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By John Ralston, Jona Addai-Mensah, Patience Mpofu

The flocculation and dewatering behaviour of kaolinite (non swelling) and smectite (swelling) clay dispersions has been investigated using hydrolysable metal ions Mn(II) and Ca(II) and anionic polyacrylamide-acrylate copolymer (PAM) at pH 7.5 and 10.5. A pH-dependent, specific metal ion adsorption behaviour, accompanied by a marked reduction in particle zeta potential and slurry shear yield stress, was observed to have a profound influence on the colloid stability of both types of clays. Due to the differences in the cation exchange capacity, the smectite clay dispersion required a higher amount of metal ions than kaolinite dispersion to produce similar effects. The adsorption density of the anionic PAM at the negatively charged clay particle surfaces correlated well with metal ion hydrolysis and adsorption behaviour, all of which had a strong effect on slurry settling rate and extent of consolidation. At pH 7.5 where Mn(II) ions hydrolyse, metal ion and flocculant adsorption densities were both greater in the presence of Mn(II) than Ca(II) ions. At pH 10.5, however, where Ca(II) ions begins to hydrolyse, higher adsorption densities were observed for Ca(II) ions in comparison with Mn(II) ions, as the latter hydrolysed completely and precipitated. The metal ion mediated flocculant adsorption led to improved hydrogen bond driven particle bridging and facilitated charge neutralisation flocculation mechanisms which significantly enhanced the dewaterability of both clay dispersions.

Jan 1, 2003

By C M. Ramotsabi, F Bornman, W Erasmus

Spiral concentrators are gravity based separation devices used for the preparation of coal, iron and heavy mineral ores (Wills, 1992). Gravity concentration remains the main separation method for fine iron ore and is used extensively for treating many minerals. Gravity concentration methods separate minerals of different specific gravity by their relative movement in response to gravity and one or more other forces, the latter often being the resistance to motion offered by a viscous fluid such as water or air (Wills, 2006).The main operating variables for a spiral concentrator are the feed rate, the slurry concentration, the wash water addition and the position of the splitters used to separate the tailings, middlings and concentrate streams (Sadeghi, Bazin and Renaud, 2014). Wash water is an important control variable used to wash away entrapped light minerals from the concentrate stream (Burt, 1984; Bouchard, 2001). Sadeghi et al concluded the spiral operation to be sensitive to the wash water flow addition and resultant economic trade-off. Increasing the wash water flow rate increases the concentrate grade at the expense of the iron recovery.The paper addresses the effects of dripping wash water onto the concentrate stream of a spiral processing fine iron ore. The dripping wash water system offers a low flow alternative and could possibly provide a good balance between grade and recovery of valuable minerals without using excessive water. The Multotec SC20HC/7 WW spiral was used for the experimental test work. The spiral was tested at varying solids concentrations; the wash water rate and the splitter positions were kept constant.The use of wash water at 30 per cent, 35 per cent and 40 per cent solid concentration improved the Fe grade in the concentrate by about 1.5 per cent, six per cent and eight per cent respectively. The additional SiO2 rejected by the wash water is approximately three per cent, nine per cent, and 11 per cent at 30 per cent, 35 per cent and 40 per cent solid concentration respectively. Addition of wash water is shown to have minimum effect on grade at 30 per cent solid concentration, and Fe upgrades obtained with and without wash water were found to be similar. Notable upgrades were observed at 35 and 40 per cent solid concentration with wash water. The results obtained suggest that the additional SiO2 rejection by wash water increases with an increase in solid concentration. This suggests that the benefit of using the drip system is notable at higher solid concentration. It is believed that at lower solid concentration SiO2 particles are reasonably free to move around and are possibly less entrapped than at high solid concentration.The Fe grade/recovery and solid concentration relationship with wash water showed a non-linear correlation. The Fe grade increases with an increase in solid concentration up to a somewhat optimum point and then drops as solid concentration increases further. The recovery of Fe on the other hand follows a converse relationship with solid concentration, the recovery decreases from 30 per cent to 35 per cent solid concentration and then increases again at 40 per cent solid concentration. The increase in recovery at higher solid concentration could possibly be explained by the fact that the mass yield to concentrate also increases with solid concentration. Since recovery is a function of both grade and mass yield, the higher recovery at 40 per cent solid concentration is likely due to the high mass yield obtainable at 40 per cent solid concentration.The drip system could therefore possibly offer a safe guarding against grade and solid concentration variations without using excessive water, and possibly ensure that a product within specification is maintained.CITATION:Ramotsabi, C M, Erasmus, W and Bornman, F, 2015. Optimisation of wash water on an iron ore spiral to improve grade, in Proceedings Iron Ore 2015, pp 175–184 (The Australasian Institute of Mining and Metallurgy: Me

