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By J. B. Hiskey

Introduction The domestic copper industry has suffered for some time from declining ore grades; rising costs associated with conventional mining, milling, smelting and refining; tightening environmental restrictions; and shrinking markets due to materials substitution. Ore grade depletion is a major problem. It is illustrated by the decline in average copper yield shown in Fig. 1. From 1979, copper grade has dropped 60%, lowering yields from 1.2% to 0.49% (Sousa, 1981). The US copper industry is taking drastic measures to enhance its competitive posture and to guarantee its future worldwide position. In a sense, this involves a general restructuring of the processing philosophy of US copper producers. Judging from recent trends, this restructuring relates to the application of solution mining techniques to the treatment of copper ores and low grade waste material. Recovering copper by leaching techniques has been practiced for centuries. As early as the mid-16th century, some Hungarian copper mines were recycling copper bearing leach solutions through waste heaps (Nash, 1912). In the US, recovering copper from dilute mine waters has been carried out for more than 100 years. There are, however, certain technical innovations that have elevated the importance of solution mining as a process for copper recovery. These include: • Advances in solvent extract-electrowinning (SX-EW); • Developments in acid and acid ferric cure processes for oxide and mixed oxide sulfide ores; • Improvements in heap and dump construction; and • Advances in in situ leaching technology. Generally, solution mining enjoys certain intrinsic advantages over conventional mining and milling. Compared to conventional milling, the combined capital and operating costs of leaching facilities are normally lower, start-up times are faster, and the leaching operation usually has less impact on the environment. Furthermore, solution mining represents an expedient way of extracting metals from small shallow deposits, and is particularly suited to the treatment of low grade sources. And, in the case of waste dump leaching, there is a tremendous resource in-place that has the mining cost already off the books. This paper updates current US copper solution mining trends. Solution mining systems Schlitt (1980) summarized the characteristics of the principle leach systems in the US. He pointed out that the wide variations in copper deposits make solution mining a more site-specific activity than conventional mining and milling. Heap leaching is usually selected for moderate to high grade ores having a copper mineralization that is amenable to acid leaching (oxides, silicates and certain sulfides). Higher grade ores mined specifically for heap leaching are usually treated to optimize copper extraction, therefore, crushing and some pretreatment (acid curing) may be justified. On the other hand, dump leaching practice usually involves leaching low grade waste rock placed on large dumps as dictated by topography and haulage costs. Mine waste is therefore treated in an uncrushed run-of-mine condition. Finally, in situ leaching is appropriate for either very deep ore bodies or for recovering copper from low grade rock left behind in abandoned pit walls, stopes, and subsidence zones from earlier mining activities. True in-situ solution mining should be defined as the leaching of ore in its original geologic setting. Heap leaching Heap leaching has a long history as a hydrometallurgical process for copper recovery. The methodology of heap leaching established at Rio Tinto in Spain more than 300 years ago is basically the same as that used today. Processing concepts, such as solution management (sprinklers and leach/rest cycles) and copper

Jan 11, 1986

By Mark E. Emerson

1967 will be remembered as the year the world realized it was running out of silver. In May of this year a new era in tin the history of the white metal was begun as the power of the U.S. Treasury to regulate world .silver markets was staggered by one of the most intense speculative flurries in recent times. In the past few months the price of silver has risen from $1, 29 to over $1.80 per troy ounce and with it have spiraled the prices of a host of silver-bearing consumer items. Legislation has, been enacted to conserve our coinage and meager silver stocks and today large quantities of non-existent silver are trading hands at a fast pace on the commodity exchanges throughout the world. Now that the price of silver has been set loose, forces are in motion to dull the world's appetite for silver. At the same time there is strong incentive to provide greater quantities of silver to satisfy the world's hunger' for the metal.

