Search Documents

By T. P. Meloy

Current coal cleaning technology uses heavy media (HM) for the recovery of coal in particles larger than 1/16 of an inch. Through the use of float sink measurements of the feed and products to commercial HM unit operations, a selection function, sometimes called Tromp curve in the coal industry, can be computed. Since the selection function is a plot f the probability of a particle appearing in the float versus the particle density, the slope of the curve will be sharper at the point where the particle has a 50% chance f appearing in the float. Thus, the separation will be better. Fine-tuning a unit operation or a circuit of unit operations requires that the selection function be accurately known. By current practice, it is difficult to obtain an accurate measure of the slope because, when the selection function is plotted versus density, the data forms an S-shaped curve which lacks data points near the 505 point of the curve. This lack of sensitivity in measuring the slope means that small recovery improvements cannot be detected; thus, only large improvements are measurable. Since most engineering improvements are small when individually considered, but large when aggregated ever many small improvements, this lack of measurement sensitivity rules out the slew march toward improved efficiency. This paper presents a method of analyzing heavy media selection functions resulting in a far more effective measure of the selective function slope. Furthermore, this improved method is applied to a number of industrial coal cleaning plants for both heavy media and heavy media cyclones. Using the work of Hudy (1968), and Deurbrouck and Hudy (1972), selection functions for individual unit operations in each plant are calculated as a function f particle size as well as density.

Jan 1, 1982

By Vas P. Srinivasa

This paper examines the role of the heavy media separator in the mineral industry. Procedures used in selecting the separating vessel, developing the process flowsheet, and designing a heavy media circuit are discussed. For comparative purposes, the capital investment and operating costs of different types of operation are included.

Jan 1, 1981

By E. L. Michaels

Laboratory and pilot scale tests have been made to deter- mine the utility of heavy media separation, particularly a cone type separator, as a means of recovering aluminum from shredded municipal solid waste. The effect of the method of shredding on the behavior of aluminum in a heavy media system was deter- mined. Two-stage pilot scale heavy media separations were made with size fractions of shredded refuse. Recoveries of aluminum, as well as other components of the refuse, were measured and medium losses were determined. The experimental results indicate that with certain reservations a heavy media cone system can be utilized for aluminum separation and recovery from shredded and air classified municipal solid waste. Observations made using two-stage heavy media separation in a drum unit are included. Qualitatively, the results from the two types of separators are similar.

