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By Reeves T. J, Hansen J. Y

Dense medium cyclone theory, supported by extensive experimental and plant-scale evidence, demonstrates that medium rheology (stability and viscosity) substantially affects cyclone performance in mineral applications.Two instruments have therefore been developed to allow medium stability and viscosity to be-monitored in the plant environment. The instruments are described, and examples are given of their application in full-scale plants.

Jan 1, 1989

By N Boughen, P Ashworth, S Johns, C J. Yeats, A Littleboy

The ocean floor, often called the last frontier, is increasingly discussed in terms of its resource potential û from near shore building aggregate and placer deposits to massive sulfide orebodies in the deeper ocean. Consequently there is an increasing incentive to mine the seafloor. But, do we have the social license to explore and mine the seafloor? Does this nascent industry have support amongst the wider community? If not, why not? And what should be done? To answer some of these questions, the Wealth from Oceans National Research Flagship has explored the social viability of an expanded seafloor exploration and mining (SEM) industry inAustralia. The results show that there are significant geological and environmental data gaps and that, in the absence of sufficient information, stakeholder reaction to the prospect of an SEM industry expansion may be reactionary and negative. This uncertainty means that the perception of risk from the industry is variable and often dependent on individual values. The acceptability of an expansion to the SEM industry is currently precarious, in particular due to the high levels of uncertainty regarding the environmental impacts of seafloor activity. While there are existing federal regulatory frameworks and government processes for the licensing of seafloor mineral exploration and extraction, there is little precedent in the application and implementation of these regulations. The future viability of the industry will be highly dependant on AustraliaÆs ability to improve the knowledge-base underpinning its regulatory regime and also to generate open and transparent communication channels between stakeholders. It will also be dependent on the SEM industryÆs ability to communicate an acceptable value proposition to society. This proposition will need to include the relative impacts of terrestrial and marine mining, the alternative potential uses of the ocean and the multi-use conflict that SEM might engender. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Munro DL

The Mary Kathleen uranium deposit is in north-west Queensland, approximately halfway between the townships of Mount Isa and Cloncurry, at long. 1400 009 E and lat. 200 44' S. The deposit Iwas discovered by prospectors of the Walton McConachy Syndicate early in July, 1954, and climaxed a very intensive ground search by hundreds of part-time prospectors. during the uranium boom from March to July 1954ò Numerous small deposits, mostly in the vicinity of Mount Isa, were discovered in various rock environments, but Mary Kathleen is the only large deposit and, apart from a few tons of hand sorted material from the Milo lease, is the only deposit that has been worked. Exploration of the surrounding area, and proving of the economic worth of the deposit, were conducted from the time of discovery until February 1956 by a geological team camped near the deposit. Proving was carried out by drilling a pattern of vertical and inclined diamond drillholes at fifty-foot centres over the outcrop. An adit was driven eastwards through the deposit. Metallurgical research and design work in the South Australian Department of Mines Adelaide Laboratories were based on core samples and bulk samples from the deposit. The signing of a contract in March 1956 with the British Atomic Energy Authority to supply 4500 short tons of uranium oxide allowed mining to commence, and enabled the planned construction of water supply, township and treatment plant to proceed. The open out mine and plant are now serviced by a modern township, four miles away, which is connected to Cloncurry and Mount Isa by road. Although little field work has been done since the exploration phase, this paper differs in interpretation from a previous paper (Matheson and Searl, 1956) in that it is based on a revised structural inter- pretation (Compana, 1958), detailed mapping of progressive exposures in the open out, and a re-examination of diamond drill cores.\

Jan 1, 1968

By Andre Zingano

It is known that the backfilling confinement increases the pillar strength and also reduces the rib lateral displacement. With backfilling, it is possible to increase the room-and-pillar mining recovery. This paper aims to study the behavior of coal pillars confinement using rock fill as backfilling material. Laboratory tests were carried out to determine the behavior of backfilling materials. Constitutive models were developed for the tested backfilling materials. Numerical simulations for the effect of backfilling materials on the ground stability in room-and-pillar coal mine entry were performed. The backfill method is a good strategy to (i) improve the ground stability in room-and-pillar coal mines for long term, especially for weak coal seams, (ii) increase the coal mining recovery and (iii) reduce the quantity of waste material on waste piles at the surface.

