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By S. K. Das Gupta

The rock laterite was first discovered and described in the State of Kerala, India in 1800 A.D. by Francis Buchanan. It had been used here, and elsewhere in India, for many centuries as a building stone, but in Buchanan's time it was not known that some of these laterites were highly aluminous and could be processed to produce alumina. After World War I India started searching for bauxite reserves with a minimum grade of at least 50% A12O3. By 1960, it was estimated that India had a potential reserve of 245 million tonnes of bauxite, about 10% of which was in the "Proved" category. Subsequent geological exploration now reveals that India has an overall resource of more than 2 billion tonnes of aluminium ore, not all of it bauxite, as defined by earlier geologists. In this paper, the geology, resources and distribution of bauxite and aluminium ore throughout India are described. The generalised stratigraphy, typical laterite and bauxite profiles and summary of the resource position are shown in the attached Tables 1 to 8. It is generally agreed that a tropical to sub-tropical climate, intermittent wet and dry season, good permeability of country rock and suitable drainage, as well as physiographic and ground water conditions are important in the development of bauxite.

Jan 1, 1984

By K. L. Myers, R. Espell, C. Deringer

Construction of the AA Pad reclamation was completed in the fall of 2000. Seeding of the ET cover began in the late fall of 2000 and continued through May of 2001. On Saturday afternoon, June 1, 2002, a large, very localized thunderstorm struck the reclaimed AA Pad site. Eyewitnesses present at the time described a dark storm cloud parked above the site for less than half an hour. Average rainfall intensity was measured to be 122 mm (4.8 inches) per hour and peak rainfall intensity was estimated to be 213 mm (8.4 inches) to 259 mm(10.2 inches) per hour. At the time of the storm, the construction was less than two (2) years old and the vegetation had only a single season of growth. The entire period from the end of construction until the date of the storm was a drought period with below normal precipitation. Other than a few small snowmelt events, there was no precipitation event large enough to produce any significant flow in the channel network. Therefore, the very first significant runoff event was the extreme event of June 1, 2002. The storm essentially represents a large-scale field test of the design concepts used at the AA Pad site. Shortly after the storm, data was collected and analyzed with the intent of learning as much as possible about the performance of the cover system design with the expectation that the newly acquired knowledge might be utilized in future designs to further improve the performance of similar cover systems during extreme events.

Jan 1, 2003

By A. H. Shapiro, W. –F. Leung

A decanter centrifuge of novel design was developed for the dewatering of fine-solids slurries having micrometer-range particles that form pastelike, flowable, hard-to-dewater cakes. The design combines a compound beach with a cake flow control structure that allows expressed liquid, from the cake in the dry beach region to be returned to the liquid pool while maintaining a high-solids throughput. To provide optimal performance with various operating parameters (i.e., feed rate, centrifugal gravity, pool, differential speed, concentration of feed solids and slurry type), the cake flow control is adjustable. The second part of the beach is preferably at a zero angle. Tests showed that the new design allows increases in solids dryness and solids throughput. Key words: Dewatering, Centrifuge, Slurry, Fine particles, Beach decanter, Cake-flow control

Jan 1, 2003

By Angus Campbell, Michael J. Gobla

Numerous techniques for treating, controlling, and preventing acid rock drainage have been applied at the Summitville Mine Superfund Site. Challenging aspects of the remote mine site include the wide-spread occurrence of acid-generating soils and rocks, extensive surface and underground mine workings, and a cold and wet climate. Water treatment was an immediate necessity when the Government took control of the abandoned site in December of 1992. Subsequent reclamation activities have emphasized prevention and control of ARD to minimize future water treatment requirements. A combination of conventional, innovative, and experimental methods are being applied to successfully mitigate ARD at Summitville.

