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By J. P. BONARDI, C. W. Davis, R. B. Moore, J. W. MARDEN, S. C. Lind, J. E. Conley

The rare metals are becoming increasingly important to our industries. Rare-metal alloys have properties which indicate that we are only on the threshold of the possibilities of their utilization, not only in making nonferrous alloys, but also as special steels. Not only are their uses broadening rapidly, but the metals are affecting our industries in other ways. The oxides and some salts are used as pigments; others have medicinal value. The pure metals are made into filaments for incandescent lamps, and targets for X-ray tubes. By their efficient use in alloys, the weight of automobiles is reduced, • and the wear and tear on tires and roads is thus minimized; in machine shops they help to give greater efficiency to tools and reduce production costs. Their development has marked a milestone in the progress of civilization. There has been considerable uncertainty regarding analytical methods for the rare metals. A great deal has been published, but the weak and the strong points of the various methods have not been investigated as carefully as is needed. The Bureau of Mines at its Rare Metals station in Colorado necessarily had to do a great deal of analytical work in connection with the metals covered by this bulletin, which aims to give the results of the experience so acquired. No claim for much originality is made, although some published methods given have been modified, and some new ones have been developed by members of the staff. The principal methods available were studied critically, and it is to be hoped that the work will assist those interested in analytical work in connection with the metals named.

Jan 1, 1923

By Ken Andromalos

Continued population growth combined with limited water resources in the Denver area has resulted in the conversion of a number of mined out gravel pits in the area into municipal water storage facilities. The use of slurry walls provides a cost effective means of isolating groundwater to convert these pits into efficient water storage facilities. Design considerations include: stability, underlying bedrock conditions, backfill mix design and earthwork requirements. Installation issues during construction include: trench stability considerations when excavating through relatively clean sand and gravel deposits in potentially high groundwater conditions; keying into three to ten feet of fractured claystone, siltstone or sandstone that makes up part of the Denver formation, and quality assurance procedures to assure a proper groundwater barrier is constructed. The paper concludes with two brief case histories to illustrate how these considerations are applied

Jan 1, 2007

By P. B. Kelleher

Most of the piers and other pile-supported marine structures in the New York City Harbor area were constructed prior to the widespread use of currently available pile protective systems. As a result, the support piling of many existing marine structures have experienced deterioration to an extent that their structural sufficiency is impaired long before the useful life of the structures they support is over. This situation presents special and unique problems of how to restore the structural integrity of these piles while at the same time allowing full use of the structures they support. Spearin, Preston & Burrows is a 100 year old New York City-based marine construction firm specializing in waterfront and foundation construction. In recent years it has undertaken and successfully completed several unusual projects in the New York City Harbor area involving the rehabilitation of existing, deteriorated piling underneath major, economically important marine structures. This work was accomplished using techniques that permitted full use of these structures. Several different pile rehabilitation systems were used, each having their own particular application to the deterioration problems of the piles supporting each structure.

Jan 1, 1989

By Paul M. Ambrose

THE ABRASIVES INDUSTRY throughout the world enjoyed a profitable year. With the exception of tripoli, the quantity of each kind of abrasive produced in the United States was greater than for any of the past 5 years and value of each was greater than for many years. Production of silicon carbide both in the United States and in Canada was the largest since 1960. Abrasive machining, which offers great potential for the increased Use of aluminum oxide, contributed to increased industrial productivity. Diamonds from the sea off the coast of South-West Africa attracted wide interest. Much of the production from this source has been gem diamond, and there is little likelihood of significant quantities of industrial diamond from that source. Manufactured diamond from all free-world sources was sold in the United States in 1964.

Jan 1, 1965

By A. M. Hearn, J. G. Roos

Energy consumption, being a large proportion of the input of the ferroalloy production process, can be measured in terms of the efficiency with which the energy is utilized and the effectiveness with which it is used. The efficiency of the usage of energy revolves around the specific consumption of the energy for the production of the alloy, which encompasses the thermodynamic aspects of the process and is more of a metallurgical function that will not be addressed further in this paper. The effectiveness with which the energy is utilized is determined by the optimisation of the electricity supply from the utility (in this case Eskom). The South African electricity supply industry is on the brink of considerable restructuring, implying changes in ownership, structure and regulation. In other countries, however, restructuring has often seen higher prices. Owing to the diversity of growth prospects in South African markets, Eskom is turning to new market management and generation strategies. In future, Eskom will develop pricing strategies to increase demand from attractive customer segments such as paper & pulp, iron & steel, aluminium, and other metallurgical industries. There will be a broader spectrum of product offerings, including dynamic pricing options and demand-side management incentives. In a future electricity market that will become more dynamic and demanding, it will become increasingly important for electricity consumers to optimise their electricity supply. There are many facets in optimising the electricity supply, which include optimal utilisation of the tariff, integrating energy cost management into the production planning process, implementation of demand-side management actions, modelling, scenario planning (.what-ifs?.), optimisation, maintenance scheduling coordinated with the tariff periods, etc. This paper gives consideration to the status of the development of technology at the manganese alloy works of Samancor at Meyerton, South Africa in order to increase the effectiveness with which energy is utilized.

