Search Documents

By Aurel Goodwin, Diann Kraft, V. S. Znamensky

This chapter deals with the Mine Safety and Health Administrations's (MSHA] concern and obligations with regard to asbestiform minerals. Asbestiform minerals are defined as the magical group of hydrated, silicate minerals that possess a fiberlike structure capable of being woven into cloth. Their unique combination of properties, such as resistance to heat and chemical attack, high tensile strength, and flexibility was recognized centuries before Christ. Pausanias, the early Greek geographer, speaks of golden lamps, made about 430 BC, with in- combustible wicks of Carpathian flax. The Ro- mans used asbestos as cremation clothes to con- serve the ashes of deceased persons of rank. Charlemagne had an asbestos table cloth that he used to pass through fire to clean (Lanza, 19381. Early recognition of the health hazards associated with exposure to asbestos was documented in the first century by Pliny the Elder, a Roman naturalist, and Strabo, a Greek geographer. Both wrote of slaves with sickness of the lungs, whose occupation was that of weaving asbestos into cloth. This concern for the health of asbestos workers disappeared over the ages. Today, with the use of modern technology, asbestos products have been greatly exploited. The asbestos output has increased over a hundredfold in the past 70 years. World production has jumped from 454 t/y (500 stpy) in 1900 to 4.5 Mt/y (5 million stpy) in 1978. An increase in health problems for asbestos workers accompanied this increased usage. However, it was not until the modern era that the association of asbestos with chronic respiratory disease was rediscovered. Reports were published at the turn of the century documenting the effects of asbestos exposure on textile workers. One such report in 1907 by H.M. Montague Murray described the post mortem findings on a 34-year- old carding machine operator. Murray de- scribed the lungs as showing extensive diffuse pulmonary fibrosis spicules of asbestos. Subsequently, more reports of pulmonary fibrosis following inhalation of asbestos were published, including an epidemiological study of asbestos miners in 1930 (Merewether and Price, 1930), at Thetford, Que., Canada. This study took place at the mine 52 years after large-scale mining of asbestos had begun. But, the cancer- producing potential of asbestos was not established until 1949 when a report by Merewether in England described an excess of cancer of the lung and pleura [the lining of the lungs) among individuals dying from asbestosis (Merewether, 1949). In the past decade much attention has been focused on asbestosis, mesothelioma, and bronchogenic carcinoma, as the three major biological effects associated with asbestos ex- posure. Parenchymal and pleural asbestosis is a fibrosis in the substance of the lung with thickening and often calcification of the membranes lining the thoracic cavity. Mesothelioma is a malignant tumor of the membranes lining the thoracic or abdominal cavities, and bronchogenic carcinoma is a cancer of the lung tissue itself. These diseases occur in various degrees and combinations. The severity and occurrence of these biological effects are directly influenced by conditions such as dose response relationships, intensity of exposure, duration of exposure, lapse of time since initial exposure, and cigarette smoking. Numerous studies indicate that the relationship between these conditions and the incidence of disease is proportional. Congress has recently concluded (Congressional Record, 1979) that, "exposure to asbestos fibers has been identified as significantly in- creasing the incidence of cancer and other severe or fatal diseases such as abestosis." Congress conveys its concerns for the safety and health of the nation's miners through the Federal Mine Safety and Health Act of 1977 in which it gave MSHA the authority to set safe

Jan 1, 1986

By George H. Roseveare

Early flotation dealt primarily with the bulk concentration of sulphide minerals or the separation of one sulphide from another and was referred to as oil flotation because oils and fats were used as reagents. The separation or concentration of one nonmetallic mineral from another developed later with the use of fatty acids. Fatty acids are organic acids present usually as glycerides in tall oil and oils of fish, peanut, cottenseed, soya beans and ethers of veg¬etable and animal origin. Some, of these oils and their derivatives were used by the Phoenicians as early as 600 B.C. in making soap, and the use of such reagents in mineral dressing is referred to as "soap flotation". The first use of oleic acid for the recovery of minerals was the early agglomeration process.' The coarse particles of ore, from 1/16 to 1/4 inch diameter, were coated with large amounts of soap or oil and after screaming from the gangue were recovered by screening, hydraulic or table classification. In 1886, a patent was issued to Mrs. Carrie Everson in which the essential feature was the constituted commingling of pulverized ore, fat or an oil, either animal, mineral, or vegetable, for the purpose of effecting .a. union of the free metal or metallic portion of the ore with such admixed material whereby the same may be changed in subsequent separation of quartz or other rock therefrom by washing or other suitable means. The patent mentions the use of red, cotton seed, caster, sperm and linseed oils, In the early use of collectors the amount of oil for froth flotation was often 2 to 6 per cent by weight of the ore rather than pounds per ton.

