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By Lee M. F

The Lady Loretta lead-zinc-silver mineral isation of north-west Queensland was discovered first by Placer geologists in 1968 as a result of a geochemical soil survey. The stratigraphic position, mineralisation and rock associations of the deposit are very similar to those of the Mount Isa lead-zinc-silver orebodies. Aspects of the exploration history, geo- chemistry and structural geology of the Lady Loretta deposit, are discussed. A geometric model of the Ore Horizon is given.

Jan 1, 1974

By WILLIAM SLOAN

B RITISH COLUMBIA in its mining activities is going ahead by leaps and bounds both in development and production. Mineral production for 1925 was $61,492,242 in value as compared to $48,704,- 604 in 1924, or an increase of about 26.2 per cent. This is a new record. It is the first time in the history of mining in British Columbia that we have gone over the fifty million mark. But we have got in the habit of making new records. The year 1924, with its mineral production of almost forty-nine million was a new record. And I am confident that when the mining history of 1926 is written it will be found that we have established yet another new record and that we can report another 25 per cent increase over 1925. What is the explanation? It is not only that the world is settling down, and settling up, after the war. It is not only that in the rebuilding, the refashioning in which all nations are busily engaged, the metals that come from our mines are needed. More than anything else, at least as far as we are concerned, it is because British Columbia has the resources and the fact that the province has been fortunate in recent years in finding men with the enterprise and the vision required to push ahead the labor of their development. From the ranks of our own people in Canada we have prospectors who have faith, energy and requisite knowledge. They are combing our hills season after season and they are of the type of manhood that does not know the meaning of the word quit. More and more these men are learning the importance of the guidance furnished by geological reports, and to an ever increasing extent such reports, thanks to the valuable work of the Canadian Geological Survey, covering areas little known to man, are made available to them-but it is recognized that in the opening up of our Province, containing within itself 372,000 square miles, it is essential that we should have the cooperation of our cousins on this side of the line as well as of our fellow citizens of the Dominion and of the Mother Country.

Jan 1, 1926

By K. Drescher

Excavations in deep level hard rock mines show rheological or time-dependent deformation responses to mining-induced stresses. These are generally not as dramatic as those seen in soft rock environments, such as potash and salt mines, but these deformations can nevertheless become substantial in time. It is usual to see total excavation closure at a much earlier stage than predicted by numerical models, and real-time measurements underground have confirmed that closure takes place on a more-or-less continuous basis, with highest closure rates observed after a blast and then slowly diminishing with passing time. This paper describes laboratory tests to determine the time-dependent response of hard rocks to loading, the results of the tests, and then quantifies these effects to explain the time-dependent phenomena observed underground. The primary intention of this work is to help explain the various time-dependent deformation processes around typical deep level hard rock tabular excavations. Three mechanisms were investigated in two typical hard rock types present in the deep level gold mines in South Africa, namely Ventersdorp Lava and Elsburg Quartzite. Uniaxial compression creep studies were done as the first part of the study followed by shear creep studies on discontinuities where crushed lava and crushed quartzite as well as a natural gouge were used as infilling. The last part of the study consisted of triaxial post-failure relaxation tests. The compression creep tests and the triaxial post-failure relaxation tests showed that the amount of energy dissipated by the lava is significantly less than for quartzite. For mines operating at depths greater than 2000 m the implication is that the lava must show a greater rockburst-proneness than the quartzite. Since the lava shows a lower post-failure stress relaxation, it can store sufficient energy for multiple rockbursts, which is seen in the clustering of multiple seismic events in the deep level mines. This study provides the first data available for energy change calculations in fractured rock masses, and provides the first general indications for rockburst intensities ahead of active mining faces.

Jan 1, 2003

By Klaus Schönert

Experimental investigations of single particle and interparticle breakage show that the microprocess in mills demands an energy input between 1 J/g and 10 J/g, if particles below 100 pm have to be comminuted. A system analysis of grinding media and roller mills is given in respect to the energy supply to the microprocess and the influence of the back stream caused by the compression of the material inside the active volume. The back stream diminishes the probability for capturing the particles in very fine grinding processes. Some possibilities are discussed how to solve this problem.

