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By Margaret Armstrong

The increasing cost of developing new mines and the need to mine more marginal deposits have led mining companies to use more sophisticated estimation methods such as kriging. But until recently, coal mining companies have shown little or no interest in these techniques. However, the stringent quality controls which are now placed on coal have led to a surge in interest in improved estimation methods. This can be seen from the -, number of research projects by private companies and governmental agencies on the application of geostatistics to coal reserve estimation. At present, most of these programs are centered on the problem of estimating the tonnage and the average grade (i.e. ash percent, sulphur content, calorific value, etc.) of the coal in-situ. See, for example, Sabourin (1975), Woods (1976, 1979), Pauncz and Nixon (1979) and Armstrong (1980). These studies show that the established techniques of linear geostatistics can be applied successfully to coal deposits. The study by Woods is particularly interesting because he had access to the actual production figures as well as the initial sample data from the no 2 seam in the Greenside Colliery owned by the Anglo-American Corporation. He showed that the estimates obtained by kriging were consistently closer to the actual production figures than those given by three other estimation methods. This confirms the superiority of kriging as a method of estimating block values for coal. Another advantage of geostatistics is that it can be used to determine the optimal spacing between drill holes. An example of this is given by Armstrong for the coking coal deposit in the Bowen Basin, Australia.

Jan 1, 1981

By M. L. Rizzone

Since time immemorial, Mother Nature has been transporting slurries with both air and water serving as the carrier medium. Consider for example the formation of the continental shelves off our coast lines which are being formed by rivers emptying erroded land surface and depositing it into bays and gulfs. As the erosion processes take place, the fines are suspended in water which flows in streams and rivers and deposits where the velocity of the flow reduces sufficiently to allow the fines to settle out. The same process in some crude form is provided when one hoses his driveway or patio and moves dirt so as to provide a cleaning action. These examples illustrate rather crudely how the formation of slurries allows for the transport of solids. In recent years, this mechanism has become fairly well understood and slurry pipelining of many materials is now a vivid reality. The movement of liquids in pipelines necessarily occasions the use of pumps for the purpose. Those of us who have had some rub with the petroleum industry are familiar with the transport of solids through mud pumps and cementing and fracturing pumps where the movement of slurries is an everyday matter. In the drilling of an oil well the circulating fluid utilized to remove chips which are cut by a drill bit from holes drilled deep in the earth is called drilling mud. This substance contrary to what the name might imply is usually a fairly sophisticated material designed to develop certain characteristics which are desirable in the drilling process. The particles which have been cut by the drill bit are suspended in the moving column of fluid and brought to the surface and deposited. The separation of the cuttings from the drilling fluids is accomplished by the use of shaker screens and settling pits. However, it is impractical to remove the fines completely from the drilling fluid and as a result they are pumped through the mud pumps back into the circulatory stream.

Jan 1, 1969

By R. L. Guerguerian

Hydrostatic trunnion bearings were recently provided on large Semi-Autogenous Grinding (SAG) mills driven by wraparound motors assembled on the head to shell flanges. A conventional SAG mill would have a ring gear driven through one or two pinions. The effects of the magnetic air gap forces from this new SAG mill drive arrangement on the performance of the bearing are discussed. A step-by-step systematic analytical de-sign of the hydrostatic trunnion bearing is presented, followed by a discussion of grinding mill erection requirements to conform with the design. A brief comparison with other bearing types and their response to the effects of magnetic air gap forces are also presented.

Jan 1, 1992

By B. C. Scott

Every year more and more mining companies are entering joint ventures to look for minerals. Large companies join large companies, small companies join small companies, and large companies join small companies. Mining companies join oil companies, chemical companies, machinery companies, and companies with no other connection to the minerals business. And well they might, for here is a way for both minerals-oriented companies and those that have no background or knowledge of the minerals business to get actively involved in an outwardly-attractive but high-risk enterprise with the chance to participate in a lucrative minerals find. Thus, for reasons beyond those normally associated with joint ventures in many other fields, corporations, companies, groups, and even individuals are looking to joint exploration ventures as the answer to all problems of getting into or staying in mining.

Jan 1, 1972

By Werner Burger

After its first introduction in 2013, Variable Density TBMs have increased their application significantly in mechanized closed mode tunneling. Throughout a variety of successfully completed and ongoing projects since then, Variable Density TBM technology has demonstrated its advantages in a wide range of applications. This paper will present the developments and lessons learned from these projects as well as the future potential of Variable Density TBMs.

