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By C. I. Everson

The Elkhorn mining district is located 35 kilometers southeast of Helena, Montana, on the southeast edge of the Boulder Batholith. Geologically the district consists of a folded sequence of Paleozoic limestones and shales which have been thermally metamorphosed and altered by monzonite to diorite intrusives related to the Cretaceous Boulder Batholith. For the most part, the skarns are associated with metasomatic: replacement of calc-silicate hornfels, diorite and marble by iron rich, dark green pyroxene, garnet, sulfides, the district contains excess of 30,000 Kg.

Jan 1, 1992

By Jianliang Li, Xi Peng, Guorong Lu

This paper describes a wind tunnel modelling study on airflow and pollutant concentration in a large open pit mine located in southern China. A 1:1000 scale model of the surface mine was fabricated and placed in a wind tunnel. Airflow velocity in the test section of the wind tunnel can be continuously adjusted from 0.3 m/s to 6.0 m/s. In this study, both the present pit condition and the projected final pit condition were modelled. Airflow direction and velocity profiles were obtained. The impact of wind direction and velocity on airflow was also studied. The pollutant concentration distribution in the open pit was simulated using smoke, and a distribution profile was obtained. Respirable dust concentrations at the mine site were measured, then its concentrations at the projected final pit condition were estimated using the obtained pollutant concentration distribution profile. Under normal meteorological conditions, it is expected that the respirable dust concentration for the final pit should not exceed the government standard. Key Words: wind tunnel modelling, open pit, surface mining, scale model, mine ventilation, airflow profile, point source.

Jan 1, 1993

By W. R. VanSlyke

Scrubbing is gaining increasing recognition as a valuable tool in the treatment of Mesabi Range intermediate iron ores. In general, the earliest washing plants included log-washers in their various flowsheets. While log-washers certainly did impart a degree of scrubbing to the crude ore, such treatment bears little resemblance to the type of scrubbing being practiced today. At the time that these early plants were erected, only the true wash-ores were being processd. ("Wash-ores" are defined as crude ores in which relatively coarse chunks of almost completely liberated iron are found in a matrix of loosely-consolidated fine sand.) To treat ores of this type, sizing at approximately 65 to 100 mesh was sufficient to produce a merchantable concentrate. As crudes were being treated in which there was little "locking" of iron and silica, log-washers tended to disappear and large screens and classifiers took their place in Mesabi range flowsheets. The "screening and classification" type of flowsheet 'had its greatest usage in the 1945-55 period, generally speaking. During this same period, many operators found it necessary to supplement the "wash-ore" type flowsheet with heavy-media treatment.

Jan 1, 1959

By F. Romero, L. Yacher, M. Orchard

Specific software tools for Statistical Multivariate Analysis combined with real time process data were applied to Concentrator Plant at Compañía Minera Doña Inés de Collahuasi SCM in Chile, basically to two Mill Lines, each one with one SAG mill (32’x15’8MW)and one Ball mill (22’x36’9.7MW). The main objective was to empower the operator actions using process patterns references instead of process variable set-points. Pattern clustering and the analysis of pattern deviations regarding normal or desired pattern, allows for improvements in process control and the further implementation of soft sensors for those variables not included in the initial model.

Jan 1, 2003

By V. Svalbonas

When the Trelleborg Divisions of Boliden Allis and MPSI merged, a unique opportunity occurred for two independent mill fabricators to compare various design procedures and the research upon which they were based. This paper documents such a comparison in the structural design area. Several SAG mill analyses are compared using both Boliden Allis and MPSI methods. The differences and similarities are then utilized in a correlation of critical stress definitions and the acceptable design and inspection criteria.

Jan 1, 1992

By Y. J. Zhang

This paper presents the results of a recent study on the development of an in-situ testing method for determining the coal strength in mine pillars. The strength testing is performed in the horizontal holes drilled into the coal rib using the penetrometer. It is a hydraulically powered device that uses an indenter to press the surface of the borehole until the load reaches the failure point of coal. The pressure and the penetration of the loading pin are recorded by the data acquisition unit. The results collected from several coal mines indicate that this testing method is ideally suited for the realistic coal strength measurements. The new testing system not only improves the accuracy of pillar strength determination, but it is more cost efficient than the conventional method.

