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By R. Xiong, A. K. Fallaw, G. Wang, L. R. Moore, S. Dobson, J. Gu

"INTRODUCTION The Central District of the Florida phosphate industry is located in southwest Polk and southeast Hillsborough Counties, with the Southern Extension lying in western Hardee, eastern Manatee and northwest De Soto Counties. (Lawver, 1983) Figure 1 shows the major phosphate formations in Florida. Almost all Florida phosphate production has been in the Central district with additional production from a mine in the Northern District. The Central District is comprised of the Bone Valley Deposit, a relatively thin layer of high grade ore which has been the main source of phosphate mining for decades, and the Hawthorn formation, a thick but low grade formation which covers most of peninsular Florida. (Lawver, 1983) Florida phosphate producers use the Crago process where calcium phosphate is floated with anionic, fatty acid type collectors followed by cationic reverse flotation of silica with amine type collectors. The phosphate matrix is put through various size separation techniques to obtain a typical -28 Mesh (< 700 µm) particle size for fine flotation and a -16 mesh (< 1190 µm) to +28 mesh (> 700 µm) particle size for coarse flotation. In some cases this coarse fraction can be sent to shipping as an intermediate product. The +16 mesh (>1190 µm) to – ¾“ (19 mm) fraction is sent to shipping as a final product called pebble. Figure 2 demonstrates a simplified diagram of the mining and processing of calcium phosphate (matrix) through a Central Florida mine. Particle size and mineralogy are important considerations in the Crago process for two main reasons, the mass of the particle and the particle surface area. Both of which are dependent on the coordination of the anionic collector to available Ca2+ sites on the minerals’ surface. The increased surface area, and available Ca2+, of the smaller apatite particles will allow for more fatty acid molecules to coordinate than the larger particles, with a lower availability of Ca2+. So, the larger particle would require more collector to be introduced in the system to sufficiently cover the apatite particles to produce a surface sufficiently hydrophobic to attach to air bubbles allowing flotation to occur. (Guan, 2009) The Bone Valley deposit has very favorable flotation characteristics when compared to other mining ores around the world. The matrix of the Bone Valley is relatively high grade, BPL (Bone Phosphate in Lime) values typically range from 6-18%, BPL recoveries, from such a matrix, can often be achieved above 85+% with fatty acid based collectors dosed below 1 #/ton. As mentioned, the sizing is an important step as there is also high grade apatite in the +16 mesh (1mm) that is screened to a final product grade, 60-65% BPL. The lack of quartz in the larger size fraction has allowed the Central District to produce high quality, low cost phosphate product, called pebble, through effective screening with no further beneficiation. (Guan, 2009)"

Jan 1, 2015

By L. Galarza

"INTRODUCTION Beneficiation of ores and minerals in a concentrator plant requires a significant amount of water [1] for the grinding and particle separation processes; most of it ends up being recirculated for reuse, slurry pumps are used after crushing and grinding feeding the ore to a classifier to separate fine-grained material (less than 5 mm) from coarse-grained material requiring further grinding. The lower ore grades [2] in the past couple of decades have demanded an increase on power size and efficiency of process machines to maintain a competitive plant throughput; Hydro-cyclone feed pumps to control both under and over milling or grinding are not the exception; Fig. 1 shows a conventional drive train [3] comprising an (1) asynchronous motor (also known as squirrel cage induction motor = SCIM), a high speed coupling (2), a gear reducer (3) and a low speed coupling (4) attached to the shaft of the pump (5), to accommodate the motor rated speed (typically 1800 rpm) to the process requirements (in the range of 250 rpm to 350 rpm), requiring additional components related to the gearbox: instrumentation, maintenance, disposable lubricants and filters, spare parts, thus reduces the overall system efficiency ultimately reflected into CAPEX and OPEX.WHY VARIABLE SPEED DRIVES FOR CYCLONE FEED PUMPS Hydrocyclones or commonly referred as “cyclones” are one of the most important devices in the minerals industry [4]; almost universally used in close-circuit grinding because of their high capacity and relative efficiency, the evolution of Power Electronics made affordable the use of Medium Voltage - Variable Frequency Converters (VFC) for Cyclone Feed pumps in combination with induction motors larger than 500hp (373kW) to gain multiple benefits: - Soft start with minimum electrical utility disturbance = inrush current mitigation - Full Torque available at zero speed for overload startup with pulp solidification after long still stand periods, superior to any other reduced voltage starting method. - Optimum and constant pump speed (independent of the electrical network or load condition), compared to across the line SCIM operation - Flexible Motor Voltage and Speed regardless of the power distribution Voltage and Frequency - Improved Power Factor (close to unitary), over the entire operating speed range"

