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By A. G. Fabbri

This paper aims at the application of quantitative criteria for evaluating the mineral potential of square cells representing areas in terrains being explored at a reconnaissance level. The assumption is made here that the evaluation methods used by an expert economic geologist can be organized into geological models for establishing associations within imaged areas, that correspond to pixels with similar characteristics. UTM-registered multiple data sets have been constructed which include seasonal LANDSAT 2 and 4 images, SEASAT scenes, selected airborne radar images, digitized aeromagnetic, gravity, bedrock geology and topographic elevation maps. The area of interest is located in the Bathurst Inlet, District of MacKenzie, N.W.T., where a preliminary mineral potential evaluation was performed by the Geological Survey of Canada to assess its suitability for a national park. The multiple data sets described in this paper can be used for many studies at different resolutions, for comparing processing methods in remote sensing and, most importantly, for evaluating the physical and spatial relationships between the different images in registered data sets.

Jan 1, 1989

By Lana Alagha, Fardis Nakhaei, Jose L. Corchado-Albelo, Noelia Munoz-Garcia, Michèle Heitz

Sulfide tailings from past and present mining activities are important hosts of critical elements and precious metals. This review paper presented a literature survey on the recovery practices of some critical minerals containing Te from sulfide tailings with a special focus on the physical beneficiation and hydrometallurgical separation methods. Finally, a conceptual framework and possible processing flowsheets were proposed. The findings of this review will be useful for the researchers in the field of geochemistry, mineral processing, and metallurgy to evaluate the separation processes for reprocessing of mine tailings for the recovery of critical minerals.

Feb 1, 2024

By A. M. Galperin

Back analysis is a very important procedure for proper understanding of physical processes. Back analysis can be used to establish the role of different factors, define parameters to be calculated and formulate the behavior of natural or physical processes based on field experimental results. It is evident that, in order to obtain the necessary data for back analysis, field observations are required. For the Michailovsky region (Kursk Magnetic Anomaly, KMA) the long-term strength characteristics of the clay covering the quarry slopes were established with the help of back landslide calculations. The obtained data allowed quantification of the shearing resistance parameters at the presence or absence of intermittent dips of discharge in the pit bank massif structures. Based on the results of investigation for material composition, strength and deformation of finely dispersed (clay-chalk) deposits in the Kursk Magnetic Anomaly including measuring of the settlements of filled structures, complex probing and laboratory determination of water-physical and mechanical properties of "man-made" soils, engineering-geological zoning of filled structures was carried out.

Jan 1, 2005

By Yuexin Han, Yanjun Li, Peng Gao, Yongsheng Sun, Qiang Zhang

The non-isothermal magnetization roasting process and isothermal magnetization roasting process of siderite ore were investigated using thermogravimetric (TG) analysis and a real-time infrared gas analyzer. X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) were used to analyze the characteristics of samples. The results showed that the decomposition degree and decomposition rate of siderite ore were vitally affected by heating rate and roasting temperature. It was determined that A1 reaction model (f(α) = 1 − α) and A3/2 reaction model (f(α) = (3/2)(1 − α)[−ln(1 − α)]1/2) were the most probable mechanism function of the non-isothermal decomposition process and isothermal decomposition process, respectively. The phase transformation and decomposition mechanism during the roasting process were evaluated. Siderite decomposed in the process of magnetization roasting, released CO and CO2, and transformed into strongly magnetic magnetite. The SEM images highlighted that as the decomposition progressed, the structure of roasted samples was destroyed, and an increasing number of cracks and pores emerged on the surface, which is advantageous to the following grinding process.

