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By S. J. Kidder

The Mogollon mining district is in the southwestern part of New Mexico near the southern end of the Mogollon range, from which the district takes its name. The town of Mogollon is but 371/2 miles in an air line northeast of Clifton, Ariz. The air-line distance from Silver City is 521/2 miles and from Tyrone, 57 miles. Supplies are transported by motor truck from Silver City. The distance by road is 75 miles, half of which is an improved highway of modern construction. Transportation has always been a large item of expense in carrying on operations in the district. Valuable ore is said to have been discovered in the Mogollon Mountains as early as 1870 but the first regular prospecting was carried on in 1875, by James C. Cooney, a sergeant from Fort Bayard. His discovery of rich silver-copper ores in the region of Mineral Creek led to the establishment of the Camp of Cooney. Remote from any settlements where there was a semblance of law and order, and harassed by the Apaches, development was slow and nearly 10 years elapsed before the village of Mogollon was established on Silver Creek. Prospecting in this section of the district had disclosed the outcrops of several promising veins containing silver-gold ores. Among the early claims located were the Last Chance, Top and Confidence, on what has proved to be the most productive vcin in the district. To the end of 1922, the Last Chance and Top claims had produced approximately 600,000 tons of ore and nearly 200,000 tons had come from the Confidence group of claims. The total value of the ore produced from this vein alone has amounted to about $9,600,000 in silver and gold. The Fanney vein was developed later and during its most active period of production contributed more than half of the output of the district. Other important locations, though far less productive than the above, were the Maude S, Deep Down, the Deadwood and the Pacific.

Jan 1, 1925

By N. S. Keith

No one of the live subjects of the day, to which the attention of the mining engineer and metallurgist should be turned, is of greater practical interest to him than electricity in its applications to various mechanical, chemical, and metallurgical operations. The object of this paper is to call the attention of my fellow-members and associates of the Institute to various new, as well as comparatively old, developments in the science and art of electricity which seem to promise results of advantage. Too many of the comparatively old applications have been neglected by the mining engineer, which; if he had given them a place among his appliances, would have assisted him greatly. The telegraph may be noticed as one. Its. use is, however, confined to a person having skill in the. manipulations of the key, the reading of the alphabet, and familiarity with the sounder. One of the simpler forms-the call-bell-has a range of application far greater as to distance and convenience than the old wire-pull, or the hoarse voice of the windlass-man or the bucket-dumper. A few Leclanehé cells, two or more electric bells, and a mile or more of wire judiciously placed will put the superintendent, at his office, in communication with the foremen of his mills and mines, so that by the aid of a code of signals, great advantages may be gained without necessitating a knowledge of the Morse alphabet, or of the mechanical voice of the sounder. The telephone furnishes a means of communication be-

