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By AIME AIME

A SYMPOSIUM on current. conditions in Mexico, particularly in the oil and mining industries, was a most successful feature of the May meeting of the New York Section of the A.I.M.E. Heath Steele, vice-president of The American Metal Co.. Ltd., with an intimate knowledge of Mexico gave the principal address, and asked that his analysis of the present situation he regarded neither as an endorsement of Mexico's policy nor as the criticism of a disgruntled operator. To explain the .attitude of the great mass of the Mexican people towards recent developments, he first described briefly the political, social, and religious beliefs and customs of tile Mexican Indian. In spite of their contact with foreigners these beliefs and customs have remained unchanged throughout many generations. The old communal spirit and the idea of common ownership of the land still persist especially in the rural districts and villages; the old custom of a council for local self-government is reflected in the present-day labor committee. Mr. Steele discussed in order land oil, and mines.

Jan 1, 1938

By Orville R. Lyons, A. C. Richardson

DURING the past few years there has been a growing demand by coal operators for detailed information about the performance characteristics of the various dryers now being manufactured, preferably in such a form that the information could be used to determine the type of dryer best suited to a particular drying problem. A few operators have been desirous of going even further, because they are of the opinion that present-day dryers are not properly designed and that fundamental studies of dryer design should be undertaken. This growing demand for a method of dryer evaluation and the indicated need for fundamental research resulted in the sponsorship by Bituminous Coal Research, Inc. of a project at Battelle Memorial Institute to investigate the thermal drying of coal. In investigating this problem, the most feasible method of attack appeared to be a survey of active operations to determine the present status of the thermal drying of coal. Data were obtained, usually by actual plant tests with the cooperation of the various preparation engineers and their staffs, for Q screen-type dryers, 8 rotary- type dryers, 3 continuous-pallet-type dryers, 2 flash-type dryers, I tray-type dryer, and I cascade-type dryer. The testing program provided: (I) data for 24 coal- drying operations, (2) information about dried, (3) information about the previous treatment that the coal had received, and (4) information about operating costs. The data obtained through the dryer survey and relationships determined from the data make it evident that all of the types of dryers included in the survey can be operated with the same degree of effectiveness if each type of dryer is used to dry the sizes of coal for which it is best suited. It should be noted that it is usually undesirable and often impossible to dry different sizes of coal in one type of dryer. By use of the data in the report, any prospective dryer user, having determined the surface moisture percentage and screen- size analysis of the coal to be dried, the tons of water to be removed per hour, and the final surface moisture percentage desired, should be able to determine with a fair degree of accuracy: (I) the difficulty of the drying problem, (2) the approximate cost of drying, (3) the required dryer inlet gas temperature and volume and exhaust gas temperature and volume, (4) the type of dryer to use, and (5) the size of dryer required. The method of testing the dryers and determining the difficulty of drying can be used by operators already having dryers to check the performance of their particular dryer and determine whether they are operating effectively. Considerably more information was obtained from the survey of thermal drying than was anticipated when the survey was first considered. However, a great deal of work still remains to be done in the field

Jan 1, 1948

The Martha Mine is an open cut operation situated in the midst of Waihi town which has been operating since 1987. Since then it has produced some 700,000 ounces (oz) of gold and 4,000,000 oz of silver from an epithermal vein system. It was previously worked by underground methods from 1880 to 1952 to a depth of 600 m producing 5 million ounces (Moz) of gold and 30 Moz of silver. The licensed reserves are scheduled to be mined out early in the year 2001. An additional economic resource of over 750,000 oz of gold has been identified which can be accessed by deepening the pit a further 50 m along the main Martha vein. This would extend the mine life to the year 2007. Applications were lodged on 4 July 1997 for the necessary resource consents, discharge permits and variations for the current Mining Licence conditions. The extension project requires approval from the District Council, Regional Council and the Ministry of Commerce. The consent and permitting process is extensive because of the urban setting of the mine. An approach to keep the extension as similar as possible to the current operations was adopted to give the community and authority confidence in the proposed extension. This paper summarises the extension detail and the permitting requirements it has had to address despite the extension being "more of the same". The permitting process has been exhaustive with little recognition of the standards already achieved in protecting the environment which are recognised worldwide.

