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By Downing Terry L.

Dry mineral beneficiation methods have been developed for separation of borate minerals from montmorillonite claystone gangue. The methods include the use of newly developed dry high intensity magnetic separators. The application of these methods has the potential for economic benefit at U.S. Borax Inc. in three areas: ? Processing surface impoundments (ponds) material. ? Pre concentrating ore to be fed to primary refinery. ? Concentrating borate minerals to produce potential products.

Jan 1, 1995

By K. Louk, E. Gilliland, N. Ripepi, M. Karmis

"Carbon dioxide (CO2) injection in deep unmineable coal seams can enhance coalbed methane (CBM) recovery as well as effectively and permanently store the CO2. Enhanced coalbed methane (ECBM) recovery and CO2 storage capacity can be improved by altering injection parameters including the injection well locations, number of injection wells, and the time and rate of the injection. A sensitivity study was performed with sixteen different injection scenarios on a coalbed methane field in Buchanan County, Virginia to understand the influence of the injection parameters on methane production, CO2 storage and the extent of the CO2 plume. History matching was done for the gas and water production period prior to injection based on field data from an active US Department of Energy funded pilot project. INTRODUCTION The coal structure is a combination of the coal matrix and cleats. In a CBM reservoir, the methane (CH4) is stored in the matrix under adsorption properties, not as a free gas. During CH4 production, the reservoir pressure is reduced and gas is released from the surface of the coal, diffuses through the matrix and transmits to fractures (man-made or natural) via the cleat network. Fractures and cleats are the major parameters that influence gas flow capacity because deliverability of the CH4 to the production well is controlled by the cleat permeability. As gas production continues over time, CH4 desorbs from coal, and coal matrix volume starts to decrease. This volume decrease in the matrix opens up the cleats, matrix shrinkage, which leads to a permeability increase. Several emprical (Harpalani and Schraufnagel 1990a, 1990b; Harpalani and Chen 1995, 1997; Harpalani and Mitra 2010; Pan et al. 2010; Liu et al. 2012; Mitra et al. 2012) and analytical (Palmer 2009; Liu and Harpalani 2013) studies have reported this relationship between pressure and permeability. Those studies showed that permeability is an important parameter in CH4 production performance. Furthermore, during gas production, water is produced through the cleat system as well, therefore gas-water relative permeability must be also considered in evaluating production performance (Gash et al., 1991). In the CO2 injection scenario the opposite occurs because CO2 has a higher adsorption affinity than CH4. CO2 replaces CH4 in the matrix of the coal and increases the volume of the coal matrix, matrix swelling, and results in a permeability decrease. Harpalani and Mitra (2010) concluded in their experimental study that swelling of the coal matrix due to the CO2 injection is two to three times more than the sorption of CH4, resulting in large permeability changes during CO2 injection."

Jan 1, 2016

By Alex Lowson, Dan Tempelis

The Riverside Badlands Tunnel segment of the Metropolitan Water District of Southern California’s Inland Feeder Project, was lined with a segmented concrete primary lining and a welded steel final lining with the annulus filled with Low-Density Cellular Concrete (really a grout). The paper describes a numerical modeling technique that was developed to determine safe grout placement procedures to avoid pipe flotation, and shows the relationship between flotation and the rheology of the liquid grout. Design details of the steel liners are often not well suited to grout placement, and recommendations are given on how to improve this.

Jan 1, 2003

By V. G. Lofftus

Since plant start-up in January 1983, Golden Sunlight Mines, Inc. has implemented several process changes and improvements. Among these are a pulp preaeration circuit and a sand tailings retreatment circuit. The purpose of the preaeration circuit is to reduce reagent consumption during gold dissolution. The sand tailings retreatment circuit was added to recover and process separately pyrite concentrate to maintain acceptable overall gold recoveries with the more refractory sulfide ores. Research and plant operating data along with process and improvement descriptions are presented.

