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By Robert M. Becker

The evaluation of in situ rock stresses from measurements of the change in diameter of a borehole that is stress-relieved by overcoring has become a common practice. Generally the stress evaluation has been based on isotropic relations whereas rock in varying degrees is anisotropic. A plane elasticity solution for a circular hole along one axis of an orthotropic medium has been adapted to evaluation of in situ stress. The necessary elastic parameters for this evaluation may conveniently be obtained from static tests on the overcore in conjunction with a consistent orthotropic thick-wall cylinder solution. The method and equations for the laboratory and field evaluations are summarized and illustrated.

Jan 1, 1968

By F. Milton Lewis

In this paper an attempt has been made to review the cost trends in producing copper by conventional milling. smelting and hydro-metallurgical means during the last five years. The primary objectives of this cost analysis are to provide a base for future projections as well as to indicate which cost items are more volatile in their influence on overall cost of producing copper.

Jan 1, 1977

By H. K. Conn

This paper discusses briefly the evaluation of chrysotile asbestos deposits in ultramafic rocks. Such deposits are limited to serpentinized peridotite and/or dunites. The purpose of any evaluation is to determine whether a deposit contains sufficient ore mineral to justify profitable exploitation. Dimensions of a mineral zone are established by conventional methods, such as mapping, ground magnetic surveys, diamond drilling or underground exploration. The value of the contained asbestos fibre Is dependent on numerous physical properties such as fibre length, strength, flexibility, as well as the actual amount of fibre present. The determination of grade is difficult. The Quebec Standard Test (Q.S.T.) is used to grade fibre according to the proportionate lengths of fibre present. A method of visual vein counting allows calculation of an approximate percent fibre together with a simulated Q.S.T. Various drilling methods are discussed, diamond drilling is favored. Bulk sampling is required to determine fibre quality. Correlation of visual techniques and laboratory methods are often difficult. Reasons for any variance are discussed. Underground bulk sampling of most potential ore zones is strongly recommended to confirm the viability of the property. Evaluation of slip fibre deposits requires greater reliance on laboratory testing as visual methods are difficult to apply. Cross fibre has greater inherent strength.

Jan 1, 1971

By John B. Patton

No academic program of reasonable duration can provide a geologist with all the skills that may be needed for applied work in industrial minerals, but any curriculum that does not provide background in such basic subdisciplines as mineralogy-petrology, stratigraphy, sedimentology, structure, and geomorphology will leave the practitioner handicapped. Enough geochemistry to understand materials requirements, and sufficient geophysics to utilize geophysical data, are essential. In addition to purely scientific considerations, the industrial minerals geologist must be able to evaluate economic factors and may be faced with legal, social, and political problems in land use, zoning, environmental protection, and reclamation.

Jan 1, 1981

By Ö. Y. Gulsoy, L. Ergün, I. B. Celik

"In this study, the studies to develop a flowsheet for a low grade chromite ore are presented. The existing concentrator had to be suspended due to the decreasing metal prices. The study commenced with mineralogy and liberation profile of the chromite. The valuable mineral is chromite and the major gangue mineral is forsterite together with small amount of brucite and calcite. Heavy liquid tests were performed on different size fractions without any acceptable success. The concentration tests were performed using teetered bed separator (TBS) +shaking table, spiral concentrator+TBS+shaking table for different grind size. Based on the test results, 100% finer than 0.4mm was found to be optimum for grind size. Comparison of alternative circuits showed that the performance of both alternatives would be similar. A flowsheet was designed and operated for as 25 tph trial circuit in the existing plant. The results showed that the performance of the plant predicted was very close to the actual plant data. The paper describes the methodology used, presents the experimental data and actual performance figures.INTRODUCTION Turkey is one of the largest chromite producers in the world. Since 1850, chromite mining found industrial applications and geographically spread along six different regions in Turkey. Although the reserves in these locations are not as rich as the big producers, they are regarded as very valuable due to Cr/Fe ratio in terms of chromite utilization standards (1, 2). In this period, significant portion of high grade (=35% Cr2O3), directly marketable ore deposits have already been produced. According to General Directorate of Mineral Research and Exploration (Turkey) data; 83% of the known chromite deposits of Turkey which makes 242 341 000 tons in total, is consisting from the deposits those have a Cr2O3 grade lower than 10%. Only 5% of the known deposits (13 087 000 tons) has a grade of directly saleable (2, 3). Gravity concentration methods are well-known processes for chromite beneficiation and there are plenty of plants in the world and Turkey using these methods. As different equipment combinations can be used for the same enrichment method, different methods can also be used in combination for plant designs (4). Beneficiation of low grade and problematic chromite ores may lead to use these method and equipment combinations (5, 6). Ore liberation, the grades of Al2O3, SiO2, FeO and Cr2O3 in the obtained concentrate, Cr/Fe ratio, some physical and chemical properties between gangue and minerals (i.e. specific gravity, magnetic property, color, etc.) designate the selection and combination of these methods and equipment (7)."

