Search Documents

By D. Antonov

The physical and mechanical properties of coal play a important role in the planing and design of coal mines. However, due to the complexity conditions in situ and the influence of unknown factors, it is hard for people to evaluate the physical and mechanical properties of coal directly. In this research, uniaxial compressive stress was used to change the attribute of coal samples, and the ultrasonic measure technique was used to evaluate the physical and mechanical properties of coal. The results of laboratory test showed that there was a strong relation between uniaxial stress and velocity of ultrasonic wave. Sensitivity analysis with numerical simulation was used to define the relation between the physical-mechanical parameters of coal and ultrasonoc wave. With the dynamic analysis module of FLAC, three elastic and plastic models were built to model the coal samples. The modeling parameters were changed pro rata, and the correlation of coal and ultrasonic wave properties were summarized and presented. The result from this research will be base for further analysis of caving behavior of coal.

Jan 1, 2010

By D. Puckett

The feasibility of maintaining equipment location, personnel location and vital statistics in surface and underground mining operations has increased with advances in radio frequency identification (RFID) technology. The paper addresses the use of this technology, relatively new in the mining industry, to track surface equipment in mine pits, loading points, and processing facilities. Specific applications are discussed including a simplified and a complex truck tracking system and an automatic pit ticket system. The paper concludes with a discussion of the future possibilities of RFID technology in mining, such as monitoring biofeedback of personnel (heart and respiration rate, body temperature, exertion level, etc.) repetitious movements to study work habits, and logging air quality via personnel sensors.

Jan 1, 1996

By Chester A. Rowland, David M. Kjos

INTRODUCTION Mineral ore comminution is generally a feed preparation step for subsequent processing stages. Grinding, the fine product phase of comminution, requires a large capital investment and frequently is the area of maximum usage of power and wear resistant materials. Grinding is most frequently done in rotating drums utilizing loose grinding media, lifted by the rotation of the drum, to break the ores in various combinations of impact, attrition and abrasion to produce the specified product. Grinding media can be the ore itself (autogenous grinding - primary and secondary), natural or manufactured nonmetallic media (pebble milling) or manufactured metallic media - steel rods, steel or iron balls, or a combination of autogenous media and steel balls (SAG milling). This chapter covers rod and ball mills utilizing manufactured metallic grinding media. MILL DESIGN The interior surface of rod and ball mills exposed to pulp and/or grinding media are protected from wear and corrosion by rubber, metallic or a combination of rubber and metallic wear resistant materials. Rod and ball mills essentially draw constant power, thus are well suited for use of synchronous motors with power factor correction capabilities as drive motors. A net of approximately 120 to 130 percent of running torque is required to cascade the charge in these mills. The pull-in torque is about 130 to 140 percent with the pullout torque to keep the motor in-step (in-phase) generally in excess of 150 percent. When rod and ball mill are started across-the-line the starting and pull-in torques result in inrush currents exceeding 600 percent which possibly result in high voltage drops. To deliver 130 percent starting torque to the mill the motor design must take into account the maximum anticipated voltage drop. Motor torque decreases as the decimal fraction of the voltage available squared. E.g., a motor rated 160% starting torque with a 10% system voltage drop will deliver 160% x or 129.6% torque to its output shaft When it is not possible or practical to start a fully loaded synchronous motor across-the-line it is possible to utilize the motor's pull- out torque to start the mill. By using a clutch, normally an air clutch. between the motor and the mill, the motor is brought up to synchronous speed before the clutch is energized. If the motor has an adequate amount (175 or greater) of pull-out torque the pull-out torque starts the mill without major disruptions on the electrical system. Since the energy release at initial cascade of the mill charge is an inverse function of acceleration time, a minimum acceleration time of 6 to 10 seconds or more is recommended to prevent damage to the mill or the mill foundation. Economics at the time of plant design and mill purchase determine the drive to be used. The simpliest drive is the low speed synchronous motor with speeds in the range of 150 to 250 RPM connected to the mill pinionshaft by either an air clutch or flexible coupling. Using a speed reducer between the motor and pinionshaft permits using motors having speeds in the range of 600 to 1000 RPM. In this speed range, if power factor correction is not required induction motors can be used; squirrel cage where there is no restriction on inrush current; slip ring where a slow start and low inrush current is required. Air clutches can also be used to ease starting problems with squirrel cage motors. In some areas of the world induction motors and starters are less expensive than synchronous motors at a sacrifice of motor efficiency and power factor correction. Dual drives, that is two pinions driving one gear mounted on the mill, become economical for ball mills drawing more than 3500 to 4000 horsepower (2600 to 3000 kilowatts). Further developments of the low frequency, low speed synchronous motors with the rotor mounted on the mill shell or an extension of one of the mill trunnions could improve the cost picture for these "gearless drives", making them practical for large ball mills. The percent of critical speed, which is the speed at which the centrifugal force is sufficiently large to cause a small particle to ad- here to the shell liners for the full revolution of the mill is given in mill specifications. Critical speed is determined from the following: Where D is mill diameter inside liners (specified in meters). Cs is critical speed in RPM. When D is specified in feet

