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By S. Zaman, John Bulter, M. E. Defoe, Franklin T. Davis

This section deals with the carbon minerals and materials: graphite, tar sands, gilsonite, and diamond. as well as sulfur and the sulfides of mercury, arsenic, antimony, and bismuth. Table I contains the production figures for each of these commodities in the United States and in the world. Specifications for concentrates are also summarized as are prices for concentrates at the time the section was written. In each chapter an attempt has teen made to describe the more common commercial mineral involved with the commodity, the processes used to recover and concentrate the minerals, as well as geographical areas where these processes are utilized.

Jan 1, 1985

By H. L. Retcofsky

Carbon-13 nuclear magnetic resonance (18CNMR) spectra of nine 2-substituted pyridines, seven 3 -substituted pyridines, and nine 4-substituted pyridines have been obtained and analyzed. Substituents included both electron-releasing groups and electron-with hawing groups. Substituent effects on the magnetic shieldings of the ring carbons, except for those in the 2-positions of 2-substituted pyridines, were found to be quite similar to the effects reported for the monosubstituted benzenes, Thus, at least to a first approximation, the two classes of compounds have similar shielding mechanisms. Shieldings of the carbon atoms in the 5-positions of 2-substituted pyridines and those in the 6-positions of 3-substituted pyridines were found to reflect electron release or withdrawal by substituent groups, The pyridinium cation and the compounds 2,2'-dipyridyl and benzonitrile were also investigated.

Jan 1, 1969

By Greaves J. N

The U.S. Department of Interior, Bureau of Mines, is investigating the treatment of refractory gold ores. Chlorination in the treatment of refractory gold ores is applicable in many low-grade gold operations. When usable, this treatment provides an economic means of consuming sulfides and deactivating disseminated organic carbon. Chlorination, however, is a pretreatment technique that requires the neutralization of the chlorine prior to leaching the ore with cyanide. Research by the Bureau has extended the present chlorination technology to allow for the recovery of gold without the use of cyanide and allow treatment of some ores presently deemed untreatable by gold operators using cyanidation or chlorination/cyanidation techniques. Chlorination without carbon of two carbonaceous ores extracted between 1 and 20 pct of the gold; however, carbon-in-chlorine (CICL) treatments resulted in about 90-pct recovery with a reduction in carbon loading. A statistical design campaign for stripping metallic gold from the carbon loaded in a chlorine environment demonstrated elutions exceeding 90 pct.

Jan 1, 1991

The ability of activated charcoal or carbon to adsorb complex metal ions has been recognized for many years, but it wasn't until the late 1940s and early 1950s that attempts were made to employ carbon-In-Pulp or C. I. P. processing to the recovery of gold. Early plants using the process were those at the Golden Cycle in Cripple Creek, Colorado, the Getchell Mine near Golconda, Nevada, and at the Idria Mine in Honduras. Recovery of the carbon from the pulp was done by screening or flotation, and recovery of gold from the carbon was done by burning the carbon (a very difficult task) or by sending it to a smelter. Unfortunately at the time, the price of gold was still fixed at $3-5 per ounce and labor costs were rising to the point where these mines were no longer able to operate. Consequently, C. I. P. treatment was temporarily forgotten. In the early 1970s, however, Homestake Mining Company at Lead, South Dakota, were being forced by environmental regulations to discontinue the use of mercury for amalgamation in their 7,500 ton per day plant, and at the same time were encountering high labor costs in the slime circuit of the plant, where over 2,000 tons of slimes were filtered each day in Merrill plate and frame filter presses. Shortly before that, researchers of the United States Bureau of Mines had developed the caustic -cyanide method of stripping gold from activated carbon and an electrolytic cell (now known as the Zadra cell) to recover gold from the carbon strip liquor. Homestake and the United States Bureau of Mines then jointly operated a C. I. P. pilot plant at Lead. Results were immediately favorable and a 2,400 ton per day C. I. P. plant was then built to treat the slime fraction of the Homestake ore. (See Au and Ag Cyanidation Plant Practice, Volume I, SME of AIME, 1975. Later, Homestake built a second plant at Creede, Colorado, to treat the slime fraction of the tailings from a silver-lead flotation plant. Next was Duval Corporation's 3,000 ton per day C. I. P. plant at Battle Mountain, Nevada. Both of these latter plants are described in this volume. C. I. P. operations under construction at the time of this writing are as follows: Pinson Mining Co. , Nevada Gold Freeport Gold Company, Nevada Gold Compania Minera El Indio, Chile. Silver and Gold

