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By I. Lowthian Bell

THERE has been probably no improvement introduced into the manufacture of iron which created more surprise in the minds of practical smelters and of scientific men than Neilson's discovery of the hot blast. In 1829, Messrs. Dunlop & Co. consumed at the Clyde Works, near Glasgow, nearly 7 3/4 tons of coal to make a ton of pig iron, of which about 20 cwts. was employed under the boilers of the blowing engines, leaving nearly 7 tons for the consumption of the furnace itself. In the year 1833, by heating the air to 612° F. (322° C.), they reduced the 7 3/4 tons to 3 tons by the mere burning of 8 cwts. of coal in the apparatus for raising the blast to this temperature. The statement just given is strictly true in a commercial sense, but when we come to consider the question as one of physical science, it is necessary to eliminate some of the conditions which conduced to so extraordinary a result. Anterior to Neilson's time the fuel employed in smelting iron was coke, and it was supposed at that period, erroneously, however, that coal in its raw state, when burned with cold air, was totally unfit for the purpose in question. This mineral, as it was obtained from the Lanarkshire coal-field, contained about 35 per cent. of volatile matter, but the process of charring it was performed in so unskilful a manner that instead of receiving 88 cwts. of coke from 135 cwts. of coal, 60 cwts. only was the product of the operation. Again, the reduced consumption of carbon in the furnace itself was accompanied by a corresponding diminution of blast, and this was followed by an economy of half a ton in engine coal. After making a proper allowance, however, for all these collateral circumstances, we are within the mark when we admit that in actual coke, which is really the form the fuel has to assume before it is burnt in the blast-furnace, not less than 30 cwts. was saved by heating the blast to 615° F. (322° C.). This unexpected economy, be it remembered, was obtained by the combustion of the 8 cwts. of coal, somewhat wastefully applied in the hot-air apparatus. Numerous have been the opinions advanced by different authorities in the scientific world to account for the apparent anomaly, but none,

Jan 1, 1877

By T. A. Wright

The sampling of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grat) sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases rnuch material can bc sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to incrcase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to makc sorting and grading more difficnlt in turnings, borings, clippings, etc., and conseqllcntly is making sampling of more moment. In tin, lead, alumiinum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosscs, battery lcad, and aluminunl skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or "metallic yield." Coppcr and Icad wastcl, howcvcr, is being sold more and more on actual copper and lead contents bascd on sarrlple and chemical analysts. This paper will be dcvotctl chiefly to the sampling of niaterials suitablc only for refining and recovery of one or more of the metals present. The methods described are often bascd on thc fact that but one, metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect thc final copper result, as the "after-melting" assay can be readily calculated to the "bcfore-nltltingl' basis, but if smelter efficiency continues to increase, so that in tiltie zinc, for instance, may be rccovrred on a paying basis, thc method of sampling dirty brass, for example, will have to bc changed also. As a matter of fact, we may cxpect that improved refining proresses will make possible the partial reeovrry of lcad and tin which are now lost

