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By Jerry F. Parola

In current practice, pile foundation design is based on a general under-standing of pile-soil interaction during installation and superstructure-pile-soil interaction after construction. The pile design is a reflection of experience, precedent and judgment for normal piling practice of working load capacities up to approximately 100 tons with corresponding ultimate capacities up to 200 tons. For higher capacity piles, pile design is even less predictable. In particular, the feasibility of pile installation is an important design consideration that must be given the proper attention. An installation capability that is not given the required emphasis can cause unnecessary problems.

Jan 1, 1986

By R. Blickensderfer

Maintaining an adequate supply of minerals and metals to meet national economic and strategic needs is the overall goal of the Bureau of Mines, U.S. Department of the Interior. One method of achieving this goal is to conserve scarce metals by cladding a plentiful base metal, such as iron, with a scarcer metal. To investigate cladding, a vacuum-rolling mill capable of rolling bimetal specimens at temperatures to 1,300° C in a residual gas pressure of 2 x 10-5 torr was established. Metals that were successfully bonded to iron included stainless steels, chromium, nickel, nickel alloys, copper, and several refractory metals including molybdenum and titanium. The effects of the rolling temperature, reduction in thickness, rolling speed, and residual air pressure on bonding strength and bend ductility of the bimetals were determined. Optimum rolling conditions produced bimetals with bond shear strength essentially equal to that of the iron base metal.

Jan 1, 1980

Kaiser Aluminum & Chemical Corp. announced that it planned to spend $66 million to increase the efficiency of its Baton Rouge, Louisiana, alumina plant. The improvements are designed to reduce energy consumption but will not change the annual capacity of the plant, now rated at about one million short tons. The project was expected to be initiated immediately and be completed by 1982. ALUMINUM Producers in this country posted unalloyed 99.5 percent aluminum ingot at 53-57.5 cents per pound, yet actual selling prices were closer to 53 cents. Domestic merchants quoted unalloyed ingot on a spot basis at 54-56.3 cents. London Metal Exchange 3-month forward contracts fell during November's trading from 55,2 cents to 52.8 cents per pound.

Jan 1, 1978

By D. Caiden, C. S. Covil, P. J. Chamley

The paper describes the background to alternative delivery models, drawing on international experience, and introduces Project Alliancing/Contract Partnering, common risks and risk sharing on tunnel projects. A plea for early contractor involvement in design is made before describing some whole life design implications for tunnels. The paper concludes with four short case studies; Channel Tunnel Rail Link in the UK, Hull Waste Water Tunnel in the UK; Island West Sewage Transfer Station in Hong Kong, and the New Southern Railway in Australia.

Jan 1, 2005

By N. C. Saxena, S. K. Puri, A. K. Pal

The condition-based monitoring system is an important innovation for reducing the downtime of costly, heavy earth- moving machinery (HEMM). Vibration severity measurements were made on the HEMM located at the Gevra Project, the largest coal opencast project in India. Whenever the vibration severity levels exceeded the permissible limits, necessary actions were taken to replace the defective parts of the ma- chine. The systematic vibration monitoring of 120-t (132-st) dumpers, followed by corrective measures led to a substantial increase in component life (8.18% for an 445E Dressor and 28.44% for an MK-30 Unit Rig). The associated costs (including spareparts) were reduced by 21.55% and 25.74%, respectively. Because of the reduced downtime, savings for these two dumpers over the period from March 26 to June 25,1998, were of the order of Rs.26.47 (US$0.649) million.