Jan 1, 2004

By Garry M. Johnston, Matthew L. Sutcliffe, Nicholas J. Welham

"The predominant current processes for the treatment of oxidized copper–cobalt ores use a reductive acid leach to bring the desired metals into solution. However, the indiscriminate nature of acid leaching results in a solution, akin to a metal soup, containing not only the Cu and Co but also an extensive suite of other metals. These other metals, notably Fe, Mn, Al, Ca, Mg and Si, all have to be eliminated from solution before the copper and cobalt can be recovered. Generally precipitation processes are used, but these tend to result in significant losses of copper and/or more usually cobalt from solution, leading to reduced recoveries. The AmmLeach® process uses ammonia-based chemistry to selectively leach the target metals, leaving the rest behind in the leach residue. This approach eliminates any need to clean the solution of unwanted metals and the consequent metal losses. After solid–liquid separation, the leach solution is immediately subjected to separation and concentration of the copper and cobalt using solvent extraction and electrowinning. INTRODUCTION The Copper Belt extends through the northern part of Zambia and the southern province of Katanga in the Democratic Republic of Congo (DRC) and contains the richest and highest grade deposits of copper and cobalt remaining in the world. Whilst there are a number of mines that produce sulphide concentrates, using froth flotation, the largest deposits are those where near-surface sulphides have been weathered over time to form oxides. The oxides cannot be concentrated by conventional physical means to give high recoveries. Despite this, a number of dense medium separation plants have been installed and used to produce a higher grade concentrate which is typically exported (while the rejects, typically 2 to 3% Cu are stockpiled for treatment at a later date). These plants generally have low recoveries and can only be used on the dwindling supply of high grade materials. In exporting the concentrate, little value adding is undertaken within the country, thus greatly reducing the economic benefits to the country. Recent changes to the regulations in the DRC will effectively ban the export of low value ores, concentrates and intermediates in favour of high value metals. This will necessitate mines to install new processing circuits in order to comply with these regulations. The head grade of ores currently being treated in the DRC is slowly decreasing as the extremely high grade materials are being selectively mined out. In many cases, the removal of a small volume of high grade materials leaves a much larger volume of economically marginal ore behind. This is due to a desire for short-term profits overtaking long-term prosperity. The remaining ore, which in many cases is still of relatively high value by world class standards, is likely to be only treatable by low cost heap leaching. There are some initial trials of heap leaching within the DRC, but implementation at a large scale has yet to be adopted."

Jan 1, 2015

Jan 1, 1925

By John E. Kelley

A method for measuring the spark-shower radiance of metals when abraded on a grinding wheel was developed by the Bureau of Mines for evaluating the sparking tendency of metals. The radiance was measured in units of emissive power per solid angle per area of the detector. Over 100 metals were tested and rated relative to commercially pure iron. The metals tested included elemental metals, iron binary and ternary alloys, iron-carbon ternary alloys, commercial steels, nonferrous alloys, and a few hard-metal compounds. Some alloys were synthesized; others were obtained commercially. Alloys that possessed good strength properties were emphasized for selection. The results indicate that the spark-shower radiance of plain carbon steels and carbon alloy steels was greater than that of pure iron. Certain elements, particularly vanadium and chromium, reduced the sparking tendency of iron. Stainless steels and particularly nickel alloys displayed low spark-shower radiance. Some metallic elements had much lower radiance than iron; others, much greater. Plain carbon steels, heat treated to a variety of hardnesses, gave radiance values that generally increased with increasing hardness. The effect on sparking tendency of an increase in hardness of an alloy steel was studied. The sparking tendency increased with an increase in hardness to a maximum, then decreased with a further increase in hardness.

