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By R. J. Rice, K. F. Denning

Effect of iron on the removal of arsenic, mercury and selenium from gold mining effluents. Arsenic, mercury and selenium are common trace elements in gold tailing effluents that require removal before the water is either recycled or returned to a receiving body. One of the better methods of removal of these elements is the use of iron salts whereby, the metal is trapped on the freshly precipitated hydrolyzed iron oxides either by adsorption or enmeshment of the fine particulate and hence, removed from solution. The metal removal is effected by iron to metal ratio, pH, temperature etc. Pilot plant tests have shown that mercury can be reduced to < 5 ppb Hg, while full scale tests on arsenic and selenium have achieved levels of < 50 ppb As and < 10 ppb Se in well controlled systems.

Jan 1, 1993

By R. S. Shoemaker

It is said that there is nothing new under the sun and this is certainly true about refractory gold Ores. Ores which have been refractory to treatment have been the bane of the Metallurgist&apos;s life ever since gold has been recognized as a metal valued for its indestructability, malleability and beauty. Webster&apos;s Dictionary defines "Refractory" as; "Resisting control or authority, stubborn, resistant to treatment or cure, unresponsive to stimuli, difficult to corrode or draw out," And gives as a synonym the word "unruly." I don&apos;t think any metallurgist would disagree with these definitions as they quite accurately describe refractory gold ores as we know them and I wouldn&apos;t be a bit surprised if many of you in this room today had applied far stonger language to your own refractory ores in the course of your metallurgical test programs. Pliny the elder put it very well when he wrote in 79 A.D., Gold is the first of man&apos;s follies, Silver the second." Perhaps Pliny was speaking of "unassayable gold" or "incipient gold." These are truly refrac tory ores which probably existed before Pliny&apos;s time and although many people have claimed to have solved their metallurgy the untold wealth that lies within them has never been bankable. On the other hand, Virgil is his Aenead, could very well have been speaking of refractory ores when he wrote; "Quid non mortalia pectora cogis, auri sacra fames!" which translates as, Accursed thirst for gold! What doest thou not compel mortals to do. Certainly, gold was extremely rare at that time because it had to be recovered by much labor from the then refractory ores and their refractoriness caused the early metallurgists (or alchemists if you will) to seek an easier way to produce it; thus the long and fruitless search for the "philosopher &apos;s stone" which would aid in turn-

Jan 1, 1990

By Theodore J. Barrett

[One of the earliest records of pillar removal can be found in the 16th Chapter of Judges in the Old Testament. Here we read where the mighty Sampson removed the pillars from beneath the prison house causing the collapse of the structure resulting in his own death along with the deaths of the 3,000 Philistine occupants. Our problems at the Mi Vida Mine differ somewhat from those of Sampson of old, in that it is our aim first to remove the pillars and get out from under the back before the "house falls in" and, secondly, to remove the pillars without the lose of a single life or without even a single casualty. As of January 15, 1959, the Mi Vida accident record stood at 772 days without a lost-time accident]

Jan 1, 1959

By M. Rotz

In the minerals industry today, the ?low hanging fruit? that once existed to debottleneck production and improve recovery, while meeting market needs for quality in mineral processing operations, are more and more difficult to find. Systematic methods for establishing plant mass flow, recovery, operational efficiency and control strategy in context with customer specifications provides the necessary insight and confidence for plant operators to prioritize improvement projects in order to maximize return on investment (ROI) for the site. The evaluation of aggregate and industrial mineral processing plants requires the following steps when projecting cost saving opportunities: collecting background data, conducting a base-line evaluation, analyzing specific unit-operation performance, defining investment options, prioritizing the selected improvement opportunities and the implementing process changes. The following paper describes the approach and challenges of developing an improvement plan for a dry and wet mineral processing operation.

Feb 23, 2014

By Mark R. Rybak, James Delmonte, Travis Hartman

The City of Phoenix, Arizona designed a 7.2 km (4.5 mi) long water transmission main from the South Mountain Reservoir to the Ahwatukee Foothills Reservoir to address the growing demand for drinking water in the southeast valley. The pipeline design called for a bored tunnel in a very environmentally sensitive area. The Reach3B contract included an 2.44 m (8 ft) diameter TBM excavated tunnel, 1,847 m(6,060 ft) in length. The geotechnical investigation revealed that the tunnel would likely pass through zones of loose to moderately cemented soils (caliche). The primary tunnel support would consist of rock bolts, circular steel ribs, hard wood lagging, and mine straps. A TBM that could handle the ground conditions and allow for efficient ground support installation was required. This paper describes the construction of a small diameter rock tunnel in challenging ground conditions.