Jan 1, 1974

By Frank F. Aplan

Introduction Heavy media separation (HMS), also called dense media or float¬sink separation, is one of the newer forms of gravity concentration. Though the concept can be traced to the last century, the process has enjoyed its major growth since 1940. Heavy liquid separation is a mutation. The heavy media process is used extensively to clean coal and for the concentration of a wide variety of ores such as those of iron, lead-zinc, chrome, manganese, tin, tungsten, fluorspar, magnesite, sylvite, garnet, diamonds, gravel, etc. It may be used where ever a significant density difference occurs between two minerals, and commercial separations are typically made in the range of 1.3 to 3.8 sp gr. The particle size treated ranges downward from 6-8 in. top size. Particles greater than about 1/16-in. (10 mesh) may be treated in a "static" bath, though for reasons of separation efficiency, + 1/2 -in- feed is usually preferred. For particles less than this size, separation in a heavy media cyclone is generally used. The flowsheet of a typical heavy media process, in this case one using a ferrous medium, is shown in Fig. I. In essence, the process consists of: (1) preparation of the feed usually by wet screening to remove undesired fines, (2) heavy medium separation, and (3) removal and recovery of the medium from the separated products. Many muta¬tions of the basic scheme are possible and numerous options are possi¬ble. HMS offers the following potential advantages:12 1) Ability to make sharp separations. 2) Ability to change the specific gravity of separation quickly to meet changing conditions. 3) Ability to remove products continuously. 4) Ability to treat a broad size range of products. 5) Ease of start-up and shutdown without loss of separating efficiency. 6) Relatively low medium cost and low media losses. 7) Low operating and maintenance costs. 8) High capacity with the use of relatively little floor space. 9) Relatively low capital investment per ton of capacity. The process may be used to produce a finished concentrate, two finished concentrates, or a concentrate and a middling of differing quality, or a preconcentrate by rejection of unwanted gangue. It is an ideal method for the reprocessing of coarse waste dumps. The greatest use for the process lies in coal cleaning and in the preconcentration of ores. The relatively inexpensive heavy media process may be used advantageously to reject large quantities of coarsely crushed gangue. When used in this way, the process will allow: (1) the use of lower cost but less selective mining methods with the "overbreak" material being removed at the front end of the concentrator or preparation plant; (2) a substantial reduction in the quantity of ore that must be finely ground for subsequent mineral liberation and separa¬tion. Since comminution is often the single most expensive step in beneficiation, it is desirable to eliminate as many essentially barren pieces of rock as possible before the grinding step, (3) a decrease in overall plant capital cost per ton of concentrate since the size of the plant from the dense medium step onward will be smaller. Several general references are available,12-18 though much of the technical data on the process is widely scattered in the general litera¬ture. Heavy Liquid Separation Organic Liquids Given sufficient settling time, it is possible to make a perfect separa¬tion between two particles of differing density by placing them in a liquid whose density is intermediate between the two. This means of achieving a perfect separation has proven to be elusive because of problems in feed preparation, particle settling rates, operational considerations, and economic constraints. There are a wide variety of heavy liquids that could be used, most of them halogenated hydrocarbons, and a few typical examples are given in Table 4. These liquids are most commonly used in ore dressing for the laboratory fractionation of ore particles on the basis of specific gravity. Laboratory Separations. Using liquids typified by those given in Table 4, separations are made to develop either the standard washability curves used to estimate the response of a given sample to gravity concentration or to prepare a partition curve to evaluate the effective¬ness of a given gravity separation process or piece of equipment. A typical washability curve is given in Fig. 2.19 Such curves are generated for raw coal, e.g., by treating either the whole or various size fractions of the sample in a series of heavy liquids and analyzing the various specific gravity fractions so produced. The procedure is relatively simple for coal samples because of the ready availability of a wide variety of relatively low cost heavy liquids in the density range 1.2¬-2.0. For ores the problem is much more complicated, because only a few high density liquids, all of rather high cost, are available. Parti¬tion curves are generated in the same manner by treating the separated products in the same liquids. Greater details on the procedures to be used in heavy liquid separa¬tions are to be found in the literature (for coal, Refs. 13, 14 and 19 and for ore, Refs. 20 and 21). For testing coal, calcium and zinc chloride solutions have been used extensively in the past, though today halogenated hydrocarbons (available under the trade name Certigrav) are the preferred media. The liquids shown in Table 4 may

Jan 1, 1985

By Edward Skolnik

The concept of using fluid dense media to separate heavy ore constituents from the lighter gangue dates back to 1858, when it was patented by Sir Henry Bessemer. Its use in coal did not begin until after 1917, however, when Chance invented a process (which bears his name) in which lighter coal floats in a suspension of fine sand in water while heavier refuse sinks. Conklin used fine magnetite in suspension as a medium for floating anthracite in 1922, DuPont designed a plant employing organic liquids in 1936, and Belknap used a solution of calcium chloride (which Bessemer had suggested, among other media) in 1937. Separation of magnetic media by magnetic separators from the suspensions in which they were carried was introduced in a Butler Brothers ore concentrator pilot plant in 1937. The media first used were crushed steel and various grades of ferrosilicon. Since 1940, when American Cyanamid used magnetic separators to recover and clean magnetite in a coal washing circuit, virtually all heavy medium circuits have been of that type. As long as static baths are employed, as they are in the processes above, coal smaller than 9.5 mm or 6.4 mm cannot be cleaned economically in heavy medium. The settling velocities of the fine material are very low, and consequently the time required to separate the lighter coal from the heavier refuse becomes excessive. In addition, stray currents in the vessel and the upward velocities induced to keep media solids in suspension affect the finer solids to the degree that physical size becomes a more important factor than specific gravity.

