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By D. F. Malan

This paper describes the development and implementation of amine-wide continuous stability monitoring system at the Declines Section, Anglo Platinum Union JV. The Declines Section at Union JV experienced a number of large panel collapses during 2005 and 2006. As well as posing a major safety risk, the panel collapses had a major effect on production since the Declines Section is a semi-mechanized operation. The collapses would often extend into the mechanized strike roadways, resulting in a loss of access to both current and future production faces. The collapses have been largely overcome owing to a change in support design and the implementation of a mine-wide stability monitoring programme. This paper describes the precursors to collapses, which were identified using continuous closure measurements and the remedial measures taken. It also outlines the design and introduction of a robust and reliable monitoring tool, which is now used on a mine-wide basis to provide early warning of large-scale collapses.

Jan 1, 2010

By D. N. Madge

A survey is given of production scheduling systems currently in use or contemplated for future use in Cominco operations. Emphasis in this presentation is made on the chain of decisions that are made with the help of mathematical programming models. Some attention is devoted to the structural properties of the models.

Jan 1, 1966

By PAUL M. Tyier

NOW that analytical chemistry has gone so far to debunk early misconceptions about minerals, the fact that the light of exact knowledge still fails to illuminate many dark corners is often overlooked. By combining the skills of the physicist with those of a chemist, the identification of minerals has become an exact science and the presence of even minute traces of impurities and extraneous elements is readily revealed by spectrographic means, Granted that we can learn all there is to know about the composition of a substance and even about its physical propertied (which latter assumption is somewhat far-reaching) it still does not follow that we clearly understood its commercial designation or utility.

Jan 1, 1941

By Yuezhen Zhou, Zewei Liu, Dachun Liu, Chongfang Yang, Wenlong Jiang, Fansong Liu

A novel process that the combination of vacuum decomposition and acid leaching was proposed. The influence of distillation times, diameter and thickness of the feeding material on the mass fraction of Molybdenum (Mo) and sulphur (S) in residual was investigated. The influence of leaching temperature, leaching time, concentration of hydrochloric acid solution, and ratio of liquid to solid on leaching rates of Mo and S in acid leaching process was also investigated. Due to the fact that SO2 emission happening in the long process of traditional molybdenum metallurgy could be avoided in this novel method, this combination process was environmentally-friendly. Molybdenum powder was obtained through handling molybdenite concentrate under the optimal condition parameters, and the mass fraction of Mo reached 98.29 wt%. So it's feasible to produce molybdenum powder from molybdenite concentrate by using this new method.

Mar 1, 2017

By Ernesto de la Torre, Karla Velín, Alicia Guevara

"The following study shows the improvement and simulation of a gold recovery plant of 24 t/day of capacity by gravity concentration, flotation and leaching. The ore processed had grades of 6 g/t Au, 15 g/t Ag, and 0.69 %Cu with the mineralogy consisting of 2 %chalcopyrite, 12 %pyrrhotite, 7 %plagioclase and 50 %quartz. The recovery process starts with crushing the ore followed by grinding it further in a ball mill. The ground ore is then concentrated in a Falcon centrifugal concentrator with concentrate being processed by amalgamation process. Gravity tails are sent to a flotation circuit where the copper minerals and some gold are concentrated. Lastly, the flotation tailings undergo cyanidation for gold recovery. Currently, the overall recoveries are 82.8 %Au, 49.6 %Ag and 99.1 % Cu. The optimization was developed in the laboratory using a Wilfley table by gravity concentration. Flotation tests in the laboratory were performed using potassium amyl xanthate and pine oil. Lastly, cyanidation was then performed on the flotation tailings. The results showed the optimum concentration of sodium cyanide in cyanidation is 2 g/L, which produced an increase in gold recovery from 30% to 44%. The reduction of diameter particle from 132 to 80 µm also produces an incremental recovery of gold and silver from 11% to 21% Au and 0.4 to 3% Ag in gravity concentration. Likewise in the cyanidation the recovery of gold and silver has shown a rise from 44 to 62% and 8 to 32% for Au and Ag respectively. However, the flotation method the gold recovery is reduced from 68 to 30% Au by reducing the particle size. Computer simulations using the programs, Moly-Cop and ModSim were performed to determine optimum parameters for the recovery of precious metals at the gold recovery plant."