Jan 1, 1959

By P. W. Conrad, C. Todd, N. West, R. Kramer

"Surface subsidence caused by both underground room-and-pillar mining operations and solution mining operations have each been studied separately, but never combined. In 2008, FMC Minerals began using solution mining at its Westvaco Mine as a secondary extraction method in an area that had been previously mined using the room-and-pillar mining method. Mining regulations require that subsidence associated with underground mining activities be monitored and measured annually. Researchers at Montana Tech were able to develop a relationship between measured surface mine subsidence and solution mining that can be used at the Westvaco Mine to estimate the production of trona from solution mining operations. PROJECT BACKGROUND FMC Minerals (FMC) has increased the production of trona from its Westvaco Mine near Green River, Wyoming, using solution mining as a secondary extraction method in an area previously mined using the room-and-pillar method. The area of interest was mined until 2001 with the use of a borer miner at a depth of approximately 1,600 feet. Currently, FMC determines the amount of trona produced using its solution mining operations by measuring the dissolved solids pumped from the mine. This approach, however, does not account for the location from which the trona was removed. The location from which the trona was removed and the size of the cavern created by the solution mining operations is important to FMC’s mine planning. FMC believed that with proper investigation of the subsidence at the Westvaco test site, a correlation might be found that would allow for the use of surface subsidence measurements to estimate the amount and location of trona production from the solution mining activities. The primary goal of this project, conducted by Montana Tech, was to find a relationship between the measured subsidence and the solution mining activities. The project attempted to model the relationship between the measured subsidence and the solution cavern using Salt_Subsid, an existing subsidence software package from the Solution Mining Research Institute (SMRI), to determine the program’s usefulness for locating and developing the cavern created by solution mining activities. The project also attempted to develop an equation that could be used to predict solution trona production based on measured subsidence. The data used in this study were collected over a seven year period, 2008 through 2014."

Jan 1, 2016

By S. F. Diehl

Suites of monomineralic sulfide and carbonate minerals, as well as mine-waste composite samples, were analyzed using chemical and microanalytical techniques to understand behavior and bioavailability of mine waste elements such as Cu, Fe, Pb, or Zn. Petrographic, scanning electron microscopy (SEM), and laser-ablation inductively-coupled mass spectrometry (LA-ICP-MS) studies of mineralogical residence sites of trace elements are important because trace elements affect the chemical and physical behavior of minerals. Leachate solutions show that chalcopyrite, bornite, azurite, malachite, and galena are host to the trace elements Ag, Al, As, Cd, Co, Cr, Mn, Ni, Pb, and Zn. SEM studies reveal whether these trace elements occur within mineral inclusions or are substituted within lattice structures. SEM analysis reveals mineral phases not identified by X-ray diffraction (XRD), such as inclusions of sphalerite and cobaltite(?) within chalcopyrite.

