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By Alla D. Mah

The heat of combustion of aluminum carbide (Al, C3 ) , obtained directly by combustion calorimetry , was AH298.15 -1,029.6 ± 1.9 kcal / mole . == The heat of formation of aluminum carbide corresponding to this value was AH298.15 = -53.4 ± 2.0 kcal /mole .

Jan 1, 1964

By J. H. Frye, R. M. Treco

ONE of the chief hindrances to an understanding of the hardness of solid solutions is the sparsity of suitable hardness data. There is great need of a large body of hardness data obtained from many different alloys of high purity by identical testing methods and corrected to correspond to a single grain size. A considerable amount of such data has been obtained by means of the Meyer analysis on copper-rich and silver-rich solid solutions. There are enough of these data to permit comparison of numerous alloys at equal solute concentration in these two solvents, but only in a few cases is it possible to construct hardness-concentration curves for any given alloy. Therefore additional hardness work on most of these alloys is desirable. The primary solid solutions of silver with cadmium, indium, tin, or antimony as solute are of special interest, since all elements are from the same period of the periodic table and since, as shown previously,1 the hardening effect of equal percentages of these solutes is proportional to the lattice expansion produced by them. This paper presents the relation between hardness and concentration in the silver-antimony system from very dilute to nearly saturated solutions of antimony in silver. EXPERIMENTAL PROCEDURE Alloys were made from silver, 99.99 per cent pure, and antimony, 99.975 per cent pure. Silver and antimony were placed in graphite crucibles that had an ash content of less than 0.75 per cent. These metals were melted and allowed to solidify in a vacuum, which, after melting was complete, was usually equivalent to 3 mm. Of mercury. A high-frequency furnace was used. The ingots so obtained were worked and annealed to lessen segregation and to control grain size. Annealing was done in evacuated and sealed glass tubes. Hardness measurements on specimens from these ingots were by means of the Meyer analysis.3,4 Using a 4-mm.. ball, impressions were made under seven loads from 25 to 400 kg. The diameter of impression made under each load was measured. This enabled calculation of the constants in the well-known formula of Meyer. L=ad¬n where L = load, d = diameter of impression, a = a constant, n = a constant The Meyer hardness is defined as P = L/(1/4pd2) or P = 4adn-2/p Meyer hardnesses corresponding to d = 1 and to d = 4 are of especial interest, since the first corresponds to comparatively slight plastic deformation and the second to the maximum plastic deformation producible by penetration of the ball. These

Jan 1, 1944

By J Seccatore, G Sadao, M Cardu, G De Tomi, L Finoti, F Galvão, J Romero Huerta, A Rezende, J Bettencourt

In the mining industry, rock blasting can be considered as the first phase of comminution. The downstream phases of comminution are mechanical, and consist in consecutive stages of crushing and milling for grain size reduction. The total energy of mechanical comminution depends on grain size and on the resistance of the material to grindability. Usually, the first is quantified by the grain size distribution or one of its KPIs (such as the diameters X50 or X80), while the latter by the working index (WI), representing the amount of energy necessary to reduce the size of grains of a determined amount of material to the desired equivalent diameter (usually expressed in kilowatt hours per tonne – kWh/t). It is widely recognised that it is possible to manage the output of a blast in terms of grain size distribution varying specific charge (powder factor – PF) and charge distribution; specific algorithms such as the KUZ-RAM or the SWEBREC have been created to predict such output. It has also been demonstrated how higher PFs weaken the blasted material by creating micro-fractures that reduce its WI. This paper focuses on a related aspect: the influence of charge distribution on the specific comminution energy in crushing and milling. Small-scale blasts have been performed on 14 marble blocks with different PFs and charge distribution. For every PF, charges have been designed to simulate concentrated and distributed geometries. Concentrated charges simulate opencast blasts with large-diameter holes, with large burdens and spacings. Distributed charges simulate bench blasts with small-diameter holes and reduced burden and spacing. Three control blocks have been fragmented by mechanical means for comparison. For every sample the grain size distribution and the WI in ball mill has been determined. Results show the correlations between charge distributions and the specific energy of mechanical comminution in milling. Finally, the opportunity of adjusting charge diameters and distributions in opencast blasts to improve the output of the comminution circuits is discussed.CITATION:Seccatore, J, Romero Huerta, J, Sadao, G, Cardu, M, Galvão, F, Finoti, L, Rezende, A, Bettencourt, J and De Tomi, G, 2015. The influence of charge distribution on the grindability of the blasted material, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 749–754 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