Jan 1, 1981

By N. Morrison, E. J. Rogans, A. J. Macintosh, N. Schoeman

"The design of carbon-in-pulp (CIP), and carbon-in-leach (CIL) adsorption circuits has essentially remained unchanged since the early days of the carbon process for gold recovery. For CIP circuit the pulp residence time is traditionally fixed at one hour per contactor with a carbon concentration of between 15 and 20 grams per litre, and the counter current carbon transfer rates are in the region of 15% pulp recycle. For CIL, the pulp residence time is usually three hours per contact or, with lower carbon concentrations ( 5 to 10 grams per litre).The drawbacks of using the counter current CIP/CIL adsorption circuits are discussed using modeling developed for CIP/CIL plant design. Counter current CIP/CIL, circuits are then compared with the carousel method of adsorption circuit design.The use of equipment suitable for the carousel approach is discussed which is, the AAC cylindrical and pumping (MPS) screens, the AAC pump-cell plant and launder designs.Finally, two plants at the Vaal Reefs Gold Mining and Exploration Company that use carousel adsorption circuits, namely the Vaal Reefs No. 1 Gold Plant, a CIL plant with stepped contactors, and the Vaal Reefs No. 2 Gold Plant, a CIP using a very short residence time (AAC pump-cell) are discussed."

Jan 1, 1998

The carbon-in-pulp (CIP) process is now well established in the South African gold industry, with a total of over I million metric tons of material being treated each month in six large plants. This tonnage is derived from ground ore, from filtered pulp, from calcine, and from reclaimed sand-tailings dumps. With this new process and the new large plants, those concerned with CIP are experiencing a learning process, since each new plant presents a different set of problems to be overcome. The knowledge and experience gained from these plants is being shared, and will be of benefit in the design and operation of new plants. The CIP process can be subdivided into the following unit operations: prescreening at a fine size, adsorption, acid-washing and elution, reactivation, and electrowinning. Results concerning each of these unit operations, which were obtained from pilot plants and from large-scale CIP plants in South Africa, are presented. The latest developments in each of these areas is summarized. Tables that are included as an appendix contain some information concerning the equipment in these new CIP plants plus operating results from some plants.

Jan 1, 1982

By J. J. Komadina

Since the advent of resin-in-pulp (RIP) technology for treatment of uranium-bearing ores in the 1950?s to current carbon-in-pulp (CIP) processing of gold values, metallurgies and operators alike have wrestled with the problem of interstage screening. Early gold CIP plants such as at Homestake utilized externally mounted vibrating screens in conjunction with air lifts to effect carbon-pulp disengagement. Other operations world-wide have likewise adopted this technique with varying degrees of success. Subsequent development of in-tank launder screens both in South Africa and the United States have been of the air cleaned variety (EPAC)