Jan 1, 2010

By John M. Smith

Kaolin is an important industrial mineral because of its unique properties and low cost. Strictly defined, kaolin is the name given to a group of hydrous aluminum silicates of which kaolinite is the most common mineral (1). Through common usage the mineral, kaolinite, is called "kaolin" or "china clay". In 1972 over 4, 000, 000 tons of kaolin will be beneficiated and shipped by domestic producers. By far the largest user of kaolin is the paper industry which utilizes approximately 65 to 70 per cent of the total production. Kaolin is used in paper as a filler in the interstices of the sheet and as a coating to impart smoothness, gloss, brightness, and printability to the paper. The rubber industry is also a large user of kaolin where it is used as a filler because it adds strength, abrasion resistance, and rigidity to both natural and synthetic rubber goods. Kaolin is used as an extender in paints because it is chemically inert, has a high covering power, gives desirable flow properties, and is low in cost. In ceramics, kaolin is used in whitewares, tile, insulators, refractories, and in some face brick where a white color is desired. Kaolin is also used extensively in plastics as a filler in thermosetting and thermoplastic mixes to give smoother surfaces, a more attractive finish, good dimensional stability, and resistance to chemical attack. Many other process industries use kaolin as a filler, suspending medium, or for color improvement.

Jan 1, 1972

By Zachary E. Wedding, Zach Agioutantis

Excavation of underground openings results in the redistribution of the in situ stress into the rock adjacent to the opening. Stress redistribution depends on opening geometry, pillar geometry, material properties, possible confinement, and constitutive models describing the behavior of adjacent rock. This paper presents typical pillar stress distributions for elastic and yielding pillars as a function of opening geometry, material properties, and material constitutive models and highlights the differences between them. Stress distributions are compared with empirical strength profiles that have been developed for coal pillars as well as actual pillar geometries documented for stone pillars.

Jul 1, 2023

By L. Alagha, F. Schott, M. B. Haya, Z. Xiao, K. C. Monyake

"Froth flotation is a process in which valuable minerals are separated from gangue minerals on the basis of surface wettabilities. It is a universally accepted process for the beneficiation of coal. The large amount of coal fines that have been generated from both mining and beneficiation processes has been reported as a chronic problem to both fine coal preparation and utilization as these fines contain a high amount of ash forming minerals. The current study investigated the potential application of Synthetic Bio-compatible Polymers as slime depressants in fine coal flotation for the possibility to enhance the combustible recovery and ash rejection. Raw coal samples containing 21% of ash-forming minerals were crushed, grinded and floated in the presence of Chitosan polymer. Flotation tests were carried out in D-12 Denver flotation cell with 1-Liter capacity. Flotation outcomes were studied as a function of polymer concentration. Box-Behnken factorial method was used for experimental design. Second order response functions were produced for ash% and combustible recovery. The results obtained from this study demonstrated positive influence of chitosan polymer on ash% and combustible recovery. Ash % was decreased by 3.32 % while an increase of 48.15 % in combustible recovery was observed when chitosan was introduced in the flotation process. INTRODUCTION Froth flotation is a widely used method of separating minerals by utilizing the difference between surface wettabilities [1], [2].Modern mechanized mining and ore handling operations produce large amounts of coal fines which in the past were not processed but discarded as waste[3]. Even though flotation is the best method of beneficiation for coal, it can be challenging in case of fine coals. In fine coals, slime coatings of colloidal mineral matter exist on the coal surface. These coatings render the coal hydrophilic, hence reducing flotation efficiency and recovery. Of late, different researches have been using biodegradable polymers to determine their feasibility in enhancing fine coal flotation efficiency[4].Naturally occurring and synthetic polymers, for example, polyacrylamide-based polymers, have been widely used in flotation as multifunctional reagents[5],[6],[7]. Hybrid polyacrylamide polymer has been successfully used as a depressant for ash forming minerals in fine coal flotation[3]. Recently, chitosan has been successfully used in flocculating quartz particles to produce faster settling rates of fine tailings [4]."

Jan 1, 2018

By Campbell J. McKenzie

Following on from the successful completion of three exploration programs and the discovery of two new inactive Seafloor Massive Sulphide (SMS) deposits within New Zealand?s Exclusive Economic Zone (EEZ), Neptune is now poised to take the next step from explorer to developer. Neptune considers that commercialization of SMS deposits represents the future of the mining industry, providing a new source of metals to the world economy, and enabling host countries to benefit from this new industry. Neptune recognizes that marine biodiversity is among the greatest treasures of New Zealand. The geological isolation, range and complexity of habitats, and a number of major ocean currents that influence New Zealand have created diverse marine communities. Neptune, recognizing both the environmental importance of marine biodiversity and the value it provides to all New Zealanders has made commitments to ensure sustainable development. There are many unanswered questions regarding how the marine environment may be affected by SMS development, however best practice environmental management is a key aspect of the Company?s approach to our activities and the code for ?Environmental Management of Marine Mining? prepared by the IMMS has played a part in this approach. Neptune has close relationships with the scientific community to ensure that appropriate environmental strategies and plans are developed in order to minimize the effects of our activities on the environment.

