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By Peter Hornby, Maurice Craig, Franklin G. Horowitz, Don Bone

We have developed a high-performance, flexible scheme for interpolating multi-dimensional data. The technique can reproduce exactly the results obtained, for example, from Ordinary Kriging and related techniques in 3D, or from Thin-Plate Splines (Briggs' minimum-cuwature algorithm) in 2D. Moreover, com- pared to traditional implementations of these algorithms, our method enjoys large computational-cost savings. The new approach produces an interpolation that obeys a Partial Differential Equation (PDE). The PDE may arise from physically based arguments, but its form can vary widely. It might be specified only implicitly (as through a Model Variogram), or be nonlinear (although a performance penalty could then apply). While a formal equivalence between Kriging and Splines has been known for some time (Matheron, 1980), the present derivation, from radial basis functions, further illuminates this connection. Thus, for example, we can make explicit the PDEs that underlie some of the Model Variograms most often used in Geostatistics. Besides its practical utility, the work thereby ac- quires a theoretical interest.

Jan 1, 1996

By S. Tuylu, D. Adiguzel, A. Bascetin, E. G. Savas, O. Ozdemir

"Paste Technology has some advantages comparing to other surface disposal methods. With this method, it is possible to pump high concentrated solid materials to very long distances without segregation problem. However, it is known from Literature that pumpability of materials is completely related to rheological properties of the materials. For this reason, in this study, the rheological parameters (e.g. yield stress and viscosity values) of the paste material prepared from Pb-Zn tailings at various solid ratios (60-85%) were obtained in order to determine the pumpability of the paste material. Additionally, slump tests, which are usually used in mining industry, was carried out. Finally, regression analysis was made between the slump values and rheological parameters of the paste material to find a correlation between two independent parameters. The results showed that there is a great correlation between the slump values and the yield stress of the material. On the other hand, there was no correlation with viscosity: ty=430.28-16.877Sv (R2= 0,94; ty: Yield Stress (Pa), Sv: Slump Value (cm)). Based on the results obtained from this study, it can be clearly concluded that the slump values obtained from a simple test can be used to predict yield stress values of paste materials. INTRODUCTION Recently, surface disposal of mining tailings has become one of the biggest problems in mining industry in terms of environmental issues. Therefore, several researches have been focused on this subject in order to find a best solution or method for this problem. These studies showed that paste technology has some advantages compared to other conventional methods. Tailings thickened to the extent show no segregation of particles during transportation, and relatively small amount of settling occur post-deposition which are often called “paste” (Cincilla et al. 1997). Paste tailing technology has two applications in the industrial area as underground paste fill and surface paste disposal. Paste tailing technology was first started to be used in Grund mine, Germany in the late 1970s (Grice, 1998). Process tailing material, water and - if needed - cement materials, which are the components of the paste, must be blended to obtain a homogenous mixture suitable for pumpability. Consistency behavior of the paste material is determined using a conventional sedimentation cone concrete test (slump). Meanwhile, the slump value of the paste must be between 200 and 250 mm for surface applications (Newman et al., 2001). Additionally, in the case of underground paste system, the optimum slump value must be between 150 and 200 mm. On the other hand, the water content and density of paste at certain slump value change depending on the amount of fine particles in the tailing sample. While moisture of the material will be high, its density will be low because of surface area of particles which increases with decrease in particle size (Meggyes and Debreczeni, 2006). For pumpability of the paste to long distances, slump value of the paste must be good enough to be accepted for use of surface paste disposal. Paste material has a yield stress because they show non-Newtonian behavior and generally is classified as a Bingham plastic fluid. (Cooke, 2008; Theriault, 2003). In addition, the appropriate viscosity value of the paste along with the yield stress must be between 100 and 250 Pa (Bascetin et al., 2013; Bascetin et al., 2014; Bascetin et al., 2015)."

Jan 1, 2016

By John G. Oldsen

During the last several years, implementation of trusses, in lieu of wood cribs, has been successful for supplemental tailgate support in the Pittsburgh seam. This paper reviews the truss support system provided by the new high strength 0.6" tensioned cable truss, which is now also being used in cribless tailgates. Cable loading and roof deformation were monitored to evaluate roof and floor performance. The test results indicate that the cable truss system successfully controlled the roof and floor during the first and second panel extraction. This paper will describe the advantages of cable trusses and their load transfer mechanism as well as mine evaluation.