Jan 1, 1989

By D. W. Frommer

Processing nonmagnetic taconites by selective flocculation-desliming and flotation requires large volumes of water. If impounded without treatment these off-process waters require excessively large areas for containment. To discharge the waste water into natural waterways would contribute to stream pollution and likely would not be permitted. In Bureau of Mines experiments conducted in the Twin Cities Metallurgy Research Center&apos;s 900-lb/hr pilot plant, approximately 85 percent of water requirements for the flotation-based treatment of a Michigan nonmagnetic taconite were met by reclaimed water. Water reclamation of the off-process streams from flotation was accomplished by controlled additions of lime, sodium carbonate, and a synthetic flocculant to reduce turbidities to <1,000 ppm equivalent Si02, while maintaining a Ca(II) content of 516 ppm in the finished effluent. Flotation concentrates of good quality were obtained using the reclaimed water. The cost of chemicals used in water reclamation was approximately equal to the savings in flotation reagents attributed to recycling of the water.

Jan 1, 1970

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By T. Orgodol, P. Korpi

This paper describes the Boroo Gold Company (BGC) ore processing plant which is the first CIL/CIP plant in Mongolia. BGC is the first foreign investment in Mongolia since 1990 and follows the highest safety and environmental standards. Commissioning of the plant commenced in October 2003 and commercial production began in March 2004. Gold recovery is by gravity and conventional leaching and carbon adsorption. Detoxification of the leach tails is by the SO2/Air method before discharging the tails to the tailings pond. Ore types treated at Boroo are predominantly oxide with some transition ore as mining reaches the lower sulphide zone. There are several interesting technological issues and projects ongoing at Boroo which will also be discussed.

Jan 1, 2007

By Hans-Henrik Wallin

The stresses in the heads and shell of a grinding mill are largely dependent on the bending moment produced by the trunnion bearing. By using spherical roller bearings in a special narrow housing a short moment arm is obtained and the bending moment is reduced. For large mills a hydrostatic shoe bearing which also gives a short arm, can be used. Spherical roller bearings also require less maintenance and have a long service life. As the bearings are grease lubricated an automatic lubricator is used instead of an oil lube system. Service data from two Swedish mining companys confirm the fact that the above arrangements provide a long service life.

Jan 1, 1979

By Arthur P. Chaves, Lauro S. Norbert Costa, Adão B. Da Luz

A series of bench-scale bleaching tests have been carried out on kaolin samples from the Rio Capim area( northern Brazil) at CETEM/CNPq. The whole sample has been homogenized and submitted to particle size separation, when the + 44 µm fraction has been discarded, prior to being bleached. The main objective of this series of tests has been to evaluate the possible effects of interactions among variables which are believed to play important roles in the bleaching operation on the efficiency of the process itself in terms of the brightness achieved in the final product The tests have been planned according to a classical four-variable, two-level factorial technique. The chosen variables have been the pH, sodium dithionite addition, aluminium sulphate addition and bleaching time. The study has shown that, apart of time, all other three variables are significant. None of the interactions among them have shown to be of significance. Brightness numbers close to 88 have been obtained in the products, which represents an improvement, since brightness for the non-bleached - 44 µm Rio Capim kaolin sample averages 83.