Minerals and Manpower - PRESIDENTIAL ADDRESS given by R. P. Plewman, Pr. Eng., B.Sc. (Eng) (Wits), M.A. (Oxon.) INTRODUCTION What I want to discuss is the future pattern of manpower in the mining industry, and I should like to begin by examining some relevant statistics. There are four areas that must be examined. Firstly, the future rate of production of different minerals must be estimated. Secondly, an assessment must be made of the balance of different mining technologies likely to be used for each mineral. Thirdly, the manpower requirements for each technology must be determined. And, fourthly, the future manpower resources of the country must be explored. NIM report Report No. 1646 Examination of the methods of analysis for calcium fluoride in fluorspar.

Jan 10, 1974

By WILKES BARRE

AS PREVIOUSLY announced, the semi-centennial meeting of the Institute is to be held at Wilkes-Barre, Pa., on Sept. 12, 13, 14, and 15. An interesting program of technical sessions and excursions is now being prepared by the Local Committee. At the time of going to press the program had not been completed in sufficient detail to permit its being pub¬lished in this number. The detailed program will be published in the September MINING AND METALLURGY, which will be printed in time to be distributed before the Wilkes-Barre Meeting. It may be said in advance, however, that the Com¬mittee has progressed so far in its work that we are assured of one of the -most notable meetings the Insti¬tute has held and that members will miss a rare .treat if they do not attend. The many trips and excursions, as well as the banquet, will be -given to the members as a compliment from the members of the Local Com¬mittee. . . The paper by Howard Eavenson on the Lynch Plant of -the United States Coal and Coke Co. will be illustrated by lantern slides and moving pictures. One of the most appropriate discussions will be that opened by Prof. J. F. Kemp on the Stratigraphy of the Anthracite Region; this also will be amply illustrated.

Jan 1, 1921

By John C. Cook

In reasonably dry rock, long-wave radar can theoretically explore to distances approaching 75 meters (250 ft). High-resolution radar reflections have already been demonstrated through 13 m of hard limestone, through 9 to 18 m of coal in place and through 225 m of rock salt, using only low-power experimental radar equipment. Radar reflections have been received through the rock from rough pillar walls, from faults, and from a slim, uncased, vertical drill hole. In three years of intermittent experimentation, the feasibility of rapid radar exploration of large volumes of rock, with portable equipment, in deep, wet workings has been demonstrated. With future, improved equipment the theoretical working range, of the order of 75m, is expected to be attained in most hard rocks. THE TECHNIQUE Fig. 1 illustrates an early "monocycle" radar system (1) set up in a coal mine. This radar equipment is entirely different from that employed for detecting distant objects through the atmosphere. However, the basic principle is the same: a pulse of electromagnetic energy is radiated by the transmitter, a portion is reflected by some "target" object embedded in the surrounding medium and some of this energy is collected by the receiving antenna. In the receiver, the pulse is amplified, is "stretched out in time" by a sampling process, and is displayed on the screen of a cathode-ray oscilloscope. It may also be recorded on paper or magnetic tape. Fig. 2 illustrates a

