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A rotating disc geometry was used to provide a uniformly accessible surface for a kinetic study of the cementation of cadmium, lead, and silver from dilute aqueous solutions. This work is an extension of studies carried out on the Cu-Zn and Cu-Fe systems for which the reaction rate was found to be completely solution phase mass transfer controlled.When the amount of material deposited was greater than 0·2 to 0·4 mg/cm2 there was an apparent enhancement in rate which is attributed to the formation of a roughened deposit. This same phenomenon was observed in the Cu-Zn and Cu-Fe systems. Again, the rate of reaction of each system investigated was found to be solution-phase mass transfer controlled.

Jan 1, 1971

By P. Venkatraman

Laboratory and pilot-scale test data have shown that the innovative feed presentation of the CrossFlow separator provides improved metallurgy when compared to traditional hindered-bed or teeter-bed classifiers. This design feature prevents excess water from entering the separation chamber and disrupting the overall fluidization flow rate within the teeter zone. Recent side-by-side industrial-scale evaluations have verified that this technology can improve overall efficiency, reduce the cut point of separation, and increase throughput capacity. This paper describes the important features that make this novel separator ideally suited for size classification and density concentration. Test data from heavy mineral, phosphate, and industrial mineral applications are also discussed.

Jan 1, 2005

By Mary F. Koehler

Continuing a program of thermochemical investigation of compounds of to ferroalloy elements, this paper contains ins values of the heats of formation of two sodium molybdates (Na2Mo04 and Na2Mo207) and three sodium tungstates (NO2W4, Na2W207, and NA2W207, and Na2W4013). The experimental method was solution calorimetry. The solution medium was sodium hydroxide solution, except that hydrofluoric acid solution was used for sodium tetratungstate. The heat of formation values are given with reference both to the constit¬uent elements and to the constituent oxides. These data are of prime impor¬tance in the thermodynamic consideration of these substances, as their accumulation includes the most difficult and time-consuming steps toward evaluating the free energies of formation and thus the potential reactivities and thermal stabilities. Except for values for sodium monomolybdate and monotungstate, no previous similar data were contained in literature sources.

Jan 1, 1962

By C. Pattenden

The viability, self-reliance and resilience of small communities are perennial challenges in regional Australia. Recent developments in Australian mining regions seek to govern the minerals industry in a more holistic way that contributes to sustainable futures for affected communities in different contexts. In some areas of the State of Queensland land use conflicts and the cumulative impacts of multiple projects and activities across time and space have come to the fore. In more isolated regions of Western Australia the dominant issues relate to overstretching people, infrastructure and services in predominantly mining towns. In both cases, there is an ambition for regional towns with a strong extractive industry presence to transition into desirable, liveable and affordable cities with a diversified economy. The paper analyses two strategies - the Pilbara Plan in Western Australia, and the Sustainable Resource Communities Policy in Queensland - to identify how these governance instruments are contributing to sustainable development.

Jan 1, 2011

By Anthony Iannacchionc, Jessica Benner, Harold Miller, Megan Witkowski

"Longwall bituminous coal mining has been practiced in Pennsylvania since the 1970""s. Hundreds of longwall panels have been mined during the last 40 years but only 24 have actually undermined Pennsylvania's Interstate Highway System. The impact to interstate highways are summarized in this paper and the factors that influence the magnitude of these impacts are examined.INTRODUCTIONOver the last 30 years, interstate highways in Pennsylvania have been undermined by portions of 21 bituminous coal mine longwall panels. From 2003 to 2008, three of the panel were extracted by the Emerald Mine and six by the Cumberland Mine both in Greene County and both owned by Alpha Resources. Previous assessments of longwall mining under Pennsylvania’s interstates have identified impacts to the highways but no danger to public safety. In general the magnitude and extent of impacts during the recent undermining of Interstate 79 or 179 appears to be similar as those identified in previous studies. The nine longwall panels are among some of the widest in the U.S. They are supercritical in character with overburdens ranging from greater than 152 m (500 ft) to less than 305 m (1,000 ft).The Pennsylvania Department of Environmental Protection (PA DEP) requested that the University of Pittsburgh summarize observations collected by their staff during the recent undermining of 179. Observations and photographs of impacts to the highway were made by PA DEP staff and entered into reports prepared by California District Mining Office (COMO) staff and statements written into the Bituminous Underground Mining Information System (BUMIS) database. In addition to the observations by the PA DEP, the Pennsylvania Department of Transportation (PennDOT) conducted a series of detailed land surveys along portions of the highway undermined from 2003 to 2008. To characterize the subsidence basin fanned by longwall mining. PennDOT information has been analyzed by another research group within the university (Guticrre7, et al., 20 I 0)."