Jan 1, 1997

By Tell Ertl

An annual invitational address by an outstanding man in mining, geology, or geophysics who has contributed significantly to the progress of technology in these fields. IN 1954, the first year the award was conferred, Fred Searles, Jr., remarked, "The earlier years are the easiest." In this, the second year, it was easy to choose the outstanding mining engineer. Our conferee this year has been destined to mine. He comes from pioneer stock, and though a son of the American Revolution he is most proud that all four of his grandparents came to the Jordan River Valley of Utah the "first summer," which all Utahns will recognize as 1847. At the time of discovery of high-grade ore in Bingham, his grandfather, Archibald Gardner, had a crew of men getting out saw timber in the area. The first claim staked in Bingham Canyon was named the Jordan, and Bishop Gardner was the colocator of the claim as well as the man to record it. E. D. Gardner was born in West Jordan, Utah, in view of Little Cottonwood Canyon, the site of the Emma Mine. Park City in the Wasatch Mountains a few dozen miles to the east, and Tintic, not much further to the south, were developing their vast ore-bodies throughout his youth. As a boy he was near the present Midvale metallurgical area and could see the Lark and Bingham Canyon mine dumps and imagine the mining activities at Tooele, Ophir, and Mercur just over the nearby Oquirrh Range. He was 11 years old when the first car of copper ore was shipped from Bingham Canyon. It was not surprising that he attended the University of Utah and graduated with an engineer of mines degree. Five years with the Utah Apex in Bingham Canyon as chief engineer and assistant superintendent completed his training for the 44 years of unselfish and lightly rewarded service he was to give the mining industry as a Government engineer. All of us in mining are familiar with the great work he carried on and directed during the genera- tion he supervised the Southwest Experimental Station at Tucson. He has written scores of papers and books. His observations and experiments on drilling and blasting have led to the important improvements in this field during the past quarter century. Whereas those of us who consider ourselves widely informed about underground metal mining methods make hasty trips through a half dozen or dozen mines a year, our conferee has visited them all—not only the metal mines, but also coal and hundreds of nonmetallic mines, in the United States, Canada, Latin America, and overseas. His keen observations and analytical mind have resulted in an encyclopedic knowledge of mining and mines. His improvements in mining technology have been steady and predictable. His elucidation of mining problems to the many young engineers that have come under his guidance have made them grow strong and useful to his industry. When he chooses to stop, his influence will continue to expand and prosper because of the inspiration and dedication he instilled in so many of us. The profits from his ideas have been distributed throughout the mining industry. He has remained a technical man who felt that he could serve the mining industry best as a Government engineer. But he is the staunchest advocate of the belief that the public should gain from his work through private industry. This is not the first recognition E. D. Gardner has received. The Department of the Interior awarded him the coveted Medal for Distinguished Service in October 1949, and he received the Engineering & Mining Journal's Salute in March 1951. His friends who are presenting him the Daniel C. Jackling Award today know this great mining engineer simply as "Ed" Gardner.