Jan 1, 1997

By S Bailey

In-field sampling programs generally take time, equating to money, and unless you have an onsite laboratory, you have the issue of having to wait long periods for your data. Until recently, field portable X-ray fl uorescence (FPXRF) analysers, which can help provide instant indicative results, were not able to detect penalty elements, such as Al and Si, or do so reliably enough to act upon.The purpose then of this field test then was to show that the latest FPXRF devices are capable of producing reliable readings on field samples of variable grain size, in particular for Al and Si, such that the readings still correlate well with the assay for those samples and thus be reliable for an iron ore grade control application.We tested RC chip samples on-site in the Pilbara, Western Australia, with the Niton, analysing for a range of elements including Fe, Mn, Al and Si and then compared the results for those elements against assay data for the same. A strong correlation would tell us that the FPXRF results were reliable. Furthermore, to show the effect of simple sample preparation, we also analysed pulps of the same samples in the same way.The correlations were good for the all of the four elements of interest for the RC chip samples (R2 values between 0.82 and 0.9), and excellent for the pulps (R2 values between 0.89 and 0.998).The results also showed a direct correlation between sample preparation and improved quality of results with the FPXRF.The data showed allowed for two conclusions:1. the FPXRF can produce data from unprepared RC chips for Al and Si that, when compared with assay, is reliable for a fi eld application in drilling and grade control; and2. the greatest limitation to data quality is sample preparation.

Jul 11, 2011

By Alim Gül, Güven Önal

"Recently, there have been some attemps on the treatment of low grade ores and old plant tailings due to the decrease in high grade ores and the increase in the metal consumption with increasing world population. Cost of mining and beneficiation of low grade ores become prohibitive since the costs of grinding before flotation make the process unfeasable. Therefore, preconcentration of these ores prior to flotation becomes more important. The concentration of ores preconcentrated in coarse sizes provides a decrease in investment costs as well as grinding and flotation costs. Additionally, the requirements of less space for tailing disposal and less reagent consumption are also important from the viewpoint of environmental considerations.In this study, ore sample containing 0.6 % Cu and taken from Küre-Asiköy ore body was used. Ores contained chalcopyrite and pyrite as main minerals and diabaz, quartz, chlorite and sericite as gang minerals.Samples were all crushed under 9 mm by considering the preliminary studies and float and sink experiments were carried out with the sample in the size range of –9+1 mm using different densities of heavy liquids. As a result of these tests, it was shown that 60 % of the material should be discarded as tailings with 0.1 % Cu content. By considering float and sink test results, the following experiments were performed by using heavy medium cyclone and jigs.As a result of heavy medium cyclone tests, which are conducted on the sample in size range of –9+1 mm, 57 % of the feed material was discarded as tailing with 0.08 % Cu content and 7 % Cu loss, while a concentrate containing 1.43 % Cu was produced with 93 % efficiency (Table 1). Jig tests were done with the samples in the size range. As a result of jig tests with –9+1 mm size group sample, approximately 46 % of feed material was discarded as tailings with 0.13 % Cu content and 10.6 % Cu loss, while a concentrate with 0.94 % Cu content was obtained (Table 2)."

Jan 1, 2003

By Seth T. Reese

THE INJURY DATA and experience at coal mines in the United States for 1951 are presented in this bulletin under the following general heads: (A) General injury experience: Tables 1 to 18: Contain current data on number of fatalities and nonfatal injuries, frequency and severity rates, average severity, major and detailed injury agencies, and distribution of injuries by part of body and days of disability. (B) Selected injury data: Tables 19 to 43: Contain current data on various selected factors of operating and physical conditions that contributed to the occurrence of injuries at bituminous-coal, lignite, and anthracite mines. These factors include extent of hand and machine loading, size of mine by employment and production groups, thickness of bed or vein, duration and number of work shifts, rating of mine as gassy or nongassy, types of cap lamps, explosives, and combination of factors that influence mine safety. (C) Injury experience by States: Tables 44 to 50: Contain current data on number of fatalities and nonfatal injuries, frequency and severity rates, average severity, major causes and principal agencies, injury records of all coal-producing States, and the relative standing by States according to injury-frequency rates. (D) Major disasters: Table 51: Lists the coal-mine disasters that occurred during 1951, giving location, source, and cause. A major disaster in coal mining is defined as a single accident in which or as a result of which five or more men lost their lives. (E) Historical coal-mine injury experience: Tables 52 to 86: Contain data on injuries, injury-frequency rates, employment, and production at bituminous-coal, lignite, and anthracite mines from the earliest records through 1951.