Jan 1, 1987

By J. Chia, M. H. Kobler, J. Cheung, M. J. Robison

INTRODUCTION The Lake Merced Transport is being constructed as part of San Francisco's Clean Water Program. The Clean Water Program, which began in the early 1970's, is designed to control wet weather, storm sewage overflows into the Pacific Ocean and San Francisco Bay. To accomplish this goal, a system of large underground storage and transport facilities, pump stations, modernized treatment plants, and outfalls is being built. By 1991, eighty percent of the system had been completed and was in operation. One of the remaining projects for the Clean Water Program is the Lake Merced Transport. The Lake Merced Transport is located in the extreme southwestern portion of San Francisco, as shown in Figure 1, Project Location. The transport will convey dry weather flow from the existing Lake Merced Pump Station to the Westside Pump Station. During wet weather, the transport will fill with sewage and runoff, with a storage capacity of 36 million liters. The Lake Merced Transport was expected to be excavated entirely within the Colma Formation, an alluvial deposit consisting of weakly cemented sand. Once excavation of the access portal at the Sloat/Great Highway parking lot began, it became evident that a portion of the tunnel would be excavated through beach/dune sand. Based upon the expectations of the Geotechnical Design Summary Report (GDSR), encountering beach/

Jan 1, 1993

By Pramod C. Thakur

Floor gas emissions on wide longwall faces are common occurrences in the Northern and Central Appalachian basins. It creates unsafe working conditions on the face and results in very costly production delays. This paper discusses various methods of mitigating the floor gas emissions including hydrofracing of underlying strata, use of cross-measure boreholes and specifically completed gob wells.

Jan 1, 2005

By Andy Davis

The evolution of pit lake water quality depends on the lithology and hydrologic characteristics of the ultimate pit surface, the availability of buffering capacity in the wall rock vs. oxidizable sulfide content, the alkalinity of recharging groundwater and the evapoconcentrative characteristics of the system. This paper assesses the geochemistry of 11 existing pit lakes, ranging from the acid Red Hill and Berkeley pit lakes (pH 2.6 to 2.8) to the alkaline Yerington pit lake (pH 8.45). Predicted pit lake chemistry is similar to that in existing pits, with long-term chemistry lying on a geochemical continuum between end members that consist of influent calcium bicarbonate groundwater and naturally occurring sulfate-rich evaporate playa lakes.

Jan 1, 1997

By Chris A. Fleming, Daan Seymore

The Golden Jubilee Mine in South Africa is the first mine in the Western World to introduce resin-in­pulp technology for the recovery of gold from a cyanide-leached slurry. Located in the Eastern Transvaal region of the country, the plant processes approximately 375 metric tons• of ore per day, of which over 90 per cent is mined in an open pit adjacent to the metaflurgical plant, while the remaining 5 to 10 per cent is trucl<ed in from two small high-grade deposits, located about 10 kilometers from the plant. The gold grade in the open pit is about 1 git, while the values m the two high-grade deposits range between 5 and 15 git. At the current treatment rate, the proven reserves m the three locations will last about another 10 years. Early testwork indicated that the ore was not well suited to conventional filtration processing or to heap leaching because of its high cfay content, and that carbon-m-pulp (CIP) would probably prove to be the most viable metallurgical route. Tcstwork to establish the feasibility of CIP for this application was carried out at Mintek in 1985. This worl<, which was based on batch-leaching and carbon-loading tests, indicated that CIP was technically feasible, but that both the rate of gold loading and the gold-loading capacity of the carbon were inferior to those obtained with Witwatersrand ores. The poor adsorption characteristics of the carbon were attributed to the abnormally high concentration of natural organic compounds (humates and fulvates) in the ore. Batch tests were therefore also carried out with strong-base resins, since resins are known (1] to be far less susceptible to organic fouling than is activated carbon. The results were very promising, and pointed to fast kinetics and a high loading capacity. (Fig. 1 ). Notwithstanding these findings, it was decided to recover gold with activated carbon at Golden Jubilee Mine because the CIP process was, by then, well established in South Africa and elsewhere in the world, whereas resin-in-pulp (RIP) was unproven technology. The r>lant was commissioned in September 1986 and, for 18 months, operated in a carbon-in-leach (CIL) configuration, i.e. with a total of . six leach tanks, the last four of which contained activated carbon. As could have been predicted from the laboratory results, the performance of the CIL plant was generally poor, low gold loadings on the carbon (less than 1500 git) and high losses of soluble gold (0.2 to 0.3 p.p.m.) bemg characteristic of the operation. Consequently, it

