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By Louis W. Cope

INTRODUCTION Various methods for sampling placer deposits have been mentioned by Wojcik in Chapter 2. Here, a brief description and comparison of these methods will be given as related to bulk versus drill sampling. The advantages and disadvantages inherent to each will also be given. The means of sampling can be grouped into bulk or drill samples. As a generality, drill samples over a five-foot length will run from I/,, to 1 /, cubic yard, depending on the diameter of the drive shoe on the drill casing. Bulk samples can be expected to be in the range from one to many cubic yards each. SAMPLE METHODS Bulk Bulldozer-dug trenches and dozer or front-end loader pits are two methods to excavate large bulk samples. Smaller bulk samples can be obtained by digging small dimension shafts through the deposit, by hand or caisson-like drills. It is not recommended to split samples by alternate bucket-loads or by other means, as the effect of a nugget falling into one or the other fraction will seriously alter the sample.

Jan 1, 1992

The physico-chemical principles of chloride hydrometallurgy are reviewed to rationalise the complex chemistry in chloride-based processes for metal sulphides in terms of the predicted Eh-log[Cl-] relationships, measured changes in activity of H+, Mz+, Cl- and solubility of Ag(I), Cu(I), Cu(II), Pb(II), Ni(II), Au(III), Sb(III) and Bi(III). These changes reflect the nature of chemical speciation, competing effect of hydration/hydrolysis and chloro-complexation,composite effect of increasing acid and/or salt concentration and decreasing water activity. Rate data for the dissolution of PbS and ZnS in HCl containing Fe(III) or Cu(II) are compared and contrasted to highlight the effect of acid and chloride concentration, water activity, and the nature of oxidant. It is shown that LiCl, NaCl and HCl influence the kinetics of oxidative PbS leaching based on their effect on solubility of PbCl2 co-precipitated with elemental sulphur on the mineral surface. Evidence for the beneficial effect of Cu(II) in sulphide leaching is discussed.

Jan 1, 2003

By B. S. Butler

Apropos of metals low in the series illustrated by Dr. Butler's Table 11, it is interesting to note that Cress and Feldman29 reported traces of platinum metals in several samples of alunite. They found, chemically and spectrographically, several traces of platinum, palladium, and rhodium in alunite from Sugar Loaf Peak, near Quartzite, Ariz.; silver, platinum, and rhodium in alunite from Rio Grande County, Colorado; and traces of rubidium and gallium in various samples of alunite. These authors stated that the platinum metals appear to be present as Oxides and suggested deposition by hydrothermal solutions under near-surface conditions. AS described by Heineman,30 the wall rock of the Sugar Loaf alunite veins shows considerable alunitic alteration. Pyrite and hematite are relatively abundant in the wall rock but decrease progressively near the veins. Assays of samples of the Sugar Loaf alunite, run by J. B. Cunningham of the University of Arizona College of Mines, showed traces of silver and 0.002 to 0.004 oz of gold per ton, but the chemical form of the gold and silver in this occurrence remains undetermined.

Jan 1, 1957

In those days no one worried - there were plenty of other things to do. But in'these days it is different. Everyone worries- and. because there is so much worry, emotion has entered the picture. And, worse than that, capital is being made in political circles. People who were quite unaware, five years ago, that any problem existed, have now become experts on the subject, and shout to high heaven that something should be done - and yet they go on using the leaded high octane petrol they deplore so much. And even scientists, who should know better, adduce only such evidence as fits the argument in hand. And the Press is not without blame - some of its reportings is open to serious question, whatever may be the excellence of its motives. The point is made that one should know what one is talking about. And make sure that the evidence quoted is fact - and make sure too, that all the evidence is used, not only that which suita the argument.