Jan 1, 1955

By Lena Paar

"Underground construction poses certain challenges for all parties involved because the actual ground conditions are often unpredictable. Highly complex projects like tunnel construction are affected by various uncertainties. To address this complexity, the construction contract has to be flexible enough to be adapted to the actual conditions (e.g. divergent ground conditions, work delays). However, the adaptation of a tunnel construction contract does not guarantee the absence of a margin of interpretation. The perfect construction contract is an illusion because ex ante statements of the actual ground conditions are not feasible. This paper will discuss contractual parameters that must be considered in order to enable an effective adaptation of the contract during excavation. It is therefore necessary to discuss the following topics: decision-making competence, variable remuneration, fair-risk allocation, value engineering and partnering between client and contractor. INTRODUCTION Thinking of tunnel construction processes, engineers’ first (or at least second) association is about ground conditions. When constructing under the surface, the project is directly related to the ground conditions; however, ground conditions are known fairly well in advance. The estimated conditions can be the same or can also differ from the existing ones. A clear view of the conditions is possible only by driving through the section. What Hoek calls “Geological unpredictability which is guaranteed to provide some surprises in even the simplest tunnelling job” is, in addition to contractual issues, one of two critical aspects of modern tunneling (Hoek 1982). Almost no research tries to figure out, what flexibility in this context means and how to approach it in the contracts. Papers dealing with the New Austrian Tunnel Method (NATM) pose some principles to meet the requests for flexibility (cf. Austrian Society for Geomechanics 2011). However, it remains unclear how to create contracts in order to make them “flexible” enough to react to divergent ground conditions."

Jan 1, 2016

By John Pekrul

Coeur Rochester Inc. located in north central Nevada, operates an open pit mine moving a total of 16 - 18 million short tons of material per year. A three stage crusher produces approximately 8 million tons of a minus half inch product that utilizes truck stacking to construct a heap leach with a zinc precipitation recov­ery plant. Coeur Rochester recovers approximately 6.0 - 7.0 MM ounces of silver and 60 - 80 K ounces of gold annually. Current metal prices and good operating practices require contin­ued review of operating systems that support the operation, thus the development of a Strategic Mine Plan. This Strategic Mine Plan provides managers, engineers and supervisors a means to improve their operations through three main objectives: 1. Reduce operating costs, 2 .. Increase production, 3. Increase mine life (reserves). These three main objectives will be reviewed in context to their current status and past performance.

Jan 1, 1999

By K. A. Kiselev, V. I. Zelentsov, V. P. Nebera

INTRODUCTION Most works on flotation of ions and precipitates from solutions have been summarized recently (1-3). Flotation is more desirable than thickening or centrifuging because of higher recovery, productivity, simplicity of apparatus and better economics in general. Electrolytic flotation that utilizes gases is more favorable than other flotation processes because of the following: higher dispersity of gas bubbles, low coalescence of the bubbles, possibility of gradual regulation of the dispersity and other parameters of flotation (4-5). Flotation from solutions is mostly based on the use of alkaline reagents as precipitants (5). Flotation from acid solutions is less common. We used multicomponent solutions with more than 2-3 components, unlike previous research methods. Acidic flotation allows recirculation of solutions to previous operations such as leaching, etc. REAGENTS FOR PRECIPITATION Electroflotation was studied over a wide range of pH with the addition of ferrocyanide, oxyquinoline, hydroxide and carbonate precipitants. In recent works (1,2,6,7) on flotation of Ni, Cu, Zn from alkaline solutions, mostly ferrocyanides were applied. Our choice was oxyquinoline because of the following: 8-oxyquinoline is a nonspecific reagent for many metals, it is readily soluble in acids and alkalis, oxyquinolates of the studied metals are in soluble compounds, the reagent works over a wide range of pH, it is widely available, oxyquinolate precipitates are stable when exposed to air, are readily floatable, and are easily converted to oxides of the metals by sintering.

