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By S. L. McGill, P. B. Comba

Many gold producing states are requiring rinsing of spent heaps to render the leached ore compatible with the environment and are placing reatrictiona on effluent pH, cyanide, and metals concentrations. Parameters which may affect efficient rinsing of heaps have been investigated by the U.S. Bureau of Mines in laboratory column studies. Rinse profiles for cyanide, metals, and pH as a function of the volume of water passed through the spent ore are presented. Fresh water rinsing of spent ore in columns showed that rinsing of cyanide was not affected by the rinse solution application rate. Interrupted rinsing with a rest period between applications reduced the volume of water required to meet effluent cyanide concentrations. Chemical oxidation of the effluent with recycle of the rinse solutions reduced effluent cyanide concentrations and the volume of waste solution generated. Water rinsing was not successful in reducing the alkalinity of the cement agglomerated ore. A dilute acid solution had to be applied after cyanide removal to reduce effluent pH levels to specified limits.

Jan 1, 1991

By R. V. Johnson

The review of mineral activities in Minnesota arrived too late to appear in the May issue. Minnesota continued to lead the nation in iron ore production in 1989 with more than 70% of the market. At no time in the past 50 years has Minnesota's iron ore market share fallen below 50%. 1989 production was provided by six iron ore pellet operations and one high-grade iron ore mine. Most American steel companies are represented in these operations through whole or partial ownerships in Minntac (USS), Minorca (Inland), Eveleth Mines (Armco and Rouge), Hibbing Taconite (Bethlehem), and LTV Steel and National Steel Pellet. A seventh iron ore pellet producer started up in 1989 when Cyprus Minerals acquired the assets of bankrupt Reserve Mining Co. This operation, with first production scheduled for 1990, will be the only non-steel company captive operation in Minnesota. Encouraging minerals development In an attempt to stimulate further and additional mineral development in Minnesota, the state's legislature established a Minerals Coordinating Committee (MCC). This committee is comprised of the Department of Natural Resources-Division of Minerals, the Minnesota Geological Survey, the Natural Resources Research Institute, and the Mineral Resources Research Center. The Committee has sponsored and coordinated various projects. Among these MCC-sponsored projects are glacial drift geochemistry with an emphasis on gold and indicator minerals, accelerated geologic mapping, continued aeromagnetic surveying of Minnesota, greenstone geochemistry, structure and stratigraphy of the Duluth complex, and drill core and exploration data acquisition from past exploration programs. Regarding drill core, the Division of Natural Resources completed construction of its third core library building in Hibbing. These data and core are available for public examination.

Jan 1, 1990

By C. N. Bensley, S. K. Nicol

The major developments in fine coal processing in Australia are reviewed. Emphasis is placed on the approaches taken by various Australian coal producers to improve the recovery of the coarse size fractions (minus 0.5 plus 0.25mm) and upgrade the selectivity of flotation at ultrafine sizes (minus 0.075mm). The effects on fine coal preparation of flotation circuit changes, the influence of physical and chemical variables on coarse coal flotation and the impact of spiral concentrators and column flotation, are discussed. Reference is also made to the development of oil agglomeration technology for the treatment of fine coal refuse and some of the factors which have led to its current demise.

Jan 1, 1988

By Gary W. Hausler

Bergbau AG Niederrhein, a subsidiary of Ruhrkohle AG; Essen, Germany, is working coal mines on both sides of the Rhine River. The Prosper Mine in the City of Bottrop has a production of about 13,000 tons per day and has been in operation since the turn of the century. Mining has moved to the north as coal deposits south of Bottrop are exhausted. To facilitate ventilation, material handling, and transportation new shafts are being constructed in the northern coal fields. The Prosper 10 shaft is being sunk to develop the Prosper - Haniel coal field which has reserves of 280 million tons. In October, 1976 Bergbau AG Niederrhein awarded the shaft sinking contract for the 1047 m deep, 8 m inside diameter Prosper 10 shaft to Gewerkschaft Walter; Essen, Germany. Construction costs will amount to about 40 million DM with construction completion scheduled for 1981. GEOLOGY The shaft, located near the town of Kirchhellen north Bottrop, is being sunk in the Grafenwalder Horst between two faults on the south west flank of the Kirchheller Anticline. 270 m of upper cretaceus sands and marls overlay sandstone bedrock at the shaft location. The upper 124 m of this section contain highly saturated sands interspersed with marl. In order to successfully sink the shaft through this section, ground stabilization by freezing was used.