Jan 1, 2010

By D. M. Fraser

"Brunswick Mining and Smelting Corporation Limited operates two mines; one open pit (No. 6) and one underground (No. 12), approximately 20 miles south-west of Bathurst, New Brunswick. Both are massive sulphide deposits containing copper, lead, zinc and silver. The No. 12 property began operation in 1963 and is presently being mined at a rate of 3600 tons per day underground and is in the completion stages of an expansion to achieve 11,000 tons per day underground by the end of 1930.Originally at Brunswick Mining, acid mine drainage was added to tailings and neutralized by an excess of lime in the tailings. A conventional recycle system was established with a biostabilization pond for the treatment of thiosalts, a liming station and sludge settling area for neutralization of acidic water and a final reclaim pond with a pumping station for reclaim water.We found that not more than one third of the reclaim water could be used as it upset the flotation circuit every time it was used. It was established that the mine water and surface drainage were the cause due to oils and detergents in the water. It was also found that the biostabilization pond method Cf thiosalt treatment was not efficient for year round operation in our climate.In 1974, we reviewed the problems and began a 3 phase program to control effluents from the property:"

Jan 1, 1980

By S. J. Schatzel, W. P. Diamond

Longwall mining alters the fluid-flow-related reservoir properties of the rocks overlying and underlying an extracted panel due to fracturing and relaxation of the strata. These mining-related disturbances create new pressure depletion zones and new flow paths for gas migration and may cause unexpected or uncontrolled migration of gas into the underground workplace. One common technique to control methane emissions in longwall mines is to drill vertical gob gas vent holes into each longwall panel to capture the methane within the overlying fractured strata before it enters the work environment. Thus, it is important to optimize the well parameters, e.g., the borehole diameter, and the length and position of the slotted casing interval relative to the fractured gas-bearing zones. This paper presents the development and results of a comprehensive, "dynamic," three-dimensional reservoir model of a typical multipanel Pittsburgh coalbed longwall mine. The alteration of permeability fields in and above the panels as a result of the mining- induced disturbances has been estimated from mechanical modeling of the overlying rock mass. Model calibration was performed through history matching the gas production from gob gas ventholes in the study area. Results presented in this paper include a simulation of gas flow patterns from the gas-bearing zones in the overlying strata to the mine environment, as well as the influence of completion practices on optimizing gas production from gob gas ventholes.

By F N. Baez

This paper supplements a keynote address prepared for the MassMin 2016 conference on mass underground mining methods, including block, panel, inclined and sublevel caving. It advocates for a new cave mining paradigm that takes advantage of a number of new and disruptive technologies or innovations that have evolved over the last 15 years, some of which were initiated by major mining companies such as Codelco. The paper will address the challenges that the industry will be facing in the future as well as possible solutions. As background, the paper summarises the challenges that the industry has faced in the past and how such challenges were addressed. The author acknowledges that given his more than 30 years of experience with Codelco Chile (operations and corporate), aspects of his intelligent mining concept have no doubt been influenced and have matured during his invaluable time with Codelco also as the Head of Technology and Innovation. In the paper, he uses some of the innovations developed within Codelco and by the Chilean Government to illustrate the concept of ‘intelligent mining’.CITATION:Baez, F N, 2016. ‘Intelligent mining’ – the way of the future, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 3–8 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