Jan 1, 2015

By William T. Griswold

Few metals or industrial minerals can boast a better growth record over the past fifteen years than the borates. This period of growth occurred before the influence of any large-scale use in plastics or high-energy fuels. These new developments not only provide expanding markets, but the programs related to their development are generating research information that will lead to many other new uses. The most dynamic growth areas for refined products of boron or borates are in the acid, the oxide and the reduced forms, such as the metal and the hydrides. Expanding requirements for these products will modify the emphasis on the use of naturally occurring sodium borates. Any borate from which boron can be economically extracted will become a potentially important ore. This is particularly true of the calcium borate, colemanite. Only one large deposit in the Western World has ever been developed where the principal economic minerals are sodium borates, This factor alone would discourage any exploration program directed solely toward the discovery of these ores; on the other hand, ample exploration opportunities for calcium borates exist in the desert regions of California and Nevada. It is therefore reasonable to restrict a program to this region, in spite of geologically favorable areas in foreign countries such as Turkey, Argentina and Chile.

Jan 1, 1959

By J. H. Canterford

To date, large-scale solution mining has received little attention in Australia, although the potential of this technique has not gone unnoticed. The possibility of long-term damage to the local environment has also been recognized. Because no two orebodies are the same, it is clear that the application of solution mining techniques and the assessment of environ- mental damage will be somewhat different for different orebodies, even though the general principles will be the same. At present the most significant copper solution mining operation in Australia is at the Mammoth (Gun- powder) Mine in northern Queensland. This mine currently produces more than 3 000 t of cement copper a year.1

Jan 1, 1981

By David J. Hatem

Public-private partnerships (PPP) are gaining in popularity at the federal, state and local levels as the public sector seeks private capital to finance infrastructure and other projects that traditionally have been funded with public funds. In general, a PPP involves a development agreement between a public owner and a private sector concessionaire. Under the development agreement, the concessionaire is responsible for financing, designing, constructing and typically operating and maintaining the completed project for a concession period (often multi-decades in duration). The concessionaire typically enters into an agreement ? the design-build agreement ? with a design-builder to design and construct the project. The concessionaire may secure financing from banks, investors or from a combination of these and other sources (collectively the financier). While the PPP experience in the United States has been modest to date, an increasing number of projects involving tunneling or other significant subsurface work are already being delivered in the PPP mode. Public owners have significant options to address risk allocation for subsurface conditions on PPP projects. The same sound and fundamental principles of fairness in risk allocation that apply in other major subsurface projects should be applied and adopted in the PPP context

Mar 1, 2014

By J. M. Mutmansky

Procedures for the determination of the operating point that results when a fan is connected to a mine and placed in operation have been a source of confusion for decades. A variety of techniques has been proposed, often to the detriment of the practicing ventilation engineer trying to apply the techniques to the multitudinous mine/fan matching problems encountered in the engineering of mine ventilation systems. This paper proposes some different assumptions and definitions that simplify the solution of problems in determining the operating point. As a result, a set of procedures is provided for determining the operating point of a mine/fan system when the outlet areas of the mine and fan are known. To establish a major simplification in the development of procedures for the determination of the operating point for a mine/fan combination, the authors suggest that the mine pressures be redefined and then used in such a manner that the conservation of energy is ensured. This provides the basis for the recommendation that the fan operating point be determined using the fan total pressure and the system total pressure characteristics. This procedure can be applied to fans in the blower, booster, and exhaust positions equally well and to both single-fan and multiple-fan networks. Another advantage is that the method is applicable to fans with or without an evase.

Jan 1, 1984

By C. W. Schultz

The Alabama tar sands of the Hartselle Sandstone formation present a more difficult problem in primary extraction than do the Athabasca tar sands. In contrast to the Athabasca tar sands, the Alabama tar sands are "oil wetted" and the contained tar, or bitumen, is of much higher viscosity. A physical beneficiation scheme was developed in which clean sand from an external source was used as a scrubbing medium. High intensity scrubbing liberated the tars which are readily recovered by froth flotation. Locked cycle tests have shown that, after the use of an initial ration of clean sand, the system produced enough new clean sand to be self sustaining.

