Search Documents

By R. R. Klimpel

The efficiencies of plant-scale comminution processes are often evaluated by various indices calculated and/or measured somewhat independently of the performance of any associated downstream froth flotation processes. To compare specific comminution factors, such as energy utilization, media consumption and equipment utilization time, comparisons of comminution efficiency independent of flotation behavior are appropriate. However, as increasingly detailed plant-level information is gathered on the joint and highly interactive nature of comminution and froth flotation, it is becoming even more obvious that knowing and using simple efficiency indices are not enough. What is needed are more performance-related measures of the efficiencies of the combined size reduction froth flotation system for effective plant-level economic optimization to occur. The purpose of this paper is to present examples of some of the important interactions that influence the joint efficiencies of size reduction and froth flotation processes.

Jan 1, 1999

By Romeo S. Jurani

Bulkspray cooling has been economically applied in cooling the hot environment of South African gold mines for the past two decades. Its success in that country led to its introduction at Gulf Mineral Resources Co.'s Mt. Taylor Mine in 1981 when increased drifting imposed additional cooling requirements. The bulkspray cooler developed and used at Mt. Taylor has a heat transfer capability of about 500 to 1500 kW. It is compact and portable, designed to be moved as required to maintain working temperatures in the advancing drift faces.

Jan 1, 1983

By R. Sharon

Barrick Goldstrike Mines, Inc. Betze-Post open pit operations, located in northeastern Nevada, have experienced slope instability attributed to the presence of generally weak rock mass conditions, local adverse structural geology and perched groundwater. Ground movements are monitored with acombination of optical survey, extensometers, inclinometers, and time domain reflectometry (TDR).The slope monitoring system at Goldstrike includes two robotics theodolites, which provide real-time coverage for all highwall areas. Survey instruments are housed in specially designed climate controlled shelters in locations where all slopes can be observed. A “remote” computer housed with each theodolite collects data. The “base” computer, located in the mine offices, is used to access data from the remote computers via radio modem.

Jan 1, 2000

By W. Petruk

Mineral liberations that would be obtained by grinding an ore to a specific size can be predicted by analyzing unbroken ore pieces, and mineral liberations in ground ores and mill products can be determined directly by image analysis. Predictions of mineral liberations are made by measuring size distributions and textures of mineral grains by image analysis, and using liberation models. Ground ores and mill products are analyzed to determine the proportion of mineral that is liberated, and the data are used to evaluate mineral behaviour during mineral beneficiation. The liberation data for minerals in a suite of mill products from a circuit are processed by a materials balancing technique to calculate recoveries of minerals in different types of particles throughout the circuit. The liberation-materials balance data define mineral recoveries; define the behaviour of an ore in a concentrator, pilot plant or bench test; and indicate whether recovery improvements are possible and/or feasible.

Jan 1, 1991

By Tom McDonald

Test work and plant operation confirmed that semiautogenous (SAG) milling is a viable option for Inco's milling rationalization project at Sudbury only if pebble crushing is included. Throughput increases more than 50% with pebble crushing incorporated into the comminution process. The finer product of high-speed pebble crushing provides further energy savings. The unconventional approach of pumping the pebble crusher product, while simplifying plant layout, has produced challenging wear problems. Inco Ltd.'s Sudbury operations are located in northeastern Ontario, Canada, about 400 km (250 miles) north of Toronto. Inco has 11 operating mines around the rim of the Sudbury basin. The mines currently produce about 11 Mt/a (12 million stpy) of ore. This ore contains pentlandite, pyrrhotite and chalcopyrite in mafic host rocks. The milling facilities are designed to produce 108.8 kt/a (240 million lbs/ year) of nickel as concentrate. This concentrate is further processed through Inco's smelting and refining facilities to produce nickel, copper and several other metals. Before 1991, -200 mm (-8 in.) ore was shipped to two primary mills. The Clarabelle mill had a design capacity of 29 kt/d (32,000 stpd). Frood-Stobie had a capacity of 16.3 kt/d (18,000 stpd). The flowsheets of these mills were similar. Two stages of open-circuit crushing were followed by rod milling and closed-circuit ball milling. The product from the comminution circuit, at 12% +250 mm (+65 mesh), was first passed through magnetic separators to recover magnetic pyrrhotite. It was then sent through a four-stage flotation process. The first two stages produced a high-grade copper-nickel concentrate. The final two scavenger stages produced a low-grade copper-nickel concentrate containing nonmagnetic pyrrhotite.