Jan 1, 1971

By T. F. Petty

During 1935 there were drilled in North Central Texas 1071 wells, of which 565 were dry holes, 469 were oil wells with an initial production of 43,766 bbl. and 37 were gas wells with an initial production of 129,332,000 cu. ft. Production has been 14,180,042 bbl., or a daily average of 38,849 bbl. In Table 1 are listed the various pools of the district. Most of the smaller pools are of minor importance and are merely productive spots. Numerous other similar spots might have been listed as pools but their production is included in other fields. There are a few flowing wells but practically all of the wells are being pumped. The estimated potential is about 50,000 bbl. and the allowable production is based on the Texas Marginal Well Law. In Table 2, wildcat wells that have resulted in the discovery of pools or important extensions to old pools or that have contributed to the geological information of the area are listed.

Jan 1, 1936

By S Moradi

The thickener overflow of zinc concentrate, obtained from flotation process in the Angouran plant located in Iran, contains a large quantity of slimes which were transferred to the tailing ponds. These slimes have caused problems of storing and environmental aspects in the Angouran area. The objective of this research is to describe the extraction of zinc from these slimes by leaching method using sulfuric acid in pilot plant scale.Chemical analyses showed that these tailing materials contain 35 per cent of zinc. By XRD analysis, smithsonite is identified as the major constituent. Calcite, dolomite, and cerussite are found as carbonate minerals. A minimal amount of Zn occurs as hemimorphite. Quartz, kaolinite, clinochlore and muscovite are other silicate minerals in the slimes.In the optimal conditions, ie acid leach at pH of 1, temperature of 55¦C, reaction time of 120 minutes and solid-liquid ratio of 1:3 and neutralisation with Ca(OH)2 at pH = 4.5, temperature = 70¦C, time = 90 minutes, the total recovery of zinc obtained was 95 per cent.

Jan 1, 2004

By Xiaorong Liu

Interfacial emulsion generated in copper solvent extraction is an inhomogeneous O/W emulsion that consists of organic phase, aqueous phase and solid particles. In order to determine what kind of components in organic phase promotes the emulsion, the organic phase separated from the interfacial crud provided by Dexing Copper Mine in Jiangxi, China was analyzed for its components by combined gas chromatography-mass spectroscopy. It was found that many kinds of emphiphiles containing such hydrophilic groups as carbonyl, carboxyl, or acylamine existed in organic phase, most of which were originated from the reagent degradation. Conclusively, Lix984N would degrade gradually during a long-term contact with the acidic aqueous feed and strip reagents. Lix84 and nonylphenol, as effective components of Lix984N, degraded almost completely after long-term recycling. As a result, the effective components of Lix984N were far lower in concentration than the dense-aromatic impurities derived from the diluent and the degradation products in total. The degradation of Lix984N would deteriorate solvent extraction, disengagement performance and result in more serious interfacial emulsion.

Jan 1, 2006

The library of the above-named Societies is open from 9 A. M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should he made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 11, 1918

By J E. Everett

At BHP Billiton Iron Ore Newman Joint Venture (NJV) ore is railed from four separate mine operations in the Newman area to Port Hedland, where the ore is screened, crushed and blended to produce lump and fines NJV products. Each mineÆs grade varies separately, so it is important that a centralised system is in place to control the overall blend and ensure that the products meet customer expectations. It is important that grade- related decisions are built into the normal production process and have minimal impact on production rates. A continuous stockpile management system (CSMS) covering the whole NJV production process is used to generate the daily crushing schedule, taking into account all currently available ore sources. Innovative additions to the CSMS provide more accurate information to support decision making by the mine schedulers; for example, blasthole estimates are continually adjusted for bias compared to crusher and port rake grades; lump-fines (L-F) grade split and beneficiation plant upgrade algorithms are updated on a continuous basis, and the dilution effect, which impacts on reported port rake grades, is removed.

