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Zirconium chloride is of great commercial importance as starting materials for production of ZrO2, Zirconium metal and other Zirconium compounds from its main resources (Zircon Sands). The present study concerns with preparation of pure ZrO2 from Zircon by direct chlorination technique. Different parameters affecting the chlorination process are studied viz. carbon, chlorine flow rate temperature and time. The chlorination extent is determined from the loss in weight and chemical analysis of reaction products. The maximum chlorination extent -92% are achieved at 1100°C for 30 min. Zirconium oxide is produced from the collected zirconium tetrachloride either by calcination at 900°C or by hydrolysis in water in presence of RCI with a purity = 99%. Evaluations of the products of the process are investigated microscopically and by X-ray diffraction. The apparent activation energy of the chlorination of Zircon is determined to equal 36 kJ/mole.

Jan 1, 1997

By Robert E. Murray

The title of my paper, "A Company's Response to Federal Coal Leasing," brings to mind a picture of a dog chasing its tail. This is what the coal industry, has been doing since the Federal coal leasing moratorium went into effect in 1971. We've gone around in many circles, but we are only very slowly, if at all, getting closer to catching our tails, i.e., efficient, economical, and rational Federal coal leasing. My companies, The North American Coal Corporation and its four Subsidiaries, The Falkirk and Western Plains Mining Companies and The Coteau and Missouri Valley Properties Companies, together hold in excess of 4.5 billion tons of lignite reserves in North Dakota. Some of our North Dakota properties are substantially interspersed with Federal coal, with the government holding title to the minerals in every other section. This checkerboard pattern of Federal ownership has made it difficult to develop and market some of our reserves, and, as a result, it has become imperative that we be familiar with and active in the Federal Coal Leasing Program.

Jan 1, 1982

By K. Fleck

Energy West Mining Company (EWMC) has implemented a geologic program for improving stability and support requirements along deep two-entry longwall gateroads at its Deer Creek Mine operations located near Huntington, Utah. Together with geotechnical monitoring and concurrent review of mine seismicity in cooperation with MTI staff, it has become possible to improve longwall layout designs for two seam extraction of the Hiawatha and Blind Canyon seams. The geologic program consists of surface and in-mine exploration drilling, surface and in-mine geologic mapping, rock mechanics testing and detailed measurements of changes in depositional and structural conditions during development of every longwall gateroad. The geotechnical program consists of underground measurements at seven locations in two neighboring mining districts located in the Hiawatha and Blind Canyon coal seams under moderate to deep cover. Within the last five years, additional measurements, including data on seismicity and face conditions, have been incorporated into the data collection program for verifying the insitu coal strength and load transfer mechanisms for improving two-seam designs and support systems. Geologic mapping results are also used to predict local stability of headgate and tailgate entries, combining mine roof mapping, stratigraphic profiles of the coal and roof, and depth-of-cover information and dual-seam mine overlays, for use by operations personnel in planning roof and rib support for the retreating longwall sections.

Jan 1, 2012

By Bekta? Uz

In this research, geological characteristics of sand quarries around the village, Kemerburgaz Akpinar, are studied and the mineralogical, petrographical, chemical and technological characteristics (such as sieve analysis, relative density, water absorbtion etc.) of the sand samples, obtained from the area are explained. In the general area sand' quarries, being in lacustrine formations belonging to Neogen, the stratigraphic location of the sand occurences take place at high levels of these formations, geologically. All of this pattern, being under 1 mm with a ,particle dimension, it ranges from 0,5 mm in the quantity of 99 % to 0,25 mm in the quantity of 15 relative density is 2,65 g/cm3 ; water absorbtion is 0,9%. Mineralogically, the sand samples contain Quartz (84%), Feldspar (3%), Calcite + Aragonite (10%), Pyroxen+Amphibole (1-2%), Garnet+Tourmaline (0.5%), Olivine (0.1-0.5%). Besides, sand samples contain SiO2 with the quantity of above 90%. Containing Quartz at high levels for mineralogical, petrographical and chemical characteristics, Akpinar sand will be evaluated as silica sand when the carbonate mineral is removed with the method of ore preparation such as leaching.

Jan 1, 2005

By S. C. Sun

Very little information is available concerning the magnetic properties of minerals and only recently has there been any attempt to correlate magnetic susceptibility with varying chemical composition1. The work described here covers a study of the relationship and chemical composition of both the rutile and sphene types of titanium minerals. The relationship between the magnetic susceptibility of three selected mineral specimens and the applied field strength is also presented. Experimental: The equipment and procedures used in this in- vestigation for crushing and cleaning the mineral specimens and for determining the magnetic susceptibilities were the same as that employed by Spokes and Mitchell1. The particle size of-the measured specimens was limited to 270/325 mesh.

