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By Norman F. Schulz

Representative sample s of typical manganiferous iron ores from the Cuyuna Range, Minnesota, were reduced to the metallic iron state at temperatures just short of fusion with an excess of coke in the manner prescribed by the R-N Direct Reduction Process. The magnetic separation characteristics of the reduced ores were determined at several grinds by means of the Davis magnetic tube concentrator. The efficiency of metallic iron concentration by magnetic separation was a direct function of the degree of metallization of the ore sample and of the degree of liberation attained in grinding. Some improvement of liberation characteristics was observed if a small amount of sodium chloride was present in the ore during reduction. Despite the extremely fine -grained structure of the crude ores, iron concentrates containing more than 90% Fe at iron unit recoveries of 90% or more were obtained from well-metallized samples of three of the four ores tested. The rejection of manganese to the tailings corresponding to such separations varied from 80 to 95%.

Jan 1, 1967

By J. A. Madonna

Independent prospectors and small to large-scale exploration company personnel have requested, and are in need of, guidance in geochemical field sample collection methods which will provide the most reliable results during chemical analysis. In cooperation with analytical laboratories, experienced geochemical exploration scientists and mining companies a systematic collection procedure has been developed. The procedure consists of collecting uncontaminated, water, sediment and rock chip samples of the appropriate quantity and/or dimensions to meet the needs of analysis.

Jan 1, 1999

By J. C. Harrison

Eldorado Gold Corporation of Vancouver, B.C. owns and operates three gold mines. The Sao Bento underground gold mine in Minas Gerais State, Brazil produced 105,907 ounces in 1997. The La Colorada and La Trinidad open pit, heap leach mines in Mexico produced over 83,000 ounces in 1997. With a deteriorating gold market plaguing the industry throughout 1997 Eldorado had to take critical measures at each mine to enhance gold production while lowering cash operating costs. Each mine had its own unique problems to confront. This case study will discuss three distinct courses of action taken at the three mine sites.

Jan 1, 1999

By E. D. Sehnke

The refractory materials industry provides the largest commercial market for nonmetallurgical grade bauxite. Refractory grade bauxite is prepared from bauxites having low iron, titania, and alkali content by calcining at temperatures near 1,650° C. Although there are substantial bauxite reserves in the world, premium grade bauxite ores suitable for use in refractory applications are limited to only a few specific sources, primarily in Guyana and the People's Republic of China. Consumption of bauxite for refractory use is closely associated with the production and consumption of primary metals, in particular iron and steel. Barring major disruptions within the principal producer nations, sufficient supplies of refractory bauxite will be available to meet world demand well into the next century, and raw material costs will continue to determine the availability of markets for bauxite-based refractory products.

Jan 1, 1992

By A. W. Khair

This paper presents an analysis of respirabie dust generation due to the action of a continuous miner. Underground coal cutting by a drum-type continuous miner was simulated in the laboratory using a specially designed unique automated rotary coal cutting simulator (ARCCS). An analysis of -400 mesh particles was done on gravity collected material. Samples of entrained dust were collected through the use of cascade impactors. Both samples were analyzed for size distribution and particle shape. Using the simulated coal cutter permitted variation of operating and in-situ parameters to provide information on the effects on generation of -400 mesh particles. In these tests coal blocks with an approximate dimension of 18 in. x 15 in. x 6 in. (45.7 cm x 38.1 cm x 15.2 cm) were first subjected to confining pressures, equivalent to in-situ conditions. Such blocks were then cut by the cutting head of the ARCCS, thus simulating the action of the continuous miner in underground coal mining. During the tests under a particular set of in-situ and operating parameters a number of other parameters such as 1) penetration of bit into coal, 2) penetration resistance (thrust and cutting pressures), 3) rotating velocity of cutting head, and 4) acoustic emission activity in the coal block were monitored. After each cutting cycle the fractured surfaces were photographed and a velocity survey was conducted by using a sonic technique. At the end of each experiment the cutting paths of the bits in coal were photographed using an optical microscope with an attached camera.