Jan 1, 1956

The Annual General Meeting of the Institute was held in Kelvin House, Johannesburg, on Wednesday, 26th August, 1970, at 4.15 p.m. Mr. J. K. E. Douglas (President) was in the Chair. There were also present sixty-three Fellows, thirty-five Members, one Graduate, eight Associates, five Students and nineteen Visitors, making a total of one hundred and thirty-two. The President declared the meeting open at 4.20 p.m. OBITUARIES The President: 'It is my sad duty to announce the deaths of the following members of the Institute. Dr J. A. Papenfus, Fellow, who joined the Institute in 1942 and passed away on the 28th of May, 1970. Mr D. G. Beadle, Fellow, who joined the Institute in 1946 and passed away on the 17th of June, 1970. Gentlemen, Derek Beadle was very well known in this Institute. His papers on dust will be remembered and, at the time of his untimely death, he was one of our assistant editors. As a mark of respect to the memory of the deceased and in sympathy with the bereaved, I would ask you to rise and observe a few moments' silence.' MINUTES The President: 'May we confirm the minutes of the General Meeting held on 15th April, 1970, as published in the July, 1970, issue of the Journal'. Agreed. WELCOME TO VISITORS The President: 'Ladies and Gentlemen, we are honoured this afternoon by the presence of many distinguished guests and I extend to you all a most cordial welcome. We are happy to have with us Dr A. A. von Maltitz, President of the Chamber of Mines of South Africa, who is also Honorary President of this Institute. We also have one of our Honorary Vice- Presidents, Mr T. L. Gibbs, the Government Mining Engineer; Mr D. E. Hamm, President, Institution of Certificated Mechanical and Electrical Engineers, S.A.; Mr S. C. M. Naude, Director, Witwatersrand Technical College; Mr I. R. G. Stephen, Senior Vice-President, The S.A. Institute of Electrical Engineers; Mr G. M. Tompkins, President, The S.A. Institution of Mechanical Engineers; Professor P. B. Ackermann, President of the Geological Society of S.A.; Mr A. S. Robinson, Vice-President of the S.A. Institute of Civil Engineers; Professor W. Mare, President of the Institute of Land Surveyors of the Transvaal; Mr B. D. Charlton, President of the S.A. Institute of Assayers and Analysts; Mr R. Hemp, The President, The Mine Ventilation Society of S.A.; Mr L. J. Prince, The President, The S.A. Association of Mine Managers; Mr J. Botha, The President, The S.A. Institute of Foundrymen; Mr G. Niterl, The President, The Institute of Welding; Mr M. R. Gericke, President, S.A. Council of Professional Engineers; Mr N. A. Honnet, Chairman, Orange Free State Branch; Mr P. R. C. Cooke, Chairman. The South African Chemical Institute (S. Tvl' Section). Gentlemen, we are very honoured indeed, to have these distinguished gentlemen with us this afternoon, as our honoured guests. We are also pleased to have with us, one of our Honorary Fellows, Mr F. G. Hill, and several Past-Presidents. I also extend a very warm welcome to all our lady guests and to all our other visitors.' MEMBERSHIP The President: 'I have pleasure in announcing that the names of the following candidates, having been published in accordance with By-Law 5.2.2, Council has elected them to membership in the following grades: NEW APPLICATIONS Fellows: Herbert Dalton-Brown, Stephen William Morel. Members: Clive Lester Workman-Davies, Basil James Russell Botha. Students: Timothy Nigel Watson, John William Hairbottle. I wish to welcome the new members to the Institute and to congratulate those members who have been transferred to a higher grade.' ANNUAL REPORTOFTHE COUNCILAND ACCOUNTS FOR THE YEAR ENDED 30th JUNE, 1970 The President: 'I now have pleasure in presenting to you, the Annual Report and Statement of Accounts for the year ended June, 1970. These have been handed to you this afternoon and, as is customary, I propose they be taken as read. Before moving their adoption, however, I would like to refer to some of the salient features, leaving as is usual, the task of dealing with the finances, to our Honorary Treasurer. It is encouraging that membership has continued to grow, and now stands at 1,613, an increase of 61 over last year's total. Your Council, however, is aware that there are still people in our mining and metallurgical industries, who could qualify for membership, but who have not yet joined the Institute. A drive to increase membership was accordingly organised, and members of Council were given the responsibility for campaigning in sections of industry, and for publicising the objectives and advantages of belonging to the Institute. Up to now there has not been much reaction to this campaign, but I hope we will see results in the coming year. At the same time, Council has recognised the need for change in the conduct of the Institute's affairs in order to meet the changing needs of our membership. Our members, both mining and metallurgical, are in the first place, geographically more widely dispersed than they used to be, and secondly, with the growth of the metallurgical industry, their technical interests are now more diversified. The Institute must cope with these changing needs if we are to continue to perform a useful function. The