Jan 1, 2011

By J Weir

Accurate sampling of slurry streams is extremely important for metallurgical accounting in mining operations, not only for measuring the ore grade from the mine, but also for measuring the recovery of mineral by the mineral processing plant. Accurate sampling is also required for intermediate streams in complex circuits for determining efficiencies of processing units within the plant. As the profitability of the minerals industry is squeezed more with time, greater emphasis is being placed on efficient use of the resource and accountability of the various sections of the mining operations. This has led to increased awareness and interest in obtaining statistically correct sampling across the operations. Accurate sampling is not only required for metallurgical accounting, but is also required for on-line analysis of the slurry streams for elemental analysis and for particle size. Sampling of slurry streams for metallurgical accounting purposes has traditionally been one of the areas of concern in mineral processing plants. In the first instance, the sampler must be designed to comply with the fundamental principles of sampling theory and must provide a representative sample of the slurry stream. In the second instance, the sampler must continue to reliably provide a representative sample, regardless of wear of the equipment or build up of solids with time and other operating issues. To-date the main type of sampler that has been used in mineral processing plants for metallurgical accounting has been the Cross-Cut sampler. These have a cutter that periodically cuts across the full slurry stream. For large flow slurry streams, these are often followed by a secondary and perhaps a tertiary sampler, to reduce the flow-rate or sample, to a manageable size. This paper discusses a new method of sampling slurry streams that has been developed by Thermo Gamma-Metrics, previously known as Amdel Instrumentation. The new samplers overcome many of the problems associated with cross-cut samplers while providing a sample which is representative of the main stream, throughout the life of the sampling system. The sampler is called the SamStat (Sampling Station) and it is now proven in many applications across many countries and mineral processing plants (PGMs, Cu/Au, Pb/Zn, etc).

Jan 1, 2002

By John C. Shyne, Eric R. Morgan

WHEN temper rolled low carbon sheet is stored at room temperature before use, changes take place in its mechanical properties. This phenomenon is known as strain aging. Normally these changes are observed by means of Olsen ductility and Rockwell B hardness tests but' unfortunately such tests are relatively insensitive. Strain aging can be readily observed in the laboratory by means of tensile tests. The tensile test method is even more sensitive if the aging is allowed to take place in specimens which have been prestrained in tension rather than by cold rolling. In fact one of the great benefits of commercial temper rolling is that it introduces a residual stress pattern which tends to mask the effects of strain aging when the sheet is finally used in a pressing operation. Curves B, C, and D of Fig. 1 illustrate the changes that take place during the aging of commercial rimmed steel at room temperature following straining in tension, curve A, Fig. 1. The first important change that can be observed is an increase in the stress required to produce plastic flow. This increase is, in this paper, called the aging index. As aging proceeds and the aging index increases, there is also an observable return of the yield point, an increase in the ultimate tensile strength, and a decrease in elongation to fracture. The results of strain aging in deep drawing steel manifest themselves as stretcher strains (L?ders bands) buckling, 2nd tearing. In deep drawn parts such effects are undesirable and strain aging is a serious problem. The rate of strain aging of a steel depends upon its composition and prior mechanical and thermal history? but for most temper rolled ope