Jan 1, 1995

By R. H. T. Garnett

Reserve estimation is a process that commences with sampling and culminates in the issuance of a reserve statement. The tin, gold and diamonds that occur as marine placers on the continental shelf are low grade with very erratic mineral distributions. Sampling, using a variety of special equipment, determines the extent and grade of the mineralization. The sample size is important, especially for diamonds. Together with the sampling density, it determines the accuracy of the grade estimate. Bulk sampling is a confirmatory process. The choice of mining equipment, either new or developed from onshore activities, dictates the unit costs, the cutoff grades and the selectivity of extraction. Thus, the size of the blocks that comprise the mining plan and the reserves are determined. A variety of estimation methods of different reliability are available, with the most sophisticated being kriging. Dilution and losses during mining must be taken into account in estimation, and a grade-volume curve should be constructed. Diamond deposit estimation also involves an extra variable, the dollar value of the stones. During and after mining, essential feedback on the accuracy of un estimation may be given by the RIE factor and by a mineral balance. Reserve estimates are required for several reasons and may be subject to public disclosure. The use of the correct definitions is, therefore, important.

Jan 1, 1999

By Judson H. Whitman

To evaluate intelligently and to market a source of rare earth raw material, it is necessary that the producer understand the requirements of the processor and the manner in which these requirements effect the value and salability of his product. This paper will be an attempt to aid in such an understanding. The majority of rare earth processors are primarily chemical companies, not mining or metallurgical companies, as the complexities of the processing procedures are' much more chemical in nature than metallurgical. The rare earths and the rare earth industry are normally divided into two groups - the ?light? or cerium group and the ?heavy? or yttrium group. They are so named because cerium and yttrium are the most common elements in 'heir respective groups and are so divided on the basis of mineralogical and chemical characteristics. The dividing line of the two groups is not rigidly fixed but usually is considered as being between samarium (atomic number 62) and europium (atomic number 63). Although the two groups are quite similar, processing procedures differ significantly, hence most processors tend to specialize in one group or the other. There is, however, a growing tendency toward participation in both groups.

Jan 1, 1960

By Yukika Miyashita, Takahiro Inoue, Kenji Namikawa, Masashi Matsumoto, Junichi Koseki, Yoshihiro Terashima

"In order to construct an underground two-layer expressway branch junction structure with a height of 14.7 m and a width of 22.3 m, two shield tunnels in each layer were combined by using a non-cut-and-cover enlargement method in sedimentary soft rock. Before and during the construction work, preliminary analysis, in-situ investigations and laboratory tests were conducted to ensure the construction safety and to evaluate the deformation characteristics of sedimentary soft rock. The construction project was safely executed without any water leakage or collapse of tunnel working face. The predicted results from preliminary analysis were almost similar to the measured values. From the detailed investigation of measured results, it was confirmed that the deformation characteristic of the sedimentary soft rock was observed to a small extent as the ground deformation derived from construction work. INTRODUCTION In recent years, some newly constructed urban expressways in Japan are being planned as underground structures due to the consideration of roadside environment. The construction of such underground expressways is frequently conducted using a shield tunneling, a typical one of non-cut-and-cover methods, to prevent any adverse effect to traffic in arterial roads, operation of nearby commercial establishments, and daily lives of local residents during construction work. For underground urban expressway, the connections with existing road network on ground surface or on elevated sections are indispensable, which require the construction of an underground branch junction with large cross-section. This raises a technical difficulty regardless of the open-cut or non-open-cut construction method."

Jan 1, 2016

By Joseph B. Alberts, David D. DiPonio, Francis B. Manning

From 1996 to 2001, Wayne County and 13 suburban Detroit communities constructed the Downriver Regional Storage and Transport System (DRSTS) to improve area water quality, protect public health and alleviate basement flooding. The project consisted of a 10-mile long storage and transport tunnel, a pump station at the existing wastewater treatment plant, 9 miles of relief sewers (6 in tunnel and 3 in open cut). The work was separated into 10 contracts. Due to hydraulic design requirements and other constraints, the tunnel profile was located generally 65 feet below ground surface within a soft to medium clay strata which skimmed along the top of a very dense glacial till “hardpan” overlaying bedrock. Boulders within the tunnel bore were recognized as a significant, but indeterminate risk. This paper presents a case history of the owner’s contracting strategy for risk assumption and management of the boulder impacts on the project. Actual conditions encountered during construction and contractual adjustments made to address problems are reviewed, and recommendations for future contracts are included.

Jan 1, 2003

By John A. Herbst

Mathematical models of mineral processing unit operations have been developed and used for a variety of purposes. Models, defined as equations which mathematically approximate the behavior of process units, are being employed in simulators to evaluate proposed flowsheets, to investigate flowsheet modifications, to study the effect of variables on circuit behavior, to optimize the performance of circuits off-line, and to compare alternate control strategies (Mular and Herbst, 1978). Models developed for mineral processing operations may be placed in one of two general categories: phenomenological (based on mechanism) and. empirical (based on experimental data only). Dynamic models (including time as a variable) .are useful for control studies, while steady-state models (independent of time) are employed in flowsheet evaluations. Phenomenological models are potentially more flexible and accurate than empirical models. However, models constructed from theoretical knowledge are less easily developed compared to empirical expressions fitted statistically to experimental data. The latter apply only over the range of data acquired. Most often, models used in practice are the result of a combination of theoretical and empirical approaches.