Jan 1, 2014

By E. Kendall Cork

The traditional financial objective for a single mine company has been to operate as frugally as possible and to pay out most of the earnings as dividends. If the business is cyclical (as it is for most metals) the dividends might fluctuate quite widely. When the mine is exhausted the company disappears. This is still quite a viable strategy for a single mine company. It is not however a viable strategy for the world as a whole. The mining industry is built by mine development companies who can mobilize the people and capital to bring new mines into production. Their skills must include marketing, engineering, finance and other politics. It is very rare for a property to be brought in without the support of a major company that can provide all these services. The exceptions will usually have some other form of big brother support, for example the U.S. government uranium contracts at guaranteed generous prices. The mine development company will seek as a minimum to perpetuate itself by developing new mines in order to replace those which are running out. The more common and more ambitious objective is to grow -- that is to add to its ore reserves and current production by developing more new mines. The financial objectives for that company are very different. Obviously if all the earnings were paid out in dividends there would be nothing left to work with. The first financial policy then is to spend an appropriate amount on exploration for new properties. The next is to retain enough of the earnings to provide the capital for new projects at least sufficient for the equity. There is no magic formula as to what proportion of earnings should properly be distributed as dividends by a growth-oriented mine development company. As a rough rule of thumb distributing half or more will probably leave too little to work on and 30% or so is probably a good balance. However the circumstances differ widely from company to company. It may be useful to set an objective for the rate of growth of a company's earnings. Some have picked rates such as 15% per annum compounded. Others have set a target in real terms which might appear as 10 or 11% plus inflation. Obviously the arithmetic of compound interest is very attractive; however in practice there is much variation. Indeed current returns from existing operations swing widely with the business cycle and there is no assurance that economic new properties will be found according to someone's arbitrary time schedule. For example, Western Mining Corporation Limited in Australia explored for 30 years with little to show for it, but then found the great Australian nickel deposits and more recently the huge Roxby Downs copper. That long dry spell could not have fitted anyone's arbitrary calendar of growth and yet they would not have found such orebodies without that long period of effort. Should they have abandoned the search? Once a new property has been found or acquired there has to be a threshold rate of return on the new capital to be invested against which to evaluate the property's economics. Conventionally this seems to be 15% after tax, a number common in other heavy industries as well. In some cases it is expressed as a lower number plus allowance for inflation. Discounted cash flow analysis is a very useful tool but it does not make the decision. In the end a "go" decision depends on judgment of many factors some of which are numbers used in the DCF calculation whose credibility must be examined. It is curious how frequently investment proposals come in with the rates of return very close to 15%. The project advocates know that a number much less than 15% will not fly and that a number much more is not necessary. With much higher nominal and real interest rates of recent years, even though before tax, logic suggests that the hurdle rate should also rise. The power of compound interest is so great that 20% is very hard to achieve in any cash flow projection but 18% may be a sensible yard - stick. Once again it is remarkable how many project proposals come in with an 18% return. On the record the mining industry as a whole has not been overly restrictive in choosing its hurdle rates of return. This is shown by the abundance of metals in recent years and the failure of metal prices to keep up with inflation. All of the foregoing is standard text book stuff.

