Search Documents

By Benjamin W. Haynes

The Bureau of Mines conducted research to provide technical information needed to devise waste management plans for the processing of manganese nodules. Studies included summary descriptions of Pacific manganese nodules, process options and flowsheets, methods for characterizing nodules and their tailings, and results of analyses of laboratory and pilot-plant generated tailings. This information is the result of a cooperative research effort of the Bureau of Mines and the National Oceanic and Atmospheric Administration (NOAA), with NOAA providing funding and the Bureau conducting the research. A summary of the extensive literature review is provided for manganese nodule mineralogy, chemistry, processing techniques, and methods of analyses. Characterizations and analyses of laboratory-generated tailings and slags are given, as well as the results of the leaching studies on these waste materials. Leachability was determined by three standard leachate tests- the Environmental Protection Agency (EPA) extraction procedure (EP) toxicity test, the American Society for Testing and Materials shake extraction test, and the U.S. Army Corps of Engineers-EPA seawater elutriant test. While the wastes generated in the laboratory may not be entirely representative of those to be generated in full-scale plants, results of these studies provide a positive indication that commercial recovery of cobalt, copper, manganese, and nickel from manganese nodules would be environmentally acceptable.

Jan 1, 1985

By AUDLEY H. STOW

I. INTRODUCTION. THE general drift of the discussion as to the relative merits of pressure- and exhaust-fans has resulted, if we may judge from the prevailing practice, largely in favor of the latter. The subject has been hitherto treated, however, with special reference to highly gaseous mines, the effect of the form of ventilation upon dust-explosions having been too little considered. Even in mines containing practically no gas, dust-explosions may occur; and if, as I believe, pressure-fans are to be preferred for their effect upon dust, it may be worth while to reopen the debate, and to challenge the advisability of exhaust-ventilation under certain conditions. There are several forms of colliery-ventilation, which may be described as follows: Plain or simple pressure-ventilation, in which the fan acts as a pressure-fan, and the movement of coal is unobstructed at the surface by doors or equivalent devices in drifts or shafts, the traveling and haulage thus being in the return-current. Plain exhaust-ventilation, in which the fan acts as an exhaust-fan, the movement of coal being likewise unobstructed at the surface, and the traveling and haulage being in the intake. Obstructed pressure-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the intake. Obstructed exhaust-ventilation, in which the movement of coal is obstructed at the surface, in order that the traveling and haulage may be in the return. The apparent advantages in running a fan "pressure" during working-hours, and " exhaust" between shifts, seem to justify the recognition of this combination as a standard form of ven-

Feb 1, 1909

By James Westfield

Following is a resume of activities of the Division of Coal-Mine Inspection that have had a favorable effect on health, safety, and the reduction o1 injuries at coal mines: 1. The Federal Mine Safety Code for Bituminous Coal and Lignite Mines of the United States was issued originally by the Director of the Bureau of Mines July 24, 1946, after consultation with management and labor representatives of the coal-mining industry. The code has been used by Federal coal-mine inspectors while inspecting bituminous coal and lignite mines as a basis for determining the existence of unhealthful and unsafe conditions and practices in these mines. A revised code was issued by the Secretary of the Interior October 8, 1953, after further consultations with representatives of management and mine workers and was incorporated by reference in the 1952 and subsequent bituminous coal wage agreements. The agreement of May 29, 1946, between the Secretary of the Interior, acting as Coal Mines Administrator under authority of Executive Order 9728, and the United Mine Workers of America, covering bitumi¬nous coal and lignite mines in Government possession, charged Federal coal-mine inspectors with the responsibility of making periodic investigations of the mines and reporting to the Coal Mines Administrator any violations of the Federal Mine Safety Code. Federal coal-mine inspectors also had temporary authority to close mines found to be imminently dangerous, but such authority (under Executive Order 9728) was removed June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1959