Jan 1, 2003

By M. K. Gangal, E. D. Dainty

The paper describes the capabilities of a micro-computer-based real time data acquisition system for monitoring and control of mine environments. Applications of such a system for monitoring the ventilation and air quality of a mine is outlined. The paper discusses the results of running a monitoring system with various environmental sensors in a simulated mine environment. The sensors used in this study are: carbon monoxide (CO), carbon dioxide (C02), nitric oxide (NO), nitrogen dioxide (NO2), sulphur dioxide (SO2 ), methane (CH4 ), air flow, absolute pressure, temperature and relative humidity. A performance evaluation of the monitoring system and sensors is presented.

Jan 1, 1987

By Naomi H. Harley, Daryl E. Bohning, Isabel M. Fisenne

INTRODUCTION Underground mines in many parts of the world have elevated levels of short-lived 222Rn daughters. Lung cancer implicating exposure to short-lived daughters is documented in the U.S., Czechoslovakia, Canada, Sweden, the U.K., France and Newfoundland. An elevated lung cancer mortality (in excess of that expected) has been observed when cumulative exposure to alpha emitting short-lived 222Rn daughters (218Po, 214pb 214Bi 214Po) is greater than about 60 working level months (WLM) [1]/ (Hewett, D. 1979). This is equal to an absorbed alpha dose of about 30 rads to shallow basal cells in bronchial epithelium. Long-lived alpha emitters are also present in underground mines, and especially uranium mines because of airborne particulates containing uranium. The 238U parent of this primordial series supports other long-lived emitters 234U 230Th, 226Ra, Pb(210Po) which are in some degree of radioactive equilibrium with the parent 238U. Airborne particulates can be present due to drilling on the face of the ore body as well as in all parts of the mine through resuspension from the mine floor. Particles from 1 µm to about 5 µm penetrate the nose with reasonable efficiency and deposit primarily in the tracheobronchial tree. They are removed by ciliary motion (the bronchial escalator) but deliver an alpha dose to basal cells in bronchial epithelium during clearance in the same manner as short-lived 222Rn daughters. It is the purpose of this work to indicate the alpha dose to basal cells in bronchial epithelium delivered by the long-lived emitters 234, 238U. The dose calculations reported here based upon a few measured values of these isotopes in air in uranium mines in New Mexico and Colorado. MEASURED 234, 238U IN URANIUM MINE ATMOSPHERES In 1979, the U.S. Bureau of Mines undertook a study to evaluate personal monitors to be worn by miners to measure short-lived 222Rn daughters. One of these devices sampled air at 100 cm3/min through a 13 mm glass fiber filter, with a small pump worn on the belt. Alpha particles emitted by 222Rn daughters on the filter were measured continuously by a thermoluminescent dosimeter (TLD) chip. Each monitor was worn by a miner for a 170 hour working month and approximately one cubic meter of air was sampled during this period. Six different mines were selected for the test in New Mexico and Colorado. The mines used either wet or dry drilling methods. Miners in each location were equipped with the personal monitors. Subsequent to their use in evaluating the shortlived daughters, Dr. Robert Droullard of the Bureau generously gave us these filter samples along with a few blank glass fiber filters from the same box of filters used in the study so that long-lived emitters present in these mine atmospheres could be determined radiochemically. Four of the samples have been run for 234, 238U. The radiochemical procedure for uranium is adapted from USDOE, Environmental Measurements Laboratory Manual (Harley, J.H., 1976). Briefly, the samples were placed in platinum crucibles, spiked with 232U tracer and pretreated with nitric and hydrofluoric acid. The residue was fused with potassium fluoride to transpose to pyrosulfate. The fused cake was dissolved in 7 [N] hydrochloric acid and the solution passed through an anion exchange column to isolate uranium. Iron was removed using mercury cathode electrolysis. Uranium was electrodeposited onto platinum dies and counted using solid-state alpha spectrometry. The samples from each type of mine (wet and dry) were analyzed. The samples in the "wet" mine in New Mexico were selected on the basis of the original TLD measurement because they were near the maximum occupational standard for radon daughters. These samples should also represent upper limits to longlived activity encountered, since they were obtained at drilling operations on the face of the ore body. Samples collected in the "dry" mine in Colorado were pot associated with a particular location in the mine and should be representative of a month long overall exposure in many locations and operations. The values are shown in Table 1. The two uranium isotopes are in equilibrium and their alpha activity

