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By J. G. Groppo

Hyperbaric filtration was evaluated at the laboratory scale for dewatering fine coal cleaned by froth flotation. A laboratory pressure filtration procedure is described to obtain uniform cake structure from dilute slurries containing a significant amount of coarse material. Baseline tests were conducted varying filter operating parameters such as driving force, time, cake thickness, percent solids, viscosity and pH to determine optimum operating conditions for eventual application on a continuous pilot scale hyperbaric filter.

Jan 1, 1994

By Raymond Mancha

"Conventional" coal dryers really do not exist. What we really mean to say is that there are many and varied kinds of coal dryers -- and the "air handling problem" is really the only portion of it which has been approached for solution by conventional methods. It now appears that these conventional methods need supplementing by some new, relatively unconventional apparatus. In order to approach this matter with mutual understanding, here is a quick survey of the coal drying art. Figure #1 shows a McNally Pittsburgh Pulso Dryer, In the McNally Pulso Dryer, the coal is fed-onto the screen by a rotary feeder assuring even distribution of the coal. As the coal travels forward due to the action of the screen, it is subjected to a controlled pulsating flow of hot gases. T ese originate below the deck and are directed up through the moving bed of coal. Fines sifting through the deck are dried in the hopper below the screen as they fall through the hot gases to an evacuation screw. The coal remaining on the screen is dried to the desired degree when it reaches the discharge end. At this point, it is directed down into the evacuation screw to combine with the fines, or it may be discharged as a separate product. As the coal travel down the screen, it is subjected to intermittent upward currents of hot gases. These first distend the bed allowing the gases to come into intimate contact with the coal particles for rapid and efficient heat transfer. Then, as the flow of gas is cut off, the bed settles and the extreme fines sift through the screen preventing their being carried away into the exhaust system.

Jan 1, 1958

By C. A. Hollingsworth

The Deep Leg Flotation Cell was developed to solve a problem which confronted the Smith-Douglass Company on moving from one mining area to another. Poor recovery and, to some extent, inferior concentrate grade were encountered in the silica flota¬tion circuit. This was believed due to the softness of the phosphate which caused it to form slime. In view of the urgency of the matter, the problem was attacked from two angles. The first involved the development of a flotation cell which would not create slime and the second, a new or improved reagent for floating silica from phosphate rock which would be less sensitive to slime than reagents currently in use.

Jan 1, 1964

By Bruce C. Trent

In order to effectively model subsidence caused by underground openings, a two-dimensional computer code has been developed which couples near- and far-field response. The near-field is simulated by a discrete element block code and a finite difference code represents the continuum region in the far-field. The explicit equations allow rapid and inexpensive solutions to geometries which may lead to subsidence. Two sample problems are presented which illustrate the important features of the code.

Jan 1, 1979

By Neville T. Moxen, Stuart K. Nicol, Malcolm D. Engel

Ion flotation is a process in which ions of interest are complexed with a suitable surfactant molecule. A dilute solution containing these complexes is then aerated, under which circumstance the surface-active complex concentrates at the air-water interface and is transferred to a froth. The present work describes some of the phenomenology of this process and experimental work leading up to the design and use of a pilot scale laboratory facility. Early experiments suggest that selective recovery of gold can be obtained in a manner at least equivalent to conventional CIP processing at low capital cost. Under favourable conditions, upgrade ratios of gold ions of the order of 180: l have been achieved from reclaimed residue dam water with as low an initial gold level as 0.2ppm. Successful development of countercurrent ion flotation for concentrating solids-free gold solutions may offer a lower cost alternative to existing gold ore processing technologies, or in more secondary applications such as concentrating dilute gold solutions or heap leach runoff. The technology may also have more generalised applications to other heavy metal processing.

Jan 1, 1990

By L. S. Gourevitch, E. B. Kremer, A. Y. Fidlin, Y. M. Katsman, I. I. Blekhman

A new kinetic approach to simulation of fracture is given. The main object of the simulation is forecasting transformation of ore lumps size distribution in squeezing of ore layer between two planes. The approach rests on fundamental principles of energy and mass conservation and on new ideas about fracture physics connected with fractal geometry. On this base an integro-differen tial equation of layer crushing kinetics is formulated. This equation is similar to well-known kinetic equation of grinding, but here we use elastic energy density in place of time as an independent variable while selection function is considered by us to be dependent on this variable. Properties of the equation have been investigated by us and its analytical solution has been found. It allows to compute simultaneously both the evolution of the size distribution process of squeezing and force-displacement diagram. Results of theoretical calculations provide a good fit with experimental data.