By I. Lowthian Bell

THERE has been probably no improvement introduced into the manufacture of iron which created more surprise in the minds of practical smelters and of scientific men than Neilson's discovery of the hot blast. In 1829, Messrs. Dunlop & Co. consumed at the Clyde Works, near Glasgow, nearly 79 tons of coal to make a ton of pig iron, of which about 20 cwts. was employed under the boilers of the blowing engines, leaving nearly 7 tons for the consumption of the furnace itself. In the year 1833, by heating the air to 612' F. (322' C.), they redoccd the 79 tons to 3 tons by the mere burning of 8 cwts. of coal in the apparatus for raising the blast to this temperature. The statenlent just given is strictly true in a commercial sense, but when we come to consider the question as one of physical science, it is necessary to eliminate some of the conditions which conduced to so extraordinary a result. Anterior to Neilson's time the fuel employed in smelting iron was coke, and it was supposed at that period, erroneously, however, that coal in its raw state, when burned with cold air, was totsally unfit for the purpose in question. This mineral, as it was obtained from the Lanarkshire coal-field, contained about 35 per cent. of volatile matter, but the process of charring it was performed in so unskilful a manner that instead of receiving 88 cwts. of coke from 135 cwts. of coal, 60 cwts. only was the product of the operation. Again, the reduced colisumption of carbon in the furnace itself was accompanied by a corresponding diminution of blast, and this was followed by an economy of half a ton in engine coal. After making a proper allowance, however, for all these collateral circumstances, we are within the mark when we admit that in actual coke, which is really the form the fuel has to assume before it is burnt in the blast-furnace, not less than 30 cwts. was saved by heating the blast to 615° F. (322° C.). This unexpected economy, be it remembered, was obtained by the combustion of the 8 cwts. of coal, somewhat wastefully applied in the hot-air apparatus. Numerous have been the opirlions advanced by different authorities in the scientific world to account for the apparent anomaly, bat none,

By T. A. Wright

THE SAMPLING of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or "metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can he readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also. As a matter of fact, we may expect that improved refining processes will make possible the partial recovery of lead and tin which are now lost.

Jan 1, 1928

By T. A. Wright

The sampling of waste materials containing copper, lead and tin has taken on a new significance within recent years, and is of increasing importance, on account of the entry of some of the copper refineries into this field and the tendency towards consolidations among the smelters. In the past, such material was sold on the basis either of a rough or grab sample or of casual inspection of the lot. The two principal sources of this waste are the processes of fabrication and the scrapping of automobile, electrical, plumbing, railroad and other equipment. In both cases much material can be sorted, salvaged and sold by classification and grade to be melted "as is" or with the addition of new or virgin metal. The increasing care in classifying exercised in the large manufacturing plants tends to increase the proportion of this usable scrap; on the contrary, the increasing use of more complex and special non-ferrous alloys tends to make sorting and grading more difficult in turnings, borings, clippings, etc., and consequently is making sampling of more moment. In tin, lead, aluminum, and zinc furnace by-products such as ashes, drosses, skimmings, etc., the trade practice of evaluation has not varied much. For instance, tin drosses, battery lead, and aluminum skimmings are ordinarily sold on what is called "metallic button" or "metallic recovery" or ('metallic yield." Copper and lead waste, however, is being sold more and more on actual copper and lead contents based on sample and chemical analyses. This paper will be devoted chiefly to the sampling of materials suitable only for refining and recovery of one or more of the metals present. The methods described are often based on the fact that but one metal, such as copper, is to be paid for. The loss of volatile constituents in melting does not appreciably affect the final copper result, as the "after-melting" assay can be readily calculated to the "before-melting" basis, but if smelter efficiency continues to increase, so that in time zinc, for instance, may be recovered on a paying basis, the method of sampling dirty brass, for example, will have to be changed also. As a matter of fact, we may expect that improved refining processes will make possible the partial recovery of lead and tin which are now lost.

Jan 1, 1928

By Paul D. Tomlingson

Modern production equipment has been designed with greater productive capacity and higher reliability to meet the rigorous operating demands of the mining industry. These improvements have also made the equipment more complex and challenging to maintain. Whether these equipment enhancements contribute to more effective mining operations depends on the overall quality of maintenance. Maintenance is not a stand-alone activity. Although its quality depends primarily on maintenance, cooperation and support from other departments, coupled with the skillful guidance of mining managers, greatly influence maintenance success. Therefore, maintenance risk management must look beyond maintenance itself. Successful maintenance risk management begins with an assessment of the maintenance-related interactions of all mining departments within the mine’s stated operating strategy.