Jan 1, 2000

By Michael J. Friedel

As part of a study aimed at understanding the hydrology of in situ leach mining (ISLM), the Bureau of Mines, in cooperation with the Cyprus Casa Grande Corporation and the University of Arizona, is investigating dynamic transmissivity conditions during ISLM of a copper oxide ore deposit. Spatial and temporal variations in ore zone transmissivity during two years of ISLM operations at the Cyprus Casa Grande mine are evaluated during sixteen intervals of steady-state injection and recovery well operation. Direct inversion of an analytical hydrologic model is used to obtain estimates of transmissivity at 58 well locations during these intervals. Univariate statistical and geostatistical methods are used to describe the temporal and/or spatial relationships that exist between transmissivity and other ISLM parameters, including average well injection pressure, average sulfuric acid concentration in leach solution, and the relative configuration of injection and recovery wells. Average transmissivity during the sixteen steady-state time intervals varies between 6.00 x 10-6 m2/min. (6.46 x 10-5 ft2/min.) and 3.61 x 10-8 m2/ min. (3.89 x 10-7 ft2/min.). A trend toward decreas¬ing transmissivity is evident during two year of ISLM operations. This decreasing trend is found to correlate with a decreasing sulfuric acid concentration in injected leach solution, and suggests increasing geochemical precipitation within the deposit. Geostatistical analyses reveal a dynamic and anisotropic transmissivity structure within the target ore zone, that is dependent upon spatial and temporal changes in injection pressure and well configuration.

Jan 1, 1992

By S. K. Kawatra, Harrison R. Cooper

In the last 30 years, on-¬stream slurry analyzers have proven to be of great use in the control of mineral processing circuits. This review discusses the two most popular methods, x-ray fluorescence and neutron activation analysis, and also considers techniques which are still under development.

Jan 1, 1986

By Miguel N. Herrera, Abbas H. Mirza, Fiona M. Doyle

The standard test methods used to determine the pyrite content of coal and mineral wastes, and their propensity to release acidic drainage, are critically reviewed. In addition to analysis of total sulfur by combustion, test methods using selective oxidation of pyrite by HNO3 and H2O2 are available. The oxidation kinetics of pyrite vary appreciably from sample to sample, and it is difficult to ascertain whether complete dissolution has occurred in heterogeneous materials. The reliability, reproducibility and suitability of different standard test methods were studied, using well characterized ore and coal pyrite samples. The kinetics of pyrite dissolution were also investigated. The results are discussed in terms of the fundamental chemical and physical characteristics of each sample, and the implications for waste characterization are considered.

Jan 1, 1992

By Paul S. Murphy, Eric W. Oehrke

INTRODUCTION The global market for sulphur has experienced dramatic structural shifts during the past 10-15 years. After a number of years of dominance as sulphur suppliers, the world's Frasch producers were confronted with large increases in nondiscretionary sulphur production from sour crude oil and gas, while escalating energy and exploration costs reduced the economic incentives to replace dwindling sulphur reserves. Sulphur demand also experienced substantial growth, but the majority of this increase was filled by nondiscretionary production. The result was essentially flat demand for Frasch sulphur during this period. This paper briefly summarizes Freeport Sulphur Company's outlook for global supply and demand for sulphur through the year 2000, and examines in more detail the history and anticipated shifts in trade patterns. World trade in elemental sulphur (brimstone), despite year-to-year fluctuations, has been on an upward trend in recent years, and should continue to grow through the end of this century. The type (discretionary vs. nondiscretionary) and location of forecast sulphur supply sources has potentially broad implications for the world's Frasch producers, as they compete in a world market which is increasingly supplied by non-discretionary production. SULPHUR DEMAND Sulphur is a versatile and essential element used in a wide variety of manufacturing processes. Almost 90% of world sulphur consumption is in the form of sulphuric acid. The relatively low cost, ready availability, and physical and chemical properties of sulphuric acid make it the most economical acid for a number of chemical processes. Although sulphur is used in the manufacture of many products, the largest consumer by far is the phosphate fertilizer industry. The majority of sulphur demand growth over the past 30 years has occurred in this area, and today it accounts for nearly 65% of global sulphur consumption in all forms. Due to the relative importance of phosphate fertilizers, sulphur demand is typically discussed in terms of fertilizer and non-fertilizer (or industrial) uses, and this approach will be followed here. We at Freeport believe that global consumption of phosphate fertilizers should grow at an average annual rate of about 3.5% through the year 2000, which is roughly equal to the growth rate experienced during the past ten years. The basic assumption underlying this forecast is that world population will continue to grow significantly, while the total acres of cropland will grow only slightly. Therefore, in order to feed a growing population, higher crop yields will be necessary, which in turn will require the increasing use of fertilizers. This expected growth in phosphate consumption will, without doubt, fluctuate from year to year, and we Frasch producers have painful memories of the large dip in demand during 1982-83. However, we believe that the fundamentals for growth are very good, and that future demand will move back onto the historical trend line. In the recent recession the use of sulphur in the non-fertilizer or industrial sector dropped sharply, and it now appears that future growth will not return to the old trend line. Most of the non-fertilizer uses of sulphur and sulphuric acid involve older industries which are very mature, such as oil refining, steel, pulp and paper, pigments, etc. The use of sulphur in some of these industries is expected to exhibit little or possibly even negative