By Kim Appleby

Epithermal gold-silver (lead-zinc-copper-manganese) mineralization on Misima Island is confined to steep and reactivated flat-lying normal faults in the upper plate of a major, shallowly dipping detachment fault. The hangingwall comprises an Eocene metavolcano-sedimentary sequence that has been extensively intruded byMiocene calc-alkaline granodiorite. It is unconformably overlain by Pliocene sedimentary and volcanic rocks. High-pressure amphibolite facies rocks dominate the footwall and have many characteristics of a metamorphic core complex. Mafic-alkalic lamprophyre dike swarms intrude the hangingwall and footwall sequences. Previous workers attributed the gold-silver mineralization on Misima to the intrusion of the porphyritic granodiorite (Williamson, 1984). This has been proposed for many tertiary gold deposits of the southwest Pacific(Sillitoe, 1989; Leach and Corbett, 1994).

Jan 1, 1996

By VIVEK KUMAR HIMANSHU, M. P. Roy, P. K. Singh, A. K. Mishra, RAVI SHANKAR

Blasting with the aim to reduce oversize boulders in underground has many hurdles due to limited accessibilities and poor site conditions. Optimized drilling and blasting parameters can help to achieve this objective. The major challenges of the blast designers lie within deciding blast geometry, namely drill hole diameter, burden, and spacing. The general approaches covered worldwide to determine burden-spacing are based on various rules of thumb, which are based on previous experiences of blasts and the associated outcomes. However, many parameters influencing optimum burden-spacing to achieve desired fragment size are site specific. Sometimes drill geometry is decided based on associated blasting hazards rather than rock fragmentation. The Kuz–Ram model is a worldwide accepted rock fragmentation predictor. The parameters associated with this predictor also include burden-spacing for a blast. Back calculation of burden-spacing from the Kuz–Ram model can be used to achieve desired fragment size. This paper deals with burden-spacing determination by using an empirical approach for the underground stope ring blasting.

Jan 4, 2020

By Fabio Santillán, Mario Mauro, Raffaella Granata

"This paper presents the utilization of slurry walls methods for the recent remediation of three high hazard active dams in the United States. Tuttle Creek Dam, located in Manhattan, KS, required seismic retrofit. To this extent, transverse shear walls were installed on the downstream slope using self-hardening slurry (SHS) to reinforce the liquefiable foundation soils. Herbert Hoover Dike, located around Lake Okeechobee, FL, is subject to potential failure because of internal erosion, piping and slope instability at high water levels. The innovative use of the hydromill equipment with SHS allowed the successful construction of the cutoff wall through heterogeneous soils and rock. At Bolivar Dam, located in Bolivar, OH, under-seepage negatively affects the structural stability of the dam, and a partial seepage barrier wall is required through the upstream slope of the dam. In this case, the Contractor selected the plastic concrete seepage barrier, excavated by a combination of clamshell and hydromill equipment. The main features of the three projects are summarized in Table 1. IntroductionTuttle Creek Dam was constructed by the U.S. Army Corp of Engineers (USACE) on the Big Blue River in North-East Kansas in the 1950s for flood control. Tuttle Creek Dam is a zoned earthfill embankment, 7,500 ft long and about 137 ft high with a crest width of 50 ft (Fig. 1). It is located in an area of moderate seismicity associated with an old continental rift zone located just to the east of the dam. The USACE, under the Dam Safety and Assurance Program, determined the need for remediation. Site investigations and geotechnical analyses identified the upper alluvial foundation sands as being susceptible to liquefaction when subjected to the Maximum Credible Earthquake.In 2005, USACE awarded a construction-manager-at-risk/early Contractor involvement contract. The USACE and the Contractor closely cooperated to identify the most effective technologies, materials and configurations to be used in the remediation. The original remediation design required both the upstream and downstream slope stabilization of liquefiable foundation. Results of refined seismic deformation analyses revealed that the stabilization of the downstream slope and toe was needed to protect the downstream seepage control system and to provide assurance that a liquefaction-induced flow slide would not occur (Stark et al., 2012)."

