froth, and on their surface characteristics and state of aggregation. The polyglycol ether and the polysacchar- ides have been shown to affect these properties, and it is suggested that a major function of these reagents is to modulate the properties of the fine particles in the pulp, thereby changing the character of the froth and giving rise to improved results.

Jan 1, 1976

By A. Goulsbral, D. Harrison, R. Dunne

A programme to reduce cyanide consumption at the New Celebration Gold Mine, situated 32kms South of Kalgoorlie, Western Australia, commenced in the latter part of 1990. Cyanide speciation studies at the time identified that the major loss and consequently consumption was due to the hydrolysis of cyanide, The use of artesian hypersaline waters of high magne­sium content on gold plants in Western Australian Goldfields has meant that economically viable operating pH values during cyanide leaching are around 8.9 to 9.5. The high ionic strength in these waters does to some degree retard the hydrolysis reac­tion. Notwithstanding this, the formation of hydrogen cyanide and its loss due to volatilisation is the cause of the major loss of cyanide on most gold plants in the Kalgoorlie Goldfields. This paper discusses the aspect of oxygen addition during cyanide leaching to decrease cyanide consumption and increase gold recovery.

Jan 1, 1996

By W. R. Ernst

A method for the removal of nickel and vanadium contaminants from spent HDS catalysts involves pretreating the catalyst with H2S followed by the extraction of the metals with an acidic solution of ferric ion. The ferric ion solution alone removes significant amounts of active ingredients cobalt and molybdenum; however, after pretreating the catalyst with H2S, the extraction becomes more selective for the removal of Ni and V.

Jan 1, 1986

By H. Mercado G., J. R. Parga T

Mexico continues to be one of the main producers of silver, lead and zinc; although this leadership is ending because of the use of obsolete technologies, which is reflected in low recoveries of these processes. The country therefore requires to develop on new technologies in the field of nonferrous metallurgy, particularly be'cause it is the second most important source of foreign exchange. A novel method, presented in this paper, demostrates that refractory gold and silver can be extracted from a complex sulphide concentrate by a one stage pressure oxidation in an alkaline cyanide solution, this is achieved by simultaneous liberation_ and solubilization of the precious metals. Both gold and silver extractions are greater than 97%. Factors affecting recovery efficiency, such as: pH, lixiviation time in the reactor, temperature, particle diameter, pressure, % of NaCN and pulp density, were investigated. A summary of actual plant operations is also be included.

Jan 1, 1993

By Eleanora I. Robbins, Motoaki Sato

Many problems associated with acid mine drainage (AMD) are caused by the complex way molecular oxygen (O2) oxidizes reduced matter at surface temperatures. In aqueous solution, O2 kinetically "prefers" to go through the formation of hydrogen peroxide (H2O2) as an intermediate. Being innately unstable, H2O2 is quickly decomposed back to water and oxygen in the presence of dissolved Fe and Mn, both catalysts for the decomposition. Direct addition of H2O2 to AMD produced similar results. Ozone (O3) is a much faster and stronger oxidizer than either O2 or H2O2. In the laboratory, O3 rapidly precipitated Mn, Fe, Ni, Co, Pb, and Ag even in acidic solutions. The experiments indicate that AMD can probably be processed with ozone and metal oxides/hydroxide recovered in flow systems using only septic-tank-size reactors and small sedimentation ponds.

Jan 1, 2000

By Charles Dr. Li, John Dr. Box

Selective flotation and adsorption behavior of zircon and rutile under hot soap conditions have been examined. Conditioning temperature, pH and washing steps were shown to control the flotation selectivity. The adsorption of the sodium soap of oleic acid at zircon- water and rutile-water interfaces was investigated through micro- electrophoresis and adsorption density measurements. The soap adsorption on the zircon surface increased markedly with increasing temperature due to a strong chemisorption/surface reaction, and was almost independent of pH. In contrast, the soap adsorption on rutile decreased at high pH values. A simple physisorption plus hydrophobic interaction appeared to be the principal mechanism for the soap adsorption on rutile at moderate temperatures (below ~70(C), beyond which it may change to chemisorption through an activation process. Water wash, particularly under acidic conditions (pH 2-3), of the rutile particles treated with soap, will lead to a desorption of the soap from the rutile surface by forming an acid salt precipitate.