Jan 1, 1981

By Harry Sutcliffe

The paper discusses the nature of mixed face tunneling and suggests courses of action in planning, exploration, design and contract conditions to minimize problems inherent in this type of excavation.

Jan 1, 1981

By Walter E. Kramer

The advantages derived from the use of pellet burdens in blast furnaces are so great, that hematite ores are being converted into pellets in greater quantities each year. The conversion of these ores into pellets appears on the surface to be relatively simple. In reality, this is not so. Serious difficulties are encountered in drying these pellets that do not exist in the drying of taconite concentrate pellets. The ores that present problems are goethite and earthy hematites. Green pellets prepared from these ores have very law shock temperatures, 200-600° F. The shock temperature of a green pellet according to our definition is the highest initial temperature to which a green pellet may be exposed without suffering decrepitation. Decrepitation may involve spalling, fracturing or total disintegration. The poor shock properties of these green pellets result from the inability of the vaporized water to escape freely and easily as it is formed with¬out affecting the integrity of the pellet. As a consequence, the pellets must be carefully dried prior to induration. This careful treatment is costly. The slow drying process restricts productivity and requires larger furnaces than desired. The use of an additive to elevate the shock temperature of the green pellets would increase productivity. Bentonite is used in some pellet plants to improve balling but it raises the shock temperature only slightly. Nalco became interested in the shock temperature problem because of its activity in the development of organic pelletizing aids for taconite concentrates. The findings reported here are an outgrowth of our experimental work on the development of shock temperature additives.

Jan 1, 1967

By K J. Kidd

There is general understanding of hoisting systems throughout the mining industry. However, the relative importance of the various parameters influencing hoist selection and utilization is not completely understood. In order to determine if these parameters can be identified and prioritized, data covering 613 hoist installations were compiled. The 613 installations represent hoisting systems in 30 countries on six continents. This study compares data to historical trends, correlates design parameters in an attempt to identify underlying selection criteria, and comments on the apparent trends in recent developments in hoist design.

Jan 1, 1998

By Terry D. Vandell

The purposes of this presentation are: (1) to discuss the actual as well as potential incidents that have caused and that could cause groundwater contamination at uranium in situ leach mining sites and (2) to discuss remedial actions and solutions that have been or that could be implemented in the future to stop or prevent serious groundwater contamination from in situ leach mining in Wyoming?s Powder River Basin. Open pit, underground, and existing and proposed in situ leach uranium mine sites in the Powder River Basin are shown in Figure 1. In situ leach mining or solution mining for extracting minerals in liquid form is a relatively new addition to the list of conventional mining methods currently used to extract uranium in Wyoming&apos;s Powder River Basin. Basically, the in situ leach mining method involves: (1) the injection of a leach solution lixiviant (an acidic or basic oxidizing solution) into a uranium-bearing ore body, via injection wells, to complex the contained uranium, (2) mobilization of the uranium complex from the host material via creation of a soluble complex salt, and (3) surface recovery of the solution bearing the uranium complex via production wells. Uranium is then separated from the leach solution by conventional milling unit operations (ion exchange).

Jan 1, 1981

By Jim Morris

This paper will describe the excavation of a 5.4 percent decline at the Montanore Project for Noranda Minerals Corporation. The 5.3 m by 4.9 m tunnel was driven to provide access for the exploration of a major copper-silver deposit. Soft ground and conventional drill-blast mining were used on the 4,270 m tunnel. Ground support consisted of steel sets and concrete in the soft ground and pattern rockbolts providing the majority of the rock support. A special feature of the project was the use of conveyor haulage in conjunction with the drill-blast excavation.