Jul 13, 2015

By Lane, K. S.

The problem of stability of slopes in reservoirs is one of real interest in civil engineering. The problem is whether the valley walls will remain stable or whether they are likely to slide as conditions are changed by storage of water in the reservoir. If major slides are indicated, as on the walls of relatively steep canyons, one must estimate whether they will be so located and of sufficient size as to interfere with operation of the reservoir-as by blocking the outlets, or by displacing sufficient water to over-top the dam in a huge wave. Some cases involve problems in soil mechanics for slides in earth or weaker rock; other locations need the assistance of rock mechanics for slides in harder rock. While this is not a new problem, attention has recently been focused on its importance by the hugh landslide into the Vaiont reservoir in 1963, which claimed the lives of over 2000 people and forced abandonment of the dam and powerhouse.

Jan 1, 1969

By Weiguo Xie, Malcolm Powell, Lian Liu, Ping Yu

"In order to develop a common mathematical and simulation platform for tumbling mills, a review of existing mechanistic models was made identifying the key aspects of grinding and slurry transport which are common to all tumbling mills. A mill model structure has been developed for all types of tumbling mills based on the population balance framework by incorporating breakage characteristics, slurry and solids transport, product classification and discharge, and energy consumption. A size-dependant breakage model developed by the JKMRC is applied. Transport is separated from breakage events and treated as a main sub-model in the new model structure. The model structure is based on dynamic time-stepping technique to enable dynamic simulation capability for non-steady-state simulation and control modelling. It is envisaged that the new model will cover a full range of milling conditions. It should enable a smooth transition between different mill types, such as from AG (Autogenous Grinding) to SAG to ball mill. The dynamic mill model structure developed here is the first step towards mechanistic modelling of grinding mills and provides great potential for the optimization of the comminution process."

Jan 1, 2014

By Adegbenjo Adewale Oladapo, Ibitoye Simeon Ademola, Ladiipo Olufemi Akinbiyi, Adegbola Adekunle Amos, Adeboje Taiwo Bode, Raji Fatai Olasunkanmi

The combined effects of the addition of Silicon (Si) as alloying element and low temperature annealing on the tensile properties of 70/30 brass with Nickel (Ni) and Iron (Fe) contaminants is investigated in this paper. Melts of cartridge brass were made to which 0, 0.5, 1, 2, 3 and 4 wt % of Si was added. These were sand cast into rods of 600 mm by 10 mm diameter and were thereafter machined into standard tensile test samples. Some of these samples were annealed in a muffle furnace at temperatures of 250, 300, 350, 400 and 450 oC respectively and the others were used as control. Subsequently, all the heat treated and non heat treated samples were subjected to tensile tests on a Hounsfield Extensometer and the load – extension plots retrieved were analyzed. Microstructural characterizations of the samples were carried out using Accu-Scope Optical Microscope. The results showed that cartridge brasses subjected to alloying and annealing treatments had improved tensile and yield strengths. However, the tensile properties were increased and maintained within acceptable limits at stress relieve annealing temperatures.