By F. Habashi

Conclusive evidence is given showing that the dissolution of gold in cyanide solution follows mainly the over-all equation A similar equation can also be written for the dissolution of silver. Theoretical derivation of the velocity equation for this reaction has been obtained, which describes quantitatively the experimental facts. The equation is as follows: where [CN-] and [O2] = the concentrations (in moles/ml) of cyanide and dissolved oxygen, respectively. DcN- and Do2 = the diffusion coefficients of cyanide and dissolved oxygen; 1.83 x 10-5 and 2.76 x 10-5 cm2 sec-1, respectively. A = the surface area of the metal in contact with the aqueous phase, in cm S = the thickness of the boundary layer; varies between 2 and 9 x 10-3 cm, depending on the speed and method of agitation. Rate being expressed in g. equiv. sec-1. INTRODUCTION During recent years a number of papers have been published on the kinetics of dissolution of gold and silver in cyanide solution.1,6 The authors agree that the rate of dissolution is diffusion-controlled, but disagree regarding the mechanism of the reaction. Some authors'-3 support the Bodlander equations: The apparently conflicting results, when critically reviewed, are concordant and lead to the conclusion that the proper equation for the dissolution reaction should be only Eq. 1. This conclusion is based on the following facts: 1) For every 2.2 equivalents of metal dissolved one mole O2 was consumed. 2) For every 1 equivalent of metal dissolved, 2 moles of cyanide were consumed.' 3) Hydrogen peroxide is formed during the dissolution of gold or silver, and for every 2.2 equivalents of metal dissolved, one mole H2O2 was produced.1,2 The fact that Kudryk and Kellogg4 did not detect H2O2 during the dissolution of gold should not throw doubt on the many affirmative reports of other investigators. Lund2 has shown that depending on the crystalline nature of the silver surface, (e.g. method of etching the sample) H2O2 may undergo catalytic decomposition heterogeneously according to: Further Kudryk and Kellogg4 carried out their experiments in the presence of 0.5% KC1 to achieve a greater electrolytic conductivity, and Matsudaira7 has shown that H2O2 is catalytically decomposed (homogeneously) in the presence of C1- ion in alkaline solution. 4) Experiments carried out by Boonstra8 and Lund2 showed that the dissolution of gold and silver respectively in KCN + H2O2 in the absence of oxygen was a slow process. Thus the reaction takes place to a minor extent only. Further kinetic studies showed that: 1) The rate of dissolution depends on the surface area of the metal in contact with the liquid phase, thus indicating that the process of dissolution is a heterogeneous process. 2) The rate of dissolution depends on the speed of stirring,5,6 thus indicating that the process is controlled by a physical phenomenon.

Jan 1, 1967

By Dever Ashmead

ANTHRACITE was first mined in the Wyoming Valley and sold as an article of commerce in 1808. As some preparation has always been necessary to make it ready to burn, the preparation of anthracite must date back over a hundred years. Two vital factors have determined to a large extent the degree and method of anthracite preparation. These are, first, the character of the beds worked and the methods by which they were mined and, second, the equipment used and practices followed in the burning of the coal. It is not the intention here to go deeply into these phases of preparation as a paper of no mean length could be prepared on the history of either. Rather, the intention here is to point out the main considerations and to show the influence they have exerted on the preparation of anthracite. MINING METHODS AND THEIR RELATION TO PREPARATION In the beginning f the nineteenth century, the coal beds were virgin with the possible exception of some outcroppings that had been worked, to a slight extent, by the Indians. It is known that the American aborigines had a knowledge of the use of this fuel, because when the Wyoming Valley was purchased from them, in 1754, they mentioned the fact that, by selling the land, they would lose their coal.

Jan 9, 1921

By Charles D. Walcott

The following acts of the Directors are reported for the information of members At a meeting held June 20, 1907, Dr. Charles D. Walcott, Director of the U. S. Geological Survey, Washington, D. C., having been recommended by unanimous vote of the Council, was unanimously elected an Honorary Member of the American Institute of Mining Engineers, in recognition of his personal services to American geology, and of his generous co-operation with this Institute, to the Transactions of which he has not only himself made valuable contributions, but has also encouraged the preparation of such contributions by the members of the U. S. Geological Survey under his charge, his liberal policy in this respect having gone so far as to permit the preliminary publication by the Institute of important results reached by the geologists of that Survey, even before their final and full publication as public documents. This wise and generous course has not only brought the U. S. Geological Survey into intimate and sympathetic relations with the mining industry of the world, but has also enriched the Transactions of the Institute, especially in the department of the science of ore-deposits, with many valuable papers. At a meeting held Jan. 14, 1908, Mr. Charles Kirchhoff was unanimously re-elected a Trustee of the United Engineering Society, to serve for a second term of three years. At a meeting held Feb. 18, 1908, directly after the adjournment of the annual meeting of the Institute, the following officers were elected for the ensuing year: President, James Gayley: Vice-President, James Douglas; Secretary, R. W. Raymond; Treasurer, Frank Lyman.