Jan 1, 1985

By Ravi Shah, Augusto Lucarelli, Daniele Peila

"In mechanized tunneling the annular gap between the segmental lining and the surrounding soil caused by tunnel driving, must be backfilled almost instantaneously with an adequate grouting mortar. The objective of this research is to perform a fully three dimensional modeled parametric study using FLAC 3D and evaluate the effects of backfill grouting on the tunneling performance. The research focuses on comparisons between different injection materials and state-of-the-art Bi-Component grout and their effects on the settlements on the surface. The research consists of testing a regular situation of tunnel excavation using a shielded machine with face under pressure. The tunnel dimensions and the soil properties are selected as close as possible to the reality and based on Turin Metro case. 1 INTRODUCTION Excavation of tunnels in urban areas can induce ground movements, which have negative effects on existing structures. In such scenarios, shield tunneling has become a well-accepted construction method in various ground conditions. It is characterized by relatively complex interactions between the soil, the tunnel boring machine (TBM) itself, the tunnel lining and the tail void grout. The problem to control the settlement depends on the face pressure, ground properties and back filling procedure and material of the tail void. The face pressure acts against the front to guarantee the face stability. In case of EPB TBMs the stability of the tunnel face is ensured through the excavated soil itself, which is conditioned and is maintained in compressed state within the excavation chamber. When excavating with TBMs a tail void is created between ground and the lining (Fig.1) after the TBM excavation and ring assembly that must be backfilled instantaneously by injecting the backfill material through the TBM’s tail shield. The process is of primary importance as it reduces the surface settlements and creates an immediate link between the ground and lining, sealing against ground water and leakage, reducing the differential movements between segments and providing long-term stability. The most used backfilling materials are: Inert mixtures that do not contain cement instead sometimes they are replaced by fly ash or other substitutes. A typical design of an inert mortar consists of sand, fly ash, bentonite and water. Pea gravel, which is constituted of granular materials with grain size ranging from 8 to 12 mm. This mixture is highly recommended for tunnels being constructed in rock mass with little deformation rates.Cement mortar is composed of cement, water, aggregates and sometimes bentonite. Cement controls the principle mechanical property of the mix, which can reach high values of 15-20 MPa in 28 days. The aggregates contribute towards the shear strength and reduce the pumpablity of the mix (Thewes and Budach, 2009). The reduced active systems have a cement content of 50-100 kg/m3, whereas the active system the binder component derives full hydration with cement content of over 200 kg/m3 ."

Jan 1, 2016

By P. Aparicio

The rheological properties of five kaolins, isostatically pressurized at 4 x10 Pa for 10 min in the presence/absence of water, was determined. Under dry conditions, measured viscosity values either decreased or remained the same. After treatment under wet conditions, measured viscosity values were 30-60% higher at high shear and 50-60% higher at low shear. These results correlate with variations in nanomorphology and structural order. Dry compaction degraded kaolinite crystals but wet-pressing appeared to cause an increase in the proportion of euhedral crystallites and a decrease in deformed crystals. Dry compaction decreased the low-defect phase proportion (ldp), but in contrast, the ldp in wet-treated kaolins remained constant or increased. Results show that hydrous pressure treatment produces a change in viscosity of kaolin suspensions, yielding the potential for improving paper coating performance, whereas anhydrous pressure treatment decreased or maintained the viscosity.

Jan 1, 2010

By Steven J. Schatzel, Mark M. Mazzella, Robert A. Kimutis, VASU GANGRADE, James D. Addis, Marcia L. Harris, Mayley Guitard

Researchers from the National Institute for Occupational Safety and Health (NIOSH) evaluated the impact of potential shale gas well breaches and subsequent gas inflow on selected mine ventilation systems of operating longwall panels using a 1:30 scaled Longwall Instrumented Aerodynamic Model (LIAM) and Sulfur hexafluoride (SF6) as a tracer gas. A series of tests were performed at 340, 400, and 500 cfm inflow levels utilizing different mine ventilation scenarios. Results suggest that the breached gas can be diluted to meet statutory levels when the longwall panel is adequately ventilated. The results enhance the understanding of the gas inflow and mine ventilation system interaction and provide critical information to the industry and regulatory agencies for improving miners’ safety.

Feb 1, 2024

By B. Kolonja

This paper considers simulation of truck dispatching system designs using maximum expected production of the truck-shovel system as the measure of performance. Two methods are utilized, multiple comparisons with the best (MCB) and the combination of MCB and the variance reduction technique known as common random numbers (CRN). These two techniques are compared via simulation experiments. The results show that the combined procedure of MCB with CRN is the superior tool to reduce the total number of replications needed to ensure the specified probability of correct selection over the finite number of designing systems. In this case study, MCB with CRN reduces the variance by 29% and the number of required replications by 48%. Also, the MCB with CRN procedure narrowed the confidence interval by 18%.