Jan 1, 1958

By M. King Hubert

The growth of human knowledge is an evolutionary process. Historically our separate sciences came into existence as people became interested in various apparently unrelated domains of phenomena, and in this manner we acquired the sciences of physics, chemistry, astronomy, biology and geology. As various of these sciences became established, cognizance of them came to be taken by the universities and in this manner there arose the traditional departments of physics, astronomy, chemistry, biology and geology of our American universities. As there was no particular rationality in the boundaries separating the various sciences, in the university departments the jurisdiction of each has assumed quite arbitrary limits. In the domain of earth phenomena the first science to grow up was that of geology, which arose originally from the activities of the collectors of rocks, minerals and fossils. Thus geology evolved as a descriptive science dealing with directly observable terrestrial phenomena for which elementary rational explanations were offered. The traditional treatment of phenomena by the science of geology has rarely been with more than an elementary regard for the fact that these phenomena were also phenomena of physics and chemistry. Since the latter part of the nineteenth century, a new approach to terrestrial phenomena has been emerging and becoming of so great a significance that it can no longer be ignored. This approach has been made by people trained primarily in the sciences of physics and chemistry, who have investigated terrestrial phenomena as constituting phenomena of their respective sciences. In this manner we have acquired the so-called "borderland sciences" of geophysics, the physics of the earth, and of geochemistry, the chemistry of the earth. Neither of these fields is new, having arisen chiefly at the hands of European investigators during the latter part of the nineteenth century. The European universities have long since given official recognition at least to geophysics, by the establishment of departments or institutes of geophysics, which are on a par with the university departments of the other sciences.

Jan 1, 1940

By D. R. Dixon

Since the critical role of oxygen in xanthate flotation of sulphides was established (1) subsequent studies have been concerned mainly with the galena-xanthate system. It is therefore surprising to find at the conclusion of a comprehensive review of the topic by Granville, Finkelstein and Allison (2) that it was not possible for them to draw unequivocable conclusions on the mechanism of xanthate adsorption. It was apparent that some new advances were likely if systems other than galena-xanthate (Pbs/x-) were examined. (2) Specifically a less reactive sulphide such as ZnS may interact with flotation reagents at a slower rate than PbS and more information per unit time gathered. Again ZnS is far less reactive electrochemically than PbS or stated equivalently, it is a poorer semiconductor than PbS. More importantly, the ability of ZnS to act as a semi-conductor can be controlled photochemically rather than by direct doping reactions for which it is difficult to assess the uniformity of doping. Thus the conductivity of ZnS can be made the same as that of PbS by irradiating the ZnS with ultraviolet light at circa 360 n.m. (3)

Jan 1, 1974

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION This method is a variation of cut-and-fill mining where either the wall rock or the vein is too unconsolidated to permit safe mining by conventional cut-and-fill methods. Basic development consists of driving a 2.4 x 2.7-m (8 x 9-ft) haulage heading laterally in the footwall side of the vein. Crosscuts are driven over to the vein at 91-m (300-ft) intervals. Then the vein, at each inter¬section, is mined out to a distance of about 9 m (30 ft ) above the track level. After the installation of an ore chute, scrams or intermediate drifts are driven in both directions along the vein. Mining then starts imme¬diately below the level bounding the upper limit of the stope. A cut varying between 3 and 4.2 m (10 and 14 ft) in depth and mined for a distance of 45.7 m (150 ft )along the strike is taken from the orepass in each direction (Fig. 1). In this mined-out void, the floor of the cut is equipped with 203 x 203-mm (8 x 8-in.) caps hitched into the wall with steel saddle hitches installed on 1.5-m (5-ft) centers. Double wood stringers, 152.4 x 152.4 mm (6 x 6 in.), are then installed on 1.2-m (4-ft) centers longitudinally down the length of the stope. Reinforc¬ing wire mesh is also placed, overlying each mat of timber. Directly above the stringers, stulls are installed from hanging wall to footwall to hold the timber in place during the sand-filling operation. Then a cement¬sand mixture in a ratio of about 1:10 weight is poured to a depth of about 2.4 m (8 ft). The entire cycle is then repeated down to the scram drift. Another variation of timbering is illustrated in Fig. 2. There is a vein width of approximately 5.5 m (18 ft) with the same unconsolidated ground conditions. The primary difference between handling this situation and the previously described undercut-and-fill method is that standard timbered sets are installed in each excavated stoping void rather than stulls. Once again the basic method is to work down the ore block from an upper timbered drift to a lower timbered drift. Cuts are taken from a timbered raise with a chute on the stope side. Each piece of ground excavated is essentially two sets high, 5.5 m (18 ft), by two sets wide, 5.5 m (18 ft), by the length of the cut along the strike of the vein. The timbered sets are 2.4 x 2.4 x 2.4 m (8 x 8 x 8 ft). The net result is, therefore, two sets of timber on a top floor separated by doubled-up 76-mm (3-in.) lagging from