Jan 1, 1998

By I. H. Warren

Hydrometallurgy has a well-known and established role in the production of manganese metal (1) and manganese compounds, including battery grade manganese dioxide (2). Also, several leaching processes have been developed and applied at various times for the recovery of manganese from low grade ores (3). Recently, interest in the hydrometallurgy of manganese has been stimulated by the problems presented in the processing of sea nodules (4). Fumes and dusts from the ferro-manganese furnaces also offer a potential field for the application of manganese leaching techniques (5). In treating low grade manganese ores a major requirement of the leaching process is that it should dissolve manganese from a mixture of manganese and iron oxides. The most selective reagent for this purpose is ammonium carbamate applied after preliminary pyrometallurgical reduction of the ore (6). Since soluble carbamate complexes of the postulated type (7) are formed by both manganous and ferrous, but by neither manganic nor ferric, ions, selectivety of manganese leaching is achieved by control of the reduction operation to yield, essentially MnO and Fe304? A potential improvement to this two step process would be to simultaneously reduce and selectively leach the manganese in one hydrometallurgical operation. This possibility has been experimentally studied and the results are described below. During the preliminary study of the stability of solutions of ammonium, ferrous and manganous carbamates at elevated temperatures, it was observed, contrary to the observation of Welsh (8) at lower temperatures, that

Jan 1, 1971

By Bruce E. Nesbitt, Paul G. Lhotka

At Lupin mine gold is spatially and genetically linked to zones of hydrothermal alteration in iron-formation which are symmetrically developed adjacent to late Archean quartz veins. Immediately adjacent to the veins, coarse grained, typically gold- and sulfide-poor, calc-silicate rocks are often present. These rocks comprise hedenbergite + quartz ± grossular garnet ± epidote ± scheelite ± calcite. Sulfides (pyrrhotite, arsenopyrite and loellingite) and gold are concentrated in the next zone and occur with hornblende-rich rocks comprised of hornblende, quartz, hedenbergite and grunerite. Furthest from the veins are gold- and sulfide-poor, grunerite-rich iron formation comprising grunerite, quartz, hornblende and sometimes magnetite. Although the alteration assemblages have similarities with skarns, they develop in iron formation, and are at best indirectly related to intrusive igneous rocks. Geological and geochemical data clearly indicate the calc-silicate rocks are metasomatic in origin.

Jan 1, 1990

By David A. Grisafe

Divided opinions concerning dredging-permit locations and boating uses on the Kansas River in northeastern Kansas led to a study of the recreation potential on the river by a legislatively mandated interagency group (five agencies) that included the Kansas Geological Survey (KGS). In addition, the KGS conducted its own study of the river corridor, encompassing the development, geology, and economic resources of the corridor (Brady and others, 1998). The corridor area is 12 mi wide and 140 mi long (171 river miles). Included in the study was the potential impact of restric¬tions to river dredging. The Kansas River and its floodplain in northeastern Kansas are underlain by Lower Permian and Upper Pennsylvanian limestones and shales. The river and its floodplain are the major sources of sand and gravel for northeastern Kansas, and the limestones along the river bluffs supply crushed stone and building stone. The population of the 10-county area bordering the river has grown by 20% since 1980, and now comprises nearly 40% of the state's population (U.S. Bureau of the Census, 1996). Projections (Floerchinger, 1992) indicate close to 50% of the Kansas population will reside in these counties by 2025, with a continued increase in the demand for aggregates. Factors such as floodplain width, price and availability of land, and overburden ratios tend to favor river dredging on the lower part of the river, and floodplain or pit dredging on the upper portion. The use of alternate sources of sand and gravel such as the Missouri and Arkansas Rivers would increase sand prices due to transportation costs to much of the 10-county area. In 1996, river and pit dredges along the Kansas River supplied more than 3 million tons of sand and gravel valued at about $8 million to northeastern Kansas. As a result of its study, the KGS had concerns with the idea of large recreation zones on the river that excluded river dredging in areas of presently large population and projected population growth. This controversial issue is likely to recur elsewhere.

