Search Documents

By M. du Plessis, D. F. Malan

"Crush pillars are designed to be in a crushed state whilst being formed at the mining face. The residual stress state of these failed pillars provides a local support function in mining stopes and is used in the majority of the intermediate depth South African platinum mines. On mines utilising crush pillars, the pillar dimensions are selected to achieve a width to height ratio of approximately two. This is not achieved in most cases as a result of practical mining problems and poor pillar-cutting discipline. Furthermore, pillar dimensions are seldom adjusted to compensate for the various factors governing crush pillar behaviour. The pillars should, however, be in a crushed state whilst being formed or whilst still in close proximity to the mining face to prevent potential damaging seismicity.An underground investigation was conducted into the behaviour of the crush pillars in a trial site on the Merensky Reef at Lonmin Plc. The aim of this investigation was to examine the mechanism of pillar crushing and the related rock mass behaviour. The underground test results and pillar behaviour are compared to a limit equilibrium model to investigate if the model provides a useful approximation of the behaviour of the crush pillars. This paper details some of the preliminary findings.INTRODUCTIONOn most mining operations, the design of crush pillars is based on trial and error. As the pillar strength is unknown, the pillar sizes are adjusted to obtain the correct behaviour. Crush pillar dimensions are generally selected to give a width to height ratio (w:h) of approximately 2:1, (Ryder and Jager, 2002). Several factors affect the behaviour of the crush pillars and in many cases satisfactory pillar crushing is not achieved. This results in a seismic hazard in many of the mines using crush pillars. If pillar crushing is not initiated whilst the pillar is being formed at the mining face, as the mining face advances and the pillars move to the back area of a stope, some pillars may burst while oversized pillars may punch into the footwall. If pillars are designed in such a way that they are fractured during cutting by the face abutment stresses so that the pillars will already have yielded and reached their residual strength, further compression of the pillars will be associated with an increase in load and stability will be ensured, (Ozbay and Roberts, 1988). The stiffness of the strata must therefore be greater than the post-peak stiffness of the pillar (Figure 1) or violent pillar failure and hanging wall instability will occur. The pillar design should be aimed at determining pillar dimensions for which the post-peak curve of the pillar is as flat as possible."

Jan 1, 2015

By J. G. Balkestein, J. W. R. Baerts

During an attempt to develop a method for accurate, rapid, continuous analysis of ash content of wal, the Dutch State Mines Laboratory found that the absorption coefficient for X-rays was related to ash content. This relationship was utilized in the development of an apparatus called CendreX, used to measure the absorption and in turn the ash content. The principle, procedure, accuracy, and applications of the CendreX automatic determination of ash in coal are discussed in detail. Until recent years coal preparation research was concentrated on the possibilities and efficiency of preparation equipment. Ever increasing demands for quality in coal, however, have caused researchers to become concerned with quality control. One of the characteristics strongly influencing quality (calorific value) and, consequently, the price of coal is ash content. Both customer and producer require that the ash content be controlled. To make this possible it is necessary for the producer to collect samples from the coal stream in the washery and to determine their ash content. On the strength of the results obtained the production process can then be adjusted, if required. Until recently incineration was the only method for determining ash content. When coal is incinerated with oxygen, it takes at least 15 min to determine the ash content. Even then some time may be lost in passing on the data. Therefore, this discontinuous and time-consuming method does not make a suitable starting point for checking, re-adjusting, or modifying the production process. Since it was not possible to accelerate incineration by mechanization and automation, another type of rapid continuous analysis had to be found. This would have to depend on some coal characteristic closely linked with ash content. At the Central Laboratory of Dutch State Mines, Dijkstra and Sieswerda found that the absorption coefficient for X-rays was suitable for this purpose. An apparatus based on the measurement of this characteristic was developed. Named CendreX,* this patented equip- *A Stamicarbon N. V. registered trademark. ment, used in combination with a sampler and conditioning apparatus, permits continuous determination of ash content with satisfactory exactness to within 3 min.t At the American Mining Congress meeting of May 1961, Log A. Updegraff, surveying aspects of continuous analyaia, reported on the CendreX appartus (Mining Congress Journal, August 1961). Since the first Condition for correct ash determination, whatever the method used, is always a sample taken in the right way, some practical aspects of sampling will be discussed first. SAMPLING In coal handling operations, each grain has its characteristic properties. In both the cross-sectional and longitudinal direction of the product stream the mixture of these grains is imperfectly blended. The elimination of the factor of segregation between the cross-sections from the direction of the stream is the principal aim of continuous analysis. Therefore, the samples to be analyzed are withdrawn in various places from the segregated product stream in such a way that they form a semi-continuous flow. In order to be truly representative of the product stream, the sample flow must fulfil two conditions: 1) The sample flow must be sufficiently large to insure that adventitious differences between the composition of the product stream and sample flow will be as small as possible. 2) All grains through the entire cross section of the product stream must have an equal chance to get into the sample flow. Since there is always a segregation through the cross section the sample flow will have a bias if the sampler collects only part of this section. In order to prevent the volume of the sample flow from becoming too large, the cross sections are taken discontinuously. However, this discontinuity gives rise to the adventitious differences that arise between the composition of product stream and the sample flow, and these differences become greater and are more deranging as the fluctuations follow each other more quickly. Moreover, the intervals between the morrnents of sampling mean a delay in the analysis. The aim will, therefore, be to collect small samples, or in other words thin cross-sectional increments, taken at sufficiently high frequencies. The following points should also be taken into account: 1) The smallest dimension of the openings in the sample collector must be equivalent to at least 3 d in

