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By E. H. Christiansen

The most valuable gem- quality red beryl comes from the Wah Wah Mountains of south-western Utah (Fig. 1). Red beryl occurs as a secondary mineral in topaz rhyolite. Marketable crystals from the Wah Wah Mountains have been produced from the Violet Mine, operated on a limited scale since 1976 under the ownership of the Harris family of Delta, UT. From 1989 to 1995, production from the mine amounted to more than $3 million with an inventory of several million dollars of unsold gems (Harris, 1995). In 1994, Kennecott Exploration leased the mine and surrounding claims to determine reserves and feasibility of gem recovery. Mining and exploration activity are continuing. Previous work on red beryl has dealt mainly with crystallographic, chemical and optical properties of the crystals (Shigley and Foord, 1984) with only general descriptions of the geology (Ream, 1979). However, the conditions needed for formation of red beryl have not been well constrained. It is generally proposed that beryl originates by precipitation in fractures and vugs from high-temperature gases as they are released from slowly cooled rhyolite lava. Dozens of topaz rhyolite flows and domes, similar in composition to the beryl-bearing flow in the Wah Wah Mountains, occur across the western United States (Christiansen et al., 1986). All of these flows devitrified to form vapor-phase topaz and locally other vapor-phase minerals such as bixbyite, garnet, hematite, pseudo-broo- kite and fluorite. But the occurrence of beryl is rare. Even within the rhyolite flow that hosts the red beryl, the productive open pits comprise only a small fraction of the surface area of the flow. Apparently, the conditions that favor the formation of red beryl are rarely achieved. Geologic setting The rhyolite flow that hosts the red beryl deposit lies along the eastern flank of the Wah Wah Mountains (Fig. 1). Prevolcanic rocks consist of Proterozoic, Paleozoic and Mesozoic sedimentary rocks that were folded and thrust to the east during the Sevier orogeny. Cenozoic volcanism began about 34 Ma. It consisted mostly of large volume dacitic ash flows and lesser volumes of low- silica rhyolite and andesitic lava flows. Beginning about 23 Ma, the style and composition of volcanism changed to smaller-volume, ash-flow and dome-forming eruptions of high-silica rhyolite and trachyandesitic lava. These rocks form the Blawn Formation of which the beryl-bearing rhyolite is one member (Best et al., 1987). Abbott et al. (1983) reported a K-Ar age of 22.1 + 0.8 Ma for this flow. It is probably the oldest topaz rhyolite flow in the Wah Wah Mountains. A subsequent episode (12 to 13 Ma) of bimodal magmatism produced the Steamboat Mountain Formation. The rhyolitic part of that is locally topaz-bearing. Displacement on the late Cenozoic extensional faults that formed the north-trending mountain ranges began about 22 Ma. Geology of the Violet Mine The rhyolite that hosts the red beryl deposit is part of a flowldome complex that overlies nonwelded tuff of cogenetic origin. This rhyolite is exposed over an area of about 9 km2 (3.5 sq miles) (Fig. 1). An unknown additional portion of the rhyolite is concealed beneath younger mafic lavas and sediments.

Jan 1, 1997

By S. D. Thompson

Since 1965 several researchers have independently developed computer models for designing gathering belt and surge bin capacities in underground coal mine belt systems. Table 1 summarizes the models applicable to U.S. mining systems. Most of the models, employ the Monte Carlo simulation technique. Basically, the belt loading at each loading point is randomly produced from probability distributions. In some cases, a combination of deterministic calculations and probability distributions are used to simulate the loading. Once the loading is simulated, it is systematically moved through the belt system in a deterministic fashion based on belt speeds, belt lengths, and storage bin discharge rates. The coal flowing from each loading point is tracked as it moves through the belt system. When the loading from tm different sources combines on a belt or in a surge bin, checks are made to determine if capacities have been exceeded. If capacities have been exceeded the amount of spillage is calculated. At the end of the simulated time period, the cumulative spill- age is used to evaluate the belt and surge bin capacities. Naturally, a considerable amount of spillage indicates the capacities are unacceptable. Acceptable capacities are generally indicated by minimal spillage. Numerous trial simulations are often necessary to find the acceptable capacities.

Jan 1, 1987

By Roshan B. Bhappu

Although the economic importance of recovering copper by leaching of mine work dumps from open-pit operations has been realized for some time, serious attempts to understand and to improve such operations through scientific research has been made only in recent years. This progress report covers the results of chemical, physical, and biological studies pertaining to the dump leaching process and discusses salient features and parameters that may be helpful in improving such operations.