Jan 1, 1992

By James F. Albus, Vincent C. Grimshaw

High pressure fluid energy grinding, or jet milling, is a versatile method of continuously fracturing solids into fine particles to gain substantial increases in exposed surface area Applications in industrial minerals grinding include calcium carbonate, talc, barytes, mica, diatomaceous earth, bauxite, rutile, coal, kaolin, sepiolite, diamonds, etc The basic principles can be extended to provide continuous drying and delivery of discrete par¬ticles from a wet process slurry The main design and operational features of jet mills and dryers are described, relating energy consumption for both air and steam milling and hot air drying techniques Mean particle sizes in the order of 1 micron are achievable from pre-milled feeds, or maintained from similar slurries in the drying mode Aspects of feed preparation and multi-stage processing are discussed

Jan 1, 1983

By Werner A. Ruemmele, Steven R. Wardwell

INTRODUCTION The first phase of the Los Angeles Metro Rail Project consists of 7.1 km (4.4 miles) of subway and stations running through downtown Los Angeles from Union Station to MacArthur Park. Shank-Ohbayashi has two of the tunnelling contracts on this initial phase: A-171 and A-146. Contract A-171, the Wilshire/Alvarado Line, involves tunnel construction beneath 7th Street from the 7th/Flower Station to the Wilshire/Alvarado Station. The project consists of the excavation and lining of 3000 m (9900 ft) of twin-bore, 6.7 m (22 ft) excavated diameter, 5.5 m (18 ft) finished diameter subway tunnels. Contract A-146, the 5th/Hill to 7th/Flower Tunnels, comprises 1220 m (4000 L.F.) of twin-bore tunnel identical in cross section to the tunnels in Contract A-171. The majority of the excavation on Contract A-171 is beneath city streets in a weak siltstone/claystone bedrock with cover varying between 10 m and 25 m (32 ft and 82 ft) to the street surface. Approaching the 7th/Flower Station some fine-grained alluvium is encountered. The tunnels on both contracts are excavated with an open face digger equipped shield. On Contract A-146 the tunnel alignment is a 305 m radius curve of approximately 550 m (1800 L.F.) length underneath several multi-storied buildings of various construction. Excavation is still ongoing on Contract A-146. The contractor's choice for initial tunnel support on both contracts is a system of precast concrete segments similar to what the contractor had used on 7 miles of tunnel in Phoenix, Arizona, for the Arizona Department of Highways.

Jan 1, 1989

By K. P. Unrug, E. Thompson, S. Nandy

The method of coal pillar design involves primarily two aspects: the geometry of the pillar and the strength of the coal. However, the strength of the coal has to be emphasized with respect to the entire pillar dimension rather than isolated strength values of coal samples taken and measured from different locations. As of now, the presently applied pillar design systems do not specify clearly what the coal sample strength really represents. The intention of this paper is to introduce the concept of seam strength as opposed to the current practice of using coal strength as a prime design criteria in the formulation of pillar calculations. Seams are most often composed of multiple layers of coal, partings, and bone in various configurations, changing within the vertical section of the seam even in relatively close locations. The difference in strength between the weakest and strongest component of the coal seam could be as much as five times or more. An experimental approach based on multiple uniaxial compressive strength tests performed on coal samples from the Coalburg and Warfield seams from eastern Kentucky was undertaken. Analysis of the results led to the conclusion that for pillar dimension calculations, both the weighted mean of the seam strength and the strength of the weakest stratum should be considered, rather than the relatively vague aspect of coal strength. The design of pillar dimensions based on the aforemen¬tioned criteria should assure a more realistic design performance.

