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By G. S. S. Raman, M. S. Klima

The effects of pressure and cake thickness were studied using a split-plot design for pressure filtration of a fine refuse slurry obtained from a bituminous coal preparation facility. Pressure filtration offers the potential to significantly reduce the moisture content of the fine refuse stream with the addition of little to no flocculants, thereby minimizing the volume of refuse stored in impoundments and providing a recycle water stream for use within the plant. Experimental results showed that the final cake moisture decreased with increase in pressure and decrease in cake thickness. In addition, specific cake resistances calculated for the various tests indicated an increasing trend with increasing pressure and decreasing cake thickness. With increase in cake thickness, an increase in cake moisture and the weight of solids deposited in the cake was observed. An ANOVA analysis indicated that both cake thickness and pressure significantly affected the cake moisture, while only cake thickness statistically influenced the weight of solids in the cake. A regression model was developed with an R2 value of about 0.99 to relate cake thickness, the single largest statistically significant factor, with the weight of solids in the cake. Filter capacities were calculated in terms of the solids deposited per unit time based on a product specification of 25 percent cake moisture, and it was observed that the thinnest cake had the highest filter capacity.

By Leon Y. Sadler

Equations which predict the unsteady-state response of the continuous froth flotation cell to changes in operating conditions are necessary for the rational design of an automatic flotation cell control system. Unfortunately application of automatic control to froth flotation separation equipment has lagged behind application to other types of separation equipment (for example distillation columns, absorbers, liquid-liquid extractors, etc). This may be due partly to the unavailability of suitable mathematical models for predicting the dynamics of continuous mechanical froth flotation cell. This paper presents the results of a comparison of four dynamic flotation models (in transfer function form) using the same set of unsteady-state continuous flotation data. One of the transfer functions tested has been presented previously in the literature (1), another (2) has been accepted for publication, and two are given here for the first time. In addition, data are presented which confirm earlier findings that the mixing in the rotor-stator type cell is nearly perfect. The specific purposes of this paper are to: (1) provide the automatic control systems designer with several alternative dynamic mathematical models of the continuous mechanical froth flotation cell (2) give some idea of the relative a¬bility of each model to predict unsteady-state behavior by fitting each model to the same set of experimental stimulus-response flotation data and (3) provide more insight into the macro-mechanisms prevailing in the continuous mechanical flotation cell. The dynamic models which are presented and tested here all relate the time variation of the concentration of a given floatable mineral in the tailings to a time-dependent disturbance in the same floatable mineral concentration in the feed to the flotation cell.

Jan 1, 1972

By T. T. Toomver

The evolution of Inco's Selective Reduction Smelting Process as practised today is described, beginning with the initial laboratory experiments on small samples to the processing of large bulk samples through pilot plant equipment. For both the Guatemalan and Indonesian (Soroako) ores, the initial screening tests using hydro-, vapo-, and pyro-metallurgical processes showed that the latter was the most promising both metallurgically and economically. Later, larger scale tests confirmed the earlier testwork.

Jan 1, 1979

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 R. Mensah-Biney

The aqueous biphase separation process (ABS) has been used to separate ultrafine industrial minerals. The partition behavior of TiO2, Al2O3, Fe2O3 and kaolin was not pH dependent. The partition behavior of SiO2 was, however, pH dependent. The partition coefficient of kaolin in PEG 3400/ Na2CO3 biphase system was = 150 and that of the silica in the same system was = 0.02, resulting in a separation factor of = 8500 between kaolin and silica. The aqueous biphase separation system was used to separate free silica from kaolin in a raw clay sample from Mexico. The partition behavior of mica, feldspar and clay from North Carolina was also evaluated.

Jan 1, 1999

By W. Bassow

In June 1972, when the United Nations convened its historic Conference on the Human Environment, only 24 countries had established government agencies with environmental responsibilities. Of these, 11 were in the industrialized world, 13 in the Third World. By 1985, the number had dramatically surged to a world-wide total of 145, with the greatest growth among the developing countries to 110, an increase of almost 1000%.