Jan 8, 1980

By David G. Chedgy, Edward A. Zawadzki, Robert D. Stoessner

Extensive research and testing in commercial facilities has clearly demonstrated that heavy medium cyclones are the most effective process for cleaning a 0.6 x 0.15mm (28 x 100 Mesh) coal at low separating gravities, less than 1.35. This paper describes testing performed to deter- mine system characteristics at these lower gravities and the type of circuitry required to maximize performance. The results of these studies include both pilot and commercial scale tests of cleaning 0.6 x 015mm (28 x100M) coal.

Jan 1, 1988

By Paul Dean Proctor

The known northern ore zones of the New Lead Belt of Southeast Missouri extend to the drainage divide between the Meramec River draining north and east and that of the Black River draining southward. Intensive geochemical studies related to the environmental impact of the new mining area have been carried out in the vicinity of some of the newly developed mines, mills and smelter complexes (Bolter,1970; Gale, et al, 1973; Wixson, et al, 1969, 1977). Other investigations have related to fringe studies of the Northern New Lead Belt and the possible additions of heavy metals to the surface waters, stream sediments and selected aquatic life (Proctor, et al, 1975, 1976). Similar studies have been completed in the Joplin area in the Tri-State district, and in the fringe area near Springfield, Missouri (Proctor, et al, 1974). A surface geochemical study is currently underway on the lead-zinc-copper-cobalt-nickel province near Fredericktown, Missouri (Proctor and Sinha, 1977). This report summarizes some of the distribution patterns of heavy metals in the waters, stream sediments and selected aquatic life in the Upper Meramec River drainage basin just north and west of the known northern portions of the New Lead Belt of Southeast Missouri. The region studied includes the site of the proposed and somewhat controversial Meramec Dam and the reservoir site behind it. Some 3905 km2 (1508 mi2) are included within the drainage basin of the Upper Meramec River. Six distinct drainage areas are included within the drainage basin; 1) a combined, lightly industrialized and farm area around Rolla and Salem, Missouri representing the Dry Fork drainage; 2) a primitive, mostly forested area with some farms and cattle rancheseast and north of Salem, Missouri comprising the Upper Meramec River

Jan 1, 1977

By J. L. Boyd

The mining and processing of basic metals relies on water as a medium for transport. Metallurgical ores are ground, concentrated, leached and refined in an aqueous medium. Water is used for temperature control during processing and in air pollution abatement during smelting. All of these process steps result in liquid wastes. Many of the aqueous wastes from ore processing areas become the raw product for a second stage and water recycling may begin. The point at which water recycling or reuse has been initiated in the past, rather than water discharge, was where water conservation was manditory due to a shortage, where process conditions would allow or benefit from reuse, and where economic considerations demanded reuse. The Fontana, California plant of Kaiser Steel Corporation is an example of an integrated steel plant that was forced to practice water conservation and reuse due to its location in an arid environment.1 Only a small amount of water required to maintain the water reuse system in balance with respect to dissolved solids and product quality is discharged. The Butte, Montana copper ore processing plant of The Anaconda Company obtains 66% of the water required for production by recycling, after clarification and chemical treatment, 30 MGD of wastewater from its tailings ponds. This operation is estimated to save the company about $1200/day over a once through water system.2 Here plant location and economics favored water reuse.