Mar 1, 1908

By V. K. Karra

"A simplistic algorithm jar simulating the rod or ball mill Bond grindability test applied to ores and minerals is presented. A performance comparison between the present algorithm and a previously published algorithm by Kapurot, modified in this work jar a fair evaluation, is also given. A worked example is furnished jar leading the reader through the various calculations.IntroductionThe Bond grindability test is widely used for the prediction of the power requirement of an industrial grinding mill. The procedures for conducting this test in either a ball or a rod mill are available(1). In the case of a ball mill, batch grind abilities have been correlated to Bond grindabilities to help monitor day-today variations in ore grindability for the purpose of plant control( 2,3). Of special interest is the algorithm presented by Kapur(3) for the simulation of the Bond test. In practice, the test lasts from 6 to 14 cycles (4 to 10 hours). With this algorithm, one can predict the Bond grind ability using information available from only the first two cycles.Sometimes the prepared feed for the grindability test contains too much fines compared to the total product desired at the mesh of grind under consideration. In such a case, the operator separates the fines from the test feed and adds to the remaining coarse fraction an equal amount of fresh feed. This combined feed then forms the feed to the first cycle of the test. In the present work, Kapur's algorithm is modified to include this special case. A new and relatively simpler algorithm is also presented. Statistical equations relating work index to pertinent variables are also given."

Jan 1, 1981

By Gordon S. Farnham

THIS paper summarizes the results of investigations carried out at Sydney Mines, N.S., and at Ottawa, following the disaster at Princess colliery, December 6th, 1938. The Honourable Minister of Mines for Nova Scotia appointed A. E. Cameron special investigator to enquire into and report upon the cause of the rope failure. Public hearings were held in Sydney Mines and evidence taken from many witnesses. The site of the accident was examined in detail and investigations made of the rope layout and colliery practice. At the request of the special investigator, the Department of Mines and Resources, Ottawa, kindly undertook technical and scientific examination of the broken ends of the rope. These investigations were carried out in the Metallurgical Laboratories of the Department of Mines and Resources, under the supervision of G. S. Farnham, Metallurgist for the Department. Valuable assistance in interpretation of many features of the investigation was received from other sources. Acknowledgment is due to Messrs. Stuewe, McCall, and Gordon, and other members of the staff of the Dominion Steel & Coal Corporation; to Messrs. Morrison and Scott, and other members of District 26, United Mine Workers of America; and to Messrs. Timm, Parsons, Haycock, Haanell, and other members of the staff of the Department of Mines and Resources, Ottawa, for helpful ad vice and technical assistance in assembly of information, and preparation of material and interpretation of evidence obtained.

Jan 1, 1939

By Charles A. Mitke

Discussion of the paper by CHARLES A. MITKE, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 105, September, 1915, pp. 1941 to 1958. GERALD SHERMAN, Bisbee, Ariz.-Mr. Mitke justly might have made much stronger his claim for increase in efficiency of labor due to the introduction of forced ventilation. The product per man shift in stoping in the Gardner division has practically doubled. While it is true that improved methods have been responsible for a great part of this gain, and what is due to better ventilation cannot be definitely known, yet it is also true that the results could not have been obtained in that division as it was in 1912. . The paper discusses the two systems of ventilation in use, exhaust and pressure. In both the object is the same, to take foul air or gas out of the mine by the most direct course and replace it by fresh. In coal mines, the exhaust system is in almost universal use, and since the most advanced work in ventilation has been in that class of mines, it was naturally the first one to be considered. It has the advantage of leaving all adits, shafts, or other openings free for use. Doors are only needed to direct the course of the air, and not to confine it. Its disadvantages appear in case of fire, or if the ground over the mine is much broken by subsidence. The fan must work in gas in the case of a -fire, and may be. damaged or destroyed either by heat or by corrosive gas. At the time of the fire in the Lowell division of the Copper Queen, a small exhaust fan was placed over a ventilating raise, but the vanes and housing were destroyed by sulphurous gases within a few weeks. If the ground above the mined area is much broken, as is frequently the case when the ore deposit is thick vertically, a good deal of air is likely to pass through it, particularly if it is near the surface. Leakage from this source is a loss to the exhaust system by short circuiting, which is exaggerated by a contraction or block in the air course. It serves as an added outlet in the pressure system. This is strikingly shown at the United Verde, where many jets of steam may be seen coming up through the ground above the stoped country on a cold day.