Jan 1, 1987

By Ernest Koenigsberg

In 1961 Lerchs and Grossman presented a method, based on graph theory, to determine the optimum ultimate pit limits for an open-cast mine. At the same time they demonstrated a dynamic programming algorithm for the optimum pit limits for a two-dimensional open-cast mine. Since then many methods for determining optimum limits for three-dimensional mines have been programed, and even more have been reported in the literature. The methods include computer "simulation" of the manual methods used by engineers, the development of sets of conic sections and fitting to exclude overlap, integer linear programming (and its equivalent network flow model), and dynamic programming. Many of the methods do not guarantee optimal solutions but seem to satisfy the user. Other reported methods have never been applied, partly because they did not yield optimal solutions. We have developed a three-dimensional dynamic programming algorithm which requires a single pass through the data. Large problems can be solved on a small computer because only a small part of the data is required at any time. In this paper we will review the state of the art and to demonstrate the connection between linear programming (and network flow) models and the dynamic programming method.

Jan 1, 1982

By Dinah O. Shumway

California's annual production of >11 million tons of cement, at a value of over $640 million, comes from eight companies, which operate 11 plants. Cement is California's second most important mineral commodity, representing 25% of its total annual mineral production. Although most of the cement produced is consumed within the state, current export locales include the Pacific Northwest, Nevada, Arizona, Utah, and New Mexico. An enumeration of the components required to produce cement is deceptively simple: calcium oxide (65%), silica (20%), alumina (4-5%), iron (3-4%), and calcium sulfate (4%) as a retardant admixture. The last, and most expensive, ingredient in cement manufacture is energy. Detrimental materials in cement mixes include excess .magnesium, alkalis, heavy metals, sulfur, and other volatiles. Each of the 11 cement plants in California requires a unique chemical solution of combined raw materials to produce a uniform product: portland cement. The geologist proposing solutions for the additive raw materials in cement manufacture must have a thorough knowledge of a particular cement plant's needs. In the California cement market, keeping the costs of additive raw materials down is one way to also stay competitive, and using a combination of natural and waste materials as additive raw materials allows cement producers to stay competitive.

Jan 1, 1999

By H. C. Verakis, T. E. Lobb

During the past decade, approximately 5 billion pounds of explosives were used annually in the United States. Most of this quantity of explosives was used by the mining industry, with coalmining being the dominant application for explosives. Considering the large amount of explosives used, the accident safety record for the mining industry has improved significantly over the past several decades. Although blasting accidents usually represent a small percentage of the total number of mining accidents, they continue to occur and the severity of these accidents is disproportionately high compared to the other mining accidents. This paper is an analysis and summary of mine blasting accidents over the past several decades as they relate to surface coal mine operations. A compilation and review of surface mine blasting accidents from1978 through 2001 was made. The accident data was examined to identify the trends and primary causes, which continue to be blast area security, fly rock, premature blast, and misfires. Approximately 46percent of the causes of surface coal mine blasting accidents are attributed to blast area security, while fly rock, premature blast, and misfires represented an additional 50 percent of the causes. Accident categories were established based on the cause of the accident or the activity that was taking place when the accident happened. A discussion of the accident data is presented to increase hazard awareness and to emphasize safe blasting practices and MSHA requirements concerning mine blasting operations.

Jan 1, 2003

By M. Beus, S. Stewart, S. Iverson

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods and better hang-up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during the transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste-rock loads on chutes, walls, gates and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mockup of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were compared Loads on an active ore pass chute were measured

Jan 1, 2000

By Wayne F. Crockett, Martin H. Col

Gold, as a precious metal, has been sought for several thousand years. During this time economics have generally determined whether or not a deposit is minable. Today, few would spend $500.00 or $1,000.00 to produce one ounce of gold, yet most gold deposits currently being mined would have such costs if they were mined using the methods of the 18th century. Innovation has been the key to success in the world of mining. We are constantly having to look for new ways to mine deposits of lower grade, at greater depths, or with higher stripping ratios. The mining of placer gold deposits has always been subject to the volatile swings of the world price and the constant rise in production costs. The rise in costs is compounded by the drop in overall ore grades. Occasionally, a major technological innovation will dramatically reduce the costs of placer mining to allow previously marginal or unminable deposits to be mined at a profit. The continuous bucketline dredge was the last such major innovation in the gold placer mining. The continuous bucketline dredge has allowed large volumes of placer deposits to be picked up and processed on a continuous basis. Unfortunately, as the overall grade of the deposit declines, it becomes impossible to process enough ore to pay for the operating costs. There are many gold deposits around the world waiting for the next technological innovation that will allow them to be mined. One such deposit has been the Grey River deposit near Greymouth in New Zealand. The deposit contains gold reserves of 8992 kg, yet the deposit has been sitting idle for many years because the average value