Jan 1, 2015

By D. Hamilton

The electrode of a PEM fuel cell consists of two distinct sections - the catalyst layer and the porous transport layer (PTL). There are several kinds of PTL material, although all use carbon fibres as the solid fraction. The fibres can be matted to form a paper, woven into a cloth, or chopped to form a felt. Despite the different morphologies of the media, they are all anisotropic in structure, that is the majority of continuous fibres lie perpendicular to the direction of bulk transport. Currently, no models account for anisotropy and all transport coefficients are calculated as volume weighted averages or from empirical correlations (not developed for fibrous porous media). The present work presents a new methodology for determining anisotropic transport coefficients in fibrous porous media. A numerical experimentation process is employed wherein random samples of the PTL are generated and used to solve a diffusion transport equation. Effective transport coefficients are determined by integration of flux across the domain boundaries once a steady state solution has been reached. Multiple random samples at each porosity are generated in order to predict statistical variance. The results are correlated for ease of implementation in full PEM models.

Jan 1, 2005

By John C. Stankus

The 3 Right pre-developed longwall recovery entry at Signal Peak Energy?s Bull Mountain No. 1 mine was designed to prevent the abnormal roof conditions encountered in its firsttwo recovery entries. Unique geological conditions, such as the low overburden of approximately 200 feet and prevalence of roof joints in the sandstone overburden, contribute significantly to abnormal conditions during longwall recovery. The 3 Right recovery entry was 42 ft wide and developed in two stages, 21 ft wide in each stage. The entry roof was reinforced with steel wire mesh/non-metallic recovery mesh, high-capacity primary bolts and cables. After all the support was installed, the entry was completely backfilled with specially designed, cuttable, low-density cement. The roof bolting and backfilldesign were based on current practices in this mine and successful practices in other mines in the U.S. and Australia. Extensive instrumentation was installed in the recovery entry for continuous monitoring of load transfer as the face approached and cut into the recovery entries. The support design was completely successful with a smooth cut-through on January 29 and 30, 2014, significantly reducing the shield recovery time and meanwhile protecting the safety of miners. Based on actual observance and practices of the 3 Right recovery entry, recommendations on improvement and modificationsof roof support for 4 Right recovery room are presented.

Jan 1, 2014

By H. C. Burghard, F. R. Brotzen

Experiments were performed to determine the effects of mechanical vibrations on ordering in CuAu. The effects of 5, 10, and 15 kc vibrations were investigated over a range of ordering temperatures of 280° to 360°C. A decrease in the rate of ordering was observed at all frequencies and ordering temperatures. THE effects of mechanical vibrations on certain solid-state reactions have been noted by several investigators. In 1930, Mahoux' reported a substantial increase in the case depth of a steel sample nitrided under the influence of mechanical vibrations over that of an unvibrated sample. Similarly, an accelerating effect of vibrations on the diffusion of chromium in steel was noted. Guillet, in the same year, confirmed the results of Mahoux. More recently Schenck and schmidtmann3 studied the effects of low-frequency, alternating loads on the diffusion of carbon in steel. The results of their experiments, conducted at 500 cycles per min and large strain, (0.2 pct), indicated an acceleration of the process. These workers also reported an increase in case depth of a sample vibrated at 430 kc during a carburizing treatment. Effects of high-frequency vibrations on solid-state reactions have also been investigated by Gudzoff and Gavze6 and Fairbanks and Dewez.7 The former reported an acceleration of the age-hardening process in aluminum alloys. The latter noted changes in the structure and mechanical properties of steel annealed under the influence of vibrations. On the other hand, Altenburg4 and Ehringer5 have given some theoretical reasons and experimental evidence as to the improbability of any effect of vibrations on diffusion. Comprehensive surveys of the effects of vibrations on metallurgical reactions are given by Hiedemann' and Bergmann.9 None of the above investigations led to a physical description of the effects of mechanical vibrations on solid-state reactions. In the present study an attempt was made to gain an understanding of the influence of vibrations on nucleation and diffusion. The order-disorder transformation was chosen for investigation since its mechanism has been extensively discussed in the literature. Moreover, the progress of the transformation may be easily followed by observation of electrical resistance changes. EXPERIMENTAL PROCEDURE The specimens used for the experimental observation of ordering rates were prepared from 50 at. pct Cu-Au alloy wire.* Each specimen consisted of a 0.02-in. diam wire approximately 10 in. long to which two copper potential leads were silver soldered, 2 1/2 in. apart, near one end of the wire. A 1/8-in. diam by 1/4-in. long steel stub was silver soldered