Jan 12, 1915

By J. Spotts McDowell

INTRODUCTION The magnitude of the thermal expansion of silica brick, and its inability to withstand rapid temperature changes, present problems of considerable importance in the manufacture of siliceous refractories. In the study represented by the experimental data herein described, these problems are considered from the point of view afforded by the results of recent investigators: Fenner and his associates of the "Geophysical Laboratory, Washington, D. C., who have established the stability relations of the silica minerals, and Endell and co-workers in Berlin, who have studied the changes brought about in the constitution of siliceous refractory materials upon the application of heat. In the process of manufacture, the quartzite from which the brick is made changes in part into cristobalite and tridymite. The attempt is herein made to determine by microscopic methods the degree of transformation in various specimens of test bricks manufactured at slightly varying temperatures of burning, with varying coarseness of grain, and to determine the effect of repeated burning. The effect of variations

Jan 10, 1916

By N. A. White

Whereas the ultimate world supply of energy minerals-defined as fossil fuels and fissile materials - is controlled by geological factors, the actual supply at any particular time is controlled by economic feasibility, technological innovations and /or political decisions. This paper identifies and discusses the principal uncertainties surrounding the international availability of energy minerals from now until the end of the century. A brief comparison is also made between energy and non-energy minerals. Genuine shortage s of energy minerals are now of a very long-term nature, whereas artificial ones may occur at any time and have a serious effect on the world economy due to the dependence of most OECD countries on imports of energy mineral . This paper argues that events over the last decade, such as the demand for a New International Economic Order, the OPEC increase in crude oil prices and the growing international lobby on environmental issues especially relating to nuclear safety - will progressively lead to a major, long-lasting transformation of the energy scene world wide. This transformation will encompass demand, in terms of conservation and efficiency, the supply mix of the various energy minerals , the supply system and the structure of the different energy industries . It is already affecting the role of governments and reaching into the question of national sovereignty both of developed countries, such as the U.K., Norway and Australia, and the developing countries, thereby making energy minerals a key area of international relations.

Jan 1, 1978

By Joshua I. Tracey, Mackenzie Gordon

THE bauxite deposits in central Arkansas were formed by weather¬ing, in early Eocene time, of fresh or kaolinized nepheline syenite above the water table in a subtropical climate of fairly continuous moisture. Four types are recognized: (1) residual bauxite deposits on kaolinized nepheline syenite, (2) residual deposits on kaolin and bauxite detritus, (3) alluvial deposits of sorted pebbles and pisolites of early Wilcox age, and (4) rubble deposits of later Wilcox age. All were invaded by kaolin and siderite during subsequent burial by Eocene sediments. PART I-FIELD RELATIONS OF THE DEPOSITS The Arkansas bauxite region for years has produced about 95 pct of the domestic supply of bauxite of the United States and it contains today reserves of more than 40 million tons-nine tenths of the known domestic reserves. During World War II, the Arkansas bauxite deposits were explored jointly by the U. S. Geological Survey and the U. S. Bureau of Mines. Some 6000 holes were drilled by rotary rigs under contract to the Federal Govern¬ment, which resulted in the discovery and delimiting of approximately 20 million tons of ore in place. Detailed study of the many sections cored through the bauxite, of data from a much greater number of drill holes made available by all the operating companies, and of the extensive mine faces exposed in the strip pits, has yielded valuable geologic information about the origin of the deposits. It is now possible to piece together a paleotopographic picture of the deposits and the now-buried land surface on which they formed. The bauxite region in the center of Arkansas (Fig 1) contains two producing districts: one in Pulaski County, just south of Little Rock, and the other in Saline County, about 15 miles to the southwest. The deposits in both districts are associated with hills of nepheline syenite, bosses of a large batho¬lith that was intruded into Paleozoic rocks and later buried beneath coastal plain sediments deposited during Cenozoic time. The folded Paleozoic rocks are exposed in the northwest half of the state and are covered in the southeast half by the nearly flat-lying coastal plain sediments. The older rocks were intruded by nepheline syenite, probably in Late Cretaceous time, and sub¬sequently were eroded so as to expose the top of the batholith. In Paleocene time, marine limestone and laminated black silty clay of the Midway group were deposited in an advancing sea, and covered all but the most elevated parts of the batholith. Erosion of the islands of nepheline

