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By J. Harrison Daniel

More stringent dust standards, because of quartz in coal, have become a major compliance problem for the coal industry. Reducing quartz levels has become the major focus of the Bureau of Mines dust control research program. Results to date have identified hath the sources of quartz and prospective control technology. Control techniques are being developed for both room-and-pillar and longwall mining underground operations. Techniques include changes in face ventilation, mining cycle modifications, and better roof bolting dust control.

Jan 1, 1985

By L. Adler

When systematically compared to other engineering fields, mining engineering is distinctive in 1) having a total systems concern. 2) dealing with encumbered space and 3) requiring full spectrum practice. The total systems concern results from having to design and then co-ordinate in space and time several major systems: excavating and bulk handling, ground control, life support and normal support. This requirement favors a generalist rather than a specialist approach. In coping with encumbered space especially in underground coal mining, the uncertainties of geologic conditions are compounded by tightness, roughness, remoteness and hazards. Into this difficult setting the total systems * complex is "stuffed," adding congestion and interference. Because of significant ground deterioration a flexible "rapid in-out" approach is usually vital to mining. Full spectrum practice arises from the need to manage, as well as to plan and design, a labor intensive operation. Since market conditions can also fluctuate most aspects of administration are needed in many respects, mining engineering functions relative to civil engineering in a way similar to industrial to mechanical engineering, with encumbered space being crucial. On this basis stress is placed on: 1) personal relations, 2) field work and 3) entrepreneurship, viewing time as money. Specific recommendations for improving engineering, safety and management and leadership are made. Since most new deposits are marginal, by applying these recommendations with high technology they could possibly now be mined on a widespread basis.

Jan 1, 1985

By David A. Roberts, Edward J. Cording, James W. Mahar, Robert A. Robinson, Noppadol Phienweja, Harvey W. Parker

Horizontal inclinometer and deflectometer casings were used to measure deformations up to 15.2 m (50 ft) ahead of and adjacent to the heading in highly fractured and sheared shales at the Stillwater Tunnel. The measurements were compared with borehole extensometer and tape extensometer deformations to evaluate ground movements in advance of, adjacent to, and behind an advancing tunnel heading. Ground deformations of up to 127 mm (5 in.) occurred during passage of the innovative "walking blade-gripper" TBM. Deformations were compared with curvometer/distometer and vibrating wire strain gage data from steel ribs to assess rock-support interaction.

Jan 1, 1985

By Jeffrey J. Daniels

Advances in borehole geophysical research for mineral assaying, and remote detection of mineralization away from the borehole. Nuclear activation measurement research has provided accurate in situ assays of economic metals with neutron-gamma activation, using a high resolution intrinsic-germanium detector. Although nuclear activation analysis is the present "best-hope" for obtaining in situ assays for some elements, gamma-gamma and magnetic susceptibility measurements can provide accurate assays for lead-zinc and magnetite, respectively. Borehole optical spectroscopy and x-ray fluorescence are being investigated as possible in situ assaying techniques for some minerals. More laboratory and field calibration research is needed before nonlinear complex resistivity (NLCR) can be routinely used as a quantitative assaying tool. Field tests have shown that variations in the local geologic environment can affect the quantitative accuracy of assay values from downhole NLCR measurements. Deeply penetrating borehole geophysical methods are increasingly being used for mineral exploration as drilling costs and exploration have increased. Borehole electrical measurements have been shown to be useful for detecting conductive orebodies that are not interesected by a drillhole. Hole-to-surface resistivity, and surface-to-hole time-domain electromagnetics are demonstrated to be particularly effective for defining mineralized zones in a massive sulfide environment. Borehole gravity meters and three-component magnetometers have been developed and should prove useful for defining geologic anomalies away from the drillhole.