Jan 1, 1959

By Yi Luo, FENGLIANG WU

Explosions and fires originated from longwall gob due to the formation of methane-air mixture have been a severe threat to coal miner’s lives.Many numerical studies on coalmine fire and explosion hazards have focused on the airflow in roadways and mine gobs. However, most of these studies isolate the gob from its surrounding roadways, and the network analysis and the CFD method are applied independently tomodel the two classes of airflows. This approach greatly limits the ability of simulatingmine ventilation flow, especially unable to consider the effects of gob boundary conditions on air exchange between the gob and the surrounding airways. An innovative finite tube method (FTM) is developed to couple the one-dimensional mine ventilation network (MVN) and the 2D/3D gob flow field (GFF). In FTM, GFF is discretized into a finite number of flow tubes each of which is formed by any two adjacent stream lines. These tubes, representing the gob’s field flow, connect the MVN into a new coupling network. To solve the coupling model betweenMVN and GFF, an iterative solution technique is developed inwhich the MVN analysis is used to evaluate the boundary pressures for GFF simulation and in turn the FTM feeds the GFF results back to the coupling network. Based on the FTM approach, a model for gas migration in gob has been established for delineating the hazard zones of explosive methane concentration and spontaneous combustion. A computer program is developed to implement the FTM simulation. An illustrative example with five flow tubes representing the GFF is created to verify the stability and convergence of the FTM solution process. A simulation example also indicates that the accuracy of FTM is improved by 12% compared with previous method. Results of an application case show that the program is capable of quantitatively evaluating the gob’s risk zones prone for spontaneous combustion and gas explosion as well as performing risk analysis for various ventilation scenarios.

Jul 10, 2020

By Brendan Demich, Joseph McGuire, Emily J. Haas

Near misses recorded and reported by workers can provide awarenessto the potential causes of injury and prompt safety management initiatives. Although most companies require near-miss reporting, it is unclear what the value of these reports are, if any, and how they influence subsequent actions or controls to reduce on-the-job risks. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a case study with an aggregates company in which near-miss reports were analyzed at each of their locations over an entire quarter during the summer of 2018. Within that quarter, workers recorded 249 near misses. Of those, 167 were valid near misses that occurred at work. Researchers coded the reports using a qualitative 5 × 5 risk matrix. Of the 167 near misses, 19% were deemed low risk, 25% moderate risk, 30% high risk, and 26% critical risk. Several patterns in the near-miss incidents were documented, including classification of incidents and common corrective actions referenced (i.e., elimination/substitution, engineering control or redesign, work process/procedures, and personal protective equipment). The analysis provides insight into ways that risk communication and management programs can be improved to reengage workers and their situational awareness on the job.

By D. Blackwell, W. R. Reed, G. Ross, S. Peters, M. Shahan

Dust collectors for roof bolting machines generally use a dry box to collect the roof bolting material. Recently, an underground mining operation converted a dry box dust collector to a wet box dust collector with a unique exception from MSHA for testing purposes.Water is routed to the roof bolter fromthe main water line of the continuous miner. The wet box utilizes a water spray to wet the incoming material. Testing was conducted comparing the two different collector types. Respirable dust concentrations surrounding the roof bolter with the different collection boxes were similar. The main difference in respirable dust concentrations occurred when cleaning the dust boxes. The average respirable dust concentration during cleaning of the wet box was 0.475 mg/ m3, and during the cleaning of the dry box, the average respirable dust concentration was 1.188 mg/m3, a 60% reduction in respirable dust concentration. The quartz content of the roofmaterialwas high, ranging from 28.9 to 52.7%during this study. The results from this study indicate that using the wet box as a collector reduced exposure to respirable dust up to 60% when cleaning the collector boxes.