Jan 1, 1992

By Michael L. Clar

Reclamation of surface mined lands has two basic objectives: (1) the elimination or abatement of undesirable environmental conditions, and (2) the restoration of mined land to its former or more productive uses. This paper addresses some of the planning concepts and site factors that influence the selection of suitable land uses for surface mined lands. Three planning concepts included in the discussion are: (1) mine land planning, (2) comprehensive land use planning, and (3) environmental site planning. The site factors that will influence the selection of an appropriate land use have been grouped into three categories: (1) legal, (2) geographic, and (3) natural. The natural factors are further subdivided into three groupings: geomorphology, soils, and climate.

Jan 1, 1981

By H. Sevim

An innovative approach in designing the haulage systems for underground coal mines is discussed in this paper. The haulage systems are formed by serially connected components. Therefore an economic and efficient design of the entire system is necessary. The computer model that uses a heuristic algorithm solves this design problem globally in a single run. It is a probabilistic model because it considers the probabilistic aspects of face operations. It is versatile because it can accommodate any type of mining and belt conveyor network configuration. The hoisting section can be used to design drum or friction hoisting systems for single or multiple level operations. These systems can have two skips in balance or a skip and a counterweight in balance. The model also has the option to internally determine the capacity of bunker(s) and shaft-bottom bin. The objective is to minimize the expected cost per ton of coal hauled from the coal faces to the surface. At the end of the paper is an example that illustrated the capabilities of the model.

Jan 1, 1987

By Gerhardt A. Bennewitz

The mechanism shown here (Fig. 1) may not be all that it appears to be. To many of you it may look like a hopper car, a thing of mobility, in which you would ship coal, ores, limestone, or other bulk materials. It is approximately 50 feet long, 12 feet high, and can be placed on tracks which are on approximate 14 foot centers. But far too often in the past, and all too often today, this mechanism has been made to serve as an immobile storage box, with its primary role -- the transportation of products, seemingly incidental to the storage function. Our engineering training teaches us to conserve resources, despite some of the popular and misconceived philosophies being advanced these days. Those of you who work for companies with traffic departments know that they are always striving to reduce the price which is paid to move your mine products. Today, let&apos;s consider and analyze the ways in which the cost of transporting your mine products might be reduced, based on particular reference to coal. Bear in mind that in this context, cost and price are not necessarily synonymous. Until a few years ago, most coal and other bulk materials handled by railroads moved under standard tariff rules. These rules, which still exist today, provided transportation vehicles (railroad cars) for extended periods at no added price to the shipper or receiver. "Normal" free time rules would permit a car to be held for a maximum of 48 hours without charge; however, in the case of coal, there is a rule which, subject to liberal rules as to the

Jan 1, 1972

By O. A. Bascur

The problem of setting the proper control objectives and/or having several objectives to be met in the implementation of grinding control strategies can be resolved. The design and implementation of a distributed control system for safe operation of a grinding circuit while maximizing profit is presented. An optimal recovery/throughput target for a desired grind is accomplished by advanced control strategies at the DCS level. A mill load constraint control technique provides stable operation with a substantial increase in throughput, while the desired grind index is maintained by an inferential grind control technique without using a particle size analyzer. The integration of crushing/grinding and flotation in the overall design was the key to the success of the project. This synergistic effect was obtained by implementing a computer -plant management system in the concentrator. The overall philosophy of keeping the implementation simple but not simpler was used.

Jan 1, 1989

By Joseph M. Keane

A number of innovative techniques exist for solving heap leaching problems in special situations. Some of these techniques have been successfully applied and others await an opportunity for application. Discussions in this paper will deal with gold heap leaching under severe thermal conditions, in tropical rainfall circumstances, in the absence of fresh water, and in other situations removed from the ordinary. CLIMATIC CONSIDERATIONS The success or failure of precious metal dissolution operations may be strongly dependent upon proper attention to the influence of climate. A few examples are given in the following paragraphs.

Jan 1, 1987

By J. Boldy

The discovery of the Delbridge massive sulphide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage halo as a litho-chemical pathfinder to blind ore, coupled to its location relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy. Systematic sampling of micro-fractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulphide deposit was subsequently found to be blind and topped at the 110 metre level.

Jan 1, 1984

By W. R. Ernst

A method for the removal of nickel and vanadium contaminants from spent HDS catalysts involves pretreating the catalyst with H2S followed by the extraction of the metals with an acidic solution of ferric ion. The ferric ion solution alone removes significant amounts of active ingredients cobalt and molybdenum; however, after pretreating the catalyst with H2S, the extraction becomes more selective for the removal of Ni and V.