Jan 1, 1882

By Y. Kondo, A. M. Gaudin

A combined method for sizing in the sub-micron range was developed using centrifugation and gamma emission. Its essential features are: 1) Centrifugation of suspended mineral in water carried out at 4°C where water has its maximal density and zero temperature gradient of density 2) Gamma activition of the sample suspension induced by irradiating it in a nuclear reactor prior to centrifugation 3) Measurement of the activity of a beam of suspension as it is sedimenting in the centrifuge, using a scintillation counter provided with a discriminator. Albite, the sodium feldspar, was used as feed to the comminution step, and the induced gamma activity of Na24 was measured. Dissolved sodium ion caused a a non-settling activity in the measurement. Other "noise" is due to scattered gamma radiation from albite particles in the centrifuge outside of the line of sight. These two activities were obtained sep arately and subtracted from the total activity counted. The relative solid concentration in the suspension under the collimating slit is proportional to this net activity. The cumulative weight per cent of undersize particles was calculated and plotted against size on logarithmic scales. The relationship was found to be linear down to about 30 mµ. The specific surfaces calculated from particle size distribution agree with those measured by krypton gas adsorption. The measurement of particle size distribution of comminution products has been of interest in clarifying the mechanism of the process. The Gaudin-Schuhmann equation1,2 relates the cumulative percentage undersize, y, to relative particle size x/k. The particle size, x, and the size modulus, k, together with the distribution modulus, m, characterize the particle size distribution, m is the slope of a plot of log (y) against log (x/k). This equation has been verified for ground particles down to 1 micron in size.3'4 For particle sizes smaller than a few microns, the precision and facility of sedimentation and microscope techniques become questionable. Use of a centrifuge which shortens settling time from weeks to hours is attractive. Many centrifugal methods have been proposed; however, determination of the solid concentration of the suspension at a reference level as a function of time is difficult, and sampling the suspension is likely to introduce errors. Measurement of particle size distribution by X-ray absorption in gravitational5 and in centrifugal6 sedimentation have also been tried. In these methods, the absorption coefficient for the solid is independent of size, since the wave lengths of the X-rays and gamma-rays are orders of magnitude smaller than the particles. Radiometric techniques7 in size distribution measurement have been developed within the last several years. They offer advantages over usual gravimetric and optical methods. PRINCIPLE OF METHOD The combined method of centrifugation and gamma emission for sizing in submicron range described in the present paper has the following essential features. 1) Centrifugation is carried out at 4 ± 0.1°C. Convection currents in the water phase due to density changes caused by temperature variation may disturb completely the settling system. To avoid this difficulty, the unique property of water having zero temperature gradient of density at 4°C is used. 2) Prior to size measurement the sample suspension is irradiated in a nuclear reactor and gamma activity induced. The gamma activity of the particles sedi-mented radially is measured by a scintillation counter provided with a discriminator. By this method, interruption of centrifugation by withdrawing samples is avoided and the counting rate at any time represents the solid concentration in the suspension at the level of the collimating slit of the centrifuge at the particular time at which the measurement is made. 3) By proper selection of the feed material and of the comminution device, gamma activities of foreign

Jan 1, 1964

By J-S. Marois, F. Cappucitti, Y. Dodier, D. Downey, G. Matton

"The flotation processes of the Niobec Mine have been affected by a seasonal loss of recovery and a significant increase in reagent consumption over the past few winters. This paper discusses the problem-solving methodology that was used to identify the root causes, to develop solutions and to implement changes that resolved the problem to restore the process to summer-like conditions year-round. Mainly, it was found that the process water was contaminated by phosphates ions, which adversely affected the carbonate pre-flotation, and caused detrimental effects on the subsequent niobium flotation. The phosphate ions were being generated by the process itself, but were consumed by algae in summer conditions. It was determined in laboratory studies that concentrations as low as 5 ppm were enough to affect the circuit and that the multiple additions of process water throughout the circuit was worsening the effect. Also, temperature was found to have an impact on the reagent performance. The performance of the plant was restored by implementing a natural treatment of our process water with a simple cost-free rearrangement of our circuit streams. In addition to that, our extensive geometallurgical program was used to provide ore to the plant restricting phosphate generation in the process. Also, a modification of the collector was developed and introduced in the carbonate pre-flotation that provided improved performance during the periods of low pulp temperature.INTRODUCTION Niobec is one the three major global producers of niobium presently in operation. Situated in the Saguenay-Lac-St-Jean region of Quebec and in operation since 1976, the site produces ferroniobium (FeNb) to be used mainly in High Strength Low Alloy (HSLA) steel, which is known to have better mechanical properties than carbon steel. The Niobec operation consists of an underground mine, a concentrator and a converter plant. The concentrator concentrates niobium-bearing minerals, mainly pyrochlore and columbite, to produce a high-content Nb2O5 concentrate which is then converted to FeNb in the converter plant by an aluminothermic reaction. The Niobec concentrator flowsheet, which has gone through many expansions and optimisation over the years, consists of grinding, desliming, flotation and leaching steps. The flotation steps are numerous, sensitive and difficult to operate due to the non-selective nature of oxide mineral collectors. Thus, the pyrochlore concentration process at Niobec still faces many challenges and is constantly going through periods of continuous improvement."