Jan 1, 1967

By A. Adu-Acheampong

The Mid-Tennessee Zinc (MTZ) mines, comprised of the Gordonsville, Elmwood, and Cumberland sites, last operated 4 years ago and are undergoing rehabilitation to begin production in 2008. The mines utilize a random room-and-pillar mining method that results in complex ventilation networks. Upon decommissioning, the mechanical ventilation units were removed and disposed of and several shafts sealed. In an effort to re-open the mines and operate in compliance with imminent Mine Safety Health and Administration (MSHA) diesel particulate matter (DPM) regulatory limits of 160TC µg/m3, a new ventilation system was required. The new ventilation system was developed primarily based on the diesel equipment required to meet production. Particular emphasis was placed on the DPM, diesel equipment utilization, main fan sizing, and fan locations to enable the mines to meet MSHA?s ventilation requirements in a cost efficient manner.

Jan 1, 2009

By Brad Hewitt, Jeff Belke

"Murrin Murrin Operations has not had a successful beginning. Numerous reliability and operability issues many of which are the result of design decisions have been addressed through mechanical and operational changes and the CCD circuit is no exception. Four design aspects of the CCD circuit that have caused and continue to cause operational problems are:1. the inclusion of solution neutralisation gypsum in the CCD circuit feed which was designed solely for HPAL residue without proper investigation of its impact on the achievable underflow density and resulting wash efficiency;2. the decision to construct the thickener base from thickened solids;3. the lack of redundancy in the overflow, underflow and tailings pipe work; and4. the lack of thickener operational flexibility in the central rake-lift and feedwell dilution system.In November 2002, the lack of operational flexibility in the rake-lift and the feedwell dilution system through mechanical modification as follows:•, CCD1 has a modified rake mechanism that now allows central vertical lift of 600 mm;•, CCD1 has forced dilution using the Outokumpu Turbodil® technology and replacing the E-Duc® technology of Eimco;The decision to install, the installation and the results of the CCD1 rake-lift mechanism and feedwell dilution system are discussed in this paper. The installation was justified on improved operational robustness and an increase in the in the underflow density of 1 per cent (per cent w/w). At approximately the same time process modifications in the solution neutralisation circuit were implemented and these changes altered the rheology of the slurry reporting to CCD1. Since the modifications to CCD1 and the solution neutralisation circuit, the CCD circuit has averaged a 2 per cent improvement in the circuit underflow density.The CCD1 modification was completed on time and mechanically has performed well. From a risk point of view, the central rake-lift and Turbodil®dilution system add a degree of freedom and robustness to CCD1 operation that has extended the range of operational confidence. In this respect, the modification has been a success and is complementary solution neutralisation improvements."

Jan 1, 2005

By M. A. Barakat

"Adsorption of heavy metal ions specifically, Cu(II), Zn(II), Mn(II), and Cr(VI) from aqueous solution on synthetic 4A Zeolite was evaluated. The 4A zeolite was synthesized previously by dehydroxylation of low grade Kalabsha Kaolin at 800 °C, and reacted hydrothermally with 2-4 M NaOH solution at 100 °C for 2h. The adsorption capacity of the metal ions were found to be strongly dependent on pH and initial metal ion concentration. At the optimium conditions the adsorption capacity decreased in the order Cu(II) > Zn(II) > Mn(II) > Cr(VI) ions. Almost complete adsorption was achieved for both of Cu(II) and Zn(II) ions at pH > 6, while the adsorption capacity for both Mn(II) and Cr(VI) was 96, and 55.3 % at pH 11 and pH 3, respectively. The results also showed that the grain size of the 4A zeolite has a little effect on the adsorption capacity. The experimental data was compared with two adsorption isotherms, Langmuir and Freundlich isotheroms. The results showed a good agreement of the Langmuir plots with the experimental data.1. IntroductionSeveral industrial wastewater streams may contain heavy metals such as Cr, Cu, Pb, Zn, Co, Ni, Mn, etc. including the waste liquids generated by metal finishing or the mineral processing industries. Heavy metals are considered hazardous pollutants due to their toxicity, even at low concentration, and nonbiodegradability. Increasing level of heavy metals in natural water bodies poses a serious threat to all living species including humans. It is, therefore, essential to reduce the heavy metal concentration in effluents/wastewater before it is discharged into the water bodies [1]."