Jan 1, 1993

By J. W. Cooksley

Pyrometasomatic zones are a type of replacement deposit, normally in a carbonate rock unit, which consists of a zoned, coarse-grained, generally iron-rich mixture of calcium and magnesium silicates. These zones or rock masses are also called ?skarn,? and ?tactite?. They are formed as a result of the interaction of a shallow intrusion of magma with a carbonate or calcareous host rock and are considered to be of hydrothermal origin. Three environments of pyrometasomatic deposits are depicted in Figure 1. Of course, the interaction takes place at high temperatures. Pyrometasomatic zones are categorized as calcic or magnesian, depending on whether the intrusive interacts with a limestone or a dolomite. Common pyrometasomatic zone minerals are garnet, epidote, quartz, calcite, wollastonite, actinolite, hedenbergite and diopside. Pyrometasomatic zones are of considerable economic importance because they contain ore deposits of tungsten, molybdenum, copper, lead, zinc and iron. According to Rose and Burt (1979), the chronological sequence in the formation of a ?typical? pyrometasomatic deposit is as follows: 1. Shallow intrusion of magma at 900-700°C into carbonate sediments.

Jan 1, 1981

By D. W. Agers

This paper is an extension of previous work evaluating a new extractant, LIX®-64, for recovery of copper from dilute acidic solutions. Large scale pilot plant operations have confirmed the technical and economic feasibility of the process and, with minor exceptions, scale up parameters obtained by previous laboratory work. Operating problems encountered in the pilot plants are discussed. Design parameters for-scale-up to commercial plants are presented and discussed along with a revised capital cost estimate. The future pilot program is discussed, including minor design changes and the effect of entrained organic on dump leaching efficiency.

Jan 1, 1967

By H. P. Ehrlinger

The Negociacion Minera Santa Maria De La Paz mining operations are located at La Paz (some eight miles West of Matehuala), State of San Luis Potosi, Mexico. These operations consist of a single copper-silver property, called the Dolores mine and a number of silver-low base metal properties. The ores from these several mines are transported by rail, or truck, to the central milling unit. The milling unit has two separate sections to treat the two types of ore. The ores from the several silver-base metal mines are mixed at the mill as they arrive. Up to the present time the silver-base metal ores have been milled to produce a bulk concentrate which carries valued in gold, silver, copper, lead, zinc, cadmium and considerable arsenic. In such concentration the zinc and cadmium values are lost to the operations in their liquidations as they are shipped as lead concentrates. Since these ores have exceptional quantities of arsenic which is concentrated in the milling process, these bulk concentrates have to be sent to a smelter for pre-smelting operations to remove the arsenic.

Jan 1, 1964

By F. N. Earll

4.1 – DEFINITIONS 4.1.1-MINERALS, ROCKS, ORES AND NONMETALLIC MINERALS F. N. EARLL A mineral is a naturally occurring inorganic element or compound. Most minerals are distinctly crystalline in habit, and many commonly occur in well-formed crystals or crystalline aggregates, but a few species are characteristically amorphous or noncrystalline. Nearly 2,000 mineral species are now recognized but, perhaps fortun¬ately, a rather large proportion are rarely encountered. Even so, the application of modern mineral-detection and identification techniques reveals the presence of surprising numbers of mineral species, even in deposits of outwardly simple mineralogy. A rock is an aggregate of grains or crystals of one or more minerals. Some rocks are essentially monomineralic. Thus, limestone consists largely of the mineral calcite, and many sandstones are dominantly quartz. Most rock varieties, however, contain a number of mineral species, and their classification or identification depends upon the minerals present, their relative abundance, and such factors as rock tex¬ture and origin. Ore is defined as an accumulation or deposit of one or more minerals that can be exploited at a profit. The profit criterion commonly is taken somewhat liberally, however, for, although always present, the specific mineral content that constitutes a viable product is transitory. The term ore, usually, but no longer consistently, is restricted to the description of mineral deposits that are of value for their metal content. Nonmetallic deposits, although similar to metallic ores in many respects, generally are valued for the minerals or compounds present, as with rock salt (halite), rather than for individual contained elements, though such minerals as elemental sulfur are of much value. 4.1.2-ROCK TYPES F. N. EARLL Rocks arc grouped tinder three broad headings: (1) igneous rocks formed by the crystallization of magma; (2) sedimentary rocks formed by surface processes of weathering and deposition; and (3) metamorphic rocks, which may have been derived from either of the foregoing, but have undergone important physical and/or chemical changes through the application of heat or pressure, or both. The three groups can he further subdivided for convenient reference. Thus, igneous rocks are described as being abyssal or plutonic if formed at great depth, hypabyssal if formed at intermediate depth, and extrusive or effusive if formed at or on the earth&apos;s surface. The sedimentary rock group is similarly subdivided into clastic sediments and chemical precipitates. The clastic sediments form by deposition of preexisting minerals that were released from their place of origin by weathering and were transported to their point of deposition as discrete grains