Jan 1, 1982

By Daryl R. Tweeton

The Bureau of Mines conducted experiments to measure the influence of environment on the friction and wear of a steel-quartz system at several speeds and loads. In each test a quartz block was pressed against a rotating ring of low-carbon steel. Environments used were moist air, dry air, dry nitrogen, water, aqueous oleylarnmonium acetate (ClsH35NH3+-OCOCH3), and aqueous aluminum chloride (A1C13). The sliding speeds were 2.2, 13, and 33, cm/sec, and the loads were 6.8 and 13.6 kg. The coefficient of friction, the wear, and the roughness of the surfaces were measured, and the wear debris was examined. The coefficient of friction was significantly lower in moist air at 2.2 cm/sec than for any other combination of environment and speed employed, and was generally an inverse function of the oxidizing ability of the environment. The coefficient of friction increased somewhat with increasing load. The wear of the steel rings was greatest in dry air at all speeds and loads. The wear of the quartz blocks at 180 rpm was greatest in dry air, but at 12 rpm it was greatest in nitrogen. Friction and wear in aqueous oleylarnmonium acetate and in aqueous aluminum chloride were similar to effect in water alone.

Jan 1, 1976

By O. S. True, C. H. Herty

It is well known that manganese will desulfurize molten iron through the formation of manganese sulfide, which, being only slightly soluble in the metal, rises to and enters the slag where it remains as such (mixer slag) or is converted partly or wholly to calcium sulfide (basic open-hearth slag). The reaction by which manganese sulfide is formed is Mn + FeS = MnS + Fe. This reaction is generally considered to be reversible, although McCancel states that such is not the case. The experimental work was carried out to confirm the results of Roh12 as to the reversibility of the reaction. Six trials are herein considered. In each 200 gm. of electrolytic iron free from manganese and sulfur were melted in a pure zirconia crucible in a carbon resistance electric furnace. To the melted iron in runs 2, 3 and 4 metallic manganese and manganese sulfide were added to give 1, 2 and 4 per cent. manganese respectively, with 0.50 per cent, of sulfur in each. In runs 5, 6 and 7, metallic manganese and iron sulfide to give the same proportions of. manganese and sulphur as in runs 2, 3 and 4, were added. The melts were held molten in the furnace for an hour and then cast into small ingots. The results of these melts are as follows: Ingredients of Charge Analysis or InRot ManOaneBe, SulfUR, ManOaneBe. SULFUR, Run Material Charged PeR Cent. PeR Cent. Per Cent. PeR Cent. 2 MnS + Mn............... 1.0 0.452 0.636 0.367 3 MnS + Mn............... 2.0 0.50 1.57 0.310 4 MnS + Mn............... 4.0 0.50 2.81 0.230 5 FeS + Mn................ 1.0 0.50 0.647 0.397 6 FeS + Mn................ 2.0 0.50 1.45 0.374 7 FeS + Mn................ 4.0 0.50 2.73 0.195