Jan 1, 1988

What is the preferred electrolytic cell design and why? Hall: Considerable research remains to be done on electrolytic cell design. Studies are presently being conducted to determine optimum voltage and amperage. Zadra cells, which were used in some of the first carbon plants, are efficient when properly installed. Gold and silver are deposited on large-capacity, cylindrical steel wool cathodes. At times high value sludge falls from the cathode to the bottom of the cell. Rectangular cells, which were developed at some smaller operations in Nevada, require less floor space and have some desirable features in that cathodes can be moved and sludge can be removed from cell bottoms without actually shutting down the circuit. In South Africa two types of cells using graphite and diaphragm configurations are being tested. Duncan: The rectangular cell has one problem it's easy for shortcircuiting to occur. If you don't have a good seal on the side of the tank and on the bottom, the solution is going to want to flow around the bottom and sides of the cathodes and you're going to get poor performance in the cell. That is the advantage the Zadra cell has over the rectangular cell. With good sealing, which is a must, you should be able to get a ratio of the value of the solution going in to the value of the solution coming out of 10 to 1. Ken, can you tell me what you're attaining on the Zadra? Hall: At the Homestake gold operation in Lead, the cathode in the No. 1 electrowinning cell is loaded to about 600 ounces when it is moved to the refinery. At this time the No. 2 cathode is moved to the No. 1 cell. The No. 3 cathode is moved to the No. 2 cell and a cathode with new steel wool is placed in the No. 3 cell. In rectangular cells this sometimes is not possible because the loading on the cathode in the last cell may be as high as that in the No. 1 cell. As Don has pointed out this can probably be prevented by good seal design between cathodes. Potter: At the risk of sounding as though I'm straddling the fence, I really believe that either the round cell, as developed by Jack Zadra, or the rectangular cell will do an acceptable job. The Zadra is a fine unit. Leaks are not unknown but there are not very many. However, the rectangular cell is very saving of floor space. Plastics have been greatly improved during the past year or two and there is a very efficient design for the rectangular cell. It would have six cathodes in it and contain about 25 ft of steel wool. The body of this rectangular cell would be reinforced fiberglass plastic but with an integral lining of a high temperature plastic. I think either cell is so efficient and reliable that I would almost be tempted to flip a coin depending on floor space requirements. Either cell can be used to pull a loaded cathode and to advance the lesser loaded cathodes. Don, what is the configuration of your cell? Duncan: The Pinson rectangular cell has dimensions 2 ft wide, 30 in deep, and 10 ft long-long enough to take a dozen cathodes and anodes. We are currently using six of each but are not up to full capacity as yet. It's a steel tank coated with rubber. We have copper bus bars, which brings to mind that the last cathode in the tank, in one instance, was loaded heavier than the first one. That was probably a function of poor contact between cathodes and the bus bar. You can have erosion of the bus bar and if you don't get current flowing into the anode and out of the cathode, the cells will not function properly. Kappes: Just a few comments on cell design. In an alcohol stripping circuit we are running in Beatty„ NV, we are using PVC pipes for all circuitry piping and a commercial polypropylene electrolytic cell. They seem to be working quite nicely. The cell itself has eight cathodes measuring 18 in2. At six gallons per minute flow into the cell, at an average gold content of about 500 ppm, we seem to get good loading on the first three to four cathodes and not much on the end cathodes. At 12 gallons a minute flow we seem to be seeing gold uniformly along all eight cathodes. We are running at quite a high amperage level, about 400 amps into that cell. Gene McClelland, US Bureau of Mines, Reno Research Center (from the floor): I was associated with a company where the packing density of their steel wool cathodes was much too high and created some short-circuiting problems in their electrowinning circuit. I would like to ask the panel if they can recommend a packing density for cathodes in pounds of steel wool per cubic foot. Hall: The weight of steel wool put on one of our cathodes is 10 lb and the dimensions of the cathode are such that density would be about 0.75 lb/ft3. Duncan: I made a rough calculation and I'm estimating about 2 lb/ft3. Potter: In checking over a number of electrowinning operations, I found apparently very satisfactory operation within the limits that have been mentioned. I have come to a figure of about 0.5-1.0 lb of medium grade steel wool per cubic foot packed as uniformly as possible, of course. One consideration in packing is the fact that there should be good contact between the steel wool and the conductor. Operators tend to compact the steel wool more than would be desirable just to try to maintain good contact.