The term geochemistry - chcmbtry' of the earth - is almost limitless in its implied subject, but of recent years a major trend of research in this field has been towards economic application in the search for mineral deposits, and in particular for those of some ofthe less common elements for which a demand now exists.Geochemistry is in a state of slow transition from a purely descriptive subject to a fundamental science concerned with the relationships that exist between the distribution of the elements in the earth's crust and the physical characteristics of the atoms of those elements. The progress achieved promises a set of basic principles which will relate the atomic characteristics of an element to the physico-chemical conditions that make for its dispersion or concentration. This means that, given a geological map of an areasufficiently detailed for the physico-chemical conditions existing in past geological eras to be deduced, there is the possibility that the relative distribution throughout that area of any element present, and its likely mode of occurrence, could be predicted from a consideration of its atomic characteristics.Since the atomic characteristics of the elements are becoming increasingly well defined by physical research, the attainment of this ideal of prediction depends upon:(a) the strengthening of geochemical theory; and(b) the development of petrological and mineralogical methods of assessing the conditions of temperature and pressure prevailing in geological formations at various stages in their history.The other prime requirement is a d.etailed geological map - a requirement that is all too often lacking.The fact that there has been very little "geochemical approach" to problems of economic geology in Australia should not be taken to mean that there is little point in trying to develop such an approach here in as active and as rigidly scientific a manner as possible. The degree of success that has attended the attempts so far made, to which reference is made below, suggests the reverse, particularly in view of the relatively slight cost involved if the investigations were properly organised on a centralised basis. There are three aspects of geochemistry that are directly applicable to the search for economic minerals.(a) The classic technique of the prospector can be made more sensitive and reliable by the use of modern equipment coupled with the application of geochemical theory to geological and structural data. The case of the rare alkali elements (see below) is givenhere as an illustration of the way in which the distribution of elements can be predicted from the first principles of geochemistry, thereby replacing the prospector's dependence on his "sixth sense" that enabled him to suggest that a certain area of formation was"favourable" for the occurrence of a certain type of mineral deposit.At its best, this sixth sense amounted to an almost subconscious correlation of all relevant associations and typical occurrences of the particular mineral experienced by the prospector during his...

Jan 1, 1950

Physical testing of rock support for rockbursting conditions has been carried out for over 40 years. A review of this testing shows that it has been mostly component?based, rather than actually testing support systems. Further, it is concluded that none of the testing is truly representative of rockburst loading in a similitude sense. Similitude conditions are not achievable, mainly because the real conditions in a rockburst event, such as seismic source location and magnitude, wave frequencies, amplitudes, and interactions, are not all known. Because such information is not available, and because the results of all testing carried out to date have not been able to define, for support design purposes, the capacity of support systems, ongoing physical testing of rockburst support systems is essential. It is essential that the test should simulate, or actually take place in, a supported rock excavation. A rock support system is a combination of individual support components that work together to retain and contain the rock. In doing this, the components are subjected to loading by the rock and to interactive loading between one component and another. It is necessary to prove the capacity of such rockburst support systems by subjecting them to severe loading, as in direct blasting. The direct blasting approach, pioneered more than 40 years ago, probably still provides the greatest validity as a significant test of rockburst support capabilities, even though it does not simulate a rockburst. Direct blast testing of rockburst support systems in a surface environment, such as in a quarry or on exposed rock cutting surfaces, could represent a practical development of the approach, facilitating the execution and monitoring of tests.