Jan 1, 1925

By Robert C. Steckley

The Bureau of Mines performed a fragmentation experiment in cooperation with Duval Corporation in a porphyry copper-molybdenum deposit near the Sierrita pit south of Tucson, Ariz. This experiment evaluated the fragmentation created in a 10-hole test blast having blasthole spacings of 25, 20, and 15 feet. The 10 blastholes were 9 inches in diameter and contained a total of 17,400 pounds of aluminized slurry blasting agent in 50-foot columns with 60 feet of stemming. Diamond drill core examination was the primary method used to determine the condition of the rock before and after blasting. These core examinations included study of length recovery, rock quality designation (RQD), weight recovery, and size distribution. Topographic surveys were used to measure the rock swell produced by the blast and a fragment size distribution was obtained for the broken material on the surface. Fragmentation to depths of 110 feet was excellent from the 15-to 20-foot blasthole spacing patterns. Good breakage was also produced by the 25-foot pattern although the effects of the blast were not so obvious. In situ leaching tests were not conducted. However, based only on size consideration, all three blasting patterns produced adequate breakage for successful leaching.

Jan 1, 1975

By J. S. McNeil, J. U. Messenger

In the drilling of oil wells the control and prevention of lost circulation of the drilling- fluid is a oroblem which is frequently encountered; in many cases existing materials and methods for alleviating this condition have not been adequate. For severe cases of lost circulation in which the simpler methods, such as application of various bridging materials to the mud system, have proven unsatisfactory. a new material and method for applying to the loss zones have been developed which appear to he superior to existing techniques in many respects. The material, called a clay cement, is capable of being handled as a drilling fluid after initial mixing of the solitl ingredients with water and may be pumped down the drill pipe and squeezed into loss zones. After a short period, the material develops a very high gel strength which seals off the zone against further losses of the drilling fluid. In field tests, the process has been demonstrated to be a very effective method for combatting lost circulation. INTRODUCTION Methods of treating lost circulation in rotary-drilled wells by the addition of special materials to drilling fluids have long been in the process of development and are continuing to improve.' However, the annual drilling costs which can be traced directly to lost circulation difficulties still run into the millions of dollars. The loss of mud materials into highly permeable zones may range up to $50,000 per well in some areas. In addition to mud costs, excessive requirements of casing, cement; rig time, and the attendant blowout hazards further emphasize the importance of the need for improved methods of combatting lost circulation. The shortcomings of presently-used materials and methods have led to the development of a new lost returns material in the form of a time-setting clay cement. In field tests this material has proven very successful in plugging off loss zones. which other more conventional materials had failed to do. REVIEW OF PRESENT CORRECTIVE MEASURES The proper control of such operating factors as pump pressure, clearance between pipe and hole, and speed of running pipe in a holez is of primary importance in preventing and minimizing lost circulation problems. These factors, however, concern matters of drilling technique and do not directly involve lost circulation materials. Aside from setting casing past loss zones, three principal methods are generally employed for the purpose of avoiding or combatting lost circulation: (1) adjustment in properties (principally density) of the drilling fluid, (2) addition of fibrous, flaky, granular or other types of bridging materials to the mud system, and (3) the application of cements to the loss zones. The latter method is usually employed only after the first two have proven unsuccessful. In Table I are listed some advantages and disadvantages of the common corrective measures. Frequently, a combination of bridging material and cementing material is used." This combination is based on the premise that a bridge will

Jan 1, 1952

By Heihachi Kamura

The reduction of iron oxide, such as Fe203, to iron in the blast furnace is performed principally by carbon monoxide, but partly by solid carbon by the two following reactions: Fe2O3 + 3CO = 2Fe 4- 3CO2 2Fe2O3 + 3C = 4Fe + 3CO2 It is known that reduction by carbon monoxide takes place at a much lower temperature than reduction by carbon and that the reducing action of earbon monoxide progresses to the inside of the ore in lump form by gaseous diffusion. In the reduction by carbon, however, the reducing action takes place only at the contact surface of the ore and carbon, so that the more complete the reduction by carbon monoxide, the more efficient is the operation. However, the reduction does not progress as shown in the foregoing equation, because carbon dioxide acts oxidizingly on the metallic iron to such a degree that when the gaseous composition reaches a certain proportion of carbon dioxide to carbon monoxide, the reduction practically stops, even though the gases are moving slowly through the heated ore. The proportions of carbon monoxide and carbon dioxide in the gas depend on the kind of iron oxide and the temperature of reduction, also on the duration of time in the reaction. The longer the time of the reaction, the higher the proportion of carbon dioxide obtained in the gas, but finally it will attain to a condition of equilibrium. Chemical Equilibrium of Iron, Oxygen, and Carbon Investigations concerning the equilibrium between iron, oxygen, and carbon have been carried out by E. Baur and A. Glaessner,1 who deter-