Jan 1, 1980

By L. J. E. Hofer

THIS BULLETIN analyzes and summarizes research at the Bureau of Mines dealing with the preparation, properties, and reactions of iron carbides in the period 1948-60, part of which was sponsored by Wright Air Development Laboratories. The objective was to develop better catalysts for the synthesis of methane and higher hydrocarbons from hydrogen and carbon monoxide. The investigations resulted in the first adequate characterization of epsilon iron carbide, which later proved to be an important intermediate in the tempering of martensite in steel. At temperatures near 170° C, the carbon in carbon monoxide reacts nearly quantitatively with finely divided alpha iron to form an iron carbide in which the metal atoms occupy the positions of the close packed hexagonal arrangement with lattice parameters of ao=2.754 A and co=4.349 A. The carbide has a composition within 2 atomic percent of that required for the formula Fe2C, a Curie point of about 370° C, a specific magnetization of 160.4 ergs per gauss-gram Fe at 50° C, and a ferromagnetic moment of 1.70 Bohr magnetons. Epsilon iron carbide can be converted to chi iron carbide by thermal treatment at 343° C for about 70 hours. The chi iron carbide so formed has a Curie point of 247° C, a specific magnetization of 142.5 ergs per gauss-gram Fe at 50° C, a ferromagnetic moment of 1.72 Bohr magnetons per iron atom, and a paramagnetic moment of 5.5 Bohr rnagnetons per iron atom. Direct synthesis of this carbide from carbon monoxide at 240° C indicates a composition within 7 atomic percent of that required for Fe2C. Chi iron carbide can be converted to cementite at 550° C in about 315 minutes. The theta iron carbide so prepared has a Curie point of 210° C, a specific magnetization of 147.3 ergs per gauss gram Fe at 50° C, a ferromagnetic moment of 1.72 Bohr magnetons per iron atom, and a paramagnetic moment of 3.9 Bohr magnetons per iron atom. Pure chi iron carbide reacts to form theta iron carbide by the elimination of free carbon. In the presence of an excess of free iron in intimate contact with the carbide, chi iron carbide reacts with the free iron to form theta iron carbide. The second reaction proceeds at an appreciable rate at 320° C and can be used to snythesize finely divided theta iron carbide with no free-carbon impurity at low temperatures. The ease of the reaction in the presence of free iron suggests that chi iron carbide is an intermediate in the tempering of epsilon iron carbide to theta iron carbide as it proceeds in steels. Experiments on carbon steel show that the magnetic moment of the iron atoms in martensite is about 2.2 Bohr magnetons per atom, a value approximately the same as that of the iron atoms in alpha iron. The Curie points of epsilon iron carbide, chi iron carbide, and theta iron carbide were found -in various specimens of tempered steel to be 10° to 20° C lower than normal values. This shift is probably the result of manganese in solid solution. Preparations of various compositions of epsilon iron carbonitrides show many effects of extensive isomorphism between epsilon iron carbide and epsilon iron nitride. The action of carbon monoxide on finely divided alpha iron at 400° C results in free carbon deposits containing filaments about 0.1 micron in diameter and several times as long. The filaments are characterized by nuclei of dense material located midway from each end of the filament. Although carbiding to near completion at 240° C over periods of about 300 hours produces a preparation containing no appreciable percentage of epsilon iron carbide, very brief periods of carbiding of the order of a minute result in the formation of detectable epsilon iron carbide even at temperatures as high as 325° C. The data indicate that epsilon iron carbide is an intermediate in the formation of chi iron carbide during its formation from carbon monoxide in the gas phase. Attempts to convert cementite to chi iron carbide by cold work increased the Curie point but did not change the X-ray powder diffraction pattern.