Jan 1, 1995

By Maurice Jackson et a1

Golder Moffitt and Associates (GMA)", were commissioned to reassess a large metallic low grade orebody. One of the aims of the study was to estimate recoverable reserves. Recoverable reserves are here defined as ore reserves for a specific mining block size. The mining block is that block on which the decision that the material is ore or waste is made. Recoverable reserves take into consideration mining methods. New methods for solving this type of problem were recently developed in Geostatistics and so for this reason GMA called for the technical assistance of the Centre de Geostatistique (C.G). The complete estimation was done using the geostatistical techniques and programs of the C.G together with some of the programs of GMA. As the mine was in production at the time the study commenced it was-possible to make frequent checks on the estimated values using blast-hole data. The ore reserves were also estimated using the more conventional interpolation method of inverse square of distance weighting.

Jan 1, 1979

By Y. Ooishi, Y. Matsumoto, T. Arai, H. Ohta

The multi-circular face shield (MFS) is a new type of tunnelling machine for construction of the special cross section and has been put to practical use in 1988. The MF shield has two circular faces partially overlapped in a single shield machine and can construct the cross section shaped like glasses for the double track railway. And it is possible to equip two or more cicular faces horizontally or vertically, if necessary. During the development of the MF shield the experiments have been carried out for the purpose of estimating the excavatability and the face stability of the MF shield. As a result it was confirmed that the both types of MF shield (one with double faces aligned horizontally and the other with double faces aligned vertically) has higher performance in the face stability and lower value in the cutter torque and the total thrust than the conventional circular shield.

Jan 1, 1991

By Bruce S. Brown, Jeremy P. Haile

The construction of tailings facilities and heap leach pads for gold mining operations generally requires the installation of one or more impermeable liners beneath the structures to satisfy environmental regulations and prevent the leakage of gold bearing solutions. Liners are usually constructed using clay soils or synthetic membranes, such as high density polyethelene. Low permeability soil liners can be constructed from natural clays, well graded soils with only a small clay content, or sandy soils blended with a small quantity of imported clay such as bentonite or kaolinite. The permeability of such materials, prgperly pped with good quality control, generally lies in the range of 10- to 10- cm/s, and can be designed to meet minimum prescriptive standards set by regulatory agencies. Important benefits resulting from the use of clay liners include the slow rate of penetration of a saturated wetting front, the decrease in permeability of the liner as it consolidates under the applied load of tailings or ore, and attenuation of potential contaminants in the process solutions. Synthetic liners can be attributed a finite permeability as a result of minute perforations and seaming deficiencies, and possess none of the above properties. Synthetic liners are also, by their nature, relatively thin and even a small head build-up above the liner will result in a large hydraulic gradient across it.

Jan 1, 1988

By S. C. Sun

Very little information is available concerning the magnetic properties of minerals and only recently has there been any attempt to correlate magnetic susceptibility with varying chemical composition1. The work described here covers a study of the relationship and chemical composition of both the rutile and sphene types of titanium minerals. The relationship between the magnetic susceptibility of three selected mineral specimens and the applied field strength is also presented. Experimental: The equipment and procedures used in this in- vestigation for crushing and cleaning the mineral specimens and for determining the magnetic susceptibilities were the same as that employed by Spokes and Mitchell1. The particle size of-the measured specimens was limited to 270/325 mesh.

Jan 1, 1959

By D. S. Dick

Over the last few years, new methods to characterize the flow properties of bulk solids have been developed. Abrasive wear and particle attrition can now be accurately measured in a laboratory and scaled up to field conditions. In addition, the effect of large particles on a material's flow properties (cohesive strength, bulk density, wall friction) can be determined as well as the effects of various additives such as Freeze Conditioning Agents. New developments have also taken place in terms of devices to improve the reliability of solids flow. Much attention has been paid to finding ways to provide a mass flow pattern with relatively shallow hopper walls through the use of inserts. Such devices can also provide reliable in-bin gravity blending of bulk solids and/or completely non-segregated discharge. Other developments have occurred in the area of belt-to-belt transfer chutes and sealing screws. Many of these developments have direct application in the mining and minerals processing industries. Examples of each will be highlighted.