Jan 1, 2000

By M. C. Malamphy

A general description of the activities and results of bauxite investigation by the Bureau of Mines at its bauxite project in Saline and Pulaski Counties, Ark., has been given in Report of Investigations 4251. The factual data obtained during the project are reported in a series of Reports of Investigation beginning with No. 4251, of which this is the ninth. The data are accompanied by maps showing the location of holes drilled and the deposits developed. Each area upon which work was done is reported by half townships. Each bauxite deposit investigated was assigned a name and a number for ready reference and identification, and its location and name are shown on the appropriate half-township map. The description of each half township is followed by a description of each deposit developed in that half township map. The 14 half-township maps and 77 detail maps of the bauxite deposits in this series of reports give the locations and numbers of all the holes drilled on the project except the deep holes drilled to test the geophysical anomalies. The locations of those holes show on figure 13 in volume 1. The descriptions of the deposits developed are followed by complete detailed logs of the drill holes. Many of the widely spaced exploratory holes did not discover bauxite of minable thickness and grade. The pertinent information obtained from the widely spaced exploratory drill holes has been summarized and tabulated, and a table for each half township is given with the discussion covering that area.

Jan 1, 1948

By Larry H. Heflin

The Washington Metropolitan Area Transit Authority's Wheaton Station and tunnel design was completed and offered for bid in the Spring of 1983. The format was unique to the Authority: a four part, four fiscal year contract developed in response to funding limitations with construction divided into four stages allowing the maximum amount of work to be done each year for the funds available. The bid was based on the entire contract, but was orginally awarded for only the first year's work. Each year's work had a maximum funding limitation thus safe guarding the Authority from a grossly unbalanced bid. The Authority's estimate for this work was $83,871,524. The low bid came in at 61% of this for a total low bid of $51,512,058. The low bidder was ILBAU America Corporation whose home offices are in Austria. Following receipt of the bids (and resolution of objections cited by other bidders who felt that the job could not be done for the $51 Million dollar figure), a Notice-To-Proceed was given on October 5, 1983. The construction contract allows a Value Engineering Change Proposal, called a VECP which is initiated and developed by the contractor to change the drawings, specifications or other requirements of the contract. Among other things the VECP should decrease the contract price while maintaining the service life, reliability, ease of maintenance, and standardized features and appearance and not require an unacceptable extension of the contract time. A VECP must estimate the amount of the net savings

Jan 1, 1985

By Dave Bulled, Khiratt Husain

"The use of High Pressure Grinding Rolls is gaining significant interest as a replacement for SAG milling in the comminution of hard rock ores because of the potential for reduced costs in terms of energy and grinding ball consumption. Estimation of expected energy consumption for fullscale operations has conventionally involved the testing of a few fairly large samples in pilot scale HPGRs. This paper describes the development of a small-scale batch test method for determining a work index for HPGR of a large number of samples that can be used to show the variability of the ore as an integral part of a geometallurgical approach to circuit design and production forecasting.The test equipment that was developed comprises a hydraulic press with adjustable pressure operating on small batches of ore in a locked cycle test procedure. A work index measurement was determined that links the specific energy consumed in the test to the breakage achieved such that the index can be used to predict comminution energy requirements.The measurements were calibrated against laboratory scale HPGR equipment to develop a model for design and forecasting that includes crushers, HPGRs and ball mills in a complete comminution circuit.INTRODUCTIONEstimation of the expected energy consumption for full-scale HPGR operations has conventionally involved the testing of a few fairly large samples in laboratory and pilot scale machines (Danilkewich, 2006). With the financial input of five mining corporations, SGS Lakefield Research has developed a small scale test capable of providing relevant information on the variability of energy consumption and size reduction from drill core samples. It is our intention that the values measured in the test will be scaled up, through benchmark comparison with pilot sized and full sized HPGR units, to allow plant design and throughput forecast on a block by block basis of the mine plan using a new CEET program. CEET® (an acronym for Comminution Economic Evaluation Tool) is an advanced grinding design and performance predicting tool that uses energy relationships to model the performance of SAG / Ball mill circuits."