Jan 1, 2016

The Interior Department's Bureau of Mines is the Federal Government's primary research arm in the mineral and fossil-fuel fields. In accordance with its Organic Act of 1910, the Bureau's responsibilities have been reinforced since the passage of the Federal Metal and Nonmetallic Mine Safety Act of 1966, the Federal Coal Mine Health and Safety Act of 1969, and the Mining and Minerals Policy Act of 1970. The 1966 and 1969 acts deal specifically with the development of safe working conditions and a healthful working environment for those engaged in the mining industry, while the third sets the national policy as follows: " ... to foster and encourage private enterprise in (l) the development of economically sound and stable domestic mining, minerals, metal, and mineral reclamation industries; (2) the orderly and economic development of domestic mineral resources, reserves, and reclamation of metals and minerals to help assure satisfaction of industrial security, and environmental needs; (3) mining, mineral, and metallurgical research, including the use and recycling of scrap to promote the wise and efficient use of our natural and reclaimable mineral resources, and (4) the study and development of [ ]

Jan 1, 1972

By J. D. de V. Louw

Introduction Zircon is a natural occurring mineral and may exhibit natural low level radioactivity. It contains trace levels (90 to120 pCi/g and 110 to 115 pCi/g respectively or 3.3 to 4.4Bq/g and 4.1 to 4.3 Bq/g) of naturally occurring radioactive uranium and thorium. This mineral is often found in a suiteof minerals (rutile, ilmenite and monazite) Due to the overlap in physical properties of monazite (containing 4–7% thorium) with some of the zircon (slight magnetic susceptibility) it often contaminates the zircon, adding to the levels of thorium in the product. Hazards associated with the products from zircon and its processing is inhalation of respirable dust (generated by milling) containing radioactive uranium and thorium which may cause cancer of the lungs. Legislature regulates the transport, use, workplace environment exposure and storage of radioactive material. In America the general regulation for the unlicensed use of low levels of radioactive materials limits the concentration to 500 ppm (U plus Th). Europe (IAEA) specifies a limit of10 Bg/g (Bequerels per gram) on the parents for transport only which is a higher level of U+Th. Companies selling into these markets need to comply with these regulations and certification is therefore required, not only of the major constituents determining the price, but of the U and Th levels as well. Exceeding the limits for U and Th may result in material being returned to the country of origin. However, for the analyst the requirement is to analyse for these elements throughout the production process as well as the analysis of the ‘tails’ that is returned to the mine area. This requires a wide range of concentration to be analysed. Methods of analysis A wide variety of methods exist for the analysis of U and Th in a range of matrices. (Table I) All these methods have been used with varying degrees of success in terms of accuracy. Overall precision for the different techniques varies from 5 to 25% relative. Time to produce results from these methods vary from a few minutes to several days. The Production Chemist is expected to produce between5 and 10 analyses per hour for process control purposes. A suitable technique that fits this requirement is X-Ray Fluorescence. Both Wavelength Dispersive (WDXRF) and Energy Dispersive X-Ray (EDX) instruments are suitable. X-Ray analysis in general has a few major advantages over competitive techniques. •It is fairly simple to set up and interferences are known and easy to correct •It has multi-element analysis capabilities •Clean spectral lines for U and Th (in zircon specifically) •Uncomplicated and easy to measure background •Low detection limits (3 to 5 ppm) •A very high degree of precision •Sample preparation is uncomplicated and fast (pressed powders and fused beads). In Zircon (ZrSiO4) processed sands the matrix is constant(>99% ZrSiO4) and the background is thus essentially constant. A typical set up for the analysis of U and Th by WDXRFis given below: X-Ray Tube Tungsten (W) Target, 2.5 to 3kW operated at 50mA/50kV Crystal LiF200 (or LIF220 for higher resolution) Analytical Lines (2?)U La1,226.14Th La1,227.47 Detector Scintillation Counter Analysis time, depending on the concentration can vary from as little as 20 seconds up to 5 minutes. Standards As with any other comparative technique XRF analysis relies heavily on the quality of the standards used. Assuming proper set-up and operation of the instrumentation as well as consistent sample preparation, accuracy is determined by the quality of the initial calibration standards. A search for the available zircon certified reference materials (CRMs) shows that there are only a few CRMs