Jan 1, 1979

By Michel L. Van Sint Jan, Gabriel Fernandez-Delgado, Edward J. Cording, James W. Mahar

INTRODUCTION Shotcrete behavior observed in subway tunnel construction in the U. S. has been primarily in blocky or blocky and seamy rock in which rock loads develop from the self weight of individual rock blocks that tend to loosen from the wall and roof of the opening. Such conditions can be classed as loosening ground, in contrast to squeezing ground in which high pressures are generated on the tunnel lining with time as the ground creeps under the natural ground stresses. In the philosophy often associated with the New Austrian Tunneling method, emphasis is placed on the use of shotcrete and other support elements in squeezing, highly stressed ground, in which the support system is designed to allow controlled movements so that high lining stresses do not develop. In contrast to these conditions, the concern in loosening ground is to provide support soon enough to minimize loosen-

Jan 1, 1979

By Joao Felipe Costa, Jair Carlos Koppe, Alexandre Grigorieff

Discrepancies in raw materials properties informed by both producer or consumer is a common problem in most areas of the industry. Commercial contracts in the mineral industry normally penalises the producer, if contaminants in the ore exceed established limits. In some situations, the supplier is penalised if the quality of the ore is below a contracted amount. Differences in lab analysis are due many sources of error, such as distinct practices used in two laboratories for sampling, preparation or analysis. Rigid contracts impose to the miner the use of rigorous quality control program and in these situations sampling plays a major role. Sampling theory provides the tools to analyse errors involved in sampling, preparation and analysis. This paper proposes a methodology to check the precision and accuracy of a given sampling protocol emphasising the application of Gy's sampling theory to broken ore. A procedure to measure the error on each step of the protocol is introduced and the results compared to the fundamental error measured by Gy's theory. The results show the applicability of the method and its relevance to audit sampling procedures aiming at error minimisation. The methodology is illustrated in a case study at a major coal producer in Brazil.

Jan 1, 2002

By Peter Halbach

Cobalt-rich ferromanganese crusts are one type of the two oxidic metallic mineral resources in the deep ocean that incorporate metals supplied and transported from both land (aerosols, continental run-off) and sea sources (oxygen-minimum zone, hydrothermal alteration of the oceanic crust). The substances directly precipitate from cold seawater under more or less oxic conditions and form thin layers (2 up to 25 cm thick) on hard substrate rocks like volcanic hyaloclastites, weathered basaltic rocks and/or carbonate-fluorapatite; in the crusts many metals therefore exist in the highest state of oxidation. Deposits of the Co-rich ferromanganese crusts are found throughout the global oceans on the flanks, terraces and summits of seamounts and submerged volcanic mountain ranges and platforms, where the ocean currents have kept the seafloor more or less free of sediment for millions of years. The process of hydrogenetic precipitation is basically an inorganic colloidal-chemical and surface-chemical mechanism. Elements in seawater may occur as dissolved hydrated ions or as inorganic as well as organic complexes which in general have either a positive or a negative surface charge depending on the pH of the respective aqueous environment. Those complexes may form hydrated colloids that interact with each other and with other dissolved hydrous metal ions. Hydrated cations such as Co, Ni, Zn, Sn are, for example, attracted by the negatively charged surfaces of colloidal hydrous Mn-oxide particles, whereas hydrated anions (e.g. oxyanions) and elements forming larger complexes with low-charge densities (e.g. U, As, Th, Hf, REE) are attracted by the slightly positively charged hydrous Fe oxihydroxide particles.