Jan 1, 1985

By J. D. Livingston, H. E. Cline

The lamellar-dendritic transition in Sn-Pb alloys near the eutectic composition has been studied at high growth rates. Lamellar structures were found over a substantial range of tin-rich compositions, and this range extended to increasingly tin-rich concentrations as growth rate increased. These results are discussed in terms of stability and competitive-growth arguments. Various experimental and structural limitations to the rate of directional solidification are discussed. The rate of heat removal at the heat sink is the major experimental limitation. ReCENT interet1,2 in the use of fine composite structures produced by directional solidification of eutectic alloys makes it important to determine the range of composition and growth conditions that yield such microstructures. Because increasing growth velocities produce increasingly finer microstructures, it is particularly significant to determine the factors limiting the rate of solidification. Mollard and Flemings3 have shown that composite structures, free of primary dendrites, can be obtained in Sn-Pb alloys of off-eutectic composition. The composition range of composite structures was found to increase with increasing values of G/V, where G is the temperature gradient and V is the growth velocity. These results are in good quantitative agreement with an analysis of the stability of a planar eutectic interface.4 This analysis specifically predicts that over a small range of compositions stable lamellar structures will be obtained even for G/V = 0, hence, even at very high growth rates. The lamellar-dendritic transition in Sn-Pb alloys has also been analyzed with a model based on competitive growth between dendrites and the composite structure.576 This treatment, based on earlier work on organic eutetics,7 predicts that the composition range yielding composite structures in Sn-Pb will increase rapidly at high growth rates. An increase in the composition range of composite structures at high growth rates was recently observed in Cu-Pb alloys near the monotectic composition.8 In view of these results, and the predictions of the stability and competitivegrowth analyses, it was decided to study the lamellar-dendritic transition in Sn-Pb alloys at high growth rates. EXPERIMENTAL Using 99.999 pct pure materials, a series of Sn-Pb alloys were prepared containing 16.8 at. pct to 27.6 at. pct lead. (Eutectic composition is 26.1 at. pct Pb.) Ingots were extruded to 0.175 in. rod, and some rod was drawn to 0.070-in. wire. Directional solidification was accomplished in two different ways, Fig. 1. For growth rates up to 2 x 10-1 cm per sec, a 0.175 in. diam sample was placed in a graphite crucible 5 in. long with 0.250 in. OD and 0.035 in. walls. Samples were melted under flowing argon in a vertical, platinum-wound furnace, and solidified by driving the crucible downwards through a \ in. hole in a water-cooled copper toroid, Fig. l(a). An insulated chromel-alumel thermocouple was imbedded in the center of a representative sample, and moved with the sample during solidification. The local temperature is plotted against the distance travelled by the sample in Fig. 2. As the growth rate increased, the solid-liquid interface moved closer to the water-cooled toroid and the temperature gradient increased. At growth rates above 10-1' cm per sec, heat was not removed fast enough and the sample moved into the toroid in the liquid state. The curve for V = 2 x 10-1 cm per sec shows a plateau caused by incomplete removal of latent heat from the interface, a problem which will be discussed later. To improve the heat removal, the toroid was cooled by nitrogen gas precooled in liquid nitrogen. This allowed successful solidification at rates up to 2 x 10-1cm per sec. Higher solidification rates required still more effective heat removal. Samples 0.070 in. in diam were placed in graphite tubes 0.125 in. in diam with 0.020 in. walls. Instead of cooling by sliding contact with a cooled toroid, these thinner samples were sprayed or directly immersed into water, Fig. l(b). After solidification, samples were stored in liquid nitrogen until they could be examined metallographic-ally. The surface was prepared with a diamond-knife microtome, followed by a light etch. The presence or absence of tin dendrites, Fig. 3, or lead dendrites, Fig. 4, was noted by optical microscopy, usually of a transverse section near the center of the sample. Replicas of the surface were prepared and examined in an electron microscope to resolve the fine lamellar structures, Fig. 5. The structures observed at various compositions and growth rates are summarized in Fig. 6. Composite structures were observed at increasingly cin-rich compositions as growth rate increased. This transition from dendritic to composite structure with increasing growth rate was also demonstrated by solidifying half a sample at a slow rate and then suddenly increasing the growth rate by lifting the furnace and quenching the sample with a water spray. A longitudinal section of this sample, Fig. 7, shows that the tin dendrites, which extended ahead of the slow-moving composite interface, were bypassed by the composite when the growth rate was increased. The range of composite structures at high growth rates was limited by the appearance of primary lead dendrites on the tin-rich side of the eutectic composition. Observation of representative longitudinal

