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By J. A. Hrabik

The feasibility of mining deep phosphate deposits by a borehole mining system was compared with mining by proven conventional techniques. An economic comparison of the borehole mining system with conventional dragline and bucket wheel excavator mining systems was completed at various mining depths and production rates. Hypothetical phosphate deposits, with various overburden thicknesses and reserve tonnages, were defined. Geologic conditions necessary for the application of the borehole system were identified. Discounted cash flow analyses based on derived capital and operating costs were used to generate rates of return and product prices. Borehole mining was found to be more economical where overburden thickness was 46 m (150 ft) or greater. However, at 15- and 30-m (50- and 100-ft) thicknesses, conventional surface mining was more economical. Overburden thickness has a great effect on the economic feasibility of the conventional mining systems but less effect on the economics of borehole mining. Economies of scale are only realized in conventional mining, since larger equipment is used to achieve greater production, whereas increased production from borehole mining is achieved using additional equipment units. A comparison of the environmental effects of borehole and conventional surface mining systems showed that borehole mining is environmentally more desirable.

Jan 1, 1987

By Jeong-Heum Kim, Jan M. Mutmansky, Y. J. Wang

The simulation of randomness in a system of components is important in certain types of systems analyses. This paper presents procedures for generating ventilation networks that are random in many of their characteristics and which can be used to study the performance characteristics of various mine ventilation network analysis procedures without introducing undue bias as a result of the nature of the network. Among the parameters of a network that affect the efficiency of a network analysis procedure are: (1) the interconnection pattern of airways, (2) the distribution of resistances in the network, (3) the number and location of fans, (4) the fan characteristic curve, (5) the size of the network (number of branches), and (6) the density of the network (number of nodes compared with the number of branches). In the procedures proposed here, a single fan with a fixed characteristic is used to simplify the problem and eliminate the fan as a source of variation. The resistances of the airways, the pattern of interconnection of the airways, and the fan location are randomly chosen in an attempt to eliminate the bias in the performance characteristics of the network analysis methods caused by these parameters. A method of generating biconnected networks while keeping the "randomness" of these other parameters is suggested. At the same time, the size and the density of networks are controlled to investigate their impacts on the performances of the network analysis procedures. The combination of these two variables has been termed the "level of complexity" of the network in this paper. Finally, a summary and conclusions section outlines some characteristics of the networks generated, using the random generation procedures outlined in the paper.

Jan 1, 1991

By Erik A. Munroe, Nelia W. Dunbar, Virginia T. McLemore

In New Mexico, there are at least 100,000 abandoned mine waste rock piles with widely ranging geochemical and mineralogical compositions. A geochemical and mineralogical study was implemented for five waste rock piles, some which contained sulfides, in the Hillsborn Mining District. Chemical and physical characteristics of mineral grains and their secondary mineral oxidation rinds were examined with the electron microprobe. Pyrite and chalcopyrite appear to be the most reactive to oxidizing conditions. Clays, iron oxide, iron hydroxide, iron sulfate, and primary texture rinds exist in the waste rock piles analyzed.

Jan 1, 2000

By R. E. Johnson, J. E. Dutrizac, B. R. Palmer

Silver sulphide (acanthite) and lead sulphide (galena) dissolve relatively rapidly in FeCl3 media with the formation of elemental sulphur and soluble silver and lead chlorides. Parabolic kinetics are observed, and the leaching rates are controlled by the outward diffusion of the AgCl and PbCl2 reaction products through the constantly thickening elemental sulphur layer formed on the sulphide. Hence, both leaching rates are strongly dependent on those variables which affect the solubility of AgCl or PbCl2 at the reaction interface. The rates therefore increase with increasing temperature and total chloride ion concentration, but decrease in the presence of elevated concentrations of AgCl or PbCl2. By contrast, neither sulphide is significantly attacked by ferric sulphate media, even at high Eh values. Although the reasons for the refractory behaviour of Ag2S in sulphate media remain unknown, the low rate of PbS attack is attributable to the passivating layer of PbSO4 and elemental sulphur formed on the surface of the galena.