Jan 1, 1999

By R. W. Smith, D. L. Taylor, K. A. Altman

The importance of metallurgical information in reaching appropriate decisions during the development of mining projects is demonstrated. A financial analysis is calculated using discrete system simulation. The results are compared to the results of a traditional sensitivity analysis. The traditional analysis is shown to have the potential to overestimate the value of mining projects. The type of statistical distribution used in a random number generator affects the results significantly. The statistical method of analysis provides insight into the amount of metallurgical testing needed and provides verification of how representative the samples are.

Jan 1, 2002

By Ande&apos, Bengt n

The first Model 480 SALA-HGMS R carousel high gradient magnetic separator was recently manufactured (Figure 1). The carousel's design was based upon the high gradient magnetic separation technology developed and owned by Sala Magnetics Incorporated, Cambridge, Massachusetts. After a short (approximately 300 hours) in-house mechanical and electrical test and break-in period, the carousel was ready for a long term demonstration test. This paper describes the demonstration plant and operational performance of the Model 480 HGMS treating a low grade iron ore tailings. A location convenient to Sala International's main office in Sala, Sweden was desirable because Sala engineers and technicians were to operate the demonstration plant. The Strassa iron ore mine in central Sweden was chosen because it fit most of the criteria that was important for a good demonstration site. The Strassa mine is part of the state owned Svenskt Stal AB. The mine produces about 320,000 tons of iron concentrate per year consisting of 200,000 tons of magnitite concentrate and 120,000 tons of hematite concentrate.

Jan 1, 1980

By Michael M. Kimberley

Stratiform uranium deposits occur in Canada along the north shore of Lake Huron near the base of the Middle Precambrian Huronian Supergroup. Outcrop of the Buronian Supergroup extends for over 400 km from Sault Ste. Marie in the west eastward through Sudbury and then northeastward to Cobalt. Maximum stratigraphic thickness exceeds 5 km. The predominant Huronian rock type is metamorphosed sandstone (quartzite), with sub- ordinate argillite, conglomerate, mixtite (possibly tillite), volcanic rocks, and minor limestone, Much of the quartzite is highly feldspathic. Substantial uranium ore was first discovered in Huronian rocks in 1953 and has been exploited continuously since the initial mine-mill plant was constructed at the Pronto ore body, 30 km south of the present townsite of Elliot Lake. Only one ore body remains in production, however. It is shared by Rio Algom and Denison Mines 14 km north of the town of Elliot Lake.

Jan 1, 1980

By Jack J. K. Daemen

A wide variety of subsidence prediction methods exist. They can be classified into empirical methods and mechanistic models. The empirical methods include profile functions and influence functions (Brzuner, 1973a,b; Kratzsch, 1974; Berry, 1978; Hood et al., 1981), the two empirical approaches of most practical value, if only be- cause they are readily programmed on calculators or computers. The profile functions have the advantage that they allow for ready determination of the necessary empirical parameters from field observations. They have the disadvantage of being restricted to subsidence calculations at a very limited number of points or lines above very simple (rectangular) mine geometries. This reduces greatly their practical applicability for damage predictions, which usually require estimates of strains, slopes or curvatures at structures that have arbitrary position and orientation with respect to planned mine excavations. Influence functions can be used to calculate subsidence at any point near an excavation of any in- seam outline. The main difficulty associated with empirical influence functions is the lack of uniqueness in the relation between subsidence and its cause, the convergence distribution over a mined excavation and its immediate surroundings. A secondary practical difficulty is the need for fairly arbitrary adjustments near the excavation edges, usually in the form of compensation zones (e.g. Brsuner, 1973; Hood et al., 1981). Determination of the appropriate empirical constants in influence functions is facilitated greatly when a direct mathematical connection exists between influence and profile function (several examples are given by Brauner, 1973 and by Hood et al., 1981), so that field data can be used to determine the parameters through backfitting of the profile functions, which is considerably simpler and more direct than backfitting of influence functions.

Jan 1, 1982

By D. W. Horsfall

The washability of South African coals is described and the problems encountered in washing at low densities, to make premium products, are enumerated. The measures taken to overcome those problems, when low density separations became a commercial necessity, are described in detail. The descriptions of processes are with specific reference to the three sizes commonly treated separately in coal preparation namely coarse coal, small coal, and fine coal. Some information is given on the performance characteristics of the plants erected to meet market requirements.

