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By H. Walqui, A. Buendía

The Toquepala concentrator expansion project incremented the capacity of the existing concentrator by 15,000 Metric tons per day (t/d), from 45,000 to 60,000 t/d. The plant is located in southern Peru,1,200 km southeast of Lima. The implementation plan for the expansion project was based upon an engineering and procurement contract, and a construction contract. The overall Project Management was by Southern Peru Copper Corporation (SPCC). The expansion followed a very aggressive schedule that considered a construction period of only ten months, with minimum interference to the existing facilities. Major equipment was purchased during basic engineering. This paper details the design, construction, and commissioning of the 6.4 m diameter by 10.2 m long ball mill, and the performance of the milling circuit during the first two months of operation.

Jan 1, 2003

By Michael Jatczak, Brett Robinson

The South Bay Ocean Outfall tunnel is located at the U.S./Mexico Border and is one link in a system designed to treat and dispose of raw sewage entering the Tijuana River Valley from Mexico. The 11 finished diameter tunnel extends 19,000’west from the bottom of a 200 deep, 36 diameter drop shaft. At the western terminus of the tunnel, a Riser shaft connects the tunnel to conveyance and diffuser pipes on the seabed. The tunnel runs through the San Diego Formation, consisting of clay, silt, sand, gravels, cobbles, and boulders. A Mitsubishi Earth Pressure Balance (EPB) Tunnel Boring Machine equipped with a large variety of monitoring and control devices was used. This paper will provide an overview of the Project’s construction, with special emphasis on the value of the electronic data acquisition system.

Jan 1, 1999

By R. R. Klimpel

The efficiencies of plant scale comminution processes are often evaluated by various indices that are calculated and/or measured somewhat independent of the performance of any associated downstream froth flotation processes. In order to compare some specific comminution factors such as energy utilization, media consumption, equipment utilization time, etc. comparisons of comminution efficiency independent of flotation behavior are appropriate. However, as more and more detailed plant level information is gathered on the joint and highly interactive nature of comminution and froth flotation, it is becoming increasingly obvious that knowing and using simple efficiency indices are not enough. What is needed are more performance related measures of the efficiencies of the combined size reduction -froth flotation system for effective plant level economic optimization to occur. The purpose of this paper is to present some examples of important interactions that influence the joint efficiencies of size reduction and froth flotation processes.

Jan 1, 1998

By W. M. Schafer

The risk that water quality will be degraded by mining activity can be evaluated using risk analysis techniques. Water quality impacts can occur where water-rock interactions with tailings, waste rock, or leached ore lead to increased loading of constituents into surface or groundwater. Constituent loads contributed by mining facilities are determined by the migration route and chemical evolution of mine water. Mass load contributions from mines can be determined by estimating the prototype pore water in contact with mining waste, predicting the rate and timing of flow, assessing the degree of geochemical attenuation, and modeling chemical mixing with natural surface or groundwater. Mining facility siting and design measures can alter the chemical evolution of mine water by varying the quantity or quality of flow. Stochastic risk management techniques provide a powerful tool for quantitatively identifying the environmental consequences of various siting and design alternatives.

Jan 1, 1998

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal mining operations can cause various disturbances to surface structures ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of the travelers and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (e.g., decks, beams, abutments, etc.) are presented. A number of mitigation measures to protect the bridge structures are recommended along with an actual application case.

By Mauricio Brücher, Juan Camus

This article deals with open pit mine planning and a computer technology known as Direct Block Scheduling, or “DBS”. This is an emerging technology for modeling mine exploitation strategies using mixed-integer linear programming. This technique has proved to yield stronger economic results compared to the Lerchs-Grossmann (“LG”) algorithm currently used at the beginning of the mine planning process. The article briefly describes the shortcomings of current practice; then, this delves into the superior results obtained by DBS technology compared to current practice. Finally, the article argues that results achieve so far by DBS could be enhanced even further. To do this, the framework to apply this emerging technology, which is also used in current practice, should be modified to better exploit the capabilities of DBS technology. To better understand this change, an illustrated case study is presented at the end of the article.

Jun 25, 2023

By Arthur W. Ruff

Estimated reserves of high-grade iron ore at Serra dos Carajás total 16 billion metric tons and have an average grade of 66.7 percent iron, 2.2 percent combined silica and alumina, and 0.05 percent phosphorous on a dry basis. Hematite is predominant and no significant sulfur or other deleterious elements are present. Figure 1 illustrates the comparative magnitude of the Carajás reserves. Serra dos Carajás is located in northern Brazil, about 550 kilometers southwest of Belém, Pará. It is six degrees south of the equator between the Xingu and Tocantins Rivers. Both rivers flow northward toward the Amazon River. The greater part of the area is covered by thick jungle, and the most practical means of access is by air. Figures 2 and 3 show the location of Serra dos Carajás. Figure 4 shows the distribution of the major iron-ore deposits.