Jan 1, 1968

By Mustafa Fener, Masoud Rostami, Sair Kahraman, Behnaz Dibavar

The paper introduces a new rock mass cuttability classification (RMCC) system for roadheaders used in coal mines. It includes performance prediction models for both axial and transverse roadheaders, based on six parameters: uniaxial compressive strength, Cerchar abrasivity index, volumetric joint count, strike and dip of joints, joint aperture, and groundwater condition. The study validates the RMCC system through field and laboratory measurements, showing high correlation coefficients between net cutting rates and RMCC indices.

Nov 1, 2023

By S. Shankar

Available literature on the effect of re-entrainment on overall airborne dust concentration in mine airways or the fundamental mechanisms of coal dust re-entrainment in mine atmosphere is scant. Therefore, as part of the Respirable Dust Center's ongoing research, a three part study was envisaged: study of the re-entrainment phenomena of anthracite and bituminous coal dust particles in a wind tunnel under the influence of varying air velocities; study of the same in the Lake Lynn Laboratory Mine of the USBM with both airflow and walking by personnel causing re-entrainment; and mathematical modeling and computer simulation of the re-entrainment phenomenon. In this paper, results from the re-entrainment studies in the wind tunnel and the Lake Lynn Laboratory Mine are presented. Further, the results from the wind tunnel studies are compared with the results from in-mine studies conducted at the Lake Lynn Laboratory Mine of the USBM. Comparing the results from the two studies it was observed that increasing air velocity increased the rate of re-entrainment, but increased time of exposure decreased the airborne dust concentration. Compared to same size particles, a mixture of sizes created more airborne dust concentration when re-entrained. It was also observed that contribution of airborne dust concentration due to airflow was negligible compared to the contribution due to walking.

Jan 1, 1995

By M. J. Virnig

A flowsheet for the recovery of nickel and cobalt from laterite ores has been developed which involves acid leaching followed by hydroxide precipitation of the metal values and then releaching of the hydroxide cake with ammonia. Investigations of the chemistry of extraction of nickel by LIX® 84-1 and a developmental reagent, XI-84-IT, along with the physical properties of the organic phases are described. Based on these investigations, suggestions with regard to design of a solvent extraction plant and operating conditions are made.

Jan 1, 1999

By R. R. Klimpel

The use of chemical reagents in flotation has been studied in great detail, e.g. (1, 2, 3, 4). Important progress has been made on the understanding of surface chemistry concepts involved in flotation. However, such scientific studies are often very complex even for rather simple idealized systems. Therefore, the deve- lopment of predictive or quantitative tools for plant engineering evaluation is still in the evolutionary stages. Until further progress in fundamental work is achieved, the operating engineer is faced with semi-empirical physical testing of reagent changes on several sizes of the actual equipment under study to be confident of the economic viability of any change.

Jan 1, 1980

By F. Rudloff, C. Karageorgos, J. Moyo, I. Boadi, M. Struble, B. Lumsden

Over it’s more than 100-year history, the Kennecott operation has often been at the forefront of innovation; driven by the demands of the lower grade ore-body and the higher costs of operating in the US where wages are generally higher and regulation more restrictive. One way of reducing operating costs in c/lb is to increase the lbs produced at minimal cost. Despite the relatively coarse grind at Kennecott - about 30% >150μm, approximately 20% of the Cu lost to tail is liberated chalcopyrite in the <20μm fraction, and about 30%-40% in the <37μm fraction. In 2020 Kennecott undertook a detailed plant scale test of the magnetic aggregation technology to increase copper recovery by reducing fine copper losses. A paired statistical plant test of magnetic conditioning on one rougher line showed a 1.12% increase in Cu recovery to 97% statistical confidence. The next challenge, unforeseen at the start of the project, was the fabrication and transportation to site of the equipment for the three remaining rougher rows, during the severe supply-chain constraints of the Covid pandemic in 2021. This resulted in delays and unforeseen costs as world-wide transportation became chaotic, particularly transportation via west coast USA. Nevertheless, the project was completed and commissioned, with only minor delays and cost increases, due to a flexible approach to overcoming the hurdles encountered.

Feb 1, 2023

A PDP 11/34 computer has been inter- faced to existing instrumentation in a 400 tph rod-mill/ball-mill grinding circuit and programed with a Kalman filter to estimate several unmeasured variables. A dynamic two-size- fraction model of the circuit is used to predict the complete state of the circuit including particle size distributions around the circuit, mass holdups and flowrates, the ball-mill grinding rate, water additions and cyclone parameters. Online measurements of sump level, slurry densities and product particle size are used to update the model values sequentially on a 20-second interval. This procedure results in optimal estimates of circuit variables given the relative reliability of measurements and the accuracy of the model.