Jan 1, 2008

By J. M. Dempsey, R. A. Litle

Asarco Incorporated’s Omaha, Nebraska refinery site and the City of Omaha’s downtown redevelopment projects are the perfect example of the marriage of the Brownfield and Sustainable Development strategies. Nebraska’s largest voluntary site remediation project created a focus point for redevelopment and has spurred over $1 billion in economic investment within a 1-mile radius of the site. Asarco was faced with options of very expensive and uncertain facility upgrades or a shutdown. Local leaders, Asarco, and regulators worked together to convert a controversial and complex site to a park-like redevelopment area with numerous long-term benefits to the City and the environment.

Jan 1, 2004

By K. Lang

A case study is provided that highlights the successful use of high efficiency electrical submersible pumps (ESPs) adapted from the oil and gas industry for a large scale, open pit mine dewatering operation. In this case, the mine is Goldcorp?s Peñasquito Mine, Peñasco and Chile Colorado open pit development areas in Zacatecas, Mexico. At the time of publication (July 2012), there were 18 vertical bedrock dewatering wells producing an average flow rate of 350 liters per second (lps) from the Peñasco and Chile Colorado development areas. Average pumping rate per well was 18 lps, with a maximum of 44 lps. The depth of wells varies from 330 m to 500m, and includes both in-pit and perimeter (ex-pit) pumping centers. A network of 50 piezometers was used to monitor the response of groundwater levels to pumping. Since dewatering operations were initiated in 2007, groundwater elevations decreased overall, from approximately 1950 m above sea level (masl) to around 1625 masl, for a total of 340 m of drawdown. The pit floor elevation was approximately 1655 masl. All of the producing wells were constructed with 16-inch boreholes, completed with 10-inch diameter blank casing and louvered screen sections and equipped with ESPs. The application of ESPs has proven to be highly effective in the case of Peñasquito?s dewatering operations. Noted advantages include the following: ? Small diameter pump allows use of smaller diameter boreholes (16 inches) and casing / screens (10 inches) reducing well drilling and construction costs ? Greater application range for flow rate and total dynamic head ? Variable speed drive systems for greater energy efficiency and flow rate optimization ? Integration of downhole instrumentation into the motor and pump assembly The advantages and benefits of using high efficiency ESPs revolutionized the dewatering program at Peñasquito open pit mine as evidenced by the number of deep vertical well installations and high dewatering flow rates and total dynamic head requirements.

Feb 27, 2013

This briefing was sponsored by the Bureau of Mines to summarize ongoing and recently completed chromium-chromite research and resource assessment activities by the Bureau. Through the series of 18 presentations compiled herein, Bureau personnel covered a wide range of topics including U.S. chromite and chromium trends and usage patterns; foreign and domestic resources; and research activities on mineral characterization and beneficiation, chemical and pryometallurgical processing of chromite and chromium-bearing wastes, new low-chromium alloy and coating substitutes, corrosion- and oxidation-resistant stainless steels, and chromium-containing refractories.

Jan 1, 1986

This summary of State laws on explosives was compiled primarily to ascertain what subjects relating to their control have been acted upon by each State legislature and, in general, how they have been treated. It does not include any legislation passed after 1942, or any proclamations, regulations, or administrative orders. It does not purport or attempt to be authoritative. If any problem arises involving interpretation of the statutes of any particular State, the original source must be consulted for the exact words used by the legislature. This summary, however, will be useful in determining whether relevant statutes exist and in locating them quickly, with a minimum of effort. It will be of value also in comparing statutes in one State with similar statutes in other States to determine what construction has been placed upon them by the courts of those jurisdictions or to contrast the varying provisions of many States upon a single subject. To make these comparisons easier, the statutory provisions for each State have been grouped under several major topics in outline form. Although