Jan 1, 2018

By R. Neilson Clark

THE coal-beds of Canyon City are situated six miles below the town, upon the Arkansas River. At this point the Rocky Mountains have thrown out from their main ridge two spurs. The one to the north, containing Pike's Peak and Cheyenne Mountain, is known as part of the "Rim Range;" the one to the west and south is known as the "Greenhorn Range." Against these syenitic mountains, the later rocks are piled and uplifted ; at right angles to the direction of this main uplift is the axis of a lesser plication. On the north, west, and south, the pitch is steep, gradually flattening as it approaches the centre of the basin and rising again to the east at a pitch of about 5", thus forming a perfect basin, the centre of which is only three miles east of the base of the Greenhorn Range.

By A. C. Fieldner, W. A. Selvig

Information concerning the fusibility of coal ash has become of considerable value to the consumer of coal, mainly in connection with the troublesome formation of clinker resulting from the melting of the ash constituents of the burning coal. The growing interest in such data has led the Bureau of Mines to make a general survey of the "fusing" or "softening" temperatures of the ash from coals of the United States. It is hoped that this information when used together with the large number of coal analyses published 1 by the bureau will assist the consumer of coal in comparing different coals, and in selecting the coal best adapted for his purpose.

Jan 1, 1922

By Horace C. Porter

Much has been written of the changes undergone by coal in storage and the deterioration of coal through exposure to the weather. In order to obtain definite information for the benefit of the Government departments and of all who store coal in large quantities, a series of tests was begun in the fall of 1909 under the supervision of J. A. Holmes, then chief technologist of the United States Geological Survey, and was continued by the Bureau of Mines after its establishment in 1910. The tests were confined to determinations of the loss in heating value of the coals and did not include a study of other deterioration; for example, in coking quality or the yield of by-products in coking. The Bureau of Yards and Docks of the Navy Department cooperated in tests of New River (W. Va.) coal, a variety largely used by the Navy. A preliminary report presenting a brief account of the early results of these tests has been published by the Bureau of Mines as Technical Paper 16.a The detailed report is presented in this bulletin, which gives a full account of the tests and the analytical data covering a period of five years' storage. Data of somewhat similar experiments for shorter periods with gas coal from the Pittsburgh bed, with Pocahontas coal on the Isthmus of Panama, and with Sheridan, Wyo., subbituminous coal, which is used for railroad and other purposes in the West, are included.

Jan 1, 1917

By S. J. Rothman, J. J. Hines, D. Rokop, R. Bastar

Self-diffusion has been measured along each principal axis of mosaic-structured and relatively perfect a uvaniuln single crystals. The anisotropy reported before,' D[loo] = D[001] » D[010 , has been confirmed. and is shown to represent volume diffusion. Diffusion along the dislocations in the imperfect crystals increases the measured value of D significantly without changingr either the shapes of the penetvation plots or the anisotropy. SINCE a uranium is orthorhombic, the diffusion coefficients along the principal crystallographic axes need not be equal. A previous measurement of self-diffusion in three mosaic-structured a uranium single crystals1 showed that Dil00| =D[001 >>D[010 This result was deduced from penetration plots similar to those in Fig. 1. That is, the plots for diffusion along [loo] and [001] were the straight lines expected from the solution of the diffusion equation for the boundary and initial conditions of the experiment, while the plot for diffusion along [010] was curved so that the part near X = 0 had a much steeper slope than the straight lines did. The observed anisotropy could have been due either to volume diffusion or to diffusion along the very large number of dislocations in such crystals, according to the model proposed by aart.' The authors of Ref. 1 argued that the latter possibility was unlikely, but did not exclude it. To settle the question, a simultaneous measurement of self-diffusion in mosaic-structured and mosaic-free crystals was carried out. This paper reports the results, as well as a measurement of the temperature dependence of self-diffusion in a uranium. EXPERIMENTAL The single crystals of a uranium used in this experiment are listed in Table I, together with other experimental details. '(Mosaic structured" here means crystals grown by solid-state phase change.3 The Laue spots from such crystals spread over about 6 deg of arc, which indicates that the density of dislocations is very large. "Perfect" crystals are ones grown by Fisher's grain-coarsening tehnique; the Laue spots from these are quite sharp,4 which shows that the dislocation density in these crystals is much lower. All of the crystals were made from high-purity uranium; a typical analysis is given in Ref. 1. The actual diffusion directions were within a few degrees of the nominal. The thin layer-sectioning method was used. The experimental techniques were similar to those described in Ref. 1, except the sectioning. Crystals Za, 2b, 2c, 4a, 4b, and 4c were sectioned on a lathe. Crystals 3a, 3b, and 3c were sectioned by grinding on glass plates, with 1 p diamond powder in butyl alcohol as the abrasive. The use of glass plates eliminated the crowning noted in Ref. 1, and the use of butyl alcohol as a lubricant simplified the chemical processing of the sections. Material from the sides of these three crystals was removed by spark machining before sectioning. The sectioning of crystals 4a and 4c was botched. A small cylinder of metal was extruded from the center of crystal 4a while turning off material from the side of the sample. Crystal 4c was misaligned by 2.1 x 10"3 cm because the dial gage jammed during the alignment. Notwithstanding these errors, useful data were still obtained from these crystals. The points

