Search Documents

By J. C. Nigro

The potential use of prereduced pellets in the burden of the blast furnace continues to be a topic of interest. Several excellent papers have been written describing the theoretical and experimental rewards. (1) (2) (3) (4) (5) (6) (7) (8) (9) Significant increases in iron output and substantial savings in coke consumption are major advantages over conventional iron oxide pellets. The savings are especially important in areas where good coking coal is at a premium. Lower handling and transportation costs may also be factors favoring prereduction. When considering the overall cost of making and smelting prereduced materials the optimum metallization level becomes significant. An analysis by Agarwal and Pratt of the thermodynamic aspects of blast furnace operation with all prereduced pellets shows that the criteria controlling coke consumption depends upon the degree of reduction and upon the percentage of oxygen (present as FeO) removed by solution loss.(8) The authors state that although the chances of obtaining large fuel savings are greatly improved when metallization is high, reduction to the highest degree, which is costly, may not result in the lowest energy requirement per ton of hot metal; thus, over reduction could possibly result in wasted energy in the blast furnace.

Jan 1, 1968

By Martin Herrenknecht

Tunnel boring machines continue to develop to take on not only larger and larger diameters but also more difficult ground conditions. Ground conditions consisting of unstable faces with water pressures up to 15 bar has required innovative design approaches. A systems approach has been required to produce tunnelling machines that can not only safely excavate the tunnel but do so in an efficient, cost effective manner that stresses production and labor saving approaches. This paper will review the current design developments and present recent projects where these most recent principles have been applied.

Jan 1, 2008

By Richard E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on developing the tools needed to mechanize a mining operation with a reasonable expectation of success. Mechanical mining entered the 1990s with new machines, new operating methods and new ideas for the future. Mechanical mining can provide higher production, increase safety, reduce roof support requirements, create smoother openings for better ventilation, substitute continuous production for cyclical drill-and-blast procedures, and create opportunities for automatic and teleoperated control. The full promise of this important technology still lies ahead. Obstacles include: • Long-term production prediction: Mechanical systems have a high capital cost. Although recouped by lower operating costs, the tradeoffs are not always clear to mine operators. • Cutting tools for hard rock: Rock of more than 103.4 MPa (15,000 psi) cannot be cut by flexible mining machines. • Machine designs: Many machines cannot convert the required power into rock cutting capability. • Engineering: Better use of the machines in the mine is needed.

Jan 1, 1994

By B. W. Stunkard

Hibbing Taconite Company is located by the cities of Hibbing and chisholm near the center of the Mesabi Range, approximately 169 km (105 miles) from the Canadian Border. The plant site is equidistant from these two communities, about 6.4 km (4 miles) from each. A 169 km (105 mile) railroad connects us with the port of Superior, Wisconsin, where the pellet production is loaded into lake carriers for lower lakes destinations. Immediately to the south of the mine area is the world famous Hull- Rust-Mahoning Mine which produced more than 700 000 000 million tons of red ore between the years 1893 and 1973.

Jan 1, 1979

By L. Clark

Despite near-record commodity prices, the mining industry continues to search for ways to maintain profits in these times of steadily increasing energy prices and steadily decreasing grades. The pressure is still on today’s miners to continuously improve their operations because they know that one day prices too will drop. Some, however, have seized the opportunity to employ systematic methods to reduce costs and increase the efficiency of their workforce and equipment. As a result, closer attention is being paid to scheduling and the value that could be added by defining the extraction sequence that maximizes the net present value [NPV] of a project. This paper will discuss the challenges faced by Newmont Mining Corporation [Newmont] at its operations and the application of sophisticated software tools and methods in its search of solutions to this problem.