Jan 1, 1995

By F. H. Gilpin

SINCE Noah pitched his ark within and without with pitch, the use of asphalt in human endeavor has been increasing-for Noah&apos;s pitch was asphalt. Asphalt is a bituminous material found in nature, either pure or admixed with smaller or greater quanti-ties of mineral and non-mineral materials, or obtained by the refining of crude asphaltic-base petroleum under proper methods of control. Native or "natural" asphalts are scattered through-out the world, though the commercial value of the various deposits varies greatly, depending upon both their accessibility and magnitude and the quality of the material found. It is an acknowledged fact that such asphalts have been produced through natural causes by practically the same application of tempera-ture and pressure as are used in the modern refining of crude asphaltic-base petroleum. The best known of all the native asphalt deposits are those of Trinidad Lake in the Island of Trinidad, British West Indies, and of Bermudez Lake in Vene-zuela. Asphalt from Trinidad Lake, after refining to remove organic and some inorganic diluents, contains approximately 35 per cent, of inorganic residue, and the asphalt thus produced must be fluxed with lighter asphaltic or semi-asphaltic base oil to make it com-mercially utilizable. The refined asphalt obtained from the Bermudez Lake deposit contains from 4 to 6 per cent. of inorganic material which cannot be removed. This asphalt, also, must be fluxed to produce com-mercial products. Small quantities of similar materials are available in other locations. The best pure native asphalt&apos; is known as. gilsonite and is mined in com-mercial quantities in the State of Utah. In numerous places in the United States, particularly Oklahoma and Kentucky, there are deposits of sand¬stone and limestone impregnated with bitumen, which are known as rock asphalts. These rock asphalts may be used, particularly in the paving industry, either as found or by slight fluxing; from some deposits the asphalt is extracted and marketed commercially.

Jan 2, 1923

By G. W. Preckshot, N. G. DeLisle, C. E. Cottrell, D. L. Katz

MOST crude oils contain asphaltic substances that may be naturally or artificially precipitated. In the Greeley field, California, this asphaltic bitumen is precipitated during the flow of the oil from the reservoir to the stock tank. The mechanism of such precipitation is not well understood. This paper presents the progress that has been made by using the electron microscope as a new tool and by observing the effects of the streaming potential on the formation of bitumen particles. Crude oils at atmospheric pressure viewed in the electron microscope in very thin films under a vacuum showed no asphaltic particles. A technique of preparing slides of thin films by dilution of the oil with benzene and washing in petroleum ether was used at first, and these observations showed that the solvents caused the formation of the particles, varying from 0.01 to 0.2 micron in diameter. The electrical effects of fluids flowing through porous solid were studied, with emphasis on the formation of colloidal particles by the streaming potential. The streaming potential of crude oil flowing through sand was measured and was shown to be responsible for the formation of bitumen particles. These results bring out a new phenomenon, which may occur when crude oil flows through the porous oil reservoir.

Jan 1, 1942

The largest variety of asphalt and related bitumen deposits in this country is found in Utah. Utah is one of the few places in the world where the hydrocarbon minerals, gilsonite or uintaite, wurtzilite (trade name elaterite) and ozokerite are produced. These bitumens occur in an area embracing nearly 10.000 square miles in eastern Utah near the Colorado line. This area is largely in the western part of the Uintah basin. The bitumens are in the Tertiary horizon in the various divisions of the Eocene series. Cilsonite is an asphaltite derived from petroleum, wurtzilite is an asphaltic pyrobitumen derived from petroleum, and ozokerite is a native mineral wax resulting from the metamorphosis of paraffinaceous petroleum.

Jan 1, 1925

"The largest variety of asphalt and related bitumen deposits in this country is found in Utah. Utah is one of the few places in the world where the hydrocarbon minerals, gilsonite or uintaite, wurtzilite (trade name elaterite) and ozokerite are produced. These bitumens occur in an area embracing nearly 10,000 square miles in eastern Utah near the Colorado line. This area is largely in the western part of the Uintah basin. The bitumens are in the Tertiary horizon in the various divisions of the Eocene series.Gilsonite is an asphaltite derived from petroleum, wurtzilite is an asphaltic pyrobitu¬men derived from petroleum, and ozokerite is a native mineral wax resulting from the met-amorphosis of paraffinaceous petroleum.Gilsonite is produced by the Gilson Asphaltum Company, a subsidiary of the Bar¬ber Asphalt Company, at Watson, Utah. A narrow guage railroad, seventy miles in length and with a 7 1/2 percent grade over the Book Cliffs on Baxter Pass, was constructed by the company from the Denver & Rio Grande Western railroad main line in order to open up the gilsonite deposits. The veins range from narrow upward to 18 feet in width. The Rainbow vein at the present wokings is eight feet wide, vertical, and has sandstone walls. This vein has been opened up for a distance of about three miles and in some places four hundred feet deep. Forty men usually are employed with a production of eighty tons per day."