Mar 26, 2021

By David R. Delling

Introduction In 1967, Tenneco acquired Kern County Land Co. The primary reason for the acquisition was to obtain Kern's agricultural, manufacturing, and oil interests. Included in the Kern portfolio were the core of Tenneco's present sodium leases in Sweetwater County, WY. This lease base has been ex¬panded and now consists of 62 km2 (24 sq miles). Beneath this property lies more than 500 Mt (550 million st) of economic trona ore. Following the Kern acquisition, Tenneco continued exploration and feasibility studies concerning the trona leases. The effort was accelerated in 1976. Tenneco was attracted to trona because of the favorable lease position it held, the growth rate of the Wyoming industry during the 1960s and 1970s, and the prospects for a long-term, stable business enterprise. The reserve picture was certainly attractive to a company long accustomed to the never-ending struggle to replace oil and gas reserves. In 1978, Wyoming was a boom area that had experienced rapid growth for a number of years. Unemployment was very low and vacant housing nonexistent. The prospects for soda ash were somewhat different in the 1970s than now. But it was recognized even then that a new producer would have a challenging task to compete in this business. Tenneco knew the capital burden required to build a grassroots facility during inflationary time, would have to be offset elsewhere Since labor and energy are the dominant direct costs in mining trona and producing soda ash these factors have always received a great deal of attention. Contracting and permits Environmental monitoring on the site began in late 1977. With the already mentioned considerations in mind, engineering began by mid-1978. Brown & Root Inc. was selected as the general contractor for the project. S. A. Scott & Co. was the engineering subcontractor for the mine shafts, hoists, ventilation system, and miscellaneous mine facilities. Frontier-Kemper was awarded the contract for sinking the two mine shafts. Acquisition of numerous federal, state, and local permits occupied all of 1978 and 1979. The Wyoming Industrial Siting Permit, which addresses socioeconomic issues, drew the most public interest. Siting issues were all satisfactorily resolved by negotiating reasonable stipulations with various local governmental units, school districts, and the like. Site location The Green River project location is not truly remote. It is located within 5 km (3 miles) of Interstate 80 and only about 32 km (20 miles) west of the city of Green River. Nevertheless, a substantial investment had to be made in communication and utility links to the site. These included: • A 14-km (8.5-mile) rail spur connecting with the Union Pacific Railroad at Bryan, WY. This spur has four bridge structures including one crossing Interstate 80. Most soda ash is shipped by rail, and coal is received over this line as well. • A paved 5-km (3-mile) roadway connecting to Interstate 80. • A powerline extension of about 27 km (16.5 miles), along with two new substations. • A 24-km (15-mile) waterline connecting the plant to a pump station on the Green River. The site is located on gently sloping terrain at an elevation of about 2.1 km (6800 ft). Ground conditions are good for construction. Weathered bedrock lies near the surface in most places. Geology The general geology of the Green River Basin has been well described previously. Tenneco's ore is in several superimposed evaporate beds. But the bulk of it is present in Bed 17, located about 457 m

Jan 10, 1985

By Roshan B. Bhappu

Based on the classical definition of optimization, flotation plants of today are far from being perfect, effective, or functional as possible. Though considerable efforts have been expanded in the optimization endeavor during the last decade, much more needs to be done in the future to optimize our flotation plants and operations. The major problem in designing an optimum flotation circuit is that the flotation process depends on the interaction of several physical and chemical parameters. In the past, there has been a tendency to only consider the effects of chemical factors such as flotation reagents: collectors, frothers, conditioning reagents, pH, etc. On the physical side, the emphasis has been limited to the liberation characteristics, grinding time, percent, solids in the pulp and flotation time. Its only recently that we are employing particle size analyses, on-stream analysis, oxidation reduction potential and the like, as operating controls. The design, operation and control of a mineral processing plant depends on costs incurred at all stages, from inception (testing for flowsheet development) through plant closure and beyond. To ensure that micro- and macro- engineering technology is transferred to operational levels, the academia, testing engineers, designers, operators, consultants and management must all get involved in the transformation process. Historically, in the 1950’s engineering empiricism was strengthened through micro-engineering based on fundamental and mechanism. Unique scientific apparatus such as zeta meter and infrasizer were used to test new hypotheses. With the advent of computers in the 60s and 70s, complex differential equations were solved to study and understand unit processes and to assess mechanism assumptions. Such efforts contributed to improved understanding of the unit operations such as comminution, flotation, thickening, filtration and the like. In the 80s and 90s with the availability of more sophisticated computer technology involving modeling procedures, advanced numerical methods, image analysis, nonlinear-curve-fitting and data adjustments, it was possible to test newly developed models under the production environments. These innovations are now available to develop simulator and sensors (such as particle size analyses) for macro-engineering purposes including plant design, automatic controls and optimization. Accordingly, it behooves the mining companies and plant operators to take advantage of these new developments to control a large number of physical and chemical parameters involved in the plant operation and optimization. This is especially important in light of declining head grades and increasing operating costs in the U.S. minerals industry if it wishes to maintain a competitive edge in the international marketplace. In regard to the future R & D activities in the field, in order to arrive at useful correlations in micro- engineering research, it is essential to consider a plant operation as an interactive engineering system representing the combined effects of physics and chemistry, equipment and operation. The important issues that needs to be addressed in the future are