Jan 1, 1995

By R. N. Tempel, M. Lengke

Arsenic sulfide (orpiment, realgar, amorphous AsS and As2S3) oxidation rates were measured in mixed flow reactors at pH-2 and at temperatures of 25 ° to 30 °C. The measured oxidation rates for arsenic sulfide solids by dissolved oxygen are in the range of 10-11 to 10-10 mole m-2s-1 after being normalized to final surface area. The order of arsenic sulfide oxidation rates decreases at pH-2 from amorphous AsS > realgar > orpiment > amorphous As2S3. Compared to pyrite, arsenic sulfide oxidation rates are approximately 1.5 to 15 times slower than pyrite oxidation rates at pH-2.

Jan 1, 2003

By S. C. Lamey, P. A. Hesbach

This study evaluated the use of regionally produced coal combustion products to neutralize and remove metals from acid mine drainage (AMD). Synthetic AMD mixtures were treated with a number of fly ashes and fluidized bed combustion (FBC) ashes. All of the ashes reduced the volume of the sludge produced and gave a faster settling rate than the sludge produced by treatment with lime. Faster settling allows greater throughput rates. In addition, the FBC ashes, which generally contain alkaline components used for sulfur capture, completely neutralized the acidity and, if desired, raised the pH above 10. The fly ashes, on the other hand, reduced the final volume of sludge but required additional neutralizing agents to attain a pH >5. The pH of the AMD can be taken to above 10 to insure complete removal of manganese, or it can be taken to a more neutral pH of 7 or 8 to allow for the safe introduction of the aqueous phase into ponds or streams. The process combines two industrial waste products to reduce the disposal volume of one of the waste products and to produce an environmentally safe aqueous discharge.

Jan 1, 2002

By Ing. Ludwig Schlebusch

The significant growth of the world population and its demand for an increasing standard of living leaves no other choice than continuously augmenting industrial production and making available steadily greater quantities of raw materials at still better qualities. Therefore, any raw material has to be utilized to the greatest possible extent and processed at optimum economy on large mechanical equipment. The layout of processing facilities of large throughput rates can be based on multiple or single lines. The latter enables the application of large machines of optimum size. Proven equipment for homogenizing, classifying, separating superfine material, sorting and dewatering are-now available in optimum sizes. By the use of these large machines operating cost of pit coal preparation plant can be significantly lowered by reducing the specific requirements regarding space, capital investment, energy, operation and maintenance.

Jan 1, 1980

By B. A. Firth

Australia is the largest exporter of coking and thermal coal to the international market. This market has required that the coal being presented to the customer has a particular level and consistency of quality. In this context, the Australian industry has developed coal preparation practices that allow this criteria to be met while maximising the recovery of coal from the resource. This has required on- going developments in both coarse and fine coal cleaning technology over the past 30 years. Coal flotation has undergone a number of developments with regard to maximising recovery from the overall plant circuit. This includes innovative flotation circuits (split feed), methods of enhancing the use of reagents and control of pH. During the 1990s, there have been major changes in flotation as practised in Australian coal preparation plants. Columns have become the preferred technology for both greenfield developments and plant upgrades. This paper will outline the above developments with a number of plant examples and the reasoning that has driven the change. The ongoing research that is being carried out on new cells to optimise the overall fine coal circuit will also be discussed.

Jan 1, 1999

By Barnaby J. Watten, Sibrell. Philip L., Brian J. Vinci, Andrew E. Friedrich

We evaluated a new process for remediation of acid rock drainage (ARD). The process treats ARD with intermittently fluidized beds of granular limestone maintained within a continuous flow reactor pressurized with CO2. Tests were performed over a thirty day period at the Toby Creek mine drainage treatment plant, Elk County, Pennsylvania in cooperation with the Pennsylvania Department of Environmental Protection. Equipment performance was established at operating pressures of 0,34,82, and 117 kPa using an ARD flow of 227 L/min. The ARD had the following characteristics: pH, 3.1; temperature, 10 OC; dissolved oxygen, 6.4 mg/L; acidity, 260 mg/5; total iron, 21 mg/L; aluminum, 22 mg/L; manganese, 7.5 mg/L; and conductivity, 1400 uS/cm. In all cases tested, processed ARD was net alkaline with mean pH and alkalinities of 6.7 and 59 mg/L at a CO2 pressure of 0 kPa, 6.6 and 158 mg/L at 34 kPa, 7.4 and 240 mg/L at 82 kPa, and 7.4 and 290 mg/L at 117 kPa Processed ARD alkalinities were correlated to the settled bed depth (p<0.001) and CO2 pressure (p<0.001). Iron, aluminum, and manganese removal efficiencies of 96%, 99%, and 5%, respectively, were achieved with filtration following treatment. No indications of metal hydroxide precipitation or armoring of the limestone were observed. The surplus alkalinity established at 82 kPa was successful in treating an equivalent of 1136 L/min (fivefold dilution) of the combined three ARD streams entering the Toby Creek Plant. This side-stream capability provides savings in treatment unit scale as well as flexibility in treatment effect. The capability of the system to handle higher influent acidity was tested by elevating the acidity to 5000 mg/L with sulfuric acid. Net alkaline effluent was produced, indicating applicability of the process to highly acidic ARD.

