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By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

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 Frank Matter

The production of ultrafine slurries and powders is possible with small media made out of Si02, A1203, Fe203, Zr03 or other raw materials due to the fact that since approximately 12 years from now, entirely new machines have been developed which allow to use this small media for the production of ultrafine pigments. Basically we distinguish between two grinding methods which are: A.) Dry Grinding with Air Classification: This method is used for more than fifty years but only since four years this technology is realized with small grinding media. Many problems like cooling, abrasion, control of the media flow, separation media from product, grinding media recycling etc. had to be resolved before it was possible to get in full production with this new system. Hereafter a flow-sheet of such a TRZK mill with an air classifier especially designed to produce end products with a top size between 2,5 and 3,0 micron and with an average particle size between 0,3 and 0,5 micron.

Jan 1, 1983

By George M. Meisel

This paper is devoted to a discussion of the factors governing design of concentrators for large grinding circuits. Emphasis is placed on the manner in which use of ever larger grinding mills has affected the size of grinding bays, service cranes, gear reducers and electric motors, and the selection of ancillary equipment for cushioning of the starting load of large mills. Information is presented on the effect of using large grinding mills on the capital and operating costs of concentrators, e. g. : (Fig. 1) ? Benefits in lower cost of mills, drives and materials handling equipment, plant space, power, grinding media, operating labor and maintenance, and in ease of instrumentation and automation. ? Penalties in distribution of materials from the grinding mills to multiple lines of equipment which have not been developed to commensurately large sizes, and higher cost of ancillary equipment.

Jan 1, 1968

By S. A. McGhee

ASARCO Incorporated embarked on a modernization and expansion program to improve overall operating efficiencies and to more effectively develop the large mineral reserve at the Ray Complex Open-Pit Mining operation located near Kearny, Arizona. Major elements of this Ray Modernization and Concentrator Expansion Project included engineering and construction of a 54,400 MTPD (60,000 STPD) In-Pit Crusher and Overland Conveying System. and a 24,200 MTPD (30,000 STPD) Copper SAG Concentrator and Tailings Disposal System. Detailed engineering, procurement, and construction management were initiated in November 1989 under contract with Bechtel Corporation. Field construction commenced in May 1990 leading to mechanical completion and start-up during February 1992.

Jan 1, 1993

By T. C. Vogt

Earlier we described the uranium mineralogy of an areally broad sampling of Crownpoint ore, including the characterization of organic carbonaceous material associated with the uranium mineral. (1) We also reported on the leaching behavior of Crownpoint ores with a mild alkaline leaching system, oxygen (02)-sodium bicarbonate (NaHC03). (2) There was a wide range of leaching responses, with samples from some areas leaching at a slow rate with low uranium recovery. Evidence indicates that in these samples the organic material is intimately associated with the uranium mineral and shields it to some extent from contact by the leachate. (1,2) One method to obtain faster leach rates and higher recoveries is to use a chemically severe leaching system such as sodium hypochlorite (NaOCI) as an oxidant. (3) The use of sulfuric acid (H2SO4) and an oxidant for leaching ore in surface milling operations is widely practiced to effect high recovery of uranium (U308) from the ore. (4,5,6) The U308 is mobilized as the disulfate complex, U02(S04)224-, or possibly, the trisulfate complex, U02(S04)34-, is the soluble species. (7) Sulfuric acid leachate formulations were used in the first in-situ leaching operation in the Shirley Basin in Wyoming. (8) More recently H2S04 formulations have been used in the Rocky Mountain Energy field tests in the Powder River Basin (Bear Creek) and in the Teapot forma¬tion at Nine Mile Lake site near Casper. (9,10) Laboratory studies related to the use of H2SO4 for in-situ leaching have been reported (11-17) and Yan has .reported packed column leach studies on Crownpoint ore using H2504 and oxidant. (18)