Jan 1, 1975

By R. Markovic

The objective of this research study was the investigation of heavy metal removal from wastewaters of the "SARAKA" stream by using low-cost materials. These wastewaters flow into Krivelj River and through the network of existing rivers into regional water reservoirs. Sawdust, cardboard and fly ash were used as reactive materials in laboratory studies. Sawdust was obtained from oak and fir-wood while fly ash from heating station Bor, bitter-oak and oak. Experiments were carried out using real Saraka stream wastewaters and the degree of removal for iron, copper, manganese and zinc was investigated. The content of these heavy metals in Saraka stream wastewaters was under the limit of III and IV class of water (Law on Water - Official Register of the Republic of Serbia). Parameters such as flow rate of water, pH and effluent volume, contact time between water and reactive material, etc, were monitored during the experiments. All used materials give satisfactory results for iron and other heavy metals removal; the highest degree of removal was obtained by using fly ash.

Jan 1, 2006

By D. Leppert

Large deposits of natural zeolites may provide cost-effective alternatives for treatment of soil and water contaminated ) with heavy metals and radionuclides. Research on the Bikini atoll demonstrated that addition of clinoptilolite to the soil significantly reduces cesium uptake by plants. Re- search on the potential use of zeolites in soils at Bunker Hill, ID indicated only minor benefits at very high contamination levels vs. US Bureau of Mines (USBM) work on the use of zeolites for treatment of mine waste waters emphasized problems with natural waters that previous studies have not addressed. High levels of competing calcium in natural waters significantly decrease the effectiveness of zeolites for heavy metal sorption and may limit the usefulness in these applications.

Jan 1, 1991

By D. Leppert

Clinoptilolite zeolite may offer attractive, cost-effective alternatives for remedial cleanup of old minesites, smelters and other sites with heavy metal contamination. Previous research demonstrates the relatively strong affinity of clinoptilolite for numerous metals and clinoptilolite displays a particularly strong affinity for lead (Loizidou and Townsend, 1987), one of the most toxic and problematic heavy metals. Since clinoptilolite can also selectively absorb some radionuclides and organic compounds, it may offer practical solutions to a wide variety of environmental problems.

Jan 1, 1989

By G. Gaidajis

Sea water samples collected from coastal waters in the vicinity of the Stratoni mining operations, in North-Aegean Sea were analysed for dissolved metals and elements. The maximum concentrations observed were one to three orders of magnitude lower than the environmental limit which coincides with the quality of sea waters suitable for swimming purposes. The quality of the coastal sea waters are affected by the natural mineralization of the area and the urban activities drained through local small rivers, the past mining activities present in the sea bottom sediments in the form of disposed tailings, and finally by the presence of the adjacent Mill-Flotation Plant. The relative importance of the treated final effluents discharged from the mining operations is considered to be insignificant.

Jan 1, 2006

By F. Sachanidis

The lignite surface mines of Ptolemais basin operate according to special environmental terms regarding the concentrations of heavy metals and trace elements in water discharges. Based ?n the results of lab analyses and in-situ measurements conducted so far it is concluded that the concentrations of heavy - toxic metals and other trace elements are low or negligible. The deviations from the upper concentration limits specified by laws and regulations are rare and non-systematic both on their spatial or temporal distribution. The same results prove also the relation between water quality and type and nature of the sediments forming the Ptolemais basin and the carbonated and metamorphic rocks forming the surrounding mountain areas.

Jan 1, 2006

By F. L. Pirkle

A heavy mineral deposit about 1.6 km (1 mile) in length, 0.13 km (0.08 mile) in width and averaging about 3 m (10 ft) in thickness is exposed approximately 130 km (80 miles) east of Denver, along Interstate 70, in Elbert county, CO near the town of Limon. The deposit is exposed in a geomorphic feature known locally as Titanium ridge. The dominant heavy minerals, accounting for about 70% of the total heavy-mineral suite by weight, are ilmenite, garnet and zircon. The mineralized zone appears in a series of visually interpretable facies that are stacked vertically and represent subtidal, forebeach, backbeach, washover fan and aeolian depositional environments. These paleoenvironments are analogous to depositional environments represented by a modern heavy-mineral bearing facies tract on St. Catherines Island, Ga. Thus, Titanium ridge provides evidence that heavy-mineral accumulation models for late cenozoic deposits in the Georgia and Florida coastal plains are applicable to heavy-mineral deposits of the Western Interior subsurface and, by implication, the Western Interior Seaway, extending from Mexico to the Canadian Arctic.