Jan 1, 2017

By Shiou-Chuan Sun

This paper is to be presented at the Annual Meeting of the American Institute of Mining, Metallurgical and Petroleum Engineers, New York, New York, February 18-22, 1962. Permission is hereby given to publish with appropriate acknowledgments, excerpts or summaries not to exceed one-fourth of the entire text of the paper. Permission to print in more extended form subsequent to publication by the Institute must be obtained from the Secretary of the Institute. If and when this paper is published by the Institute, it may embody certain changes made by agreement between the Technical Publications Committee and the author, so that the form in which it appears here is not necessarily that in which it may be published later.

Jan 1, 1962

By N. Langsford

The Archaean Yilgam craton has been a major gold province since 1888 with production and reserves of about 4700 tonnes. Production in 1994 was about 135 tonnes. The largest deposit, the famous Kalgoorlie Golden Mile, contains about 2000 tonnes of gold. About 40 deposits containing more than 35 tonnes (1Moz) of gold has been discovered so far in the Yilgarn. Most of the craton has deep weathering profiles inherited from previous tropical climatic conditions, modified by subsequent arid conditions. A mantle of transported material covers much of the variably stripped weathering profiles. Resolving the geology of the volcanic-sedimentary units (greenstones) and the structures that host the gold mineralization relies heavily on aeromagnetics and shallow drilling.

Jan 1, 1995

By E. B. Thorn

The production of portland cement requires that four basic elements -- calcium, silica, alumina and iron -- be ground to a fine powder, homogenized, and fed to the pyroprocessing unit, where it is burned to a cement clinker. The raw material must either be ground wet in a slurry form or dried and ground to a dry powder, with a fineness of approximately 85% passing the 200 M screen. According to the Portland Association's Plant Information Summary, approximately 38% of the U.S. capacity is ground wet and 62% ground dry. The following data is taken from the Portland Cement Association's 1981 Energy Survey: [Million BTU/Ton kW h/Ton Wet Process Plants 5.86 138 Long Dry Process Plants 4.97 123 Dry Preheater Plants 4.03 157 ]

Jan 1, 1984

By Paul T. Allsman, Paul F. Yopes

17.1--CURRENT AND FUTURE STATUS OF SURFACE MINING PAUL T. ALLSMAN AND PAUL F. YOPES 17.1.1--CURRENT The history of surface mining essentially is one of mining coal, copper, iron and aluminum ores, of placer mining gold and tin, and of pits and quarries producing clays, gypsum, phosphate rock, sand, gravel and stone. Table 17-1 is a summary of the estimated world and United States production of crude metallic and non¬metallic ores and coal in 1969. It includes estimates of the quantities produced by surface-mining methods. Two-thirds of the 10 billion tons are mined from the surface, ranging from a third of the coal. 57% of the metallic ores, and nearly all clays, stone, sand and gravel. Production by surface methods in the United States, parallels that of the world with one exception: about 90% of the copper and iron ore is mined from the surface, whereas elsewhere only about half the copper ore is surface mined. In Canada, surface mining of the Athabasca tar-sand deposits is a recent large-scale unique operation. In surface mining of coal and, to a lesser extent, metallic ores, much waste is stripped, but in nonmetallic pits and quarries the ratio between waste and ore usually is small. Assuming that the stripping ratio for surface mining in the