Jan 10, 1981

A panel discussion on carbon-in-pulp processing of gold and silver ores was one of the highlights of the 1981 AIME Annual Meeting in Chicago. The session generated considerable interest and discussion among panelists and the audience. For those unable to attend the panel, the program was recorded and the discussion appears in this two-part report. The panel was co-chaired by Robert S. Shoemaker, vice president of San Francisco Mining Associates, and Laurence D. Hartzog, principal engineer with Bechtel Civil and Minerals Inc., San Francisco, CA. Panel members included: George Potter, consultant, Tucson, AZ; Kenneth B. Hall, metallurgical superintendent, Homestake Mining Co., Lead, SD; and Donald M. Duncan, resident manager, Pinson Mining Co., Winnemucca, NV. There have been several types of carbon-in-pulp adsorption vessels in use, such as the Dorr-type agitator, the simple propeller agitated tank, the Pachuca tank, and, lately, the draft tube-type of agitated tank. Which one of these is best and why? Potter: On the selection of the most appropriate adsorption vessel, there is a considerable difference of opinion that stems largely from the fact that every ore is different. The mesh of grind, the pulp solids, and the apparent viscosity of the pulp as caused by its clay content and chemical conditions all differ. The traditional Dorr agitator with the slow speed center sweep and either peripheral or center column air lifts has worked quite well on the finer grinds of all minus 65 and probably 70-80% minus 200 mesh. Pachuca tanks have also been successful and they may be capable of handling a coarser feed than the traditional Dorr tank. One uranium mill, for example, handles minus 28 mesh sandstone ore in a Pachuca. The most recent development and one that commands consideration is the draft tube agitator in which there is a turbine which closely fits inside a draft tube. Velocity in the tube is carefully calculated to avoid undue shear and thus abrasion of the carbon. The objective in all cases, of course, is to mix the granular carbon, which is typically 6 x 16 mesh, very gently but thoroughly in a slurry with minimum carbon abrasion. I do not know that there is one outstanding choice just yet and I have been unable so far to get information on C-I-P service for ore grinds as coarse as 35 mesh. Duncan: The major advantage of draft tube-type is the ease of startup. At the Pinson plant we installed draft tube-type agitators but it is too early to quote experience with them. We also haven't operated long enough to determine just what our carbon loss is. The advantage, of course, in the draft tube design is that it requires only about one-third the horsepower input of a conventional agitator. If it has no other advantages, it has that. Hall: The type of vessel most suitable for C-I-P adsorption depends on the type of ore treated and the prevailing operating conditions. In most cases, a deep tank with turbine-type mechanical agitator and low speed tip velocities would be satisfactory. Turbine-type impellers give a positive type of agitation which assures optimum ion contact and reduces short circuiting. Thorough aeration is possible with an air sparge properly located. A mechanical agitator can easily be started up after an outage, but it is usually necessary to drain and wash out a Dorr rake-type or Pachuca before restarting. The turbine-type impeller requires more power, but maintenance costs are negligible if rubber covered impellers are used. Carbon losses are minimal. In smaller plants, Pachuca type agitators provide adequate aeration and agitation. Bob Polak, Occidental Minerals (from the floor): Mr. Hall, you favor the mechanical-type agitator with the preface that the proper design is critical. Could you elaborate on this for us? Hall: The most important thing is low tip speed to prevent carbon attrition. I think the impeller should be sized so that you get a good sweeping action toward the bottom of the tank, across its bottom, up the sides, and back to the center. The advantage of the draft tube is that you get a more positive agitation and you probably get improved aeration too. Polak: Do you know of anyone using an upflow mechanical agitator rather than a downflow unit? Hall: I think that Bob Wilson at Custom Equipment has designed one where he has located the sparge directly beneath the impeller. The air bubbles are broken up by the impeller as the slurry passes through it. The slurry flows upward, outward, down the sides, and, again, back to the center of the tank. I don't know that any tanks of this design are in commercial use. Hans Von Michaelis, Randol International (from the floor): A question to any of the panelists on flat bottom versus conical bottom Pachucas. Hall: I would say the conical bottom would be most suitable in most cases. Some plants have experienced problems with flat bottom Pachucas in that they have a tendency to sand in on the sides of the tank so only the center of the tank is active. Duncan: With our draft tube tank we placed an inverted cone in the center of the tank bottom and blanked off the bottom comer around the circumference of the tank to facilitate movement of the pulp. Other than that, as far as conical bottom tanks are concerned, I'm generally opposed to them because of the cost and height differential. Larry Kramer, Kennecott Minerals Co. (from the floor): Mr. Duncan, you mentioned that the draft tube-type could be agitated with about one-third the horse-power applied to a conventional propellor agitated tank. I have trouble trying to pin down that kind of number. Could you give a bit of rationale as to why that mechanism has a lower horsepower requirement? Duncan: I think it has to do with the fact that below the propeller you have straightening vanes. The pulp, which is flowing vertically downward, is turned and flows upward again without any recirculation. You have an inherently less horse-power requirement in that type of tank. The one-third horsepower requirement is a number I obtained from Lightnin, which supplied us with details of the draft tube. There is probably much more recirculation with a conventional impeller type that is wasted motion. Potter: Last week I saw some agitators in South Africa with short draft tubes and actual turbine-type impellers. This plant was handling 200 kt of ore per month. The tanks were flat bottomed, and the agitation appeared to be quite satisfactory.