Jan 1, 1994

By D. D. Harbuck

Previous studies at the U.S. Bureau of Hines have shown that only 70 to 80% of the germanium in domestic zinc process residues can be extracted during H2S04 leaching. To increase germanium extraction, the Bureau developed and researched the hypothesis that minor amounts of germanium and zinc silicate, both present in zinc calcine, dissolve during the leaching stages of zinc processing, forming soluble germanium and silica gel. This silica gel then selectively adsorbs germanium from solution, rendering the germanium insoluble. Testing showed that as the amount of silica gel formed increased, the amount of insoluble germanium in the zinc residue increased. Several processing alternatives are presented for overcoming this problem.

Jan 1, 1991

By PDF

Previous work has shown that significant, free milling gold values exist in the Ryan Lode ore. This project used pilot scale equipment to estimate the percentage of gold recoverable by gravity methods from the circulating load of a conventional, closed-circuit, grinding mill. The pilot scale flowsheet employed three stages of gravity concentration, hydraulic classification and batch grinding to simulate a full scale milling circuit. 172 kg (379 lbs) of Ryan Lode ore were processed, having a head grade of 4.8 g/metric ton (0.14 oz/ton). Results showed that simple gravity methods are capable of recovering 45-50% of the gold values in a concentrate grading in excess of 3430 g/metric ton (100 oz/ton). Of the remaining gold values reporting to the classifier overflow solids (80% passing 70 microns, 3.1 g/metric ton (0.09 oz/ton)) 89% were recovered from 48 hour bottle roll tests.

Jan 1, 1995

By David F. Becker

Two-dimensional, finite-difference elastic modeling aids in planning an optimum seismic-acquisition scheme to define the extent of subsurface cavities resulting from in situ gasification. To understand the seismic effects of a cavity, two models are compared and contrasted. Model A consists of a low-velocity layer (LVL) in a half space; Model B contains a rectangular water-filled cavity in the LVL. Amplitude differences are the dominant effect on the surface records for each model. Cavity resonance and diffraction effects are more definitive in vertical seismic profiles (VSP's) and in a "snapshot" of the wave field. Interpretation and subtraction of corresponding records for both models shows the need for pre- and post-gasification seismic recording. Also VSP data are more informative than surface records.

Jan 1, 1983

By F. Montgomery Lyon

Pyritic sulfur in coal occurs as discrete mineral particles, and its liberation and physical rejection is the primary target for coal desulfurization. An acceptable solution to the pyrite removal problem from fine coal is not found in the standard methods of coal cleaning such as jigging, heavy-medium separation, tabling, and hydro-cycloning. Although fine coal is an ideal size for froth flotation, this method, as currently practiced is also unsuitable as the fine pyrite usually floats with the coal. One possible solution to this problem may be the froth flotation of pyrite from coal. This reverse flotation scheme would have the major advantage of removing both free pyrite and locked pyrite-coal combinations. With this possibility in mind, we have, as a first step, compared the flotation and adsorption. characteristics of an ore-pyrite and coal-pyrite with potassium-ethyl-xanthate as a collector 1 Related Research. The action of ethyl-xanthate on coal has been studied 2 by Horsley. He measured the contact angles of coal in distilled water and in the presence of purified ethyl-xanthate. The results indicated that the xanthate was not adsorbed by the coal. Additional contact angle data were obtained to determine the effects of cupric, ferric, and ferrous salts on the system. Then either the ferric or cupric salts were in, solution with the xanthate, there was an increase in the natural contact angles of the coal. This indicated that these heavy metal ions activated the flotation of the coal with xanthate. However, ferrous iron did not act as an activator. Horsley stated that the most attractive explanation was that the xanthate is oxidized to dixanthogen in the presence of the ferric and cupric ions.

Jan 1, 1971

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 William J. Dimond

Computor analysis has opened a new world of information for the mining of resources. This paper is directed at the mining of coal. The same procedures apply to most mining projects. The available facts when evaluated against the variables produce the answers. The project must be carefully analyzed, so that the facts can be organized in a data file. The file can be expanded as additional information is obtained during the entire life of the mine. If the mine is pre-planned, the file will be expanded in an orderly fashion and updated information will be available at all times. The development of a property goes through several phases; Exploration, Economic Analysis, Development, Production, and Reclamation. Each phase is an expansion of the data file. The validity of the answers is directly related to the accuracy and quantity of available data. The basis for a data file is horizontal position, and elevation of each piece of information. A coordinate system and datum are reference for a digital (X, Y and Z) position in a spatial system, a three dimensional digital model of the mine. The current practice is to use the State Plane Coordinate system and elevations as established by the U. S. Coast and Geodetic Survey. Each state has adopted this system by law. In the event there is litigation, it is an advantage to have the data on the legally recognized system. The control must be expanded so that all data can be assigned a digital position, and planned to fulfill the requirements for all phases of the mining operation. The project must be analyzed to insure that the objectives can be achieved without duplication or loss of time. sufficient data must be available to reach each required level of information. The coal data can be defined in two categories, spatial