Jan 1, 1985

By John L. Bolles

The mineral processing engineer must have some knowledge of mineral identification, and the greater his knowledge in this field, the greater will be his potential to do his own specialty well. Most metal-bearing ores and industrial minerals require processing of some kind to produce a salable product or a material suitable for further processing. The types of treatment are many, but each one is aimed at separating a mineral or family of minerals from others. Obviously, then, it is basic to all mineral processing to identify the minerals present in the raw material and in intermediate and final products resulting from processing. Very often the mineral processing engineer will enter planning while exploration of a mineral prospect is going on. He will examine hand specimens, drill cores and cuttings, bulk samples, and materials in place. He must identify the valuable minerals, their occurrence and associations with other minerals, and the identity of diluents or host rock. An exact and detailed knowledge of the raw material will usually suggest the treatment processes that should be investigated in the development of the most suitable scheme for that particular raw material in that particular location. Physical properties of a mineral often lead directly to a process for separating that mineral from others. Some well-known examples of these are: magnetic separations for such minerals as magnetite, rutile, ilmenite; gravity separations for gold, silver, galena. cassiterite; flotation separation for most sulfides; distillation of mercury from cinnabar; and selective dissolution in specific solvents such as halite or sylvite in water, gold and silver in cyanide solutions, copper oxides, carbonates, sulfates and silicates in dilute sulfuric acid. These processes and many others are described in detail elsewhere in the Hand¬book and so it is not appropriate to give details here, except to emphasize that processing is aided greatly by complete mineral identi¬fication. Developing a treatment scheme for a new mineral discovery is an exciting assignment fag the mineral processing engineer, but much more of the usual work relates to quality control in existing plants. Here too, mineral identification is important. Some processing is aimed toward producing an end product which will meet exacting specifica¬tions regarding purity or allowable diluents. In this situation it is vital that contaminants be identified so that the process can be adjusted

Jan 1, 1985

By J. Jeffrey Wagner, Michael J. Bailey, Peter M. Douglass

The Chambers Creek Interceptor Sewer Tunnel project consisted of 2-1/2 miles (4 kilometres) of nominal 9-foot (2.7-metre) O.D. tunnel driven through predominantly glacially overridden soils. Mole-Collucio Construction Company initially elected to drive the entire tunnel with a Lovat TBM. However, this machine could not control the fast raveling ground conditions which developed when the TBM encountered sands overlying very dense, hard glacial till or boulders. As a result, a shield and digger machine was brought in for a 1700-foot (518-metre) long segment. Pumped wells spaced roughly 50 to 125 feet (15 to 38 metres) apart were utilized to dewater about two-thirds of the alignment during construction. Initial support consisted of steel ribs and wood lagging, with a final lining comprised of pre-cast concrete pipe segments grouted in place.

Jan 1, 1985

By J. L. Vanderbeek

Investigations have been conducted at Chino Mines Company into the effect that SAG mill recycle material (critical size) exerts on SAG mill throughput and specific energy requirements. Tests were conducted on the laboratory, pilot, and plant scales, to evaluate the merits of alternative treatment options. Removing critical size material from the SAG mill circuit has been shown to improve new feed rates by 34% with a reduction in specific energy (kWh/ton) of 33%. Test results obtained to date are presented.

Jan 1, 1985

By J. Iannicelli

Kaolin tailings ponds play an important role in reclamation of land and water. Discharges impounded from kaolin plants include oversize fractions consisting of coarse kaolin, mica, quartz as well as magnetically extracted contaminents, acid filtrates, and plant washdown streams. Tailing ponds perform an essential function in sedimentation of particulates, blending and reoxygenation of liquid waste, and neutralization and clarification of discharge water. During the past fifteen years, most kaolin firms have segregated their coarse filler waste to allow for possible reclamation for production of delaminated coating clay. This excess coarse filler fraction constitutes a reserve for future coating clay production.