Jan 1, 1925

By C. O. Brawner

Introduction The procedures used to design slopes in rock have only been developed over the past 10 years. Therefore, continued review and assessment of field experience by the publication of case studies is necessary to determine the accuracy of the theory and the application of the design techniques being used. Where failures have occurred, mine management should insist that the slides be 'back analyzed' to determine the shear strength parameters at failure. These values should be used for any pit design as they reflect site conditions more accurately than any other procedure. The previous papers have dealt with the basic concepts and factors that influence stability. To illustrate the application of these concepts in the study of practical stability problems, six ease studies have been selected for review. The examples include failure of tailings dams due to an earthquake, failure and redesign of a slope in overburden, review of failures of rock slopes, calculation of the amount of seepage into a pit and influence of the groundwater on stability, and the design of slopes for a proposed 2,500 ft. deep open pit mine. All but the first example are drawn from the authors personal experience. EXAMPLE 1 Failure of Tailings Dams Due to an Earthquake On March 28. 1965 a serious earthquake occurred in Chile with the epicenter located near the town of La Liqua, about 80 miles north of Santiago. The earthquake had a rating of 7 to 7.25 on the Richter scale. A record of the acceleration was taken at Santiago where a maximum horizontal acceleration of 0.18 g. was recorded. Many small mines are located in this region. Each of the mines provided impoundment storage for tailings with one to three dykes. As a result of the earthquake, most of the dams failed. The most serious failure involved two dams at El Cobre where more than 2,700,000 cu. yd. of tailings flowed into the valley, travelled over 7 miles in a few minutes, destroyed part of the town of El Cobre and killed more than 200 people. The Chilean government commissioned an investigation into the failures. A summary of the findings was published by Dobry and Alvare7 in 1967 (1). The location of the earthquake and the tailings dams which were investigated is shown

Jan 1, 1971

By Stuart H. Ingram

The term lightweight aggregate implies material which may be substituted for the usual rock, sand and gravel commonly used as the major part of concrete, but distinguished by being much lighter in weight. Background The art of making and using concrete is old and well developed. Research and experience have pretty well determined the qualities necessary in its constituents, and time has tested theories and applications. Elaborate specifications and tests have been devised and generally adopted governing all phases of concrete work, from selection of material, through engineering design and down to mixing and placing. Standard practices have become routine to executives and laborers, and operations have been simplified and costs lowered. Though many lightweight aggregates meet the basic specifications necessary for usefulness, their physical qualities are so different that they fiequently will not pass standard tests, and some of them cannot be mixed and placed with the usual formulas for water and slump. As a rule their use produces a concrete with a lower modulus of elasticity which requires design change, and being produced in much smaller quantities than ordinary aggregate, production costs are higher. This latter works in a vicious circle to restrict their use and maintain prices that are not competitive, except as against each other. Increased Demand In spite of such handicaps consumption has grown steadily for the past two decades and is apparently growing even faster today. It is evident that lightweight concrete must have better qualities, and be sufficiently better to Overcome the higher cost and the other difficulties and disadvantages pertinent to the use of a new and different material in an old industry. Hence the study of its main ingredient should be of interest to all engineers. Our group has a double interest in the subject since most of the materials which have been used as sources of lightweight aggregate are either mined, Or are by-products of mining operations. We are directly interested in their production as well as their use, and since available supplies of materials suitable are limited, the increasing use, and rising demand, make the discovery of new Or or the development of processes to adapt other natural materials to this use, a promising field; and one in which our profession should take an active part. Recent Development Descriptions of ancient work contain references to the use of spalls of tuffs Or pumice in concrete masonry, but it is only since the nineteen twenties that serious attempts have been made to produce and market lightweight aggregates. A period of rapid advance in theory and practice in cements, mortars and con-