Jan 1, 1966

A strategy is presented for a relatively. "low-tech" means for decontamination of streams . containing .low concentrations of toxic metals. Metal ion solutions were . circulate through fluidized beds of activated carbon which support bio-films ?of bacteria .that naturally excrete exopolysaccharides. The attached 'biomass is shown to significantly enhance nickel, cadmium and silver extraction from dilute solutions (5- l00mg/l). By heat treating (at 300º C) the metal/biomass/carbon particles, bio-sorbed silver was subsequently fixed to the carbon surface. This approach to metal decontamination may therefore also provide a route for dispersing and fixing catalytic metal particles over an activated carbon surface.

Jan 1, 1991

The Thirty-third Regular Meeting of the Rocky Mountain Coal Mining Institute was called to order at 11: 10 o'clock A.M., Monday, March l8th, 1935, President H. H. Bubb presiding. On motion of Gilbert Davis, duly seconded, it was voted that the reading of the minutes be dispensed with, inasmuch as they are printed in the proceedings. Owing to the absence of Mr. H. C. Marchant, who was unavoidably detained in Washington, Mr. F. W. Whiteside, Secretary Pro Tem, made the annual reports of the Secretary-Treasurer, which, on motion duly made and seconded, were received."

Jan 1, 1935

By R. W. Raymond

Samson Jordan was born at Geneva, Switzerland, June 23, 1831. At the age of 20 years he entered the Ecole Centrale des Arts et Manufactures, at Paris, from which he was graduated with high honors in 1854. After some months of service with the Compagnie du Chemin de Fer du Nord, he was employed (upon the recommendation of his former instructor, Prof. Burat, who had recognized his remarkable ability) at the mines of Portes, belonging to the Société de l'Elairage au Gaz et des Hauts Fourneaux, etc., of Marseilles, and subsequently to construct the St. Louis iron blast-furnaces of that Co. After finishing this work, he remained at Marseilles as a member of the directory of the Co., particularly connected with the development of its mines. In 1862 he became the general advisory engineer of the Co., and still later (1873) its general manager (Administratet~r), a position which he retained until his death, February 24, 1900. He became subsequently Administrateur of other important French industrial enterprises, including those of the Compagnie des Naut Fourneaux, Forges et Aciéries de Denain et Anzin, and the Compagnie Banco-Belge des Mines de Somorrostro ; and he was also, at various times, President of the Société technique du Gaz, Vice-President of the Comité des Forges de France, mepber of the Council of the Société d'Encouragement pour l'Industrie nationale. In all these positions, it is the unanimous testimony of his colleagues that he was no mere ornamental figurehead, but a profoundly wise, practical and industrious laborer and adviser, both patient and keen in the mastery of details, yet at the same time competent to apprehend the wider bear-