Jan 1, 1985

By E. W. Lindroos, Fred D. DeVaney, R. L. Bennett, R. W. Hernlund, W. R. van Slyke, W. F. McDermott, C. U. Keranen

INTRODUCTION Iron is the world's most widely used metal and constitutes about 5% of the earth's crust. Iron ores are found widely distributed throughout the world. Because of its wide occurrence and relatively low value, an iron ore to be merchantable must contain a relatively high percentage of the metal to be considered as a source of iron. Few ores containing less than 25% iron would be considered as ore unless they existed in large amounts and could be concentrated very cheaply. The grade of the ore, the ease of concentration, and the transportation cost to market are fundamental considerations deter- mining its worth. Iron never occurs as a natural metal except in meteorites. Most iron ores occur as oxides, and to a lesser degree as carbonates. A small amount is recovered as a byproduct from iron sulfides. Iron ore must be reduced (oxygen removed) to metal for use. Iron is marketed in many forms and combinations, such as pig iron and a great variety of steels. Iron is practically never pure as marketed but contains varying amounts of carbon, phosphorus, sulfur, and alloying elements such as nickel, chromium, etc., all of which affect the physical proper- ties of the end product. Please note that in this section all analyses ore on a dry basis and all tonnage figures are on a long-ton basis of 2,240 lb unless otherwise noted.

Jan 1, 1985

By Tony Szwilski

A correlation between the rank, ash content and coal seam discontinuities and coal strength/stiffness is discussed. Rebound hammers were used to evaluate the strength properties of two coal seams. The coefficient of variability of the rebound tests are compared with those of laboratory compressive strength tests by other investigators.

Jan 1, 1985

By J. R. Walls

The United States potash industry had its beginning in the early Colonial days. Potash was initially manufactured by leaching of hardwood ashes in large iron pots. Production of potash was recorded as early as 1631 in New Hampshire, and in Maine a few years later. According to the census of 1850, the production of potash was America's most thriving chemical industry and, at that time, 569 plants were reported producing potash from wood ashes. Interest in potash was so great prior to the 1800's that the very first United States patent, signed by George Washing- ton, was granted for the production of potash on July 31, 1790. A new era for the production of potash began when potash was discovered by the analysis from a brine well in 1839 near Stassfurt, Germany while exploring for salt. The predominant use of potash at that time was in the chemical industry rather than agriculture. The discovery, by Justice von Liebig in about 1858, that potash salt contributed greatly to the essential plant food in soil opened up an enormous potential market for a suitable potash material.

Jan 1, 1985

By Joaquin Ruiz

Naica consists of at least 10 mantos and 40 chimneys that have produced over 15 million tens of ore with 10% Zn, 13% Pb and 13 oz/ton Ag. The ore occurs in thick-bedded, folded Cretaceous limestone. Fractures and 26 Ma old felsite dikes with an initial strontium isotopic ratio of 0.708 localize the mineralization. The mantos follow the dikes and have abundant early skarn with manganohedenbergite, calcic garnet, idocrase, quartz, calcite, wollastonite, schellite and later sulfides. The chimneys arise from the mantos and change from silicate-rich to silicate-free sulfide limestone replacements. Carbon, oxygen and sulfur isotope data on carbonates, silicates, sulfides and sulfates are compatible with a single evolving (magmatic?) fluid.

Jan 1, 1985

By James M. Barker

No commodity agreements now exist for sulfur and a lack of reference to sulfur commodity agreements exists in the literature. Law (1975) made a passing reference to sulfur as one of a group of commodities where "there have been additional control efforts of various types." Clearly, sulfur was a candidate, at least conceptually in the past, for some form of commodity agreement and the following discussion centers on the world sulfur market of the early 1980's in this context. GENERAL THEORY OF COMMODITY AGREEMENTS The upsurge in demands for commodity agreements seen in the last decade or so stems largely from agitation by the less developed countries (LDC) for better economic treatment by more developed countries (MDC). Several economic factors, real or imagined, adversely affect the LDC's as follows (MacAvoy, 1977): 1) variable demand in MDC's causes wide fluctuations in commodity prices which hurt the economies of commodity producers, who are often LDC's although consumer economies may also benefit from more predictable prices; 2) a general decline of commodity prices relative to the price of manufactured goods which hurts commodity producers in their balance of trade while their stocks and overcapacity rise; 3) instability of LDC economies enhanced by the above factors lowers internal stability, inhibits foreign investment, and retards economic growth; and 4) a lack of self respect when dealing with developed countries o, following the OPEC lead, LDC producers want the stature related to cartel market power.