Jan 1, 2005

By Bertrand Wolfman, William E. Stanley

"This paper reviews the traditional mine accounting systems, including ""custodial accounting"" and unit costing, and then suggests that the use of flexible budgets represents a more suitable method of reporting costs in order to assist the mine manager in improving productivity. Examples of various applications are given to show that the result is a clear reporting structure.Custodial Accounting is Emphasized in Traditional SystemsTraditional mine accounting has been mainly concerned with the accuracy of financial reporting to ""head office"" for the use of the directors and the company's bankers and shareholders. This is often called custodial accounting and it represented the main purpose of accounting when first developed in Europe hundreds of years ago. This important development permitted the establishment of enterprises which were separated from their owners because they could rely on accurate financial reports of management's stewardship.As custodial accounting is fairly broad and historical in nature, it is often not very useful to the mine manager for ongoing monitoring of performance of mining, milling, maintenance, and other support and staff groups. In spite of the considerable investment in accounting staff and computer support, many accounting systems have not been upgraded so that they accurately reflect workplace performance on a weekly or monthly basis.Budgets are Often FixedMany mines today also still emphasize fixed budgets. Thus, the mine plan which is set in the fall of one year is converted to a monthly tonnage and detailed dollar budget for periods of up to sixteen months in the future. The only certainty in this plan is that actual events will differ; timing, mix of mining methods and production volumes will differ on a monthly basis.Unfortunately, the fixed budget has no capability to reflect these operational changes. It is frozen for the full year. The result is that actual results will inevitably be compared to an outdated target."

Jan 1, 1982

By L. A. Rapoport, W. J. Leas, C. W. Carpenter

A program of scaled flow model experiments has been undertaken to study the performance of five-spot water floods. The modeling procedures are discussed and the construction and operation of the flow models are described. The tests were specifically designed to investigate the effects of injection rate and of oil-to-water viscosity ratio on oil recovery. The areal sweep of five-spot water floods was also studied, and direct comparisons between five-spot and linear flooding behavior have been established to permir better utilizatfon of core analysis results for purposes of field waterflood evaluations. INTRODUCTION For a long time reservoir engineering procedures have been confined to the consideration of idealized, one-dimensional or linear systems.11* However, direct application of the linear waterflood mechanism to the evaluation of actual field performance is justifiable only for the purposes of rough approximation. To obtain a realistic analysis of field behavior, it is necessary to account for reservoir geometry and well distribution, and to take into consideration the configuration of the flow of fluids between injection and producing wells. In the past it has been attempted to account for the complex nature of the fluid movement in the reservoir by associating each well pattern with a certain "sweep-efficiency constant", e.g., a sweep efficiency of 72 per cent for the conventional five-spot pattern.' More recently, methods of waterflood evaluation have been improved by the introduction of variable sweep-efficiency factors, defining the areal coverage as a function of cumulative water injection and viscosity or "mobility" ' ratio.""' These variable sweep-efficiency factors, derived from miscible fluid displacement experiments, require the assumption of piston-like displacement of oil by water. This implies that only one fluid, either oil or water, is moving at any one point of the reservoir ht any moment. Such an assumption, however, is incompatible with the bulk of the experimental evidence and also theoretical considerations which indicate that usually in the area invaded by water, both oil and water are flowing in varying proportions, in accordance with the relative permeability characteristics of the porous medium. Another recent approach toward the evaluation of five-spot flooding behavior involves correlations of the areal sweep efficiency (observed in immiscible fluid experiments) with a "mobility ratio," based on the consideration of the "average" relative permeability to the displacing fluid. Combination of these correlations with a modification of the Buckley-Leverett frontal-drive equation leads to a computational procedure for predicting the recovery performance of areal water floods. While of considerable interest, this approach has no complete theoretical justification and, therefore, does not entirely clarify the features of five-spot water floods. Rigorous, theoretical treatment of waterflood behavior in two- or three-dimensional systems as encountered in the reservoir, including proper consideration of relative permeability and capillary-pressure functions, is as yet beyond the scope of analytical or computational methods. The, behavior of such water floods can, however, be studied by means of scaled flow model ekperiments, which is the approach followed in these investigations. The flow model experiments described in this paper simulate a uniform, horizontal formation of constant thickness with fully penetrating wells. The system under consideration is entirely liquid saturated and not influenced by compressibility effects, which is representative of the situation achieved after gas fill-up under practical conditions. Gravity segregation effects are assumed to be negligible, which implies a relatively thin reservoir formation and/or low vertical permeability. THEORETICAL CONSIDERATIONS For a flow system of uniform thickness with no appreciable effects of gravity segregation, the analysis of water-oil displacement can be confined to a two-dimensional treatment based on the consideration of a "slice" of unit thickness. Referring to previously established derivations," the displacement of oil by water in such a system can be described by the following, dimen-sionless equations:

By W. S. Sanner

Experiments were conducted to determine the quantity and purity of ultraclean anthracite that could be prepared in the laboratory, using conventional separating techniques. A low, a medium, and a high-volatile anthracite were studied. Specific gravity separation followed by grinding, screening, and refloating at lighter specific gravities yielded small quantities of material purified to 1.0% ash, as follows: from low-volatile anthracite, 0.7%; from medium-volatile coal, 1.0%; and from high-volatile coal, 2.3%. The reduction in ash had no appreciable effect on the volatile matter or sulfur content of the coal. The limited quantities of material containing 1.0% or less ash obtainable indicate that if ultraclean coal is desired, a practical approach should include the processing units as an integral part of a convc.ntiona1 dense-media washing plant. Anthracite preparation practices during much of the industry's history were geared to maximum recovery of the larger sizes, pea through egg, which were used in hand-fired, domestic furnaces. Those sizes were cleaned to meet trade requirements, and the smaller sizes were usually higher in ash content. The impression, thus, was that ash content of anthracite always increased as the sizes got smaller. It was presumed that it was impossible to wash the finer sizes to extremely low ash contents. Following World War 11, the classical domestic market began to decline and the finer sizes assumed an increasingly large share of the market. For example, in 1949l 61% of the production was still pea and larger. Fig. l2 shows that -by 1955 these sizes accounted for only 50%, and in 1965, they were only 39% of the total anthracite produced. With the reduction in the market, increased quality was demanded, especially in export markets, and an increasing number of dense-media magnetite washers were installed in new and existing cleaning plants. In 1965, the coarse coal prepared at 59 breakers in the anthracite fields was sampled by the U.S. Bureau of Mines (USBM); approximately 50% of these plants were equipped with dense-media magnetite washers.3 Since 1950, more attention has been focused on the use of finer sizes for numerous industrial uses, including iron-ore sintering, pelletizing, foundry coke-making, cement manufacture, production of calcium carbide, and of carbon electrodes, etc. Most industrial uses require relatively clean anthracite, such as 10 to 11% ash for sintering and foundry coke, 7% for aluminum melting-pot cathode carbon, and 5% for carbide production. Hence, cleaning methods have been improved to the extent that dense-media washers, hydraulic cyclones, and flotation cells have been introduced as fine-coal-cleaning devices. It is now possible to wash the buckwheat, rice, and barley sizes (9116 X 3132-in.) to ash contents as low as 8 to 10% in dense-media devices, but washing the -3132-in. sizes to those limits presents more difficult problems, due mainly to the fineness of the material. This USBM investigation was conducted to determine the amount and purity of ultraclean anthracite that could be prepared in the laboratory, using conventional separating techniques. The goal was to reduce the ash content to a level acceptable for industrial carbon uses, including electrode manufacture, which generally requires an ash content of 1% or less. While low-ash content is of primary importance in selecting industrial carbons, the amounts of other constituents are also important, including iron, silicon, titanium, nickel, vanadium, and sulfur. They were not considered in this work, since their occurrence in deashed anthracite has been studied elsewhere.4 The results of the present investigation were used to design a flowsheet, suggesting a method for producing ultraclean anthracite as part of conventional preparation practice, using dense-media vessels, crushers, pulverizers,