Jan 1, 2012

By P. J. Closmann

Steam zone growth as a function of time has been calculated for the case of constant rate steam injection into a preheated reservoir. To simplify the calculation a linear temperature profile has been assumed in the cap and base rock at the start of steam injection. The results indicate that at early times augmentation of steam zone growth due to preheating should be greatest. At longer times the steam zone development becomes close to that calculated with no preheating. INTRODUCTION With the increasing application of thermal recovery processes to recover viscous oil, cyclic steam injection has become important in many large-scale projects. In this process, the cycle of steam injection followed by oil production is repeated a number of times. At the beginning of the second and later cycles, steam is injected into a reservoir that has already been heated but that has lost part of its heat both in produced fluids and by conductive heat loss away from the injection zone. In such a case, the temperature level of the injection zone and the temperature distribution of the surrounding rock will affect the growth of the steam zone developed during the subsequent steam injection. Knowledge of the size of steam zone developed is important in determining the amount of oil displaced and the extent of heating in the reservoir. It is also useful to be able to compute the size of the steam zone for cases where thief zones take most of the injected steam. This paper presents a fairly straightforward method of estimating the steam zone developed in a preheated formation, based on certain simplifying assumptions. Some cases of steam injection into a reservoir at its original temperature have already been considered elsewhere.1-3 Because it is difficult or impossible to obtain an accurate representation of the temperature distribution in the reservoir some time after initial heating has taken place, in this work, a linear temperature profile in the cap and base rock is assumed (Figs. 1A and 1B). The linear profile has the advantage of yielding heat flow equations that

Jan 1, 1969

By Theo. A. M. Salet

The historic centre of one of the most beautiful cities in Northern Europe -Amsterdam - is being excavated to accommodate the new North/South metro line. This new line is due for completion in 2012, and will link the Buikslotermeerplein district north of the harbour, underneath the Central Station and the old city with its gables and picturesque canals, to the commercial centre in Amsterdam Zuid/WTC. Three underground stations are being construction in the old city at Rokin, Vijzelgracht and Ceintuurbaan. The logistics of working in the middle of an historic city are demanding -maintaining tram, vehicular traffic and pedestrian access along narrow streets, providing suitable protection for the public alongside the working areas, arranging adequate delivery routes, as well as monitoring the old and mostly historical buildings for potential settlement. Safety of both the public and adjacent properties is paramount. Diaphragm walling - 1.2m & 1.5m thick and up to 48m deep - was chosen as the support system for the three deep metro stations. Challenging engineering as well as state-of-the-art equipment to construct the diaphragm walls was needed in order to meet the tight working specifications, in the narrowest locations imaginable. Extreme conditions call for innovative solutions.

Jan 1, 2006

The mineral industry of Benin contributed less than 1% of the 1977 gross domestic product (GDP), which was estimated at $500 million.' Other than limestone and salt, no exploitable mineral deposits have yet been discovered in Benin, which has been rated by the United Nations as one of the world's least developed nations. In 1977, the economy was further weakened by petroleum price increases and severe drought. The country continued to depend on foreign assistance, which averaged $20 million per year, to finance development projects. The country's first 3-year plan, which was put into operation in October 1977 after many delays, allocated more than $1 billion to projects in infrastructure, agriculture, and light industry. The most important infrastructure project was the expansion and modernization of the port of Cotonou, valued as an entrepôt port for the transit of goods to the neighboring countries of Niger and Nigeria. Plans called for an increase in handling capacity to 1 million tons of cargo annually, the improvement of port and cargo handling operations, and the upgrading of the efficiency of the Port Autonome de Cotonou (PAC) management system. The $46 million project was to be financed by a consortium led by the International Bank for Reconstruction and Development (IBRD) and including Canada, France, Nigeria, and Abu Dhabi. Construction was scheduled to begin in 1978 and be completed in 1980.