Jan 1, 1997

By I. B. Tulu, M. M. Sears

"In 2015, 40 longwall mines provided nearly 60% of the US coal production from underground mining methods. This represents a substantial, yet gradual increase from just under 50% over the last 5 years. As a result of this increased production share, the percentage of ground fall related fatalities in longwall mines has also increased when compared to all US underground coal mines. Additionally, about 80% of ground fall related fatalities have occurred in areas where the roof was supported. In an attempt to better understand the status quo of current US longwall support practices, a sample of 21 longwall mines were visited, representing about 40% of the currently active longwall mines in 4 of the 5 major US longwall producing regions. The resulting data was obtained from a wide variety of overburden depths, geologic conditions, mining heights, ground conditions, support practices, and gateroad configurations. The data collected is reported using both qualitative and quantitative methods. The results from the research update previous efforts in classifying mining accidents and injuries as well as current support practices. This data provides a necessary background for future research aimed at further reduction of ground fall accidents and injuries. INTRODUCTION Maintaining ground stability in gateroad entries is essential for longwall productivity and safety (Campoli, 2015). In 2015, 148 unintentional roof falls were reported in US longwall mines. About 34% of these resulted in mineworker injuries. Safety considerations not only include injury from roof and rib falls but also egress from the longwall face during an emergency (Mucho et al., 1999). Over the past 30 years, a number of researchers have studied longwall tailgate support performance (Mirabile, 2015). This research aims to take a snapshot of the ground support installed in modern US longwall mines and provide a supplement and update to the overview provided by Barczak (2005). This will provide a framework for future research into improving gateroad support systems. BACKGROUND Large unplanned roof falls at or above the primary support or those impeding travel and/or ventilation must be reported to the Mine Safety and Health Administration (MSHA). Reportable roof falls, normalized based on production in million metric tons, generally relate to the amount of roof exposed during the mining process (Pappas and Mark, 2012) and provide an evidence-based statistical background for this review of current support practices. Figure 1 shows the reportable roof fall rate in US underground longwall mines for the period 2006-2015 (MSHA, 2016). Over the past decade, roof fall rates have shown a gradual decrease with numbers now at a rate nearly half of what was observed just five years ago. However, over the past few years, roof fall rates in US longwall mines appear to have stagnated at levels just over 1 per 2,000,000 tonnes mined."

Jan 1, 2017

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By Julio C. Martinez, Jeffrey L. Rice, Hayden Weschler

This paper details the extensive underpinning required to hold up the 39th street Bridge while demolishing its massive support piers and building a 30ft deep Cut/ Cover RR tunnel beneath it. The underpinning/SOE support required the construction of 16 large hand dug pits 36ft deep that were reinforced and concrete filled. In addition, an extensive steel support system was tied into the bridge super structure. All of the underpinning/tunnel construction was done while a 110ton crane sat directly atop the heavily trafficked – 66 ft. wide bridge. The tunnel excavation, concrete lining and final bridge pier support work will also be presented. All work was done within 5ft of active mainline tracks and that required tight grouting behind all lagging to eliminate any track settlement.

Jun 13, 2021

By A. K. Sheik

A small underground mine in northern Idaho was used as an experimental facility for studying the role of water in the analysis of mine opening stability. Laboratory test data, borehole measurements and geological mapping assisted in constructing a coupled finite element model of the rock mass. The model was used to make quantitative estimates of: 1) rock stress, strain and displacement changes, and 2) water pressure and flow velocity changes that occurred during historical mining. Stope cuts and wet fills were included in the analysis. Stability of crown pillars between stopes was of particular interest. The relatively low effective stress and high rock mass strength showed that water pressure changes were of no great consequence in agreement with experience. The computational tools used in the analysis may be applied to other wet mines with appropriate changes to site-specific input data.

Jan 1, 1999

By R. K. Will

An inactive mining operation in northern California is known to be a source of acid mine drainage and heavy metals which have impacted adjacent creeks. Elevated concentrations of copper and zinc are a concern to aquatic populations, particularly steelhead trout and salmon downstream in the Sacramento River. Previous regional geological surveys of mineralization by the U.S. Geological Survey located and mapped outcrops of massive sulfides and gossan. Recent investigations indicate that a substantial amount of the metals in the local creeks are due to natural causes. The investigations include locating and mapping surface and subsurface minerals, soil and water sampling, and chemical analysis. Groundwater, seeps, and surface water were also sampled and analyzed. A water balance was conducted on a sub-basin level following delineation of surface water drainage and groundwater divides. A chemical mass balance incorporated metal concentrations and water volumes and was then used with other data to determine the contribution of metals from natural versus mining-related causes.