Jan 1, 1970

By Dale Nix

DuRing the past year approximately 400 depth pressures have been recorded in the Yates field. Of these, 315 were "shut-in depth pressures," observed for the purpose of adjusting well potentials without making open-flow tests. The "shut-in depth pressures" were distributed one to each well and determined under as nearly uniform conditions as possible. Therefore, there is a scarcity of data applicable to production problems, other than the adjusting of well potentials. A few of the data obtained have been used in an attempt to solve some of the producing problems. These applications, however, merely indicate partial solutions and their review herein is to emphasize the variety of problems to which depth-pressure data can be applied, rather than to present conclusive solutions. Very little had been accomplished in the development of instruments to determine pressures within the well bore, when it was decided to obtain such information in the Yates field. Through the combined efforts of the Yates Engineering Committee and several producing companies, three methods of determining pressures in the well bore were soon developed: (1) the "compressor" method, (2) the "volume chamber" method, (3) the "depth-pressure recorder" method. "Compressor" Method.—A small volume compressor is used to inject gas into the tubing. The rate of injection is low so that the frictional losses will be reduced to a minimum. During the test, the pressures at the top of the tubing and casing are observed on recording pressure gages. .As the compressed gas depresses the fluid in the tubing, the pressure on the casing decreases while the tubing pressure increases. The tubing pressure becomes a maximum when the fluid level reaches the bottom of the tubing; and the casing pressure usually rises quickly as the gas breaks around the bottom of the tubing. The sum of the maximum pressure recorded at the top of the tubing and the pressure exerted by the weight of the compressed gas column is equal to the depth pressure at the bottom of the tubing. The procedure can be reversed;

Jan 1, 1932

By F. W. Jessen, James N. Howell

INTRODUCTION The determination of cloud points has to date been limited to rather transparent oils, visual observation of the formation of a solid phase being the criterion for the standard ASTM D 97-47 method. The need for a quiclc and simple method for determining cloud points under dynamic conditions for opaque crude oils became necessary in a study of fundamental aspects of paraffin deposition from crude oils. PREVIOUS WORK The determination of cloud points in opaque oils by viscosity temperature curves is fairly new, Young' described a method employing the capillary tube principle. No information exists relative to the determination of cloud points of crude or refined oils under dynamic conditions. Shock' noticed that deposition of paraffin from crude oils took place at temperatures at or below the temperature at which a sharp inflection point occurred in the viscosity-temperature curve. This observation indicates a possible correlation between this temperature and the cloud point of the crude oil. Reistle and Vietti1 have reported that when crude oils containing small amounts of asphaltic materials were heated to temperatures sufficiently high to solubilize these materials and immediately cooled the pour point of the crude oil was lowered as much as 70°F. Sachanen\ asribes this effect to the action of colloidal asphaltenes in preventing the formation of the crystalline structure necessary to maintain the oil in a rigid state. At high temperatures, asphaltenes are peptized, and the paraffin crystals formed at these temperatures adsorb the colloidal asphaltenes on their surface thereby hindering further growth of the crystals. Reistle" found, however, that such heating and cooling of crude oils had no effect upon the cloud points. This latter work dealt with a crude oil of fixed composition, and the question immediately arises as to the effect of varying the concentration of asphaltic materials on the cloud point. APPARATUS AND PROCEDURE All viscosity measurements were made with a Bendix Ultra-Viscoson. The Bendix Ultra-Viscoson, which consists of a vibrating probe and an electronic computer. measures viscosity by exciting a thin alloy steel blade on the end of a probe by short electrical pulses in damped oscillation at 28 kilocycles. The blade vibrates longitudinally with an amplilude of less than 55 micron or 20 millionths of an inch. Energy to protlucc this excitation is generated in he computer and transferred to the probe through the connecting cable. The oscillating blade is magnetostric-tive, i.e., it is capable of transforming electrical energy to mechanical energy in the ultrasonic range. Ultrasonic waves are produced in the material surrounding the blade by the oscillating motion of the blade causing layers of the material to slip back and forth over one another at a known frequency. The electronic computer calculates the energy required to produce the sliding motion which is in turn proportional to the viscosity of the material. Actual values of viscosity times density (centi-poise X grams/cc) are indicated on the computer and a continuous D-C signal is provided which is fed into a type 153 Electronic Recorder (manufactured by Brown Instruments Div. of Minneapolis-Honeywell Regulator Co.) The liquid sample container was fabricated from a Lucite cylinder and jacketed by a Luicite water bath. Early experiments using glass and steel sample containers were not satisfactory. since the Ultra-Viscoson was apparently affected by the alterzltion of the magnetic fields surrounding the probe by stresses set LIP in the glass and steel as it cooled. The procedure for determining viscosity-temperature curves was relatively simple. The temperature ot the sample was raised sufficiently high to solubilize all paraffin and asphalts present. After heating, the oil sample was immediately transferred