Jan 1, 1981

By Jerry T. Shelby

Surface and underground mining operations require equipment with high power output ratings. Haul trucks, loaders, dozers, and other equipment need increasing horse-power to meet production demands. To get more horsepower out of the engines driving the equipment, most manufacturers use turbocharging. Detroit Diesel puts the number at about 90% turbocharged, while Caterpillar estimates 75% to 80% of all its equipment is turbocharged. Turbocharging increases the power output and overall engine efficiency. But it presents some maintenance and operational problems that were not factors when only naturally aspirated engines (nonturbocharged) dominated the scene. A turbocharger is an exhaust-driven air compressor. Using the waste energy in the engine exhaust, a turbine wheel is driven. This wheel is connected by a common shaft to a compressor wheel. The shaft is supported by two plain bearings, or bushings. As the turbine wheel is rotated, the compressor wheel continually compresses the intake air to the cylinders. Compressing the intake air means that more air can be put into the cylinder to burn more fuel. The more fuel the engine can completely burn or combust, the more horsepower the engine can produce. Even though the turbocharger is a relatively simple device, it is a sensitive engine component. It requires special consideration at engine start-up and shutdown. Being freewheeling and exhaust driven, turbochargers can experience temperatures of 540°C 1000°F) and rotational speeds of more than 100,000 rpm. Due to those temperatures and speeds, lubrication is critical to the operation and life of a turbocharger. The turbo is located high on the engine, with the oil supply running through an external line from the sump. The recommended practice is to start the engine and allow it to idle for a few minutes before any revving or loading. This allows the oil to reach the turbo and properly lubricate the bearings before high rotational speeds are seen. Turbo oil supply lines can be as long as 1.5 m (5 ft). Depending on ambient temperatures and oil viscosity, it can take as long as 30 seconds for oil to reach the spinning turbo. However, as little as five seconds without oil can damage the turbo's bearings, reducing its life and overall efficiency. Lubrication problems seen at shut-down can also significantly affect turbo life and efficiency. Manufacturers recommend an idling period of five to seven minutes before engine shutdown. This allows the turbo to slow down and cool off somewhat to help prevent oil coking and bearing damage. When the engine stops, so does the oil supply. There is very little oil left on the bearing surfaces and in the turbo oil supply passages. The immediate heat transfer from the turbine wheel to shaft, bearings, and turbo body literally cooks what is left. This high heat without oil flow can cause bearing deformation by actually melting some of the bearing material. The rapid oil oxidation and coking will restrict oil passages, damage bearings and shaft. Besides heat soaking, there is another problem. If the turbo is spinning at high speeds when the engine is shutdown, the turbo must spin-down to a stop without oil flow. With the large size of turbos used on mining equipment, this spindown time without oil can be for as long as 10 to 20 seconds. Fortunately, lack of lubrication at start-up and shutdown and the subsequent bearing damage can be prevented by oil injection devices. These devices hold a reservoir of engine oil. The oil is injected to the turbocharger bearings immediately on start-up and for several minutes after shutdown. Oil injection devices are spring loaded, hydraulic accumulators. They are actuated at start-up by a solenoid wired to the starter motor. Engine oil pressure charges the accumulator during normal operation. Upon shut-down and loss of oil pressure, the device provides oil to the turbo for about two or three minutes. With an oil injection device, the engine can be started and immediately driven without fear of turbo damage. Also, an abrupt shutdown will not damage the turbocharger since the device will continue to lubricate for two or three minutes. A word of caution. Be sure the oil injection device provides positive oil displacement (pressurized oil flow). Do not use a gravity-flow device. Unless it is a true accumulator, the device could starve the turbo for oil on start-up, Ask for start-up and shut-down pressures and delivery times before considering installation. Keep the oil clean, and follow the manufacturer's recommended oil change intervals. These intervals are usually shorter than with naturally aspirated engines. Use oil with a CD rating designed for diesel applications. A multiviscosity oil is preferable. Use a synthetic engine oil, such as Mobil's Delvac 1, Gulf's Super Duty II, or Chevron's Sub-zero Fluid. Synthetics have much better flow properties at low temperatures. They also have greater oxidation stability (they can take the high heat of turbo-bearing lubrication. And they produce fewer deposits because they are more thermally stable. But synthetic oils do cost more - two or three times more. One additional point - maintain the air intake system. Since all mining is usually in a dusty environment, air filters should be changed regularly and intake systems should be checked for leaks. All intake air passes through the turbo. Any dirt or abrasives entering the turbo will damage the unit and shorten its life. While mining is a heavy duty business with severe operating conditions, you can get the life from your turbocharger that you expect by following a few simple steps: • equip the turbo with an oil-injection device to provide lubrication on start-up and shutdown; • change the oil and filters regularly; and • use the proper oil-synthetic, if possible.