Aug 26, 2020

By Sakai Kunito, Nigel B. Sugden

If an Earth Pressure Balance (EPB) TBM is operated effectively tunneling can be carried out producing negligible ground movements. Using the methods given in this paper face losses of the order of 0.5% and less are generally obtainable using an EPB. Operating the EPB TBM in this manner reduces the requirement for the building protection measures used to protect surface structures. This can result in a considerable cost saving for the construction of a tunnel under built up areas. This paper to give guidance on the causes of ground movements around a TBM and the methods of running an EPB TBM that will minimize those movements. Details of how this was successfully done during the construction of the Bangkok Metro are given. The paper is split into three parts as below. 1.Causes of ground movements due to TBM tunneling 2.Methods of controlling those movements using an EPB TBM 3.Case history Bangkok Metro (water main)

Jan 1, 2001

By Yuemin Zhao, Daniel Tao, Xinxi Zhang, Qingru Chen, Maoming Fan, Zhenfu Luo, Xiuxiang Tao, Guohua Yang

Coal is currently cleaned with the minimum of size reduction, fine particle processing, recovery, and tailings disposal are major problems. Adequate water resources are not always available. For example, two thirds of China's coal is located in arid areas. Hence, dry separation provides an alternative approach. Of the dry coal separation methods available, air dense-medium fluidized beds have been used to separate 50~6mm coal efficiently. However, excessive bubbling and back mixing of the separated solids in the air-dense media fluidized bed causes the high lower size limit of 6mm for the feed material, this affecting the preparation efficiency. Based on prior study on air-fluidized dense media for 6~50mm coal preparation, this paper presents methods and test results on the fine coal dry classification, static electricity beneficiation of 0~0.5mm coal, and magnetically stabilized fluidized beds for separating 0.5~6mm coal.

Jan 1, 2005

By M. L. Free, N. Dhawan, M. S. Safarzadeh, J. D. Miller, M. S. Moats

"The drum agglomeration of nickel laterite and gold ores has been optimized through the design of experiments (DOE) using a Taguchi L16 (45) orthogonal array to determine the optimum conditions for maximizing average agglomerate size and minimizing the amount of fines. The effects of controllable operating factors including moisture content (nickel laterite ore: 34-37%; gold ore: 7-10%), retention time (2-3.5 min), drum speed (15-45% critical speed), drum load (nickel laterite ore: 8-32 %; gold ore: 6-22%) and acid concentration (150-600 g/L) on the performance of the agglomeration process were studied.For nickel laterite ore, maximum average agglomerate size and minimum percent fines (-1 mm) occurred under the following conditions: drum load (23.7%), moisture (36.5%), time (3 min), drum speed (30% critical speed) and acid concentration (150 g/L). Under the studied nickel laterite ore conditions, the most effective parameters for maximizing average agglomerate size and minimizing the amount of fines were found to be drum load and acid concentration, respectively. Drum speed had a statistically significant effect on minimizing the amount of fines. Maximum average agglomerate size and minimum percent fines (-1 mm) for gold ore occurred under the following conditions: drum load (19.3%), moisture (8.5%), time (2 min 15 s) and drum speed (40% critical). The most significant factors for maximizing average agglomerate size and minimizing the amount of fines for gold ore were found to be drum load, time and moisture.IntroductionSeveral heap leach operations have experienced problems in terms of poor recovery due to percolation issues caused by low-grade complex ores, tailings and clayey deposits. Poor percolation can lead to low metal extraction due to solution channeling or the development of impermeable/dead zones within the heap (Dhawan et al., 2012; Kappes, 2005). Improper heap building practices such as the use of loose agglomerates and inadequate attention toward the presence of clay minerals have been among the main reasons for percolation issues. During the transport of ore material, severe segregation of the material can occur. To overcome percolation problems, a major improvement was made through the introduction of agglomeration prior to ore placement. If the ore particles and agglomerates are of similar size, segregation can be avoided to a great extent (Dhawan et al., 2013; Kinard and Schweizer, 1987; McClelland and van Zyl, 1988). Agglomeration improves the uniform percolation of solution through ore heaps and is applicable to many ores, wastes and milled tailings (Bouffard, 2005; Dhawan et al., 2013). Manning and Kappes (2005) reported agglomeration/ stacking accounts for ~14% of the total heap leaching operating cost. The cost of binder is a primary contributor toward the total cost. Also, the lack of consistent quality control tests for agglomerate often leads to operational problems. The details are mentioned elsewhere (Dhawan et al., 2013). Considering the significant contribution of the agglomeration/stacking step toward the total heap leach operating cost, it is appropriate to study the agglomeration behavior and its optimization for two different ores. The reason to study the same parameters for different ores is the fact that significant variability in the agglomeration behavior of different ores has been reported to exist in industrial operations."