Jan 1, 2003

Systemic process mineralogy study on Baerbulawu refractory hematite ore in Kazakhstan has been carried out. The ore contains Fe 41.34%, and 87.26 % of which exists in hematite. Most hema-tite occurs as fine or ultrafine grains and its average size is only 0.015mm. The gangue is mainly composed of quartz, mica, chlorite, kaolinite and other clay minerals. The liberation of hematite is only 66% when the ore is grinded to 75% ?0.074mm, while part of gangue is already liberated from hematite under this grinding condition, so these gangue can be cast away by magnetic separation in advance. Hematite will not liberate completely from gangue untill grinding fineness reaches 86% ?0.038mm, at the same time, free particles of ultrafine hematite tend to coagulate randomly with quartz and clay minerals, so appropriate dispersant is necessary to pre-vent hematite and clay minerals from coagulation. Based on the process mineralogy research, final technology flowsheet is high-intensity magnetic separation by coarse grinding?rough magnetic concentrate regrinding?inverse flotation, and an ideal index is achieved. The yield of final iron concentrate is 43.46%, and its grade and recovery are 66.76% and 70.55% respectively. The research result is also useful to other similar iron ores.

Jan 1, 2014

By H. W. Page

Petroleum requirements since V-J day have been appreciably higher than predicted. Foreign operations now exceed maximum wartime levels by about 14 per cent. Domestic operations since V-J day have averaged 92 Per cent of the wartime peak. In spite of maximum foreign refinery runs, large exports of all products, except residual fuel oil, are necessary to meet foreign demand. During the next few years it is expected that foreign operations will continue at capacity, including new installations, but that, because of increases in foreign demand, exports will continue at about their present level. Domestic operations will increase during this period and crude production probably will exceed maximum efficient rates. Even after 10 years some exports probably will be required, but eventually these will be supplanted by increased output of foreign refineries, except for small tributary exports. The increase in domestic requirements will exceed the decline in exports. Unless findings of crude oil exceed present expectations, the increasing demand will be met by increased imports and synthetic methods-—such as the Hydrocarbon Synthesis Process for conversion of natural gas and coal to gasoline and distillates. Catalytic cracking installations will increase as crude availability decreases. This will help to meet the increasing demand for gasoline but will intensify the domestic shortage of residual fuel oil. Eventually larger imports will be required to satisfy the demand for this product. Introduction Under the pressure of the wartime period, there was time only occasionaly to look ahead in anticipation of what the postwar era held for the petroleum industry. Perhaps the general expectation was that a rather pronounced decline in the level of industry petroleum operations would take place shortly after the end of the war, with the impact felt mainly on the economy of the United States- It is of interest now, nine months after V-J day, to take inventory of the near-term situation and see what significant forces are at work. With this as a starting point, it should be possible to engage in something more satisfactory than pure speculation concerning trends in the immediate future and 10 to 20 years ahead. Present and Near-term Situation During the nine-month period following V-J day, foreign crude oil production and rebery operations have actually increased the These activities were at maximum capacity on V-J day but the continuation of drilling programs, the completion of new and rehabilitated refineries and of transportation facilities during the Past nine months have increased the foreign capacity. This added capacity has been fully utilized. Foreign crude oil production in May 1946 is about 14 per cent higher than during July 1945 and refining operations some 12 per cent higher' During the same period there has been a falling off in similar activities within the