Jan 1, 2000

By Donald C. Rotherham

The Endako, British Columbia, deposit was initially discovered in 1927 by two local men, Charles H. Foote and Alf Lagdon, who were at that time on a hunting expedition. Four mineral claims were located to cover an area of quartz-molybdenite float that was centered on two small ridges. They subsequently uncovered a 0.5-m (1.6-ft) wide vein on which an inclined shaft was sunk to a depth of 8.3 m (27.2 ft) in 1934. Additionally, a short adit was driven to intersect another vein. Numerous trenches and small pits were also dug. Small test shipments of vein material from this early work were sent to G.S. Eldridge and Co. in Vancouver for metallurgical testing. A concentrate assaying 89.2% MoS, was produced with a recovery reported as 93.3%. The concentrate was essentially free of copper, arsenic, and phosphate. The property was examined by many geologists and engineers during 1934 to 1952, but the only work done was undertaken by the owners in order to maintain their claims in good standing. In 1952, Kennco Explorations (Canada) Ltd. carried out a limited program of bulldozer trenching, sampling, and geological mapping before relin- quishing their option. In 1956, American Standard Mines Ltd. acquired an option on the property, but no assessment work was apparently recorded and the property was allowed to lapse. The key claims were restaked in 1959 by C. Riley and H.T. James of Vancouver. The property was optioned from the new owners by Andrew Robertson in July 1961, and a small amount of trenching was conducted. Robertson, on behalf of his own company, R & P Metals Corp., reoptioned the property in January 1962. The initial results of this work were favorable and justified further exploration. The additional finances required to continue the program resulted in the formation of Endako Mines Ltd. (N.P.L.) on June 21, 1962. Field work by R & P Metals and the first Endako Mines exploration was directed by Bob Couts.

Jan 1, 1991

By David Dvorkin, Thomas C. Anderson

INTRODUCTION A major function of the Mine Safety and Health Administration (MSHA), Denver Safety and Health Technology Center (DSHTC), Ventilation Branch, is to provide engineering analyses of underground mine¬ ventilation systems for coal, metal, and nonmetal in¬spection departments in accordance with field surveys and data analyses. Health and safety problems such as the control of diesel contaminants, dust, methane, radon, and radon daughters all are dependent upon ventilation. It is necessary for the ventilation engineers at DSHTC to have a complete understanding of the various and highly complex ventilation systems used in the nation&apos;s mines. Only through the proper assembly and analysis of data can the engineer determine the causes of prob¬lems and make suitable recommendations. Furthermore, the engineer must have the ability to predict the results of any such recommendations. In the study of the ventilation system at any indi¬vidual mine, it is common practice to collect data on airflow quantities and pressures at key points throughout the mine. However, these data give only a single point¬-in-time view of the system. As the mine develops and progresses, the system undergoes numerous changes; as the mine becomes more extensive, the ventilation re¬quirements increase, and the costs rise. For proper utilization of the available resources, it is necessary for the engineer to have a sound engineering basis for deci¬sions on how best to ventilate the mine. To evaluate the system as a whole, particularly re¬garding possible system changes, it has become necessary to rely on computers to perform the calculations in¬volved in analyzing the network. This chapter sum¬marizes the implementation of such computer capabili¬ties at DSHTC, as well as the services that are available from DSHTC. ANALOG SIMULATIONS AND ANALYSES OF VENTILATION NETWORKS As early as 1954, the US Bureau of Mines (USBM) in Pittsburgh, PA, was using an analog computer as an aid in analyzing ventilation systems. The Mcllroy Fluid Network Analyzer used filament-tube resistance elements and an electrical power supply to simulate mine-ventila¬tion systems electrically. This system is shown in Fig. 1. Analog simulation has proven to be a practical tool, providing fast analyses of complicated problems after the initial setup has been completed. Advancements in electronic technology over the past 24 years have made possible the construction of an analog computer that has streamlined several operating features of the previous machines. The DSHTC Ventilation Branch now has an improved electronic analog computer to assist in the analyses of ventilation systems. General Features As shown in Fig. 2, the analog computer used at the DSHTC Ventilation Branch has three "element" cabi¬ nets, a console, and a printer. The cabinets contain the fan elements and the airway-resistance elements that are used to "program" an analysis problem; each element is independent of the others. The console contains the "patchboard" and the controls necessary to operate the analog computer. The patchboard connects the inde¬pendent elements into the circuit appropriate for simu¬lating the ventilation system. The total system is controlled from a panel on the console, while the value corresponding to each element is set on the individual controls located on the face of each element. The control panel has three visual output displays that give the quantity of flow, the pressure of the output junction with respect to a datum, and the differential pressure across each element. The control panel also allows manual selection of the element to be monitored, or automatic scanning and printing of values for the entire system. Capabilities The analog computer can simulate an existing mine¬-ventilation network. This is accomplished by collecting field data at the mine to give a complete pressure-¬quantity network. Resistance values for each airway branch may be determined from the quantity of flow in the branch and from the pressure differential between the end-point junctions of the branch. The basic rela¬tonship to determine the resistance is expressed as: H=R •Q2 where H is the pressure differential, R is the resistance, and Q is the quantity of air in the flow. After the resistance values are known for all of the airways in the circuit, the elements on the analog com¬puter can be set to the corresponding values. The elements are designed to reflect the basic relationships, with electrical potentials corresponding to pressures and