Jan 1, 1983

By S. M. Khandrika

Most of the coal presently used by the utility industry is cleaned at preparation plants employing wet processes. While water is the mainstay of coal washing, it is one of the least desirable components in the final product causing a reduction of the heating value as well as handling difficulties. Currently available dewatering techniques are inefficient for dewatering very fine coal (minus 325 mesh). The US coal industry has expressed serious concern about utilizing advanced cleaning processes such as column flotation because an efficient and economical dewatering process is not available.

Jan 1, 1992

By Furuyama Takashi, Mori Sukeyuki, Hara Tsuyoshi, Fukushima Yujin

In mineral processing practice, flocculation is largely established as an engineering technique of waste water treatment and the study of parameters increasing the settling velocity of particles is still of great importance to improve the process. Further investigations were made using quartz (Q89) and fluorite samples (F91) which included 58.8% and 65.8% of -2.3 µm particles respectively. In all the experiments the flocculation phenomena were observed varying the pH value of the aqueous suspension. In contrast to quartz particles (Q89) which did not flocculate for all pH values, it was, noticed that fluorite particles (F91) flocculated in the alkaline range of pH over 11. With an aqueous suspension containing equal quantities of Q89 and F91, a hetero-flocculation of particles was observed at a range of pH below 10. In this case, the maximum floc size of the hetero-flocculation was 37.0-26.2 µm This size was about three times larger than when quartz (Q84) and fluorite particles (F85) were used with 32.4% and 40.4% of -2.31 µm particles respectively. Besides, in the experiments using Q89 and F91, the maximum size of hetero-flocculated single particles was found to be 6.54 µm instead of 3.27 µm as obtained with Q84 and F85.

Jan 1, 1995

By W. L. Freyberger

In many papers concerned with fundamentals of the froth flotation process, authors have considered the contents of a flotation cell to be comprised of two immiscible phases, the froth and the pulp. I (Of course, each of these phases is in turn made up of several solid phases plus air and water.) This generalized concept of the flotation system can be extended by considering the cell contents to include two phases: an extracting phase, the air bubbles plus the collector, which removes a selected mineral component from the second phase, the ore pulp. Thus, there is an analogy between a flotation system on the one hand, and chemical extracting systems, such a solvent extraction system or a leaching system, on the other hand. Such extracting systems may be operated in cocurrent or countercurrent fashion. This paper includes first a brief discussion on the general nature of cocurrent and countercurrent operation as applied to froth flotation, and then presents the experimental results of flotation of a specular hematite ore by each method, using a tall oil fatty acid as collector. Cocurrent Flotation A conventional flotation circuit involving roughing, scavenging, and cleaning flotation is illustrated schematically in Figure 1. In such a circuit the col¬lector, or extractant, and new feed ore enter together at the head of the rougher circuit, and flow cocurrently to the scavenger circuit where more collector is added. According to this practice, sufficient collector is added to the head of the rougher (and scavenger) so that the final tailings are of low enough grade to be discarded. Since the flow of collector and ore is cocurrent, the process consists of single stage contact between the extracting phase and the ore pulp. If the scavenger concentrate is recycled to the head of rougher, the overall circuit has some of the characteristics of countercurrent flow. In such a case part of the extractant (collector) is added at the discharge end of the circuit, and may

Jan 1, 1971

By W. M. Cross

Optical fibers have revolutionized the telecommunication industry, because of their ability to transmit large amounts of data over long distances. Without optical fibers many of the communication technologies on which business, industry and research rely would be impossible. In addition to their use as communication devices, optical fibers are often used as sensors. Despite the great promise that optical fibers have for the development of many types of remote sensing devices, few remote sensing devices have been built for use in the mineral industries. This paper will describe the use of optical fibers as sensors for surfactant adsorption at mineral surfaces.

Jan 1, 1995

By R. Bruce Tippin

because of the mineral&apos;s high monetary value and the spotty occurrence of free gold in the deposit. Setting up a plant sampling procedure by simply applying the usual statistical sampling theory was questionable. Two sampling concepts were considered in the sampling study: o a sufficient number of assays can be taken such that the average determined from these individual samples represents a known quantity of ore. o a sufficient weight of sample can be taken such that when assayed it represents a known quantity of ore. The test program included evaluation of sampling techniques, sample preparation and analytical methods. The overall sampling program is depicted in Figure 2.