Jan 1, 1988

By Stanislaw Siewierski

One of the major problems in the exploitation of deep copper ore deposits in the Legnicko-Glogowski Copper Field is ground control and, in particular, roof control of the headings. The depth of copper deposits ranges from 600 to 1200 m. The parameters of ore-bearing rocks and the surrounding rocks show considerable variance of strength properties along the mining thickness (Fig. 1). The roof of the openings exploitation headings consists of dolomite-calciferous rocks. The roof strata consist of layers, the thickness of which vary from several centimeters to 0.6 m (sometimes to 1.0 m). These strata differ in strength and are characterized by igneous and sedimentary discontinuities. On the basis of studies in structure, properties and geological mining conditions of the roof strata in Polish copper mines, the method of roof classification has been developed. (1) This method uses the stability index "L" of the roof, calculated from [ ] The value of "t" ranges from 0, l to 0,8. Based on the value of "L", four classes of the roof (Table 1) corresponding to different degrees of fall hazard have been developed. The mining of copper ore deposit is carried out by a single lift room-and-pillar mining system or a two-stage room-and-pillar system with roof caving. (3, 4). The single lift room-and-pillar mining system is most often used. It consists in working of the deposit of 2.5 to 4.5 m mining thickness, 150-350 m long mining line, consisting of parallel room faces 6 m wide with pillars 5.7 or 16 m wide. As the mining line advances, cross-cuts joining individual rooms are made, thus forming support pillars 3x5, 7x7, 5x16, and 7x16 m (Fig. 2). The two-stage system (Fig. 3) mines the deposit with rooms 6 m wide into blocks 25 x 35 x 25 x 45 m. During the second step these pillars are worked with rooms and cross-cuts into pillars about 3 x 4 to 4 x 5 m (retreat mining). The pillars are crushed just before the fall of the roof. The maximum opening of workings in the two-step system is about 10 m, i.e. one belt entry and one row of bearing pillars. In single lift room-and-pillar systems it is about 35 m., i.e. three belt entries and three rows of bearing pillars. The support of the headings consists of expansion bolts 1.6-1.8 m installed in a bolting pattern 1.1 x 1.5 m. In both systems the fall step is about 10 m, i.e. the width of a belt and a bearing pillar. The Indications of Rock Mass Pressure Individual Dog Heading Individual dog headings are set wide apart from each other in the unmined ore deposit area where there is no interaction of headings. The indication of rock mass pressure are, in such cases, limited to the deformations and damage of side walls. Radiometric studies of rock mass loosening showed that the maximum range of lifts in side-walls immediately after web was 2 m (4,5). In the course of time the cracked side rocks fall off, thus widening the heading. The morphology of side-walls is influenced by the location of the heading in relation to clump layer/tarry. This layer is characterized by a weak strength and "lubricating" properties. The location of the heading in

Jan 1, 1982

By James L. Coburn

Leaching is defined as a form of extraction in which a valuable constituent is removed from a solid body by mass transfer to a solution which, for the purpose of this discussion, is considered to be an aqueous medium. Historically, leaching has been applied to the recovery and purification of many elements. This paper, however, is directed toward the recovery of copper, uranium, vanadium, and precious metals included in the following systems: 1. The leaching of copper minerals, sulfides and oxides, by acid or by ammoniacal leach solutions with or without an oxidant. 2. The leaching of gold and silver, either native metals or as minerals by an oxygen-containing alkaline cyanide solution. 3. The solubilization of certain uranium and vanadium minerals by oxygen or oxidant-bearing lixiviants. Many other systems of this general type exist, but from a production standpoint, these three systems account for most of the major values recovered by leaching.

Jan 1, 1975

By Peter P. Harvey

The Nonel Primadet is a non-electric blasting initiation device. The system incorporates the safety advantages of a cap and fuse system with the precision blasting afforded by electrical blasting caps. Each unit is made up of a delay blasting cap factory-crimped to a Nonel® shock tube lead line. The delay elements in the blasting caps are manufactured in both millisecond and long period series. There are 16 periods available in both series - period 0 through period 15. The units are manufactured in 12', 16', and 20' lead lengths. The hollow shock tube is made of surlyn plastic and it is coated on the inside with a reactive material. The powder train has a density of only 1/10 grain per linear foot of tube. A typical blast round is timed precisely the same way it would be with electrical caps. After the round has been timed and loaded, the tube leads are gathered in convenient bunches and tied into a detonating cord trunkline. The Nonel® tube bunches are initiated by the output of an 18 grain per foot detonating cord trunkline. Once initiated, the Nonel® shock tube will reliably propagate at 1800 meters per second. The energy from this shock front initiates the delay elements in each delay cap. The shock tube is inert to electrical energies, including; stray current from AC/DC power sources, as well as, electrostatic discharges. The tube is also inert to initiation by impact. The system has proven to be particularly advantageous in both tunnel and shaft blasting applications. The major advantages in using the Nonel® system in this type of work are: 1) faster and easier tie-in techniques through the use of bunch-blasting. 2) electrical power can be left on during loading and tying-in. a. electrical lights can be turned on at the working face - better lighting facilitates loading and tying-in. b. electrical pumps can continue to function throughout loading and priming procedures (this is particularly advantageous in shaft work with water problems). 3) down-time due to approaching electrical storms is minimized. 4) increased overall efficiency in the blasting cycle: a. it is easier to train a man in the proper use of the system. b. fewer missed holes per round. c. less time required for tie-in. 5) safety-advantage--The system is not susceptible to involuntary initiation from extraneous electrical energies.