Jan 1, 1952

By Q. F. Wang, M. H. Lai, T. Q. Liu, G. G. Dong

Compared with the traditional pre-treatment process, biological oxidation process has many advantages including higher gold recovery, less cost, easier operation. The bio-oxidation reactor is the most important equipment for biological oxidation process. In this paper, the characteristics of biological oxidation are investigated, and the design principles are proposed based on laboratory tests. Both increasing the tank height and taking new inflation system can enhance higher dissolved oxygen. The new type of large-scale industrial bio-oxidation reactor is designed, which is 9.5 m in diameter and 10 m in height. The bio-oxidation reactor metallurgical performance has been tested by industrial-scale experiment. The slurry of flotation concentrate is divided into two parts to feed two bio-oxidation reactors. The feeding rates of two reactors are adjusted on the basis of getting the same content of S, Fe, As in overflow. The result shows that the feeding rate of the new type of 700 m3 bio-oxidation reactor is 3.72 m3 per hour, and the feed rate of the conventional 700 m3 bio-oxidation reactor was 3.23 m3 per hour. The processing capacity of the former is 15.2% higher than that of the later, which demonstrates the new type of bio-oxidation reactor has higher oxidation rate.

Jan 1, 2015

By S Long, A J Koen, D MacKay

The Mt Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Following the evolution of the mine plan through a number of stages, the ‘sublevel shrinkage (SLS) with continuous fill’ mining method was implemented in 2010 to extract the Mt Wright orebody. The production front in this mining method is similar to a sublevel cave (SLC) operation; however, backfill is placed into the top of the production zone as opposed to requiring the overlying strata to cave.Continuous fill to replace the void created by extracting the ore was required to manage the potential risks associated with the proximity of infrastructure to the footwall, associated long-term stability and air blast potential due to the limited ‘cavability’ of the material within the cave zone. The available fill material was sourced from a disused waste dump from a previous open pit operation, which introduced further technical and economic risks associated with dilution from ‘no grade’ broken material. Procedures and processes to manage these risks have been incorporated into the operation of the mine.Despite encountering a number of challenges, the SLS method has been in use for approximately three years at Mt Wright and has proven to be viable economically, technically and operationally. This paper will discuss the challenges encountered and what was done to overcome them, the operational and financial performance to date, along with the outcomes of some successful continuous improvement projects that have improved the efficiency of the operation.CITATION:Mackay, D, Long, S and Koen, A J, 2014. Sublevel shrinkage – the Mt Wright story, in Proceedings 12th AusIMM Underground Operators’ Conference 2014 , pp 205–216 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 24, 2014

Epicentres of recent shallow earthquakes in the region (3-12¦S, 126-150`E) were plotted to identify the various plate boundaries in the region, in particular the southernmost one marking the northern edge of the Australian plate. New and published fault plane solutions were examined to determine the style of faulting and state of stress along the Australian plate boundary. From east to west the boundary is first a subduction zone along the Solomon Islands, then a spreading centre across the Solomon Sea, a zone of compression and left lateral strike slip along the Papua Peninsula, almost pure thrusting across the centre of New Guinea and lastly left lateral strike silo through Irian Taya to the outer Banda Arc. The principal stress is very consistent, trending NW to NNW in a near horizontal plane, from the triple junction of the Pacific, Solomon Sea and Australian plates in the east to the Banda Sea in the west. Only along southern Solomon Sea plate margin which is a divergent boundary, is the stress different in type and direction.