Jan 1, 1957

By Suzanne R. Hess-Brittelle, Sharon L. Schulz, Tyler J. Quick, Amy F. Ebnet

"Abiquiu Dam is a rolled earth fill dam with impermeable core located on the Rio Chama in New Mexico. Abiquiu has had a history of excessive seepage through the fractured sandstone abutments since water was first impounded in 1963. The foundation was treated with a single row grout curtain in the cutoff trench prior to placement of the embankment. During the 1960’s and 1970’s, the grout curtain was extended 1,000 ft. into both abutments and sections of the foundation beneath the embankment were regrouted. Grouting of the foundation beneath the embankment required drilling through the embankment. Drilling fluid loss or loss of circulation within the impervious core was observed during multiple phases of supplementary grouting and during verification drilling following the 1970’s grouting program. It is likely that the drilling methods employed for these grouting and drilling programs caused hydraulic fracturing of the impervious core. The fluid losses in the embankment may be related to seasonal shutdown layers in the embankment or benches in the abutment foundations. In addition, it is likely that the impervious core was fractured from grout pressures during installation of grout pipe through the embankment.INTRODUCTIONAbiquiu Dam is located on the Rio Chama in New Mexico and consists of a rolled earth fill dam with impermeable core, controlled outlet works, and an uncontrolled rock-cut spillway. The dam was authorized for flood control and sediment retention and was designed as a dry dam, holding flood pools for relatively short durations. The foundation is comprised of Permian and Triassic age, interbedded mudstones and sandstones that were deposited in an active braided stream system. Sandstones are moderately fractured and have variable aperture and infilling. Generally speaking, joints are near vertical. Abiquiu has had a history of excessive seepage through the fractured sandstone abutments since water was first impounded in 1963. The foundation was treated with a single row grout curtain in the cutoff trench prior to placement of the embankment. In 1966-1968, the grout curtain was extended 500-ft into the left abutment and the foundation beneath a 560 ft. section of the embankment was re-grouted. In 1978-1980, the grout curtain was extended 1,000 ft. into the right abutment, an additional 500 ft into the left abutment and the foundation beneath the right 520-ft section of the embankment was re-grouted. The alignments of these grout programs are shown in Figure 1. Grouting of the foundation beneath the embankment required drilling through the embankment. Drilling fluid loss or loss of circulation within the impervious core was observed during both phases of supplementary grouting and during verification drilling following the 1978-80 grouting program. It is likely that the drilling methods employed for these grouting and drilling programs caused hydraulic fracturing of the impervious core. In addition, it is likely that the impervious core was fractured from grout pressures during installation of grout pipe through the embankment. This paper provides a summary of the drilling and grouting methods used during these programs and the potential for damage to the embankment."

Jan 1, 2016

By Thomas Deschamps

The main objective of this work was to investigate the effect of binder addition on the geochemical properties of surface paste tailings. Nine leaching columns were prepared following different disposal configurations: non-cemented, non-cemented with cemented layers, and cemented .The proportions of cement by total paste weight were between 0 and 1% for a whole column; the maximum amount of cement in a single layer was 2%. The material used was a sulphide-rich tailings coming from a Canadian hard rock polymetallic mine. The columns have been flushed once a week during 30 weeks. The recovered leachates were analyzed for pH, Eh, conductivity, and a wide range of elements. The drainage rates were monitored during the initial disposal as well as after each column flush. The results show that binder addition can improve the whole environmental performances for some of the studied disposal configurations. The disposal configuration consisting of intercalation of three 2% cement paste layers within non-cemented layers (0.66 wt.% of cement for the whole column), and the configuration with 2% cement added only in the two bottom layers (0,44 wt.% of cement for the whole column), showed the best results in terms of water quality and drainage rates.

May 1, 2007

By H. J. Handewith

This paper explores the state-of-the-art of mechanical rock drilling and boring methods in use in the year 2000. It covers the basic mechanisms of cutting tool design and outlines the current understanding of related rock fracture methods. It provides suggestions for future research needs and discusses the mining and construction markets that are driving these needs.