Jan 1, 1979

By Vittorio Manassero, Antonello de Risi, Filippo Cavuoto

"This paper deals with an innovative mechanized method to bore and simultaneously line circular shafts, adopted in the Naples Metro project for the installation of 10 vertical shafts for ventilation purposes. With this method, excavation of shafts is carried out under a positive head of stabilizing fluid by a milling machine, temporarily set at the bottom of a permanent lining made of precast reinforced concrete segment rings. The debris is evacuated by inverse fluid circulation. The shafts in Naples are 4.5 m I.D., from 34 to 44 m deep and they are all located downtown in a highly urbanized area. They were bored and installed into volcanic soils under a hydrostatic head of up to 30 m. Displacements and groundwater level were constantly monitored to keep control of the effects on the surrounding buildings and utilities. INTRODUCTIONThe extension of Metro Line 1 in Naples (Italy) from the previous terminal of Piazza Dante to Piazza Garibaldi is also called the “low stretch”. Most of it runs along the coastline, encompassing the historical city center, the Greek-Roman Neapolis. The Metro Line crosses under densely urbanized areas for the whole way (Figure 1). It runs beneath Via Toledo, which follows the layout of the ancient Aragonese walls. The first station (Toledo) is located halfway along this street. Then, after a wide bend, the line reaches Piazza Municipio, where the second station is located. From there, the line moves along the axis of Via Depretis and Corso Umberto I, where the stations Università and Duomo are situated. The fifth station is in Piazza Garibaldi and the end of the stretch is located at the Naples Business Center. The twin single track tunnels were bored into volcanic tuff by TBM. This design choice simplified by far the construction of the tunnels and reduced to practically zero the interactions between tunnelling and surface buildings and utilities. Nevertheless, this choice entailed that the line had to be located at depths to the order of 35-45m below ground level and 30-35m below the water table. At each tunnel segment between stations, a pair of ventilation chambers were constructed (10 in total). Each ventilation chamber is connected to one TBM tunnel by a vertical shaft and a horizontal drift at the base of the shaft. The shafts, in addition to tunnel ventilation, provide a safety access/escape."

Jan 1, 2016

By M. S. Vernon, J. J. Kellar, W. M. Cross, R. M. Winter, F. J. Johnson, A. G. Pommer

Three substrates (MgO crystal, CaF2 crystal and Mg plate) were used to construct thin layers of Mg(OH)2. Various routes were used to modify these substrates, including surface hydration and sol-gel coating. In each case, it was found (by using Fourier transform infrared spectroscopy) that thin layers of Mg(OH)2 could be produced. In the case of hydrated layers, the surface morphology of the Mg(OH)2 resembles the bulk platelet shape of precipitated Mg(OH)2.

Jan 1, 2000

By Donald T. Delicate

Since the discovery of uranium in the Ambrosia Lake Area in 1955, a new mining district has developed which promises to be the greatest uranium producing area in the United States. Exploration and development work is proceeding rapidly in mines operated by Kermac Nuclear Fuels Corporation, Phillips Petroleum Company, Rio De Oro Uranium Mines, Inc., Calumet & Hecla, Inc., Rare. Metals Corporation, Homestake-Sapin Partners, Homestake-New Mexico Partners, and Centennial Development Company. Individual mining operations vary in size from 200 tons to more than 1200 tons per day with production from wet and dry ore bodies ranging in depth from 300 to 1500 feet. Many problems have been encountered during the development period in the district mines. Within this paper the author will review some of these problems and mining practices being used. In order to understand better the developments to date, a brief description of the area and its geologic setting will be presented.