Jan 1, 1988

By C. Allen, H. Zhang, L. Falk

Shock loss occurs when there is a change in the area of a drift or airflow direction. These shock losses accumulate throughout the ventilation system and will increase the mine resistance as underground development deepens or becomes more complex. Hence, shock losses should be carefully considered when establishing the resistance through a series of branches as they can be a significant contributor to the estimated mine resistance. Using computer software to simulate a ventilation system is common but applying reasonable shock loss factors in the software is not a simple or direct process. Determining shock loss values includes the consideration of historical measurements, application of factors and formulas from literature based on the geometry and complexity of junctions, and the geometry variation at different locations. For example, the shock loss at the bottom of a ventilation raise can consist of a 90° bend and a sudden area change. This paper presents an approach for estimating shock loss factors near raise junctions using computational fluid dynamics (CFD). Current and future work will also be compared with field measurements. Results from this approach are compared with software defaults as well as classical techniques in published literature and standards.

Sep 1, 2024

By Jr. Moulton

Extractions of minerals from Searles Lake brines have taken place since 1873. Early operations were for borax and raw trona found on the surface, expanded after 1914 to include potash, salt cake, and soda ash. A new soda ash plant now in operation will double area production. The evaporite beds were formed by desiccation of Eastern Sierra runoff. The resulting series of brine-bearing salt beds supply the fluids necessary to feed the area chemical plants. Production methods include evaporation and crystallization for potash, borax, and salt cake; carbonation of brine to recover soda ash; and organic extraction of borax.

Jan 1, 1980

The roasting process of copper concentrates containing variable quantities of arsenic in a fluidized bed regime was analyzed, considering the technical literature published on the topic in the last quarter century. Although emphasis has been given to the analysis in the fluidized bed regime, other processes have also been considered, under a reducing, neutral or oxidizing atmosphere. The kinetic mechanisms of roasting, as well as the models that have been applied or those likely to be used to explain the kinetics of arsenic removal, are analyzed. Regarding the kinetic mechanisms, those that have been applied to copper concentrates with both high and low arsenic content are included. The roasting kinetic model includes the kinetic data analysis techniques, general models, equations and an estimation of the conversion degree through dynamic, differential and integral methods, as well as particular models for mineralogical components, such as smelter dust and copper concentrates with low and high arsenic content.

May 1, 2012

By A. N. Pritchard

The development of vibrating screens over the last century has seen many variations to suit the exacting requirements of industry. Indeed, as each year passes, industry has presented the challenge to screen manufacturers of supplying larger machines than those used in the past and the question is often posed - what is the maximum limit? Not only must size or screen area be considered but excellence of performance in terms of screening efficiency must be maintained or maximized.

Jan 1, 1983

By T. Braun

In 1911, a young mining engineer named Bartlett Thane assembled a large claim block, 4 miles southeast of Juneau, Alaska. Across the Gastineau Channel on Douglas Island, the Alaska Treadwell Gold Mining Company had, by 1904, produced gold valued at more than three times the purchase price of Alaska in 1867 (Kelly, 2010). Thane knew his deposit was lower grade than other mines or prospects in the area; however, if the deposit was developed on a large-scale, the trend and size of the deposit made the project potentially economic. In 1911, Thane developed a business plan for the project and successfully attracted investor interest. In 1912, Daniel C Jackling visited the property at the request of an east coast investment group. Upon inspection of 5 years of production records for the Perseverance Mine, Jackling saw an opportunity to apply the low-grade/high volume milling technology which was widely adopted to the copper porphyry deposits of the southwestern U.S. With a design capacity of 6,000 tons per day (5,454 tonnes/day), Jackling’s innovative mill design would require high volume underground mining methods and the power of two new hydroelectric projects. By 1915, the Alaska Gastineau Mining Company was in full production. Between 1915 and 1919, the mine and mill set production records for haulage and throughput. The hydroelectric projects proved to be successful engineering marvels. Operational difficulties related to ore grade, refractory elements and labor shortages interrupted production on an increasing basis. In 1921, the mining company permanently shut down operations. INTRODUCTION The Juneau Gold Belt begins at Windham Bay near the southern end of Stephens Passage and extends approximately 100 miles north to Berners Bay (Figure 1). The first large-scale and sustained underground mine, operated by the Alaska Treadwell Gold Mining Company in the late 1880’s, established the Juneau-Douglas area as the regional hub for transportation and development. In the mid-1890’s, the combined population of Juneau and Douglas reached approximately 3,000 residents, largely driven by employment and support demands of several small to mid-size underground gold mines in the region. By 1904, the value of the cumulative gold production of the Alaska Treadwell was five times greater than the purchase price of Alaska in 1867 (Kelly, 2010). By the turn of the 20th century, economic growth in the Juneau-Douglas area relied on supplies delivered from the lower 48. Passenger and freight shipping lines required 3 to 4 days to make the one-way trip from Seattle to Juneau. Established shipping routes required experienced crews due to navigation hazards and adverse weather conditions. Even with precautions at the time, steam ships and freighter vessels experienced breakdowns or encounters with natural hazards that resulted in damage or in some cases, sinking. Interestingly, with no roads or railroads connecting Juneau to other communities in southeast Alaska, Juneau still relies on seaborn shipping in the 21st century.

