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By M. Sinirkaya

The dissolution process of phosphate rock from the Semikan area (Mardin-Mazidagi, Turkey) using dilute phosphoric acid has been investigated. The work involved studying the effect of important variables, such as reaction time, stirring speed, particle size fraction, phosphoric acid concentration and temperature. Van der Sluis et al.?s model was used to determine the rate of the partial dissolution of phosphate ore. Mass-transfer coefficients (kL) varied between 2.8 and 28.5.10-3 m.s-1. The activation energy of the process varied between 16 and 20 kJ.mol-1. It has been found that the dissolution process is controlled by calcium ion diffusion, rather than by chemical reaction.

Jan 1, 2010

Drainage and erosion control often become problems at mine reclamation projects. An example of this was an abandoned surface uranium mine on the south Texas plains. Engineers with the Texas Railroad Commission solved these and other problems with a three-dimensional geomatrix erosion-control matting at the 69-hm2 (170-acre) site, about 70 km (45 miles) southeast of San Antonio. Enkamat, manufactured by Akzo Nobel Geosynthetics, was installed to reinforce the grass waterways that handle runoff from the reclaimed mine. Reclamation was completed in the spring of 1992. Bill Walker is regional manager for Erosion Control Systems. He worked with the contractor to identify an erosion control product that complied with the project's design and installation parameters. "Use of erosion control matting enabled us to reduce erosion control costs," said Mark Rhodes, with the Texas Railroad Commission. "Also, the erosion control material was more aesthetically compatible with the reclaimed landscape." The commission's design called for a terrace ditch to be constructed midway up the reclaimed spoil slope to catch and collect water. Commission engineers selected spoil slopes, ranging from 5% to 8%, to build reinforced grassed waterways to drain the collected water from the terrace ditches. This was done instead of dropping the water at steeper slope location in rip rap- or concrete-lined channels. Enkamat's three-dimensional geomatrix of heavy nylon monofilaments is 95% open space that aids root growth. Its root-reinforcement system resists the hydraulic lift-and-shear forces created by high-volume discharges of water. In addition, fine eddy turbulences are prevented from isolating and uprooting individual roots and clumps of vegetation. Enkamat is flexible and lightweight. This makes it easy to install. And, because grass grows into it over time, it "disappears" after installation. Between 12,540 and 14,200 m2 (15,000 and 17,000 sq yds) were installed in the waterway using 150-mm (6-in.) staples to fasten the matting, said contractor Dale Blackstock. "It was easy to use; no problem at all to put down." Blackstock selected Enkamat from a list of eight different channel lining materials described as acceptable in the commission's design specifications. The design specifications were based on the results of channel-lining performance tests conducted by the Texas Department of Transportation. Rhodes said that the commission's Abandoned Mine Land Reclamation program had installed Enkamat on other abandoned uranium mines and on an abandoned surface lignite mine near Austin. "Pretty much all of our installations of Enkamat have worked out well," he said. "There have been no failures. The reinforced grass waterways have performed as designed."

Jan 1, 1998

By P. Mousset-Jones, F. Calizaya

Currently, a 4.3 km long drift is being developed on the 3440 level in the Lower Kalamazoo project at the San Manuel Mine, Magma Copper Company, AZ. The drift, located at 1050 m below surface, is being constructed using a 4.6 m diameter tunnel boring machine (TBM). The drift is ventilated by a forcing type auxiliary ventilation system. At the face, to mitigate the impact on the work environment of the TBM, the system is equipped with dust extraction and refrigeration systems. Recently, to evaluate the ventilation conditions in the drift, a continuous monitoring system has been installed. The system can be used to measure the air velocity, barometric pressure, relative humidity and air and rock temperatures. This study describes the capabilities and limitations of this system, and presents a summary of the results.

Jan 1, 1995

By G. Adel, J. M. Richardson

Mine-to-mill optimization is a holistic approach to the optimization of mining and processing operations. Developed at the Julius Kruttschnitt Mineral Research Centre, it attempts to minimize energy consumption through the optimization of the particle size reduction process. The approach involves sampling and modeling of blasting and processing, computer simulation to optimize the operation and develop alternatives, implementation of the most promising alternatives, and sampling to quantify energy savings. The primary objective of the present effort is to adapt mine-to-mill technology to the aggregates industry. This paper presents an update of work being conducted at quarries operated by the Luck Stone Corporation of Richmond, Virginia.