Jan 1, 2007

By G. E. d’Aquin

Sources of sulfur have varied based on technology and societal needs. It has been mined in its elemental form for centuries. Twentieth century technology brought thermal mining (Frasch, 1894) to the forefront of sulfur extraction. Then, by the 1980s, petroleum processing generated almost 40 percent of the 50 Mt (55million st) of sulfur in all forms (SAF) produced in the world. Metals processing (the reclamation of effluent gas by various means as “sulfur in other forms,” or SOF) followed at 30 percent of all sulfur values produced and then Frasch at 22 percent. Petroleum and gas processing now generate most of the elemental sulfur produced in the world. Single Two Frasch mines remain, one each in Iraq and Poland. Conventional mining of small to insignificant volumes also survives in Russia, Latin America and Indonesia. The volume of “recovered” sulfur (the name commonly given by the industry to hydrocarbon-derived material) generated will increase faster than energy consumption as oil and gas with greater amounts of sulfur are used and environmental restrictions on the sulfur content of the fuel consumed become more stringent.

Jan 1, 2005

In 1988, at the request of members of the Society for Mining, Metallurgy, and Exploration (SME) Inc., the president of SME formed Working Party No. 79, Ore Reserve Definition. Its mission was to develop guidelines for the public reporting of exploration information, resources and reserves. These guidelines were published in the April 1991 issue of Mining Engineering (pp. 379-384), and as a document entitled “A Guide for Reporting Exploration Information, Resources, and Reserves” in January 1992. Work continued on an ad-hoc basis until 1996. Working Party No. 79 was then renamed the SME Committee on Resources and Reserves and became a standing committee.

Jan 1, 1999

By Alejandro Gutiérrez, David Ahues, Paola Merino, Felipe González

A Discrete Elements Method (DEM) study of load movement within a SAG mill 12,192 × 7620 (40′ × 25′) in normal operating conditions is performed. The purpose is to determine how the geometry of the lifters affects the kinetics of the load inside the mill. Specifically, the changes produced by the incorporation of inclined lifters and spiral or helicoidal pulp lifters to the kinetics are evaluated. Four study cases are identified: first, the base case corresponds to a conventional geometry; the second case corresponds to inclined lifters incorporation; third case corresponds to a mill with helicoidal discharge; and the fourth case corresponds to a mill with inclined lifters and helicoidal pulp lifters. To save computational resources, the water that enters the mill has been modeled by varying the coefficient of restitution. The results of a series of experiments are presented to determine how this coefficient varies when having impacts on surfaces with different liquid levels. A comparative analysis is made of the following variables: mean transport speed and material flow, for normal operating conditions. Taking as reference the mill with straight lifters and radial pulp lifters (case 1), the case with the inclined lifters and radial pulp lifters increases the material discharge flow less to 76 mm of size by 5.1%, and this value increases even more when the helicoidal pulp lifters are incorporated reaching a 58.6%. The most significant change is seen in the flow through the grates and the pulp lifters discharge, which can increase substantially improving the operation.

By T. Clarkin

This paper presents a hydrologic closure design concept to minimize the risk of water discharges from closed mine tailings facilities. It evaluates the applicability of U.S. Nuclear Regulatory Commission guidelines to develop acceptable designs for the closure of tailings facilities that have a calculated adequate surcharge capacity for environmental protection and an emergency spillway for dam safety. The guidelines provide a basis to estimate an acceptable surcharge capacity of a Probable Maximum Flood series for storage of surface runoff. To be conservative and for redundancy with respect to dam safety, an emergency spillway is provided to pass the Probable Maximum Flood. Depending on the annual water balance, the surcharge capacity may be used by surface runoff and minor amounts of sediment that accumulates in the impoundment from year to year. The emergency spillway crest is then set at this level or above the surcharge capacity, whichever is higher. An example is given of the active Red Dog Mine tailings facility in Alaska where this method was used for the preliminary design of the tailings main dam at its ultimate closure configuration.

Jan 1, 2012

By Randy Reed, Barbara J. Arnold

Respirable crystalline silica poses a significant health risk, with the American Lung Association estimating that 2.3 million workers are exposed to silica in the workplace. This includes mine workers as well as those in many other industries. Reducing dust formation is sometimes not possible so other methods to reduce exposure are critical. These methods include the use of surfactants to reduce airborne dust particles. However, it is the proper selection and application of surfactants that leads to reduced dust exposure. A discussion of how surfactants work, especially for silica dust, leads to guidance for surfactant selection followed by a review of technologies for their application.