Jan 1, 1988

By Donald A. Dahlstrom

If you have ever driven on the Autobahns of Western Germany, you are well acquainted with the "fast lane." There is no speed limit; there are only two lanes in the direction you are going, and if you choose to drive in the fast lane, you had better be prepared to drive faster than anyone or someone will tailgate you with a constant screeching horn until you move to the "slow lane." The prize for this mastery of the fast lane is some kind of a "macho" feeling and getting to your destination sooner than your competitor. This has some comparisons with today Is liquid-sol id separation. We've certainly had our moments in the fast lane but we've also had other countries forcing us into the slow lane at times. It can be very embarassing when someone almost runs over your back and then shakes a fist at you as you shakily scatter to the much slower and overcrowded lane. Because of necessity, there will be many new improvements and added requirements in the next decades into the 21st century and beyond. Those countries and industries that can maintain the pace in the fast lane will be successful while the others may well be relegated to the non-competitive lane. Before considering what will be the challenges in the future for competitive liquid-sol id separation performance, it would be wise to review progress over the past forty years in this area. The author has to admit his ancient age and believes he can act as an evaluator of these many advances. To place the beginning of the 40 years (the author predates his initiation into liquid-sol id separation by one more year), the United States was still building smelters and operating them with little or no sulphur dioxide removal , practically

Jan 1, 1989

By M. A. Trevits, A. Ozment

"According to the Office of Surface Mining Reclamation and Enforcement Abandoned Mine Land Inventory System, in 2013 there were 98 underground mine fires burning in 9 states. This is considered by experts to be an underestimate for the actual number of fires nationwide. Abandoned mine fires, if left uncontrolled can burn for years and in fact, one of the most well-known mine fires in the US, the mine fire in Centralia, PA, which began in 1962 has been burning for over 55 years. In Centralia, the mine fire won the battle, despite suppression and control efforts, as most of the residents were bought out by the State of Pennsylvania and moved away. However, the world record for the longest-burning coal fire, which may have been started around 6,000 years ago in New South Wales, Australia is still smoldering. Suppressing a coal mine fire requires cooling the hot zones and removing any source of oxygen. If the workings are shallow, the fire zones can be unearthed and the burning rock mass can be quenched on the surface. If the workings are too deep to excavate, then the fire must be fought remotely through boreholes using a variety of agents including water, gas-enhanced foam and grout. Access to surface areas for drilling can be problematic due to topographic and property constraints. When this occurs, large areas of burning may go unaddressed or simply left to burn. Fire Solutions, Inc. has been investigating the use of gas-enhanced foam in concert with directional drilling technology. Gas-enhanced foam has the advantage of using less water and adds inert nitrogen gas to displace oxygen to infiltrate and suppress a fire. Directional drilling has the capability to steer a borehole to a specific place underground. Directional drilling has many advantages over conventional drilling technology as it can provide the least disruption to the ground surface, minimize surface preparation and reclamation costs, multiple sites can be accessed underground from a single site and thus treated simultaneously and it offers increased efficiency because it is not constrained by difficult terrain. This paper discusses the combined use of these two technologies and it is hoped that with the use of these two technologies the efficiency and capability to address mine fires will be significantly improved. INTRODUCTION According to the Office of Surface Mining Reclamation and Enforcement, Abandoned Mine Land Inventory System, in 2013 there were 98 underground mine fires in 9 states. This is considered to be an underestimate for the actual number of fires nationwide. Many mine fires are started by people burning trash where the coal seam or an abandoned coal mine is close to the surface. Other fire ignition sources include lightning and forest fires. Once ignited, a coal mine fire can easily spread into the remaining coal pillars and mine entries. Once established, the fire creates its own ventilation system supporting further combustion by drawing air down into the workings through unsealed mine shafts, fractures and surface subsidence depressions. As the coal left in the workings from the past mining operations burns, the mine void can collapse, causing subsidence and creating dangerous voids, damaging damage overlying surface structures and roadways. The products of combustion include smoke and noxious fumes such as carbon monoxide gas. These products are released to the atmosphere through fractures that develop within the ground surface, killing vegetation and creating serious health hazards [1]."