Jan 8, 1981

By F. -Z. Ji, G. A. Irons, M. Barati, K. Coley

The use of oxygen in electric arc furnace steelmaking is tied to the use of fossil fuels, and slag foaming. The current work examines the kinetics of carbon injection into EAF slags especially the saturation injection rate and available reaction area in the slag foam. Based on individual rate data and experimental gasification rates of carbon in the slags, the available reaction surface area in the gas bubbles was found to be around 1900¬4700 cm2.kg-slg-1 for carbon injection into EAF like slags at appropriate injection rates and steel making temperatures. The ratio of number of bubbles to number of particles is 1 to 17 and the weights of carbon per unit reaction area are 0.001-0.008 gC-cm-2. Using the relationship between active reaction area and x supplied in this study, the gasification rates of carbon in slags can be estimated with gas-slag interfacial reaction rates.

Jan 1, 2004

By Jilai Xue

Industrial wastes containing 30-50 wt.% Al2O3 and 40-60 wt.% SiO2 may serve as an alternative resource for producing Al-Si alloys. Various raw materials such as used refractory materials from metallurgical furnaces, coal fly ash, andalusite residues, and so on were tested in laboratory to produce Al-Si alloys using carbon-thermal reduction process. A mixture of anthracite and petroleum coke was used as reducing agent. One of the most important operations was to prepare the briquettes made of different raw materials with varying contents of Al2O3 and SiO2. The effects of briquette property, A/S ratio (mass ratio of Al2O3 and SiO2), the amount of carbon reducing agent, on the reduction process and the resulting metals were investigated. The results are useful for development of an alternative technology for Al-Si alloy production, which has the potential application in recycling metals from industrial wastes containing Al2O3 and SiO2.

Jan 1, 2010

By G. Voiloshnikov, A. Bogudlova

"The deleterious effect of carbonaceous matter during cyanidation of gold ores (so called preg-robbing) has been recognized for many years. Based on this, a new method using flotation to reduce the content of carbonaceous matter was developed. Low-sulfide gold-bearing ore with carbonaceous matter of 0.14% from a Russian deposit was processed. The purpose of these tests was to compare two flow sheet options. Option I comprised removal of carbonaceous product prior to sulfide flotation. Option II comprised removal of carbonaceous matter from flotation concentrate. It was found that the content of carbonaceous material can be reduced in sulfide gold-bearing concentrate prior to leaching. High gold recovery was observed during the separation of carbonaceous material prior to sulfide flotation using Option I. Due to lower reagent consumption the costs for reagents were decreased using Option II. The results have shown the effectiveness of a new method. Patent No. 2783808 was obtained for removal of carbonaceous material prior to sulfide flotation. This information will be used to design a large processing plant flow sheet in Russia."