Jan 1, 1979

By R. F. McFarlin, H. E. El-Shall

Since its inception, the Institute of Phosphate Research has examined every promising proposal in order to find an economical, practical and environmentally sound method of dewatering phosphatic clays. The in-house development of the FIPR/DIPR process (DIPR = Dewatering Instantaneously with Pulp Recycle) would appear to answer that quest. When small amounts of fibrous materials are mixed with clay slurries and flocculent, rapid dewatering occurs. Clay solids contents of 20 to 25% can be attained by simply rolling the clay mass down an inclined screen. Higher solids (>40%) are reached by physically pressing the cake; e.g., with a belt press. Because mechanical pressing devices are too expensive for phosphatic clay treatment, FIPR has developed the "sandwich" method of simultaneously dewatering the phosphatic clays and reclaiming the mine cut, as well as a second alternate, the "median strip" proposal. Economic projections of these bench-scale alternates suggest that the FIPR/DIPR process should be no more costly than present practice, when credit is given for the simultaneous reclamation accomplished.

Jan 1, 1993

By M. T. Ityokumbul

The effect of reaction conditions on the desulphurization of oil sand coke residues has been studied. The variables investigated were temperature, reaction time, heat transfer resistance, and mode of caustic soda addition. The results obtained show that oil sand coke desulphurization increases with temperature, reaction time, and heat transfer rate. In an oxidative environment, coke combustion during molten caustic leaching (MCL) commences at temperatures above 500°C. The mode of caustic addition has no effect on coke desulphurization.

Jan 1, 1995

By William A. Vogely, John E. Tilton

INTRODUCTION Mineral commodities are normally separated into three generic classes-metals, nonmetals, and energy minerals including oil and gas as well as the solid fuels. Metals, the focus of this chapter, encompass a large number of different substances. The U.S. Bureau of Mines, for in- stance, has commodity specialists following trends in over 40 metal products of importance to the country's economy and well being. Ranging from aluminum to zirconium, the metals display an incredible degree of diversity. Some such as lead are heavy, others such as magnesium are light. Some such as copper are good conductors of electricity. Others such as silicon are semiconductors. Mercury is found in liquid form, while some metals melt only when heated to extremely high temperatures. Iron and steel, aluminum, and copper are consumed in particularly large tonnages in a multitude of end uses, while many minor metals are needed in only small amounts in a few highly specialized applications. The use of some metals can be traced back into history for millennia, indeed back to the bronze and iron ages, while the commercial consumption of aluminum and other newer metals is less than a hundred years old. Some metals are extracted from large open pits, others are dug out of deep underground mines, and still others are processed from the sea. Mining and processing can be relatively uncomplicated and inexpensive, though in most instances highly sophisticated technology is necessary and the costs are high. Some metals are produced mainly as byproducts of other metals. Some are recovered in large quantities from the scrap of obsolete equipment and demolished buildings. Some are mined in only a few locations and traded worldwide, others are produced in many different countries. Some are sold by numerous firms at fluctuating prices determined on competitive commodity exchanges, others are produced by only a handful of firms and sold at stable producer-prices. This diversity makes the metals interesting, indeed fascinating, to study. Yet, it also poses problems, for each metal in its own way is unique. There is no general model or economic analysis applicable to all metals. Rather each must be considered individually, so that the analysis or model takes explicit account of its particular features. This means that a single chapter cannot begin to cover comprehensively the economics of all metals, and no attempt to do so is made here. Instead, we will concentrate on illustrating the usefulness of relatively simple economic principles, particularly those associated with supply and demand analysis, in understanding the behavior of metal markets. The next section begins by exploring the nature of metal demand. It is followed by an investigation of metal supply- from individual product production, from by- product and coproduct production, and from secondary production. The final section then illustrates the usefulness of the concepts introduced in earlier sections by using them to analyze

Jan 1, 1985

By Edward T. Koch

With the dramatic increase in world demand for basic raw materials, open pit mining is proceeding at an unprecedented rate. A viable demand is the ever tempting Siren's song for increased production or new facilities. When the Siren's lure is viewed against the panorama of today's world economic milieu the concomitant Scylla and Charybdis are seen in the form of high capital cost and high operating cost. If the economic realities of present day open pit mining are to show a proper return on investment, a clear and penetrating eye must be cast upon the area of mine planning. This paper deals with the problem of overburden removal. In almost every open pit mining operation overburden removal is a significant part of the capital cost and operating cost of the total operation. This paper deals with a new and unique method to affect economical overburden removal. Well known to all are the parameters surrounding draglines, shovels, and bucket wheel excavators. All of these machines require a reasonably stable soil to support them and the shovel and bucket wheel excavator require a reasonably stable bank in which to operate. Their reliability, portability and rate of production per dollar of invested capital are good.