Jan 1, 2019

By R. J. Matetic, J. Noll, C. Zhou, J. DuCarme, M. Reyes, J. Srednicki

"In April 2016, MSHA began requiring the use of continuous personal dust monitors (cPDMs) to monitor and measure respirable mine dust exposures to underground coal miners. After the cPDM’s implementation, mine operators discovered that it interfered with proximity detection systems (PDSs), thus exposing miners to potential striking and pinning hazards from continuous mining machines. NIOSH was sought out by MSHA and mining industry stakeholders to determine how the cPDM and PDS interact with each other. Accordingly, NIOSH investigated existing standards, developed test protocols, designed experiments, and conducted lab evaluations. Some interferences were observed to be caused by electromagnetic interference (EMI) from the cPDM. Results showed that there was no significant interference when the cPDM and the miner-wearable component of the PDS were separated by distances of 6 inches or greater. In this study, the cPDM and PAD needed to be at least 6 inches apart in order for them to be used simultaneously and reduce interference potential. INTRODUCTION Underground coal miners are exposed to a variety of hazards on a daily basis such as coal dust exposure, high noise levels, roof and rib falls, the potential for fires and explosions, and operating and working with heavy machinery. One of the hazardous jobs is operating or working nearby a continuous mining machine (CMM). According to Mine Safety and Health Administration (MSHA) statistics, 40 miners have been fatally struck or pinned by a CMM since 1984. In an effort to prevent future striking and pinning fatalities from occurring, proximity detection systems have been developed and are required on all operating CMMs in underground coal mines, with the exception of full-face CMMs, by 2018 (1,2). Proximity detection systems (PDSs) are designed to alarm miners and stop machine motion in order to protect miners from being struck, pinned or crushed by CMMs(3). Currently, MSHA-approved PDSs, installed on CMMs, are based on the principle of magnetic flux density (B-field) (4,5). The system generates a magnetic field around a CMM and determines the relative distance a miner is from the CMM based on a detected magnetic flux density. A PDS typically consists of multiple magnetic field generators mounted at different places around the CMM, and personal alarm devices (PADs), which are worn by the miners to detect the magnetic flux density. When a miner, wearing a PAD, gets closer to the machine, the PAD detects a stronger magnetic field from the generators and detects a weaker magnetic field when a miner moves away from the machine. The magnetic field generators installed on CMMs typically produce modulated magnetic wave signals at frequencies between 10 kHz and 120 kHz. The magnetic fields are measured by three small magnetic coil antennas mounted on orthogonal axes inside of the PAD worn by the miner. According to Faraday’s Law, the changing magnetic field induces a voltage in each coil antenna, and the voltage values are transmitted from the PAD back to a controller on the CMM wirelessly, typically at a frequency between 400 MHz and 2.5 GHz. These values are then used to determine the distance between the miner and the generators of the machine. Typically this information is used to determine when a miner wearing a PAD is in a warning zone or stop zone which would trigger different alarms and actions such as slowing the machine down or stopping it."

Jan 1, 2017

By Guy D. Bruno

Through the remainder of this century, world consumption of fluorine per ton of primary aluminum produced will continue to be substantially reduced. Growth of the primary industry will offset some of the unit consumption, but demand for new fluorine sources will decline sharply. Continued application of dry fume scrubbing systems will be the most significant factor in reducing demand.