Jan 1, 1960

By G. A. Moore

A brief review is given of methods designed to produce metallic iron of high purity, and typical results are listed. A recent method, utilized at the National Bureau of Standards, consists of the extraction of ferric chloride by ether, reduction of this ferric chloride to ferrous chloride, further purification of this chloride, and the subsequent electrolytic deposition of metallic iron. iron produced by this procedure apparently is softer than, and otherwise different in properties from, any iron previously prepared and contains appreciably smaller amounts of impurities. THE history of attempts to produce "pure" iron reaches to antiquity and it may be presumed that each ancient armorer who succeeded in making a better steel concluded, correctly, that he had done a better job of removing the "base metals," and incorrectly, that he now at last had a "pure" metal. Early metallurgical papers mentioned use of "pure iron" in making alloys—this "pure" iron in most cases being inferior to some commercial stocks of the present time. Improvement has been continuous, and usually at a sufficient rate to convince each succeeding group of workers that they, at last, were using the really pure metal (until the analysts also improved their techniques to again discover the impurities). These adventures were reviewed in some detail by Cleaves and Thompson.' Although the ores of a metal may be abundant, difficulties in extracting it may make the pure metal very rare. When impurities are restricted to a total of a few parts per million, nearly all pure metals become rarities. Lead, copper, gold, mercury, silver, zinc, aluminum, bismuth, and the six platinum metals are claimed to be available with total impurities ranging from 2 to 50 ppm. The present small and scattered world supply of so-called "pure" iron holds an unimpressive place in another group of 16 metals having approximately 100 ppm of foreign material. Of about 20 less rare metals, only the platinum metals are more costly to prepare. While the production of such rare varieties of iron may appear insignificant in the presence of thousand-ton operations with 95 to 99 pct metal, it must be emphasized that all researches on commercially interesting irons and steels are in fact studies of the modifications of the properties of iron by additional materials. Until the properties of high purity iron are directly measured, all ferrous research must operate without known base values. Traces of impurities may affect the properties of a metal in many ways. Infinitesimal traces of solutes, by disturbing the electronic configuration, greatly change the electrical properties of transistors and semiconductors2-3 and slightly larger traces might alter these quantities in iron. Soluble impurities which disturb the perfection of lattice arrangement not only may alter the magnetic constants and electric properties, but by their close association with dislocation phenomena probably control the very existence of the "yield point"; determine the value of yield stress; and perhaps control the selection of slip and cleavage planes. It has been speculated that impurities might even cause the allotropic transformation in iron, but in any case their rearrangement must contribute to the unreliability of heat capacity and other thermodynamic measurements. Impurities which do not remain in solution may cause even greater effects on the properties. Microscopically visible amounts of phases other than ferrite can be found in all high purity irons which have come to my attention. It can be calculated that from 50 to as little as 2 ppm of an insoluble material might be sufficient to completely film all grain boundaries in irons having grain sizes from ASTM Nos. 10 to 1. Should this occur, such films, even though invisible, may be very important in fracture problems, especially at extremes of temperature:' Studies of grain growth and diffusion normally imply consideration of a single-phase system, hence, in the presence of insoluble impurities they can be expected to give ambiguous data." High purity iron is also in demand for use as chemical and spectro-chemical standards; for work in classifying the lines of the iron spectrum; for biological work in nutrition; and for work in nuclear physics. where the presence of some sensitive

Jan 1, 1954

By James H. Owen

Because of price structure, ANFO is normally considered to be the most cost effective explosive used in quarry blasting. Results indicate that bulk smulsion can be more cost effective in applications where hole sizes range up to 6.5 inches in diameter while providing the simplicity of single product loading and storage. This can be accomplished without any fragmentation and/or movement loss usually in patterns which are about twice the size of ANFO patterns, allowing the combined drilling and blasting cost to be less when using bulk emulsions. Examples are presented supporting this concept using actual field results along with some simple calculations which take into account differences in the products such as density, matrix and detonation velocity.