Jan 1, 1967

By Samuel B. Christy

" The man is always greater than his work." The training of the men who are to develop the mineral resources of the world is the most important problem connected with mining engineering. It becomes ever more important to civilization as the mineral wealth of the earth approaches exhaustion. I have therefore decided to consider a few of the more important problems arising in the training of the mining engineer, and especially those arising in America. , The Peculiar Nature of Mineral Wealth. Mining and Agriculture are the two fundamental arts. Without the latter our existence would be precarious; without the former, our civilization impossible. Agriculture furnishes that regular supply of food and raiment which leads to the growth of large communities in which cultivated leisure first becomes possible; while mining furnishes the metallic thread from which is woven that complex fabric we call civilization. But in these two arts the conditions for success are widely different. Most of the crops that the farmer reaps may be harvested year after year, and the proper fertilizers being added, he may continue the annual harvest indefinitely, while, as a result of cultivation, his farm becomes yearly more valuable. But the crop the miner reaps can be harvested but once in the history of the race. Our mineral wealth has taken unknown ages to mature in the bosom of the earth. The ripened fruit can be plucked but once. There are no fertilizers for worked-out mines. It never pays to work over a mine that has been

Jan 1, 1906

By A. C. Fieldner

THE COMMITTEE on Correlation of Research held two meetings in 1931. The first was a luncheon meeting on Feb. 19, at the Engineers Club, New York, attended by eight members and four guests-William H. Bassett, past-president of the Institute; Robert E. Tally, president; H. Foster Bain, secretary; and Alfred D. Flinn, director of the Engineering Foundation. Mr. Bassett gave a short resume of the circumstances leading to the formation of the Committee and expressed his opinion that the objectives as expressed by the Committee in its first annual report were in accordance with the ideas of the Institute officials. Mr. Tally stressed the great importance of research in the mining and metallurgical industries and stated that lie believed the Institute should encourage and promote research, and that this Committee could do a great deal to foster such work in the Institute. Mr. Bain pointed out that this Committee was appointed with a view to correlating and fostering research work. in the field of the Institute's activities. This could be done in various ways, as by encouraging the divisions and committees of the Institute to hold group meetings on research, by forming research subcommittees in the Institute divisions, and by bringing together research interest in. certain projects and the fund or organization that is equipped to carry out the project.