Jan 1, 1974

By Peter de Bakker

The objective of this contract was to develop a simple, reliable, economical, remote-control roof bolting module for installation of mechanical and resin bolts. It was to be capable of placing longer than seam height bolts, up to 10 ft lengths, from a seam height of 36 to 72 in., while keeping the operator under supported roof. The resulting machine, called REM-Bolter, is a low profile unit that utilizes Foster-Miller Flexible Shaft Roof Drill, a Bendix Roof Bolt Inserter and a newly designed. Roof Bolt Lifter/Torquer. Every effort was made to strike a compromise between complete automation and complete manual control. In a controlled laboratory environment the REM-Bolter remotely installed 1000 bolts. Subsequently the machine was tested in an operating coal mine where 500 holes were drilled (and an equal number of bolts were installed) remotely, over a 4 month period. The results of all tests Live shown that the operator of a machine of this kind can quickly, and repeatedly, install rootbolts remotely from his operator compartment some 8 ft away from the drilling/bolting action. The report includes recommendations for improvements to the present REM-Bolter design that would translate the present test bed into a second generation test bed and a potential first generation production unit.

Jan 1, 1983

By Y. Wang, E. Forssberg, A. Johansson, B. Chan

A super-conducting high gradient magnetic separator with matrix vibration in dry separation mode is a powder purification device, which has been used to remove weakly magnetic impure particles from fine calcite powders below 53 µm in this study. A fundamental question concerned is the evolution of the matrix clogging under gas-solids loads. This paper presents the improvement of the separation selectivity using a method of mechanically based vibration on the matrix in the separator. The functions of the matrix vibration are discussed. The results indicated that the mechanically based vibration on the matrix within a high intensity magnetic field while a feed was introduced in an air stream, was found to be effective for the dry purification of fine powder materials.

Jan 1, 2001

By Thoedtida Thipparat

The diaphragm walls and barrettes are very important to the constructions of multi-storeyed buildings, elevated expressways, subway railway stations, etc. Uncertainties particularly increase in accordance with the construction progress. Overcoming uncertainties influences the construction goals including achievement of time. This paper is aimed at proposing an uncertainty assessment and delay evaluation model to assess uncertainties and evaluate delay resulting from those uncertainties. Neurofuzzy systems (NFSs) for assessing uncertainties and evaluating delays are developed. Artificial neural networks (ANNs) have ability for learning from the past data and generalizing outputs for the next applications which are provided for fuzzy logic systems (FLSs). FLSs have ability for exploiting the tolerance of imprecision and uncertainty. FLSs provide the reasoning to the ANNs. Uncertainties affecting each operation were assessed and delays were evaluated by following steps of the proposed model. The uncertainty assessment and delay evaluation approach was applied to a diaphragm wall and barrette construction to demonstrate how to implement the proposed model. The results of the test case application were used for handling delay at all operations regarding the corresponding uncertainties.

Jan 1, 2006

By R. L. Marek

The number of persons fatally injured in the California petroleum industry in 1931 was 30, a decrease of 20 fatalities or 40 per cent from the number killed in 1930. As a result of the decrease in the number of fatalities for 1931, the fatality curve of tie California petroleum industry reached its lowest point in nine years. Although reductions in personnel--which permitted the retention of a select and experienced class of workmen, decreased active field-development work, and curtailed production--undoubtedly have had a marked effect on reducing the number of fatalities in 1931, the decrease also has resulted from continued accident-prevention efforts. Statistics show that a direct relationship exists between development activity and the number of men accidentally killed in the drilling and producing division of the California petroleum industry. For example, when the average number of drilling wells in 1930 was 29 per cent less than in 1929, the number of men accidentally killed at drilling wells dropped 48 per cent; and when the average number of drilling wells in 1931 decreased 52 per cent from 1930, the number of fatalities at drilling wells decreased 58 per cent. The relationship between field-development work and fatality frequency is significant because each year at least 50 per cent of all the fatalities in the California petroleum industry occur in the drilling and producing division. This relationship should serve to guide the accident-prevention efforts of the industry, especially in the drilling and producing division, toward checking an increase in fatal accidents when development activity again takes an upward trend.