Jan 1, 1981

By William M. Kester

Finely sized Upper Freeport coals are beneficiated to reduce ash and sulfur using high-intensity magnetic separation to process both (1) raw, untreated coal as well as (2) raw coal which was pre-treated thermally with steam and air. Substantial, sulfur and ash reduction can be obtained using both approaches to magnetic beneficiation of coal fines, but evidence indicates that pre-treatment which would constitute a costly supplementary step is technically inferior to the direct beneficiation of raw, untreated coal. These bench-scale studies demonstrate that if high-intensity,; high capacity, dry, magnetic beneficiation equipment can be developed and' installed at coal burning power plants or at appropriate points in coal preparation plants substantial quantities of sulfur may be removable from coal after pulverization as a means' to reduce air pollution.

Jan 1, 1965

By Eleanor Sonley

In October 2000, temporary seismographic stations were installed above the Trail Mountain Mine, Emery County, Utah, USA to supplement a regional network. Over seven months, 1826 mining-induced seismic events were recorded with a magnitude range of M 0 to M 2.2 (Arabasz et al., 2002, 2005). Routine event locations for this dataset cluster around the longwall mining activity during the recording interval. However, applying a double difference relocation technique to the routine locations significantly improves the correlation between mining activity and event location. The resulting relocations depend greatly on station distribution and the number of arrival time picks. We use this dense temporary array to assess station distribution requirements for applying the double difference technique at other mines by systematically removing data from available stations, thus simulating sparser networks. The insight gained using the Trail Mountain dataset is used to develop a metric for assessing the usefulness of above-mine networks and to develop a tool for expanding seismic network coverage. To verify the appropriateness of these tools for wider application, we examine data from two additional mines located in the western United States. Improving the relative locations of mining-induced seismic events highlights the association of these events with active portions of the mine. Clusters, regions of quiescence and relative timing of events can be used by mine operators to assess hazard, optimize production, and evaluate performance of mine plans. The lessons learned from this study may be used in future network design to improve accuracy of event locations at other mines.

Jan 1, 2009

By Robert Moore Lewis

A unit for separating minerals into two prescribed size fractions, designated as a Lewis Hydrosizer, was developed at the North Carolina State University Minerals Research Laboratory. Ore samples with different mineral compositions, including coal, were separated effectively with the laboratory continuous unit. Commercial size units are in operation in North Carolina and Mexico, and under construction in Norway. Additional units are being build or are in the planning stage at several companies.

Jan 1, 1983

By A. Ramage

Since late 2010, CH2M HILL has been working with a confidential client who holds a long-term commitment to sustainable development (SD). The commitment is aligned with all three elements of the triple bottom line: people and society, ecosystems and environment, and financial and economic systems. These commitments are carried forward by the firm?s executives, managers, and operational sites, and are evident in materials posted on the company?s public website. These materials include a formal sustainability report prepared in accordance with the Global Reporting Initiative (GRI) guidelines (GRI, 2006), a report that outlines key SD challenges and progress toward the GRI targets, and a delineation of risks and opportunities outlined in the firm?s Form 10-K and Annual Report. In keeping with its commitments to SD targets, our client wished to consider SD issues in its decision processes for facility expansion or new projects. The company engaged CH2M HILL to meet this goal, based on working relationships established through existing contracts and CH2M HILL?s leading capabilities in sustainable solutions.

Jan 1, 2012

By V. E. May

Has your organization adopted Six Sigma as part of their Performance Improvement strategy? What about Lean manufacturing or Lean Six Sigma? If you already have any of these business process improvements in place where will you go next? In this article we will focus on transforming your organization beyond Lean Six Sigma to the next level of performance. In the future companies can take another quantum step forward by combining Lean Six Sigma with advanced Root Cause Analysis (RCA). The value of taking this natural progression on the way to achieving new levels of organizational excellence is presented.