Jan 1, 1962

By S. C. Sircar, D. R. Wiles

The rate has been studied of the hydrogen reduction of nickel ions in acetate -buffered solutions, using a nickel catalyst. At temperatures between 130°and 160°C, the rate is found to be proportional to the catalyst area, the nickel ion concentration, and the hydrogen pressure. The effect of hydrogen ions is to reduce the observed rate, likely by causing the reverse reaction (dissolution) to proceed. The experimental activation energy was found to be 25 kcal per mole. THE precipitation of metals and lower oxides from solution by hydrogen reduction has been quite actively investigated during the past few years.1 In the case of nickel, the kinetics of the precipitation have been studied in ammonia solution2 but extension of this study to acid solutions has not attracted much interest, largely because of the unfavorable thermodynamics at all but the lowest acidities. For example, Schaufelberger foundg that only 10 pct reduction of nickel could be effected in sulphate solutions. One kinetic study of the reduction of Ni++ has been reported by Knacke, Pawlek, and Sussmuth,4 in which the order of the reaction was found to be one in nickel ion and one-half in hydrogen pressure. No mention was made as to the part played by the nickel catalyst, or by the pH of the solution. Moreover, the activation energy reported (4 .12 kcal per mole) is so low as to lead to some question as to whether diffusion might be playing a major role in determining the kinetics. We have recently completed a study5 of the kinetics of the hydrogen precipitation of nickel from acetate-buffered acidic solutions whose results confirm and amplify those of Knacke et al. EXPERIMENTAL PROCEDURES The work was done in a high-pressure autoclavee by the usual technique of removing small samples of the solution for analysis. Nickel analysis was done colorimetrically by the dimethylglyoxime method.' The catalyst used was carbonyl nickel powder (Standard A powder of the Mond Nickel Co., Ltd.) which was found to be composed of spheres of less than 350 mesh. The surface area of the powder was determined in this laboratory by the B. E. T. method to be 1.85 sq m (m2) per g. The catalyst was added to the solution only after the proper temperature and pressure had been reached. Agitation of the baffled system was by a turbine-type impeller, rotated at speeds between 400 and 750 rpm. The reduction rate was found to be independent of the stirring rate, so it was assumed that diffusion in the liquid does not limit the rate. In typical experiments, the nickel concentration was unchanged during an induction period of variable length. The concentration then decreased sharply, and gradually levelled off to approach the final equilibrium value. In some cases, notably at high stirring rates, the nickel concentration was found to increase considerably during the induction period, and then to decrease. In all cases, the rate was determined from the slope of the tangent to the rate curve as the concentration first decreased below the initial value. This is seen in Fig. 1. The rate measurements were found to be reproducible to within about 5 and to be quite independent of the nature or duration of the induction period. The range of conditions used is given in Table I.