Jan 1, 1985

By W. R. Penney, J. M. Richardson, J. Y. Oldshue

Introduction The mining industry has for years underrated the value of mixing in mineral processing unit operations. In present-day operations where leaching is playing an ever increasing role in the total profit picture, the need for good mixing is becoming more obvious. The engineer in the research laboratory and in the operations is by necessity becoming more familiar with the concepts of mixing. This section is designed to provide the engineer with mixing data and correlations sufficient to assist in the general planning of simple mixing systems.

Jan 1, 1985

By Janet Briggs, Michael Vertes, J. F. Shirley, R. E. Cutherbertson, Alexander Sutulov, J. D. Vincent

Molybdenum, the 42nd element in the periodic table, is now a very important metal in industry of the United States and the world. Chemically, it is a very complex element having valences of 0, +2, +3, +4, +5, and +6, and can exist as a mixture of these valences in many compounds. It was discovered and separated by Scheele in 1778. At the present time, molybdenite is the only important commercial source of molybdenum. Molybdenum occurs in some 12-14 different recognized minerals, but practically all of the production is molybde¬nite. As late as 1915, it was considered a rare metal. Germany made extensive use of it during the first world war, which resulted in the establishment of a molybdenum industry in the United States at Cli¬max, Colo., in 1917. It was not until the mid-1920s when its introduc¬tion to steelmaking developed for the US automobile industry that the metal gained important acceptance. The first notable example was the Willis-Saint Claire automobile introduced in 1921 by C. Harold Willis, formerly chief metallurgist for Ford Motor Co. Molybdenum has also been produced in the US from wulfenite (PbMoO4) from Arizona and Nevada, and a small amount of molyb¬denite was produced up to the early 1970s as a coproduct from two molybdenum-bismuth mines in Quebec, Canada. The first byproduct production of molybdenite from a copper con¬centrating operation was achieved at Cananea, Sonora, Mexico, and was followed shortly by the Utah division of Kennecott Copper Co. in the mid-1930s. This section of the Handbook is divided into four main subdivi¬sions: Chapter 2, which deals with the concentration and recovery of molybdenite from primary molybdenum ores; Chapter 3, which deals with the recovery and separation of molybdenite as a byproduct from copper production; Chapter 4, which deals with the conversion practices employed for converting molybdenite to the oxide or metal form; and Chapter 5, which covers the uses of molybdenum in steel¬making, chemicals, pigments, lubrication, catalysts, etc. The Free World molybdenum production, for the past eight years from all sources, is shown in Table 1. 2. Primary Molybdenite Ores General In 1978 there were four primary molybdenite recovery plants in operation: Climax, Endako, Quests, and Henderson. For over half a century the Climax mine has been by far the largest and most important source of molybdenum in the world. During the early 1970s a few primary molybdenite mines in British Columbia were shut down due to adverse economical conditions. The largest of these was British Columbia Molybdenum, formerly owned by Kennecott Copper Corp. The Climax plant and operations are described in detail and the opera¬tions of the other plants are summarized following a general discussion of recovering molybdenite from primarily molybdenite ores. Recovery of molybdenite as a byproduct will be taken up in Chapter 3. Geology Molybdenite production from mines in which it is the sole or preponderantly important mineral is confined to ore bodies in granites or igneous-type rocks or pegmatite dikes. More than one state of mineralization is sometimes present as at Climax, York, Hardy, and Questa. In the case of Climax, important byproduct recovery of tung¬sten, tin, pyrite, and monazite is also attained. The molybdenite is commonly disseminated very finely in the siliceous granitic gangue but does occur in stringers and blebs in silicified mineral solution channels. Treatment of Primary Molybdenum Ores All primary molybdenum ores are low in molybdenite, the content ranging from less than 0.20% MoS2 to a high of about 0.40% MoS2. A high resistance to grinding is a common ore characteristic combined with a habit of very fine dissemination of molybdenite in the siliceous portion of the ore. Because of low MoS2 content, high hardness, and fine dissemination of molybdenite in primary ores, it has been necessary to develop a special mill treatment which yields an accepta¬ble recovery at a reasonably low milling cost. Essentially, the treatment consists of intensive rougher flotation at a relatively coarse grind with production of a low grade rougher froth containing a substantial percentage of the molybdenite in the form of low grade middling particles, followed with multistage regrinding to liberate the locked molybdenite and several stages of flotation cleaning to produce a finished grade concentrate. Rougher flotation on pulp ground to ap¬proximately 35 mesh is common practice, even if complete liberation of molybdenite from siliceous gangue may require regrinding to 200 mesh. The flotation of middling particles with a very low content of molybdenite in the rougher flotation step has been made possible by the application of a combination of reagents first developed at the Climax mill and used with some modification in the treatment of all primary molybdenum ores. The reagents commonly employed and their functions in flotation are:

Jan 1, 1985

By D. G. Purdy

Planning, as defined in Webster's New Collegiate Dictionary, is a detailed program of action designed to achieve an end. When developing a detailed plan to incorporate all the complex activities involved in a surface lignite mine, many elements must be carefully evaluated as to the individual and cumulative effects on the end result. The following elements are generally evaluated when planning a surface lignite mine: ? Reserve evaluation, including lignite quality characterization; ? Delineation of mining parameters, including lignite recovery factors, geotechnical factors, land control factors; ? Selection of mining blocks; ? Pit sequencing; ? Reclamation, including soil reconstruction design and land use planning; ? Overburden handling design; ? Selection of equipment; ? Sizing of equipment; ? Manpower requirements; and ? Other elements, including contract negotiations and execution, financing, investment return, operation economics, permitting and scheduling.

Jan 1, 1985

By S. Acar

The results obtained for the selective flocculation or flotation of natural ores do not usually agree with the corresponding properties of the constituent minerals when present alone. This is mainly due to the presence of dissolved mineral species which can interact in many ways with other components in the system and alter their behavior. In this paper, the effect of dissolved species on the flocculation and electrokinetic properties of sulfide minerals is disscussed. Dissolved Fe, Cu and Ni species are found to affect the properties of chalcopyrite, pentlandite, millerite, pyrrhotite and covellite in certain pH range. These effects are interpreted in terms of species adsorption leading to activation or depression of reagents, surface precipitation and complexation of species, etc.

Jan 1, 1985

By L. M. Pero

The paper summarizes aspects of the recent literature on mineral development in the Third World. The emphasis is on publications covering agreements between host governments and mining companies.

Jan 1, 1985

By J-M M. Rendu

Geostatistics are increasingly recognized as powerful tools for reserve evaluation and grade control. It is also generally accepted that geologic input is required for the results of a geostatistical study to be meaningful. The role of the geologist is significant at all stages, whether it be to oversee the creation of the database, to assist in the statistical and semivariogran studies, to ensure appropriate block evaluation and kriging, or to review the results obtained. However the link between geology and geostatistics is often complex and not well understood. A presentation is made of the areas where geologic input is needed, and of the tools which the geologist should have at his disposition to ensure that his role is fulfilled. Organization of a Geostatisticel Study To be acceptable as the basis for financial investment, a geostatistical reserve estimation should be composed of four phases, the last phase being optional: Phase 1 - Background discussions, Phase 2 - Computation, Phase 3 - Reserve reporting, Phase 4 - Reserve audit. During the background discussions (Phase 1) the role of the geologist is primordial, as it is then that most decisions will be made concerning the geologic factors to be included in the geostatistical model.

Jan 1, 1985

By C. M. Brown

The semi-autogenous grinding circuit at the Utah Mines Limited, Island Copper Operation, located on Vancouver Island, British Columbia, is described. Since start-up of the operation in 1971 grinding circuit throughput has been progressively increased from the initial design rate of 30,000 to the current average 45,000 tonnes per day (t/d) of porphyry copper ore. Key developments and modifications in operating and maintenance practice that have contributed to this increase are reviewed.

Jan 1, 1985