Jan 1, 2006

By H. EI-shall

In this paper, the results of bench scale testing of five different flotation processes to separate dolomite from phosphate are discussed. The effectiveness of each process interms of phosphate recovery and MgO content in the concentrate is used together with the reagent consumption as the basis of comparison. The water quality is found to play a major role in the performance of these processes. Effect of water hardness as well as other parameters are discussed.

Jan 1, 1995

By A. R. Laplante

A test to determine the amount of gravity recoverable gold (GRG) in an ore is described. Typical GRG results are given; an error analysis is detailed; possible uses are discussed. Of the 38 samples tested, the lowest GRG content was found to be 25% (most below 25 11m, or 600 mesh), and the highest 94% (most above 300 11m, or 50 mesh). The average GRG content was 63%, with a standard deviation of 19%. Error analysis shows the test to be reproducible within 5 to 10%, depending on the size distribution and grade of GRG, and the sample extraction protocol. When using the same primary sample, reproducibility improves, 2 to 5%, depending on the amount of gold coarser than 850 11m (20 mesh) and sample weight. The test has been applied to greenfield project and retrofit applications, to determine the suitability of gravity recovery. For existing circuits, it has been coupled with a model of gravity recovery for optimization studies.

Jan 1, 1996

By Peter L. Dunn

With the advent of new high-strength magnetic materials, rare-earth magnetic separators have become more common place for processing heavy mineral sands. In many instances, rare-earth magnets have replaced conventional separators such as electromagnetic cross-belt and induced-roll type machines. This paper will present the results from a detailed test program developed to evaluate the performance of rare-earth drum and roll separators for processing heavy mineral sands. The effect of machine design parameters, such as magnetic element configuration and separator diameter, will be reviewed in light of these test results. The impact of basic operating parameters (i.e. feed rate and roll speed) on separation efficiency will also be presented.

Jan 1, 1999

By J. B. Malcolm

The discovery of tungsten-bearing quartz outcroppings in Vance County, N. C., by the Hamme brothers in 1942, made international news in the mining industry and was, in fact, one of the major ore discoveries made in the U.S. during the last 25 years. Operations began at the Hamme mine in 1942, but after 16 years of successful operation, the mine was closed down in 1958 under adverse market conditions. By that time, it had produced nearly 20 million lbs of metallic tungsten. Because of the square-set timber mining method then in use, mine operating expenses were high, actually representing 78% of the total operating expenses at the property. In timber work alone, 160 men were employed. Approximately 500,000 bd ft of timber were placed monthly at a direct supply cost of $1.00 per ton of ore mined. Late in 1959, following a slightly improved position in the tungsten market, company management decided that, by changing the mining method, the operation could be economically feasible. The major premise in this decision was that a reduction of from 25 to 30% of the mining costs could be achieved by the conversion of the mining method from square-sets to horizontal cut and fill. Reopening of the mine began in February 1960, Full production has now been reached and overall mine productivity has been doubled.

Jan 1, 1962

Impala Platinum?s No.16 Shaft mine is currently under construction and is expected to reach full production of 256 500 tons per month by 2014. Mining will start at 1 260 m below surface with a maximum mining depth of 1 535 m where virgin rock temperatures of 56.6°C will be experienced. As a result of depth, high virgin rock temperature and narrow reef mining, an expected total of 31.5 MW[R] of air cooling capacity will be required to achieve acceptable underground conditions. This will be achieved by cooling mine intake air in a single dedicated air cooling installation located on surface. The compact installation includes air cooling spray chamber, refrigeration machines, condenser cooling towers, evaporator and condenser water reticulation as well as all electrical and control systems. Construction and commissioning of the first phase of this air cooling installation has recently been completed on a turn-key contract basis.