Jan 1, 1986

By John S. Thayer, Frederick E. Brinckman, Kenneth L. Jewett, Gregory J. Olson

Interest and research in biorecovery of metals has focused mainly on cell-based metal leaching and precipitation. However, production of non-enzymatic metabolic products by microorganisms related to metals bioprocessing also deserves attention. For example, it is well known that biogenic inorganic (e. g. H2S04 ) and organic acids play a role in metal dissolution. There are other metabolic products of microorganisms which can catalyze useful metals transformations. These include methylated metabolites such as alkyl halides which can dissolve metals from ores and also reduce certain metal ions in solution to pure metallic particles. This paper describes some of our research on metal dissolution and precipitation by such metabolites. Examples include the production of high purity elemental metal particles of gold, platinum and palladium by volatile metabolic products.

Jan 1, 1989

By Kevin DeSomber, Scott Bird

Larger grinding mills continue to utilize large gear-driven drives or electrical wraparound drives. The panel will include presenters from operations with large mechanical and electrical drives. JIM HANDLEY: Before we get to the third and final session, I want to introduce my co-conspirator for this session, John Mansanti. John is manager of milling with Newrnont Gold Company, Carlin, Nevada, and was very active in securing participation in this innovative symposium. I'm Jim Handley and I'm with Cyprus-Amax Minerals at the Sierrita copper and molybdenum mine. Our third presentation is titled "Geared Up or Wrapped Up?" I hear this topic discussed, but never at great length. I think that's because the opinions are fairly strong and diverse, and people generally aren't reinforced properly in their arguments. The first person to enlighten us on this topic is Scott Bird. He has more than 20 years with Kennecott, is a graduate in metallurgical engineering from the University of Utah, and is currently operations superintendent and deals with this phenomenon every day.

Jan 1, 1998

By Robert C. Dunne, Jeffery P. Vaughan

The Archean ores of Western Australia are in total the largest producers of gold in Australia. In addition to numerous small and medium sized deposits, the province also contains the giant Kalgoorlie Golden Mile deposits. A variety of different gold ore mineralogical associations has lead to the development of a number of different processing routes for both refractory and non-refractory ore types. Intense weathering and lateritization of Archean greenstones in the semi-arid Yilgarn region have resulted in the development of a deeply oxidized profile (60-100m) above most sulphide orebodies. Residual and re-deposited supergene gold within iron oxide/silica gangue of this zone responds well to CIP, CIL, heap and vat leaching techniques. Although gold is easily liberated in principal from oxidized gangue, in practice recoveries are sometimes affected by iron oxide coatings on gold grains, and by clay minerals which can interfere with plant performance. Refractory ore types in the Eastern Goldfields fall into three main categories - pyritic, arsenopyritic and telluride-bearing. Pyritic ores may be either free milling or require roasting. The difference appears to depend largely on whether gold occurs along grain boundaries or fractures, which can be liberated by grinding, or whether gold occurs as inclusions within pyrite grains and therefore cannot be satisfactorily liberated by grinding. Arsenopyrite bearing ores are not well understood and are complicated by what appears to be a variable degree of gold solid solution, in addition to included gold. Gold occurring in complex gold-silver telluride assemblages has traditionally been recovered by roasting in the Eastern Goldfields.