Jan 1, 2008

By John Jonkman

Two major changes occured during the last 5 years in the applications of computers. First, the cost of computer equipment decreased drastically in an era of high inflation. Second, technological breakthroughs in hardware and software have been applied successfully so that the average person can successfully utilize the computer without having to be a computer expert himself. The mining industry has recognized that computing technology has evolved to a point where it can be applied successfully to assist in improving productivity. Since equipment downtime is one of the major reasons for lost production, the Kennecott Minerals Company has developed a comprehensive maintenance information system which now assists the maintenance department in minimizing equipment downtimes. This paper discusses the primary features and functions of this system, the state-of-the-art technology that has been applied, and the benefits that resulted from using this system. Programs to support mobile equipment maintenance scheduling, which currently are under development, are reviewed and a summary of future applications is given.

Jan 1, 1982

By Wilhelm J. Kogelmann

The quest for U.S. energy independence will result in a major increase in underground mining operations. It will necessitate the rapid excavation of development drifts, entries and slopes to exploit underground deposits of energy resources such as coal, uranium and oil shale. Most of this development work will be done in soft and medium hard rock up to an unconfined compressive strength of approximately 20, 000 psi. OBSTACLES TO RAPID TUNNEL EXCAVATION Labor In the U. S. coal mining industry, the underground productivity in tons per man-day declined from 15. 61 in 1969 to 11. 00 in 1973 which is a startling 30% decline. While productivity declines, the cost of labor and supplies continues to rise. Ralph E. Bailey of Consolidation Coal Company recently stated four reasons for the decline of productivity: A shortage of experienced miners, enactment of the Federal Coal Mine Health and Safety Act effective April 1970, major changes in union work rules in 1968, and a deterioration in the attitude of the work force (1). Because there is already a great shortage of skilled miners, the situation will get worse when large new mines for oil shale, coal and uranium open in sparsely populated areas in the Western United States. Only the large scale use of easy to operate tunneling machines can increase productivity and lower the cost of excavation.

Jan 1, 1974

By D. Armour, E. R. Bauer, D. R. Zuchelli, T. M. Durr, E. R. Reeves

A team of noise specialists from the National Institute for Occupational Safety and Health (NIOSH), Mine Safety and Health Administration (MSHA), and Joy Manufacturing attempted to evaluate an engineering noise control on a Joy longwall stageloader. The team developed and executed a test plan to evaluate the noise attenuation of the engineering control in an underground coal-mining environment. An evaluation of the long-term noise effects and durability of the engineering control were also a focus of the research effort. Pre- and postcontrol measurements consisting of a combination of worker dosimetry and task observations, tape recordings, and sound level measurements were used to evaluate the engineering control. A description of the engineering noise control, pre- and post-control sound level measurements, and an evaluation of control success is presented. In the end, no evaluation was possible due to mining practices, miner task variations, and inconclusive data.

Jan 1, 2005

By Frank E. Dalton, Bart T. Lynam, Forrest C. Neil

The Tunnel and Reservoir Plan (TARP) is the largest tunneling program in the history of the metropolitan Chicago area (Figure 1). Between September 1976 and September 1977, rock tunnel contracts having an estimated cost of approximately $420 million will be advertised. During the past six months, the Metropolitan Sanitary District of Greater Chicago (MSDGC) has awarded contracts for 16.5 miles of rock tunnels in diam of from 9 ft to 30 ft having a total bid price of $120,261,750. RECENT CONTRACT AWARDS Addison-Wilmette Tunnel $63,140,480 Upper Des Plaines #20 Tunnel 35,749,664 Upper Des Plaines #21 Tunnel 21,371,607 Addison-Wilmette Tunnel The first contract was advertised in September 1975. This contract, described as the Addison-Wilmette Tunnel, runs from Wilmette Harbor at Lake Michigan under the North Shore Channel to Addison Street in the City of Chicago, a distance of 10 miles. The contract calls for constructing approximately 27,750 linear ft of 30 ft ID and 24,020 linear ft of 22 ft ID unlined rock tunnels, excavation of two construction shafts, and the excavation of 32 drop shafts of various diam. Two hundred ninety-three companies were notified of this contract being advertised, 70 companies took out contract specifications and 3 companies ultimately submitted bids. The contract was awarded to a joint venture of:

Jan 1, 1976

By Owen E. Owens

INTRODUCTION This paper deals with the main components in exploring for and developing a gold ore deposit. It addresses geology, exploration drilling, ore reserves, and evaluation criteria in an integrated manner to present an overall picture. Gold forms such a small component of a gold ore body, that particular care should be taken in dealing with the data from a developing deposit. The paper lists the main gold ore deposit types and their character. Their differences, as well as differences to other types of ore deposits, are important to understanding exploration approaches, and problems of ore reserve definition. Gold exploration has enjoyed a great boom in recent years. Many new ore deposits have been developed but experience shows that definition of gold is not a simple straight forward process and this outline attempts to point out some of the important aspects of ore reserve definition including some pitfalls. GOLD DEPOSIT TYPES The Witwatersrand deposits in South Africa produce about 50% of the world's gold. The gold occurs as fine grains in thin beds within gently dipping quartz pebble fan conglomerates usually with associated pyrite grains. It is characterized by rather uniform distribution of gold along thin layers within the conglomerate.

Jan 1, 1988

By S. Subbarayan, S. Chander, M. S. Klima

A laboratory study was conducted to investigate the potential for recovering anthracite from coal preparation-plant tailings. The study included washability analyses, cyclone simulations and froth flotation testing Samples were collected from either the tailings streams or the slurry ponds of five anthracite-cleaning plants. From each sample, a washability analysis was conducted on the 28x100 and 100x200-mesh fractions. Using the above data, along with published partition data, simulations were performed with various cyclone-staging arrangements for both water-only and dense-medium cyclones treating the 28x200-mesh fractions. Separate froth -flotation tests were conducted on the 28x100- and 100x200-mesh fractions from three of the plant samples. The washability, simulation and flotation results are presented as grade-yield curves.

Jan 1, 1996

By H. Zhu, A. G. Journel

Qualitative and interpretive information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging, and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system provides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data. A case study using a large reference database is presented; the indicator conditioned estimates have a smaller conditional bias and a smaller error variance than the ordinary kriging estimates. The results also showed that the indicator conditioned estimator is more efficient for selection in mining.

Jan 1, 1990

By Brent K. Nelson, D. Lee Petersen, Charles R. Nelson

INTRODUCTION The Soudan 2 Cavern was completed in 1986 as a physics research laboratory located 713 m below ground in northern Minnesota. A paper in the 1985 RETC proceedings presented the background and planned usage for the cavern, site investigation and rock conditions, contract documents, and a bid summary. This is a follow-up paper describing construction of the cavern. The Soudan 2 excavation, 71.8 m long by 13.9 m wide by 11.6 m high, was excavated by drill and blast methods and mucked by crawler tractor and mine hoist. The excavation sequence consisted of twin top-heading pilot tunnels followed by removal of the top heading pillar and finally the bench. Various blasting designs were used to achieve adequate breakage and acceptable levels of blast damage control at the cavern perimeter. The geologic conditions exposed in the cavern, and the support needs of the rock encountered, are compared to the conditions interpreted from the site investigation. The influence of specific geologic features on cavern performance will be described. Initial support and final lining consisted of full length grouted rockbolts and reinforced and plain shotcrete. Trials were conducted with steel-fiber reinforced shotcrete and microsilica additives. The performance of the rock and support systems was tracked with single point extensometers, convergence measurements

