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By Ruiren Jin

In alkaline pulp, galena is depressed by sodium carboxymethyl cellulose (NaCMC), while Cu(II)-activated sphalerite exhibits a high flotability so that satisfied separation can be achieved. In addition to hydrogen bonding, chemical bonding of NaCMC with galena is confirmed by IR; only hydrogen bonding is involved between NaCMC and Cu(II)-activated sphalerite. It is also found that the greater the degree of substitute and polymerization of NaCMC, the stronger the depressive effect of NaCMC and that lower stirring speed favors the depression.

Jan 1, 1987

By C. A. Fleming, R. G. Williamson

Process development for Eskay Creek began in early 1990 at Lakefield Research, and was initially focused on producing a high-grade/high-recovery concentrate for sale. Owing to the significant base metal sulphide (Cu, Zn, Pb) content of the ore, such a product would have made an attractive feed to a copper smelter, while a gravity and/or flotation flowsheet would have circumvented many of the environmental permitting problems that were anticipated. In the event, it was found that neither gravity nor flotation (nor even a combination of the two) was able to produce a discardable tailing and, in late 1990, attention shifted to the development of a hydrometallurgical flowsheet.

Jan 1, 1995

This paper presents the latest developments in the flotation model being developed collaboratively between the Julius Kruttschnitt Mineral Research Centre in Brisbane, Australia, and the Mineral Processing Research Unit of the University of Cape Town in South Africa as part of the Australian Minerals Industries Research Association (AMIRA) P9 Project. It includes: - characterisation of flotation cells using the bubble surface area flux, Sb; - relationship of Sb to the overall flotation rate constant; - determination of the froth recovery factor; - evaluation of ore floatability; - modelling of entrainment - development of the Floatability Characterisation Test Rig (FCTR); - use of the model in design and optimization of flotation plants; and - current and future work.

Jan 1, 1999

By D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By J. C. Squire, E. W. Baker, G. A. Sullivan, G. W. Flathers

A mine collapse severs communication with trapped miners. Landlines are crushed and commercially available radios cannot penetrate hundreds of feet of dense, conductive earth without the use of regenerative repeaters that may also be crushed. This paper describes a proof-of-concept device that uses seismic P-waves, instead of radio waves, to allow communication of a code that represents prearranged messages, including the safe haven location identifier, number of people and air quality, from trapped miners to aboveground rescue units. The transmitter designed is about 0.03 m3 (1 ft3) in size and can broadcast for four hours from its 27-kg (60-lb) battery pack. The receiver consists of a geophone and a 2.5-kg (5.5- lb) signal conditioning unit attached to a laptop computer, which displays the communication signal in real time. Testing in a bituminous coal mine with an MSHA representative revealed the device was able to transmit through 271 m (890 ft) of overburden, at 0° and 12° from vertical, using 500 W of power.

Jan 1, 2009

By W. C. Baver

Even before the energy crisis developed in the early '70's, considerable research world-wide was being directed towards the development of schemes to both reduce the energy requirements and to reduce air pollution emissions associated with the manufacture of glass. In many cases the sought-for solutions would benefit both objectives. If, for example, the glass batch could be consolidated into such compact forms as briquettes or pellets, they could be preheated in a moving-bed heat exchanger with the high-temperature exhaust gases from the glass furnace. Lower furnace temperatures would thus be possible with a corresponding reduction in heat losses and total fuel consumption. Moreover, the lower temperatures would also reduce the amount of nitrogen oxides generated in the furnace and emitted to the atmosphere. Many tests on consolidated glass batch have been run in many countries. In some cases, extended tests on production furnaces have also been included in the programs. For various reasons, however, none of these has proved to be economically attractive. The current, but temporary lull in the rapidly rising cost of energy which has been with us in recent years, has reduced the push for research for energy saving means for melting glass. A few of the current programs will be discussed. Since raw material requirements, primarily physical in nature, are affected by some of these schemes, these will also be considered.