Jan 1, 1970

By Christina V. White

An experimental study was undertaken to investigate the feasibility of utilizing vapor transport for the treatment of heavy metal contaminated smelter soils. The focus of this project was to develop process chemistries that would make incineration a viable process for the treatment these soils. The experimentation concentrated on the elimination of arsenic, cadmium, and lead, and was performed in a laboramry scale rotary kiln setup. Three soil samples from non¬ferrous smelter sites, which contained various concentrations of contaminants, were utilized in the experimentation. Three chemistries were investigated for the volatilization of the heavy metals: Chloridizing volatilization, ferric chloride vapor complex formation, and the use of oxygen potential control. The samples were analyzed for residual heavy metals so that the extractions could be determined. However, the ultimate test was the leachability of the residual arsenic, cadmium, and lead, as determined by the TCLP test. The results firmly establish that incineration is a feasible process for the treatment of metal contaminated soils. It was found that no one process chemistry is suitable for all different soil samples. A two-step process consisting of a reducing step followed by a hydro-chlorination step was required to make Soil Sample-B pass the TCLP tests for all three heavy metals. Soil Sample-A passed the TCLP tests for arsenic, cadmium, and lead using a hydro-chlorination process at a minimum temperature of 700°C. In addition to passing the TCLP mm for Soil Sample-A and Soil Sample-B, 70 to 80 percent removal of the impurities was accomplished. This demonstrates that the leachability of the impurities was decreased primarily due to the removal of a large fraction of the contaminants, Soil Sample-C possessed very high levels of cadmium and lead and only moderate extractions of the impurities were generated from this soil. The arsenic TCLP test was passed at 500'C using a process gas containing ferric chloride and at temperatures of 700°C and above using chlorination of hydro-chlorination.

Jan 1, 1996

By D. R. Tesarik

Researchers from the National Institute for Occupational Safety and Health (NIOSH)1 and engineers from Placer Dome, Inc.2, conducted an underground rockfill span test at the Turquoise Ridge Mine near Golconda, Nevada, USA with the purpose of improving safety and increasing productivity by using a bulk mining method instead of drift and fill. A rockfill sill was constructed by mining and backfilling six adjacent, parallel drifts and then undercutting the sill with a 13.7 m (45 ft) wide and 30.5 m (100 ft) long room. Displacement measurements from vertical borehole extensometers installed in the mine roof and rockfill indicated that the sill remained stable with a maximum vertical deformation of less than 5 mm (0.2 in). These results were confirmed by visual observations and calculations from a validated three-dimensional numeric model of the sill. The numeric model was also used to simulate load on the sill produced by dislodged roof material in the shape of a 11.0 m- (36 ft-) high triangular prism with base measurements equal to those of the sill. Failure in the bottom third of the sill occurred with this additional load.

May 1, 2007

By Lynn B. Hales

Unfortunately, the term "control" has a negative connotation in the minds of many of our operating plant personnel. Whereas the opposite is true of those associated with research and technical centers in our industry. The magnitude of this difference in opinion and actual experience has often proved to be a major factor influencing the success or failure of process control applications. Through the years, many plant people have endured a number of unsuccessful attempts by "outside" people to "optimize" their plants; and these experiences have proved to have had quite a callousing effect on them. On the other hand, in many plants, successful process control efforts have made firm allies of the operating personnel, and have increased the number of metallurgical people who are well qualified and experienced in process control. The instrumentation industry, computer industry, and the mining industry's ability to quantify what is really happening in our processes have grown and developed rapidly since the first control efforts were made in the 1930's (1). Because of this-,: new control opportunities are becoming increasingly more feasible and older well established ones are becoming even more practical and necessary with regard to the economic s of our industry.