Jun 13, 2021

By Neil B. Prenn

Mine Development Associates, Inc. was formed in March of 1987 to provide mine engineering assistance to the mineral industry. To be competitive with other firms, Mine Development must be able to provide quick and accurate ore reserves and mine plans for clients. Commercially available mining software was necessary for Mine Development to assist the client. This paper describes how Mine Development chose mining software, the time involved in getting up to speed, and several case histories of how the software is used. The case histories discussed include: * 3,000,000 ton gold deposit in Nevada. * 5,000,000 ton gold deposit in South Dakota. * 1,000,000 ton gold deposit in Australia. * +100,000,000 ton gold deposit in Nevada. * 25,000,000 ton carbonate deposit in California.

Jan 1, 1989

By Terry M. Tilley, Gregory P. Sherry

Purpose This is a unique project because the mining and tunneling industries have become highly mechanized and cannot normally accommodate a project where surface disturbance must be minimized or eliminated when there is less than 10 feet of ground cover. More traditional less mechanized methods must be employed and the skills and techniques for accomplishing the work have become all but non-existent. Therefore, this article highlights those areas of specialized skills and techniques. Methods The article will describe the design approach, the method(s) of ground support selected, the method(s) of excavation selected, the planning, scheduling and materials selection process. In addition, the article will describe the actual production characteristics and the results of the project. This approach will concentrate on productivities, adaptations to actual conditions and the quality of the end product. The design approach basically was to insure that the temporary support methods were adequate for the excavation and shoring stage of the project. The final concrete liner was designed using conventional structural design methods with the goal of constructing a tunnel that will last 100 years. The methods of support were spiling and variations of spiling in order to provide advance temporary ground support. In this project spiling is steel channel cantilevered and driven into the ground ahead of the working tunnel face which supports the ground allowing the face muck to be removed with overhead protection’. Conclusion This will be a discussion of the applicability of the methods. The actual performance of the excavation and shoring methods will also be evaluated. The final concrete liner completion results, the actual production rates and the conformance with budget and schedule will be addressed.

Jan 1, 2005

By Steven A. Savage

Agrico Chemical Company, as we presently know it, is the result of the coming together of several different fertilizer operations. The Williams Companies, our parent organization, first entered the fertilizer business in 1971, when it acquired the fertilizer operations of the Gulf Oil Company. This gave us, among other things, the manufacturing facility at Donaldsonville, Louisiana. In 1972, The Williams Companies acquired Agrico Chemical Company from Continental Oil Company, bringing in a manufacturing facility and phosphate mines at Pierce Florida. Our Florida Mines are in the region commonly known as the Bone Valley Region of Florida. The majority of the phosphate fertilizer produced in the United States utilizes rock mined in this region. The Donaldsonville Plant was originally built in 1967-68 on the site of the old Faustina Plantation at an approximate cost of $80,000,000. (This plant is commonly referred to as our Faustina Plant.) Until such time as Agrico was acquired from Continental Oil, the Donaldsonville Facility was solely used to upgrade phosphoric acid into finished granular products.

Jan 1, 1986

By P. Tsang

To gain insight into the current status of pillar design practice in the underground coal mines of United States, a survey has been undertaken in the late 1993 and early 1994. A total of 552 room-and-pillar mines and 75 longwall mines have been surveyed to collect general, geological and mine plan information. The collected information are critically analyzed with special emphasis on the pillar design criteria adopted in these mines. A safety factor analysis has also been carried out for the pillars in room-and -pillar mines.

Jan 1, 1995

By Arash Nikvar-Hassani, Lianyang Zhang

To address the drawbacks of the conventional portland cement/fly ash (PC/FA)–based cementitious material currently used in practice to construct pumpable roof supports (PRSs), a novel cementitious material has been developed based on geopolymerization technology. The novel cementitious material is comprised of two pumpable grout streams: Stream 1 is a slurry composed of pozzolanic material and high-calcium additive and stream 2 is an alkaline solution comprised of a gelling agent. Biopolymer has been added to the second stream to provide ductility to the geopolymer cementitious material. In the laboratory scale, systematic experiments have been carried out to investigate the viscosity, setting time, and uniaxial compressive strength (UCS) of the new cementitious material and develop the right recipe for field applications. By collaborating with industry and the National Institute for Occupational Safety and Health (NIOSH), full-scale PRSs have been constructed and tested. The results show that (1) the novel cementitious material based PRSs has much higher peak UCS and similar or higher residual strength than the conventional PC/FA-based PRSs; and (2) unlike the PC/FAbased cementitious material, the novel cementitious material shows good long-term durability with nocracking/disintegration when exposed to air.