Jan 1, 1993

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 Clyde M. Pearce

This paper describes the facilities at Pointe Noire, Quebec that Wabush Mines utilizes for the receipt, distribution, stockpiling and shipping of iron ore concentrate and pellets. The main topics to be covered will be: 1. - General description 2. - Concentrate receiving facilities 3. - Conveying circuits 4. - Stockpiling 5. - Vessel loading GENERAL DESCRIPTION The map of the eastern Quebec - western Labrador area as shown in Appendix #1 shows the location of Wabush Mines properties. You will note the Scully Mine located at Wabush Lake, Labrador, 235 miles north of the town of Sept-Iles, Quebec. Our neighbors, the Iron Ore Company of Canada have their properties further north at Shefferville, near by at Carol Lake and at Sept-Iles. To the Southwest, our other neighbors, Quebec Cartier Mining, have their iron ore processing facilities and their terminus on the St-Lawrence at Port Cartier. Concentrates are prepared at the scully Mine by mining, crushing, grinding, concentrating, drying and high tension separation for shipment by rail to Pointe Noire, Quebec. Pointe Noire is situated across the bay from the town of Sept-Iles, Quebec on the North Shore of the St-Lawrence River. The concentrate consists of 66% iron, 2 ¼ percent silica and practically no moisture, permitting the use of specially constructed railroad cars and handling facilities to convert the concentrate into pellets, the final product.

Jan 1, 1967

By B. E. Davis

A problem that has continued to plague the Florida phosphate industry is the loss of coarse phosphate in the flotation circuit. Attempts to remedy this problem such as floating the coarse material (plus 425 µ m) in a separate circuit have resulted in limited success, but recovery is still not optimum. The Bureau of Mines is investigating ways to improve the recovery of coarse phosphate through improvements in the conditioning step. Studies to optimize conditioning parameters such as agitation energy, conditioning time, conditioner solids, and residual clay content have resulted in improved P2O5 recovery. Optimizing these and other conditioning parameters resulted in a rougher concentrate grading 30 pct P2O5 with a P2O5 recovery of 97 pct.

Jan 1, 1993

By Brian Heer, David Young, Randall Essex

The Manapouri Power Station is New Zealand’s largest hydroelectric facility located on the South Island of New Zealand. Constructed in the 1960’s, it includes a 700 MW under-ground power station and a 9.8 km (6.1 mile), 9.2 m (30 ft) diameter tailrace tunnel. The output of the power station is currently limited due to excessive head losses in the tailrace tunnel. To remedy this situation, the Electricity Corporation of New Zealand (ECNZ) retained Woodward-Clyde to design a second tailrace tunnel and appurtenant facilities and prepare Contract Documents for construction. The Project will involve the construction of a 9.8 km(6.1 miles), 10 m (33 ft) diameter, TBM-mined tunnel, hydraulic control structures at the upstream and downstream ends of the tunnel, an underground dewatering shaft and station, and tailrace channel improvements. This paper summarizes the key design and construction issues addressed during the planning and design phases, outlines the risk management provisions incorporated in the Contract, and overviews the Interactive Tender Process (ITP)that was implemented during the pre-tendering and tendering periods.