Jan 1, 1998

By S. P. Sandoval

In 2002 the Freeport-McMoRan Technology Center undertook research to develop a lower-cost alternative to guar for cathode smoothing in copper electrowinning. The work was conducted at the Technology Center?s SXEW Test Facility located in Morenci, Arizona. Bench-scale copper electrowinning cells were designed and implemented to screen a number of potential polymers for cathode smoothing. These included modified polysaccharide polymers that were nonionic, cationic, and anionic in nature.

Jan 1, 2010

By A. Juganda, Jr. Bogin, J. Brune, J. Grubb, S. Lolon

"Face ignitions at the longwall face are a serious hazard in underground coal operation that can lead to a major mine explosion. Despite having methane monitoring system mounted on the shearer and at various locations on the longwall face, undetected accumulations of methane can still occur and result in face ignitions. With the use of Computational Fluid Dynamics (CFD), the interaction between the air flow at the longwall face and factors that contribute to the accumulation of methane around the longwall face can be modeled and visualized in great detail. The results confirm that the tailgate corner of longwall face is a critical area that is prone to face ignitions and needs to be properly monitored. The occurrence of roof falls on the tailgate entry inby the face and/or poor caving conditions behind the shields can pose a safety risk in the longwall operation. Poor gob caving can lead to insufficient face air quantity to dilute methane at the tailgate corner, while blocking of tailgate by a roof fall can carry methane contaminated air from behind the shields back into the face near the tailgate corner and pull the explosive gas zones (EGZs) inside the gob closer to the face. INTRODUCTION Ignitions of accumulated methane gas at longwall faces are well known to be among the major causes of methane explosion in underground coal longwall mining operations. Some of these ignitions can lead to major mine explosions, such as the Upper Big Branch mine disaster in 2010, in which methane migrated from the gob to the shearer cutting drum where it was ignited, resulting in a major mine disaster (Phillips, 2012). History has shown that, despite having methane monitoring systems mounted on the shearer and various locations at the longwall face and alarms set to 1% CH4 (Mine Safety & Health Administration, 2012), undetected accumulations of explosive methane-air-mixtures can still occur and result in face ignitions. Recent study by Verma and Brune (2016) state that frictional ignitions on longwall faces contributed to 379 incidents or 23% of the total 1,637 cases of face ignitions recorded from 1983 to 2014. The common cause of mine explosions usually involves poorly designed ventilation systems, insufficient ventilation, and inadequate monitoring in critical areas that are prone to methane accumulations. In longwall operation, the tailgate corner of the longwall face can be considered as one such critical area. On-site studies by Krog et al (2006) and Thakur (2008) show that increasing the longwall panel width may also increase cumulative methane emissions at the tailgate. There are also indications that increasing longwall face lengths can result in an increase of the void space behind the face under certain roof conditions (Schatzel et al, 2006). This may cause higher leakage rates from the face to the gob, thus reducing the amount of fresh air available at the tailgate."

Jan 1, 2017

Power plants that utilize conventional wet flue-gas desulfurization methods produce enormous amounts of flue-gas scrubber sludge. A typical 400 MW power station that burns a high sulfur coal produces 170,000 tons of wet flue-gas scrubber sludge per year. This scrubber sludge is currently landfilled at an enormous cost to utility companies. This material could be used as a raw material for industries that use gypsum, such as the wallboard and plaster industries. However, before it can be used as feedstock for these industries, some of the impurities such as unreacted limestone and silicates must be removed from the scrubber sludge. Froth flotation has tremendous potential for separating these impurities from scrubber sludge. In order to select an optimum flotation process, it is necessary to characterize the surface properties of the major components in the scrubber sludge, which consist of calcium sulfite, calcium sulfate, calcium carbonate (limestone), and silica. In this study zeta potential measurements were used to determine the surface charge of the components in scrubber sludge, with the goal of optimizing a froth flotation process to produce a marketable gypsum product for the wallboard and plaster industries.