Jan 1, 1948

By Richard F. Hewlett

The mining industry utilizes a vast store of knowledge, wisdom, and engineering talent in designing mining systems. However, the complexity of the required systems and the presence of numerous variables frequently necessitates raking important decisions without having adequate accurately detailed information. That many of the decisions made in the past were nearly correct, in the long run, is substantiated by the number of successful mining enterprises that exist in the world today. Subsequent to 1940, the disciplines of operations research and systems engineering were developed. The disciplines have produced methods of providing better information to persons responsible for making decisions.

Jan 1, 1963

By Lloyd A. Morley, Robert Stefanko

The most time-consuming research segment was assembling the ref¬erences. These are provided immediately after the conclusions but are divided into two categories. The first is directly applicable publi¬cations, correspondence and personnel communications. The second listing contains those publications that are not directly tied to the research but where a probable application exists. In both listings, all important USBM publications are provided. The reference numbers used in the report apply only to the first reference portion. Further¬more, it should be noted that all entries are not used but are retained to help anyone who wishes to look further into different or allied areas of this research topic. Explosion-proof enclosures have been researched since approxi¬mately 1906. Even so, little is understood about the mechanism by which they are effective. Due to the voluminous literature published, there is a good probability that the assembled list is still incomplete. The literature search took the following directions. Work was first directed to reviewing the several references assembled by the Department of Mineral Engineering - Mining Section prior to the present project year. As a result, some duplications and inapplicabilities were found and eliminated. The primary sources of the previous search were the commonly available and usually superb library listings, such as Engineering Abstracts. Because these sources have enormous content on all subjects, they were cross-checked in the first semiannual period several times by different individuals to make sure all normally avail¬able literature were uncovered.

Jan 1, 1974

By Bill M. Stewart

To decrease the potential for fine coal waste slurry impoundment failures, the Bureau of Mines investigated a new disposal technique. The fine coal waste slurry is rapidly thickened (i.e., dewatered) and deposited on a slightly sloping surface. To accomplish rapid dewatering, a chemical flocculation system using polymers was developed to treat the fine coal waste slurry stream. The fine solids formed flocs, settled from suspension, and rapidly released excess water. During the last 5 days of the field test, slurry flowing at rates from 498 to 675 gal/min with a specific gravity range of 1.15 to 1.33 was successfully treated and dewatered. During this period, untreated slurry had an average moisture content of 227.4 pct (30.7 wt pct solids). The effectiveness of the dewatering system was determined by monitoring the moisture content of the deposited waste with respect to time. Sixty-five hours after ending the field test the average moisture content was 54.9 pct (64.5 wt pct solids); 68 days after the field test the average moisture content was 28.8 pct (78.0 wt pct solids).

Jan 1, 1986

By L. Kilpinen, K. R. Kay, H. B. Fowler

"FOREWORDThe International Nickel Company of Canada has built four ore concentrating plants since 1950. The fifth and largest is now under construction. In each successive plant, the level and type of instrument control and sophistication of control techniques have increased as experience was gained. The type of control progress is illustrated in Fig. 1.At Frood-Stobie the high degree of instrumentation and the level of control were made possible by the constant evolution of techniques and improved instrument hardware technology. We have established in practice concepts that are sound, although many modifications to instrument sensor types and locations 1-rere often necessary. It is generally true that at other existing Inco mills, it is possible to run ""all manual"" for protracted lengths of time because of operator availability and dependence. The Frood-Stobie Mill is the exception, and it is the degree of reliability of the instrumentation hardware and level of maintenance that has made this possible."

Jan 1, 1971