Jan 1, 1943

By D. Harrington

The record of fatalities from mine explosions in the United States during the past 3 years has been the best in the history of the mining industry. During these 3 fiscal years, mine explosions have resulted in an average of 4I0 deaths per year, as compared with an average of 153 deaths per year for the preceding; 5 years; an average of 542 deaths per year for the 3-year period 1907-09, inclusive, just before the organization of the U. S. Bureau of Mines; and a yearly average of 265 deaths per year for the 20-year period prior to 1929. This remarkable reduction in deaths from mine explosions demonstrates clearly that mine explosions can be controlled; in fact, they can be prevented when or if the mining people of the United States see fit to take the readily available precautions necessary to bring about this desirable objective. Several large coal-producing States, which in the past have had numerous disastrous explosions, have been free from such disasters for continuous periods of as much as 6 years or even longer. The bituminous mines of Pennsylvania, the largest coal-producing State, give a good example of what can be done to prevent explosions; this State has had only one major explosion (and it resulted in 7 fatalities) during the past 6 years, and no explosion occurred in the several hundred bituminous-coal mines of the State during the past fiscal year. This is a truly remarkable record when compared with past performance in any year in the operation of coal mines in Pennsylvania.

Jan 1, 1936

By C. P. Haller, S. J. Aresco

"INTRODUCTION The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heat¬ing value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the fusing temperature of ash and the free-swelling index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions./ issued by the Bureau; the samples are analyzed in the Bureau's laboratory to determine whether the coal is of the quality guaranteed by the contractor and, if it is not, a price adjustment is made.Analyses of the delivered coal and ""tipple"" samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. Moreover, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.The Government purchased approximately 5-1/2 million tons of coal in fiscal year 1951. In connection with these purchases, the Bureau analyzed 10,700 samples. These are published for the use of Government officials and the public. A series of publications s been completed on coal analyses by States, or, where production is small in any State, by groups of adjacent States. In addition to analytical data showing composition and quality of coals of the States, the publications contain brief descriptions of the geological structure of the coal basins, typical mining conditions in the various districts, the principal economic data of the industry, and the relationship of mine or channel samples to delivered and tipple samples. The present publication covers many States but deals only with the analytical data of the coals.The technical papers published by States, with their numbers are: Alabama, 347; Alaska, 682; Arizona, California, Idaho, Nevada, and Oregon, 696; Arkansas, 416; Colorado, 574; Illinois, 641; Indiana, 417; Iowa, 269 and 706; Kansas, 455; Kentucky, 308 and 652; Maryland, 465; Michigan, North Dakota, South Dakota, and Texas, 700; Missouri, 366; Montana, 529; New Mexico, 569; Ohio, 344 (and Bulletin 499); Oklahoma, 411; Pennsylvania Bituminous, 590 (Supplement, 645); Pennsylvania Anthracitic, 659; Tennessee, 356 and 671; Utah, 345; Virginia, 365 and 656; Washington, 491 (Supple¬ment, 618); West Virginia, 405 and 626; and Wyoming, 484."

Feb 1, 1953

By Ulf G. Gwildis

The Bright water Conveyance System includes 21 km of tunnels mined by two earth pressure balance Tunnel Boring Machines (TBMs) and two slurry TBMs. The probabilistic baseline approach defined in the Geotechnical Baseline Report (GBR) can representatively be verified by use of a comprehensive tracking system to identify face conditions that allows comparison with the baselines. The glacial geology includes a high lateral variation in soil types that, when combined with the pressurized face tunneling methods, creates challenges for documenting face conditions. Baseline tracking using spoil samples and TBM operational parameters provides information to document actual conditions and support resolution of differing site condition claims.