Jan 1, 1987

By E. P. Klier, Taylor Lyman

THE structures formed when austenite is quenched to subcritical temperatures and allowed to transform isothermally have been the subject of intensive study since the work of Davenport and Bain.1 Isothermal transformation diagrams summarizing the results of many of these studies have become widely familiar to metallurgists. Of particular interest to metallographers are the dark-etching, acicular products of transformation formed by isothermal reaction below the temperature of maximum velocity of the austenite to pearlite reaction. These products, the bainite structures, can be formed in a wide variety of steels. However, the constitution of bainite is not well understood and divergent views have been expressed as to its mode of formation. In this investigation a combination of dilatometric, microscopic and X-ray methods has been brought to bear upon the problem in the hope of some elucidation of the bainite reaction as it occurs in hypoeutectoid steels. MECHANISM OF BAINITE FORMATION Davenport and Bain1 considered the mechanism of bainite formation to consist of two steps-an allotropic transformation followed by precipitation of carbide. The separation in time of the two processes was considered to be very slight in the upper temperature range and very marked at temperatures just above the martensite range. This concept has been restated by Vilella, Guellich and Bain2 in the form of a definition of the acicular mode of transformation as: The successive, abrupt formation of flat plates of supersaturated ferrite along certain crystallographic planes of the austenite grains; this supersaturated ferrite begins at once to reject carbide particles, (not lamellae), at a rate depending upon temperature. In effect, this is the acicular mode of transformation, even though the temperature be such as to limit the actual life of the quasi-martensite to millionths of a second. The investigation of isothermal decomposition of austenite in certain alloy steels (notably those containing chromium or molybdenum) has revealed that there may be a range of temperatures between the pearlite and bainite reactions in which the austenite decomposes at a relatively low rate.3-6 Further, it is characteristic that in the second region of fast reaction the decomposition of the austenite is incomplete by one reaction but goes to completion by a second reaction. These observations led Wever7 to a description of the bainite reaction as follows: I. The reaction takes place by initial precipitation of a martensitic intermediate structure. 2. In the upper temperature range this structure readily decomposes into ferrite and cementite. In the lower range carbon separates in an unknown form. 3. In the upper temperature range the precipitated carbide nucleates the precipitation

Jan 1, 1944

By J. Mullins

Coal was first banked by the Dominion Coal Company, Limited, in 1898, near No. 2 Colliery, the same site as is presently used for that purpose. Though today there are banks at Glace Bay, Sydney, and Sydney Mines, these notes, except when otherwise desirable, will be confined to describing the practice as developed at the No. 2 Banking Station, Glace Bay, as being typical of methods obtaining at all sites. Storing The manner in which the coal was piled is illustrated diagrammatically in the accompanying sketch. A train of coal was brought on the main trestle, which extended the full length of the banking ground at a height of 22 to 39 feet above the natural surface, and dumped into bins which were integral with the trestle work. Chutes from these bins permitted the coal to be fed into 3-ton cars, which were horse drawn laterally on narrow gauge tracks laid about 10 ft. centres, to a maximum distance of 400ft. from the trestle. These cars were end-dump and as the pile extended laterally the narrow gauge tracks were lengthened by shorter or longer filling pieces, so that their ends were always kept at the brow of the bank. Much coal, however, had to be dumped directly on the tracks and hand trimmed to fill the valleys, and level off, between the tracks.

Jan 1, 1931

By J. Th. G. Overbeek, R. Schumann, P. L. De Bruyn

THE technique of concentrating valuable minerals from lean ores by flotation depends upon the creation of a finite contact angle at the three-phase contact, mineral-water-air. If the mineral is completely wetted by the water phase, contact angle zero, there is no tendency for air bubbles to attach themselves to the mineral. However, when the contact angle is finite, the surface free energy of the system, water-air bubble-mineral particle, can be diminished by contact between the bubble and the particle, and if not too heavy the mineral will be levitated in the froth. With a few exceptions, all clean minerals are completely wetted by pure water. Thus the art of flotation consists in adding substances to the water to make a finite contact angle with the mineral to be floated, but to leave the other minerals with a zero contact angle. The contact angle concept and experimental measurements of contact angles have played important roles in flotation research for several decades.1-3 Nevertheless, there remain unanswered some basic questions as to the scientific significance of the contact angle and the nature of the processes by which flotation reagents affect contact angles.

Jan 5, 1954