Jan 1, 1987

By Hassan El-Shall

The results of laboratory and pilot plant testing of a newly developed process to dewater waste slurries from different industries are presented. Data indicate that an increase in solid contents from 6% to over 30% can be obtained in few minutes retention time in comparison to several years as required by currently used technologies. The economical as well as the environmental impacts of such process are discussed.

Jan 1, 1992

By J. D. Miller

Flotation chemists have long sought to unravel the mechanisms of carboxylate collector adsorption by semi-soluble salt minerals. In particular, the adsorption density of adsorbed carboxylates, adsorption kinetics, speciation (chemisorbed, physisorbed), orientation, and conformation are of interest. Given the importance of these phenomena in establishing the hydrophobic state at a mineral surface, in-situ surface spectroscopy studies certainly are justified. Such measurements traditionally have been difficult to perform. However, beginning in the late 1980s, a Fourier transform infrared (FTIR) spectroscopic technique was developed that has allowed for the acquisition of a wealth of detailed information concerning carboxyiate adsorption in semi-soluble salt flotation systems. The technique, internal rejection spectroscopy using single-crystal internal reflection elements, is reviewed, as it applies to semi-soluble salt flotation systems.

Jan 1, 1999

By Howard Brown

High purity, high brightness limestone deposits in the San Bernardino Mountains and Mojave Desert region occur in upper Paleozoic carbonate rocks which are part of an upper Precambrian and Paleozoic sequence that unconformably overlies crystalline basement. The Paleozoic strata are divided into formations and members, and correlated with strata of the inner Cordilleran miogeocline. The region has been affected by multiple Mesozoic intrusive, contact, and regional metamorphic events. Structure is complex, and includes polyphase Mesozoic folding and thrusting, and complex Cenozoic structures. The area continues to be seismically active. High brightness (white), high purity crystalline limestone deposits are uncommon because their formation is dependent on several geologic processes which include; 1) depositional environment, 2) contact and or regional metamorphism, 3) folding and faulting, 4) uplift and erosion, and 5) preservation through geologic time. The complex geologic history of the San Bernardino Mountains and Mojave Desert region has allowed the formation of several large high brightness, high purity limestone deposits which are currently being mined or will be mined in the future. Specialty Minerals, Inc. (formerly Ptizer), Pluess-Staufer (California), Inc. and Partins Limestone, Inc. produce high brightness, high purity limestone from several quarries in the San Bernardino Mountains. These active mines combined with undeveloped deposits controlled by Pluess-Staufer in the San Bernardino Mountains, New York Mountains, and Bristol Mountains in the Mojave area, contain proven and or indicated reserves sufficient to sustain production through the 21st century Detailed geologic mapping, intimate knowledge of stratigraphy, recognition of complex structures, sampling, drilling and assay data, are proven tools in the discovery and delineation of high brightness, high purity limestone deposits in the San Bernardino Mountains and Mojave Desert region of southern California.

Jan 1, 1995

By D. C. Rotherham

The Kidston gold discoveries were originally made about 1907, and by 1934, 1.76 Mg (62,000 oz) of gold had been produced from placer and lode mining of higher grade, most¬ly oxidized gold ore. As mining in the lode ore penetrated deeper, costs increased and the world gold price stagnated. The lode or underground production averaged close to 6.9 g/t (0.2 oz per ton) Au for the 201 kt mined. No mining or development took place from 1934 until 1965. Kidston's high grade ores were exhausted by 1934. From 1965 to 1976, exploration had developed 3 Mt of about 3 g/t (0.88 oz per ton) Au. Placer Pacific acquired rights to the property in 1976 and began a geologic and engineering study of the district. It was clear that the deposit had the potential for becom¬ing a large-tonnage, low-grade producer. However, explora¬tion had to discover the tonnage and grade and engineering needed to solve the obstacles of production costs. Bulk material handling problems were addressed by Placer's wide experience in open pit mining, and the increase in work index accompanying deeper ores was handled by Placer's metallurgists. The matter of power for the operation was solved by engineering studies. These showed that power could be generated and brought in economically. The price of gold also increased after 1976, and this helped in the economic analysis. The Kidston discovery since 1976 is really a combination of good exploration geology and careful engineering plan¬ning that overcame the obstacles presented by ore characteris¬tics and the location of the deposit. The attached paper by Harry Mustard is an extract of his honors thesis and explains the deposit geology.