Feb 1, 2024

By John Hanna

Recently. researchers at The University of Alabama have developed a two-step method for the treatment of phosphorus sludge that includes bulk removal of phosphorus by physical separation techniques followed by remediation of the residual P4 in the sludge using a novel wet air oxidation technique known as "HSAD", Tests made on samples of the electric furnace phosphorus sludge have demonstrated that essentially complete and fast removal of the P4 in the sludge can be achieved by the HSAD wet oxidation treatment, Further studies were made to determine the applicability of the two-step process on sludges of various origins. P4 contents different pre-treatment and storage conditions, The present work discusses the mechanisms and factors controlling the HSAD wet air oxidation remediation approach.

Jan 1, 1992

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

By C. Chamberlain

The mining industry continues to underpin the regional economy. Australia, benefiting from a weak currency, receives 27% of the total goods export value from non-energy mining lead by aluminium, iron ore, gold and nickel. Consolidation has eliminated CRA, Comalco, North, Savage, Acacia, Ashton, Great Central, Aberfoyle, Placer Pacific, Plutonic, Normandy and RGC leaving Rio Tinto, BHP-Billiton, WMC, MIM and, increasingly, the South African companies Anglo, Gold Fields and Harmony as dominant players. Exploration stagnates with expenditure dropping 40% in Australia and 80% in PNG from peak levels. Major new regional developments include Rio’s West Angles iron ore project, Newcrest’s Ridgeway gold-copper mine and Inco’s Goro nickel-cobalt project in New Caledonia.

Jan 1, 2002

By K. Zabrusky

Estimation of high grade epithermal vein deposits can present challenges in correctly representing the continuity of grade within an undulating structure. One solution to this problem is to use dynamic anisotropy to follow local variations in the strike and dip of veins. Dynamic anisotropy (D.A.) allows the search parameters to change block by block throughout the model to account for the local variations. Presented here is a study of a vein that changes orientation down-dip. A traditional resource estimate using one search ellipse orientation was performed. The resulting estimated grades did not accurately reflect those of the sample data. Using a search ellipse with an average value for the two distinct dips caused the grade estimation to be less representative than desired. Rather than performing domain-based analysis with different search ellipses, the issue was corrected by using Datamine Studio 3?s D.A. function. The 3D vein trend was used to estimate the dip and dip direction of the vein in each block. The resulting D.A.-estimated model follows the two dip trends of the vein. This software makes a previously tedious task faster, and allows for more accurate estimations.

Feb 27, 2013

By Osvaldo A. Bascur

Intelligent systems (IS) technologies have received much attention in a wide range of process engineering applications including process operations. With the revolutionary progress in information and computer technologies applying the latest technologies in metallurgical complexes has become a serious challenge to both management and technical teams. Objects and components are changing the way everyone relates to their computer and networks. Goals of real time performance monitoring includes maximizing the profitability by maximizing production, improving efficiency, attending product quality, costs, maintenance, environmental and safety regulations. Designers must consider the greatly expanded desktop computing, Microsoft object technology, Internet and how to build these systems. This paper discusses some opportunities and challenges using objects, components in designing applications and integrating intelligent systems tools. Two examples using performance equations and IS technologies applied to mineral processing are presented.

Jan 1, 1997

By Basilio Giurgola, Jeremiah M. Jezerski, Filippo Azzara, Federico Bonaiuti, Russell H. Lutch

The Northeast Boundary Tunnel Project consists of a 23 ft diameter, 27,000 ft long, CSO tunnel, multiple underground connections, and significant surface works within an urban corridor. The NEBT alignment depths range from 60 to 140 ft and includes seven shafts ranging in depth from 77 to 155 ft with diameters varying from about 19.5 to 56 ft, some as in-line connections and others required adits for connection to the main tunnel. This paper focuses on the design and construction of two major underground connections which are the First Street Connector Tunnel and the Mount Olivet Road Diversion Sewer.