Jan 1, 2018

By R. C. Bunge

A magnetogravimetric separation is the consequence of two competing forces with opposing directions, i.e., magnetic buoyancy and gravitation (or centrifugal force). While magnetic buoyancy is a function of particle volume, gravitational force depends on particle mass, thus permitting a separation according to specific gravity. Since magnetic buoyancy is not a phenomenon of common knowledge, this chapter is meant to briefly introduce the theory of magnetogravimetric separations. A particle that is suspended in a magnetic fluid which is exposed to an inhomogeneous magnetic field experiences a repulsive force -the so called magnetic buoyancy. In order to illustrate this effect, an analogy with the more familiar hydrostatic buoyancy is drawn. Hydrostatic buoyancy occurs due to unsymmetrical pressure distribution 'above' and 'below' a suspended particle (fig. 1).

Jan 1, 1990

By Paul H. Johnson

The CH Leaching process is a new, more sophisticated, form of gold, silver, uranium and sulfide copper heap leaching wherein each layer of a multi-layered heap is divided into a number of independent cells, each of which are successively formed and leached in the top layer of the heap to their maximum economic recoveries, and then rinsed and sealed from further leaching. Triangular earth berms form the outside walls of the heap and a gridwork of rock-filled berms on top of the bottom pad form independent under- heap solution storage zones. The high degree of solution recirculation and staging that occurs in this process produces a relatively small volume of very rich pregnant solution. The cellular heap design and its mode of operation result in a uniform, intensive, long-term leach for all of the ore particles in the heap. Besides improved metal recoveries, the process appears to have several cost and operating advantages. In the CR2MR process, sulfuric acid and a soluble sulfide are added to a gold and/or silver pregnant leach liquor to precipitate most of the contained silver, mercury, copper, etc. as sulfides at a pH below 2.5. The other product of the reaction is solubilized HCN. Following a liquid-solid separation step, cyanide is regenerated in the supernatant solution by raising the pH to a level above 9.0. This process regenerates a portion of the cyanide used in the leaching step, removes contaminant ion species (silver, copper, mercury, etc.) from the leach solution and, in a subsequent step, recovers the gold in an enriched form. It is believed that substantial cost savings may be experienced by the use of this process in some gold and/or silver leach systems.

Jan 1, 1984

By Liyan Ren, Huayang Dai, Yingcheng Li, Enquan Wang

"Three-dimensional geological modelling of coal mines is critical to the sustainable development of the mining industry. On the basis of comprehensively analyzing 3D geological modelling methods, according to the available data of mine such as geological terrain maps, cross-sections and boreholes, we present a 3D modelling method by integrating ArcGIS and 3D GeoModeller. Our motivation is to integrate the advantages of both software modules in processing, converting, integrating and transferring geological information. Special attention has been given to the data structure and processing flow. We build a 3D geological model of the Xieqiao coal mine and successfully extract the geological framework of the strata in the 11118 workface, which is consistent with that of the actual explored geology.Introduction/Background Pertinent impediments such as a lower information degree, the out-of-date information infrastructure and the low level of information management and decision-making make it critical for there to be improvements in mines. Modern exploration technologies favour the construction of digital mine. Digital mine promotes the transformation of the mining industry by integrating information, automation and intelligence to build safe, efficient, high-yield, green and sustainable mines. Three-dimensional geological modelling and visualization of mines are at the core of digital mine. Compared with traditional 2D geological data, 3D models express the various geological phenomena completely, as well as reproduce the spatial distribution of geological units quickly, allowing for the prediction of mining subsidence, better decision-making and improved geological analysis. Modelling methods such as multi-DEM, tetrahedral grid and the generalized tri-prism that are based on borehole estimation and interpolation data are used to construct 3D models of mine geology (Chen 1995,Wang et al 2003, Wu 2004a); nevertheless, these methods cannot fully use multi-source mining data, whereas multi-source integration methods can be used to build 3D models (Kaufmann and Martin 2008, Zhao et al 2009) but require user interaction in model construction and low automation in model updates. During coal production, a plethora of geological data is accumulated. The organisation of discreteinformation under dynamic conditions and the extraction of meaningful information to better service for three-dimensional modelling is a meaningful work (Wu et al 2004b)."