Jan 1, 2011

By V. E. Housman

EPA's Mining Waste Section within the Office of Solid Waste is continuing to collect and analyze information on mining waste management practices. Starting in 1991, the Mining Waste Section has continued to conduct site visits and prepare case study reports on the waste generation and management practices of operating mines. In choosing sites to study, a reasonable attempt was made to provide diversity in mining commodity types, geographic regions, geology, climate, and environment. To date, EPA has visited the following mines: Asarco Troy (copper) in Montana, Newmont Rain in Nevada (gold), Cyprus Thompson Creek (molybdenum) in Idaho, LTV Steel (iron) in Minnesota, Phelps Dodge Morenci (copper) in Arizona, Doe Run Fletcher (lead) in Missouri, Brewer (gold) in South Carolina, IMC Four Corners (phosphate) .in Florida, Pennzoil Culberson (sulfur) in Texas, Nerco Cripple Creek (gold) in Colorado, Copper Range White Pine (copper) in Michigan, Magma San Manuel (copper) in Arizona, Colosseum (gold) in California, and several gold placer mines in Alaska, including the Valdez Creek Mine. EPA has prepared a case study report on each facility. The mine operators were provided an opportunity to comment on their respective site visit report and their comments have been included in' each respective report. These site visit reports have in turn been incorporated into technical resource documents which provide a detailed description of each mining sector. EPA is currently reviewing the technical resource documents and plans to release the documents in the Spring of 1994.

Jan 1, 1994

By B. C. Litzinger

Minerações Brasileiras Reunidas S.A. - MBR is a brazilian iron ore mining company geared for the export market. It is controlled by Companhia Auxiliar de Empresas de Minerações - CAEMI through its subsidiary Empreendimentos Brasi leiros de Minerações - EBM which holds 51% in MBR and is formed by CAEMI, the six major japanese steelmills and five japanese trading companies, Universe Tankships, Inc., and Indústria e Comércio de Minérios S.A. - ICOMI. The remaining 49% of MBR's capital are held by St. John del Rey Mining Company, a subsidiary of The Hanna Mining Company. MBR iron ore reserves exceed 1.5 billion tons of high grade ore distributed in 36 deposits located in the so-called IRON QUADRANGLE in the State of Minas Gerais. The Aguas Claras Mine is the largest presently known and highest grade deposit owned by MBR. Other mines such as Pico, Mutuca and Jangada are in operation at a combined rate of production of about 2 to 2. 5 million tons per year. The project consists of mine, railroad and marine terminal (slide). The Aguas Claras deposit, which is located about six kilometers southeast of Belo Horizonte the Capital of Minas Gerais, was selected for initial development. The Sistema Regional Centro of the Rede Ferroviária Federal, through its 6th Division known as the "Central " is responsible for the transportation of MBR ore, and provided the necessary railway construction to connect Mine and Terminal. The Terminal is located on Guaiba Island near the entrance to Sepetiba Bay, at about 120 kilometers west of Rio de Janeiro.

Jan 1, 1974

By P. G. Semple

For the last four years, the Kilborn Group of Companies has been involved in several major projects in the Confederation of Independent States (CIS). These include the Kumtor project, the Kubaka gold project, the Kazgold project, the Aginskoe project and the Jerooy project. These projects are all in various stages of detailed engineering and construction. Western mining companies are pursuing mining opportunities throughout the world in search of ore bodies for development. The quest for profitable mining ventures has led mining companies to South America and Asia and, more recently, to the former Soviet Union. When considering the CIS, several factors should be considered. The most notable are geography, mining culture and previous mining production.