Jan 1, 1978

By Brent A. Elliott, J. Richard Kyle

Texas is a major producer of industrial mineral resources required by the state’s ever-growing population that now exceeds 28 million. Texas typically ranks in the top three states for the value of non-fuel mineral production with a total value of $5.2 billion in 2017, accounting for 6.9% of the total US mineral value. Almost 90% of current Texas industrial mineral value comes from the production of cement, crushed stone, industrial sand, and construction sand and gravel. Construction material consumption is focused in the 25 metropolitan areas of the state with populations of > 100,000 residents. Industrial mineral consumption is dominated by the four most populous regions of the state—Houston, Dallas-Fort Worth, San Antonio-New Braunfels, and Austin-Round Rock—with an aggregate population of more than 18 million. More than 11,000 employees work in Texas mining and processing operations. Texas produces more crushed stone than any other state from more than 200 quarries; a similar number of operations produce sand and gravel. Specialty industrial sand production for use as proppants in hydraulic fracturing for enhanced petroleum production serves as an excellent example of how developments in one industry sector can markedly affect another industry; the production of industrial sand in Texas has markedly increased over the past decade, reaching $1.3 billion in 2014. With Texas’ population projected to reach 50 million by 2050, continuing in-state development and production of industrial minerals will be required to supply its residential, commercial, and industrial users. Favorable geology and economic factors provide opportunities for identification and development of new industrial mineral production sites.

By M. Peters, P. Schmäh

The development of renewable energies and a sustainable power grid are the challenges for future energy supply. Underground cables will replace the vulnerable overhead lines, because of their safety benefits. Due to the public environmental awareness, smart tunnelling and trenchless solutions are required for inner-city and cross-country installations of underground cables, as well as for crossings and the landfall sections to connect offshore wind farms to the transmission grid. Methods from the tunnelling and pipeline industry provide a high flexibility in the planning of alignments, including versatile tunnel concepts and the installation of protective pipes with E-Power Pipe and Direct Pipe.

Jun 13, 2023

By J. Kemeny, K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in an area of the mine that contains argillite and is relatively homogeneous. This process also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for argillite will be updated as more tests are conducted, and the model will be extended to the four other primary rock types at the Asarco Mission mine.

Jan 1, 2011

By S. W. Cavender

The analysis of the results of metallurgical experiments is often complicated by experimental errors and uncertainty, the complexity of the system being studied, and the confusion of correlation with causation. Consequently, comparative statistics are used to determine if a difference exists between the outcomes of tests, an estimate of this difference, and the precision of the estimate. This paper reviews the use of significance tests and confidence intervals for the comparison of results from two tests, the use of reference distributions, and blocking and randomization techniques to reduce unavoidable sources of variability. These techniques are demonstrated using plant and laboratory data.

Jan 1, 1993

By Omid Asghari, Seyed Reza Ghavami-Riabi, Sajjad Talesh Hosseini

Separation of geochemical anomalies from the background using various methods for identifying areas of higher mineral potential is a critical first step in Greenfield and Brownfield programs. There are several methods for differentiating anomalous regions from the background. The U-spatial statistics is an effective technique that provides the opportunity of reaching this goal by considering the geochemical sample locations in the separation of geochemical anomalies. In this study, a developed form of the U-spatial statistics method is introduced, which not only considers the existence of anisotropic spatial variations in input data but also reduces the computational (CPU) time. While the previous method is based on the isotropic assumption in the study area and a set of search windows at different times, here, the geochemical anomaly is determined by pasting only one ellipsoid window, effectively combining the flexibility of the U-spatial statistics method with the advantages of geostatistical approaches. This paper compares various approaches (the previous and developed version of the U-spatial statistics method, concentrationarea (C–A) fractal model, and probability diagram modeling) for the separation of anomalous areas in the presence of heterogeneous spatial variations. This is done with an application to a Baghqloom porphyry copper deposit located in southeastern Iran. The high potential areas identified via different approaches show an anomalous region in central parts of the Baghqloom area, which partially coincides with an intense potassic alteration area. Compared to other methods, our algorithm separated the high potential areas at a greater spatial resolution.

May 3, 2021

By F. Dingwu

The latest technology and novel equipments in kaolin processing industry in China are described in this paper. Some typical experimental results are presented, which include laboratory-, pilot-or commercial-scale tests. The characteristics of kaolin processing technology are summarized, and the developing trends are indicated.

Jan 1, 1995

By T. Cienski

The paper presents and discusses the results of a detailed study conducted on the subject of energy consumption in the comminution of industrial minerals. The study was based on pilot circuit testing, plant operating data collection, detailed equipment data and literature research. The areas covered by investigations include: high efficiency classification; air classifiers for cement grinding circuits; grinding aids in dry grinding: dry grinding circuit, control based on particle size measurement. Results obtained indicate a large potential for the reduction of energy consumption, in particular in the traditionally high cement clinker grinding circuits. Better classification techniques and correct application of grinding additives can significantly reduce power used per ton of product and also substantially increase grinding circuit output.

Jan 1, 1990