Jan 1, 1925

Discussion of the paper of E. J. Hall and C. W. Drury, presented at the Butte meeting, August, 1913, and printed in Bulletin No. 78, June, 1913, pp. 1059 to 1066. A. M. SMOOT,* New York, N. Y. (communication to the Secretary +) :-The nails method is given in many text books on assaying as a standard method for gold or for gold and silver in ores. It appears to be taught in the laboratories of technical and scientific schools as a standard method, and to some extent it is used by assayers in actual practice, although the class of ores to which it may be applied is limited to those free from reducible metallic compounds, the metals of which would enter the lead button. The experiments of Messrs. Hall and Drury show the inaccuracy of this rnethod for silver, in heavy sulphides, but not so clearly the short-comings with regard to gold. It seems certain that low silver is caused by the solubility of silver in iron-alkali sulphide as compared with its solubility in molten lead; that is, silver is distributed between iron-alkali sulphide and metal in the charge in proportion to solubility at the particular temperature of the fusion. Lead is a fixed quantity in these assay charges, but iron-alkali sulphide increases with increased sulphur, so the more sulphur in the charge, the lower the silver results.

Jan 11, 1913

By Stephen H. Hall

INTRODUCTION At some point in the design and development stage of a mineral venture, the assay laboratory building, its interior layout, and major pieces of analytical equipment must be specified for construction or purchase. Even the most experienced chemist would have difficulty in proposing useful specifications without a good deal of investigation into the kinds of analytical tasks that the laboratory will be expected to address, the probable workload, and the operating time constraints. This chapter will provide a logical approach to laboratory design that starts with such an investigation. Specific examples throughout the chapter are drawn from the author&apos;s tenure as Chief Chemist at Barrick Mercur Gold Mines, Mercur, Utah, from 1982 to 1985. It is necessary to understand the nature of a modern production laboratory, and to recognize that its operations bear more resemblance to its parent processing plant than to a research, teaching, or custom analytical laboratory. The assay lab is a processing facility unto itself, where samples and reagents are the raw materials, and assay results are the final product. Its most efficient operating mode is as an assembly line, treating samples in a nearly continuous flow. Nevertheless , there are important differences between the lab and the process plant. The products - assays - are individually unknown quantities until they are "produced.&apos; This can vastly complicate quality control compared to the process plant. Capital costs are general 1 y small compared to the plant, but the ratio of operating costs to capital costs for a laboratory is often very much higher than for the plant. This is due to the labor intensive nature of analytical work. For instance, during Fiscal Year 1984 at Barrick Mercur Gold Mines, labor costs for the laboratory staff represented about five percent of the total labor budget, while the laboratory building and equipment represented only about six-tenths of one percent of the original start-up capital. Failure to recognize both the similarities and differences between laboratory and plant operations is the foremost cause of difficulty encountered in designing a laboratory. The

Jan 1, 1986

By E. J. Hall

(Butte Meeting, August, 1913.) THE iron-nail method of assaying has been used for a number of years, but has not met with the approval of all assayers. The method possesses advantages which may be given as follows : (1) no preliminary treatment is required ; (2) a lead button of proper size can be obtained (3) it is economical. On, the other hand, it has its disadvantages, which may be summed up as follows: (1) it is not applicable to ores containing large amounts of impurities other than sulphur, as practically all the base metals will contaminate the lead button ; (2) the slag is unsatisfactory in the larger number of fusions; (3) the method was known to give low silver results under certain conditions and the gold results were questionable. It was with the idea of determining the extent of this latter disadvantage that the following investigation was undertaken. It is well known that the fusion obtained in the lend assay is far more satisfactory than that in the " nails method " for gold and silver. The principal difference in the charges as a class is the presence of considerable reducing agent in the lead charge, and a limited oxidizing action in the nails charge, due to PbO. The possibility of improving the nails fusion by simulating the lead charge was the reason for using argol in some tests, even though there were reasons for expecting this would have -au objectionable effect on the results.