Jan 1, 2007

By D K. Joyce, B Mohanty

In a previous paper, it was shown that a lack of clear understanding of the role of initiation mode on detonation characteristics often leads to under-utilization of the explosive system in blasting. This is of particular significance since the very large number of explosive initiation practices currently in use implicitly assumes that the blasting performance of an explosive is largely independent of the exact mode of initiation. This paper deals specifically with bulk-loaded and pneumatically-loaded ANFO under various initiation modes in small diameters. These include initiation by booster and detonating cords of various strengths, and combination of cords and boosters. The nature of energy release and energy partitioning between shock and gas energy have been studied in the underwater test as a function of charge diameter. The paper describes the relative merits of various initiation modes for specific charge geometries and confinement, under end- and side-initiated conditions. Guidelines have also been formulated for use in the field to match initiation practice with blasting requirements.

Jan 1, 1994

By S. K. Kawatra, S. J. Ripke

During iron ore pellet production, bentonite clay is used as a binder. Typical pellet plants spend from $3 million to $5 million annually for the clay. If bentonite dosages could be reduced by using it more efficiently, a significant cost savings would result. If the binding mechanisms can be completely understood, procedures can be developed to use bentonite more efficiently. Classical bentonite bonding theory is based on the behavior of bentonite at low percent solids and high mixing shear rates. Under these conditions, bentonite was understood to expand, disperse into platelets, and dry into a bonding "film" or "gel." However, these are not the conditions that exist during pelletization, which is carried out at high percent solids and relatively low shear rates. In this paper SEM imaging was used to identify and explain the bonding mechanisms of bentonite on the surface of magnetite concentrate. It was determined that bentonite would form a fibrous network under the proper conditions and that the formation of these fibers corresponded with an increase in the bonding of particles by the bentonite.

Jan 1, 2000

The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will he sent more promptly and in more usable shape.

Jan 9, 1917

The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 3, 1918

It is well to bring before you again the chief purpose of the National Research Council and of this its Division of Engineering, to stimulate others to make researches rather than to make them ourselves, because a given amount of our energy spent in inciting others will accomplish far more than if applied in executing them ourselves. This is because there are scattered through the numberless governmental, educational, and industrial laboratories of the country a very great number of investigators not only capable of being stimulated, but willing to aid in cooperative broadly planned research rather than to follow the haphazard methods of the past. Taken collectively, these laboratories and their personnel can produce an annual crop of knowledge the value of which is of the order rather of billions than of millions of dollars. I invite you to regard this potential product as a crop, to be planned, fertilized, harvested, and distributed with the sane order of statesmanship, the same breadth of view, with which we treat any other great human product or achievement, whether agricultural, industrial, or transportational.

Jan 1, 1919

By Saurabh Rastogi, Vikram Shishodia, B. Pitchumani

Comminution is a unit operation which consumes major part of energy in mineral processing industries such as fertilizer production. Ball mills are widely used for size reduction of a given ore to the liberation size that is required in further beneficiation processes. In grinding of materials much effort is concentrated on control of top size of the product and this results in production of fines, also creates secondary problems of pollution due to the difficulty in the collection of fine particles. The present work has been carried out to control product size distribution for rock phosphate grinding in an Industrial Ball Mill of 600 TPD. The plant data are taken for a given feed distribution and mill operating conditions. The information at various Ball Size distributions are collected. The comminution functions such as specific rate of breakage and breakage distribution functions are estimated by back calculation technique to solve the mass balance equation. A simulation program is written to study the product size distribution obtained for various ball size distribution.

Jan 1, 1993

By D. C. Shelton, C. S. Ek

Corneille S. Ek (Assistant Professor in Ore Dressing, University of Liege, Liege, Belgium) — This is a very valuable paper, in that it shows how it is possible to take care of a multitude of laboratory routine tests, and derive from them successful modifications of flowsheets or of operating methods. The author and the Company appear to be test-minded and this is best seen through the case histories described. There are however some corrections to be made, and questions arise when one studies the paper. If all the equations are to be homogenous, one obviously has to write Eq. 4 On the other hand, it is difficult to accept the definition put on Eq. 7, for that equation, which represents the factor of transformation from tpd of solids to cu ft per min of pulp in Eq. 6, has nothing to do with conditioning. It is evidently assumed here that conditioning means, as Gaudin calls it,' modulation of collection. One would prefer, for Eq. 7, the appel-ation "pulp conversion factor". Eq. 8 and 9, giving the amount of reagent to be fed