Jan 1, 1997

By William R. Yernberg

The combined 78th Annual Minnesota Section of SME Meeting and 66th Annual University of Minnesota Mining Symposium was held April 19 and 20, 2005, in Duluth, MN. More than 300 mining professionals, including engineers, executives, mining managers and suppliers, from throughout the United States and eastern Canada attended the meeting. This year’s theme was “Global Demand: A Window of Opportunity.” The meeting included a keynote address, technical presentations and a trade show. The atmosphere at this year’s meeting was upbeat. The iron ore mining industry in Minnesota is experiencing one of its biggest turnarounds in history. Because of greater demand, iron ore prices increased 20 percent during 2004 and 71.5 percent so far in 2005.

Jan 1, 2005

By R. Poulin, R. Pakalnis, D. Peterson

Introduction A comprehensive project has been completed at the University of British Columbia that focused on the development of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. The project began in 1989 under the sponsorship of HDRK Ltd., a consortium of mining companies including Inco, Noranda and Falconbridge Ltd. The objective was to develop a cuttable cable bolt that would serve as support for a continuous miner within a hardrock environment (Mah, 1994). The bolt was required to be cuttable by a continuous roadheader without adverse effects to equipment, personnel and the milling process. From the beginning, the focus was to employ existing cable bolt installation technology (Goris et al., 1994) whereby the cable bolts are grouted within a 4.8-cm-diam (1.08-in.diam) or larger employing a portland cement grout having a water: cement ratio between 0.35:1 to 0.4:1. The prototype, developed from Phase I, was technically comparable to that of conventional steel cable bolts. However, high cost and limited accessibility hindered its commercial acceptance. The second phase of the project was sponsored by the British Columbia Science Council and Pacific Pultrusions Ltd. of British Columbia to locally develop a glass fiber cable bolt. This phase of the project has resulted in the DAPPAM cable bolt (Pakalnis et al., 1994). DAPPAM Cable bolts are the second most used support method in Canadian underground mines after mechanical rock bolts. It is projected that 870,000 m (2.9 million ft) of cable bolts are installed annually in Canada (Poulin et al, 1994). The objective of the research program was to develop a glass fiber cable bolt with similar pullout strengths to the conventional steel cable bolts (267 kN - 60,000 lbf). More than 200 laboratory pull tests were conducted employing standard cable bolt test procedures, as outlined by the US Bureau of Mines (Goris, 1994), to assess optimum rod and surface composition, geometry, number required, pullout and shear characteristics, among others. This resulted in the DAPPAM cable bolt (Fig. 1). It consists of 10 individual 0.6cm-diam (0.25-in.-diam) rods enveloping a 2.2-cm (0.8-in.) outside diameter, high-density polyvinyl grout tube. The composite used in the construction of the rods is comprised of about 65% glass fiber within a 35% polyester resin matrix (by volume). Through pultrusion (a continuous fabrication technique), the fibers and resin are combined into a composite material. The strength of the overall composite is largely governed by the material properties, the alignment [ ] of the fibers relative to the applied load and the density and interaction of the overall components within the composite. A further modification to the composite was the addition of a sand grit to the surface of the individual rod. This increased the overall bond strength between the rod and the cement-based grout, used to solidify the cable bolt to the rock mass. The grout tube has an inside diameter of 1.9 cm (0.75 in.) and is rated at a pressure of 1.72 MPa (250 psi). During installation, the grout is pumped through the annulus of the grout tube thereby filling the hole from toe to collar. Laboratory and field trials concluded that a minimum drill hole diameter of 4.8 cm (1.08 in.) be used to ensure optimum grout coverage. Table 1 compares the design strengths (as tested) for DAPPAM vs. the ultimate strengths for a conventional 1.6cm (0.6-in.) steel cable bolt. The characteristics for the steel cable have been derived directly or indirectly by Goris et al. (1994). A design tensile strength of 289 kN (65,000 lbf) was proposed for the composite developed. However, recent tests have indicated maximum breaking strengths of more than 400 kN (90,000 lbf) (Fig. 2). Figure 2 shows the load vs. displacement pull out curves for steel and DAPPAM cable bolts. The methods of testing were standardized so as to be able to compare the results directly. The shear strength of the fiberglass cable is largely a function of the surface area sheared. Shear strengths of 89 kN (20,045 lbf) were obtained for the configuration shown in Fig. 1 when sheared normal to the axis of the cable. The testing procedure was similar to the shear tests performed on steel by Goris (1993). It is important to reinforce the implication that critical bond strength has on the success of an overall support system.