Jan 1, 1973

By Nick A. Hasenack

A full survey of the laboratory and blast-furnace tests on 2 types of acid pellets is given. From the laboratory tests, carried out in an atmosphere containing hydrogen, it appears that type B, produced out of 100% magnetitic ores, has a far better low temperature disintegration index and a lower reducibility index than type A, produced from a hematite/magnetite mixture. The swelling index, chemical composition and mechanical properties of both types of pellets do not differ significantly. From the blast-furnace test, carried out with a burden consisting of 45% of pellets and 45% of sinter with basicsty ratio about 2.2, and at constant driving rate, it follows that there is no significant relationship between the disintegration value of the pellets and the blast-furnace permeability. If also is concluded that the lower reducibility of the type B pellets leads to a significantly higher coke consumption.

Jan 1, 1975

By Rod L. Norfleet

Cemented tungsten carbides are a sintered powder - metallurgical product essential to modern industry. Because of their moderate unit price and our dependence upon foreign sources for the component raw materials, a growing recycling industry has developed in the United States. There are two basic approaches taken to recycling cemented carbides; those which leave constituting materials unaltered or direct-reuse and those which separate the constitutes back to the raw components. To separate the carbides back to their raw components usually requires expensive chemical processing and is thus confined to the lower value materials such as grinding sludges. The direct-reuse methods recycle cemented carbides back to an intermediate level, a powder capable of being recompacted and resintered into a functional end-product. The three most commonly used methods of direct-reuse recycling, the coldstream process, bloaching and the Bernard or zinc process, are reviewed,

Jan 1, 1984

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence induced by underground coal mining activities, especially longwall mining operations, can cause various problems to interstate highways ranging from structural integrity to drivability to safety. Accurate subsidence prediction, correct influence assessments and effective mitigation measures are the keys to ensuring the safety of highway traffic. The surface subsidence prediction program, called comprehensive and integrated subsidence prediction model (CISPM), was developed based on the principle of influence function method and has been validated with a large number of subsidence measurements. In this paper, the techniques to use the predicted final surface movements and deformations for assessing their influence on the integrity and functionality of highway structures — such as road surface pavements, concrete slabs and transverse joints — vehicle dynamics, comfort level and drivability are presented. A number of mitigation measures to protect the highway structures and to ensure traffic safety are proposed, along with an application case.

By Frank C. Schora

The Institute of Gas Technology for many years has dedicated a large portion of its research effort to the development of a practical solid-fuel-based gasification process to produce a synthetic natural gas equivalent. The work is being done to prepare for the day when supplemental gas will be needed. This program, initially supported by the American Gas Association, and now by both the Department of Interior's Office of Coal Research and the American Gas Association, has developed the IGT Hydrogasification Process. This process, now entering the pilot plant stage, is based on the high-temperature, high- pressure hydrogenation of coal with a hydrogen-steam bearing gas. Product gas from this step is cleaned and catalytically methanated to produce a high-Btu gas. Estimated production costs indicate the process will be competitive with natural gas in certain areas of the country when required.

Jan 1, 1969

By L. Adler

The valuable Maximum Utilization Factor (MUF) concept has been extended to other rotating excavators beyond stripping shovels and draglines. In this concept the boom reach and bucket capacity are multiplied to get an MUF, then normalized by dividing by the equipment weight. Statistical analyses were applied to the remaining shovels (hydraulic and cable), draglines, and backhoes. Positive correlations were found. Stripping shovels and draglines were also re-examined. The results provide an estimate of equipment diggability and encourage versatility by the interchange of the boom and the bucket. The concept further clarifies the existing equipment classification by delineating general excavating, loading, and stripping kinds. The results also forecast trends, and noted innovative advances and possible retrogression. Extension to other boom excavators, such as front-end loaders is recommended. The MUF concept provides one of the few indices of gross external characteristics available to the engineer-user of equipment.

Jan 1, 1990

By A. G. Provost

On April 3, 1981, Harrison Western Corporation was awarded a contract by Amax Alloy - A Division of Amax Inc., to sink the Henderson #5 ventilation shaft. The project was located on the Henderson Mine site 88 kilometers west of Denver near the town of Empire, Colorado (Figure I). The Henderson No. 5 Shaft, located in an Alpine environment at an elevation of 3145 meters, was a 9.8 meter diameter concrete lined shaft with a total depth of 793 meters. Work started and continued with Harrison Western employees until January 15, 1982. At that time, Amax made the decision to continue the shaft-sinking with their own labor, and with Harrison Western providing supervision under a management service contract. Shaft sinking continued under this arrangement to October 1, 1982, at which time Amax put the Henderson No. 5 project on standby status until further notice.

Jan 1, 1986

By Yi Luo, Jian Yang, Hua Jiang

Surface subsidence events induced by underground longwall coal-mining operations can cause various disturbances to surface structures, ranging from integrity and stability to functionality problems. Highway bridges, as a kind of special road construction that can only tolerate smaller movements and deformations than road pavements, are particularly susceptible to severe influence caused by subsidence-induced ground movements and deformations. However, based on accurate subsidence prediction and correct influence assessments, efficient and effective mitigation and remediation measures can be designed and implemented to ensure the continuous service of bridges, safety of travelers, and smooth mining operations. In this paper, based on the predicted final and dynamic surface movements and deformations, the techniques to assess subsidence influence on the integrity, stability and functionality of bridge structures (such as decks, beams and abutments) are presented. A number of mitigation measures to protect bridge structures are recommended, along with an actual application case.