Jan 1, 1961

By T. Fraszczak, U. A. Peuker, T. Mütze, T. Leißner, A. Wikedzi

The present paper highlights on the comminution and liberation properties of two greisen-type lithium bearing-mica ore blends (L1, L2) subjected to different breakage devices; cone crusher (CC), roller crusher (RC), rotor beater mill (RBM) and a screen mill (SM). The particle size distribution (PSD) of the products from each device were evaluated to search for an appropriate PSD model using Gates-Gaudin-Schuhmann (GGS) and Rosin-Rammler (RR) functions. In order to determine an appropriate function that could better describe the PSDs from the devices used, the coefficient of determination (R2) was used as a criterion. In terms of mineral liberation studies, due to costs, only products from rotor beater mill (RBM) were examined through an automated scanning electron microscope (SEM) technique. It was found that RBM, RC and SM products were better described by the RR model than the GGS model with higher R2 values (0.97-1.0). However, cone crusher products for L1 were better described by GSS model, while that for L2 were better described by RR model. In terms of the spread of size distribution as indicated by RR model parameters, RC products were more uniformly distributed compared to products from other devices, for both ore blends. Also the RBM products were more scattered than products from other devices. The results indicate that the composition of individual ore blends affected the comminution products PSDs since different PSD model parameters were obtained for samples comminuted by same devices. The modal mineralogy of the two ore blends indicate both to be rich in quartz, topaz, zinnwaldite and muscovite. Further, the result indicate that, for both ore blends, zinnwaldite phase is more enriched in the fraction < 250 µm. Moreover, better liberation of zinnwaldite is observed for L1 compared to L2. This could be explained by differences of the two ore blends in three aspects; the nature of mineral association, reduction ratio of the fractions analysed and the nature of spread of the size distribution.

Jan 1, 2018

By Kenneth J. Hartman

Introduction The term kaolin is derived from kauling, a Chinese word meaning high ridge. This was the name of a hill in China where kaolin was first mined several hundred years ago (Murray, 1976). Other common names used for kaolin include clay and China Clay. Clay technically has a broader meaning and could refer to bentonite and ball clay as well as kaolin. China clay, as a descriptive term, apparently results from kaolin&apos;s origin. But it could also be due to a significant historical use in ceramic applications. The terms kaolin and clay will be used interchangeably in this analysis because of the common practice of using these terms in the paper industry. Major reasons for kaolin&apos;s wide-spread industrial usages center on kaolinite&apos;s physical features of good color, low viscosity, and inertness. Kaolin is described as a hydrous aluminum silicate with an approximate composition of 2H2O • A12O3 . 2SiO2. A new version of the product is calcined clay with modified hydration content. It is gaining widespread use. Components of any particular kaolin, in addition to alumina and silica, are viewed as impurities. The more values deposits and, hence, higher priced kaolin products are those of the highest purity. Kaolin is the most widely used mineral in paper manufacturing throughout the world. Key production centers are located in England and the US. Most of the Tatter&apos;s production is located in Georgia. The key markets for Georgia kaolin are paper markets - both paper coating and paper filling. These paper markets extend throughout the world, not just to domestic markets. In fact, export markets are second in size only to domestic paper markets for Georgia&apos;s producers of kaolin. Just as the paper markets are important for kaolin producers, kaolin is an important raw material for papermakers. Compared to the other three major pigments - titanium dioxide, calcium carbonate, and talc - kaolin&apos;s 1984 tonnage for papermaking represented 85% of the total. Even though titanium dioxide&apos;s unit value is much higher, kaolin&apos;s estimated total 1984 value still represented 51% of total dollars spent by papermakers for the four pigments. Kaolin grades- are briefly defined using particle size and brightness as principal means of classification. Likewise, grades of papers using kaolin are defined using the American Paper Institute&apos;s guidelines. From these definitions, associated kaolin grades used in particular grades of paper are reviewed. Special emphasis is placed on how qualities desired in certain papers are achieved through the use of specialized kaolin grades. World kaolin production World production statistics (Coope, 1979; Table 1) demonstrate that kaolin is produced in many areas of the world. About 60% of production is centered in the US and England (Fig. 1). Deleting Eastern Europe&apos;s produc-