Jan 1, 1995

By Gordon B. French, Donald E. Garrett

INTRODUCTION Crude oil reserves in the United States are still very large, even though for many years they have not been sufficient to supply our entire domestic requirements. They are continuously being depleted as oil is pumped from the ground, but new discoveries and improved secondary and tertiary recovery methods are helping to reduce the rate of depletion. It is thus a slowly diminishing resource, but even as it is being consumed, immense reserves of oil are left behind as the so called "un-recoverable" portion of petroleum formations. Most oil fields can only obtain a 15 to 40% recovery of the original reservoir, and it is widely quoted that there are still about 300 billion barrels of this un-recoverable oil still in place (Mauch, 1980, etc.). With the present comparatively high oil prices, and the possibility of even higher future prices and short supply, this oil becomes an interesting potential reserve. Mining the petroleum formation would be one means of recovering at least a portion of this oil. The concept of oil mining is neither new nor limited to conventional oil fields, since the procedure could be equally employed with the otherwise difficult to produce heavy oil deposits, and the solid or semi-solid tar sands and diatomaceous hydrocarbon formations. Estimates place the U.S. tar sand resource at about 30 billion barrels, and heavy oil at 5-10 billion barrels (Unitar, 1982). Figure 1 graphically summarizes the heavy oil reserves based upon formation depth and characteristics, while Figure 2 shows their location. It is apparent that the preponderance of reserves are in California and Texas, but that they also occur in many other states. The major companies engaged in oil recovery from the heavy

Jan 1, 1983

By Joel D. Hammond

Lightweight concretes date back to before the Roman Empire. The earlier concretes were made by combining a burnt lime for cementious material with pumice or volcanic rock for aggregate. Although structural value was limited due to its primitive nature, many structures were able to withstand the test of time. The rotary kiln expanded shale industry had a slow start that began around 1908. The industry was founded by Stephen J. Hayde of Kansas city, Missouri. Mr. Hayde noticed that the bloating effects of some aggregates were undesirable by the brick industry. Material of this type was considered waste and avoided in brick production, but he realized it had all the qualities and basic requirements for a concrete aggregate that would reduce weight and still retain structural value. It came into national attention by use in ocean-going vessels through a shipbuilding program undertaken by the united states Fleet Corporation. This research was brought about by the need to find a suitable material to replace high-grade plate steel due to a shortage created by World War I. The need prompted the government to supply the reserves that Stephen Hayde desired to continue and complete research into producing a uniform lightweight aggregate. His results pointed to the rotary kiln method for which he was granted a patent in 1918. One of the most famous and largest concrete ships built through this program was the U.S.S. Selma. Although the Selma

Jan 1, 1977

By Arthur Darby

The city of Kuala Lumpur was founded in 1857 by miners seeking tin near the confluence of the Klang and Gombak rivers. The rapid development of the city and surrounding area since independence has led to more rapid runoff during rainstorms and to gradual canalisation of the rivers with some restricted sections. The outcome has been more frequent and more severe floods (Abdullah 2006). At the same time the centre of Kuala Lumpur has become a modern inter-national city with tall office buildings, hotels, and shopping centres connected by a network of wide roads and commuter rail systems. With these the cost of dislocation during floods has risen as has the cost of making good damage afterwards. The Government of Malaysia considered these consequences unacceptable and sought ideas from the private sector for a solution. Potential solutions consisted of variations on the themes of bypassing the city centre with a flood relief tunnel or of providing off channel storage or a combination of both. Since under Malaysian law a tunnel cannot be constructed under private property unless this is first purchased or agreement reached with the owner, it was necessary for most of the tunnel alignment to run below existing heavily congested roads. After considering these facts Gamuda Berhad and MMC Berhad, two leading Malaysian development and construction companies, decided to propose to Government an innovative solution in which the tunnel would be used to carry road traffic except during floods.

Jan 1, 2008

By T. F. Dumm

With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink-float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and sub-sieve particle size analysis of the specific gravity fractions, a complete size-specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.