Jan 1, 1996

By Ryoma Fujiyoshi

In this article, the technologies of highly durable MgO-C bricks for the scrap impact zone and bottom blowing tuyere of converters are demonstrated. On the bases of our recent investigations, wear of scrap impact zone and bottom tuyere are explainable in terms of crack initiation and propagation. Theoretically, crack propagation in brittle material is regarded as generation of new crack surface area. It occurs when the elastic strain energy stored in the material exceeds the energy required to generate a new crack surface area. Since the overall energy consumed for crack propagation until fracture is evaluated by fracture energy, materials exhibiting high fracture energy can be regarded as materials with high fracture resistance. Therefore, two fracture energy-improving technologies for MgO-C bricks were developed. One is matrix reinforcement and the other is carbon bond enhancement. These technologies were applied to bricks for the scrap impact zone and bottom tuyere. As a result of commercial applications, notable decreases in wear rates were recognized for high fracture energy materials for the scrap impact zone and bottom blowing tuyere of converters.

Oct 30, 2017

By D Matthews

Increases in mining and production capacities can have a major impact on the productivity of a mining and production facility during the construction and commissioning period. With minimised production loss in mind, a multi-phase modular plant design was implemented on the Khumani Mine in the Northern Cape, South Africa. The first phase involved a run-of-mine (ROM) crushing facility and the subsequent modular processing facility with capacity for 8.4 million tons per annum (Mt/a) product. An interim phase comprising modular additions to the processing facility increased capacity to 10 Mt/a product, with tie-ins occurring during maintenance periods. The second phase involves a second ROM crushing facility and modular additions to the processing facility, increasing capacity to 16 Mt/a product. This paper outlines the design considerations and limitations with modular design that need to be considered and shows how effectively construction and commissioning were implemented within shut-down and maintenance periods.

Jul 11, 2011

By Paula Ana Paiva

The high economic value and unique technological properties of the platinum-group metals (PGMs), plus their growing scarcity in the Earth’s crust, justify the crucial importance of developing recycling practices for PGMs end-of-life materials. Examples of top devices relying on the use of PGMs are automotive and industrial catalysts, and electrical and electronics equipment. This article critically describes the most recent research on the use of solvent extraction to recover one PGM, palladium, from spent catalysts. Some groups focus on the development of schemes involving commercial extractants, while others prefer to design specific molecules to efficiently and selectively recover palladium from these particular complex leaching solutions. Examples of commercial extractants proposed for the former schemes are Alamine® 308, TBP and LIX® 84I; while on the other hand, sulfur-containing diamides, thioamides, thiocarbamates, and dithioethers have recently been developed. Ionic liquids have to be mentioned too.

By Mostafa Sharifzadeh, Ebrahim Ghasemi, Kourosh Shahriar

"The Tabas Central Mine (TCM) is one of the underground coal mines located in the Tabas coal region, in the mid-eastern part of Iran. This mine is the first mechanized coal mine in Iran that uses the room and pillar method. Pillar design is one of the most important issues in underground coal mines, especially in room and pillar mining. In this paper, a new method for coal pillar design in the main panel of TCM is presented. This method is able to estimate the magnitude of the various loads (both development and abutment loads) that pillars might experience throughout the mining process. Also, the method reduces the pillar failure risk. Based on this method, proper pillar sizes in TCM are obtained (11.6 x 11.6 m (38.l x 38.1 ft)).INTRODUCTIONPillar design and stability are two of the most complicated and extensive mining problems related to rock mechanics and ground control subjects. Although these problems have been investigated for a long time, to date only a limited understanding of the subject has been gained. Prior to this, the dimensions of a pillar were largely determined by experience based on trial and error, intuition, or established rules of thumb; any research available tended to be isolated and sporadic. But nowadays, various pillar design formulas have been developed based upon laboratory testing, fullscale pillar testing, and back-analysis of failed and successful case histqries. In 1980, a number of ambitious field studies conducted by the U.S. Bureau of Mines developed the ""classic"" pillar design methodology. It consisted of three steps (Mark, 1999, 2006):1. Estimating the pillar load using tributary area theory2. Estimating the pillar strength using a pillar strength formula3. Calculating the pillar safety factorAlso, Bieniawski (1981) presented a step-by-step method to determine coal pillar dimensions in room and pillar mines. In this method, similar to the classic method, pillar load is estimated by using tributary area theory.Currently, in mqst of the room and pillar mines, remnant pillars in panels are recovered by retreat mining (pillar recovery). Hence, the above mentioned methods are not appropriate for pillar design, because in these methods pillar load is estimated by the tributary area theory, and the effects of abutment loads, which result from retreat mining and the creation of a mined out gob, are ignored. Abutment loads affect the pillars in the adjacent of pillar line and a load greater than what is estimated by tributary area theory is applied on the pillar. So, pillar design without considering the abutment loads leads to pillar failures during retreat mining. Pillar failures continue to be one of the greatest single hazards faced by underground coal miners. Pillar failures are responsible for unsatisfactory conditions, which include the following (Mark et al., 2003):"