Jan 1, 1947

By H. W. Page

Petroleum requirements since V-J day have been appreciably higher than predicted. Foreign operations now exceed maximum wartime levels by about 14 per cent. Domestic operations since V-J day have averaged 92 Per cent of the wartime peak. In spite of maximum foreign refinery runs, large exports of all products, except residual fuel oil, are necessary to meet foreign demand. During the next few years it is expected that foreign operations will continue at capacity, including new installations, but that, because of increases in foreign demand, exports will continue at about their present level. Domestic operations will increase during this period and crude production probably will exceed maximum efficient rates. Even after 10 years some exports probably will be required, but eventually these will be supplanted by increased output of foreign refineries, except for small tributary exports. The increase in domestic requirements will exceed the decline in exports. Unless findings of crude oil exceed present expectations, the increasing demand will be met by increased imports and synthetic methods-—such as the Hydrocarbon Synthesis Process for conversion of natural gas and coal to gasoline and distillates. Catalytic cracking installations will increase as crude availability decreases. This will help to meet the increasing demand for gasoline but will intensify the domestic shortage of residual fuel oil. Eventually larger imports will be required to satisfy the demand for this product. Introduction Under the pressure of the wartime period, there was time only occasionaly to look ahead in anticipation of what the postwar era held for the petroleum industry. Perhaps the general expectation was that a rather pronounced decline in the level of industry petroleum operations would take place shortly after the end of the war, with the impact felt mainly on the economy of the United States- It is of interest now, nine months after V-J day, to take inventory of the near-term situation and see what significant forces are at work. With this as a starting point, it should be possible to engage in something more satisfactory than pure speculation concerning trends in the immediate future and 10 to 20 years ahead. Present and Near-term Situation During the nine-month period following V-J day, foreign crude oil production and rebery operations have actually increased the These activities were at maximum capacity on V-J day but the continuation of drilling programs, the completion of new and rehabilitated refineries and of transportation facilities during the Past nine months have increased the foreign capacity. This added capacity has been fully utilized. Foreign crude oil production in May 1946 is about 14 per cent higher than during July 1945 and refining operations some 12 per cent higher' During the same period there has been a falling off in similar activities within the

Jan 1, 1947

The cost of power is an important matter to mining companies generally and this thought that the members of the Australasian Institute of Mining Engineers, as well as the engineering and mining professions generally would be interested in any proposal for the reduction of that cost-has led to the presentation of this paper.The writer trusts that the description will be found clear and increase the interest in this exceedingly interesting subject. In the working up of the electrical arrangements touched on in this paper, the author has had the able assistance of hisfriend Mr. F. J. Mars, to whom he offers his hearty thanks. The selection of the best class of power plant for a mine is a very difficult and large problem and it is quite out of place to dogmatise that anyone of the many systems that offer isbetter than another, eg that the all electrical is better than the partly direct steam-driven and partly electrical, or that a gas plant is better than a steam plant.Such a selection is one that calls for very careful and close consideration, in each particular case, of a large number of regulating factors before it is possible to arrive at a proper decision.

Jan 1, 1911

By W. D. Macleod

This paper describes a mineral dressing process for the upgrading of tin ores. The process described is called 'agglomeration' and. is similar in many respects to flotation. Many variables have been examined experimentally both on batch and continuous operations and are reported upon herein... Using a Mt. Pleasant tin ore, assaying 0.5% Sn, an upgrading to 8% Sn, with a recovery of 95% could be obtained by this process.