Jan 1, 1987

By Hasan Kolayli

Zeolites are common secondary components of a variety of igneous rocks. However it is extremely rare to reach such abundances to form a rock. An unusual rock composed almost entirely of natrolite, a zeolite mineral, has been discovered ; in a mountainous terrain called the Kop mountain range in the eastern Turkey. In the region, country rocks are essentially metamorphic rocks. These unique rocks are resulted through metasomatic changes acted on microdioritic and andesitic parent rocks occurring generally as dikes and stocks in the country rocks consisting chiefly of serpentinized harzburgites. These metasomatic rocks are investigated with respect to their mineralogical, petrographical, and geochemical characteristics. These products consisting dominantly of natrolite are termed "natrolitite" and those containing additional pargasite, an amphibol mineral, are termed "pargasite-bearing natrolitite or pargasitic natrolitite ". The dikes and stocks show concentric zoning, each of which has distinct chemical and mineralogical compositions: Na2O and H2O contents show enrichment outward from the core to chill zones whereas, SiO2 and CaO show depletion. Mineralogically, plagioclase variety, abundance and chemistry change outwards from the center due to partial to complete replacement of natrolite: anorthite contents of plagioclases decrease outward, which is indicated by A1203 and CaO decrease and SiO2 and Na2O increase, showing inverse relationship with increasing natrolite content.

Jan 1, 2005

By Edwin G. Johnsen

Underground mining is relatively safe today, but no technique or equipment is completely fool proof and 100% reliable. The only sure way to prevent accidental death or injury to underground workers is to remove them completely from the hazardous environment. This alternate approach to underground work is now feasible. Tunnelling and mining systems can be built that could be remotely controlled by men operating consoles in a surface control room. This concept, called a teleminer, would use recently developed remote control technology to remove man from underground work but still give him the capability to remotely operate mining and excavating equipment as if he were actually in the working area. It is appropriate to present this concept in the session "Environmental Controls" because the rationale for environmental control in underground areas can be significantly modified if man is excluded from the underground operation. The development of teleminers cannot only reduce or eliminate most of the requirements for conventional environmental control, but it can also create new and powerful techniques for rapid tunnelling and excavation. TELEMINER CONCEPT The concept of remotely controlled mining machines is neither new nor untried.(1)(2) Conventional remotely controlled mining equipment employs the standard techniques of extending the controls of the equipment to a remote console. For example, the rotary cutters on a remotely controlled tunnelling machine are started or stopped by a human operator turning a switch on the remote control console.

Jan 1, 1997

By Joyce A. Ober

Strontium occurs commonly in nature, averaging 0.034% of all igneous rock; however, only two minerals, celestite and strontianite, contain strontium in sufficient quantities to make its recovery practical, and these minerals are found in sedimentary rocks. Of the two, only celestite has been found to occur in deposits of sufficient size to make development of mining facilities currently attractive. Celestite, the most common strontium mineral, consists primarily of strontium sulfate (SrSO,). Strontianite, the second most common mineral, consists primarily of strontium carbonate (Sr CO3). Strontianite would be the more useful of the two common minerals because strontium is used most commonly in the carbonate form, but few deposits have been discovered that are suitable for development. The physical properties of strontium ores are listed in [Table 1].

Jan 1, 1994

By I. Dumitrescu

Since 1990, the entire Romanian mining industry has suffered a major restructuring, i.e. technical and economic. The large majority of the remaining active mines are these with a chance for economic comeback. This is also the case for the mines that belong to MINVEST Deva Company; most of the mines are closed, and are waiting to be reclaimed. The authors present the closing procedures of the former copper mining perimeters managed by MINVEST. It is well known that pollutants of concern for the environment must be monitored to obtain reliable information on the quality of ambient conditions and to minimize their impact on the environment. Consequently, the monitoring problems during the closing procedures will be presented.

Jan 1, 2008

By Milton E. Wadsworth, Ximeng Zhu

Impurity metals can markedly influence the anodic dissolution of gold in the presence of cyanide. Several important findings related to the influence of lead are reviewed and some new observations presented. Based on the effect of pH, the scan direction, and voltage, it may be shown there are three separate voltage regimes where lead influences the anodic dissolution of gold. These are related to Pb°/ HPbO2, Au-Pb /HPbO2, and HPbO2/PbC2; oxidation-reduction reactions which provide low resistance paths for electron exchange. The gold dissolution rate was determined by direct solution analysis and is compared to the rate implied by electrochemical measurements.

Jan 1, 2005