Jan 1, 1990

By Bruce Cavender

Production managers look to innovative practices and equipment to reduce operating costs and improve efficiency. These innovations apply to both technical and social aspects of production operations and may be high-tech or low- tech in nature. They may be based on the implementation of a few large-scale "breakthrough projects or numerous small-scale activities, depending on the availability of capital funding and the company&apos;s past experience. Successful managers systematically identify innovative opportunities that capitalize on their organization&apos;s expertise. They quantify the associated benefits and risks and then manage the implementation of selected innovations to minimize cost and uncertainty. They monitor the results of the innovation after it has been implemented and adjust operating and managerial practices as necessary to maximize the innovation&apos;s benefit.

Jan 1, 1998

By Erik Westman, BEN WESTON, SETAREH GHAYCHI AFROUZ, KATHRYN DEHN

This study investigates the changes in seismic velocity of rockmass before and after three major seismic events to determine any potential identifiable precursory velocity changes associated with these events. Induced stress measurement is one of the challenging tasks in deep underground mining, with extreme impacts on the safety and stability of the mine. This study used p-wave passive seismic tomography to image the velocity redistribution within a rockmass, which can indicate induced stress level changes in the rockmass and detect the velocity changes that might precede a major seismic event or a rockburst. The ultimate goal of this research focus is to develop another tool for the deep-mining community that will help to increase safety and efficiency. For this purpose, the hypothesis of conventional mechanics, which implies induced stress at the hypocenter (as inferred by the p-wave velocity) increases until the seismic event occurs, is evaluated. It is found that the p-wave velocity did not increase at any of the three hypocenters prior to the seismic event occurring; however, the p-wave velocity did increase in the closest “zone center” for two of the three events. 

By Rick Coleman

PT Freeport Indonesia’s (PTFI) latest expansion has increased total mill throughput to 125kt/d (137,700 stpd). The most recent expansion included the installation of a semiautogenous mill (SAG) designed to treat more ore than any other single SAG mill currently operating in the world. Also included in the expansion were two large ball mills, rougher and cleaner flotation, including conventional and column cells, and a regrind circuit. All equipment is supported by a modern distributed control system. PTFI’s operations are located in the Ertsberg mining district of Irian Jaya’s Jayawijaya Mountains, the eastern-most province of the republic of Indonesia on the Island of New Guinea. PTFI, the operator, is owned by Freeport McMoRan Copper and Gold (81.3%), the government of Indonesia (9.4%) and private Indonesian investors (9.3%).

Jan 1, 1996

By H. Reginald Hardy, Xiaoqing Sun

Rheological models are widely accepted as a means of describing the mechanical behavior of geologic materials. It has been found, however, that rheological models developed for a specific stress level on the basis of linear visco-elasticity generally are not satisfactory at other stress levels. It has been suggested that the parameters of such models should be functions of stress level (Hardy, 1965; Kim, 1971). In this paper, continuous functions of stress have been utilized to obtain the required variation of Burgers model parameters with stress level. The model developed using these functions provides a constitutive relation which reflects the real time-dependent behavior of rock materials. The new model is capable of predicting the creep behavior over a wide range of stress levels and also predicts mechanical behavior under different loading condition (e.g. constant stress rate). It is also interesting to note that the mechanical behavior of individual elements in the model appear to reflect the different stages of brittle fracture in rocks (Bieniawski, 1967), namely; crack closure, elastic deformation, stable fracture propagation and unstable fracture propagation.