Jan 1, 1966

By Gary A. Kingston

This examination of Pacific Northwest (Idaho, Montana, Oregon, and Washington) ferrous scrap-industry operations, principally those in Oregon and Washington, points out factors influencing the supply and consumption of scrap materials, such as the complete dependence of steel ingot producers in these States on scrap as a metal raw material and the sizable quantity of scrap exported from Seattle and Portland to Japan. The pattern of the industry is presented as a movement of materials from their diverse sources to the consuming market. The geographic locations of the consuming industries in relation to the areas generating scrap materials and the movement pattern of the supply from source to destination strongly influences the cost of the commodity. The best measure of the scrap supply available in an area is experience in terms of how much scrap was withdrawn at a given price. Scrap availability is not finite, because the return of materials as scrap is secular and influenced by constantly varying market conditions. Steel ingot producers use 75 percent of the approximate 500,000 tons of scrap consumed in Oregon and Washington; steel foundries take 15 percent of the total; and iron foundries, ferroalloy plants, and other miscellaneous consumers utilize the remainder. Also, from 1955 to 1960 an average of about 200,000 tons has been exported annually from Oregon and Washington. The foreign exports are supplemented by lesser shipments to other steel producing States, principally in the western United States. From 1955 to 1960 the preferred and higher value heavy melting scrap grades accounted for about 60 percent of total withdrawals which varied between 600,000 and 950,000 tons annually. Total crap withdrawals from Oregon and Washington are projected to 1.8 million tons by 1985, 60 percent (1.1 million tons) of which will be heavy melting grades. No. 1 heavy melting scrap is most attractive to scrap consumers at $35 per ton or less. Price-supply relationships compared with projected scrap requirements indicate future prices possibly over $35 per ton. High prices over a long period could motivate the Pacific Northwest scrap consumers to produce steel from iron ore. However, technologic changes taking place at integrated steel plants could reduce scrap withdrawals from the Pacific Northwest, which might keep the scrap price sufficiently attractive to obviate production of competitive iron products by the Pacific Northwest scrap consumers.

Jan 1, 1964

By H. F. Yancey

One of the important duties of the Bureau of Mines is to sample and analyze coals and to publish the results of such analyses for the information of producers, consumers, and the general public. Numerous publications containing such analyses have been Issued from time to time. Although the chemical properties of a coal as revealed by its proximate and/or ultimate analysis and heating value aid one considerably in visualizing its probable behavior and in determining its usefulness and value for a specific purpose, they do not furnish complete information. The physical properties of a coal, such as its ability to retain its original form without undue breakage or degradation in size under the various conditions of storage and usage, are also of importance in determining its suitability, technically or economically, for a given purpose.