Jan 1, 1995

By Jaeheon Lee, Jai‑Won Byeon, Junmo Ahn, Jun‑Jae Lee, Eun‑Woo Kim, Yoo‑Jin Kim, Jiajia Wu, Jae‑Yeon Kim

Growing demand for valuable battery materials and environmental issues from battery disposal make the recycling of spent lithium-ion batteries (LIBs) essential. Specifically, the green approaches using organic reagents have garnered many attentions for battery recycling. In this study, a synergetic organic leaching system using methanesulfonic acid (MSA) of strong organic acid and citric acid (CA) with good chelating ability was investigated to extract valuable metals from LiCoO2. Hydrogen peroxide was used as a reducing agent to enhance leaching kinetics. Cobalt extraction of 98% and lithium extraction of 97 % were achieved in the optimized condition; 2.4M MSA, 1.6M CA, 1.0 vol% H2O2, S/L ratio 80 g/L, 85 °C, and 1 h. The optimal leaching condition of the MSA-CA mixed leaching system exhibited good applicability to various cathode scraps, such as LiCoO2, LiNixMnyCo1- x-yO2, and LiNixCoyO2. The dissolved Co and Li ions in the MSA-CA leachate were selectively recovered with high recovery efficiencies of 99 % and 97 % as Co3O4 and Li3PO4, respectively. The recovered Co3O4 and Li3PO4 were utilized to regenerate cathode materials. LiCoO2 and LiFePO4 were also synthesized through a solid-state reaction and hydrothermal method. The recycling process based on the MSA-CA-H2O2 synergetic leaching system was proposed, and it might be applied as a green and economical organic leaching system for the recycling of various types of spent LIBs.

Sep 20, 2023

By Matthew Price, Laura Brown, Atulya Verma, Samantha Espley

Burst-prone conditions are a significant hazard in deep hardrock mines, elevating the risk to excavation stability and, more importantly, to worker safety. As mining progresses deeper, induced stress changes may trigger the initiation of rock failure processes which can be detected and recorded as mine seismicity. The implementation of seismic monitoring and routine seismic data analyses enables mine seismicity to be quantified spatially, temporally and on scale. The ability to quantify and characterize mine seismicity offers the opportunity to gauge seismic hazard, identifying high risk zones for mitigation against burst-prone excavation failure. Over the last decade, the Mines Technical Services (MTS) group at Vale Canada Limited’s Garson Mine assessed seismic hazard with the objective of assigning practical mitigating controls to zones identified as having a high rockburst potential. Initially, seismic hazard was computed using the Seismic Excavation Hazard Mapping (SEHM) software developed by the Mining Innovation Rehabilitation and Applied Research Corporation (MIRARCO) at Laurentian University, Canada. More recently, Vale Sudbury Operations partnered with the Australian Centre for Geomechanics and the University of Western Australia’s mXrap consortium. Through the consortium partnership, MTS at Garson Mine implemented the mXrap seismic data analyses platform, including the grid-based seismic hazard assessment tool. Building on 10 years of seismic hazard assessment experience at Vale Garson Mine, this paper summarizes a comprehensive case study, comparing the two tools (SHEM and mXrap) used at Garson Mine to assess, quantify, and represent seismic hazard. Subsequently, results of the Garson Mine comparative seismic hazard study will be discussed, emphasizing the need for an all-inclusive hazard assessment tool, focused on delivering practical mitigating controls that further enhance the overall safety of seismically active underground mines.