Jan 1, 2012

By Jr. Garnar

Heavy mineral mining has been a relatively small but important Florida industry for over sixty years. Geology of the Florida heavy mineral deposits is similar. Each formed along active coastlines after which the titanium minerals were upgraded in TiO2 by post depositional oxidation and leaching of the iron. There are four heavy mineral plants currently Operating in Florida. Ore is mined by dredges and the heavy minerals concentrated by gravity separation. The heavy mineral concentrates are further processed with high tension and electromagnetic separators to Produce titanium mineral concentrates for TiO2 pigment manufacturing plants. Zircon sand is produced as a co-product at all of the Florida plants. Staurolite is produced by Du Pont and Titanium Enterprises. Du Pont also markets a kyanite-sillimanite product. (Monazite is produced by Humphreys and Titanium Enterprises). Reclamation of mined-out land is an important part of heavy mineral mining. At the Du Pont plants soil is removed ahead of the dredge and placed over the quartz sand tailings. Grass is planted after fertilizing. A year later the land is fertilized again and pine trees planted. Most of the heavy mineral deposits now being mined will be nearly exhausted by the end of the century. New deposits to be mined in the 21st century will probably be smaller and lower grade than those now being mined. Advances in mineral processing technology will have to be made to allow these lower grade deposits to be mined economically.

Jan 1, 1978

By F. L. Pirkle, D. L. Pirkle, E. C. Pirkle, W. A. Pirkle

Heavy minerals have been mined from the sands of the United States’ Atlantic Coastal Plain since the early part of the twentieth century. Production of ilmenite from beach sands near Mineral City (Ponte Vedra), Florida, began in 1916. The first reported large-scale recovery of zircon in Florida was reported from this deposit in 1922 and of rutile in 1925. These operations ceased in 1929. Today the Ponte Vedra Country Club and Golf Course is situated in the center of the former mining site. In 1942 heavy-mineral operations were established on 202 hectares of land situated in Duval County, Florida. The location is about 16 kilometers east of the center of Jacksonville, Florida, in an area known as Arlington. This operation demonstrated that low-grade sand containing only 2 to 3 percent titanium minerals could be concentrated economically with the Humphreys spiral and that the oxides could be separated from the heavy silicates by electrostatic methods. Much of this area is now covered by a large mall and is a major retail- commercial center. Between 1958 and 1964 the Skinner tract, a deposit about 4 kilometers south of the above deposit, was mined. Today the area of this deposit is known as Deerwood, a gated country club community on the southside of Jacksonville. Further inland, E.I. du Pont de Nemours and Co. has been mining heavy minerals from a physiographic feature known as Trail Ridge since 1948, and a deposit near Green Cove Springs, Florida has been in production since 1972. Since the start of heavy-mineral mining in the southeastern United States, nine heavy-mineral ore bodies either have been or are being exploited in Florida and Georgia. Other deposits either have been lost to mining or are yet to be mined. These deposits have different origins. Some formed along shorelines at the heights of marine transgressions while others formed on regressional beach ridge plains during periods of temporary stillstands or slight transgressions. These different origins are reflected in the chemical and physical characteristics of the deposits. Ilmenite in older, more western deposits has a higher TiO2 content than ilmenite in younger, more eastern deposits. TiO2 content does not very with north-south direction. Garnet and epidote are absent or rare in the older Trail Ridge deposits, but progressively become common in the younger Duval Upland, Crestal Pamlico, and Holocene deposits. Grain size is coarsest for Trail Ridge sediments and finest for sediments in Duval Upland and Crestal Pamlico deposits. The average grain size for Holocene deposits is intermediate between Trail Ridge and Duval Upland deposits. The two models for the origin of the heavy-mineral deposits – deposits formed at the height of major marine transgression; and deposits formed during periods of temporary stillstands or slight transgressions that occur during a general marine regression; - are consistent with known sedimentological data and depositional trends.