Jan 1, 1959

By A. C. Noble, D. E. Ranta

Orebodies with intricate three-dimensional shapes (such as porphyry molybdenum deposits) are difficult to model using geostatistics or other computer-assisted methods. The strong trends in their spatial grade distributions occur as mathematically complex shapes and prevent the customary assumption of local stationarity that is required for accurate ore reserve estimation. "Zoned Kriging", a new method developed by AMAX, solves this problem directly by using the geologist's interpretation of the ore zones as a parameter in the kriging equations. The geological basis and methods used in the Climax ore zoning technique are reviewed and discussed relative to their application in zoned geostatistical modeling. The Zoned Kriging technique is described and demonstrated using data typical of mineral deposits.

Jan 1, 1992

By Paul M. Keyser, Donald G. Foot, Jeffrey D. Mckay

In the past 30 years, there have been tremendous advancements in the uses and applications of column flotation. From their first use as final cleaners that could produce excellent grades at the cost of recoveries, columns are now being used in every stage of the flotation circuit as well as is SX-EW. Columns as roughers, final scavengers and even at the end of CIL circuits, are finding their way into the marketplace. Operational results of these new uses are presented. INTRODUCTION Flotation columns have been in use since the early 1950's in the U.S. (Hollingsworth, 1952) and the early 1960's in Canada (Trembley, Boutin, Wheeler, 1963). Application of column flotation has been somewhat diverse. In the early years, columns were used predominately for molybdenum cleaning in Canada and for phosphate flotation in the United States. Unfortunately, results met with skepticism and disdain as the columns were hard to operate, temperamental and although producing high grades, could not achieve acceptable recoveries. Since the inception of column flotation technology, the degree of knowledge for design and operation of columns has vastly improved. Despite improvements in the technology, there is still some reluctance by mineral producers to investigate the use of column flotation cells for processing stages other than cleaner flotation. This characterization is in part due to the proven advantage of flotation columns in reducing gangue entrainment in the froth product which results in higher grade products and/or fewer processing stages. Also, during the development of column technology, different types of spargers have been used with varying degrees of success. Furthermore, the general knowledge base of parameters affecting column flotation design and operation have advanced tremendously. Inefficient, or primitive, sparger design, coupled with the lack of column design and operating knowledge and experience, resulted in poor metallurgical and mechanical performance in many cases. Unfortunately, this lack of knowledge caused many column installations to be characterized as failures. The industry felt that columns could not achieve high recoveries, especially when dealing with coarse particles. Therefore, columns were characterized as cleaners, where low recoveries could be tolerated as recirculating loads rather than direct losses and froth cleaning advantages of the quiescent column flotation regime could be realized. Fortunately for the minerals industry, some producers have stood at the forefront of technology and allowed the column to be utilized for new applications. In the last decade, column flotation applications have expanded to virtually every mineral system and plant location throughout the world. The expanded application of columns has generated a new wave of interest for processing various streams. One of the most notable is in the use of columns as rougher cells. This is of particular interest to "green-field" plants and plants where expansions are taking place. Here, metallurgical superiority can be combined with maximum capital and operating cost advantages for a rapid return on investment. The superior results experienced to date, have generated a cohesive vision of the future in mineral processing where flotation columns function as single stage primary separation devices (roughers) with a single stage cleaner, if necessary. The advantages of column flotation go far beyond their original uses. We now have seen columns used as final tail scavengers, in SX-EW plants and even at the end of CIL circuits. Some of these cases will be reviewed. CASE STUDIES In an attempt to show the diversification of column flotation to many facets of the mineral processing plant, a variety of case studies will be discussed. Some of these were designed by the authors while others have been provided by plant sources. It is important to note that in each successful case, the columns were designed using the author's design and scale-up approach. This method assures that the columns are designed correctly for their particular application. For successful

Jan 1, 1993

By F. F. Aplan

Estimations have been made of the tonnage of raw ores and coal treated by various beneficiation processes. The amount treated by gravity concentration is substantially greater than that treated by flotation, with coal representing the bulk of the material treated by gravity means. A discussion is given of the trends and anticipated improvements in gravity methods. Except for the concentration of iron ores, magnetic and elec- trostatic separation processes find their greatest use in the beneficiation of non-sulfide ores. Exciting new developments in magnetic materials and separation process (and, to a lesser extent, in the electrostatic process) indicate a substantial increase in the application of such processes to ores and a broad variety of non-ore uses.

Jan 1, 1989