Jan 1, 1979

By J. J. Dekker

Controlling noise has proven difficult in mining, and noise-induced hearing loss (NIHL) remains common. In 2008, a South African Mine Health and Safety Council study focused on small- to medium-sized mines in relation to the milestones set by the industry to prevent NIHL. An evaluation of the compliance of ten diamond, sand, aggregate and Ready mix concrete mines and production sites with standards, legislation and best practice guidelines relating to NIHL prevention was conducted, using a noise compliance audit tool. The findings indicated that all mines surveyed had poor compliance with the international standards, compliance with International Standards Organization standards being the poorest. There was a clear distinction between the small and the medium-sized mines in their compliance with local standards and legislation (ranging from 14 per cent to 66 per cent). The areas of best compliance were audiology and medical examinations. The lower-than-expected compliance was largely attributable to shortcomings in hearing conservation programmes for occupational noise. Initiation of remedial practices in the small- to medium-scale mining sector to facilitate improvements in NIHL prevention and compliance with standards and legislation is recommended. Keywords Hearing conservation, small-to-medium mines.

Jan 1, 2011

By Randall J. Weege

Nickel laterites throughout the world are similar in their gross aspects, but vary significantly in detail. The deposits occur in two separate and distinct geologic settings --those formed over ultramafic rocks which were mechanically emplaced, and those formed over ultramafic rocks that were intruded as melts. The source of the primary nickel in the parent rock may occur both as ionic replacement in silicate lattices and as nickel sulfides. Factors controlling the degree of laterization and nickel enrichment are dependent upon the parent rock characteristics as well as chemical and climatic conditions. Two chemically and physically distinct zones (oxide and saprolite) are commonly present in the laterized rock, but one or the other may be extremely thin or absent. Cobalt and copper may be present in recoverable amounts. Geologic, geophysical and geochemical methods are all utilized in exploring for these deposits. These methods are compared, evaluated and illustrated in the paper. Drilling patterns and ore reserve calculations are also discussed. In contrast to many ore deposits, processing costs are much higher than mining costs. The most efficient processing method is directly dependent upon the chemical composition of the ore. This variation in the chemical and physical characteristics of nickel laterites requires a detailed test program of the metallurgical response to representative samples and blends of ore. Detailed laboratory and bench-scale metallurgical tests are necessary prior to a full scale pilot plant test.

Jan 1, 1978

By L. Ou

This paper reports on research on leaching pyrite in a germ-free system. The effects of mineral particle size, pulp potential and various oxidation agents on pyrite leaching were studied. The results indicated that a smaller mineral particle size leads to a higher leaching rate of pyrite. The optimum results were obtained with a mineral particle size of -0.037 mm. The pulp potential reflected the leaching process and an increasing pulp potential improved pyrite leaching. The leaching rate rapidly increased with the addition of oxidation agents such as Fe3+ and H2O2. However, the precipitate generated by ferric ion coated the surface of the pyrite and prevented further leaching.

Jan 1, 2007

By M. A. Trevits, J. E. Urosek, A. C. Smith, M. P. Valoski

Unlike other types of mining accidents, where an incident generally involves only a few workers, the danger of a mine fire extends to every person working in the underground environment. Mine fires can trap or kill those working underground by blocking avenues of escape and rapidly creating heat, asphyxiating gases and toxic fire products that can quickly spread throughout the mine. The National Institute for Occupational Safety and Health (NIOSH), in partnership with the Mine Safety and Health Administration (MSHA), is conducting research to test, evaluate and improve or modify coal mine fire-fighting strategies and methodologies through large-scale tests. Because wood is the second most abundant fuel available during a coal mine fire, it was decided that a series of large-scale wood crib fire tests was needed to measure the products of combustion and to observe the capability of commonly available direct application fire suppression equipment, namely, fire extinguishers, water and gas-enhanced foam. This paper discusses the wood crib fire tests, provides insight into the products of combustion and describes observations made during the application of the fire suppression agents.1

By Charles Hardy, George D. Cremer

POWDER metallurgy has been established for some time as a novel method for manufacturing a great variety of articles generally specialties that could not be made conveniently by any other method. In this category are such parts as porous hearings cutting tools of sintered carbides, and electrical contacts in which the metallic constituents do not tend to alloy in the proportions employed. The industry, however, is now at a stage where it has begun to manufacture articles that can and have been made by other methods. Thus, powder metallurgy is now preferred technique for the production of numerous machine parts characterized by high strength, accuracy of configuration, and substantial lack of porosity. Manufacture of such machine parts from metal powders has no doubt been stimulated by the war, although the trend in this direction has been apparent for several years. In any case, quantity production of high-density precision pieces by ponder metallurgy is now in full suing in the United States, and such production can and should continue to expand during and after the war.