Jan 1, 1932

By J T. Woodcock, G J. Sparrow

A sample of pyrrhotite flotation concentrate pulp assaying 15.3 g/t Au, which had been prepared from an old tailing dump, was treated to extract the gold. Examination of the concentrate with an SEM showed that exposed or free native gold, 5- 40 ¦m in diameter, was present but no locked gold was observed. Direct cyanidation of the concentrate to extract the gold showed that the flotation reagents present inhibited gold extraction. A range of pre-treatments was used to overcome these effects. Direct cyanidation for 48 h extracted only 26 per cent of the gold, indicating possible contamination of the gold in the concentrate with flotation reagents. Pre-treatment of the concentrate pulp by aeration for 24 h, or by 72 h aeration with an addition of 3.65 kg/t of sodium sulphite, gave little improvement in gold extraction by subsequent cyanidation. Pre-treatment by filtration, or by aeration with 12.5 L/t 100 volume hydrogen peroxide, followed by cyanidation for 48 h gave gold extractions in the range 67-77 per cent. Combining filtration and an aeration period with hydrogen peroxide addition raised the subsequent cyanidation extraction of gold to 88 per cent, giving a tailing assaying 1.5 g/t Au. Re-cyanidation of some of the dried tailings from the initial tests extracted most of the remaining gold giving a tailing assaying 0.5 g/t Au. This indicated that most of the gold was available for dissolution by cyanide. The poor dissolution of gold by cyanidation of the untreated concentrate was attributed to the presence of flotation reagents. It was shown by UV spectrometry that xanthate-containing compounds were present in the solids fraction of the original pulp and that they were partly removed by pre-treatment. MIBC was also present, and dithiophosphate, which was used in the flotation step, was also probably present. The results indicated that the improvement in gold extraction after filtration and oxidation of the original pulp was due to partial removal of the flotation reagents, and illustrates the detrimental effects that residual flotation reagents can have on the extraction of gold by cyanidation of a flotation concentration.

Jan 1, 1990

By S. Kawatra, K. Lewandowski

Heap leaching efficiency is reduced by poor solution flow characteristics (channeling and ponding), which result from fines migration. Agglomeration of the ore can immobilize fines, but copper leaching requires an acid-resistant binder to stabilize the agglomerates. Until now, there has not been a satisfactory way to evaluate whether a binder was effective, other than squeezing a handful to see if it “feels right”. We have developed procedures to quantitatively determine whether a binder gives good performance in an acidic solution, and have identified several binders that will be suitable for copper heap leaching.

Jan 1, 2007

By H. C. Fuller

Rhodonite, a manganese silicate, occurs as an important component of extensive veins in the San Juan district of Colorado. Recent work by the Bureau of Mines has demonstrated that typical ores of the area can be upgraded to about 30-percent manganese content. Because of their siliceous nature, such concentrates require further processing to convert the manganese into more usable forms. The investigation described in this report demonstrates the technical feasibility of producing silicomanganese from a rhodonitic concentrate by electric smelting methods. The rhodonitic concentrate used in the smelting research was prepared by dry high-intensity magnetic separation of ore from the Silver Queen vein. The concentrate contained 29 percent manganese, 2 percent iron, and 41 percent silica. The principal minerals in the concentrate were 35 percent rhodonite, 30 percent rhodochrosite, and 25 percent quartz and chalcedony. Limestone was used as the flux and coal was used as the reductant. These minerals were crushed and screened to minus 1/2-inch plus la-mesh size.

Jan 1, 1962

By H. C. Seeber

When considering all the aspects of a viable mine plan, it is important to estimate the accurate cost of mine ventilation, which varies as a function of airway dimensions, fan selection and ventilation network. Optimization of the overall elements of ventilation design can lead to very significant cost savings when capital and operating cost savings are considered in combination. This paper will describe a methodology, whereby ventilation costs can be minimized by optimizing the ventilation aspects of mine design and fan selection, by providing a brief description on ventilation theory and the factors which affect ventilation operating and capital costs.