Jan 1, 1902

By John A. Cherry

Groundwater monitoring conducted at an acidic uranium-tailings impoundment in Wyoming and at one in Ontario indicate that at these unlined impoundments situated on unconfined sand aquifers, there exist well-developed plumes of contaminated groundwater. In the literature similar results are reported for three other unconfined aquifers at mill sites in Wyoming. The plumes extend for distances of several hundred to a few thousand metres from the impoundments. They have a zone of low pH beneath and adjacent to the impoundments and a larger zone of near-neutral pH that extends to the outer limits of the plume. The low-pH zones are generally small compared to the neutral-pH zones because the advance rate of the fronts of acidic tailings-derived water is slower than the average velocity of groundwater which controls the advance of the high pH zone. The retardation of the acid fronts is a result of geochemical reactions that cause hydrogen-ion consumption in a slowly-advancing neutralization zone. Within each of the plumes, the low-pH zone has high concentrations of transition metals, heavy metals and radionuclides. In the neutral-pH zones all of the metals and radionuclides occur at significantly lower concentrations and are generally at levels much below those specified in national drinking water standards. An exception at two of the Wyoming sites is uranium, which exists at levels close to the drinking water limit. A second exception is ferrous iron at the Ontario site, which occurs at high concentrations throughout most of the plume. The carbonate alkalinity at this site is much lower than at the Wyoming sites. The field data indicate that even in very permeable aquifers with a low content of silt and clay, there is normally a considerable capacity for acid-front retardation. To take advantage of this capacity to control contaminant movement in the design, operation and decommissioning of tailings impoundments, it is necessary to be able to predict the rate of acid-front movement. This predictive task has two primary components. The first is to identify the important flow paths from the tailings through the groundwater system and the second is to determine the degree of acid-front retardation that will occur as the tailings-derived water moves along these flow paths. Relative to these two tasks determination of the effects of hydrodynamic dispersion is generally of lesser importance and simple approximations that do not involve field or laboratory tests are probably adequate. In order to effectively apply the acid neutralization concept to the prediction of subsurface contaminant migration at uranium-mill tailings, improved representations of hydrogeochemical behavior of iron and aluminum in the neutralization zone and of the consumption of hydrogen ions through reactions with carbonate and aluminum-silicate minerals are required. Along with the hydrogen ions contained in the tailings water the ferrous iron represents a large potential source of acid but the extent to which ferrous iron converts to ferric iron to produce acid is problematic. Detailed hydrogeochemical evaluation of existing contaminant plumes and the performance of laboratory experiments under appropriate redox conditions ore prerequisites for the improvement of predictive models. However, the existing field and laboratory data provide a basis for preliminary predictions of contaminant migration from acidic uranium tailings impoundments.

Jan 1, 1982

By Bastiawarman Rifki, Nugraha Nico, Priatna Anton

The Deep Mill Level Zone (DMLZ) is one of the underground mines operated by PT Freeport Indonesia (PTFI). DMLZ is located approximately 1,500 m below ground level, where dominant rock types are skarn and diorite. The DMLZ mine and layout was designed based on the previous mine located above ground, the Deep Ore Zone (DOZ). The DOZ mine, located approximately 1,000 m below ground level, was a proven success, with a maximum capacity of 80K tonnes per day. During the production ramp up, which started in 2015, the DMLZ experienced several seismic events. The most significant event occurred in January 2018 with a recorded magnitude of more than 2.0 Mw, which resulted in a 14-month delay of the undercutting until March 2019. The significant event in January 2018 required the DMLZ to apply several adjustments related to the mining plan to help ensure it could continue development and achieve production target safely. This paper will describe the changes in the DMLZ mine plan as a response to the seismic activity at the mine, the reason behind the decisions being made to change the mine plan and strategy, as well as strengths and weaknesses between the previous plan compared with the new plan.

Apr 26, 2022

By NEWTON B. KNOX

THE war has forced the principal industrial nations of the' world into the strait jacket of a closely controlled economy; taxes have been heaped upon all enterprises in order to maintain the armed forces and to deprive the people of the ability to bid for goods now unavailable. These restrictions, controls, and taxes are unlikely to disappear entirely after the war has been won, for debts will remain to be paid with a long period of difficult readjustment. Although the new economy will doubtless offer plentiful opportunities for the advantageous use of capital, no investor can ignore the favorable conditions offered by industry in Latin America, where taxes are relatively low and the restrictions on free enterprise comparatively mild. In mining in South America, the great international corporations have

Jan 1, 1944

This data is intended to provide a quantative cost comparison of one 40 800 kg. pull down rotary blast hole drill versus two smalter drills in the 18 100 kg. pull down class. While this cost analysis is affected by blast design, this paper is not intended to be a treatise on blasting theory and therefore places more emphasis on costs than on blast design. All costs, prices and production rates in this paper are estimates and should be used for comparison purposes only. The drills are sized in order to maintain a production rate sufficient to stay ahead of a dragline that is excavating in an average overburden (sandstone and shale). The large drill will use 270mm bit and penetrate at a rate of 0.012 m/s (scheduled basis). The small drill will use 170mm bit and penetrate at a rate of 0.010 m/s (scheduled basis).

Jan 1, 1986