Jan 1, 2001

By T. Lupek, M. Buxton, A. de Jong

"With regard to the EU funded project ‘Real-Time Mining’ a sensor-based acquisition, collection and transmission of data for the resource extraction process will be developed. The key concept promotes the change in paradigm from a discontinuous to a continuous process monitoring. Especially concerning material characterization, machine performance and underground positioning ‘Real-Time Mining’ will provide sensor solutions as well as the interfaces for integration, management and visualization of the collected data for a permanent updating process of the resource model with the aim of near real-time optimization of decisions. On the basis of ‘Real-Time Mining’-Output a permanent monitoring of costs can be performed as well in both, the installation and the production process of a mine. Due to the collected data in terms of machine performance connected with the underground positioning information added with personnel tracking and mine surveys a comprehensive overview of process performance is available. By evaluating those information in a specific manner costs per unit will arise for monitoring and possibly controlling actions. INTRODUCTION By having a look into the future of mineral extraction projects, a new challenge for the Ore Mining Industry will arise in the short and medium term. Due to the depletion of currently mined mineral reserves in addition to the persistently high demand of mineral raw materials, the extraction of complex reserves will be necessary. By characterizing such deposits as not constantly graded and geometrically varying, the extraction process, especially concerning the requirement of a minimized zero-value material handling, will become economically ineffective by utilizing the traditional mineral resource management methods. Regarding the state-of-the-art mineral resource management process along the mining value chain, an intermitted, discontinuous sequence of actions is applied (Figure 1). Recently data will be collected from drill hole cores. These rock samples are analyzed in a laboratory. Based on those analyses a resource model is created whereby unknown data between drill holes is interpolated. This resource model is the basis for all mine planning actions including the selection of the mining method, extraction sequencing and the prediction of the expected performance. With the start of the production, real conditions (concentrations of elements, hardness, stability, etc.) can be observed and measured. As the production process is running accordingly to the above described mine plan, the verification of the initial assumptions happens at the earliest after processing of the extracted material. Even if deviations between the predicted and the actual performance are now recognized, the execution of corrective actions is not possible anymore."

Jan 1, 2016

By Xumeng Chen, Yongjun Peng, Dee Bradshaw

Regrinding rougher flotation concentrates has become a common practice when processing low grade and complex ores. It not only reduces the particle size and improves mineral liberation but also modifies particle surfaces and pulp chemistry due to the strong electrochemical reactions taking place during regrinding. Therefore, the floatability of minerals in the subsequent cleaner flotation is influenced by the regrinding conditions. This paper presents the effect of regrinding conditions on the mineral floatability from both industrial studies in the plant and fundamental studies in the laboratory. Different regrinding conditions were considered, including grinding media, the electrochemical properties of minerals, pulp chemistry (pH, Eh, DO), and breakage mechanisms in tumbling and stirred mills. Results indicate that the selection of regrinding conditions and mill types should not only depend on grinding energy efficiency and liberation but also depend on the surface properties and pulp chemistry produced for effective mineral flotation and separation at the cleaner stage.

Jan 1, 2014

By P. J. N. Pells

A good thing is becoming a bad thing. Rock mass classification systems, that are so excellent for communications between engineers and geologists, and that can be valuable in categorizing project experience, are emasculating engineering geology and rock mechanics. Some engineering geologists have been sucked into thinking that Q and RMR values are all that is needed for engineering purposes, and seem to have put aside what can be learned from structural geology and geomorphology. Many rock mechanics engineers seem to have forgotten the scientific method. This paper attempts to redress the situation by showing how mechanics can be used in rock engineering to design with a similar rigour to that used in the fields of structural engineering, hydraulics and soil mechanics. It also attempts to remind practitioners of what can be achieved by skilled engineering geology.

Jan 1, 2008

The earth is a planet limited in size and limited in total resources. For the forseeable future, it is the only available habitat for mankind. Therefore, it follows that the more we know about our planet the better we can utilize its space and its resources for our well-being now and in the future. But, to accomplish this, we need reliable basic information. Geosciences provide such information. Recently, Dr. M. King Hubbert took note of the important effect of the geosciences on society, on how we think, and how we live. In the first century of modern geology, 1780- 1880, the influence of geology was primarily on how we think, i.e. changing our concept of the earth from one with a short catastrophic history to one that developed gradually over enormous spans of time. In the second century, 1880-1980, the emphasis was on how we live, on expanding the knowledge base so that we could more easily find and utilize the earth's resources. Now, in the third century, i.e. from 1980 towards the year 2000 and beyond, we should concentrate on both how we think and how we live; i.e. how we can better estimate potential global' resources and how we can manage these resources for maximum benefit to mankind. Like other sciences, the geosciences build upon what has already been done. Progress is achieved by using the thoughts, measurements, and observations of past workers, adding to these the insights from new experiments and from new concepts. Geology has its own methodology and approaches; but more than most sciences, it calls also upon the tools of physics, chemistry, mathematics, engineering, and biology to help solve its problems. Today's increasing population, increasing industrialization, and increasing complexity of modern society demand more detailed geoscience information so as to better use the land, reduce geological hazards, provide an inventory of resources, facilitate waste disposal, and prepare for long-term effects such as changes in climate and sea level.