Jan 6, 1913

By Charles R. Keyes

I. INTRODUCTION. FOR a period of several years, and in a large number of cases, the Metallurgical Laboratories of the New Mexico School of Mines were employed in umpire work. During this time many important local problems were solved. Against the results of careful chemical analyses of ores, assay-returns were often checked. In many cases the assay-methods of mine and custom-smelter were compared, and both often found faulty for the ore concerned. A wide range of ores was covered. Many of the chemical analyses and assays were made by Dr. F. C. Lincoln, Professor of Metallurgy, now of the Montana State School of Mines. A varied series of instructive assays was prepared by Prof. R. B. Brinsmade, now of the West Virginia State University. Single assays and given series of tests were undertaken by H. T. Goodjohn, now chief chemist to the Cia. Metalurgica de Torreon, Coahuila, Mexico; by H. J. Hubbard, now superintendent of the Butters Divisadero Mines, Jocoro,. San Salvador, C. A.; by E. D. Morton, now superintendent of the Arizona & Nevada Copper Mining Co., at Lunning, Nev. ; and by A. W. Edelen, now superintendent of the Angangueo Unit of the American Smelting & Refining Co., in Michoacan, Mexico. A critical comparison of assay-methods that were found to be followed in the case of certain gouge-ores mined in the Mimbres range in New Mexico, and about which there had been much controversy, was made by D. F. Riddell, then Acting Professor of Assaying, and now superintendent of the Providentia Mines Co. of Parral, in Chihuahua, Mexico. To him is due the credit of much that is contained in the following notes, which be has generously permitted -to be used in advance of the publication of the complete results.

Jul 1, 1911

By G. Reuben Yourt

THIS paper is chiefly a description of the improvements in dust control chat have been brought about in the assay office grinding room at Wright-Hargreaves. The fume exhaust systems are briefly included because they also are important to the health of the employees. There are three chief factors which determine the efficiency of a dust control system: First, the amount of time and thought spent in designing it. Second, how close! y it is kept up to date with the growth of the plant-a system that is adequate for the number of machines operating when it is installed may fall short of fulfilling its purpose as the plant expands. Third, unless someone is held directly responsible, a system is likely to get out of repair and gradually lose its efficiency-this can easily be detected by regular dust surveys. In designing the present system at Wright-Hargreaves, the object kept in mind was to reduce the dust concentration of all operations to a safe limit, chat is, well under 300 particles per cubic centimecer of air. By doing this, a condition would be attained chat would make it possible to discontinue the use of respirators, which at best are not very comfortable and do not remove all of the hazardous fine-dust particles.

Jan 1, 1941

Cyanide-extractable gold is far more meaningful in the definition of ore, and control of extraction, than fire- assayable or aqua regia digestible gold. The use of cyanide- extractable gold addresses the significant problems of over- as well as under-assaying by fire and aqua regia digests. The problems of conventional control or diagnostic cyanidation extractions: lengthy extraction, and masking by pregrobbing in cyanidation extractions for assay purposes; are surmounted with a novel activator - Leach WELL. Full extraction of liberated gold, insignificantly affected by preg-robbers, can now be achieved within 30 minutes. This can assist in reducing common gold losses presently often hidden by inappropriate mine call factors, and/or high grade cut values. This paper includes a discussion of fundamental mechanisms of cyanidation, preg- and assay-robbing, which underlie the phenomena Involved.

Jan 1, 1992