Jan 1, 1932

By Jas. E. Thomson

PUBLIC attention was first attracted to the Crow River area of north-western Ontario by the discovery of gold in 1928. The first three discoveries were eventually developed into Central Patricia, Pickle Crow, and Albany River mines. In 1929, preliminary developments were carried out at the Howell vein on N.A.M.E. (later Pickle Crow) claims, and in 1929 and 1930 surface and underground work indicated an ore-body at Central Patricia mine. However, due to the financial depression and the distance of these properties from the railway, it was not until 1934 and 1935 that, benefitted by the revaluation of gold, the real potentialities of these two properties began to be realized. Their immediate success led to a resumption of activity on neighbouring properties throughout the area in 1936 and 1937. Preliminary prospecting in the earlier period had been limited by the scarcity of rock exposures in the country. The procedure in the recent programme of intensive exploration has been along similar lines at most properties and has consisted lf detailed geological mapping accompanied by geophysical surveys and followed by systematic drilling of favourable zones. The present importance of the camp may be judged by the fact that, in 1937, Central Patricia and Pickle Crow mines together produced bullion valued at $3,662,953, and paid $1,450,000 in dividends. In addition, there were pro-mising gold developments at Albany River mine. During the past two seasons, the Geological Branch of the Ontario Department of Mines has been making a fairly detailed study of the geology and mineral deposits in the Crow River area. It is the purpose of this paper to present a brief statement of some of the structural features of these deposits; a summary of other geological information essential for the understanding of the main topic is included. A more detailed report on the area will be published shortly by the Ontario Department of Mines. It is impossible to make full acknowledgment here for all help received, for the writer is in-debted to the management, staff, and consultants of every Company in the camp for generous co-operation in the field and for information, plans, maps, and records placed at his disposal. Reports and articles on properties in the area have been written by Hurst (1), Cormie (2), Reid (3), and the staff of Pickle Crow Gold Mines ( 4).

Jan 1, 1938

By AIME AIME

The Institute Headquarters at Spokane was established at the Spokane Hotel, and included a Bureau of Information for the benefit and comfort of members and guests of the party during the time of the meeting. The first session, held Tuesday afternoon, Sept. 28, 1909, in the beautiful Convention Hall ,of Masonic Temple, was called to order by Mr. E. J. Roberts, Chairman of the Spokane Local Committee, who introduced Mr. J. C. Ralston, City Engineer, representing the Mayor of Spokane and the Spokane Chamber of Commerce. Mr. Ralston extended to the members and guests of the Institute a cordial welcome to the city of Spokane, substantially as follows:

Dec 1, 1909

By D. H. Rousell

"Rocks of the Whitewater Group (Aphebian age) oc ithin the Sudbury Basin and consist of three formations rre, from oldest to youngest: Onaping, heterolithic breccias lus an igneous-textured component; Onwatin, argillite and siltstone; and Chelmsford, greywacke with minor argillite with siltstone. Mineralization in these rocks is as follows:1) Sulphides are disseminated throughout the Onaping Formation. Pyrrhotite, the major sulphide mineral, occurs mainly as fragments; other sulphides are chalcopyrite, sphalerite, galena, pyrite and marcasite.2) Zn, Pb, Cu, Ag and A u mineralization in the Vermilion member, a carbonate-chert unit near the base of the Onwatin Formation (Vermilion and Errington mines).3) Pyrite and minor base metals in the Onwatin Formation .4) Mineralized quartz veins, located at or near the base of the Onaping Formation, include such deposits as Moore Lake (Pb, Zn and Ag), Foisey (Zn, Pb), Papineau (Cu, Au and Co) and Proulx (Pb, Zn, and Cu). Quartz-carbonate veins in a meta-gabbro sill contain Cu, Zn, As and Au. Material from quartz veins from two former ""gold mines"" (Gordon Lake and Creighton) yielded no Au values.5) Anthraxolite veins in the Onwatin Formation .The mineral occurrences can be explained in term of either the volcanic theory or meteorite-impact theory of basin formation. According to the latter theory, the sulphide fragments in the Onaping Formation may have been formed by the brecciation of sulphide-rich pods located in the upper mantle and at the base of the transient crater; some of the sulphides may have been derived from target rocks of the Huronian Supergroup. The Vermillion-Errington deposits may represent sedimentary exhalative deposits of the Remac type; mineral-rich brines, trapped at the base of the transient crater, rose upward and precipitated the mineralized carbonate-chert under reducing conditions. These conditions continued throughout the deposition of the upper Onwatin Formation but pyrite was the only sulphide that formed.The quartz veins were emplaced during the time of basin deformation. Metamorphism remobilized and concentrated carbonaceous material in the Onwatin Formation 10 form the anthraxolite veins."