Jan 1, 1998

By T. W. Camm

The Bureau of Mines conducts studies of the economic impacts of regulations on federal lands. These studies are part of the Bureau Potential Supply Analysis (PSA) program. To meet the needs of these studies, a methodology was developed to estimate operating and capital costs for a mineral deposit given its tonnage, grade, and depth. The format for the cost models in this study was developed at the Bureau's Western Field Operations Center (WFOC), Spokane, W. A., for studies of known and undiscovered resources on Federal lands. These cost models are described in a Bureau publication by Camm (1991).

Jan 1, 1993

By E. F. Draskovich

In 1984 a high temperature heat recuperation system was installed in the pellet plant of the National Steel Pellet Company located in Keewatin, Minnesota. The system is similar to those of Cleveland Cliffs Empire and U.S. Steel's Minntac operations. It recovers hot process air from the cooler by induced flow, and directs it to an intermediate zone between the drying and preheat zones on the grate machine. This system recently underwent further modifications in April 1985, following initial operation in 1984. The M. A. Hanna Company, which manages the property, developed the design criteria and made the subsequent recommendations for modification through its research facility in Nashwauk, Minnesota.

Jan 1, 1986

By Donald E. Zipperian

It has been recognized that froth flotation of mineral particles utilizing rising flow of micro size air bubbles, counter-current to quiescent falling flow of particles in a column type cell, provides a unique mechanical atmosphere conducive to extension of froth flotation process to much coarser and finer particles sizes than possible with mechanically agitated and aerated cells. 1,2,3,4. This paper describes metallurgical results obtained at several plant installations of large capacity commercial size Deister FLOTAIRE® Column Flotation Cells. These cells utilize air aspiration into surface tension lowered water to generate micro size bubbles. Operating costs, power, wear, and scaling characteristics of rougher, cleaner, and scavenger units are compared with mechanical units. Problems encountered and scale up criteria developed when increasing from 0.20m(8inch) diameter pilot cells to 2.42m(96inch) commercial cells are discussed.

Jan 1, 1985

By C. A. Summers

The U.S. Bureau of Mines applied process mineralogy to investigate a lead and zinc deposit located near Story Creek, Colville Mining District, Alaska. Mineralization is hosted by the Kayak Shale in veins, veinlets, and breccia. Sphalerite and galena, with supergene anglesite, occur in symmetrical quartz veins and between breccia clasts. The study sample analyzed 2.11 percent Pb, 5.37 percent Zn, 0.014 percent Cu, and 1.2 oz/ton Ag. Analyses of crushed products showed that 33 percent of the sample weight, and more than 50 percent of the Pb and 65 percent of the Zn, are in the minus 850 µ m fraction. Liberated grains of sphalerite and galena were found in crushed products finer than 300 µ m. Beneficiation tests indicate the material is amenable to processing by traditional gravity and flotation techniques.

Jan 1, 1993

By F. S. Knoll

Magnetic separation employing superconducting technology is now accepted within the Kaolin processing industry, proving the value of this technology and its ability to operate reliably even at the most remote site. Developments in superconducting magnet engineering, including cryogen free operation, combined with experience in mineral processing enables new forms of Wet and Dry superconducting magnetic separation to be developed. Applying the high magnetic force advantages at 5 T else available from such magnets to other materials is now a reality. High magnetic force mineral separating system developments are reviewed allowing the mineral processor to take advantage of a technology that is no longer confined to the laboratory.

Jan 1, 1997

By A. S. Hall

Significant pyrite often does not dissolve in the Sobek (1978) nitric acid extraction; therefore, the standard conservative approach is to estimate pyrite using sulfur present in the sum of the nitric acid and residual sulfur fractions. Alunite, when present, appears as residual sulfur. Because alunite does not generate acidic effluents, overestimation of AGP can occur if all residual sulfur is assumed to be undigested pyrite. Evaluation of 16 samples from the Florida Canyon Mine revealed that petrographic examination coupled with a modification of the Sobek method to include a 6 hour hot (250°F) 'nitric acid extraction resulted in a more accurate estimation of AGP.