Jul 1, 2023

By Eduardo Rojas, Pedro Landeros

El Teniente Mine expansion plans are currently under development and construction stages through an integrated project strategy that will allow the continuity of future mining. The deepest sector corresponds to Andes Norte Project that faced rockburst risks during tunneling in a completely different manner, implementing different actions for the mitigation of seismic hazard and seismic risk management, based on the following main aspects: rock mass preconditioning techniques such as destress blasting and hydraulic fracturing, improvement of rock support design with the inclusion of elements with higher energy dissipation capacities, use of mechanized equipment for the most critical activities in addition to re-entry protocols and improvements in geological, geomechanical and seismic data collection procedures to reduce the uncertainty of rock mass behavior. The current seismic risk management strategy integrates all of these elements and is the basis of construction methodologies in use, supporting the technical feasibility of tunneling in high-stress environments.

Apr 26, 2022

By P. C. Holloway

La Oroya zinc ferrite (19.5% Zn, 26.6% Fe, 0.052% Ga, 0.075% In) was roasted with coal under conditions more oxidizing than normally used in a Waelz kiln, and the roasted residues were leached with 200 g/L H2SO4. Overall zinc recoveries of up to 97% were achieved, with 35% of the zinc reporting to the fume after roasting at 1,100°C with a bituminous coal addition of 20%. Under these conditions, 93.2% of the Cd, 13.4% of the Cu, 33% of the Ga, 61% of the In and 18.2% of the Pb were recovered either in the fume or in the leach solution. At 2006 metal prices, the value of the recovered metals is comparable to that obtained from commercial Waelz kiln processing of this residue. Zinc in the franklinite (ZnFe2O4) mineral is reduced to zinc vapor, and, after oxidation, some of the zinc is found as ZnO or as Zn2SiO4 in the roasted residue. Iron reacts to form either hematite (Fe2O3) or magnetite (Fe3O4), with no metallic iron detected in the roasted residue, and less than 2% of the iron is solubilized during leaching. The residue produced after roasting and leaching is, therefore, much more stable than the residue from Waelz kiln processing and should be suitable for disposal in a landfill.

Jan 1, 2008

By Donald J. Olson

The North 27th St. ISS Extension tunnel will, under present plans, be the last constructed section of Milwaukee Metropolitan Sewerage District?s (MMSD?s) existing deep tunnel system. The 6.5 m (21 ft) finished diameter tunnel is approximately 3,260 m (10,590 ft) long and is located in NE Milwaukee County. When disputes over the pro-cesses to be used in owner-directed pre-excavation grouting in rock threatened the completion date stipulated between MMSD and the State of Wisconsin, the MMSD and J.F. Shea, the contractor, entered into a unique agreement. Shea accepted responsibility for all shaft and tunnel grouting and water control during the project in exchange for settlement of claims related to grout quantities and perceived delays. This significantly reduced risk for the MMSD and helped ensure the stipulated completion of the project.

By L. Bloom

In 1996, lack of confidence in assaying methods and sample handling affected companies as diverse as Bre-X and Timbuktu. Both share prices and the ability to raise financing are impacted when the quality of assay data is suspect. Overseas projects are subject to enhanced scrutiny when local facilities are used that are unfamiliar to brokers, financing agencies and banks. Quality control systems can be -implemented but there are associated costs. These costs should reflect the risk to the mining company, investors and financiers and the size of the proposed investment. In this regard, assay control call is considered a form of insurance to enhance the value of an exploration or mining project.

Jan 1, 1997

By T. Shumka, M. J. Druckenmiller

"INTRODUCTION As we push further into the 21st century and closer to a more efficient mine, safety and operational enhancements are the two major keys towards attaining success. The Crusher Vision Automation System (CVAS) is a technological advance that will allow an operator to achieve higher safety and higher operational goals in the same piece of equipment. The CVAS is a patent pending system and method for measuring and maintaining the closed side setting (CSS) on gyratory crushers. In the same equipment and technology package, the CVAS will also allow safer placement of main shaft pieces for maintenance and replacement. This technology yields multiple uses and allows a site to significantly enhance safety and operational efficiencies. This measurement technique is used to provide more accurate data and faster data collection times than current techniques used today. It will give crusher operators accurate and reliable measurement for the CSS in a live, operating environment. Measurement data can be collected in five minutes allowing for fast adjustment of the mantle position and subsequent enhancement and streamlining of a crusher and downstream flowsheet. The advantage of this system is that it is permanently mounted at the crusher location, where the operator can turn the system on and off as many times as they like throughout the day with a goal of maintaining a constant CSS gap based on production and maintenance criteria to help streamline operations and enhance safety efficiencies.Regarding its other main functional area, mainshaft maintenance, it allows this work to be performed remotely while keeping personnel safer and out of harm’s way. SAFETY ENHANCEMENT The safety factor enhancement with this system is extreme. It does not require the use of overhead cranes, cleaning out the crusher, lowering people into the crusher or having the operator lower paint cans or lead balls into the crusher pocket while the crusher is in operation for measuring the setting. In order to perform the CSS measurements, the operator only needs to operate the laser through manipulation of a joystick while watching the video feed. Danger of a person falling into the crusher while trying to take measures is eliminated, as are the effects of handling lead balls and tracer dyes."