Jan 1, 1984

By R. H. Sheaphim

THE RECENT and continuing activity in the Boundary district, British Columbia, makes the publication of this paper timely. The following description and discussions are based on two years' experience in the district as Field Manager and Geologist for Attwood Copper Mines, Limited. The Attwood project was organized by Dr. D. F. Kidd to re-examine the Boundary mining camp. Thanks are due to Dr. Kidd, both for his intelligent guidance during the project and for his permission to publish this paper. Much of the data and many of the interpretations presented are credited to the work of, and to discussion with, Dr. W. H. White, Consultant Geologist, who worked for two field seasons on the project. However, the author assumes the responsibility for this presentation. Dr. C. D. A. Dahlstrom worked with the author during the latter stages of the project. His assistance and advice are gratefully acknowledged.

Jan 1, 1956

By B. Kruger

The Dundee Precious Metals Tsumeb Smelter has evolved over the last decade to meet the challenges and opportunities brought about by a changing copper concentrate market, technological advances, environmental legislation as well as social and political changes. The paper discusses some of the challenges, successes and lessons learnt through the expansion and modernization of its smelter complex. It considers the details and impact of the transition from slag granulation to that of slag slow cooling as well as the improvement program that was implemented to more than double the refractory campaign life of the Ausmelt furnace from around 6–9 months to 15–18 months. In addition, given the evolving world we live in, it considers the challenges that the smelter faces today, not the least of it being how to remain relevant in an age of digital and other 4th Industrial Revolution disruptions. INTRODUCTION Dundee Precious Metals Tsumeb (DPMT) Smelter is located just outside the town of Tsumeb, in the Oshikoto region of Namibia. It is the largest town in the region with a population of approximately 45,000. The smelter was built in the early 1960s to treat concentrate from the nearby Tsumeb copper mines. Construction of the site was completed in 1962 and the smelter was officially commissioned in 1963 by Tsumeb Corporation Limited (TCL). At the time the smelter consisted of a lead section (including a refinery), a copper section and plants that produced cadmium, sodium antimonite and arsenic trioxide. Production commenced in early 1964, with 3,500 tonnes of copper and 6,000 tonnes of lead being produced per month. TCL was acquired by Gold Fields South Africa in 1988, and a few years later the lead section was shut down due to reduced lead content of the mined ore. In mid-1996, all mining and smelting operations were halted due to labour strikes. Ongopolo Mining and Processing Limited (OMPL) re-opened the mines and the smelter in 2000, only operating the copper section of the smelter. At the end of 2008, all mining operations were halted by the new owner of OMPL, Weatherly Mining International, while the smelter continued to operate. The closure of the Weatherly owned mines in Namibia, the primary feed source to the Tsumeb Smelter, meant that the smelter had to transition its business model from operating as a ‘captive smelter’ to that of a ‘toll smelter’. Its Ausmelt Top Submerged Lance (TSL) smelting technology and various ancillary plants made it especially suitable for accepting and treating complex concentrates that were available on the global market.

Jan 1, 2019

By Erminio Ferraris

The development of the mining industry in Sardinia dates from the application of the mining law of 1859, which, following the example of the French mining law of 1810, declared prospecting to be free, and suppressed the liens which had previously attached the mine to surface ownership. The first ore-dressing plants were installed by German engineers upon the classic models of the Harz and of Freiberg; but in 1880 Sardinia commenced to open a new path in that industry, utilizing the refuse from the mining of rich, selected minerals, of poor deposits, and of mixed ores. The first experiments were attempte to adapt the existing apparatus to local conditions, but progress was rapid, as was demonstrated already in 1887 by the calamine-dressing mill of Monte-poni, which exhibited a large plant designed in accordance with the experience gained, and constructed entirely in the machine-shops of the country, after new models and designs.' This example was followed two years later by the Sociékté Malfidano, with a large plant of the same sort, and with the reconstruction of the old-fashioned dressing-mill, built in 1880 by the Austro-Belgian Company. In 1900, almost all the mines of Sardinia had adopted the new designs, and the island contained 32 concen-trating-works, employing 2,000 h.p. and 1,924 workmen. Since that time, there have been added a large dressing-mill for blende at Gennamari, and two for calamine, at San Giovanni and at Masua, while the establishments at other mines have been enlarged and perfected. For the treatment of intimately mixed ores, a large establishment has been built upon the new