Jan 1, 1993

By C. O. Brawner, A. Bellamy, D. S. Cavers

Pit slope designs at Nickel Plate Mine have used relatively steep interim and final wall slopes of 60 degrees overall. The rock is unusually strong and tough with most discontinuity sets being steeply dipping. An integrated program of monitoring and drainage has been used. Stopes of large extent which are generally unsupported occur on the property. For the most part, no deterioration of the stability of the stopes has occurred over the last 30 or more years. Mining methods through these areas have used a combination of fill s placed via VCR drop raises and crater blasting of the backs. One of the major challenges in mining through the stope areas is to maintain slope stability conditions and to reduce dilution of the higher value ore zones occurring immediately around the stope areas. The paper discusses geology, slope stability and mining methods at Nickel Plate Mine.

Jan 1, 1988

By J. A. Dlas Lima

Alunorte is a metallurgical-grade alumina refinery located in northern Brazil. This plant which was designed to produce 1.1 million mtpy of calcined alumina, started operation in July 1995. A process information system was installed before refinery start-up. It has been a main factor in process improvements, which resulted in an increase in production from 1.1 to 1.5 million mtpy. This system has been particularly useful for analyzing data and allowing retrieval of data by process engineers. This paper describes how a quality monitoring system to evaluate all aspects and stages of production, as well as alumina silo level and blending percentage, was developed. This system was designed to give support to ISO 9002 certification, which happened in December 1998. The quality monitoring system was developed using Microsoft Excel 7.0 and makes extensive use of VBA macro. The primary users of the system are shift foremen, managers and engineers, who use it to track the process and avoid variations in alumina quality.

Jan 1, 2000

By Chris Mills

El papel de la separacion gravimétrica en la industria minera es brevemente considerado en perspectiva. Las pruebas e intentos de laboratorio y mineralógicas para el diseñio de los procesos gravimetricos son examinados poniendo especial énfasis en la selección de la tecnologia del proceso. Es tratado y comentado el material disponible en equipos para pequeña escala y trabajo de pruebas-piloto, particularmente en relación a la escalacion y a la adquisición de datos precisos y fiables. El transporte del comportamiento de los datos desde la planta piloto a la planta a escala es igualmente explicado. Son resefiados todos los tipos de equipos a escala total existentes para la separacion gravimétrica, poniendo de relieve las unidades de alta capacidad. Es considerada la disposicion de la planta y la seleccion de 1os equipos auxiliares.

Jan 1, 1982

By R. P. Benson, D. H. MacDonald, D. R. McCreath

1 - INTRODUCTION The Canadian Shield is well known as being among the older exposed areas of the earth's surface. Except for local zones, its extent from the Arctic to central North America is characterized by strong and durable crystalline rocks. It is generally regarded as highly competent for tunnelling and underground excavation and, as a result, many openings are excavated in it with minimal temporary support. If hydraulic efficiency is not a factor, tunnels do not usually require continuous concrete linings. A high percentage of the crystalline rocks of the Shield are of metamorphic origin and as such one of the dominant characteristics is their foliation. Zones of sheared or faulted rock are common in the Canadian Shield, particularly in association with foliation. These zones may be created during the late stages of the metamorphic process, leaving shear zones as an integral feature of foliated rock. As foliation is a preferred direction of weakness, deformation and rupture during subsequent tectonism may also create parallel shear zones. These "foliation shear zones", as described by Deere (1973), are an adverse feature of the otherwise durable rocks of the Canadian Shield. The zones may range from faults of major proportions to seams only a fraction of an inch thick. If fault gouge or alteration products exist in the zone the strength of the rock mass may be great1y reduced. As foliation is usually continuous, large unstable wedges of rock may be created if the opening is subparallel to the foliation. The effect on the construction of underground openings in terms of excavations, support and scheduling can be significant.