Jan 3, 1987

By Ike Isagon

Outline 1.Background Sudbury Backfill Operations 2.Alternative Binder 3.Alternative Binder Trial Process Flow Diagram ?Laboratory Results ?Plant Trial ?Final Evaluation and Approval ?Management of Change (MOC) 4.Economics 5.Conclusion 6.References and Acknowledgements

Nov 1, 2011

By D. Craig Camp

conditions. The soils included 65 m of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2, 130 meters of soft clay, silt, and sand not exceeding 30standard penetration test SPT blows per 300 mm, and 220 m of rock ranging between an UCS of 400-600 kgf/cm2. The river crossing, utilizing 1778 mm OD x 19 mm wall x600 mm steel casing pipe without intermediate jacking stations, was part of a seven kilometer liquefied natural gas (LNG) transmission line in South Korea. This 440-m, 1,442-ft, river crossing was microtunneled through three different ground conditions and completed in just over three months. The crossing was achieved with an average of 25 m of ground cover and 15 m of water cover. The Kwang Yang River Crossing was part of a 7 km liquefied natural gas pipeline project for POSCO, a Korean steel producer. The microtunneling machine was custom built for this project. The microtunneling machine selected for this project was tooled with 7 button bits and 2 roller bits. None of the cutter bits were replaced during the drive. Inside the machine, before the spoils laden slurry was pump back to the surface, it would pass through an independent cone crusher. The crusher is placed in the slurry flow to make sure that none of the spoils are so large as to stop the return flow of the slurry. An additional requirement was for the inclusion of a compressed air lock. The air lock was required in the event that the cutter tools required replacement. The cutters were back loaded so that the workers would have access to change the cutters in the event of cutter failure or wear out. No intermediate jacking stations were installed for the drive. The soils included 65 meters of rock not exceeding an unconfined compressive strength (UCS) of 200 kgf/cm2 with production averaging between 7 and 20 mm/minute. The second zone contained 130 meters of soft clay, silt, and sand not exceeding 30 standard penetration test (SPT) blows per 300 mm with production averaging between 80 and 180 mm/minute. The third zone contained 220 m of rock ranging between an UCS of 400-600 kgf/cm2 with production averaging between 7 and20 mm/minute. The steel casing pipe was 1778 mm OD x 19 mm wall x 6000 mm long. The project profile, see Figure 1, shows the soil conditions. The hand written numbers locate just above the pipeline are the production dates. The circled numbers are the 10 pipe joint increments. The project required 74 pieces of pipe to span the440 m drive. Figure 2 and Figure 3 are the jacking information. Figure 3 is a continuation of the information from Figure 2. The top section of the graph is the jacking force. The jacking

Jan 1, 2001

By S. K. Kawatra, H. Haselhuhn

"In many mineral processing applications it is necessary to know the isoelectric points of the various minerals in the ore to properly perform flotation and other mineral separations. However, current zeta potential analysis technology used to determine the isoelectric point of a particle suspension cannot deliver the isoelectric point of each individual mineral, just an average of the mineral system. Traditionally, individual isoelectric points have been gathered by testing pure, synthetic minerals. These values can vary widely depending on the mineral synthesis procedure and the water quality used during the isoelectric point analysis. A more robust approach for determining the actual isoelectric point of a particular mineral in a mixture of minerals is needed. This paper details a method for determining the isoelectric point of an iron oxide mineral in a siliceous iron ore. The method uses a laser scattering particle size analyzer and a pH electrode to determine the pH at which the liberated mineral particles begin to flocculate as pH is decreased. The pH at which the average particle size rises dramatically is the isoelectric point of the mineral with the highest isoelectric point in the ore. This measurement technique was used on natural hematite, goethite and siderite ores as well as a synthetic mixture of pure silica and pure hematite. The results for synthetic hematite mixtures were comparable to literature values.IntroductionRecently there has been an increased interest in the processing of low-grade iron ores (Bolen, 2014; Carlson and Kawatra, 2008, 2011, 2013; Halt et al., 2014; Halt and Kawatra, 2014; Haselhuhn 2012, 2013; Haselhuhn et al., 2012a, 2012b; Kawatra and Halt, 2011; Liu et al., 2014; Manouchehri, 2014; Sandvik and Larsen, 2014; Semberg et al., 2014). The zeta potential of iron ore minerals is a very important and often overlooked aspect of iron ore mineral processing. Zeta potential is the charge at the shear plane of a surface in an aqueous environment (Carlson and Kawatra, 2013). Many ores consist of a variety of minerals differing in zeta potential. This property of a particle surface in water is responsible for either keeping the particles dispersed from each other or flocculated to each other. This is important during many operations such as flotation, desliming and thickening. Zeta potential is primarily a function of the pH of the water and the mineralogy of the particles, though certain ions within the water can also have a significant impact (Haselhuhn, 2012). Consider the following situation: silica (SiO2) particles and hematite (Fe2O3) particles are suspended in an aqueous solution. These two types of minerals have drastically different zeta potentials throughout the pH spectrum (Esumi et al., 1988). In alkaline conditions, both types of particles exhibit negative zeta potentials and will tend to disperse from each other. In acidic conditions (between pH of 3 and 6), silica has a negative zeta potential while hematite has a positive zeta potential, so these surfaces will tend to be attractive to each other and the particles will flocculate and settle. This phenomenon is visually described in Fig. 1. The pH at which the two minerals begin to attract to each other, or destabilize, is near hematite’s isoelectric point. The isoelectric point is defined as the pH at which the surface has a net zero zeta potential (Carlson and Kawatra, 2013)."