Jan 1, 1986

By Joyce A. Ober

Minerals for electronic and optical uses divide easily into two sections: 1) quartz and 2) minerals other than quartz. QUARTZ The properties of quartz crystal that make it useful for radio communications were discovered in 1918. Since that time, an in¬dustry for the mining and processing of natural quartz crystal has grown, matured, and been almost entirely replaced by new tech¬nology. The new technology still involves quartz crystal, but ma¬terial that is grown rather than mined. An economic summary of the commercial growing of quartz crystals has a place in a handbook directed to the mineral engi¬neering industry because quartz crystals have long been an impor¬tant commercial mineral, and the raw material for cultured quartz - ¬that is to say, quartz crystals grown through the ingenuity of man - is still natural quartz. Nearly all the natural crystals that have been used for elec¬tronics and optics came from Brazil. The larger pieces which met rigorous standards of quality were used for electronic and, to a lesser extent, optical components. Smaller pieces and fragments were used for vitreous silica. The need for high quality material in quantity led to US government sponsored research and exploration programs in the 1940s. No deposits meeting the very rigid requirements for electronic-grade quartz were found, but other projects resulted in the development of a process for the factory growth of beautiful crystals of prescribed shape, size, and quality. Domestic deposits of appropriate quality were identified to use as raw materials for the quartz culturing process. The development of the cultured quartz crystal illustrates the success that technology can have in adapting a product of the mine to increasingly sophisticated uses. A remarkable achievement per¬haps, but foreshadowed by experiments by Giorgio Spezia (1908), an Italian geologist studying the relative effects of temperature and alkaline environment on the solubility of quartz. Modem radio equipment is most often controlled as to fre¬quency by the presence in the circuit of a separately added crystal¬ - the 1918 discovery responsible for the existence and growth of the quartz industry. The crystal is quartz, but this component is a carefully oriented and prepared slice from a crystal, but not a crystal as recognized by a rock hound or seen in a museum. How quartz operates to control frequencies is not a proper subject for a handbook on industrial minerals, and references should be consulted (Cady, 1964, Mason, 1964). Quartz belongs to a class of materials called dielectrics: those that do not conduct an electric current but permit electric fields to exist and act across them. Quartz shows the piezoelectric effect, which means that when a quartz plate is mechanically deformed against its natural stiffness, one of its surfaces becomes negatively charged, the other positively charged. When the plate is released quickly from the stress, the charges disappear as the plate regains its original shape, but because of mechanical momentum the plate deforms in the opposite direction (to a lesser amount) and the surfaces correspondingly become charged in the opposite direction. By thinly coating the two surfaces with metal and attaching flexible wires, these charges can be brought into an electronic circuit. If the surfaces are suddenly electrically charged by movement of current through the wires, the converse piezoelectric effect occurs and the plate deforms. Carry the thought further and it is realized that an alternating current flowing through the wires responds to the mechanical oscillation. By controlling the thickness of the plate, its mechanical vibration frequency can be varied through a wide range. One type of quartz plate, the AT-cut, has a precisely defined orientation with respect to the crystallographic axes of the crystal and vibrates on a microscopic scale much as a book would deform when placed flat on a table and the top cover moved parallel back and forth with the hand. At least 17 other orientations have been studied, some of which have preferred uses in various applications (Cady, 1964). The quartz crystal industry is composed of three main segments (excluding fused quartz and quartz used for optical purposes): 1. Natural electronic-grade quartz crystals. Mined quartz suitable for fabrication into piezoelectric units. Zlobik (1981a) esti¬mated the waste to ore ratio at 1:1000 to 1000 000, depending upon the deposit. 2. Lasca. Mined quartz usable as feedstock in the production of cultured quartz. Approximately 0.63 kg of lasca are required to produce 0.45 kg of cultured quartz. 3. Cultured quartz. Cultured quartz is produced from lasca feed¬stock in a process of crystal growth in an autoclave under conditions of heat, pressure, and time. It is estimated that 0.45 kg of cultured quartz is equivalent to 1.4 to 4.5 kg of natural quartz crystal in yield of commercial quartz suitable for slicing into piezoelectric units. The chronology of the development of the quartz crystal industry both natural and cultured follows: Date Comment 1918 Discovery of the piezoelectric effects of quartz crystal 1921 Application of the piezoelectric effects of quartz crystal in the circuitry of radios 1948 Establishment of a quartz crystal commodity stockpile by the US Government 1952 US consumption of natural quartz crystal at an all time high of 228 t 1958 First commercial production of cultured quartz crystal 1970 Cultured quartz crystal production exceeds imports of nat¬ural quartz crystal 1971 Cultured quartz crystal consumption surpasses natural quartz crystal consumption