Jan 1, 1974

By Ted H. Eyde

The Bowie chabazite deposit has yielded the most mined tonnage of any natural zeolite deposit in the United States. Since 1962 the deposit has yielded about 12,000 tons of crude chabazite, with an estimated market value of S30 million when sold as an activated molecular -sieve product. Between 1,000 and 1,500 tons of high-purity crude lump chabazite is now produced annually by stripping and selectively mining the lower, massive, half-foot-thick, "high-grade" bed. All of the chabazite is still shipped out of State for grinding prior to extrusion and activation. Zeolite minerals were discovered at the Bowie deposit in 1875, when Oscar Lowe identified a hydrous silicate related to chabazite or stilbite from a tuff bed that cropped out in the San Simon Valley. It was not until 1959, however, that chabzite, erionite, and clinoptilolite were positively identified as the principal constituents of an altered vitric-tuff horizon that crops out in the area originally described by Lowe. Shortly after the rediscovery of zeolite minerals in the San Simon Valley, several of the major producers of synthetic zeolites acquired land positions covering the outcrops, including projected extensions, and began exploration drilling. By 1980 all of the known chabazite reserves had been acquired by five companies and two individuals. The more than 3,000 holes drilled to explore the deposit and the excellent exposures provided by the strip-mined areas indicate that the chabazite-bearing horizon (known as the marker tuff) is confined to a flat-lying lacustrine section known to the operators as the Green Lake Beds. The deposition of the parent airborne vitric ash and subsequent zeolitic alteration was controlled by many factors, including the lake-bottom topography, depth and cation content of the saline-alkaline lake water, and proximity to post-depositional erosion surfaces. Zeolitic alteration was complete when an extensive system of younger paleochannels deeply eroded the Green Lake Beds. This left only a few erosional remnants of the marker tuff and the lower "high-grade-bed" that constitute the present deposit. Both the channel gravels and the Green Lake Beds are overlain by a section of halite-bearing brown mud-stones, known as the Brown Lake Beds. The bowie chabazite deposit can be used as a model to guide the exploration and development of other zeolite deposits that formed in saline-alkaline lacustrine environments.

Jan 1, 1987

By A. W. Easton

INTRODUCTION This presentation will address changing trade patterns in lead and zinc from the mid 1980's to the early 1990's. Lead and zinc deposits are developed where they are found in many parts of the world. As many are not in major consuming areas, there is significant international trade in both lead and zinc concentrates and in refined metal. Forecasts of mine production have been analyzed, primary and secondary refining capacity and future consumption levels have been estimated, to arrive at the changes in trade patterns expected during the next half decade. This paper will first address concentrate and metal trade patterns for lead, then for zinc, and finally some remarks will be made on captive mine/smelter agreements, on regional trade agreements, and on barriers to trade. I would like to note that. there is only a small international trade in semi-fabricated products such as zinc die-cast alloy, zinc oxide, lead oxide or rolled lead and zinc. Most of the world's zinc and lead trade is in concentrates or refined metal. LEAD TRADE PATTERNS Lead Concentrates Six countries are exporters of lead concentrates. Three countries are in the Americas - Canada, Mexico and Peru, with two in Africa - Morocco and South Africa (including Namibia), and Australia. Due to the limited growth in lead consumption and consequent minimum investment in new production facilities expected, mine and metal production levels and future consumption levels are not forecast to change much between now and 1990. Accordingly, the tonnage of lead concentrates exported will remain essentially unchanged from these six countries. In total they have exports of 480,000 metric tonnes (metal content)* and by 1990 this figure is forecast to rise only slightly with the only increase taking place in Mexico. The concentrates are exported mainly to Western Europe & Japan. Apart from these six main lead concentrate exporting nations, a significant change is expected in the United States. In the mid * All concentrate trade figures are based on metal content

Jan 1, 1986

A linear programming model with integer sequencing variables is developed to schedule limestone production for a quarry in Central Japan. The model is used to optimize raw material production from the quarry supplying limestone to cement, quick lime and aggregate plants. Typically, the mining in the quarry takes place in four to six different areas each area having 3 or 4 mining increments. Each mining increment contains different quality of limestone. The limestone production from the quarry is transported to the plants byway of 3 ore passes. Each plant requires a given quantity of limestone per period meeting certain quality constraints. This paper will describe development of the scheduling optimization model and how it is used to schedule production by period within the quarry to meet the capacity and blending requirements of the plants.

Jan 1, 2003

By Ralph H. Knode, Stephen P. Collings

INTRODUCTION The Crow Butte uranium deposit is located in northwest Nebraska near the town of Crawford (Figure 1). The deposit was discovered during the fall of 1980 by Wyoming Fuel Company, operator of the Crow Butte Joint Venture. The Crow Butte Joint Venture is owned 50 percent by Wyoming Fuel Company, a subsidiary of KN Energy, Inc.; formerly Kansas-Nebraska Natural Gas Company, Inc., 40 percent by Ferret Exploration Company, Inc., and 10 percent by First Exploration Company. A preliminary announcement made in January 1981 indicated a "probable potential" reserve in excess of 25,000, 000 pounds U303. Drilling during 1981 and 1982 confirmed these reserves and indicated the presence of more than 30,000,000 pounds U308 having an average grade in excess of 0.25 percent U308. Wyoming Fuel Company was initially attracted to the area in 1978 by favorable regional geology for sandstone uranium deposits and weak radioactivity noted in regional oil and gas holes. Exploration drilling began in 1979 following the formation of the Crow 3utte Joint Venture. Drilling has continued up to the present, at which time the Joint Venture is ready to proceed with a pilot scale solution mine. Environmental baseline data have been acquired and the permit applications for the pilot scale mine have been submitted to the Nuclear Regulatory Commission and to the applicable state agencies in Nebraska.