Jan 1, 2017

By Derek J. McCracken, William G. Holroyd

Emery is a rock that at one time held a large share of the abrasives market. The introduction of synthetic abrasives, however has forced it to settle for only certain niches in the marketplace. This loss of market share is due mainly to the higher amounts of impurities and weaker internal structure that naturally occurring minerals have compared to manmade materials. The use of rocks and minerals as abrasives dates back to early man, who used flint, quartz, and other natural materials to fabricate various tools. During the 19th century, with the Industrial Revolution imminent, the character of the abrasives industry was changed forever as synthetics were introduced. Frank B. Norton is credited with producing the first manmade abrasive when, in 1855, he manufactured a vitrified grinding wheel using emery grit and clay. Before Norton's accomplishment emery had been the only commercially available abrasive. The latter part of the 20th century has seen synthetics capture an increasing share of the abrasives market from natural materials. The term emery is believed to have been derived from the words emeri (French), smeriglio (Italian), and smiris (Greek). The term corundum, for the principal mineral of emery, seems to have originated from kauruntaka, the Indian name for the mineral. GEOLOGY Emery is a gray to black, granular rock comprised of various minerals including corundum (A1,0,), an iron-bearing mineral (usually magnetite-Fe,O,, hematite-Fe,O,, or hercynite- FeAI,O,), and several trace impurities such as mullite, titania, silica, and magnesia. The hardness of emery normally ranges between 7 and 9 on the Mohs scale, depending on its mineral com- position and level of impurities. Corundum, the hardest mineral in emery, typically has a hardness of 9. The specific gravity of emery ranges from 3.2 to 4.5, also depending on mineral composition and purity. The crystallography of each mineral contained in emery differs somewhat. Corundum exhibits an hexagonal crystal structure, whereas magnetite forms within the isometric system, frequently as octahedral crystals. Hercynite, an iron spinel, is also isometric. Hematite has an hexagonal structure but often is found as botryoidal and reniform masses. Principal deposits of commerical emery are found in the United States, Turkey, and Greece. In the United States two emery producers in the Westchester County-Peekskill area and one in the Cortlandt County area of New York closed their mines in the late 1980s. Commercial production in the United States now comes only from the western Cascade Range in Oregon. The emery in New York has a typical A1,0, content of 41.5%. Most of the rock is not true emery because it contains a mixture of spinel and magnetite but very little corundum. The deposits are of Late Ordovician-Early Silurian age and consist of veins in which emery is mixed with olivine, pyroxene, and hornblende. The veins evidently were formed by contact metamorphism and are surrounded by Precambrian schists that contain mica, sillimanite, cordierite, garnet, and quartz. The deposits in Oregon were formed during Miocene time by the contact metamorphism of ferrunginous bauxite by intrusive lamprophyric dikes and plugs. Emery is found in thin layers bordering these tabular dikes, which are usually oriented perpendicular to bedding, and in "surficial placer deposits. The emery deposits in Turkey occur as small, massive, lens- shaped bodies and as surficial placers. They are believed to have formed during Permian and Triassic times. In Greece the principal site of emery production is at Cape Emeri on the Island of Naxos. These deposits consist of lenticular masses of emery surrounded by marble. They originated during Mesozoic time, evidently by metasomatic replacement. Smaller deposits on several other Aegean islands were formed by the metamorphism of bauxite or other alumina-rich materials.

Jan 1, 1994

By Cesar A. Busnardo

The carbonatite orebody in Jacupiranga is situated some 230km (140-mi) southwest of Sao Paulo and is mined by Serrana S/A de Mineragao, producing an apatite concentrate for fertilizer production and a calcite tailing for cement manufacture (see Figure 1). The orebody (Table 1) is mined by open pit and the total production is 4.5 million mt/year of carbonatite ore with a further 2.2 million mt/year of overburden. The carbonatite low-grade ore (Table 2) is fed to the concentration plant at 460 mt/h , comprising of four parallel lines of grinding, by rod mills 2.7m x 4.5m (9 x 15-ft), operating in closed circuit with hydrocyclones. The grinding circuit product is deslimed in four stages using hydrocyclones and the deslimed product is conditioned with corn starch and subsequently floated, using fatty acids as collector to, recover the apatite.

Jan 1, 1985