Jan 1, 2008

By H. Y. Yang, L. L. Tong

Semicontinuous-flow, multistage biooxidation experiments of a Chinese refractory, high-sulfur gold concentrate were conducted with different pulp densities for gold recovery. The maximum iron, sulfur and arsenic oxidation rates of 90.0, 88.8 and 96.4 percent, respectively, were obtained in the experiments with 5 percent pulp density. The highest gold and silver recoveries of 96.1 and 68.9 percent, respectively, were achieved by cyanidation. The negative effect of high pulp density on biooxidation was related to the decrease of free and adsorbed cell concentrations with increasing pulp density. The data of iron oxidation from the semicontinuous biooxidation experiments were best fitted by a shrinking core model in which the chemical reaction controlled the rate. The dissolution kinetics of sulfur and arsenic were therefore analyzed by a shrinking core model in which the internal diffusion controlled the bioleaching rates. For the quantitative description of biooxidation efficiency, two parameters — mass dissolution rate and volume dissolution rate — were proposed. In the first stage, the mass dissolution rates of minerals were negatively correlated while the volume dissolution rates were positively correlated with the actual pulp density. The iron and sulfur mass dissolution rates decreased with increasing actual pulp densities in the third and fourth stage, while linear increasing relationships between the volume dissolution rates of minerals and the actual pulp density were observed from the second to fourth stage. The highest mass dissolution rates of minerals were obtained in the first stage with 5 percent pulp density. The highest volume dissolution rates of minerals were obtained in the first stage with 15 percent pulp density. Compared to the volume dissolution rate, the mass dissolution rate was more intuitive to reflect the negative effect of high pulp density on biooxidation efficiency.

By J. D. Vincent

The Henderson mine site is located at Red Mountain on the eastern slope of the Rocky Mountains, approximately 50 miles west of Denver, Colorado. The mill site is on the west slope of the Rockies and mine and mill will be connected by an underground railroad. All designs were for a 30,000 ton per day molybdenite processing plant with provisions for future expansion up to 50,000 ton per day if required. This plan did not just happen, but slowly evolved over the course of about three and one-half years. Many plants cannot afford such a delay, but the Henderson project will take about 10 years from the time it was first discovered until production starts, and these 3 !1 years were well spent in determining the best possible plant site and flowsheet. This paper describes some of the problems and the decisions made in arriving at the final location and flowsheet. The paper does not go into the specific details of how protection of the environment went hand-in-hand with all other project considerations. This particular aspect of the planning has been well-reported on other occasions and considerable information on it is readily available.

Jan 1, 1972

By Karoly C. Kocsis, Kyle A. Scalise, Marcelo Bandeira Teixeira

Understanding the effects of various ventilation and climatic parameters on the work conditions and comfort in underground mines is critical for efficient ventilation system design and cost savings and to ensure the health and safety of mine workers. To understand the effects that the thermal damping effect (TDE) and the thermal flywheel effect (TFE) have on the ventilation system design and potential cooling system, this paper compares and analyzes the wet and dry-bulb temperatures at the bottom of an intake shaft using two modeling software packages, Ventsim™ and Climsim™. The comparison shows the consequences and importance of taking into account the TDE/TFE when predicting the climatic conditions in future underground mines, especially when deciding on whether a cooling system should be employed in order to provide adequate climatic conditions in the production stopes, dead-end development headings, and throughout the mine. Ventsim™is able to account for the TFE, while Climsim™does not. Both software packages have their uses and are used within the mining industry, but it is useful to understand their limitations and where the future of underground climatic modeling will lead.