Jan 1, 1984

By Fathi Habashi

A LARGE number of metals are found in nature, in rich deposits, in the form of sulfides as shown in Table 4.1. Treatment of sulfide ores is done mostly by pyrometallurgical operations; it is only recently that hydrometallurgical processing started to compete with pyrometallurgical methods.

Jan 1, 1970

By Klaus Böde

Within the national and international strategy of the German based construction company HOCHTIEF, the majority of its business units is equipped with the comprehensive software package ARISTOTELES. This software is a powerful business information system for all accounting and controlling related processes in medium-sized and large construction and other related companies. Due to the complexity of the software, time constraints, and limited financial resources an implementation of this software package requires thorough project management. In this paper the relevant elements of project management are outlined based on practical experiences gained during this international IT - implementation project. Special emphasis is directed to the identification and management of potential risks. In this case particular acknowledgement was given to the multinational nature of the project and modernization of the business. This includes thorough reorganization of the company, significant changes of job requirements, and substantial trainings for its employees. At the same time key success factors like knowledge transfer, adoption of Czech legal requirements, commitment of management, networked thinking, and integrated project planning come into play. The costs for implementation had to be carefully evaluated because the software was implemented in a country with a considerably low cost I price level. All these impacts to the business had to be managed within the scope of transformation of business and political environment from socialist to market driven economy.

Jan 1, 2002

By S. K. Mukherjee, A. W. Laurito, M. M. Singh, N. I. Jayaraman

This paper describes the application of foam to control respirable dust in a double-drum longwall mining section. The feasibility of injecting an adequate quantity of foam through the shearer drum was initially established in the laboratory. Thereafter, underground testing of the foam system to determine its effectiveness on an active operating longwall was conducted in a mine in West Virginia. The foam system proved superior to the water spray system. The details of the laboratory and field investigations, the results obtained, and the degree of acceptance of this system by the mining company are discussed in this paper.

Jan 1, 1987

By Tugba Kami?oglu

Hydromagnesite (Mg5(CO3).(OH)2.4H20), one of the sedimentary deposits in Salda Lake Basin, is developed under the control of active tectonics regime. Since the occurrence and deposition mechanism of hydromagnesite are unstable under atmospheric conditions, in order to evaluate the precipitation process, systematic host rock, lake water (surface, 20m, 40m, 60m) and hydromagnesite sampling were carried out. Macro, micro, XRD and chemical investigations were done in detail. Not only the results and formation and crystallization mechanism but also hydromagnesite's St values were evaluated. Main resources could be ultramaficmafic surrounding rocks for hydromagnesite formations. However, hydromagnesite development is considered in different phases, because it has showed various characteristics in Kayadibi and Köpekcayin areas. In Kayadibi area Huntide-Dolomite-Aragonite-Hydromagnesite paragenesis has been realized. Hydromagnesite has also formed in Köpekcayiri area, large amount of hyrdomagnesite occurrences and levels various are noticeable. Actual position of hydromagresite levels exhibits tectonic influences in and around the lake. Therefore, the levels seems to exhibit secondary formation properties. In addition, the formations are being still maintained sedimentation as products of a peripheral deposition phases. Resolving and redifferentiation sedimentation processes probably improve in periods of lake water chemistry especially Ca/Mg proportional changes, and also SI variations indicate the mentioned precipitation mechanism. Similarly, side and into the lake hydromagnesite is stored different levels and ultramafics-mafics rocks fallow indicated stages. It is postulated that hydromagnesite formation, which is existed by result of determined developments and multiphase sedimentation, could be originated from probable crack zones on the lake bottom.

Jan 1, 2005

By H. Para, A. Aguirre, G. Artadi

Mining is a very important economical activity in Peru which has been recently developed without considering environmental aspects. Here, we show an experience at the Milpo mine, situated 4,200 meters above sea level; a mining company that has the value of being one of few from the last decade that is engaged in consolidating a model of environmental protection. The model includes aspects of contamination prevention and control, with bioindicators such as pasture cultivation, vegetables, forests, and hydrobiological species breeding. Socially, through means of development programs in natural areas, forestation and support to rural agriculture, together with environmental education, it is being demonstrated that it is possible to ensure tangible results in environmental conservation and the well-being of the populations around the mine.