Jan 1, 2014

By M Barley, C A. RosiFre, L Lobato

The Carajßs iron ore deposits contain approximately 17.5 billion tons of ore with >64 per cent Fe and occur in the eastern part of the Amazonas Craton. They are hosted by jaspilitic banded iron-formation (BIF) of the Carajßs Formation which, together with metavolcanic rocks, comprise the ~2.75Ga Grpo Parß Group of the Itacai·nas Supergroup in the ~1000 km long, E-W trending Carajßs Synclinorium. The Carajas Formation comprises discontinuous layers and lenses of partly dolomitised BIF (17 - 43 per cent Fe and 35 - 61 per cent SiO2) and lenses of high-grade iron ore, cut by mafic sills and dykes. The high-grade iron ores occur as large tabular bodies of friable (soft) hematite with smaller lenses of hard (compact) hematite. The hard hematite ores typically occur at the contact with the underlying volcanic rocks and are surrounded by an aureole of hydrothermal carbonate alteration. BIF that has been overprinted by dolomite and magnetite crystallisation has recently been discovered at depth in the N4E Mine. With increasing amounts of carbonate, the original lamination (microbanding) and other fine primary structures in the BIF have been progressively obliterated resulting in alternating carbonate and iron oxide mesobands. The friable hematite ore that is characteristic of the Carajßs deposits results from ongoing weathering and leaching of the carbonates from this type of altered BIF. The hard hematite ores probably result from more extensive early oxidation. The association of both carbonate-altered and jaspilitic BIF with the N4 Mine is similar to that observed at the Mount Tom Price deposit in Western Australia, where carbonate-altered BIF occurs below massive hematite ore with a jaspilitic halo developed above the orebody. This indicates that as at Mount Tom Price, hydrothermal carbonate alteration and associated loss of silica from BIF may be an important step in the formation of these giant hematite deposits.

Jan 1, 2002

By G R. Dickens, N H. S Oliver

The genesis of giant hematite ore deposits in northwest Australia remains a contentious topic in part because key evidence supporting a unifying genetic model has not been found at all deposits. In particular, several papers have proposed that carbonate replacement of silica layers in banded iron formation (BIF) by basinal brines is a requisite first step toward ore formation. This initial hypogene stage is inferred primarily from the presence of silica-poor, carbonate-rich rocks found below ore and along normal faults at the Mount Tom Price and Giles Mini deposits. However, until recently such rocks have not been identified at the largest martite-microplaty hematite deposit, Mount Whaleback. In this study, samples of the upper Mount McRae Shale are examined for their chemistry, mineralogy and petrography. These samples were collected from several key locations, including within drill core that penetrates an area immediately beneath ore along the Mount Whaleback fault at Mount Whaleback. Compared to unaltered black shale from Wittenoom Gorge in the north and altered black and red shale at Mount Whaleback, reddish-green shale below the Mount Whaleback deposit is significantly enriched in MgO and CaO and depleted in SiO2. Samples of this shale consist predominantly of fine- to medium-grained dolomite and ankerite cut by chlorite and carbonate veins, contrasting with unaltered equivalents that contain mostly stilpnomelane, K-feldspar and relatively minor carbonates. This alteration is distinct from assemblages developed during regional metamorphism, and possibly represents hydrothermal alteration after metamorphism. Although several questions remain unanswered, these results support models that invoke an early hypogene stage during the formation of the martite-microplaty hematite deposits in the Hamersley Province.

Jan 1, 2005

By Peter Bush

The deposition of metastable carbonate minerals in ar. aid, sheltered, coastal environment, leads to the formation of a flat, coastel, sabkha plain. The ground waters of the sabkha plain are modified by evaporation, precipitation of salts and reaction between ions in solution and the host carbonates. The resulting brine is similar to those found in fluid inclusions associated with Mississippi Valley type deposits. The aragonite and high magnesium calcite found in the sediments can concentrate lead and zinc from sea water. On diagenesis the lead and zinc are released into the sabkha brines.

Jan 1, 1979

By X Liu

The crystal chemistry of carbonate in Ca apatites, including Na-free and Na-bearing hydroxylapatite (CHAP) and Na-bearing fluorapatite (CFAP) and chlorapatite (CCLAP), has been investigated by Fourier transform infrared (FTIR) spectroscopy and single-crystal X-ray structure, using crystals synthesised from carbonate-rich melts at 1 GPa, 1400 - 1000¦C. The carbonate ion substitutes for both the X (OH, F, Cl) anion species in the apatite channel (type A carbonate) and the phosphate group (type B carbonate). The type A carbonate ion is oriented in the channel with two oxygen atoms close to the c-axis, and the type B carbonate ion is located close to the sloping faces of the substituted phosphate tetrahedron, with details varying with composition series. Sodium promotes the uptake of type B carbonate and also has a profound effect on FTIR spectra. Crystal compositions correspond approximately to the substitution formula Ca10-(y+z)Nay z[(PO4)6-(y+2z)(CO3)y+2z][X2-2x(CO3)x], with x + y up to 1.0 and z + 0.0 for CHAP, x + y + 4z + 0.4 for CCLAP, and x + y + 2z + 0.1 for CFAP, for equivalent conditions of synthesis. The sodium cation and A and B carbonate ion defects are locally coupled in all three composition series to facilitate charge compensation and minimise the effects of spatial accommodation. Synthetic Na-bearing type A-B CHAP with x + y + 0.5 has a similar chemical composition and FTIR spectrum to biological apatite.