Jan 1, 1986

By Wieda Azani, Alexander Tarigan, Willem de Beer

In block caving, the rates and sequencing of undercut production blasting, drawbell blasting, and mucking are the key levers for attempting to manage cave performance. Cave performance encompasses a range of factors, which include growth, shape and the effect of the cave on the abutments, excavations, geological structures and lithology. We compare production data in several panels in the Grasberg DMLZ and GBC block caves with the seismic response in work areas, around geological structures, and in geotechnical domains. These comparisons enable evidence-based conceptualising of the effect of production rates and mining layouts. By also considering the correlation of seismic release rates in different parts of the rock mass, the wider influence of a cave can be gauged through considering possible stress and / or deformation transfer. This concept is not novel, but it is rarely implemented in a routine fashion, principally because production data rarely are easily available. Previously, it has also been used to retrospectively compare seismic hazard between different mines. This paper discusses practical, day-to-day tools to manage seismic response to mining. Therefore, the paper presents a methodology for presenting seismic release and production rates on integrated plots at any time to facilitate quick identification of correlated spatial regions. This methodology explores the production data collection and geolocation at Grasberg, which will be described in some detail.

Apr 26, 2022

By M. J. Wilhelm

Bromine is the intermediate member of the halogen family of elements between iodine, a solid, and chlorine, a gas. The name is derived from the Greek bromos, meaning stench. Bromine is the only nonmetallic element that is liquid at room temperatures, with a melting point of -7.2°C and a boiling point of 58.78°C. Reddish brown in color, it dissolves easily in water to yield a red solution. Bromine volatilizes at ordinary temperatures to a red vapor that is very irritating to the eyes, nose, and throat. Density of the liquid is 3.12, and gas weighs 7.59 gpl in standard conditions. Because the element is highly active, it exists in nature only as bromide compounds. Bromine was discovered by Antoine Jerome Balard in seawater bitterns in 1825 and began to find commercial applications shortly thereafter in photography, medicine, and dyes. The first commercial production of bromine was in 1846 in Freeport, PA, followed by production in Germany in 1865. OCCURRENCE Bromine is widely distributed in nature, and compounds occur in solution in natural brines, in seawater, saline lakes, oil and gas well brines, and in evaporite chloride minerals. The concentration of bromine salts ranges from 60 to 65 ppm in seawater to several thousand ppm in oil well brines and saline lakes. The distribution of bromine in marine evaporite minerals and in the solutions from which they crystallized was determined many years ago by H.E. Boeke (1908). Theoretical aspects regarding the geochemistry of bromine have been published in numerous papers (Raup and Mite, 1969). Bromine occurs in solid solution in carnallite and sylvite associated in potash deposits, in halite in salt beds, salt in oil shales, and in trona deposits. Its presence is useful as a guide in geochemical exploration. The analysis of small amounts of bromides in the presence of large amounts of chlorides is discussed by W. Schwerdtner (1963). Manganese, iron, and iodine may interfere with the determination. Other analytical methods are discussed at length in literature (Stenger and Atchison, 1964).

Jan 1, 1994

By Thomas F. Torries

It does not take sophisticated economic analysis to determine the current status of nickel production and demand (Figure 1). One only needs a quick glance at the balance sheets of the major nickel producers to learn that prices are down and profits are supressed to the point where they are major losses. Operations have been closed, and those remaining in production have reduced output. What Is now of interest Is, when will the nickel market improve and to what degree? The purpose of this paper is to attempt to answer these questions. This will be done by the normal method of projecting nickel demand, chosing a production scenario, and analyzing the results.

Jan 1, 1982

By V. F. Swanson

A mathematical model for free and hindered settling of minerals was developed. This paper describes how to apply the model in designing systems, such as fluidized bed, elutriation, mixing pumping systems, involving solids and fluids.