Jan 1, 1975

By George D. Roberts

Dams are constructed to retard the flow of water or debris; therefore natural forces are constantly at work to remove such obstructions. To circumvent nature and avoid expensive trouble with a dam requires thoughtful far-sighted planning, careful construction control and vigilant periodic inspections to detect and repair deterioration at its inception. Although the factuality of the foregoing statements is apparent, all too many have failed to consider them in the past as will many in the future. "The economic, but safe construction of dams calls for the highest order of technical knowledge, practical experience and sound judgment." (1)

Jan 1, 1967

By R. R. Klimpel

This paper discusses the effect of water chemistry, reagent type, and other environmental factors on the performance of sulfide mineral size reduction and froth flotation processes. Two specific problems will be discussed: 1) the importance of appropriately utilizing the electrochemical window that is created in the grinding process to enhance sulfide mineral recovery by froth flotation; and 2) the impact of steel grinding media versus autogenous grinding on the efficiency of sulfide mineral flotation with varying thiol collectors and water sources.

Jan 1, 1996

By S. Middlemiss

The Indentation Fracture technique is being developed as a tool for use in comminution and mineral liberation analysis. Fracture toughness measurements for a number of mineralogical materials were made and comparisons were drawn between these and properties measured with the Ultrafast Load Cell drop weight apparatus. The technique has also been used as a probe to quantify differences in fracture properties at different areas in the microstructure of a material. In both a Utah limestone and a South African quartzite, material near a grain boundary fractures very differently to that in the bulk. Ongoing work is ultimately aimed at producing a comprehensive fracture model for a multi-mineral system based on its micro-fracture characteristics.

Jan 1, 1994

By G. R. Giuliani

Hanna Mining Company's Groveland Mine is located in the Upper Peninsula of Michigan. The low grade iron ore deposit consists of a mixture of magnetite and hematite with chert, jasper, quartz and various iron silicates (1). The ore is beneficiated by magnetic separation and anionic flotation of the iron minerals with chemical depression of the silica. The magnetic concentrate makes up about 75% of the concentrate. The concentrate is pelletized at the rate of 2.0 million LTPY of pellet production. The concentrator facilities were started up in 1959 and the concentrate was marketed as sinter feed until 1963 when the concentrator was expanded and the pelletizing plant was added. The pellet plant now consists of regrinding, elutriation, filtering, balling and induration. The pellet machine is a straight grate which employs updraft drying and cooling and downdraft drying, preheat and firing. It is necessary to regrind the concentrate before pelletizing. The con-centrate is 60% passing 325 mesh, with a surface area of ±lOOO cm2/Gm, and must be ground to about 83% passing 325 mesh, 1600 cm2/Gm blaine surface area, for pelletizing. The energy for regrind has been reduced from 12.5 KW per LT to 8.80 KW ate of 2.0 million per LT. This was the result of changes made in the concentrator where originally a coarse spiral concentrate, instead of the magnetic concentrate which is screened on fine screens to reduce the coarse fraction and prevent overgrinding before flotation, was produced. Also in 1968 an additional concentrating line was added to the concentrator which employs more grinding power than the other three lines. The demand for a high iron grade and lower silica pellet resulted in the investigation of different schemes of upgrading the reground concentrate which had more iron values liberated during grinding for surface area. The reagentized material presented many problems, mainly in selectivity trying to flot the iron and with high reagent consumption having to dereagentize the concentrate for amine silica flotation, in the various flotation systems tried. Tests were then conducted with elutriation (2) which proved satisfactory by removing the lower specific gravity, fine gangue material from the heavier material with the

Jan 1, 1977

By Yves C. Lizotte

Although blasting remains the most inexpensive method of fragmentation in hardrock mining, the significance of the costs of blast-induced rockmass damage in terms of mining efficiency and safety is becoming increasingly recognized. There is no straightforward and systematic method of adequately measuring blast damage in on-going mining operations. This paper considers various techniques available to measure blast damage, making particular reference to recent underground hardrock mine studies. It concludes by proposing a damage audit procedure for integration into routine mine production control.

Jan 1, 1996