Jan 1, 1986

To concentrate coarse mica particles using a dry beneficiation technique. Approach Concentrate coarse, II berated mica particles using a Bureau-designed system of crushers, screens, and a two-stage zigzag air classifier. How It Works Because mica has a flat plate-like crystalline structure, mica particles are significantly lighter than blocky gangue particles of the same size fraction. Thus an air classification technique can separate the flat, light mica particles from the heavier gangue particles. The ore, which Is first run through a standard jaw crusher, a roll crusher, and a hammer mill to liberate the mica, enters the rougher Zig-zag section through a rotating air lock. See photograph and diagram of a 2-stage air classifier. Airflow through the classifier can be varied according to the size of the particles being separated. The gangue material falls through the airstream of the rougher zigzag section and is discarded as tailings. The mica flakes are carried by the air-stream to the cyclone shown on the right side of the diagram, where they are collected. This rougher mica concentrate is fed to the cleaner zigzag section through another rotating air lock. The mica particles are again carried by the airstream but they are now collected In the cyclone on the left side. The cleaner concentrate leaves the left-side cyclone through a third rotating air lock and is rescreened to remove under-size material missed by the first screening. The final product of this pneumatic process is generally a high-grade mica concentrate. A generalized flow diagram for the pneumatic concentration method Is shown In the second diagram.

Jan 1, 1981

By Thomas Lane Carter

THE history of mining in South Africa differs somewhat from that of other countries in the part taken by the aborigines in the development ?of the mineral deposits. The Spaniards in America, and the fortune-seekers of Australia and New Zealand, found large numbers of natives in these new countries, but the inhabitants did not become willing or efficient workers ill the mines which the white men started. The Kaffirs of South. Africa have not shown the same antipathy to labor, nor do they show any signs of dying out in the presence of the white man's civilization. They are a virile race, and so far the vices of civilization have not killed. them. While it is true that the brain and skill necessary for the exploitation of the mineral resources of this sub-continent-have been supplied by the white race, it is also a fact that most of the rough labor in the development of the mining industry of South Africa has been done by the Kaffirs. The Kaffir tribes differ greatly in their mental and physical capabilities. Compare, for instance, a Zulu of Natal with a Bechuana, or a Xosa of Cape Colony with some of the degenerate tribes of Central or East Africa, and you will find that they have little in common, save that their skin is black and that they do not believe in clothes. As a general rule, the tribe's in the milder, healthier climates are far superior, both in mind and body, to the Kaffirs brought up in the hot malarial sections of Central Africa; and it naturally follows that the black men from the temperate zones of the country, are much finer workmen than the degenerates from less favorable sections: It is universal in South Africa to speak. of the .Kaffirs as " boys." No matter if he is 90 years old, the Kaffir is always a " boy," and in this paper the word " boy " is synonymous with Kaffir.