Jan 1, 2000

By R. Vogt, H. C. Mult, F. L. Wilke

INTRODUCTION At present, the capability of production planning software based on Linear Programming (LP) is still limited to the optimization of the single LP-run. This is due to the LP-model itself which cannot consider the interdependencies between individual LP- runs. With regard to planning of selective mining this limited way of optimization frequently leads to situations, where the remaining and accessible ore blocks do no longer allow to produce ROM-ore in the qualitative composition required by the ore processing plant. However, many of the aspects taken into consideration when setting up production plans built from mutually dependent LP-runs cannot be modelled in a system of linear equations. They are thus unsuited for treatment with LP and have to be taken care of by the planning engineer without any assistance by the system. The KBS currently under development is intended to assist the planning engineer in designing a production plan under special consideration of the combination of consecutive LP-runs and blending beds. It is not necessarily intended to find the optimum solution within a given planning situation which is, anyway, hard to determine due to the multitude of influences. The objective is rather to work out a good and - from the practical point of view - feasible production plan. The new aspect with respect to mine planning is the integration of expert knowledge and experiences via the KBS into the planning process in order to support the planning engineer. The planning system is being developed in close cooperation with an iron-ore open pit mine. COMPONENTS OF THE PLANNING SYSTEM The software is being developed on a workstation under UNIX and comprises the components LP, CAD-module and the KBS. The applied multi-goal LP-algorithm is an in-house development of the Department of Mining Engineering at Technical University Berlin. It was already successfully implemented within other mine planning programmes and was only slightly adapted to the specific needs of the present system. Within individual LP- runs it finds the optimum qualitative composition of ore production in the sense of the selected optimizing criterion and under the given restrictions: i.e. it determines tonnages to be mined from blocks in order to optimally meet the requirements of the ore pro- cessing plant. A CAD-module based on the commercial SURPAC package in combination with a simulation device is used to graphically depict the block model and progress of mining. Both LP-algorithm and CAD-package are integrated in the KBS. It has been decided to use the shell NEXPERT OBJECT as it is a hybrid system which supports both rule-based and object-oriented knowledge representation. MINE-MODEL AND LP-MODEL KBS have to be tailor-made for specific planning problems. Therefore, it had to be decided which specifications of the iron-ore mine should be represented in the model. As the limited possibilities of a university institute do not allow to develop a KBS for mine planning which is ready to use in industry, it was decided to concentrate on those characteristics that can be regarded as typical for iron-ore surface mines and that seemed to be suited for treatment with knowledge-based techniques. The following chapter summarizes the most important features of the mine model. The description of the requirements to the mine&apos;s sales products is followed by an outline of the applied LP-model. Mine model • The model of the mine as it is used for planning consists of • the block model of the deposit, • the mobile equipment, • stockpiles and blending bed and • the requirements to the sales products. The deposit is described by a block model which contains data on the chemical composition, LOI, grain size and tonnages. Grain size was included as it is important for the two sales products of the mine. Furthermore, it is known whichs blocks require and which don&apos;t require blasting; this is relevant to the assignment of loading equipment to individual blocks. The blocks are devided in three categories: • ore, which will directly be taken to the blending bed; • waste, which will be put on the waste dump; and • blocks which will be either transported to the blending bed, to stockpiles or to the waste dump depending on the specific planning situation. This decision is made during planning. Neighboring blocks are combined in mining areas to which the loading equipment is individually assigned. Mobile equipment comprises shovels and wheel-loaders as well as trucks. The characteristics of the loading equipment are important for their ability to load different blocks and for the permissible degree of their re-positioning etc. The mine disposes of a blending bed for homogenization of the production, of a waste dump, and of several stockpiles with different ore qualities. The requirement to make only limited use of the stockpiles for economic reasons is included in the KBS. According to long term planning two commercial products have to be produced, which differ both in grain size and qualitative composition (TABLE 1). Their mass-proportions in the blending bed have to be within a fixed range. Not considered in long term planning is the occasional need for lump ore, which occurs at very short notice and has to be produced in a "campaign-like" manner. This requires the total re-arrangement of all plans for on- coming blending beds and would therefore be ideally suited for