Oct 9, 2020

By X. Y. Yu, X. A. Wei, A. Zeng

"The flotation behaviors of diaspore and three kinds of silicate minerals - kaolinite, illite and pyrophyllite - using an organosilicon cationic surfactant as collector were investigated as functions of reagent concentration and pulp pH. The results show that the organosilicon cationic collector QAS122 is a suitable collector for the flotation of aluminosilicate minerals but has weak collecting ability with regard to diaspore, enabling the flotation separation of diaspore from silicate minerals using QAS122 as collector. The flotation of a bauxite ore was then studied in detail. Finally, a reverse flotation separation process was used to process a low-grade bauxite ore. It was concluded that use of the organosilicon cationic collector is effective. A concentrate with aluminum oxide (Al2O3) to silicon dioxide (SiO2) mass ratio, or A/S, of 9.67 was obtained from natural bauxite ore with A/S of 6.07 at pH of around 11. The Al2O3 recovery rate was 81.72 percent. IntroductionChina has abundant bauxite ore resources, but more than 98 percent of the bauxite ores are the diasporic type, with the characteristics of complex mineral composition, low aluminum oxide (Al2O3) to silicon dioxide (SiO2) mass ratio, or A/S, and difficulty of processing. The gangue minerals in bauxite ores are mainly kaolinite, pyrophyllite and illite, containing titanium and iron impurities (Zong et al., 2008). It is known that high-grade bauxite ore, with A/S greater than 8, can be processed directly by the Bayer process (Papanastassiou et al., 2002; Ma et al., 1996). However, Chinese diasporic ores have been processed mainly by the sintering process, which is environmentally damaging and energy intensive. Increasing the A/S of the diasporic ores using a flotation method is needed (Xia et al., 2010).Froth flotation is one of the most widely used processes to concentrate valuable minerals in beneficiation ores. It is particularly useful for separating finely ground ores from their associated gangue minerals. For diasporic bauxite ores, flotation is applied to obtain high-quality material for the Bayer process by increasing the A/S. Direct flotation has been shown to be an efficient method for the desilicating of diasporic bauxite ore (Wang et al., 2004; Xu et al., 2004), but reverse flotation has more advantages for this purpose, including less collector consumption, less foaming product and less effect on metallurgy (Liu et al., 2007; Hu et al., 2003; Hu, 2003; Luo et al., 2001)."

Jan 1, 2015

By Nicholas Tabor, Norbert Fuegenschuh, Richard Taylor, Jean-Marc Wehrli

The Plymouth Tunnel forms part of the 16-mile long route of the Purple Line Light Rail Project promoted by the Maryland Transit Administration. The tunnel is approximately 1,220 feet in length with a shallow vertical alignment located beneath a residential area. Challenging mixed ground conditions included surficial soils, decomposed Saprolite, and highly weathered to fresh rock requiring the use of the Sequential Excavation Method (SEM) for construction. This paper discusses innovative approaches implemented during construction as well as challenges faced during planning and installation of a spray-applied permanent concrete liner.

Jun 13, 2021

By Mustafa Akser

The Pipestone Lake anorthosite complex in Manitoba, Canada, was recently been re-identified as a potential source for titanium, iron, and vanadium. The present study utilized a 350 kg hard rock sample, which originated from the "Main Central" zone of the deposit. Commercial pilot-size equipment, such as dry low intensity roll magnets, wet high intensity magnets (WHIMS), and high tension electro-dynamic roll separators, was employed. As products, ilmenite up to 48.5% TiO2, and magnetite concentrates up to 87.9% Fe3O4 with 5.25% TiO2 were obtained. The majority of the vanadium reported to the magnetite concentrate. Subsequent characterization of various separation products shed light on the potential grade and recovery of the minerals from this deposit.