Jan 1, 2009

By Peter V. Avotins

During last year's AIME meeting in New Orleans, Deepak Malhotra and I were discussing some of the topics that would be presented in this Symposium. It seemed appropriate that along with papers on specific reagent and flocculant types, we should address research management aspects of new product development. This development is a long, arduous task that requires a significant technical and fiscal commitment by the chemical company and potential users. A flow chart depicting the research process is shown in Figure 1. The sequence of events are plotted on an undefined time line. Our experience has shown that it takes 3-5 years to complete a typical reagent development project. A new project starts with an idea of how to do something better. The ideas range from relatively simple product modifications to opportunities created by technological change. An example of this is the use of flocculants in tailings operations to close the water recycle loop. The change was brought about by the need to conserve water and comply with environmental statutes. The result was the development and wide-spread use of synthetic polymers to help in solid-liquid separation. More recently the ups and downs of oil prices have led to development of coal water slurries as an alternative to fuel oil. The slurries contain high levels of chemicals (up to 3%) to insure proper stability and burn characteristics. There are technical changes under way right now that may lead to ideas for other new products. One exciting source of new technology is the ability to manipulate genetic material of microbes to select for specific capabilities. This has evolved by leaps and bounds over the past 5 years. Biologically assisted leaching and removal of wastewater impurities are two possible end uses. I'm sure that there are many others. The ideas can originate anywhere and are often half-baked at first, but to lead to new products they must be refined to provide project definition and eventually a research plan. A chemical ,development project cannot be started without approval to commit the company's resources. The internal selling job is often very difficult. The company must see clear financial benefits in order to launch efforts that may not pay off for many years. It is critical to project the total market, profitability, eventual market share, and timing of introduction of the new product. There is much uncertainty in this and the research manager is often skating on thin ice to retain his credibility. Once we obtain support from upper management, the research team is assembled to start the project. The teams generally consist of organic chemists, research metallurgists, and technicians. They have access to analytical scientists and technicians for surface and analytical chemistry. The projects are often augmented by help from university staff and consultants. This is particularly true where there is a need to develop fundamental understanding of the technology in addition to synthesis of chemicals. The project now proceeds along two lines. First, there is an emphasis on understanding the prior art. Extensive literature and patent searches are undertaken to provide research leads and to keep from "reinventing the wheel" and infringing on someone else's patent. The scientists and technologists are qualified to conduct computer-assisted library searches. This process usually uncovers 80-90% of the relevant information. The remainder is very much harder to get and requires the help of professional library search staff with scientific backgrounds. Along with literature searching, the team begins synthesis of new compounds. These are screened by use of techniques such as microflotation or filtration in a Buchner funnel. The scientists are looking for the direction of response as they modify structural features . Inevitably, a large number of candidates reach the next stage, a laboratory bench test. At this point it is possible to set up a research plan and use project management techniques to monitor progress. The bench tests are conducted in larger equipment, usually requiring 100-1000 grams of test substrate. Typical laboratory flotation tests are run in Denver or Wemco cells.

Jan 1, 1986

By D. M. Neil

Road-headers are one of the most popular mechanized excavators used in mining and civil under-ground construction. These machines are primarily used in soft to medium hard rocks. This paper reviews the parameters associated with the application and operation of road-headers and presents a method for estimating cutting performance.

Jan 1, 1994

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

Caterpillar and Fortescue Metals Group have moved forward with the delivery, installation and support of a complete Cat MineStar System at Fortescue?s Solomon iron ore mine in the Pilbara region of Western Australia. The complete technology suite was implemented for the first phase of Solomon, the 20 Mt/a (22 million stpy) Firetail manned mine, in October 2012. As part of an autonomous mining solution for phase two, the 40-Mt/a (44-million stpy) Kings Mine, eight Command for hauling Cat 793F CMD trucks were commissioned and commenced operations in the second quarter of 2013. The mine plan calls for a progressive ramp up to 45 autonomous trucks during the next several years. In addition, other Cat MineStar System capability sets, Fleet, Terrain, Detect and Health, are being used across the mobile equipment fleet, including support equipment and light vehicles. Working closely with Fortescue and its mining contractor, Leighton Contractors, Caterpillar and the Cat dealer in Western Australia, WesTrac, are providing a full solution for managing, operating and supporting Cat MineStar System and Command for hauling. The greenfield Solomon Mine has brought together the skilled team from Caterpillar, Fortescue, Leighton Contractors and WesTrac to deliver an efficient, cost effective autonomous mining solution.

Nov 1, 2013

The prediction and control of ground deformations due to underground mining are important considerations in the permitting, planning, and monitoring of coal mining operations. The prediction of mining-induced ground movements using the influence function method is a mature technology and is widely used in many coal basins around the world. Such movements mainly include subsidence, horizontal displacement, and horizontal and/or ground strain. Predictions can be accomplished using regional subsidence parameters and site-specific data.