Jan 1, 1994

By George A. Lawrence

A new super-large 100 m3 (3500 A3) pneumatic mechanical flotation cell is now available to meet future mineral processing challenges. Several innovative design concepts represent a marked departure from conventional flotation cell designs. The radial discharge from the pump action rotor and the overhung vane type stator is contained in a conical bottom cylindrical tank with no dead comers. Peripheral launders collect froth overflowing the entire circumference of the tank and these launders are of a hexagonal design permitting cells to be nested together in a honeycomb fashion. This new flotation cell is powered by a custom designed hydraulic motor package that provides infinite speed control in individual cells and a soft start under load

Jan 1, 1993

By A. R. MacPherson

The procedure to arrive at an energy efficient autogenous grinding plant is carried out in the following steps: First Step - Determine power requirements to grind a particular ore. This work carried out on small samples ground in a 450 mm diameter Aerofall Hill and the results are checked against a standard Bond Index test. Second Step - A bulk sample from the ore zone is ground in a 1.8 m diameter pilot mill. This work is carried on until the power objectives as indicated from the first step have been realized. Third Step - Correlate the pilot mill data, with the data from the numerous samples ground in the small 450 mm mill and arrive at design criteria for the commercial plant. Ensure commercial mill design will be suitable to obtain similar results as those obtained in the pilot mill.

Jan 1, 1981

By Isiah M. Warner, Philip Oldham, John Kennedy, Bennett D. Lass

A new method for determination of residual flotation oils on beneficiated kaolin clays has been developed The method, which yields qualitative information, is based on fluorescence measurements employing a spatially resolved, polychromatic illumination source for excitation, and a two-dimensional detection scheme using a silicon-intensified, video imaging device The method was used to identify residual oils on a beneficiated, Washington County, Georgia, crude clay The results were compared to a similar qualitative analysis performed via capillary column gas chromatography using a flame ionization detector The video fluorometry was the preferred method of analysis

Jan 1, 1983

By Kim McKnight

Dupont has successfully incorporated a Floatex Density Separator into its wet-gravity operations for the recovery of zircon from titanium tailings. Results indicate that the Floatex achieved a zircon recovery of approximately 95% while rejecting similar amounts of quartz and other gangue minerals. Additionally, a unit capacity approaching 16 tonnes/hr/m2 was achieved. Results also show that the alumino-silicates can be separated into other product streams that will further improve process economics and minimize waste material. The improved plant feed grade provided by the Floatex has allowed for either an increase in overall plant capacity and/or final product grade. This paper will present the findings from the in-plant study.

Jan 1, 1996

By P. Sarnoff

Gold has always been a crisis investment. For centuries gold has been considered globally the money of last resort. In time of war, inflation, financial uncertainty, political upheaval there has with few exceptions always been a flight to gold. The gold paradox simply is that even though we have gone through for the past handful of years all the kinds of. anxieties that would cause the gold price to rise, it has instead dropped drastically. Figure 1. illustrates the important factors that influenced the gold price significantly up or down before 1987. Obviously, since then, even though we have had wars, inflation, financial problems involving breaking banks and thrifts let alone collapsing financial institutions, the gold price has both in the long-term and the short-term trended downwards. Figure 2. depicts the gold price path since 1987. If the presence of time-honored and time-tested factors that should have driven the gold price up didn't do the job, then logic dictates that new factors to drive the gold price down and keep it depressed arose. And they did. But before addressing these depressants permit me to turn to the arcane art of gold price prediction and fore-casting.