Jan 1, 2015

By K. Norrena

Grade control in open pit mining requires the specification of dig limits that account for mineral grades, economic costs, and selectivity of mining equipment. Visual identification of ore rock types is ideal, but this is not always possible in lower grade disseminated deposits where ore/waste contacts are not visually discernible. In this case, conventional grade control practice consists of a two-step procedure (1) create a map of mineral grades at some selective mining unit scale, and (2) determine practical ore-waste boundaries or dig limits on the basis of the gridded block grades or assay information. This procedure is laborious, depends on a subjective assessment of where the boundary should be, and may be economically sub-optimal. We pose the determination of dig limits as an optimization problem and solve that problem with the technique of simulated annealing. Simulated annealing has the unique advantage of being able to combine multiple non-linear constraints into a single objective function. We use maximum profitability and the ability of the equipment to mine the proposed dig limits as constraints in the determination of optimal dig limits. We require a map of expected profit for eah block. Geostatistical techniques are recommended, for mapping expected profit but not necessary. Geostatistics will provide a quantification of the uncertainty in the grades within rock types using all available blasthole samples and exploration drilling. Some variant of L-optimal estimation or kriging can be used to determine the block-by-block classification that is economically optimum. We also need the expected profit for each block. It is unrealistic to assume free selection, that is, each block cannot be extracted independently of its neighbors. The optimal balance of ''accepting dilution'' and ''wasting ore'' is achieved to maximize profit subject to equipment constraints.

Jan 1, 2001

By X. X. Shao

Dewatering of ultra-fine clean coal slurry to a low moisture level of20 percent is difficult using the conventional techniques. A novel approach, which utilized mixing of fibrous waste material, such as paper, carpet and wood, with coal slurry prior to dewatering was developed. It was found that addition of about 10 Kg/t of carpet fibers or 5 Kg/t of raw paper pulp lowered the filter cake moisture from 22.5 to 18 percent. The compressive strength of the filter cake improved from 0 to 4.5 Kglcm2 and impact resistance from 0 to 4. The experimental data indicated that the handling character of the dewatered fine coal was improved significantly.

Jan 1, 1998

By T. A. Vivian

The use of heavy media organic solvents to recover coal from its attendant gangue is hardly new. DuPont built a pilot plant using pentachloroethane in 1936 at Weston Coal Company, Weston Breaker, Shenandoah, Pennsylvania. That's almost half a century ago. Since that time, it has become common practice to utilize similar classes of chemicals in laboratory separations of coal samples. It is the objective of this paper to discuss some specific separations on both pilot and laboratory scale on samples representing different classifications of coal. These separations have been carried out on coarse (+4 M), middling (4 x 20 M), and fine (-20 M) coal samples. The coal samples tested include Pennsylvania anthracite; Pennsylvania, Indiana and Colorado bituminous; Wyoming sub-bituminous; and Texas lignite. Other chlorinated solvents were used to vary the specific gravity of separation.

Jan 1, 1984

By D. Hopkins, D. Türler, R. D. Giauque, W. B. Davis, M. Karaca

In a highly collaborative research and development project with mining and university partners, sensors and data-analysis tools are being developed for rock-mass characterization and real-time measurement of mineral content. Determining mineralogy prior to mucking in an open-pit mine is important for routing the material to the appropriate processing stream. A possible alternative to lab assay of dust and cuttings obtained from drill holes is continuous on-line sampling and real-time x-ray fluorescence (XRF) spectroscopy. Results presented demonstrate that statistical analyses combined with XRF data can be employed to identify minerals and, possibly, different rock types. The objective is to create a detailed three-dimensional mineralogical map in real time that would improve downstream process efficiency.

Jan 1, 2002

By R. E. Mclvor

This is an update of an original dissertation on this topic by Lavallee, McIvor and Stolovitch (1992). A step-by-step, technical procedure used to measure and improve the performance of plant grinding circuits was adapted into a training program. ?Systematic Design of Instruction? was applied to: ? Determine if training was a suitable way to deliver this new technology; ? Define the technical content of the program; ? Select program specifications based on learner and context characteristics; ? Design, create and test prototypes of the training modules; and, ? Establish a process for plant implementation. The training program covers numerous skills that are extremely valuable for plant personnel, not only in the grinding area, but also for many other parts of the plant. This paper describes how new skills are brought into the workplace through designed instruction can be an effective alternative to hiring during severe skilled labor shortages.