Apr 26, 2022

By J. E. deMasi

Over the past 12 years, Exxon Coal U.S.A., Inc. has shipped over 150 million tons of coal from two mines, Rawhide and Caballo, located in the Gillette, Wyoming, area. These mines are operated by The Carter Mining Company, a division of Exxon Coal. Shipments have moved to more than 25 electric utility plants in the west, midwest, southwest, and south. The customer plants have represented a wide variety of configurations, sizes. design criteria, emission standards, and operations in different parts of the country. We have learned a great deal about the performance of Gillette area coals in utility power plants during this period. This paper covers some of the highlights of Exxon's experience with these coals in customer plants. I will focus specifically on things mining engineers may be able to do to make the product better for the customer's use.

Jan 1, 1989

By T. Acton

The Zarafshan/Newmont Joint Venture is currently operating in the Republic of Uzbekistan producing in excess of 400,000 oz. of gold per year from low grade oxide ore stockpiles adjacent to the Muruntau open pit gold mine located in the Kyzylkum desert of central Uzbekistan. Four stage crushing and screening produces a final product for heap leaching, Merrill-Crowe processing, and local refining for International market export. The Zarafshan/Newmont Joint Venture is the first major commercial project of its kind in the former Soviet Union to be successfully negotiated, engineered & constructed, and placed into continuous operation,

Jan 1, 1997

By Yadong Xue, Fei Wang, Hongwei Huang, Yan Sun

"Increasing attention to subway tunnel maintenance is being paid with the high speed development of urban rail transit system in China. A novel moving tunnel inspection equipment based on machine vision is developed in this paper. High resolution image acquisition system is proposed for tunnel crack and leakage inspection. The main components of this image acquisition system includes high speed CCD cameras, linear lights and high performance computer. To inspect the crack less than 0.3mm with a 3-5km/h speed in subway tunnel, we need to consider resolution and line rate of camera, pixels of cameras, range of inspection and illumination intensity of lights simultaneously. The optimization design is proposed to make the equipment more convenient for tunnel use. Entire tunnel situation can be detected and recorded in a single inspection process. This equipment has already been verified in Shanghai subway tunnel for defects inspection.1. INTRODUCTION In China, the quantity of subway tunnel has reached a large scale in recent years. Until 2014, there had been more than 2300km of subway tunnel in China which accounted for nearly three quarters of Chinese urban railway system (Zhang Chen,2015). In some metropolises like Beijing and Shanghai, most of the metro tunnels has already run over 20 years which within maintenance phase. This has brought about plenty of inspection work and maintenance work to guarantee the tunnel under the serviceability limit states. The increase of running mileage of subway tunnels in China has been displayed in Fig 1."

Jan 1, 2016

By Paul L. Boni

Trona, Na3(CO3)(HCO3) ? 2H20, is mined in quantity from saline facies of the Eocene Green River Formation of southwestern Wyoming. The Green River deposits are the world's largest known resource of natural sodium carbonates. An estimated 127 billion tons of trona ore are known to occur in beds exceeding 4 ft in thickness (Wiig and others, 1995). Twenty-five trona beds, exceeding 3 ft in thickness, and covering at least 100 mil have been identified. The beds are numbered sequentially in ascending stratigraphic order. Trona beds underlie more than 850 mil (bed 17) and are up to 37 ft thick (bed 1) (Culbertson, 1966). Five underground mines, operating in beds 17, 19, 20, 24, and 25, process trona to produce soda ash (sodium carbonate). A total of 11,837,703 short tons of soda ash were produced from 17.1 million tons of trona ore in 1997 (Kostick and Clark, 1998). A detailed study of trona bed 17, using techniques of petrography and X-ray diffraction, has been undertaken in the Solvay trona mine, near Green River, Wyoming. A continuous, vertical-channel sample was taken from near the production shaft for this study. At this location, bed 17 is 12.6 ft thick and includes several stratigraphic markers that are easily correlated throughout the mine and in surrounding drill cores. Bed 17 in this area averages 90% trona through its entire thickness (Wiig and others, 1995) and 95-100% trona in the lower two-thirds of the bed. Mineral impurities include water-insoluble dolomite, quartz, pyrite, clays, and other minerals and partially water-soluble northupite and shortite. Northupite, Na3Mg(CO3)2C1, contributes to chloride contamination in the soda-ash product and is concentrated in the upper one-third of bed 17, which is left behind as roof rock. Northupite has two modes of occurrence: (1) as bedded strata with dolomite, chert, clay, and shortite and (2) between primary trona crystals in trona spar. Petrographic and mineralogic data indicate that this section of bed 17 was deposited subaqueously during its early and late history and may have undergone periods of deposition in a subaerial or marshy environment. Stratigraphic data indicate that trona accumulated at an annual rate of 2-4 in. per year. During trona deposition, dolomite, CaMg(C03)2, precipitated in parting layers when new water entered the lake, freshening supplies of calcium and magnesium. The lack of clay minerals in the trona facies suggests water input may be by means of springs, as opposed to overland flow. Clay occurrences in thicker dolomitic partings within the trona facies indicate periods of episodic overland flow, possibly resulting from storms in the surrounding basin.