Jan 1, 1977

By William Petruk

Lithium bearing lepidolites from three deposits in the province of Goias in Brazil were investigated to determine whether there is a correlation between the lithium content of the mineral and the colour of lepidolite and associated tourmaline. Such a correlation can be a useful guide to field geologists for outlining high grade ore zones. It was found that mauve-pink lepidolite associated with pink tourmaline, and brownish lepidolite associated with black tourmaline have high lithium contents, but the colour of lepidolite is not due to lithium. The pink colour of lepidolite and tourmaline is likely to Mn3+, and the brownish tint of lepidolite and black colour of tourmaline to Fe3+. Lepido lites appear to be lithium-rich when the lepidolite and associated tourmaline contain relatively high amounts of Mn3+ and/or-Fe3+.

Jan 1, 1985

By L. Alan Weakly

The purpose of this paper is to present a viable method of reinforcing rock pillars by utilizing fully grouted reinforcing steel and a cement - fly ash mortar. Although the fully bonded bolt concept is not new as exemplified .by the present widespread use of resin bolts within United States mines and by the use of cement grouted reinforcing used as back pins in the Kiruna Iron Ore Mine in northern Sweden, (1)(2) the method of stabilizing mine pillars with fully bonded reinforcing is new. This method, called the "grout-rebar system", was first incorporated at St. Joe Minerals Corporation's Fletcher Mine in December of 1972. The system was used on an emergency basis before extensive research on the mechanics of the system could be completed. Since December of 1972, however, approximately 206 pillars have been reinforced at Fletcher and the system is currently being used on a regular basis at two other St. Joe mines and at two competitor mines in the area. Basically, this paper is a case study of the efforts, research and results of utilizing the grout-rebar system, on a selective basis, at the Fletcher Mine. In addition to information about the system, this paper will explain in detail the three rock mechanics instruments developed by St. Joe and used to measure and monitor rock movement to validate the grout-rebar system.

Jan 1, 1976

By M. C. Rockwell

There are approximately 1,800,000 t of discarded dolomitic-limestone tailings from the Gays River lead/zinc mining operation in Nova Scotia. Neutralization effectiveness similar to an agricultural grade limestone and low contents of residual metals make the tailings a suitable source' of soil conditioner material for the local market. However, the fine particle size, 98% passing 147µm, and a high moisture content make their handling and application difficult. Agglomeration of the tailings into relatively small hard pellets was investigated and difficul¬ties were overcome. Pellets with a range of pH values and various amounts of soil nutrients and moisture content less than 10% were obtained, from tailings containing 20% initial moisture, through the addition of less than 15% selected materials.

Jan 1, 1985

By J. G. Groppo

A beneficiation process has been developed to provide selective separation of unburned carbon from high LOI fly ash. Previous reports of utilizing froth flotation to achieve selective separations required long residence times and high reagent costs. A proprietary reagent system has been developed to address both of these limitations. Based on the results obtained from laboratory and pilot-scale investigations, a flowsheet design has been developed to produce two distinct usable products from class F fly ash; low LOI ash and a high carbon product suitable for reburning or further upgrading. A process flowsheet and description are presented.

Jan 1, 1996

The structure of a mine ventilation network (M.V.N.) can be represented graphically using either the mine plan (map) itself or a number of other types of diagrams. In the U.S., the two most common approaches are the line and the schematic diagrams (see Figures 1 and 2). The purpose of this paper is to introduce another type of diagram, called the canonical diagram (6). The method of M.V.N. representation which uses canonical diagrams is used extensively in Europe, and especially in Poland, where it was developed. The canonical diagram is a noncalibrated topological image of a ventilation system. It gives a simple representation of the ventilation network, allows for the classification of currents within it and enables rapid computer analysis and computation, as well as the representation of the results. It is especially useful in studying and controlling the air flow, and it may be a life saving tool in conducting rescue operations during and after mine fires.

Jan 1, 1986