Jan 1, 1985

By H. S. Duzgun, N. Demirel

Estimating productivity of a walking dragline is of paramount concern to mining engineers and mine planners. Risk based evaluation of the dragline productivity is a valuable tool to estimate the dragline’s long-term availability, to develop preventive maintenance plans and to make future projections about the dragline’s performance. This paper aims to provide mining professionals with an overview of risk assessment methodology for productivity of two walking draglines, Page 736 and Marion 7820, which have been operating in the Tunçbilek openpit coal mine of Turkish Coal Enterprises (TKI) in Turkey. The study encompasses three main stages: (i) acquiring of monthly maintenance records, operating hours, mechanical and electrical failure hours between 1998 and 2009; (ii) reliability modeling using mean time between failure data and (iii) determining hazard rate and consequences to compute risk associated with dragline productivity. The results showed that that Page 736 (15.29 m3) seemed to be more reliable and less likely to fail when compared with Marion 7820 (30.58 m3). The operating hours without failure range from 41 to 51 hours with 50% reliability.

Jan 1, 2011

By Pascal Deschamps

"INTRODUCTION During the last decades, many underground facilities for the storage of hydrocarbons have been excavated worldwide and the technology is fully mature. Similarly to other underground structures, the initial basic design has to be adapted along with the work progress, in order to cope with the actual site conditions and in particular the geology, hydrogeology and associated rockmass quality. In addition, Client’s or underground Contractor’s constraints (such as resources availability, schedule or cost impact) may vary from design to construction and require last minute adjustments. Engineers are required to introduce flexibility and anticipation of unexpected situations (similar to the above-mentioned) while conceiving large underground facilities. Although most of the cases require only minor adaptations, crucial parts of the facility have sometimes to be considerably modified and reviewed. This article will present four cases evidencing how the design of one of these essential structures - the concrete plug – has been adjusted during site implementation without impairing the initial performances. Hydrodynamic containment The product containment of the unlined caverns discussed here is ensured by the principle of hydrodynamic containment. A permanent water flow is naturally or artificially maintained with an orientation toward the storage cavern and then, neither product-tight membrane nor lining are required. The hydraulic gradient (and the associated water flow lines), being directed from the surrounding mass toward the cavern, prevent from outward migration of the product. If the hydraulic gradient is not sufficient or if the water table is evidencing instability, water can be artificially injected into the rockmass through purpose-built boreholes, drilled from dedicated galleries. This water injection system, called the water curtain, is generally located several tens of meters above the level of the cavern. This principle is illustrated here after."

Jan 1, 2016

By M. A. Reyes, J. Bickson, J. R. Srednicki

Federal laws mandate the presence of refuge alternatives (RAs) in underground coal mines and provide guidelines for harmful gas removal. After an explosion, harmful gases can follow survivors into an RA and can reach a deadly concentration. Investigators from the National Institute for Occupational Safety and Health (NIOSH) tested 12 ventilation system configurations (VSCs) to purge sulfur hexafluoride (SF6) tracer gas from a built-in-place (BIP) RA in the Experimental Mine in Bruceton, PA. Using a borehole air supply, tests were conducted with airflows of 750 and 1,000 standard cubic feet per minute (SCFM). Excluding a VSC where the air inlet was 1.98 m (78 in) from the air outlet, the results show that the time to purge the SF6 concentration from 1,000 parts per million (ppm) to 25 ppm ranged from 26 to 29 minutes for an airflow of 750 SCFM and ranged from 18 to 23 minutes for an airflow 1,000 SCFM. Mines can use this information to reduce purge time in case of a mine disaster and determine which VSC to avoid. INTRODUCTION After a fire or an explosion in an underground mine, the concentration of carbon monoxide can reach a fatal level. In a mine disaster, the main goal is to escape. However, if miners cannot escape, they have to migrate to a location to find refuge and, if possible, communication, and a borehole source for a fresh air supply. To ensure survival of the miners, Federal laws mandate the presence of a refuge alternative (RA) within 304.5 m (1,000 ft) of the nearest mining face. In addition, Code of Federal Regulations Title 30 CFR Section 7 sets the guidelines for personnel tracking, RAs, and the removal of noxious gases in underground coal mines (Mineral Resources, 30 CFR, 2014). Federal regulations define an RA as a protected, secure space with an isolated atmosphere and integrated components (Mineral Resources, 30 CFR, 2014). There are three types of RAs: portable metal RAs, portable tent-type RAs, and built-in-place (BIP) RAs. A BIP RA is constructed using masonry or other stoppings to create an isolated space in a mined-out area. Blast doors are installed in one or both of the stoppings for the miners to enter the RA. Furthermore, RAs must provide the following components: breathable air, food, water, air monitoring, and harmful gas removal. Federal regulations have emphasized the mandate for breathable air and harmful gas removal in the following words: “Purging or other effective procedures shall be provided for the airlock to dilute the carbon monoxide concentration to 25 ppm” (Mineral Resources, 30 CFR, 2014). The purpose of the mine ventilation system is to provide a sufficient quantity of air to the underground mine workings, to dilute methane and other contaminants, to maintain a suitable working environment, and to prevent accidents from happening (Cheng and Wei, 2014). In addition, the organic nature of coal amplifies risks from poisonous gases, explosions, and fires (Engström et al., 2018). If an underground coal mine ventilation system fails after an explosion, the concentration of toxic gases, most notably carbon monoxide, will increase. Carbon monoxide is dangerous because it creates tissue hypoxia by binding to hemoglobin (Özmen and Aksoy, 2015).