Jan 1, 2002

By H. S. Rathor

NTPC (National Thermal Power Corporation), a multi-unit organization, is generating 26% of India’s total power. This power is produced from its 14 coal based stations and 7 gas based stations. NTPC is entering into the business of power-distribution, power-trading, setting up of coal mines and diversification in non-conventional energy sector as well. For achieving the goal of the country “Power for All” NTPC has taken a giant stride by entering into Hydro Power generation which is also the cheapest and the cleanest renewable source of energy. In its pursuit for excellence, 800 MW Koldam Hydro Power Project is NTPC’s first venture in hydro sector. In Koldam, hydropower potential will be harnessed by constructing a 163m high earth and rock fill dam in a narrow gorge at upstream end of Bhakra reservoir. The river diversion is envisaged through two parallel, 14m finished diameter ‘horseshoe’ tunnels of length 901m and 934m at village Kian on the right bank, where the river forms a 180° loop. The diversion tunnels are designed to accommodate a flood of 6500m3/sec, taking into account the maximum probable discharge of 200 years return period. The tunnels pass through dolomite and limestone rock formations. The excavation of tunnels was done with drill and blast method. The excavation was attempted from both inlet and outlet faces. During geological investigation a rock fault was located at the outlet area. The location of the fault was such that it was passing through the edge of the Tunnel-1portal and around 30m away from the face of the Tunnel-2 portal. The quality of the rock at Inlet was also poor. To save the portals from slips, excavation of the tunnels was planned to start after the completion of the open excavation and its support system both at inlet and outlet. The tunnel excavation at inlet was envisaged by approaching the tunnels’ portal by constructing a road through 540EL bench and meeting the inlet portals on the upstream end, which would have been ready by mid2003, only after completion of the open excavation and its support system. To save time and cost, it was felt necessary to modify the planning by starting the tunnel excavation simultaneously along with open works both at inlet and outlet. The excavation at the inlet face of the tunnels started in December 2002 after rerouting the approach road to inlet portals through haulage road on the downstream and similarly Tunnel-1 at the outlet was started in the low cover area before completion of open area works. Thus the tunnel—heading excavation was started nearly 06 months early with the change of methodology.

Jan 1, 2005

Radioisotope x-ray methods for the on-stream determination of copper, lead, and zinc in mineral product slurries were developed, and were successfully tested at the plant of Cobar Mines Pty. Ltd.The tests were made in three stages. Measurements to determine the precision of analysis were made initially on briquettes of the mineral products. The effect of slurry solids content variations was then determined by measurements on the mineral products in a recirculating slurry loop. The radioisotope analyser was finally tested in a series of on-stream measurements in the plant.Copper, lead, and zinc in flotation feed and in copper concentrate were determined to a precision ranging between 1·4 and 15 per cent of the mean element concentration in the slurry solids. These precisions are within limits required for plant control purposes at Cobar.

Jan 1, 1971

By P. J. Gron

"The Samatosum Project is a base and precious metal deposit located in south central British Columbia. A dilute ore reserve of 766, 682 tonnes grading an average 1.1% copper, 3.0% zinc, 1.4% lead, 833 gram per tonne silver and 1.6 gram per tonne gold is available. The base metals occur as tetrahedrite, chalcopyrite, sphalerite and galena. Virtually all of the silver and gold are associated with the tetrahedrite.The mill is operated at a rate of 21 tonnes per hour. Sulphur dioxide is used as a zinc depressant in the grinding circuit. Production of a Cu/Pb/Ag concentrate is accomplished by conventional flotation. This concentrate is then separated into Cu-Ag and Pb concentrates through a reverse flotation circuit utilizing sulphur dioxide, starch and sulphuric acid as lead depressants.The tailings from the Cu/Pb/Ag circuit are treated with copper sulphate to activate the zinc. Production of a zinc concentrate is accomplished by conventional flotation. Dewatering of the concentrates to 6% moisture is done with a LAROX filter press.Tailings effluent is treated with lime and sodium sulphide to precipitate out the heavy metals. The resulting sludge is treated in OYNASAND sand filtration units to produce a quality effluent."

Jan 1, 1990

By N. Hmidi, T. Yalcin, M. Papadakis, B. Hilscher

Mill tailings, containing iron sulphides in particular, pose an environmental concern since they constitute a potential source of acid mine drainage which can damage vegetation, harm soil and living organisms, and contaminate groundwaters. Proper disposal of acid generating tailings is therefore an important issue that must be addressed and resolved in a satisfactory manner. Placer Dome Canada operates a 4000 t/d gold cyanidation facility at Musselwhite mine, in northwestern Ontario, where the mill tailings have been classified as acid generating. This study was conducted to explore the effectiveness of froth flotation in removing the sulphide minerals from these tailings and producing a low-sulphur, non-acid generating material that could serve as a capping material for previously deposited tailings. Laboratory semi-batch flotation tests were carried out in accordance with an experimental design procedure, and a computer simulation program was developed to facilitate the evaluation of flotation performance. In this investigation, pH, collector concentration, and airflow rate were considered as the relevant flotation variables, and their effects were examined both experimentally and by simulation. Results have demonstrated that flotation can successfully desulphurize the Musselwhite mine tailings and render them non-acid generating.

Jan 1, 2004