Jan 1, 2008

By G. Robert Ganis

The folded Appalachians are a physiographic province of eastern North America extending from Nova Scotia to Alabama. The province strikes through the state of Pennsylvania (see Fig. 1) comprising roughly 20 percent of the state and it is here that the focus of this paper will attend. The province is a thick sedimentary sequence which was compressed into a folded mountain belt by the Appalachian Orogeny which terminated at the end of the Permian. The stratigraphy contains both carbonate and non-carbonate rocks as a reflection of the depositional environment at any specific time and place during the Paleozoic geosynclinal accumulation. Although a great deal of variety and difference exists in the geology from one end to another, a common thread of structural and stratigraphic style exists. Carbonate rocks, limestones and dolomites, comprise a substantial percentage of the total Appalachian stratigraphy and are interbedded with clastic materials such as sandstones, siltstones, and shales. The carbonate rocks are extensively mined and collectively represent a vast economic resource.

Jan 1, 1983

By N. A. Abdel-Khalek

The amenability of carbonate separation from a sedimentary phosphate ore using a bioflotation process was studied. Two types of bacteria were chosen for this study. The experiments were performed using oleic acid as collector. The flotation experiments were carried out using statistical designs for optimizing the main operating parameters. A concentrate containing 0.78% MgO and 30.15% P2O5 with a recovery of 92.31% was obtained from a feed containing about 2.45% MgO and 27% P2O5. These specifications could not be obtained using conventional flotation experiments under similar conditions in the absence of bacteria. Measurements of zeta potential, adsorption of bacteria and collector, as well as froth power, were performed to explain the role of microorganisms in the surface modification of both dolomite and phosphate and in their interaction with the collector.

Jan 1, 2009

By S. R. Titley

Carbonate-hosted massive sulfide (60%) ores of the western Cordillera compose a distinct class of deposits although they vary widely in detail and perhaps genesis. They have been important sources of lead, zinc, copper, silver, gold, and more rarely, molybdenum, tin, and tungsten in complex mineral assemblages usually dominated by pyrite. They occur as concordant stratiform bodies, as discordant mantos, and as chimneys crossing tens of meters of section; many are associated with faults and breccia bodies. Environments of formation of carbonate hosts range from craton basin to shelf with ages from Proterozoic to Cretaceous; in many instances, dating has shown mineralization to be significantly younger than hosts. Temperatures of formation determined for many deposits are high (200°-400°) and many districts are centers of igneous activity manifested by dikes, sills, and stocks. However, direct cause and effect relationships have been difficult to establish. Many important problems attend the renewed interest and study of these deposits and include questions of metal-sulfur sources, metallization processes and histories, geological controls at all scales, and relationships to broader patterns of metallogeny.

Jan 1, 1985

By Peter Megaw

The paper point out that the carbonate Carbonate Replacement Deposits (CRDs) are epigenetic, intrusion-related, high-temperature sulfide-dominant Pb-Zn-Ag-Cu-Au-rich deposits that typically form lenses or elongate to elongate-tabular bodies referred to as mantos or chimneys. Recent studies have shown that CRDs do occur in predictable geologic environments, allowing focusing of regional exploration. In addition, they have mappable alteration patterns that can be used to determine the magnitude of a given system and elemental zoning patterns that greatly enhance the chances of drilling success. Several recent discoveries of “blind” replacement deposits have been made by careful field evaluation of host and capping rocks coupled with geophysics.

Apr 24, 2001