Jan 1, 1965

By Robert J. Auber, Thomas R. Scotese

The West Leg Interceptor is part of a new sanitary sewer system in the southwest suburbs of Cleveland. The first two construction contracts were excavated in glacial soils varying from hard tills to pressurized silts and flowing sands. These soil and groundwater conditions were locally problematic during shaft and tunnel excavations and final lining construction. A variety of solutions were developed primarily during construction. During the WLI-1R Contract, subgrade pressures, continued ground losses, and displacements necessitated extra eductor wells and modified inverts for stabilization of shafts. At the WLI-2Contract, one shaft excavation in similar ground required only one extra well. In the WLI-1R tunnel, localized inflows of groundwater, silt, and sand through the geotextile fabric were stopped by cement grouting. In one WLI-2 connector tunnel, damage to the TBM flood doors combined with wet, flowing silt and sand led to ground losses, surface settlements, plugging, patching, and chemical grouting. The concrete lining in the main WLI-2 tunnel required remedial work to improve watertightness at joints.

Jan 1, 1999

By Michel Carreau

Renewable assets have large upfront capital costs but minimal operating expenses over their lifetimes. In some instances, deals can be structured so that direct capital investment is feasible, with paybacks typically within 5-7 years. In others, the burden of renewable CAPEX must be removed in order to create an attractive alternative to fossil-fuel-fired generation. Hatch has designed and oversees the construction of a renewable installation, which is financed, owned and operated by a special-purpose entity. Renewable energy is then delivered to the mining company via a customized power purchase agreement at a price that is lower than the levelized cost of fossil fuels. In this way, the mining company removes the burden of the renewable energy CAPEX from its balance sheet, thus freeing up capital, decreasing risk, and making the predictable, lower cost of renewable power more attractive than the variable cost of fossil fuels. This paper presents the above business model and success stories of hybrid power at remote sites (wind and solar coupled with diesel engine).

Aug 1, 2013

By J. B. Scuffham, G. A. Rowden

The use of ammonia as a leaching agent has been well-documented but only recently have its advantages been fully exploited on a commercial basis. When compared with conventional sulfuric acid leaching processes, the major advantage of ammoniacal systems is their ability to reject iron and many acid consuming gangue materials. Although metallic copper, nickel, zinc, etc. are dissolved rapidly in ammoniacal liquors at ambient temperature in the presence of air the sulfide ores of these metals are more resistant to this treatment. Sherritt Gordon Mines in Canada treats sulfide concentrates at its Fort Saskatchewan plant under pressure with ammoniacal am- monium sulfate solution to solubilize the non-ferrous metal values. Typical leach operating conditions are 80-95°C and 115- 128 psig. Although the metals present in the ammonical solution could be recovered via solvent extraction techniques, Sherritt Gordon Mines currently operates a pressure reduction process using hydrogen to yield metal powders directly from the ammoniacal solution. The basic Sherritt Gordon technology has been applied world wide for the treatment of nickel/cobalt concentrates.

Jan 12, 1973

By Thomas P. Meloy

A brittle solid broken by crushing or impact, results in a mass size distribution curve having a straight line segment when plotted on log-log paper. Depending on the mineral, the slope of this straight line segment ranges from a maximum of one for materials like glass and quartz to values of one half or less. Theoretical derivations of the size distribution, such as the Gaudin-Meloy model, yield a slope of one and only one. When the Gaudin-Meloy model is modified to assume that not all cracks terminate on a preexisting surface, the new model predicts that size distribution slopes, depending on the type of brittle solid, will be less than one. There is a measurable physical parameter that will predict the slope. In addition the model predicts that particles from such a size distributions will have negative corners and peaks - indentations. Moreover the model predicts that particle shape will systematically change with decreasing particle size. Finally, this new physical model of comminution may be experimentally tested.

Jan 1, 1995