Jan 1, 1932

By N. J. Sather

A detailed description is given of Bunker Hill's concentration process employed at the company's lead-zinc property in the Coeur d'Alene district, Idaho. The plant is equipped to process 3000 tpd of Pb-Zn ore. The history of the Bunker Hill mine dates back to Aug. 26, 1885, when Noah S. Kellogg found the outcrop of the Bunker Hill orebody on the hillside of Milo Gulch above the present town of Wardner, Idaho. A small concentrator was erected in 1886, and before the railroad came, the mine output was transported by mule teams to the head of navigation on Coeur d'Alene Lake. After ten years of production, an interest was purchased in the Tacoma smelter at Tacoma, Wash., to which the entire output was shipped. In 1916 and 1917, a modern lead smelting plant and refinery was erected, and a modern electrolytic zinc reduction plant was built in 1927-1928 by the Sullivan Mining Co. which was 50 pct owned (and now totally owned) by the Bunker Hill Co. The first concentrator, a 100-tpd capacity plant, was built in 1886 near the Reed Tunnel in Wardner. The treatment consisted simply of crushing ore to 2 in. and then to 1/2 in. through rolls in closed circuit with a bucket elevator and trommel screen. The undersize was further sized in trommels to 10 mm and 3 mm. Oversize from the latter was treated in Hartz jigs. The 3 mm undersize was classified in crude hydraulic classifiers furnishing sands to sand jigs, the overflow being dewatered in a long V tank which supplied sands to a Cornish buddle and to Frue vanners. The concentrates were of excellent grade, old records showing assays of 69 pct lead and 29 oz. of silver per ton. Tailings were high inasmuch as the provision for treating the slimes was inadequate. Since the erection of the first mill, the Bunker Hill plant has gone through many changes and improvements. In succeeding years, the flowsheet was enlarged somewhat with Huntington and Chilean mills, vanners, tables, ball mills, and flotation cells being progressively added. In the transition period to the present day practice, the object was not only to improve the equipment for better mechanical performance, but to add new equipment whenever practicable so as to improve both grade and recovery of the product at a lower cost. For the modern plant and flow-sheet, see Figs. 1 and 2. The history of flotation at Bunker Hill dates back to 1913 when experimental work was done in a cell in which the pulp was circulated through a centrifugal pump set outside the cell and discharged against a baffle in the cell. The cell was built with a spitzkasten, and the quiet zone in the latter tended to let the froth break down before it got to the overflow weir. To remedy this situation, a belt drag with light metal flights was arranged for drawing off the froth over a ramp in each cell. Recovery of lead was not as high as present day practice, but was so much better than the vanners that the cells were multiplied gradually to eight cell units. The mill men called them mud hens. Flow between the cells was controlled by a weir, which determined the pulp level in each cell. These early machines were called Bunker Hill machines. The tailings were later treated in pneumatic scavenger flotation machines in a series, producing concentrates for retreatment in the Bunker Hill cleaners as well as the final tailings. This system of flotation served with minor changes until the Fahrenwald machine was developed at Bunker Hill during the period from 1921 to 1925. In 1925, the Fahrenwald flotation machine gradually replaced the Bunker Hill machine, although the Hearing pneumatic scavengers for retreatment of the tailings from the Fahrenwald machines were retained in the lead section until 1928. The use of the Hearing pneumatic machine for cleaning the rougher concentrates was begun in 1924. In 1941, plans were made for remodeling and modernizing the concentrator, the goal being a modern concentrator employing the latest equipment and milling practices. The old wooden building was to be replaced by a steel and concrete structure. Shortly after preliminary work got under way, the United States entered World War II and the demands for metals increased. To meet this requirement, the management decided to increase the capacity of the concentrator to 1800 tpd. This was accomplished in record time by the construction and operation of a sink-float plant. Installation of this plant was the first step in the general plan for modernization. In 1947 the concentrator (including the sink-float plant) was enlarged to handle 3000 tpd. Milling operations today are at the rate of 2300 tpd, five days per week. During 1959, 453,000 tons of ore was beneficiated. The Bunker Hill concentrator is in three sections: the crushing plant, a 3000-ton capacity storage bin, and the concentrator building. The crushing plant is of wood design with a gunnite coating on the exterior.

Jan 1, 1961

By William J. Douglas

Critical path modeling (CPM) has been used widely as a tool to manage large-scale projects having many activities which are conducted in series or parallel. The construction industry is a regular user of critical path modeling as a planning tool. In this context, the method is used to provide an orderly schedule for all activities to forecast delays, slippages, and problem areas and to identify critical activities where resources should be directed. It also identifies others which have slack time, and provides information on the degrees of freedom and flexibility available in completing the project. The purpose of applying critical path modeling to an underground mining system is not primarily for scheduling, but as an analysis tool. In observing underground mining systems, it Is clear that repeated sequences of activities must take place for mining to proceed efficiently. Some of these activities must be sequential, while others be carried out in parallel. The fundamental difference between critical path modeling applied to mining versus a large-scale construction project are: (1) The activities in a mining system are cyclic in nature. (2) The location of the activity varies, and the entire process is not thought of as co-located, as is the case in a construction project. Another important aspect of the network development for mining systems is the degree of detail that is desired. One can be concerned with very macroscopic networks which represent, for example, an entire mine life cycle. Networks representing this problem would be more closely analogous to those of a large construction project. On the other hand, one might be interested in evaluating alternative ways of developing a property or of mining in a given section. More detailed networks representing the section activities are necessary to evaluate system parameters and their impact on long-term production.