Jan 1, 1996

By David Green

Outokumpu introduced Flash Flotation in the early l 980's for the recovery of floatable material from grinding circuits. The devel­opment came as a result of surveys made in the company's own concentrators, initiated to find ways of improving recoveries with increasingly complex and lower grade feeds. Hydrocyclones make a separation on the basis of particle size and mass, resulting in the "over collection" of fine grained, high S.G. particles. Minerals such as pentlandite, galena and gold are easily caught in the circulating load around the mill until they are overground and rendered more difficult to collect. In the case of downstream flotation this may simply involve a reduction in the rate coefficient due to the finer sizes or, as is commonly experienced in gold operations, the mate­rial is slimed and coated onto non-floating gangue and is eventual­ly lost to tails. At the time of Outokumpu's plant surveys, it was a relatively common practice, particularly in Pb operations, to have a flotation section fed directly from the secondaiy mill discharge. This is called unit flotation and certainly provided an improvement but very high wear rates and frequent sanding out of the cells was com­mon. The development of the SkimAir® Flash Flotation cell by Outokumpu provided a subtle but quite dramatic departure from the unit cell approach. Now it was possible to feed cyclone under­flow into a special purpose-built flotation machine and recover a final grade concentrate from the grinding circuit (see Figure I). The cell was designed to handle the coarse circulating load, per­mitting the coarsest fractions to be short-circuited back to the mill and retain the floatable sizes for a nominal time of 30 seconds to several minutes. The short retention time was possible largely due to the relatively clean content of the cyclone underflow stream. This means that the fine gangue is not present except in small quan­tities and most of the fine to mid-size paiiicles are higher S.G. and more likely represent valuable mineral. This condition provides for very high rate coefficients. Typical operations would recover 40-60% of the valuable mineral in this fashion and improvements in recovery were typically from 2-5% for sulphide minerals to the 5-20% range for gold and silver.

Jan 1, 1998

By F. L. Wilke, J. Fabian, D. Oravec

The task of production planning in ore mining is primarily con¬cerned with the removal of ore blocks within planning periods spread over the life of the mining operation. The investigation of this problem in the past resulted in the introduction of computer based optimizing techniques for production scheduling and se¬quencing. Although these techniques succeed in computing an "optimal" mine output for one planning period, they usually fail in composing a practical and feasible mine plan over the periods in concern. This paper describes conventional production planning based on operations research and the capabilities of a knowledge-based approach. An example of a planning system for the Slovak under¬ground iron ore mine Nizna Slana will be presented. By combina¬tion of these two techniques this system should improve the qual¬ity of planning procedures.

Jan 1, 1996

By I. Longson

As a longwall coalface advances a caved goaf or waste region is left behind. Air flow takes place through this permeable goaf due to the pressure differentials existing across it and en route this leakage air picks up both heat and moisture. A marked deterioration in climatic conditions occurs in the face area at all points downstream of where this leakage air rejoins the main air-stream. This goaf heat source can make a very significant contribution, typically 30-40% to the rate of total heat pickup on an advancing UK longwall coalface with a VST of 40°C and hence on the climatic conditions that prevail at the return end and in the return gate of the face. The magnitude of the rate of heat collection from the goaf depends on a number of factors but it has been established that it is particularly influenced by the prevailing virgin rock temperature and the total flow rate of the leakage air. This paper proposes a model for the goaf based on a packed bed analogy and other assumptions required in order to evaluate the rate of heat pickup are identified. The outlet condition of the leakage air predicted by the model have been shown to correlate with underground measurements taken for a range of different production patterns with the face cutter at various locations on the face. The sensitivity of these predictions to variations in the input data has been tested and is commented on. At this stage of the development the capabilities and predictive limitations of the model are discussed. Further areas of investigation are suggested in order to improve the predictive ability and to extend the versatility of the model.