Jan 1, 2008

By Oswaldo Ortiz Sánchez

El presente trabajo describe la alternativa de uso del mortero de resina en la fijación de pernos de anclaje de las excavaciones mineras, consolidación y disipación de vibraciones en los cimientos de plataformas para la instalación de molinos, winches, tolvas, etc. Esta opción surge en respuesta al problema de reforzamiento con pernos de anclaje en ambientes con aguas corrosivas o en proceso de deformación acelerada en las excavaciones mineras, así como ante obstáculos de subsidencia de cimentación en plataformas, donde se encuentran instalados equipos de gran tonelaje, y que producen fuertes vibraciones durante su funcionamiento.

Jul 31, 2003

By Gary L. Stecklein

This final report delineates the findings of the test programs, simulations, and analyses performed to determine the requirements for the effective application of berms and guardrails as truck restraint systems for elevated mine roadways. Included arts criterion for effective vehicle restraint for guardrail applications and recommendations for berm applications based on scale model tests and computer simulations. Full scale haulage vehicle-berm interaction field tests were performed to correlate the results of these model tests and computer simulations. Recommendations for the construction of berms were made on the basis of tests of berm bearing strength, response of the vehicle to different berms, and predictions based on the obtained correlation

Jan 1, 1981

By Joachim Klein, Frank Reimann

Nodular-graphite cast iron (GGG) is a material similar to steel, and one which exhibits excellent properties, in particular for components exposed to pressure. GGG cast iron has been used in many cases when sinking mine shafts with conventional tubbing. With linings made of cast iron tubbings (the backfill concrete is not integrated into the calculations, and merely serves as bedding) the properties of the cast iron can be made full use of, provided the tubbing is made to the appropriate cross-section. Calculations have shown that better static values can be arrived at when using cross-sections other than those of tubbings made to conventional German standard. The cross-sectional design of the new types of shaft lining made from GGG is to be developed on these lines irrespective of the cast iron structure being only stressed component or its restistance function being combined with the one of concrete. GGG 50 is used for the first time to make the reinforcing inner liner of a main shaft currently sunk in Germany. The physical properties of nodular-graphite cast iron, strength and deformability, suggest that, in the future, its application will not be restricted to shaft support but also in tunneling. New moulding techniques with better three-dimensional modelling resulted in new tubbing designs as installed e.g. for the Hannover underground at present. Shield-driven tunnels have to withstand earth and water pressure, apart from axial machine loads. In this field time is money as well. Therefore easy handling and quick installation are necessary for successful, use. Last but not least, safety is of first-order importance for work in shaft sinking and tunneling. Cast iron lining systems, accordingly, are adequate systems, in particular for excavations underneath water for transport systems and for goods and passengers.

Jan 1, 1987

By Elisa Alonso

Recycling is generally a more sustainable alternative to landfilling. Its financial costs however, do not always justify its practice, especially in the short term. As a result, even for precious metals such as platinum, significant amounts can end up unrecovered. In considering risks of materials scarcity for firms that require platinum and platinum products, this paper examines how recycling provides additional benefits as a risk-mitigating strategy against scarcity. The experimental platform for this examination is a System Dynamics simulation model that strives to capture the dynamics of platinum market supply, demand and price. The detailed structures of supply and demand are key features of the model. Results show that since the secondary supply of platinum depends on a supply chain separate from primary extraction, recycling can diversify the risks of primary supply instabilities and reduce the impact of price fluctuations upon firms.

Jan 1, 2009

By Y. P. Chugh

This is the final report of a study done by IIT Research Institute for the Bureau of Mines to identify the problem areas and technological inadequacies in noncoal (metal, nonmetal, stone, and sand and gravel) mining and processing systems that are the primary causes of death, injury and occupational disease, and to make recommendations to improve safety and health in these operations. The findings and recommendations presented in the report are based on: (1) analyses of MESA injury and employment data for the period 1961-70, MESA fatality reports for underground noncoal mines (1968-72) and lost time accident data for 1970-72 obtained from mining and processing operation: (2) visits to a variety of noncoa1 mines and mills throughout the country to observe the operations and to study the safety organization and practices used in the industry and (3) interviews with industry and government representatives knowledgeable in the field of noncoa1 mining and processing safety and health. The report provides a comprehensive overview of safety and health problems.