Jan 1, 1990

By F. L. Wilke

Underground mining is a very complicated and complex industrial activity. The uncertain and, in most cases, the incomplete knowledge of the geological and mineralogical nature of the deposits can cause unforeseen difficulties. For a safe and uninterrupted operation, in addition to good planning and scheduling, reliable and up-to-date monitoring and control of all processes and conditions become necessary. Today, this is even more important in view of increasingly difficult working conditions, poorer grades, and more complex and expensive machinery. In short, large capital investment and higher risk of financial losses are involved in modern-day mining operations. Monitoring and control of the underground mining process has become a very complex and difficult task in itself. Many different systems are available, and the correct choice .is of utmost importance from both the economic and safety points of view. This chapter will deal with aspects of underground production monitoring and control. There are, however, many other areas of equal importance which are covered in an excellent manner in a hand- book by Olaf (1976) on monitoring and control of underground operations.

Jan 1, 1979

By Ross W. Smith, Xiapeng Zheng, Peggy J. Arps

The adhesion (and de-adhesion) of Bacillus subtilis to dolomite was determined under a number of conditions of initial concentration of the organism, agitation, mineral particle size and temperature. Rate equations curves for both adhesion and de-adhesion were constructed, with the rates of de-adhesion being about half that of adhesion. From the temperature data the energy of adhesion was determined to be about 1.02 kcal/mol. Adhesion of dolomite to B. subtilis follows a Langmuir isotherm. Equilibrium constants, adhesion capacity and Gibbs free energy of adhesion of B. subtilis to dolomite (at pH 6.6) were determined. These values were compared to similar data for adhesion of B. subtilis to apatite and dolomite.

Jan 1, 2002

By Jozef Descour, Kazunori Nishioka, David M. Neil

Designers, engineers, and contractors are using three-dimensional seismic tomography for geotechnical site investigations and during tunnel excavation for hard rock and soft ground applications. Utilizing multiple types of seismic signals produced by a TBM, drill, or impact breaker, the reflection of different velocity features are processed into a holographic image of the actual structure to be encountered. The Mill Creek Phase 3 alignment in Cleveland, Ohio, was imaged to define existing conditions along a 1,200-ft section of a proposed 6.1-m (20-ft) diameter CSO tunnel and, specifically, a zone of expected anomalous conditions where drilling was inconclusive. In Japan, Kajima Corporation used TRT™ to image a number of tunnels including the Fujikawa and Kanaya tunnels in a combination of methods to map structural features along the alignment.