Jan 1, 1982

By Prakash M. . P. E. Donde

1. INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has often taken a leading role in introducing innovative construction technologies to build its transit system. Most recently, Contract Section E-5a, which included Fort Totten Station and Tunnels was constructed utilizing the New Austrian Tunneling Method (NATM) in soft ground. Along with the station and tunnels, two permanent shafts were also constructed in soft ground employing the NATM technique. This project is located within the District of Columbia on the Greenbelt Route. The subject of this paper is to discuss the unique method of construction of these two shafts, and explore the benefits of applying the NATM technique to the construction of deep shafts. The design of the shafts was performed jointly by Jenny Engineering Corporation of Springfield, New Jersey, and Mayreder Consult of Linz, Austria. The designers also provided construction support services and a resident NATM expert at the site during construction. The construction of the project started in April 1988 by a joint venture of Mergentime Corporation and H. T. Construction, a subsidiary of Hochtief Company from Germany. This $48.7 million construction project has been completed. 2. SUBSURFACE CONDITIONS The two NATM shafts are located primarily in Cretaceous-age deposits that are over 100 million years old. These deposits are intermixed and lenticular in nature

Jan 1, 1993

By R. J. Cornelius

Gold with minor associated copper mineralization in the area of what is now the Bougainville porphyry copper deposit has been known since the 1920s and was probably known in German colonial times, pre- 19 14, although no records persist other than a reference by Stanley (1922) to copper specimens from Kieta that he saw in Rabaul. Stanley did not at the time believe that they came from Kieta. Gold was first discovered at Kupei by Jack Comb in 1929 and the Kieta Goldfield was proclaimed in May 1930. In December 1932, the Tapu Reward Claim at Moroni - the site of the Bougainville Copper concentrator, was pegged by C.W.M. Evans who prospected up river from the West Coast. The Pumkuna (Panguna) Reward Claim on the site of the subsequent porphyry copper deposit was granted in February 1934 to G.A. Myers. n May 193 1, the Kupei Reward Claim was transferred to Bou- gainville Gold Options NL and later reverted to Jack Comb and then the Bougainville Syndicate, as did the Pumkuna and Moroni claims. Most of the interested parties had come from the Edie Creek rush on the New Guinea mainland. In 1935, N.H. Fisher, the geologist in Rabaul for the New Guinea administration who later became director of the Australian Bureau of Mineral Resources in Canberra, reported on the three gold areas. Norm Fisher described the gold and copper mineralization and its habit in great detail and this report had a major influence on the events leading to the discovery in the 1960s. Gold production up to the Japanese invasion probably did not exceed $50,000 in value. Half a ton of copper-gold ore from Kupei was sent to O.T. Lempriere&apos;s in Sydney for assay in the early 1930s.

Jan 1, 1991

Direct force measurements were conducted using an atomic force microscope (AFM) to study the mechanism of copper-activation of sphalerite. The force measurements were conducted between a sphalerite plate and a hydrophobic glass sphere in xanthate solutions of various pHs. The glass sphere may represent the hydrophobic air bubbles interacting with minerals during flotation. The force measurements conducted with unactivated sphalerite in 10&apos;) M KEX solutions did not show the presence of hydrophobic force. On the other hand, the results obtained with copper-activated sphalerite at pH 9.2 and 4.6 showed strong hydrophobic forces. However, the results obtained at pH 6.8 showed no evidence of hydrophobic force, which provides an explanation for the difficulty in floating sphalerite at neutral pH.

Jan 1, 1998