Jan 1, 1974

By Gaby Steinbach

A novel synthesis is described for the preparation of supported gold catalysts for low-temperature CO oxidation. The novel route is a variation of the inverse co-precipitation method and requires amphoteric metal hydroxides, with zinc and aluminium hydroxides chosen. Catalysts were prepared by inverse co-precipitation (ICPa) and by the novel route (ICPb) and tested for CO oxidation at 60ºC. Preliminary results showed the novel route to be superior to ICPa; the catalysts prepared by ICPb showed higher catalytic activities. The effect on catalytic activity of parameters such as pH, calcination temperature, washing of precursor and calcined catalysts and ageing was investigated. A preparation pH of 9 and a Zn to Al mass ratio of 3 proved to be optimal. It was possible to remove residual chloride by washing thereby enhancing catalyst performance. Ageing and Mg citrate addition were also shown to improve catalyst performance. Characterization of the catalysts revealed that better activities were obtained when the support was more crystalline and had a higher surface area. The presence of carbonate-containing species in the support decreased catalytic activity. 197Au Mössbauer Spectroscopy revealed the presence of Au3+ when catalysts were heat-treated at temperatures of 200ºC and below. Catalysts calcined at 400º had 75% of the gold present as Au0, with the remaining gold present as Au3+.

Oct 1, 2003

The Pogo Mine, near Delta Junction, Alaska is a 2500 TPD gold operation employing processes including grinding, gravity, rougher flotation, leach, CIP, and E/W. An OCS(Optimizing Control System) expert control system has been implemented on rougher flotation in early 2008. The OCS system communicates with the Plant DCS(Distributed Control System) through OPC(OLE for Process Control) communication. The initial strategy was to control the flotation cell froth level set points to achieve target froth velocities. This strategy was enhanced by controlling both level and air flow setpoints. The flotation cell air and level are adjusted to reach cell pulling rates (froth velocities). The pulling rate setpoints for each cell are determined based on downstream capacity (concentrate surge tank level). The effect of pH and upstream disturbances is also taken into account in adjusting the air and level setpoints. Feed forward compensation is employed down the flotation row to minimize disturbances.

Jan 1, 2009

By D. Jacobson

There are many different machine setup parameters and variables that affect the production of cone crushers in a mineral processing plant. One of these variables is the eccentric speed at which the cone gyrates. In June 2012, pilot tests were conducted on a 200 hp high speed cone crusher to determine the production and operating conditions over a wide spectrum of eccentric speed. Every plant will have variations in the ore characteristics and feed rates throughout the life of the mine, and at times throughout a single shift of operation, which result in non-optimal use of the crushing energy and inconsistent process control. For high speed cone crushers, the crusher will exhibit a different capacity, power required, and discharge size distribution as the speed ranges over the design limits of the machine. This study documents the measured variation in production and energy efficiency both when the crusher was ran at full capacity as well as when the feed to the crusher was not sufficient to run at full capacity. Overall, the results match theory and the capacity and power fluctuated by 25% and 17%, respectively, over the speed range when operated full while there was an overall trend of slightly coarser discharge size distribution as the speed decreased. The results with the fixed feed rate were more telling, as the crushers had 4-14% higher production when making a theoretical minus 12.5 mm product when operating at the optimal speed as compared to the worst speed in the ?typical? speed range for this application. Secondary analysis of the fixed tonnage testing also showed that the power draw was more consistent with lower magnitude spikes at the higher speeds (higher cavity level), as on average the standard deviation of the power draw increased from 7% to 18% and the peak power spikes from 20% to 48% over the speed range tested. The findings lay groundwork for more efficient plant design. Varying the speed of the crusher can be used to tune the crusher speed during commissioning, adapt to changing ore conditions over long periods of time, or be used as a dynamic input into an advanced control system. Each action above would serve to make the crusher(s) more productive and more energy efficient, and would also have mechanical benefits for the machine. Key Words: cone crusher, ore reduction, process control, crushing efficiency