Jan 1, 2001

By Alice S. Allen, James Paone

SURFACE SUBSIDENCE IN MINING The consequences of subsidence are becoming progressively more serious as the consumption of an ever- increasing quantity of minerals conflicts with the needs of an expanding population for surface land area. The inevitable result will be an increase in the amount of land area on which undermining is restricted because surface subsidence must be prevented. Designation of land areas that may be undermined, provided that subsidence is controlled and kept within specified limits, also will increase. The decisions as to which land is to be used for urban, agricultural, or other purposes clearly involve considerations that go far beyond the scope of mining technology. Under the authority assigned to the US Bureau of Mines (USBM) by the Organic Act (May 16, 1910) and its succeeding amendments and pursuant regulations (30 U.S.C. 1-1 1 ), the Bureau conducts scientific and technologic investigations concerning mining and its related problems. Subsidence-control demonstrations that have been conducted under this authority include projects in Wyoming, West Virginia, Illinois, and the Pennsylvania anthracite region. The problenls for technology arc to devise methods for extracting minerals with controlled subsidence in varying geologic settings and for calculating or predicting the amount, extent, and characteristics of the subsidence that accompanies the extraction of our principal minerals mined by high-tonnage methods so that logical choices can be made from the possible alternative approaches. Where underground minerals and fuels are mined and removed, the voids that are created underground generate strong imbalanced stresses in the surrounding and overlying rock strata. The resulting readjustments in the rock masses may cause subsidence of the ground surface. Subsidence implies vertical collapse, because the most conspicuous component of movement is downward. However, the downward component is accompanied by differential horizontal strains that may be more damaging to man-made surface structure.; than the more apparent vertical displacements. SUBSIDENCE CONTROL The most widespread method of alleviating potential subsidence problems in undermined areas has been to backfill mine voids with mine refuse or some other in- expensive material that provides lateral support to the remaining mine pillars and vertical support to the mine roof and overburden. Most USBM backfilling work has been conducted jointly with the Pennsylvania Department of Environmental Resources in the anthracite region of northeastern Pennsylvania. These joint projects were conducted under the authority of the Anthracite Mine Drainage Control Act of July 15, 1955 (Public Law 84-162, as amended), and the Appalachian Regional Development Act of 1965 (Public Law 89-4. as amended). In addition to the Appalachian and mine-drainage projects, the Bureau has either conducted or participated in demonstration projects to develop the "pumped- slurry" method of backfilling mine voids. Three of these projects were conducted in Rock Springs, WY. The first was a field test of the pumped-slurry technique, conducted in 1970 under the combined participation of the City of Rock Springs, the US Department of Housing and Urban Development, the Dowell Div. of the Dow Chemical Co., and USBM (Candeub, Fleissig, 1971). The objective was to demonstrate that a large quantity of sand could be hydraulically injected under pressure through a single borehole, and that filling of the mine voids would be essentially complete. In the earlier "blind-flushing" methods, involving sluicing material through boreholes by gravity, quantities per injection hole ranged from 15 to 765 m3 (20 to 1000 cu yd), and the mine voids were only partially filled. In the first test of the pumped-slurry method, approximately 14 900 m (19,500 cu yd) of sand were injected success- fully through a single borehole. Subsequent information obtained through 43 monitoring boreholes indicated that mine voids below 11 330 m2 (2.8 acres) had been filled. As a result of the successful initial test of the pumped-slurry process, USBM conducted additional backfilling demonstration projects using the new technique. The first full-scale demonstration was carried out in the Green Ridge section of Scranton, PA, between 1972 and 1974. This project proved the feasibility of using the new hydraulic-injection technique to back- fill dry mine voids, as well as flooded voids, and it demonstrated that crushed anthracite refuse could be used as easily as sand in the process. Stabilization was pro- vided for about 202 300 m2 (50 acres) of Scranton, having a population of approximately 1000. Additional demonstration projects at Rock Springs, WY, between 1973 and 1975, resulted in the stabilization of about 364 200 m2 (90 acres). The work was necessary to preserve the physical and economic well- being of the city, because there have been numerous occurrences of subsidence during recent years. A demonstration project completed in 1976 in Rock Springs brought the total stabilized area in that city to 647 500 m2 (160 acres). At a cost of about $3,000,000, a population estimated at 7000 persons and property values exceeding $18,000,000 were protected. Presently. USBM is participating in subsidence- control projects involving backfilling in Pennsylvania, Illinois, and West Virginia. Eleven demonstration projects were in progress by USBM in 1977-eight in the Pennsylvania anthracite region and three in bituminous areas of West Virginia (one) and Illinois (two). The estimated total property value is over $100,500,000, and the total cost of the projects is expected to be nearly $20,000,000. The demonstration projects are designed to adapt the pumped-slurry technique to a variety of subsurface conditions, to increase efficiency, and to reduce costs.

Jan 1, 1982

By Mark R. Rybak, James Delmonte, Travis Hartman

The City of Phoenix, Arizona designed a 7.2 km (4.5 mi) long water transmission main from the South Mountain Reservoir to the Ahwatukee Foothills Reservoir to address the growing demand for drinking water in the southeast valley. The pipeline design called for a bored tunnel in a very environmentally sensitive area. The Reach3B contract included an 2.44 m (8 ft) diameter TBM excavated tunnel, 1,847 m(6,060 ft) in length. The geotechnical investigation revealed that the tunnel would likely pass through zones of loose to moderately cemented soils (caliche). The primary tunnel support would consist of rock bolts, circular steel ribs, hard wood lagging, and mine straps. A TBM that could handle the ground conditions and allow for efficient ground support installation was required. This paper describes the construction of a small diameter rock tunnel in challenging ground conditions.

Jan 1, 2003