Jan 1, 1973

By A. G. Yapo, T. W. Camm

"Mining plays a key role in the development of modern civilization as a source of essential raw materials and provider of essential fuels, producer of jobs and a factor in support of the international balance of monetary payment (Camm, 2014). Professionals in mining locate, develop, design and manage ore deposits in an environmentally safe and profitable manner. As mineral deposits become increasingly scarce, new challenges face the industry. A current trend is to an increased emphasis on underground mining techniques for deeper deposits. Operations are safer now than before as companies understand better their work environment and the importance of mining responsibly.A continual challenge for the industry is accurately reflecting the costs and selling price of ore. An enduring characteristic of mining is the situation where the market typically determines the price of a commodity; the main control a company has on the bottom line is to control the cost of production.An attempt to bring light and clarity to the cost of their business will give a better idea to investors on the true profitability of the mining business. Gold producers face this struggle to accurately reflect the cost of production while also seeking to attract the interest of the investment community (Hill, 2013). In order to have a consistent format to report on their production costs, leading gold producers, through their alliance inside the World Gold Council (WGC), worked on the adoption of a new cost framework: the all-in sustaining cost (AISC) and all-in cost (AIC).Since 1996, the traditional cash cost reporting has focused only on the mining and processing costs incurred in mining an ounce of gold, which included the costs of goods sold (labor, energy, and consumables costs) and royalties (Table 1). But cash cost reporting ignores many important aspects, like sustaining capital, general and administrative expenses and site rehabilitation at the end of the mine life (Whelan, 2013). The cash cost was used to attract many investors into the business. In fact, the high gross margin (sales minus cash costs) has been promoted in past decades by the industry instead of the net or operating margin. As a result, even when the gold price was high, nearly $61/g ($1,900/oz) in August 2011, gold producers were not reporting excessive profits in their cash flow/income statements, to the disappointment and incomprehension of investors (Milstead, 2014). The truth was simply that the other costs omitted in the traditional cash cost were reducing the apparent profits.The disconnect led to a need for more accurate cost reporting in order to win back investor confidence and provide better understanding of gold mining economics. In 2012, the senior gold mining companies, including Gold Fields, Barrick Gold Corp. and Newmont Mining Corp., worked with the WGC to develop a new measure. This resulted in the June 2013 publication of the new framework AISC and AIC, which has been widely embraced by the sector since Jan. 1, 2014 (WGC, 2013).The adoption of the new cost template would have the dilemma of showing the real profitability of gold mine properties, which might alleviate taxes from governments and legislators, but it might also scare off investors toward more lucrative industries if not winning back their confidence."

Jan 9, 2017

By J. C. Purcupile

In this time of increased coal demand, a faster and safer method for roof support is needed. This report outlines the preparation and testing of a machine which we feel will help answer this need. The results of the tests are encouraging, and indicate that further exploration of the method should be continued.

Jan 1, 1975

By Hung-Kei H. Lam

Rubidium and cesium were discovered by Bunsen and Kirchhoff about 100 years ago. These two elements are by no means as abundant as sodium or potassium. Their occurrence in minerals is widespread, but usually as minor constituents. There is no known specific ore containing rubidium, but rubidium is found replacing the. other alkali metals in .some minerals.. Perhaps the highest concentration of rubidium found in one mineral is in lepidolite, KLi(OH,F)2A12Si3010, which contains from 0 to 3.5%*Rb20. 0n the average, lepidolite contains about 0.5% Rb20. Other sources of rubidium are carnallite, KMgCl3?6H20; pollucite, H20.2Cs20.2AI203.9SiO2; rhodizite, R20.2A1203-3B203; biotite, H2K(Mg,Fe)3A1(Si04)3; sea water, rivers, marine and fresh water organisms, soils, and plants. Cesium, even though it is the least abundant. of the stable alkalies, has a specific ore. Pollucites a hydrous cesium aluminum silicate, may con¬tain as high as 42.5% Cs20, although again, the average Cs20 content is about 25% among the handful of known deposits. Other cesium-containing minerals are lepidolite and carnallite. Rubidium and cesium are very much like potassium in chemical properties, consequently, they are hard to separate. Because of the difficulty in obtaining pure cesium and rubidium compounds coupled with the scarcity-of supply, prices were high and the two elements enjoyed little industrial use. Just before the Second World War, the world. supply of rubidium and cesium, from Germany, was a matter of tens of kilograms per year and prices were about

Jan 1, 1959

By Ronald W. May

The Lower Cretaceous McMurray Formation in northern Alberta contains bituminous sands interbedded with other sediments which form the reject encountered during mining operations. Grade prediction is based on a combination of geological interpretation, computer modelling and past mining experience. In addition to estimates for ore, an accurate estimate of "waste" or "reject," are required for Mine Planning. This study investigates the ability of point-kriging using geostatistics, to augment the existing data base of drill-holes in a study area on Syncrude's leases. This approach enables the assessment of potential "worst" case - "best" case scenarios within the context of Mine Planning.