Jan 1, 1999

By Douglas M. Smith

The town of Tayoltita, Durango is located at the bottom of the 2000 m. deep Rio Piaxtla canyon on the axis of the rugged Sierra Madre Occidental mountain range. Throughout most of the year access to the town is restricted to travel by mule or STOL aircraft. Silver and gold have been produced from epithermal veins in the north side of the canyon since 1757. During the last seventy-three years more than 4,588,000 kg. of silver and 76,322 kg. of gold have been produced from approximately 6,000,000 metric tons of ore. The Tayoltita mine is developed within a fault block bounded by normal faults which strike north-northwest and have opposing dips. A thickness of at least 1300 meters of late Cretaceous or early Tertiary volcanic rocks is exposed in the mine. These range in composition from andesite to rhyolite. Andesite predominates in the upper 750 meters of the section. The volcanic rocks were passively intruded by quartz-monzonite and andesite stocks during middle (?) Tertiary time. Mineralization spatially and temporally (?) related to the stocks occurs along the east boundary fault and in intersecting footwall fissures which strike east-west and northeast. Ore was deposited over a vertical range of up to 600 m. prior to tilting of the volcanic rocks 35 to 45° to the east. With few exceptions, the ore bodies are found within the lower 400 to 500 m. of the andesite. Argentite (acanthite), stromeyerite, jalpaite, electrum and native silver are the principal ore minerals. They occur in gangue composed of one or more of the following: quartz, calcite, bustamite, adularia, chlorite, and albite. Base-metal sulfides make up less than 1.5 percent by weight of the ore.

Jan 1, 1974

By Peter F. Howard

The lower Middle Cambrian phosphorite deposits of the Georgina Basin shown in Figure 1 were found in the period 1966-1968 by three companies, namely, International Minerals and Chemical Corporation, Continental Oil Corporation and Broken Hill South Limited. Of these deposits the significant ones are Duchess, Sherrin Creek, D Tree, Lady Annie, Lady Jane, and Wonarah which together aggregate several billion tons reserves of phosphate. Due to the economic factors of freight costs to the coast and softening of the world market price for rock phosphate, none of them is in production, nor is any in the development stage. This paper reviews the historical background to the discovery of these deposits and then deals principally with the discovery of non-outcropping phosphorites in the Barkly Tablelands of Northern Territory by the interpretation of gamma radiation logs of abandoned water bores.

Jan 1, 1971

By A. A. Densmore

Telluric Current is that portion of the electric field observed at the surface of the earth which is of an alternating nature, and which is related to solar activity and events in the ionosphere. The primary electromotance which drives the telluric current is the result of the induction process associated with time variations in the earth's magnetic field. The relationship between the electric and magnetic components of this electromagnetic field depend upon the conductor. For our purposes, we are dealing with frequencies f in the range

Jan 1, 1972

By M. L. Smith

SAG mill throughput is often a bottleneck in increasing metal productivity. Improved size distribution control in the mill feed can be used to increase mill production. This can be accomplished by controlling blast fragmentation as a function of energy input and rock characteristics. Such an approach requires the integration of rock fragmentation and comminution modeling. The optimal mill feed size distribution is determined by adapting a population balance comminution model to a measure of rock hardness or fragility which is also relevant to the rock fragmentation that is achieved by blasting. The relation between the size distribution and fragility of the feed and of the mill's product and the critical size in a SAG mill is examined.

Jan 1, 1993

By W. D. Keller

Scan electron micrographs, SEM's, will be shown of representative refractory clays from Missouri deposits, with counterparts from other localities. The story is in the pictures, ("1000 words in each picture"), but clay types include the following. Plastic, semi-plastic, and semi-flint "fire clays" of Missouri have textures which appear to retain certain relic texture of ball clay. Flint clay is composed of tightly interlocking packets, sheaves, and books of kaolinite. Diaspore and boehmite mineral textures characterize those "clays". Surface-boulder diaspore shows very pronounced recrystallization and crystal enlargement from original, unexposed first-grade diaspore.

Jan 1, 1977

By G. Vallebuona

Currently, empirical models are used for predicting the hydrocyclone performance in terms of capacity, cut size (d50,c), water split and partition curve. These models, for example those of Lynch and Plitt, have been developed and checked for hydro cyclones with diameters larger than four inches. For smaller diameter hydrocyclones little empirical modelling has been done. This paper reports extended experimental research on small hydrocyclones. For these cyclones, the suitability of existing empirical models has been checked and their accuracy compared. Modifications of the existing models equations are proposed, improving their predictive capability for the small cyclones performance.

Jan 1, 1994