Jan 1, 1986

By Christopher Newman, Andrew Minckley

With underground stone operations developing in deeper and more geologically complex conditions, accurate pillar stability analysis becomes for the evaluation of engineering design. This paper provides engineering-based recommendations for applying LaModel to evaluate multiple-level room-and-pillar stone mines in both shallow and deep cover. It provides practical guidance on model calibration using field observations, selection of input parameters, and interpretation of results to inform design and operational decisions. The analysis demonstrates LaModel’s effectiveness in simulating pillar load transfer, stress redistribution, and failure mechanisms in complex mining geometries where empirical methods may be inadequate.

Feb 22, 2026

In 1936 a young Dutch geologist discovered an exposed ore mountain in the remote, mountainous province of Irian Jaya, Indonesia. This was the beginning of one of the most overwhelming challenges ever faced in obtaining mineral resources from the earth. The challenge was to traverse mangrove swamps and reach deep into the almost impenetrable jungles of the Jayawijaya Mountains which have an elevation of 4900 meters (16,000 ft.). The target was an almost inaccessible mountain of copper ore.

Jan 1, 1988

By E. Bonates

Truck/shovel systems are a major form of materials handling in open-pit mines in spite of the high associated capital and operating costs. Mine management is usually faced with a decision to purchase new equipment in order to support the steadily increasing on production. These decisions involve a high degree of uncertainty with respect to future demands and technical developments. This paper describes a computer simulation model for evaluating the optimum equipment fleet in an open-pit mining operation. The system is based on a stochastic simulation program which accounts for the various mining and economic parameters. It calculates the type of equipment and the optimal number of trucks needed to meet the production targets. Two types of selection criteria: maximum rate of production or minimum cost can be applied.

Jan 1, 1989

By William Lodding

Unlike most ore minerals, the raw materials for lightweight-aggregate, such as clays and shales are abundant everywhere. In view of this ample choice, what are the reasons for many plant failures attributed to the raw material? How can we arrive at a proper choice of the raw material, the proper processing method for the chosen material, predict its behaviour in a plant and the properties of the final product? Determine the uniformity of the raw material and possible harmful impurities? One basic choice is sintered versus kiln-fired aggregate. It will be based on market preferences and availability of the raw material. Almost in every case a good raw material for one process is poison for the other.

Jan 1, 1964

By Ryan Ward

The Missouri River Intake Screen Structure and Tunnel (MRISST) is one phase of the Red River Valley Water Supply Project (RRVWSP), a vital piece of infrastructure in the state of North Dakota to transport water to drought-laden communities in the eastern half of the state. The scope of work consists of constructing a cofferdam in the Missouri River, mining a 1,600-foot by 74-inch tunnel from a secant pile shaft near the riverbank into a cofferdam, and erecting a 40-foot Y-shaped vertical pipe structure in the cofferdam to support the intake screens. Construction personnel worked in the river through the North Dakota winter to construct the cofferdam and contended with high hydrostatic pressures and raveling sands, gravels, cobbles and boulders while mining the tunnel. Diligent planning and meticulous execution were essential to overcoming the challenges encountered below the Missouri River.

Jun 13, 2023

By Chris Groccia, Damodara R. Chinnasane

Vale is in the process of resuming mining in the lower 810 ore body (810 OB) below 4130L at Copper Cliff Mine – South Side. Production in the lower 810 OB had continued until it was temporarily ceased in 2017 to allow for the execution of activities associated with Copper Cliff Mine Phase 1 project. While mining the stopes in both the lower and mid part of the 810 OB, a seismic response was experienced that resulted in rockbursts and challenging mining conditions. The majority of the rockbursts experienced in the past were associated with stopes mined in a bottom-up mining sequence under a diminishing pillar situation between 3350L and 3540L. The current mining plan is comprised of both top-down and bottom-up mining fronts using a center-out chevron sequence of long hole open stopes to manage induced stresses. Numerical modeling assessments have been carried out to forecast the response of the rock mass due to the planned mining. Seismicity and stress induced damage surrounding excavations are anticipated, and areas requiring extra attention have been identified. A tactical approach is being used to prepare the area for production, including replacement of ground support elements that are damaged or have insufficient residual capacity, and installation of dynamic support in areas anticipated to experience bulking and/or dynamic loading that would exceed the current support system’s capacity. A series of monitoring programs are being put in place to confirm current conditions, and to monitor the response of the rock mass to proactively implement ground control tactics should the need arise. This paper provides a summary of the approach used to forecast, monitor, and manage the behavior of the 810 OB rock mass response to continued mining at depth.

Apr 26, 2022