Jan 1, 1985

By M. C. Baumann

The Getchell Mine is located in Humboldt County, Nevada, approximately 70 km northeast of Winnemucca. Slope management has been a critical factor in the feasibility of mining operations since they began in the early 1930's. Although underground entries began in 1937, underground production was limited because hanging walls consisting of clay gouge and crushed rock tended to collapse into the workings. Controlling these collapses required extensive timbering. Due to these poor ground conditions, surface open-pit mining was the primary mode of production from 1938 to 1967 with only minor contributions from underground operations. Mining was suspended in 1967 due to economic pressures. From 1960 to 1967, the previous operator mined the property in three open pits. Initially, these pits were constructed with footwall benches, but these failed. These failures were aggravated by construction of 60° slopes in footwalls with shale partings dipping into the pit at 43° to 60°, resulting in large planar failures and wedge failures. In response, the previous operator adopted a slope parallel to the bedding planes.

Jan 1, 1993

By Steve Kral

San Francisco, CA will host about 1,500 tunneling and underground construction professionals from around the world during the biannual Rapid Excavation and Tunneling Conference (RETC), June 19-22. These professionals are gathering in a city that has seen much under-ground work throughout its history. And, today, the San Francisco region has more than $4.6-billion in tunneling projects under way. The RETC will include three-and-a-half days of technical programming, complete with proceedings, two short courses, two field trips and a host of social activities. In addition, the accompanying exhibit has attracted 127 exhibitors in 152 booths, an RETC record. The following is a brief list of activities that will take place during the conference. A more complete program is provided in the official showguide that is bound into this issue of Tunneling & Underground Construction.

Jan 1, 2011

By Newell H. Orr

Titanium's performance characteristics in acidic oxidizing and mildly reducing environments make it applicable to numerous currently defined and many projected hydrometallurgical applications. With titanium's current and projected availability and price stability increased use in pressure leach, piping systems and electrorefining is practical.

Jan 1, 1983

By A. P. Gentsch

Commercially mined calcium carbonate is normally found near the surface in the United States. It is nun& either by open pit or underground methods, depending upon its geologic setting. Processing ranges from simple crushing to the more sophisticated ultrafine processes. Intermediate steps are pulverizing, screening, beneficiation, classification, fine and ultrafine grinding, and surface treating. These processes are performed both dry and/or wet resulting in powdered or slurry end products.

Jan 1, 1986

By David J. Dunn

Mill liner design is an important factor in grinding. Testing and selection of the optimum liner profile for a given set of mill operating conditions can improve mill capacity, liner life, and liner wear rate At a time when mill avilability is at a premium, production costs are going up, and lead time for mill liner castings is a year or more, the mill liner that grinds best, lasts longest, and costs least is a necessity for economic mill operation. In testing four mill liner profiles for 13' x 12' overflow ball mills, Climax found that an improved design increased mill tonnage by 3 tons per hour while reducing finish grind by 1.7% + 100 mesh, reduced liner wear rate, and almost doubled liner life.

Jan 1, 1976

By William Hodder, Ehsan Alavi, Muhib Hussain

Disc Cutter Wear is influenced by several geological and technical factors and excessive wear can have a major impact on the excavation efficiency of Tunnel Boring Machines (TBM). Disc cutter replacement events cause a disruption to the construction schedule and costs, and should be minimized throughout the project to the extent possible. A well-executed cutterhead inspection and maintenance plan can help mitigate abrupt cutterhead interventions and reduce its effect on project schedule and cost. This paper examines cutterhead inspection and disc cutter replacement events as well as subsequent wear data recorded in the first 7km of the 10.3 km long, 6.3 m diameter Coxwell Sanitary Bypass Tunnel (CBT) project in Toronto, Ontario. The CBT alignment is mainly through Georgian Bay Formation shale.

Dec 1, 2022

By Wendell E. Bearce

At the, Crescent Valley Mine of the Hanna Coal Company, several 10,000 ton unit trains of 41" x 0 strip coal are loaded per week during the lake season. This is accomplished without the use of any accumulation of prepared coal. A large raw coal pile is built up during the winter months adjacent to two truck dump bins. This is added to whenever trucks are coming in from the pits and trains are not being loaded. During the loading of trains, trucks from several pits dump into the truck hoppers and coal is also dozed in from the pile. At a rate up to 3200 tons per hour this coal is screened, the plus 6" hand picked, the plus 4" crushed, and' all weighed and sampled as it goes directly to railroad cars being handled on two tracks by car retarders. With such an arrangement it is possible to exercise some control over coal quality, if it can be assessed rapidly. For instance, if the moisture rises to a level where it seems probable the BTU per pound will be reduced to the point where the contract calls for penalties, the trucks from, the wettest pit may be stopped, more or less coal may be moved in from the stockpile, or other measures taken to assure that the average BTU of the trainload will be satisfactory.

Jan 1, 1967