Jan 1, 1992

By A. Shtiza

This literature review discusses the role of the Albanian institutions, the natural resources industry, potential investors and stakeholders in order to provide a set of indicators that can help to monitor amelioration within sustainable development principles. A map with the potential prospects of the natural resources will be a first step in identifying the further potential for exploitation. Mineral resource policies and governance, sustainable processing and supply chain as well as environmental management information system are some of the crucial tools identified, that will help to set up the indicators and quantify the achievements in environmental management in Albania. Moreover, the integration of practices that will support institutional capacity building; follow-up practices; the mainstreaming of global environment into planning; and the compliance monitoring process will additionally improve the environmental situation in Albania. Aligning business strategy with environmental policy, socio-economic analysis, environmental auditing are decisive tools in order to provide the Albanian authorities with a clear overview of the economic costs and the social benefits for sustainable development.

Jan 1, 2011

By K. Bunney

A high-pressure laboratory elution rig was commissioned to simulate industrial Zadra and AARL elution conditions for the stripping of gold, silver and mercury from loaded activated carbon. It was found that cyanide was essential for the efficient elution of both mercury and silver, while gold was found to elute most effectively in hot, low-ionic strength solutions. Therefore, the standard AARL-type elution, which implements a cyanide soak and water elution, results in a lower recovery of mercury and silver from the carbon. No single set of conditions was found whereby gold, silver and mercury can all be effectively eluted in a single step. However, sequential elution conditions can efficiently recover all metals and provide a potential approach for separating these metals.

Jan 1, 2010

By D. Dunbar

The flooding of open pits is now receiving considerable attention from the mining industry as an option that may minimize environmental impacts, particularly when anoxia in pit-lake deep waters can effectively eliminate oxidation of pit-wall sulfides. This paper describes a state-of-the-art, coupled physical-geochemical pit-lake model. The model is used to verify that a controlled, two-stage infilling of the open pit at the Kori Kollo gold mine, southeast of La Paz, Bolivia, would result in a cost-effective, environmentally responsible closure strategy. By filling the pit initially with highly saline surface waters and naturally saline deep groundwater and then capping with fresh river water, a very stable and strongly stratified pit lake will be developed. In addition, the stratification will result in the isolation of metal-rich saline bottom waters from surface waters of good quality. Results of this model provide defensible predictions of the physical stability and evolution of water quality in the Kori Kollo pit lake over time. The model results indicate that anoxic conditions will develop below the fresh-saline water boundary within one to two years, followed by the rapid onset of sulfate-reducing conditions in the bottom waters. Hydrogen sulfide produced by sulfate reduction will readily react with dissolved metals to form highly insoluble metal sulfides. The process results in the gradual removal of metals from the water column and the concomitant improvement of water quality over time. A notable benefit of this strategy is that it can be fully integrated with other mine site closure options as well as future environmental-management strategies. The proposed plan allows for the safe isolation of saline waters, the potential for passive treatment in anoxic bottom waters of ARD seepage from other mine site operations, should they arise, and a repository for future reactive wastes that could be effectively isolated in a physically and chemically stable environment.

Jan 1, 2003

By Robert S. Lehto

Zinc concentrates received in La Oroya zinc refinery are marmatitic in nature, contain about 11% iron and traces of other metal values, Figure 1 shows the zinc circuit. The calcine from the roasted concentrates is leached in spent zinc electrolyte. Major part of the impurities is iron which has been oxidized to its trivalent form, This is the origin of the zinc leach residue for which the ZILERET process was developed and so named. The impure liquor from the leach is sent for purification and thence to electrolysis- zinc deposits on aluminum cathodes from which: it is stripped, melted and cast into slabs Typical assays of zinc calcine and leach residue are given in Table 1. Metal values contained in the leach residue, without counting any value of iron, amount to roughly $130 per short ton.