Jan 1, 1999

By Hai Lin, Renshu Yang, Yongliang Li, Shizheng Fang

With the aim of solving the large deformation problem of surrounding rock in coal mine roadways with a thin sand-mudstone interbed roof, transportation roadway 1603 in Haoyuan Mine was considered. The failure mechanism of surrounding rock was studied through comprehensive on-site investigations, borehole image analysis, mineral composition analysis, and other means. Numerical simulations were performed to determine the influence of roof layer thickness, lateral pressure coefficient, and coal rib strength on the stability of the interbedded roof. The main reasons for support failure and deformation of the roadway are softening and swelling of the sand-mudstone interbed roof upon exposure to water, insufficient support capacity of the roof due to the soft coal rib, an unreasonable support scheme, or poor construction quality, which can reduce the bearing capacity of surrounding rock. Based on our analysis, a control strategy was devised for a thin coal-mudstone interbed roof. The support scheme combines long and short cable support, strengthening of the coal rib to consolidate the roof, and partially shotcrete grout, and was found to improve the overall mechanical strength of surrounding rock and maintain the stability of the thin sand-mudstone interbed roof. The results of the numerical simulations and monitoring data indicated that the proposed support scheme effectively controls the deformation of the surrounding rock of thin sand-mudstone interbed roof of coal mine roadways while maintaining the safety and stability of the surrounding rock and supporting structure.

Dec 12, 2022

By Angela K. Braden

Igneous rock exposures occupy only a minor portion of surface area (<18 mi2) in Arkansas, and are divided into two major groups: nepheline syenite (7 mi2) and syenite complexes (8 mi2), with various dikes and sills representing the remaining surface exposures. The syenite complexes have been the sites of major vanadium and minor titanium production during the past 50 years. Nepheline syenite exposures were important in the early production of locally used building stone; however, aggregate and roofing granules have now become the principal market for the production of nepheline syenite in Arkansas. Nepheline syenite intruded into a sequence of Paleozoic sedimentary rocks in Arkansas and is exposed in two areas: in Saline County near the town of Bauxite, and in Pulaski County at Granite Mountain, just southeast of Little Rock. Although the central Arkansas region had been investigated thoroughly for bauxite by the early 1950s, the nepheline syenite resources of the region have yet to be evaluated systematically by the state. Arkansas nepheline syenite was evaluated for its ceramic uses in 1952. Some recent industry interest has revolved around its potential use as a sand-blast abrasive. The largest exposed areas of nepheline syenite, located at Granite Mountain, currently are being mined by the Minnesota Mining & Manufacturing Company (3M) and McGeorge Contracting (Granite Mountain Quarry). 3M has been in operation since 1947 and mainly produces roofing granules. A fine powder produced by 3M during crushing that is marketed under the name Donnafill? recently has seen use as filler in self-compacting confined construction and as an additive (frit) in common brick. Since the early 1960s, Granite Mountain Quarries has produced a variety of aggregates, ranging from riprap to industrial sand, and recently constructed a computerized hot-mix-asphalt production facility. Approximately 4.5 million tons and 1.2 million tons of syenite were produced from Granite Mountain and 3M, respectively, during 1979. No production values are available after this date; however, combined production from both quarries is estimated to be at least 6 million tons annually.

Jan 1, 1999