Jan 1, 1987

By W. B. Lambert

A common decision in openpit mining is to determine the extraction sequence of notional three-dimensional production blocks so as to maximize the net present value of the extracted orebody, while adhering to precedence and operational resource constraints. This openpit block sequencing (OPBS) problem is commonly formulated as an integer program, with binary variables representing if and when each block is extracted. In practical applications, the number of blocks can be large and the time horizon can be long; therefore, instances of this problem can be difficult to solve using the exact approach of optimization. The problem is even more challenging to solve when it includes explicit minimum operational resource constraints. Our maximum value feasible pit (MVFP) algorithm generates an initial integer feasible solution for OPBS problems, in which minimum operational resource constraints are strictly enforced. As an exact approach, we present a Tailored Lagrangian Relaxation (TLR), in which the selection of constraints to dualize is guided by information provided by the MVFP algorithm. We present results and graphics to demonstrate the utility of our techniques for instances containing up to 25,000 blocks and 10 time periods.

Jan 1, 2013

By D. K. Marjaniemi

The U.S. Bureau of Mines inventoried and characterized mineral sites and production plants within 200 km of the border in both the U.S. and Mexico. Sources of information included the USBM Minerals Availability System, the USBM Automated Mineral Information System, the USGS Mineral Resources Data System, the Mine Safety and Health Administration Address/Employment File, and the literature. Three hundred seventy-eight major construction material and industrial mineral properties were identified and characterized in the U.S. and Mexican parts of the Borderlands. Sixty-six major metallic mineral properties were identified and characterized in the Mexican part of the Borderlands.

Jan 1, 1996

By Christopher J. Bise

INTRODUCTION The transportation of men, supplies, and mined material from an underground operation is the connecting link between the mine plant and the surface plant. Unless the mine is accessed by a drift or adit, some form of hoisting system is necessary for slopes or shafts. This chapter will deal with the selection of wire ropes and hoists, two of the most important consider¬ations when designing a hoisting system for an under¬ground mine. WIRE ROPES General A wire rope is designed to transmit forces longitudi¬nally along its axis. Wire rope is used in a variety of mining applications because of its flexibility, high ten¬sile strength, and dependability. Shaft hoisting ropes and principal slope haulage ropes are usually custom-¬built; however, proper rope selection for slushers, car spotters, etc. should not be overlooked. Wire ropes for shafts and slopes, since they represent the life line for the mines, should be of the very highest quality improved plow steel. This quality is necessary to deal with the conditions of loading, winding, vibration, abrasion, and corrosion. Tables I and 2 display the specifications for the typical wire ropes used for mine haulage applications. The 6 x 19-class haulage rope is used for most hoisting where abrasion is not critical. On the other hand, where abrasion is critical, such as a slope application, 6 X 7-class haulage ropes are preferred. For other mining applications, manufactur¬ers' handbooks should be consulted. Selection The selection of a wire rope for a mining situation consists of simply applying appropriate safety factors to a calculated maximum rope pull and comparing the result to the listed breaking strength of the rope under consideration. Table 3 can be used for determin¬ing the minimum factors of safety for wire ropes. To determine the maximum rope pull, the following quantities must be known: the rope weight in pounds (x), the conveyance weight in pounds (y), and the weight in pounds of the load in the conveyance (z). These values are used to calculate the load due to gravity, the load due to conveyance friction, and the load due to rope friction. When these loads are added together, as shown in Eq. 1, the maximum (static) rope pull (RPS) can be derived:

Jan 1, 1986

By R. A. Allwes

In-plane bending and torsion tests were conducted on full-scale masonry walls to evaluate three post-reinforcement designs. The designs were developed to minimize longwall mine subsidence damage to existing residential masonry foundations. The bending tests show that vertical and horizontal post tensioned tendons significantly increase the resistance of a masonry wall' to in-plane bending. The torsion tests reveal that post tensioned tendons increase a masonry wall's limit of deformation but do not increase its torsional stiffness. The torsion tests also show that the masonry units minimally contribute to the torsional stiffness of a masonry wall.

Jan 1, 1995

By Mohammad R. Jafari

The Camp Dresser & McKee (CDM) has been retained by the Sacramento Regional County Sanitation District (SRCSD) to design the Mather Interceptor, a portion of the South Interceptor and Mather Interceptor program. The Mather Interceptor consists of 14,667 feet of 54 to 72 inch gravity interceptor. Approximately 90 percent of the alignment will be constructed via tunneling. Cobbles and boulders in a sand/gravel matrix dominate the ground conditions combined with seasonal perched groundwater table at some of the deeper reaches of the alignment, impacting design consideration. This paper will present the results of a comprehensive geotechnical investigation conducted for this project and in-depth technical evaluation of various trenchless techniques feasible for tunneling in the cobble and boulder laden formations of this project. This paper will also present the risks and issues of the design alternatives and selection criteria.