Jan 1, 1969

By Yuusaku Tominaga, Sukumar Bandopadhyay

A power-series trend curve of elapsed time was estimated by using time series data of measured concentrations of carbon monoxide in the Taiheiyo coal mine, Hokkaido, Japan. The difference between the moving average concentration data and the estimated data from the trend curve showed linear correlation when plotted on a normal probability paper and a correlation coefficient value of 0.99. It is concluded that the estimate of carbon monoxide concentration using moving average values of concentrations compares very well with the results obtained from the trend curve within the three-sigma (standard deviation) range of the distribution. Thus, it is believed the results can be used to monitor and detect abnormal ventilation conditions in a ventilation network such as the occurrence of spontaneous combustion at an early stage.

Jan 1, 2002

By A. E. Foscolos

British Petroleum (BP, 2005), indicates that world reserves for oil to be 1198 billion barrels, for natural gas the equivalent of 1156 billion barrels of oil and for coal the equivalent of 3219 billion barrels of oil. If we take into consideration the mean aver-age annual increase in demand of the last three years for oil, 2.6%, for natural gas, 3.9%, and for coal, 6.6%, then their respective reserves? lifespan are calculated to be 27, 34 and 38 years. Without taking into account their annual increase in demand, lifespan increases to 38, 67 and 161 years respectively. Since zero increase or perpetual increase in energy demands on finite resources is unrealistic the selection of the most suitable energy commodity for power generation rests upon the law of supply and demand of each commodity. This defines its price hence its selection for the production of cheap electricity. When the ratio of supply to demand is less than one, peak production is achieved. Any further increase in demand results in price increase to quench its demand. The Association for Oil and Gas Peak (ASPO) has calculated that when oil demand exceeds 84 million barrels/day, Peak Oil Production will be attained thus prices will start to increase in order to even demand with supply. Correspondingly, Gas Peak Production is expected to take place when demand exceeds 9.1 or 10.2 billion cubic meters/day. Peak Oil production has been calculated to take place in the current year, 2006, while Gas Peak production is estimated to take place between 2020 and 2025 provided that gas will not cover the energy deficit created from the lack of oil otherwise Gas Peak production could arrive as early as 2010. The use of coal for power generation is considered a better alternative than oil and gas if new combustion technologies with an energy efficiency of 43%, Germany, and 47%, Denmark, are adopted. These not only extend the lifespan of coal reserves but reduce also CO2 emissions by 25% and 31%, respectively. In the very near future CO2 sequestration and fixation in deep geological strata will eliminate its emissions thus rendering the use of coal the cheapest feedstock for power generation.

Jan 1, 2006

By K. K. Bhattacharyya

In the Gulf Coast area lignite deposits occur in Texas, Louisiana, Arkansas, Mississippi and Alabama. Lignite has been mined in Texas since the early 1800's reaching a production of over 900,000 metric tons (1 million short tons) in 1910. With the availability of inexpensive oil and gas, production fall to as low as 16,000 metric tons (18,000 short tons) by 1950 (Henry, 1976). With the advent of the oil and gas shortage in early 1970, lignite production began to increase again. The purpose of this paper is to discuss the geotechnical considerations of mining lignite in the Gulf Coast area, particularly Texas and Louisiana. Lignite deposition occurs in unconsolidated sand, silt and clay environments. Extensive sand units saturated with water may be present within the potential mining depths. This paper describes the geotechnical considerations for designing a surface mine in this geographical area. These factors include geology, hydrology, mining method, and equipment utilization.

Jan 1, 1982

By Majid Ataeepour, Ernest Y. Baafi

High level programming languages such ass C, FORTRAN and BASIC have been used in the mining industry to simulate truck-shovel systems. In addition, some special languages for simulation such as GASP, GPSS, SLAM, PROOF and SIMAN are commonly used. The most recent simulation system ARENA uses graphical modelling approach as well as animation notion. In this paper, the main elements of ARENA required to perform a truck- shovel simulation and to view the simulation results by means of the model animation are presented. The layout of the haulage system including shovels, trucks and dump sites was generated using draw tool in ARENA. All the components of the haulage system were represented by graphical modules. Animation tool was used to depict the performance of the haulage system as the simulation progressed.

Jan 1, 1996