Jan 1, 1996

By Perry N. Halstead

The primary objective of the structural geology portion of the Kennecott Copper Corporation-U. S. Bureau of Mines Pit Slope Stability Study was to determine the attitude, geometry, and spatial distribution of geologic structures of the west wall of the Kimbley Pit for use in designing a maximum stable slope for the pit. A corollary objective was to develop and refine techniques for collecting and analyzing geologic structural data with emphasis on numerical methods that could be integrated with other aspects of pit design. Surface mapping techniques used were a modification of conventional joint set mapping and a detailed linear sampling method. For subsurface investigations both oriented core and a borehole camera were used. It was determined that the major faults in the area were favorably oriented for mining a steep stable slope. The jointing or natural fracturing, although complex, was not random in attitude and consisted of several persistent fracture sets and a number of secondary sets. The attitude of the persistent fracture sets was favorable for steeper slope angles, and these attitudes were used in the design considerations. There was no significant difference between the attitude of the fracture sets determined from the former and new slope face.

Jan 1, 1968

By E. Woodburn, H. W. Smith, M. C. Fuerstenau, R. Putman

This paper presents a review of developments to date in computer control practice, based in large part on Canadian experience. The basic problem examined is that of stabilizing control; matters considered are control strategies, hardware and software aspects of system implementation, reliability, human factors, and economic results.

Jan 1, 1976

By Thomas A. Morley

This paper deals with the minimization of ventilation costs for the controlled-flow mine ventilation network. Cost elements considered include the cost of power and the fixed cost of the fans. The problem is modeled in a mixed-integer programming format and solved via the branch and bound method. Computational experience with sample problems is discussed.

Jan 1, 1983

By Wayne A. McCurdy

I welcome the opportunity to meet with you and discuss the work and program of the Office of Coal Research. Our programs are oriented to serve the conservation objectives of the Johnson Administration and of the Nation by seeking out the most efficient and best uses for coal. We believe that even if only a portion of our program is successful, the coal industry and the Nation will benefit far out of proportion to our expenditures. Operating with a budget of $7,220,000 in Fiscal Year 1966, OCR sponsors contract research which offers potential for achieving benefits to the coal industry in the form of new production and new markets. This directs us into many areas of research activity: in coal combustion, in advancements in mining methods and coal preparation, in new uses for coal, and in associated economic and marketing research.

Jan 1, 1966

By Serkan Saydam, Ercument Yalcin

This paper presents the results of Caldagi Nickel-Cobalt Ore Deposit's, located in Turkey, reserve and ultimate pit limit design analysis. Reserve analysis of any deposit requires two steps. First one is to constitute of block model of the deposit and second step is to generate ultimate pit limit. The block model of the Caldagi ore deposit has been created by means of geostatistics. The reserves of nickel and cobalt in this block model are defined as resource, approximately 12 million tons of nickel and 1 million tons of cobalt with average grades of 0.9% Ni and 0.03% Co, respectively. Ultimate pit limit analysis has been performed by considering economic, technical and legal factors. In this paper, the ultimate pit limits are generated by Lerchs & Grossmann (L&G) algorithm. As a consequence of ultimate pit limit design, total amount of tonnage to be excavated is 1.4 billions of tons, 700 million of which contains ore and 747 million of which is the tonnage of waste.

Jan 1, 2002

By W. S. Urbanski, A. L. Devernoe, M. S. Walker

Theory and practice are described for a new processing method capable of precise mineral separations based primarily on differences in particle specific gravities at specific gravity split points from 1.5 to 21.0 and beyond. Separations are analogous to those achieved using rotating heavy media, except that the effective specific gravity of the fluid is created magnetically using a relatively dilute, low-viscosity, water-based magnetic fluid. Results reported here for a large, laboratory flow-through separator include: 1) 99% grade with 97% recovery in single pass separation of a suite of heavy minerals from quartz at I0 kg/h, 14 tph/rm2 of duct cross section, 2) 90% grade and recovery in single-pass separation of mixtures of sand-size, non-magnetic rutile (4.23 specific gravity) and zircon (4.72 specific gravity) at throughputs of 35 kg/h, 47 tph/rm2 of duct cross section, 3) partition curves having Ep90-10 transition widths 5% or less of mineral specific gravities, and 4) essential confirmation of the theory.

Jan 1, 1991