Jan 1, 1942

By S. R. Hutchins

Several refractory sulfide and carbonaceous gold ores were examined to determine whether microbial pretreatment could be used to enhance gold recovery. Test samples were biologically leached using unique, thermophilic microorganisms to solubilize iron sulfide minerals. Gold recovery from sulfide ores and concentrates was enhanced following pretreatment with the thermophiles; responses varied widely for the individual materials. Although bioleaching had little effect on the preg robbing characteristics of the carbonaceous gold ores, cyanidation of the bioleached residues yielded higher gold recoveries than cyanidation of the native ore. By combining bioleaching with abiotic processes designed to inhibit preg robbing, gold recoveries of 83-98% were obtained from carbonaceous ores yielding 10-50% gold recovery by direct cyanidation.

Jan 1, 1987

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970?s, only the sub-aeration mechanical cells were dominant. Since the 1980?s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs.INTRODUCTIONFlotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. Froth flotation started in Australia at the beginning of the 20th century and since then flotation technology has made significant advances. Flotation was firstly applied to sulfide ores. The largest tonnages treated by flotation are copper and copper/molybdenum ores, handling about 50% of the total ore processed. Also significant are phosphate, iron ore and coal treatments. At present, Chile is the foremost copper producer in the world with around 35% of the world?s production. Figure 1(a) shows the evolution of copper production in Chile over the last decade. The total amount of fine copper produced in year 2001 was 4.7 million tons, from which 3.2 million tons was processed by flotation while 1.5 million tons went through LIX-SX-EW processes, which also showed significant development during the same period (Anon, 2001). The total flotation treatment of copper ores in Chile is about 325 million tons per year (Anon, 2002), so the world treatment of copper ore by flotation can be estimated at about 1 billion tons per year. Consequently a total of nearly 2 billion tons of ore per year is presently processed worldwide by flotation (Fuerstenau, 2001). In order to handle the higher tonnage of low-grade ore, a worldwide trend towards the development and use of larger flotation machines began in the 1960?s. Figure 1(b) shows that the trend became extremely marked from the beginning of the 1990?s, which is consistent with the strong increase in copper production during the same period."

Jan 1, 2003

By IPMI Educational and Scientific Foundation

It is with great pleasure that we announce the availability of this fifth issue of the IPMI Journal, a publication of the International Precious Metals Educational and Scientific Foundation. This digital peer reviewed publication has been created as a vehicle for the sharing of technical information related to the science and technology of precious metals. Since 1976, the International Precious Metals Institute has championed the exchange of information of critical importance to the precious metals scientific and commercial communities through its various communications vehicles. This has included instructional videos, annual conference symposia, special topic committee meetings, regional seminars, and professional and student achievement awards. Due to the breadth of important topics related to all aspects of precious metals, it has been the vision of the IPMI to provide a publication available to the general public that would become a key source of pertinent topics containing high quality publications by experts in their fields of study. Historically, the IPMI has attracted world renowned experts in many fields (including Nobel Laureates Henry Taube, Ei-ishi Negishi, Robert Grubs, Professor Ben Feringa, and David MacMillan) in the dissemination of discoveries, inventions, and industry proven practices. Such information has a total value greater than the sum of its parts as seemingly unrelated innovations from distinct focus areas can be adapted to solve problems. Because of this important characteristic of information exchange, we have decided to create a digital journal, available to the general public, that will not only communicate state of the art discoveries and sound practices, but will also review historical communications from the IPMI’s archives that have value and use even in today’s environment.

Dec 1, 2024