Jan 1, 2008

By H. K. Lin

The free-milling ore characteristics of the Fort Knox gold deposit are ideal for studying gold and silver behaviors in various processing circuits without serious interference of sulfide minerals and other refractory factors. A galvanic effect leads to faster silver dissolution than gold dissolution and, as a result, the Au/Ag solution concentration ratio increases through the leach circuit. In the CIP circuit, Au adsorption is more effective than Ag adsorption. The Au/Ag solution concentration ratio decreases from 10.0 to 1.0 as the slurry advances from CIP tank #1 to CIP tank #5, while Au/Ag ratio in the carbon increases from 3.2 to 15.3, as the carbon advances from CIP tank #5 to CIP tank #1. Silver is stripped more effectively than gold from the loaded carbon. The Au/Ag ratio in solution reaches 2.0 in the first 75,700 L of strip solution that pass through the loaded carbon; as the stripping process continues, the Au/Ag ratio in the strip solution increases. In the electrowinning circuit, the Au/Ag ratio in the spent electrowinning solution is significantly lower than that in the electrowinning feed, indicating that Au is more rapidly deposited onto the cathode than Ag.

Jan 1, 2010

By Y. Paul Chugh

NIOSH and the Illinois Clean Coal Institute are funding studies on characterization of coal and quartz dust in Interior Basin mines since 2009. Coal dust characteristics vary significantly and, are vital for the development of the engineering controls. This paper presents wettability characteristics of coal dust with respect to its chemical and physical properties, since wettability is considered to be a primary dust control technique. Particle size distribution, inter-particle interactions during wetting and quartz associations with organic and inorganic matter in coal seams is critical for understanding wetting phenomena. Silica content in the un-wetted fractions was found to be very high during wetting tests. Wetting of quartz may be limited by its association to hydrophobic materials as well as buoyancy forces resulting from particle size characteristics and particle-particle interaction in the wetting agent. Temperature of the wetting solution and effective contact time between dust particles and water droplets are found to be two important variables affecting the wettability. The characterization data obtained from this study can be utilized to develop engineering controls.

Jan 1, 2011

By A. López-Valdivieso, M. A. Corona-Arroyo, M. Llamas-Bueno

Magnetite (Fe3O4) ore is concentrated by low-magnetic-field drums to recover a magnetite concentrate that is low in silica (SiO2). The presence of SiO2 in the magnetite concentrate for steel production increases the steel processing costs, so a major challenge in magnetic concentration is to lower the SiO2 grade in the Fe concentrate. This work presents studies that were carried out on the removal of SiO2 from the magnetite concentration at the plant scale. Studies were performed with a three 36 × 96″ drum unit processing 46 ton/h of rougher magnetite concentrate. These studies showed that silica appears in the magnetite concentrate by three mechanisms, namely SiO2 entrainment in Fe3O4 chains, heterocoagulation between Fe3O4 and SiO2 particles, and mineral locking of SiO2 to Fe3O4. The SiO2 entrainment mechanism had the highest contribution (75%) to the SiO2 recovered in the Fe concentrate. Electrokinetic studies on Fe3O4 and SiO2 showed that heterocoagulation occurs because of the low negative zeta potential of the minerals at the pH of the plant slurry. This study also showed that a high percentage of ultrafine size SiO2 particles trapped in Fe3O4 agglomerates was not removed by the dilution water for the slurry fed to the drum. To lower the SiO2 recovery in the drum magnetic concentration process, work should be directed towards the removal of trapped SiO2 in Fe3O4 agglomerates.

By R. L. Brown

The Buchans mining district is located roughly at the center of the island of Newfoundland and contains some 18 separate mineral deposits. The first of these deposits was discovered in 1905, the latest discovery having been made in 1979. To the present (1983), some 16 Mt (17.7 million st) grading 1.33% Cu, 7.5% Pb, 14.5% Zn, 115 g/ t (3.7 oz per ton) Ag, and 1.4 g/t (0.04 oz per ton) Au have been mined. Mining operations are now largely terminated, but a few hundred thousand tons of economically marginal reserves may be mined in a salvage operation. The Geological Association of Canada Special Paper No. 22, "The Buchans Orebodies, 50 years of Mining and Exploration," contains papers which describe the history, geology, and the application of evolving geological concepts in exploration. Papers by Neary, Swanson, and Thurlow and Swanson in that volume are topical to the present discussion. Successful exploration techniques at Buchans included physical prospecting, utilization of the state-of-the-art geophysical techniques, saturation diamond drilling which was made possible by the high gross value of the existing ore, and, since 1955, diamond drilling directed by fairly well understood geological parameters. The record of discovery started in 1905 when the Buchans River deposit was found by Matty Mitchell, a prospector employed by the Anglo- Newfoundland Development Co., a British company which owned mineral rights over a very large area in the Red Indian Lake-Exploits River drainage system.

Jan 1, 1991