Feb 27, 2013

By Dhananjaya Senapati, E. V. S. Uma Maheswar, C. R. Ray

Carbothermic process of Ferro Silicon production is primarily a slag-less process. However, slag formation is observed in the regular operation as experienced by almost all the Ferro Silicon Producers in different pro-portions. The problem of slagging in the furnaces may be due to: a)Variation in the input burden charge material quality b)Fluctuations in the Carbon balance and/or c)Fluctuations in the Electrode penetrations The problem will be more severe in nature with the increase of the size of the furnace. The operation performance of the furnace gets badly affected if the slag formed in the furnace is not removed from the bath in time and to the maximum extent possible. It is, therefore, very essential to know the characteristics of the slag formed in the Ferro Silicon Furnaces, besides eliminating the very cause of formation itself; and to find the routes of draining of the same from the furnace bath effectively. This paper envisages the effects of using the LIME STONE in the Ferro Silicon Burden in stabilizing the 48MVA Furnace for improved performance and better consistency. Quality fluctuations in the available Raw Materials are compared with that of the requirements for the Ferro Silicon production. The furnace operational data is compared for 12 months period each for the period corresponding to the before and after usage of lime stone in the burden and found encouraging results in the performance. Implications of use of Lime Stone in the burden on the quality of the output alloy are also studied.

Jan 1, 2007

The Bureau of Mines found sulfur hexafluoride (SF6), released from a lecture bottle, to be an ideal gaseous tracer for studying mine ventilation systems. Air samples were collected in glass syringes and analyzed by electron-capture gas chromatography. In these studies, the lower limit of detection was about I part per billion by volume (ppb) of SF6 per part of air. Experiments conducted in a Pennsylvania limestone mine showed this technique useful in evaluating the effectiveness of auxiliary fans, measuring low flow velocities, probing the air circulating near a working face region where ventilation appeared to be poor, and estimating volumetric flow rates in airways of large cross-sectional area and having low flow velocities. This technique was also used in a western vein-type metal mine to measure the amount of return air being recirculated into the intake air due to leakage through old stoped areas.

Jan 1, 1974

By E. Robles

The Tati Activox® Project (TA®P) is the first step towards the implementation of the Norilsk Nickel Activox® process. The ultrafine grinding (UFG) and autoclave pressure leach process conditions are the heart of the Activox® patent. Low grade base metal sulphide concentrates are leached in the process to recover the base metals and to produce LME grade nickel and copper cathodes and cobalt carbonates. The downstream processing of the metal-containing liquor produced by this process includes solvent extraction circuits to extract and concentrate metal-rich solutions, before the various final products are obtained. This paper gives an overview of many of the relevant design aspects taken into consideration in the design of the Tati Activox® solvent extraction circuits. It addresses key design elements related to leach process conditions such as scaling, materials selection for corrosive solutions, pH control, crud formation and treatment, multiple SX trains designed to prevent organic cross-contamination, and design aspects related to the mitigation of fire risks.

Jan 1, 2009

By J. B. Elizondo

This paper, which describes mining methods and practices at the Piokee mining unit and the Piokee expertmental mining project of The Eagle-Picher Co. in northeast Oklahoma, is one of a series being prepared by the Federal Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. The Piokee unit, comprising the Piokee, Rowe, Lucky Syndicate, and parts of the Netta White and Otis White leases, is in the SW1/4, W1/2NW1/4SE1/4, and W1/2SW1/4SE1/4 sec. 17, T. 29 N., R. 23 E., Ottawa County, Okla. (figs. 1 and 2), The 200-acre tract is adjacent to the town of Picher and near the heart of the Picher field of the Tri-State zinc-lead mining district.

Jan 1, 1959