Jan 1, 1973

By T. M. Needham

Increasing ore hardness led to a gradual reduction of mill throughput rates. This, combined with declining head grades and low gold price, prompted a review of milling practice at Kidston. Plant trials and computer simulation of the grinding circuit indicated the potential to increase mill throughput by up to 451 by reducing SAG mill feed size. Secondary crushing and additional ball milling capacity were installed. Commissioning was carried out successfully in September/October 1992. Design, operation and problems of the expanded circuit are discussed, and recent operating results are presented.

Jan 1, 1994

By David J. Akers

In past years, water drainage control in coal mines has been primarily directed on the basis of water quantity rather than quality. Due to the recent intense interest in total ecology and environment, emphasis has shifted to the point where the water exiting from a mining operation may be of better quality than when it enters. In most operations this has meant the use of treatment methods (neutralization) while the technology for the prevention of acid drainage is being developed or refined. To date, underground abatement of acid formation has generally been less expensive but also less effective than surface treatment of the mine water. It seems probable that total mine water pollution control will have to include both underground abatement and surface treatment methods. The general acid producing reaction involving the oxidation of pyrite - 2FeS2 (pyrite) + 702 + 2H20 ? 2Fe2S04 + 2H2SO4 - is well known, even though the individual steps are not clearly understood. The major implication of this reaction, that acid production can be eliminated by not allowing the contact of pyrite with free oxygen or water, has been well substantiated both in the laboratory (1,2) and in practice. (3) Underground abatement or control processes can be generally classified into two types: (1) the effective control or elimination of acid causing reactions within the mine, and/or (2) the reduction or prevention of water flow into and out of the mine. Recognizing the fact that these two types may be directly inter-related, this paper will, for the purposes of clarity and simplification, discuss each separately.

Jan 1, 1973

In early March 2011, a 6.2 m (20.3 ft) diameter Rob-bins Double Shield tunnel boring machine (TBM) crossed the finish line in Sochi, Russia. The machine completed a 4.5-km- (2.8-mile-) long section of tunnel that will ultimately become part of the transportation infrastructure for the 2014 Winter Olympic Games. The TBM advanced through difficult ground at aver-age rates of 100 to 120 m/week (330 to 390 ftpw) for contractor OJSC Bamtonnelstroy, a division of the SK Most Company. The section of tunnel will ultimately become a service tunnel for Complex #3 - a section of Sochi?s transportation infrastructure under construction, which includes road and rail tunnels. A second, 10 m (32.8 ft) diameter Robbins Double Shield TBM is currently excavating the parallel 4.6-km- (2.9-mile-) long main railway tunnel using a continuous conveyor system for efficient muck removal. A 13.2 m (43.3 ft) diameter highway tunnel is also under construction. The 6.2 m (20.3 ft) Robbins TBM achieved high rates despite difficult conditions. The tunnels run through mixed ground including massive to completely fractured limestone with clay seams. Some sedimentary rock including sandstone and siltstone is present, along with fault zones consisting of breccias and conglomerates. In May 2010, the machine was stopped after encountering a significant fault zone consisting of broken rock and running soft ground. Field service personnel and crew successfully freed the machine by excavating a bypass tunnel around the TBM, freeing the cutterhead. Following the restart, a combination of continuous probe drilling and ground treatment with cement silicate and foam kept the machine moving forward.

Jan 1, 2011

By M. K. Han, K. N. Han, P. B. Queneau, W. J. Dawson

The development and scale up of hydrothermal synthesis processes for manufacture of high performance materials is discussed. Traditional hydrometallurgical processes are reviewed, leading into a discussion of process development concerns for manufacture of modern materials. Three case studies are presented, including a piezoelectric ceramic, barium titanate for multiyear capacitors, and high purity chromium metal. Factors for selection of reactor design are presented, as well as results of scale-up studies on the three products.

Jan 1, 1993