Jan 1, 2010

J. E. Stead, Middlesborough, England (communication to the author): Prof. Howe's valuable paper on cast-iron brings forward most prominently the correct explanation of the part played by combined carbon in pearlite and cementite, in determining the strength and hardness of cast-iron. On a previous occasioil I have shown that castings made by melting a white Cleveland iron and glazed iron, one containing 1.5 and the other from 4 to 5 per cent. of silicon, and each about 3 per cent. of carbon, were stronger than those made of ordinary foundry-iron; the difference in the final castings being a differ-

Jan 1, 1902

By G. C. Nowlan, A. Illis, H. J. Koehler

At its iron ore recovery plant at Copper Cliff, INCO produces about 17 million pounds per year of a pure, acid-soluble, dense nickel oxide from nickeliferous pyrrhotite. The process used is also applicable to a broad range of ammoniacal nickel-bearing streams. The product has been widely accepted by the chemical, ceramic and electronic industries.

Jan 1, 1970

By Edward Keller

The work covered by this report was undertaken at the request of Dr. J. A. Holmes, late Director of the Bureau of Mines, to whom the writer had been recommended by C. W. Goodale and E. P. Mathewson, of Butte and Anaconda, Mont. The director's offer was accepted for the honor it conferred and for the useful results that might be promulgated by the work in the technical field covered. The investigation was facilitated by permission to visit various works and sometimes by contributions of important definite information on a given subject. It is therefore with pleasure that acknowledgment of courtesies is made to the following corporations and gentlemen: Anaconda Copper Mining Co., Raritan Copper Works, Baltimore Copper Smelting & Rolling Co., United States Refining Co., American Smelting & Refining Co., B. B. Thayer, A. C. Clark, A. L. Walker, William H. Peirce, E. A. Cappelen Smith, H. H. Alexander, F. C. Newton, S. Rolle, R. "V. Deacon, N. W. Pierce, O. C. Martin, C. N. Sappington, James K Thomson, W. G. Derby, and the assistants of the writer, K. 1V.McComas and W. L. Raup. In this report considerable space has been devoted to general and theoretical principles on the ground that under modern conditions the best results in any field of activity can be attained only with the aid of an adequate knowledge of the best theories underlying the practice. The diffusion of such knowledge in the field of sampling metallic metallurgical materials appears to have been quite insufficient, and it is felt that when the principles involved are once thoroughly comprehended their universal application will be appreciated, so that it will make no difference whether pig iron or gold bullion is offered for test. It may further be noted that a discussion of the theories underlying practical methods is placed under the caption "Practical Sampling," with the idea that no one can be a practical sampler unless he is capable of analyzing his methods. No attempt has been made to advocate anyone method, but it is hoped that the analyses of all of the methods in use will show where each may be correctly and safely applied. The fact that it is possible to demonstrate the theoretical correctness of several methods indicates the invalidity of the claim that any single one of them is the standard.

Jan 1, 1916