Jan 1, 2015

By David J. Hatem

Public-private partnerships (PPP) are gaining in popularity at the federal, state and local levels as the public sector seeks private capital to finance infrastructure and other projects that traditionally have been funded with public funds. In general, a PPP involves a development agreement between a public owner and a private sector concessionaire. Under the development agreement, the concessionaire is responsible for financing, designing, constructing and typically operating and maintaining the completed project for a concession period (often multi-decades in duration). The concessionaire typically enters into an agreement ? the design-build agreement ? with a design-builder to design and construct the project. The concessionaire may secure financing from banks, investors or from a combination of these and other sources (collectively the financier). While the PPP experience in the United States has been modest to date, an increasing number of projects involving tunneling or other significant subsurface work are already being delivered in the PPP mode. Public owners have significant options to address risk allocation for subsurface conditions on PPP projects. The same sound and fundamental principles of fairness in risk allocation that apply in other major subsurface projects should be applied and adopted in the PPP context

Mar 1, 2014

By Monserrat Rebolledo, John L. Uhrie, Candice Simms

Jetti Resources has developed a catalyst which overcomes the passivation of primary sulfides, enhancing the heap leach recovery of copper from chalcopyrite. It is important to emphasize that heap leaching of copper sulfides, whether with or without the Jetti catalyst, is a biooxidative process. We have demonstrated the efficacy of Jetti’s technology in bioreactors, with a chalcopyrite-dominant porphyry ore. In the presence of Jetti’s technology, optimal bioleaching conditions significantly increase copper extraction by 2.6 times that of the baseline.

Feb 1, 2025

By H. L. Holden

The single line grinding circuit at Bond Gold's Colosseum mine consists of variable speed drive semi-autogenous (SAG) milling and secondary grinding with a fixed speed ball mill. There are several advantages and disadvantages of operating SAG mills with variable speed drives. Discussion in this paper will focus on the effects of variable speed SAG milling in relation to mill liner wear, grinding media consumption, and mill operating availability. Operating experiences, corresponding mill data, and pertinent design changes are also presented.

Jan 1, 1991

By T. W. Meikle

Three nutrient amendments and a biological seed inoculant were evaluated for use in establishing vegetative cover on waste rock substrates. Randomized blocks were placed on three substrates. Treatments included two types of organic fertilizer, mineral fertilizer, Azospirillum bacterial inoculant, plus controls. The seed mix consisted of native grass species adapted to low nutrient conditions. Canopy cover has been monitored for three growing seasons. Results indicate: 1) two of three substrates support plant growth following amendment with organic fertilizers; 2) organic fertilizers increase cover substantially over mineral fertilizer; and 3) Azospirillum had no effect on canopy cover.

Jan 1, 1999

By Frank M. Howell

Creede, one of the younger major mining camps in Colorado, grew spectacularly to a town of eight or ten thousand people in the early 1890's following discovery of rich ore in the Amethyst and Last Chance mines. Gross metal production in gold, silver, lead, copper and zinc rose to a maximum of four million dollars a year in 1893. Annual production dropped to much lower figures and ranged between one hundred and five hundred thousand dollars per year during the period from 1914 to 1940. Production reached a gross of eight hundred thousand to one million dollars per year by the mid-1950's. In the years 1953 to 1957, Steven and Ratté conducted geologic investigations which were carried on as part of a cooperative program of the U. S. Geological Survey and the Colorado Metal Mining Fund Board. In a preliminary report on the Creede District, Steven and Ratté suggested that the Bulldog Mountain Fault Zone appeared to be a favorable structure to prospect. On the basis of that recommendation, augmented by independent work done by Manning W. Cox, the property was acquired, transferred to Bulldog Mountain, Inc. and financed by an O. M. E. loan. Late in 1963 Homestake Mining Company, under a Lease and Option Agreement, backed the venture by furnishing additional funds plus management.

Jan 1, 1969