Jan 1, 2019

By J. Sanko

When faced with the task of designing a process control system the control engineer must consider the following: 1. The type of process to be controlled and the manner in which the process must be controlled (the algorithm). 2. The type of equipment to be used to implement the control system. 3. A means of describing the control system for use in the following areas: a. Project engineering. b. Procurement of the control system equipment. c. Plant startup. d. Operator training and reference.

Jan 1, 1981

By E. J. Mayhew

Bentonite and newly discovered deposits of sepiolite, saponite, and hectorite are now being processed and marketed from the Amargosa Valley of Nevada. All of these deposits are large. The bentonite has been known for decades and is the whitest known. The only other sepiolite deposit is in Spain. The only other commercial hectorite deposit is at Hector, California. No other saponite deposit is known. All the components except bentonite are hydrous magnesium silicates. The bentonite is mixed layer Na-Ca. All the materials have characteristics unique to their locale and type, such as high yield point for drilling muds and liquid suspending agents. The sepiolite has geothermal stability. Figure 1.

Jan 1, 1979

By A. D. Hammond

Vanadium is a transition metal, ductile, silver-gray metal. It is harder than most metals and steels and it has a good resistance to corrosion, it is stable against alkalis, sulfuric and hydrochloric acids. Vanadium is oxidized in air about 660 °C, although an oxide layer forms even at room temperature. The chemistry of vanadium is noteworthy for the accessibility of the four adjacent oxidation states 2-5. In aqueous solution the colors are lilac V2+, green V3+, blue VO2+ and, at high pH, yellow VO42-. Considered to be as abundant as zinc, metallic vanadium is not found in nature, but it is known to exist in about 65 different minerals. Economically significant examples include patronite (VS4), vanadinite (Pb5(VO4)3Cl), associated to the uranium mineral carnotite (K2(UO2)2(VO4)2?3H2O) and in a vanadium mica called, roscoelite K(V3+,Al,Mg)[(Si,Al)4O10](OH)2. Other important vanadium ore oxides are montroseite (V,Fe)O(OH) and corvusite (Na,Ca,K)V8O2.4H2O. Much of the world&apos;s vanadium mine production comes from magnetite-hosted deposit and to a lesser extent, in sedimentary-hosted sandstone. Vanadium is also present in bauxite and in fossil fuel deposits such as crude oil, coal, oil shale and tar sands. In crude oil, concentrations up to 1,200 ppm have been reported. A significant vanadium production comes from the processing of petroleum residues, fly ash and recycling spent catalysts. In 2011, metallurgical applications accounted for 93% of the use of vanadium. Here, an alloy called ferrovanadium is utilized to strengthen steel to be used as rebar in the construction industry, in the manufacturing of axles, crankshafts, gears and chassis in the automotive and transportation industries and in the manufacturing of high-speed tools. In the aerospace industry, vanadium is utilized as a titanium alloy in the manufacturing of airframes and jet engines. The reason for the wide use of vanadium as alloy is its high strength-to-weight ratio, the highest of any engineered material on earth. The major non-metallurgical use of vanadium is in the production of catalysts for the chemical industry. The most commercially important compound is vanadium pentoxide (V2O5), which is used as catalyst in the production of sulfuric acid.

Feb 23, 2014