Jan 1, 2005

By K. J. Stanaway

Concentrations of minerals between 3.5 and 5 specific gravity such as ilmenite, rutile and zircon in large accumulations of sand constitute "heavy mineral" placers. Two fundamentally different modes of formation characterize "trap" and "bed" placer variants. Smaller and generally higher grade trap placers form during sediment erosion or reworking. Because of their smaller size, they rarely yield economic heavy mineral deposits. They become economic, either if they contain more valuable "heavies" such as gold, or, if they occur within or near much larger but lower grade bed placers. Bed placers form during sediment accumulation episodes in any environment and lithofacies where mineral supply and fluid dynamics are favorable. Three heavy mineral deposits are discussed to illustrate bed placer geology and how trap placers occur with and relate to them.

Jan 1, 1991

By C. F. Curry

In the early 1940's Humphreys Mining Company in Florida pioneered heavy mineral mining with a dredge in the United States, In 1948 Du Pont, in conjunction with Humphreys, opened their first of two mining operations recovering a titanium dioxide product in Florida. Later on in 1952 Du Pont opened their second plant, both of which used a cutterhead suction type of operation. This process is also used in heavy mineral mining in Australia and Africa. In 1957 ASARCO started prospecting in New Jersey. Test borings indicated a large deposit of ilmenite bearing heavy mineral sands had been deposited and concentrated in an area near Lakehurst in central New Jersey. Humphreys Mining Company was contacted about the possibility of mining the ASARCO New Jersey property in much the same way as Du Pont and themselves were doing in Florida. An extensive study was made to determine the economic feasibility of mining the ASARCO property. During this study, extensive test drilling and samples for a pilot plant were taken.

Jan 1, 1975

By William R. Yernberg

The Fifth International Heavy Minerals Conference (HMC) was held Oct. 16-19, 2005, at the Marriott Sawgrass Resort in Ponte Vedra, FL. With SME as sponsor, the 2005 conference marked the first time that the HMC was held in North America. The conference is held every two years and provides an important forum for professionals in the heavy minerals and related industries to meet and discuss issues related to heavy mineral exploration, mining, processing and marketing. Previous locations included Australia and South Africa. The conference consisted of technical presentations, field trips to heavy mineral operations, a trade show and social activities. It was appropriate that Ponte Vedra was selected as the location for the conference. Ponte Vedra, located on the Atlantic Coast 17 km (10 miles) southeast of Jacksonville, FL, is the birthplace of heavy minerals mining in North America. Ponte Vedra beaches were mined from 1916 to 1929 in what was then called Mineral City. Though Ponte Vedra is now a golf and beach resort, there are still four heavy mineral mines operating within an hour’s drive. Today the Ponte Vedra Country Club and Golf Course is situated in the center of the former mining site.

Jan 1, 2006

By H. A. DeMirjian

Oil production rate and ultimate primary recovery from a heavy or viscous oil reservoir is usually limited to a very small fraction of the original oil in place. Typically, normal production rate is in the range of up to 10 barrels per day and expected ultimate cumulative production is up to 10% of in place values. Heavy oil reserves are not all alike. The physical properties of the rock, the liquid hydrocarbons, and depths of the deposits are so different that each reservoir poses a unique enhanced oil recovery problem. In some reservoirs thermal recovery by internal heat generation or external heat injection has been successfully exploited. In other reservoirs, mining the oil bearing formation for oil recovery by surface processing has been practiced. This paper will present an overview of the heavy oil recovery state of the art and discuss the critical factors leading to the decision for selection of a conventional hydrocarbon recovery or mining and extraction processes.

Jan 1, 1978