By Per-Martin Sandgren

LKAB's ores have specific mineralogical properties that make them especially suitable for the production of super-grade concentrates. Conditions are particularly good for this purpose at Malmberget, where a concentrate for high-purity sponge iron production has been produced for many years. Until 1978 the approximate assay was 71.2 % Fe and 0.45 % SiO2. Since then the assays have been improved by process modifications to approximately 71.5 % Fe and 0.20 % SiO2. Scope exists for still further improvement. In recent years the production of fractioned concentrates has been started. The material lies within the size range 74-125 µm and the approximate chemical analysis is 71.6 % Fe and 0.30 % SiO2. Other special products are under discussion. The Malmberget ores are also suitable for the production of high-purity direct reduction pellets with a SiO2 content below 1 %.

Jan 1, 1981

By R. R. Young

Good afternoon gentlemen. It is always a pleasure to talk about a subject dear to our hearts--the high speed transfer of bull; materials. Specifically, today we will be reviewing the engineering approach to an age old problem of ship loading and unloading. You may be puzzled by the title of this paper and we will attempt to explain this for you--particularly the use of the words "New Era", since high speed automated facilities are nothing new to the material handling engineer. The new era in material handling designs refers to an all out concerted effort to provide custom engineering tailored to specific operations and economic requirements of the client. It shuns hardware type of engineering wherein existing machines and devices are dusted off and reapplied. It provides automation when automation can be justified and it exemplifies the application of systems engineering to solve specific problems.

Jan 1, 1967

By C. O. Brawner, A. Bellamy, D. S. Cavers

Pit slope designs at Nickel Plate Mine have used relatively steep interim and final wall slopes of 60 degrees overall. The rock is unusually strong and tough with most discontinuity sets being steeply dipping. An integrated program of monitoring and drainage has been used. Stopes of large extent which are generally unsupported occur on the property. For the most part, no deterioration of the stability of the stopes has occurred over the last 30 or more years. Mining methods through these areas have used a combination of fill s placed via VCR drop raises and crater blasting of the backs. One of the major challenges in mining through the stope areas is to maintain slope stability conditions and to reduce dilution of the higher value ore zones occurring immediately around the stope areas. The paper discusses geology, slope stability and mining methods at Nickel Plate Mine.

Jan 1, 1988

This chapter contains the edited transcript of the "Gold Heap Leach Information Exchange" session that was held at the 1990 SME/AIME Annual Meeting in Salt Lake City, Utah. The exchange occurred on the afternoon of February 27, 1990. The session was intended to act as a forum for discussing some of the more prominent operating problems associated with heap leaching precious metals. The information exchange was very successful. The exchange consisted of several panelists introducing and discussing different topics, follow by a comment and question period. This transcript contains the panelists' presentations as well as comments and questions from the floor and the panel. Extraneous comments and remarks have been edited out. Some wording has been changed for clarity, but the transcript is basically an accurate account of what was said. At the end of the transcript are two papers submitted as part of the panel discussion

Jan 1, 1990

By R. N. Torbin

Foster-Miller has recently developed a new concept.for a highly specialized shaft lining system. This innovative shaft lining system uses a continuous slipforming placement technique. lining the shaft from the bottom up such as in a raised bored shaft. Although this part is not unique, the concept is designed to use polyurethane foam instead of concrete for the liner material. Furthermore, the concept is designed to attain rates of advance of 30 m/hr. The polyurethane foam liner is designed to be thinner (100 mm) than a conventional concrete liner (300 mm). It will eliminate the high cost associated with the erection and operation of an on-site concrete batch plant. The system will be designed to be operated remotely, requiring few personnel for its operation. This system (or parts of it) may be appropriate where fast construction speed is required or where a jointless liner is needed.

Jan 1, 1988

By Donald P. Richards, David W. Campo, Michel Coudry

This paper presents a review of the grouting works of Line 2 of the Greater Cairo MetroSystem. The Nile River alluvial deposits underlying this ancient city provided for a challenging and sometimes difficult grouting project. Permeation grouting using state-of-the-art computerized grouting techniques, as well as extensive ground treatment by jet grout, was per-formed for soil consolidation and/or groundwater control. During the project, over 425,000m3 of ground was treated, requiring 1.4 million linear meters of drilling and PVC injection pipe, 54,000 m3 of bentonite cement and 230,000 m3 of chemical and mineral grout. In addition, over 70,000 m3 of ground was treated using the jet grout method. Relative to major international transportation projects, the grouting works for Line 2 of the Cairo Metro represent one of the largest worldwide grouting endeavors to date.

Jan 1, 1997