Jan 1, 1989

By G. R. Giuliani

Hanna Mining Company's Groveland Mine is located in the Upper Peninsula of Michigan. The low grade iron ore deposit consists of a mixture of magnetite and hematite with chert, jasper, quartz and various iron silicates (1). The ore is beneficiated by magnetic separation and anionic flotation of the iron minerals with chemical depression of the silica. The magnetic concentrate makes up about 75% of the concentrate. The concentrate is pelletized at the rate of 2.0 million LTPY of pellet production. The concentrator facilities were started up in 1959 and the concentrate was marketed as sinter feed until 1963 when the concentrator was expanded and the pelletizing plant was added. The pellet plant now consists of regrinding, elutriation, filtering, balling and induration. The pellet machine is a straight grate which employs updraft drying and cooling and downdraft drying, preheat and firing. It is necessary to regrind the concentrate before pelletizing. The con-centrate is 60% passing 325 mesh, with a surface area of ±lOOO cm2/Gm, and must be ground to about 83% passing 325 mesh, 1600 cm2/Gm blaine surface area, for pelletizing. The energy for regrind has been reduced from 12.5 KW per LT to 8.80 KW ate of 2.0 million per LT. This was the result of changes made in the concentrator where originally a coarse spiral concentrate, instead of the magnetic concentrate which is screened on fine screens to reduce the coarse fraction and prevent overgrinding before flotation, was produced. Also in 1968 an additional concentrating line was added to the concentrator which employs more grinding power than the other three lines. The demand for a high iron grade and lower silica pellet resulted in the investigation of different schemes of upgrading the reground concentrate which had more iron values liberated during grinding for surface area. The reagentized material presented many problems, mainly in selectivity trying to flot the iron and with high reagent consumption having to dereagentize the concentrate for amine silica flotation, in the various flotation systems tried. Tests were then conducted with elutriation (2) which proved satisfactory by removing the lower specific gravity, fine gangue material from the heavier material with the

Jan 1, 1977

By Frank E. Kottlowski

Widespread high-calcium (HC) limestones in New Mexico and adjoining areas, are low in magnesium, but some units include shale interbeds that would be deleterious for usage in sulfur removal. In southwest New Mexico, southeast Arizona, and adjoining parts of Mexico, limestones in the thick Mississippian Escabrosa, Pennsylvanian-Permian Horquilla, and Cretaceous U-Bar units are HC as are strata in the Mississippian Lake Valley, Pennsylvanian formations, Permian Hueco, and parts of the Permian Capitan Limestone of south-central and southeast New Mexico and west Texas. In north-central and central New Mexico, many limestones in the Pennsylvanian Madera Formation are HC as are some of the Cenozoic travertines. In northwest New Mexico, where the present-day mine-mouth coal- fired power plants occur, there are no HC limestones, but to the north in southwest Colorado some beds of the Mississippian Leadville Limestone and Pennsylvanian Hermosa Formations are HC. HC limestones considered contain at least 95 percent calcium carbonate and less than 3 to 5 percent magnesium carbonate. Limits for other impurities are alumina, 1 percent; silica, 2 percent; sulfur 0.05 percent; phosphorous, 0.02 percent; and iron oxide, about 1 percent. Chemical and physical requirements differ slightly depending upon the ultimate use.

Jan 1, 1995

By E. R. DeMen

In late 1965 General Mills announced the availability of a new liquid ion exchange reagent, LIX®-64, for the recovery of copper from various solutions, such as dump leach liquors. Acceptance of this material by the copper industry has been gratifying. A number of pilot plants have been operated, and at this writing there are four commercial plants either in operation or under construction. The properties and operating characteristics of this reagent have been described in previous papers.1,2 LIX-64 is quite effective and selective for copper extractions although partially limited in pH ranges, losing extraction efficiency as the acidity of the feed solution increases to below pH 1.0. Also, the LIX-64 content in the kerosine carrier was limited to about 10 volume percent (except for special cases) because of rapidly decreasing phase disengagement rates above this content. This in turn led to large plant capital costs, as the organic flow rates had to be in- creased (rather than LIX-64 content) to extract the copper from high content liquors. This was true in all circuits where the feed copper content ran above 2.0 g/l copper. A reagent was needed which would extract copper from more acidic liquors (or higher copper content liquors) and which exhibited improved phase disengagement characteristics with reagent contents up to 30 volume percent. General Mills is pleased to announce the availability in commercial quantities of a new and improved reagent, L+-64~. This reagent broadens the pH range in which copper can be extracted, and exhibits superior phase disengagement characteristics. The improvement in the reagent has been noted in laboratory circuits, as well as pilot plant runs and commercial operations.

Jan 1, 1970