Jan 1, 1998

By G. Yang, M. J. McPherson, P. Mousset-Jones, G. Danko, F. Calizaya

In the last 20 years, studies on controlled flow recirculation in various countries have been carried out in both coal and metal mines. These studies have shown that in addition to economic gains, partial flow recirculation can be used to provide mine workings distant from surface access points with the required volumes of air. These studies have also shown that the operation of fans and regulators, used in a recirculation system, will induce transients in gas flow and gas concentration. Various models have been developed to explain the problem. However, most have failed to incorporate important factors such as diffusion and dispersion in the modeling process. This study examines the theoretical background of gas emission transients from caved areas in coal mines, represents the problem by a "tank-airway" network model, and provides a possible solution. The study also presents the results gained from a laboratory model constructed to evaluate the major factors affecting the shape and duration of gas flow and gas concentration transients in an airflow recirculation system. In this model, the gas injection system was rearranged to simulate the variations in gas emission rates due to changes in air pressure. Within this model, a set of booster fans and regulators were used to generate the changes in air pressure within the model. Finally, the study presents an algorithm and a computer program GASTRAN, developed to analyze the gas concentration transients and calculate the pollutant transport levels in a complex ventilation network. The application of the program is illustrated by means of an example problem.

Jan 1, 1991

By M. F. Dibble

Borehole mining, as a viable concept for recovering deep sedimentary mineral resources, historically has been long on promise but short on results. Application of the technology seems best suited for recovery of Miocene phosphate resources on the East Coast of the US. These deposits are potentially enormous in scope and underlie sections of the coastal plain and the near offshore continental shelf. The landside portion of these deposits is generally too deep to mine using conventional open pit methods. Recovery of these minerals requires development of alternative mining systems. A significant proportion of the offshore resources appear to occur at depths below the practical limits of cutter suction dredges and may even exceed the limits of bucket ladder dredges. In most cases, these deposits are covered by overburden that must he removed and redeposited before the mineral section can be mined. The depth, thickness, composition of overburden and environmental sensitivity of a particular location would greatly impact mining system selection. It is probable that dredging would not be an environmentally acceptable mining method in many of the areas underlain by this phosphate rock. In cases such as these, new processes such as borehole mining must be evolved or the resource will remain undeveloped. A borehole mining test program, using an existing prototype borehole system, successfully extracted Miocene phosphate in northeast Florida in 1984-1985. The top of the main mineral zone was 80 m (261 ft) below the surface. Based on the results of this test program. plus subsequent laboratory testing and engineering studies, a new prototype borehole mining system was designed in 1986. This design incorporated several innovations of offering potentially higher productivity and lower power consumption than was achieved with the previous test unit. Economic restraints at that tine prevented the actual construction and testing of this new design.

Jan 1, 1992

By George A. Desborough, David L. Fey, Stanley E. Church

About 100 mine-waste dumps from past metal exploration and mining in Colorado and Montana were sampled using surficial-sampling methods for laboratory studies of the minus-2-mm fraction. In the laboratory, the composite samples were split into l00g samples that were leached to assess their acid-generation potential and associated release of potentially toxic metals that may degrade water quality in the headwaters of the Animas River watershed in Colorado and the Boulder River watershed in Montana. Two leach methods were studied: a passive leach using de-ionized water, and a more aggressive leach following the EPA-1312 method. The resulting pH values of the leachates using both methods are comparable. The concentrations of sulfate and several, but not all, dissolved or water-soluble metals are higher in the EPA-1312 leachates than in the passive leachates; however, the overall trends of the data are very similar. The passive leach method is less labor intensive and may be more representative of the natural weathering process occurring on the mine-waste dumps, simulating the natural precipitation and snowmelt. Three chemical characteristics of mine wastes studied here provide a relative ranking of mine-waste dumps for the purpose of determining priority for removal or remediation. These characteristics are: net acid production (NAP), sum of dissolved toxic metals (?As+Cd+Cu+Pb+Zn), and dissolved iron in leachates. Ranking can be done evaluating plots of NAP versus the sum of dissolved toxic metals, and NAP versus dissolved iron. These two plots serve as a basis for relative ranking of polymetallic-vein and acid-sulfate mine wastes studied. This ranking scheme may apply to mine wastes from production of other deposit types in other watersheds.

Jan 1, 2000