By M. Didyk

The final objective of a mine ventilation project is to find a way of supplying the working faces with the necessary quantity of air to dilute all the possible air contaminants to safe limits and to maintain the temperature, humidity and oxygen content within desirable limits. To accomplish the aforesaid, decisions have to be made at early stages of planning and design of a mining operation. That is, ventilation and mine planning are closely related and interdependent, and experience has proved that improvisation as related to mine environment is rarely optimal in ventilation engineering. Mine management should be concerned with two general aspects of ventilation problems. The first is related to the statuatory requirements which are usually the minimum standards that have to be maintained. During the last two decades, mining laws have become increasingly stringent and management of operating mines had to face the effects of these externalities. In some cases these required either a production rate reduction or additional mine development. The second aspect that management should not overlook is the technical and economical importance of mine ventilation on the overall mining cost. In coal mining it is necessary to move, on an average, five tons of air through the mine for each ton of coal produced. The power cost incurred is perhaps the single most important direct cost assigned to ventilation but it is not the only one. Other costs that should be considered include the supervisory labor cost, fan depreciation and maintenance, doors, stoppings and regulators construction cost and maintenance, the additional mine airways development and maintenance because of ventilation requirements. That is,

Jan 1, 1977

By Michael Kukay, Paul Conrad, Cosmas Opoku-Ware

This project is exploring the potential for developing trees tolerable to degraded un-reclaimed mine site soils and tailings as a solution to re-establishing long-term tree growth on those sites. The project incorporates growing tree seedlings in an underground greenhouse grown from seeds planted in the degraded mine soils in which they will eventually be planted. The outcome of the project is expected to lead to a successful solution for re-establishing tree growth in soils and tailings containing high metal concentrations with minimal post-planting human intervention. The research is being conducted in an underground greenhouse located 100 ft below the surface in the old Orphan Boy Mine Underground Mine Education Center (UMEC) located on Montana Tech’s campus in Butte, Montana.

By Ali Ameli

Design loads are limited for piles relying upon toe stresses in rock due to uncertainty about the rock quality over the whole pile diameter because of rock mass properties or construction effects. The paper discusses the use of video images to evaluate rock quality at the bottom of piles socketed into graniodorite bedrock in a steel pipe pile project. Skillful interpretation was required to assess the 3D properties of the rock from video images. It is necessary to observe the rock mass characteristics near the project site for better perception of the rock features from the images. Video image interpretation skills were established by the evaluation of the cores drilled under the socket base and the results of pile loading tests. Correlations were found between rock appearance in the images and the rock socket drilling records. Rock socket acceptance criteria were developed through monitoring the drilling operations for the specific site procedures. Video images then served as one of the quality-assurance tools together with probing and pile loading test. Lessons and methods learned from video inspection in this project could be used to evaluate rock quality in similar cases.

Jan 1, 2006

By J. O. Osterberg

The realities of foundation enginering are that the work never proceeds exactly as expected. The various reasons, exploration, design, construction, and legal are discussed. Case histories are presented with an analysis of why the projects did not turn out as expected and how the difficulties might have been avoided.

Jan 1, 2010

FREQUENTLY the Survey Department is caIled upon to estimate the quantity of material in various dumps, dams piles, etc... and in the carrying out of this work various methods may be employed.The method used will vary according to the particular case in hand, and factors such as accessibility of the top of the dump, steepness of its sides, height, and the condition of the material to be estimated. A certain amount of "give and take" must be adopted in the treatment of small local cavities and mounds.In all cases it is desirable that the surveys made should be tied on to the lease surveys for the purpose of location, and that all levels should be reduced to the mine datum. It is also desirable to obtain levels of the original surface before deposition of the material to be estimated. If these have not been obtained beforehand, levels and transfers round the top will be the next best. If space is availabIe, flat surface is chosen as a site for the dump, etc. This is of the utmost importance in those cases where the material will have to be...

Jan 1, 1925

By J. P. Welsh

Ground Modification construction is rapidly evolving in the United States. An assessment of the construction status of Ground Modification methods with their dates of introduction and general acceptance in the United States is summarized. Seven of these techniques are discussed in depth with short case histories; namely, Dynamic Deep Compaction, vibro-compaction, vibro-Replacement, chemical grouting, compaction grouting, slurry grouting and jet grouting. Additional case histories are presented to illustrate the trend of combining Ground Modification techniques to solve specific site problems.