Jan 1, 1978

By E. P. Youngman

The mining law of British North Borneo is entitled " The Mining Ordinance , 1927. 113 The only mining regulation or rule available is " Rules 313 , 114 passed in accordance with article 26 of the ordinance of 1927. Before the passage of this legislation , the country had no specific law governing the granting of mineral rights , although the land law contained provisions relating to mining lands . The land ordinance of 19135 still controls in a few details . All references in this paper , unless otherwise specifically designated , are to the mining ordinance .

Mar 1, 1933

By N. Thompson

The Right Hon. Viscount Long, late Secretary of State for the Colonies, in his inaugural address to the Empire Mining and Metallurgical Congress in London last June said: "I am more and more? convinced by every day experience that the development and strengthening of the Empire must depend upon individual effort and action, and that it is useless to look to Governments for assistance." I am inclined to agree with Viscount Long, to this extent, that the initiative must come from individual effort, but Government assistance is necessary to put the results of that effort and action into effect. It is perhaps fitting at a gathering of this kind to remind ourselves of the part the mining industry has played, not only in the development of the British Empire but in the world at large, in the promotion of modern civilization. We do know that all human progress has been coincident with the early discoveries in the recovery and treatment of metals and, as the centuries have passed, the human race has become more and more dependent on these sciences as factors of all progress, and no nation has ever become powerful and prosperous that has lacked adequate mineral supplies, or having these, has allowed them to be exploited by other nations.

Jan 1, 1925

By D. E. Cameron

"INTRODUCTION Grade control requirements for base and precious metal projects are an important input to both conceptual and feasibility mine plans. It’s the author’s experience that grade control input is insufficient at these critical stages. The few exceptions are a stimulus for this paper. A significant portion of CRC’s practice has involved assisting operations to solve grade control issues which were finally recognized as contributing to negative production variances. Even in operations perceived to be successful, deficiencies in grade control are often masked by measures taken by an operation to compensate a deficiency in one area with outperformance in another. The advantages in having a realistic and adequate grade control plan developed at an early project stage by a geologist(s) with considerable operations experience are manifold. It’s important for the geologist to prepare clear inputs into the mine plan backed by detailed supporting information in usable, flexible formats. When the decision is made to advance a project, the exploration team passes its model to a mine planner. The team doesn’t usually provide a detailed grade control plan with the block model, thus the planner tends to treat grade control as an activity to be rolled into a broader operating category. The consequences of highly compartmentalized mine planning can be severe in the long run. Once a plan is tabled, and especially once production begins, it is very difficult to improve grade control outside the fixed parameters of the operation. Major fixes tend to be costly in terms of time and dollars. Implementing needed changes to the grade control practices and culture in an established mine can present almost insurmountable difficulties. Hypothetical examples of grade control planning are presented to illustrate the author’s points. The diagrams are conceptual and schematic; any resemblance to actual deposits is coincidental. BEYOND 50¢/TON In more than a few cases, grade control cost is buried in a subcategory of mining cost with little more consideration than a plugged number. It is possible to do a word search in 43-101 Technical Reports on advanced projects and without finding reference to “ore control” or “grade control”. The idea is to reach the orebody by the shortest and least expensive means, achieving production and investor payback at the earliest possible occasion. This entails a low stripping ratio pit or a decline ramp with sills on ore to prepare the first stopes. The processes to achieve the target production, one of which is grade control, will fit into this framework. After all, there is a block model and the planner can see the grade and tons in each block. The exploration geologist whose responsibility was to bring a large percentage of the deposit into mineral resource owns the model and has released it to planning. Now comes the planning stage. Mine geologists haven’t been hired yet and they will be phased in with production. What could go wrong? Larger companies may have the geologists with operating depth who will be inserted into the mine planning discussions, but it’s not a given. Junior companies must often delegate the conceptual and detailed planning tasks to consultant groups. Is a senior-level grade control review part of the scope of work for the mine planning? If a good grade control plan is in place before the mine geology team is staffed, a key element of success is assured."

Jan 1, 2018