Jun 13, 2023

By John H. Bassarear

The never ending search for lower unit costs led Pima Mining Company's management to study various alternatives shortly after Expansion III was completed. It soon became apparent that a considerable amount of ore assaying 0.35% copper had to be moved in order to maintain mill feed at the desired 0.54% copper content, which is the overall grade of the ore reserves. Detailed investigations revealed that for a period of 8 - 10 years, about 14,000 tons per day of 0.30 - 0.40% copper ore would pass by the crusher en-route to the low grade stockpile. This ore is very hard, very clean and has to be mined at a relatively uniform rate. A six month pilot plant run testing autogenous and semi-autogenous grinding gave very encouraging results. Since no mining costs need to be charged to the extra tonnage (it had to be mined anyway) the only major costs would be against milling. The decision to proceed was made in August 1970 and Fluor-Utah was retained as the prime design construction contractor. Ore was first put through the new mill on December 29, 1971. By March of 1972 design tonnage of 14,000 TPD had been attained. The first three expansions at Pima Mining Company, 20 miles south of Tucson, increased mill capacity from 3,000 TPD to 36,000 TPD. These expansions included a separate, conventional, three stage crushing plant plus additions to the existing concentrator that primarily duplicated the then current flowsheet. Expansion IV, however, consisted of an entirely new and separate primary crusher and a completely new mill building located about 2,000 feet southeast of the 01 d concentrator. The new mill, using semi-autogenous grinding, produces scavenger and rougher flotation concentrates that are pumped to the old mill for regrinding, cleaning, thickening and filtration.

Jan 1, 1973

By K. Oraee

Mining Ventures are considered as high risk projects and therefore managing the risks is inevitable. Risk assessment is an important part of the complex process of risk management, hence applying appropriated and practical methods for ranking the risks associated with projects, can help to perform a better risk management. In this research the applicability of using Techniques for Order Preference by Similarity to Ideal Solution (TOPSIS) method for risk ranking in an underground mine, extracting by block caving method, was studied. Via this method, the risk associated with reserve estimation ranked as the first while in conventional method (P-I Matrix method) located in the sixteenth. Also there were significant differences in ranks of the other risks. Considering the more criteria, with different weights, in comparison with conventional methods, the results comprised from TOPSIS method are more reliable. By implementing this method risks are ranked better and more realistic and consequently then will be managed more efficient.

Jan 1, 2011

By D. C. Fuller

CoaLiquid, Inc. (CLI) has been in the coal- oil-mixture (COM) business for over five (5) years. The initial pilot processing facility was replaced by a 2000 barrel per day commercial production facility in August of 1979. For over two (2) years CLI has been expanding its efforts and conducting large scale production and combustion demonstrations successfully in many locations across the United States. To facilitate the marketing effort, CLI has recently constructed a special trailer containing all equipment needed for a temporary COM retrofit. CoaLiquid has conducted commercial scale combustion demonstrations in the following types of combustion units: kilns, calciners, industrial boilers, blast furnaces and driers.

Jan 1, 1982

By P. A. Mingione

AEROPHINE® 3418A is a unique sulfide mineral promoter produced by Cyanamid, based on phosphine (PH3) chemistry. It has proven effective as a collector for the sulfide minerals of copper and particularly lead (galena), as well as for secondary gold and silver values. AEROPHINE 3418A has widest application as a Cu and/or Pb collector for complex ores of Cu-Zn and Pb-Zn, which frequently have significant quantities of associated precious metal values. Advantages shown in the use of AEROPHINE 3418A are improved selectivities against Zn-and Fe-sulfides, increased precious metals recoveries, reduced total collector consumptions for Cu and/or Pb flotation, and increased flotation kinetics leading to higher recoveries of these values. Operating plant, pilot plant and laboratory test data from treat-ing different ores are presented, demonstrating the advantages in use and preferred application of AEROPHINE 3418A.

Jan 1, 1991