Jan 1, 1909

By H. Janas

In a gas/coal outburst the gas plays an active, driving part. The proneness of coal to outbursts can be determined by means of its gas emission properties, since coal that is liable to outbursts differs from coal with normal gas emission properties in that it liberates its gas from the sorptive bond more quickly. There is a risk of outburst when the flow of metha¬ne originally desorbed by the coal is sufficient to move the loosened coal which has been broken suddenly. The violence of a gas/coal outburst can be evaluated from the distance of projection of the mass of coal. It depends on the gas pressure and on the liability to outburst of the coal at the original centre of the outburst. Both factors are complementary in their effects so that the same work is done in a gas/coal outburst when there is a high gas pressure and low proneness to outburst as when there is a low gas pressure and a higher proneness to outburst. The gas pressure in the coal increases with its gas content. Consequently it is possible to deduce the gas pressure of a coal seam from its gas content. In the Federal Republic of Germany the risk of a gas/coal outburst is thought to exist when the desorbable gas content of the coal reaches or exceeds the value of 9 m3/ton and if the specific limit value of the proneness to outburst is exeeded. The Mine Ventilation Testing Station of the Westfalische Berggewerkschaftskasse has developed a new method for determining the risk of gas outbursts immediately after taking the samples at the coal face (1), (2).

Jan 1, 1980

By Charles H. Foreman

IN JUNE 1921, the Sullivan &lining Co., owned jointly by the Bunker Hill and Sullivan Mining & Concentrating Co. and the Hecla Mining Co, started work on the development of the Star Mine. The development work contemplated called for a crosscut from the Hecla workings on the 2000 level to the Star ledge. The length of crosscut necessary to encounter the Star ledge was approximately 8900 ft. from the Hecla shaft. By using workings formerly made by the Hecla Mining Co., only about 8100 ft. of actual crosscutting was necessary. This crosscut has a direction of S 20° W and would have a tendency to crosscut any ledges in the intervening ground.

Jan 1, 1924

By M S. Cassola

It’s expected that the world economy will face a stable and continuous growth in the demand of iron ore, reaching more than two billion tonnes per year within the next year. After decades exploiting resources with high content of iron ore, now the industry faces the challenge to exploit and beneficiate more complex ores.According to the industrial practice, the flotation technology is one of the most important and effective beneficiation processes to deal with low-grade iron ores around the world. However, even with this, it is still necessary to search for new processing routes or promote the optimisation of the existing circuits.The broad application of this technology is an outcome that deeply relies on the proper selection of flotation chemicals specifi cally designed for each system. New collectors are in continuous development as flotation performance significantly relies upon their optimisation.The reverse iron ore flotation in Brazil, mainly constituted by haematite and quartz, uses ether amines as collector for silica minerals and caustic corn starch as depressor for haematite. The process selectivity is highly impacted by the features of the etheramine, such as:• mono or di-etheramine,• neutralisation degree,• chain length,• branched or linear chain,• the flotation pH, and• the size distribution of the flotation feed.This paper describes the experience obtained from laboratory and industrial trials on different ores, conducted to improve the selectivity and recovery in the reverse iron ore flotation by selecting the required collector for low-grade ores.

Jul 11, 2011

By A. G. Matyas

Process improvements which have reduced the lead content of slag from the Brunswick lead blast furnace are described. Microscope examination and electron microprobe analyses, supported by the results of slag settling and viscosity tests, showed that typically about 70% of the lead in the lead blast-furnace slag was present in the form of entrained prills of metallic lead. The total lead content was found to increase with the magnetic susceptibility of the slag. Measurements in the furnace settler indicated the presence of a magnetite-rich layer between bullion and slag, arising from high magnetite levels in the slag. This layer was believed to inhibit the settling of entrained lead from the slag. Tracer tests showed that the average slag residence time in the settler was less than 2 minutes. Improvements in coke quality and sizing, which led to a reduction in the slag magnetite content, and the installation of a larger settler and a continuous Roy tapper, have all contributed to a significant decrease in the slag lead content.

Jan 1, 1977