Nov 1, 1908

By S. Tuylu, D. Adiguzel, A. Bascetin

"In recent years the fact that mining tailings cause serious environmental problems resulted in increasing number of studies about their disposal, storage and usability in various areas. Therefore the new studies about using the tailings for some purposes such as using in shotcrete or producing concrete have been increasing recently. The study is focused on applicability of tailings for producing shotcrete. Under this scope it is considered that mining tailings can bring many advantages in case of that they are used instead of sand, silt or fine aggregate in shotcrete applications. Most important advantages can be listed as decreasing shotcrete cost, decreasing amount if mining tailings to be disposed and the contribution to be provided on sustainable production of sources. The main objective of this study is the investigation of using mine tailing instead of fine aggregate in shotcrete. In this study, 10 shotcrete designs in different proportions were formed, and properties of the mixtures were identified. Then, the experimental results were statistically analyzed, the effects of the amount of the tailing material used on shotcrete properties were presented, and empirical approaches that can be used for the estimation of these properties were developed. INTRODUCTION The disposal of high amount mine tailing on the surface is caused a lot of problems in terms of environmental impact. Unfortunately, it is known that classic disposal techniques such as tailing dam cannot provide a solution these problems. The tailing dams which are usually used in the disposal of mining tailings bring along many problems in terms of cost, environment, and human health. So mine tailings are used in different production such as shotcrete. This technique is becoming increasingly common during recent years. The usability of mine tailings in brick and concrete production instead of cement and fine aggregate has been studied by many studies [1-4]. This situation has been promising for the usability of tailings in shotcrete which is commonly used for ground support especially in tunnels. Shotcrete (sprayed concrete) is applied mainly for construction of tunnels, shafts, renovation works and strengthening of slopes. Main advantage of shotcrete is fast development of strength, which quickly ensures stability of strengthened structure [5]. Shotcrete can be defined as spraying the grout consisting of water, aggregate, cement and optional additive mixture on the desired surface with a compressed air. According to the definition of the American Concrete Institute (ACI), it is the spraying of sprayed grout or concrete on a surface at high speed with air pressure [6]. In recent years, the use of shotcrete for the support of underground excavations is decreased in the mining industry. The design of shotcrete support for underground excavations is a very imprecise process. Strength and pumpability properties of shotcrete are very significant for determining suitable shotcrete design. Flow characteristics of the shotcrete must be determined for pumpability and fluidity of the material."

Jan 1, 2017

By R. J. Visintainer, W. L. Whitlock

"Difficulties with the sizing and operation of centrifugal froth pumps are common and the underlying fluid dynamics are complex. Design and selection often relies on previous experience, offering unreliable guidance for novel applications or unexpected problems. The current paper describes a program of extensive laboratory testing on froth handling centrifugal pumps, covering a range of flows, heads, speeds, viscosity, air content and froth stability. Variations in impeller vane design and the effectiveness of an airlock venting apparatus were also examined. The program resulted in a better understanding of centrifugal froth pump dynamics and insight for the troubleshooting of field applications.INTRODUCTION The Challenge of Pumping Froth In pumping mineral processing froth, the handling of large quantities of air within the fluid is often unavoidable. Efforts to reduce the amount of air present at the pump suction, while always recommended for improving pump performance, may have limitations. Some strategies may also carry an economic penalty, such as unwanted process dilution (e.g. due to water spray or injection), or increased capital cost of equipment due to oversized pumps, sumps and/or piping. Froth pumping losses fall into several categories, as described below and represented graphically in Figure 1. • Density effects: Entrained air reduces the pressure created by the centrifugal pump in direct proportion to the reduction in bulk density. This is not a true “loss”, since the head produced by the pump (in meters of froth), may remain unaffected. However, the reduction in pressure often leads to a corresponding increase in pump speed required to drive the system, which itself leads to increased NPSH required by the pump (NPSHR). Furthermore, by adding a gas phase, the overall volumetric flowrate is increased, assuming a fixed quantity of de-aerated liquid being handled. This leads to increased suction velocity which further reduces the NPSH margin by simultaneously increasing pump NPSHR and decreasing system NPSH available at the pump suction (NPSHA). • Viscosity effects: Increased viscosity introduces an additional factor in some froth pumping applications, such as oil sands bitumen froth. Losses result from increased shear stress within the fluid flow, which increase with flowrate. Viscosity also facilitates the formation of airlock by reducing turbulence and allowing individual bubbles to coalesce more easily within the flow stream. Finally, it increases pump NPSHR by increasing local pressure drop in the vicinity of the vane inlet edges. • Airlock effects: Also known as air binding, it occurs when air or gas coalesces within the pump suction or impeller passages and begins to collect there, held by buoyancy forces within the rotating flow field. In essence, the liquid “floats upwards” towards the pump suction against the outward directed centrifugal forces. The airlock acts as a blockage, with corresponding reductions in flow, head and efficiency. NPSHR also increases, due to increased velocity and distorted streamlines in the flow circumventing the blockage."

Jan 1, 2012