Jan 1, 1996

By P. Asadollahi, M. Invernizzi

"This paper describes the innovative full-face conventional tunnel excavation technology, with its advantages in terms of savings and safety. The full-face approach has been developed throughout the experiences gained in tunnel construction. The innovative design approach is focused primarily on the deformation response of the ground acting first and foremost ahead of the face, which is analyzed, predicted and controlled by pre-confinement of the core. The advantage of this method is particularly evident in difficult grounds. This paper will present the outstanding benefits given by the adoption of the full-face approach in two projects, the “Sochi” and the “Visnove” tunnels. THEORY AND DESIGN ASPECTS OF THE FULL-FACE EXCAVATION The main challenges in tunnel and underground construction industry are gathering the design data from the ground that is being excavated and foreseeing the critical stage during construction, where the materials are in its most critical configuration. These challenges shall be addressed during excavation when the lining and the excavation disturbance have not yet reach the equilibrium. The in situ stresses in the ground are redistributed (forming an “arch-effect”) around the opening, with zones of increased stresses around the walls of the excavation (Figure 1). The distribution of the stresses can be close or far from the excavation profile, depending upon having a ground capable of withstanding the deviated stresses well or unable to withstand them, respectively. In the latter case, the ground will plasticize and deform in proportion to the volume of ground involved in the plasticization phenomenon. When the ground completely cannot withstand the stresses redistribution, it will cause the collapse of the excavation. While in the first case, the arch effect occurs naturally, in the second case, it does occur naturally only when the ground is stabilized properly. In the case of collapse, the arch-effect must be produced artificially operating on the ground prior excavation. The design should be based on the understanding of if and how the arch-effect can be mobilized during tunnel excavation and ensure that is formed by calibrating excavation and stabilization operations appropriately. The arch-effect is function of the medium that is being excavated, the action taken to excavate and the reaction expected following the excavation."

Jan 1, 2018

By Richard L. Sanford

The generalized rail haulage simulator described in this paper is an outgrowth of the need to expand a previously developed single level simulator to permit analysis of production problems where intermediate car storage is used. Many of the ideas of the former single level simulator, which is an integral part of an Underground Generalized Materials Handling Simulator (UGMHS), have been used in model development. In addition, experience gained in applying the earlier model to a variety of operating conditions has been heavily relied on. The generalized rail haulage simulation model can operate as an independent system and, as such, can be used to analyze rail haulage systems using production distributions as data input. In addition, this model is designed to replace the present rail haulage sub-assembly in the UGMHS model and the linking procedure has been integrated into the model. The flow of coal from production sections in UGMHS, for example, fill the mine cars and a condition of no empty cars at a loading station will shut down in by production systems.

Jan 1, 1974

By E. J. Owen, A. Appah, I. C. Sanchez, K. T. Stafford, N. Hurtig, R. Otoo, N. A. Iverson, S. A. Moses, V. T. McLemore

New Mexico lies at the eastern edge of one of the world’s great metal-bearing provinces hosting numerous Laramide and Paleogene mineral deposits. Southwestern New Mexico contains Laramide porphyry Cu (±Mo, Au) and Paleogene Mo-W deposits. Porphyry deposits are generally large, low-grade deposits containing Cu, Fe, Mo, Au sulfides (and other metal sulfides) associated with porphyritic intrusions and exhibit characteristic alteration styles. Porphyry deposits can also be spatially and temporally associated with skarn deposits and polymetallic veins. All of these deposits have the potential to host various critical minerals, including Cu, Zn, Bi, Co, Ni, rare earth elements (REE), Te, and W. Critical minerals may be found as substitutions within ore minerals or as separate mineral phases. These deposits are constrained using 40Ar/39Ar dating into three ore-producing magmatic pulses: 1) ~78–71 Ma Laramide pulse, 2) ~59–50 Ma, Laramide pulse, and 3) ~40–30 Ma Paleogene pulse. New and historic whole-rock geochemical data have highlighted areas with critical minerals potential that require further study.

Feb 1, 2025