Jan 1, 2010

By WILLIAM F. McMURRAY, James O. Lewis

The Bureau of Mines is investigating the technology of petroleum and its products, the investigation including well-drilling methods and the transportation, treatment, and utilization of petroleum and of natural gas, with especial reference to the prevention of waste and to increased efficiencyin the development of oil and gas resources in land belonging to or controlled by the Government. During. the winter of 1912-13 the enormous waste of the gas encountered while drilling for oil in the Cushing field, Oklahoma, called forth protests from various sources, and appeal was made to the President of the United States and to the Secretary of the Interior in behalf of the landowner and of the public in general. The facts were wanted regarding the amount of waste and the technical conditions that were responsible for practices causing it. An investigation was ordered and conducted under the direct supervision of the late J. A. Holmes, the first Director of the Bureau of Mines. R. S.Blatchley was sent to investigate the amount of waste going on in the Mid-Continent flelds.s In the latter part of March, 1913, J. A. Pollard and A. G. Heggem were sent to Oklahoma to study well-drilling methods with reference to the waste of gas from wells on Indian lands and to suggest means of preventing the waste of natural gas on such lands. Pollard and Heggem decided that the mud-laden fluid process, which had been used successfully for some years in Texas, Louisiana, and California was the method that would meet the situation most efficiently and economically. The method was accordingly demonstrated in Oklahoma. In 1914 Congress provided for the employment of six oil and gas inspectors to supervise oil and gas mining operations on lands of the Five Civilized Tribes in Oklahoma and to conduct investigations with a view to the prevention of waste. Positions under this appropriation have been held by William F. McMurray, James O. Lewis, Harry D. Aggers, Ralph R. "Weed,George W. McPherson, James C. Fowler, Louis W. Courtney, and Carl H. Beal, the technical work of these men being directed "byW. A. Williams, chief of the petroleum division, Bureau of Mines. After careful and impartial investigation of conditions in Oklahoma, these men also decided that the mud-laden fluid process was the one best adapted to prevent further wastes. In 1915 laws were passed by the State of Oklahoma that provide for the conservation of natural gas and oil, authority being given to the corporation commission to make rules and regulations and to employ agents to enforce them. After hearings and investigations, the corporation commission reached substantially the same conclusions as the Federal agents regarding the importance of the wastes and the best methods of conserving the gas. Technical Papers 66a and 68b were published by the Bureau of Mines in December, 1913, and January, 1914, respectively. Technical Paper 66 deals with the mud-laden fluid process in general and No. 68 with its application in Oklahoma. The interest aroused by these publications has been so widespread that within two years the first editions have been practically exhausted. Rather than reprint these publications, it has been considered advisable to replace them with the present report, which includes the results of more recent investigations. The methods of using the mud-laden fluid are an outgrowth of the rotary drilling system, which was developed in Texas and later employed in Louisiana and California. Some of the principles of the use of mud fluid had been observed and used to a limited extent for a long time in cable-tool drilling. So far as known it was first used successfully with a circulator and cable tools in the Coalinga field, California, in 1906,Harry D. Aggers, one of the contributors to this paper, working on the well. The part of the Bureau of Mines has been to call attention to its merits and to demonstrate its practical use in fields like those of the Mid-Continent.

Jan 1, 1916

By R. S. Dean

[Methods s of preparing the manganese metal that has been used in chemical and metallurgical investigations have passed through a cycle. Most of the investigations made before the turn of the century, used Moissen's pyrophoric manganese.3/ This material was made by electrolysis into a mercury cathode and distillation in vacuo. The material was essentially pure, and investigations in which it was employed (with proper precautions against oxidation) led to accurate results on tie intrinsic behavior of metallic manganese.]

Jan 1, 1941