Jan 1, 2015

By NEWTON B. KNOX

PERU, lying south of Ecuador and having common frontiers with Brazil, Chile, and Bolivia, includes over a thousand miles of the Andean mountains. The coastal plain is arid and narrow and the Amazonian jungle region is of interest only on account of its oil and gold placer possibilities. The mountain zone, however, here forms one of the world's most highly mineralized regions. The Peruvian Andes, like their Bolivian and Ecuadorian counterparts, form two distinct chains separated by the great Apurimac and Maralion valleys; but these rivers cut through the Eastern range to join the Amazon drainage, and the central valley is missing north of the passes thus formed by these rivers; the localities where the ranges are joined are aptly called knots. In addition, in central Peru, there exists a third range lying to the east of the first two and separated from them by the Urubamba and Huallaga Rivers. The Eastern range, however, is of little importance to the miner for few metal deposits are to be found therein except for the gold mineralization in the South. In general, deposition of metals in the Peruvian Andes accompanied igneous intrusions which invaded the folded Paleozoic and Mesozoic rocks during the Tertiary; thus the ore bodies are all typical of shallow or moderate depths.

Jan 1, 1945

By P. F. Kerr

This is not a conventional professional paper. It deals mostly with personal experiences. These concern a background in applied mineralogy. Your committee asked me to do this. I accepted with a California enthusiasm which has since diminished with the approach of a Chicago winter. Nevertheless, I wish to thank your committee and also to apologize in advance for omissions and inadequate statements, as such a paper must possess. My introduction to applied mineralogy took place in 1922 at Stanford University. Physicists had recently demonstrated that crystalline powders would reflect x-rays in a systematic manner. Professor A.F. Rogers sug¬gested that significant x-ray reflections might be obtained from powdered opaque minerals. With the aid of Professor D.L. Webster in the Physics Department, I constructed an x-ray diffraction outfit. It was a crude affair, but it worked. Starting with 1924, we secured recognizable patterns of a goodly number of ore minerals (1,2,3). Today x-ray diffraction outfits are common, and a card system of mineral identification is constantly used.

Jan 1, 1981

By Robert C. Freas

Dravo Lime Company has opened a new 290m (940 ft.) deep lime-stone mine near Maysville, Kentucky. As the mine was opened there were many unknowns as to the stress relationships within the rock, and their influence, if any, on the selected mining method. Therefore, a system of overlay geologic and structural maps, borehold extenso-meter measurements, and oriented photography was developed for the purposes of monitoring the internal structural relationships of the rock mass. This paper presents a description of the methods used, the observations made, and the conclusions and recommendations made as a result of the initial monitoring program.

Jan 1, 1977