Jan 7, 2020

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 S. Sunkavalli

Acid rock drainage (ARD) is produced when sulfides are exposed to oxygen and water. Oxidation reactions typically result in a depression of pH and leaching of solutes and metals. Many oxidation models have been developed based on oxygen diffusion, but in environments with high permeability, other transport processes (i.e., convection and advection) can play an important role. Multiple sulfide mineral phases with differing oxidation rates should also be incorporated. WROC, a finite-difference model, was developed to account for these factors in predicting ARD. The program includes sulfide mineral oxidation using a shrinking core mechanism, heat transfer by conduction, heat of reaction, and oxygen transport by diffusion and advection. The model was validated using data from the literature. After validation, the WROC model was used to simulate several different waste rock scenarios including different forms of sulfide mineralization and the effect of implementing a waste rock cover. The results demonstrate that including specific sulfide mineral phases can have a significant effect on oxidation and that implementation of a cover can also aid in reducing waste rock oxidation. Key words: Arsenic sulfides, oxidation, shrinking core, waste rock, oxygen transport

Feb 27, 2013

By S. E. Phillipson

The Mine Safety and Health Administration?s (MSHA) Roof Control Division (RCD) collects a variety of geological and engineering information pertaining to mining conditions in surface and underground mines throughout the United States. Recently, lineament analyses, trends of geologic structures, and inferred stress directions based on mapping at mines with problematic ground conditions, have been integrated into a GIS. The incorporation of different kinds of information into the same geographic coordinates and map projection, placed on digital geologic maps, allows site specific data to be evaluated in a regional geospatial context, identifying trends in the orientation of horizontal stress or patterns of structural geologic features. As more information is collected, the GIS will evolve as a tool for district- and basin-wide evaluations of controls on ground instability, and may evolve into a predictive tool for some kinds of geologic hazards. In addition to the geologic and geotechnical evaluations, the GIS also serves as a searchable database of previous mine investigations. The database can be searched for a variety of criteria, and the results displayed in real geographic coordinates to find the locations of previously visited mines or to evaluate mine fatality and injury data. This not only allows old reports to be found, but also places the information in a geospatial context with respect to neighboring mines or geographic areas. The GIS also has the capability to serve as a digital mine map repository, where maps can be stored in digital, georeferenced format for display in relation to each other and various themes of interest. This allows evaluation of multiple seam mining interactions and proximity to other mines, and on a national level could serve as an abandoned mine map database.

Jan 1, 2008

By Mohammad Djavid

The one-pass tunneling pipe jacking method has often been the most schedule and cost efficient method for the pipe line installation. The main challenges in jacking pipes larger than 108 inches and for longer runs are: transportation and logistics, requiring high jacking forces, keeping line and grades, control of ground surface settlement, providing adequate external lubrication, and the potential of damaging the joints and pipe spigots. In recent years, 144" diameter pipes have been jacked for short runs of up to only 300 feet. In this article design and construction of installation of up to 1,000 linear feet run of 144-inch internal diameter, reinforced concrete pipes without intermediate jacking station in Chicago O?Hare International Airport are discussed. The article also presents discussions regarding the subsurface saturated silt formation, shallow cover, dewatering, jacking and receiving shafts, jacking forces, lubrication and settlement data.

Jan 1, 2008

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 Mikko Ruonala, Pertti Lamberg, Olli Hyvärinen

The smelting of copper sulphide concentrate is the dominant route in copper production (Figure 1). Heap leaching of oxidized copper ores with weak sulphuric acid together with copper solvent extraction and electrowinning has gained popularity during recent decades, and it accounts for close to 20 % of primary copper production. Heap leaching offers advantages such as lower costs and consequently the construction of a production plant at a mine site is made possible. Limited resources of oxidized copper ores, the long leaching time of chalcopyrite and inability to recover gold inhibit this growth. The HydroCopperTM process developed by Outokumpu Technology at the laboratories of Outokumpu Research, Pori, Finland, is a new chloride leaching technology /1,2/, which offers an alternative to smelting and heap leaching (Figure 1). In the HydroCopperTM process sulphidic concentrates with various mineralogy and grade can be treated at the mine site to produce high-quality copper. Instead of copper cathodes the HydroCopperTM end products are copper wire rod, copper bars or copper billets. One of the advantages of HydroCopperTM technology is that gold can also be recovered in the process simultaneously /3/. To confirm the functioning of the new process and to dimension equipment Outokumpu Technology built the HydroCopperTM demonstration plant in Pori, Finland /4/. It has a capacity of 1 metric ton of copper per day. After testing with Pyhäsalmi copper concentrate in 2003, the first commercial demonstration run with Erdenet copper concentrate took place in 2004.

Jan 1, 2005