Jan 4, 1987

By Anders Sellgren, K. Hansson, A. Jedborn

In the mining industry, conversion of fine particles into a slurry is often part of the normal processing of the ore. Therefore. from a system&apos;s point of view, slurry transportation would be considered as a natural alternative, all the way from the working face to the final processing. In underground mines, there is sometimes a considerable inflow of ground water that has to be pumped out. When the mine dewatering installations are integrated with a hydraulic hoisting system, the cost of power needed to pump out the ground water can be excluded from the cost of hoisting, compared with other modes of transporting the solids to the surface. The chief advantage of hydraulic hoisting is that the hoisting capacity can be increased at comparatively low total cost without necessitating the sinking of new shafts. Alternative examples include deepening of the existing mechanical hoisting system, truck, or conveyor belts transport in ramps to the present level. These often become very expensive. The economic effectiveness of hydraulic hoisting and hydraulic design considerations have been discussed by Kostuik (1965) and Sellgren (1985, 1986) for both small shallow mines and large deep underground mines. Objective and scope The objective of this study was to demonstrate the feasibiliy of hydraulic hoisting in hypothetical examples of mine deepening. Underground grinding to a maximum particle size of about 700 um (about 25 mesh) is considered. The pumping of ground ore products with positive displacement plunger or membrane type of pumps at working pressures of up to 15 MPa (2200 psi) is a thoroughly tested technique (Venton, 1986). Hydraulic hoisting system A hydraulic hoisting system is described schematically in Fig. 1. The ore is mined, handled, and crushed conventionally. It is then ground wet underground. The slurry is then temporarily stored in an agitated tank and pumped to an agitated receiving tank on the surface. The ore is then further processed in the concentrator. The capacity of a pipeline is very high. For example, an annual production of 500 Kt (550,000 st) of ore can be handled in a 100-mm-diam (4-in.-diam) pipeline. Systems layout - economic effectiveness Schematic mine layouts are presented that represent situations where hydraulic hoisting often is the most economical alternative. A situation where the ore is trucked to the level of the existing hoisting system is shown in Fig. 2 (following page). With hydraulic hoisting, only a shaft for ventilation, pipe- line, and personnel are needed. In a first phase (Fig. 2). a hydraulic hoisting installation with crushing and grinding units, storage facilities, and pumps has been located at a level of about 400 to 600 m (1310 to 1970 ft) below the surface. With further development of the mine, the hydraulic hoisting

Jan 1, 1990

By Hillary W. St. Clair

Mining activity began in colonial times with ironmaking operations scattered along the eastern seaboard. Iron furnaces and forges manufactured iron implements from bog iron ores using charcoal from the extensive forests as a fuel. Lead ores were mined in the Mississippi Valley and copper ores in the Lake Superior region. However, the real beginning of the American mining industry did not occur until the 19th century. The history of American mining is organized around three epochal events. The first was the discovery of gold in California in 1848, which marked the beginning of a period of apprenticeship in mining and metallurgical techniques. The second was the discovery of the fabulous Comstock Lode in western Nevada in 1859, which expanded mining throughout the Far West and led to large-scale underground mining and the development of smelting techniques for lead, silver, and copper ores. The third event was the building of a transcontinental rail-road system after the Civil War, which brought about the consolidation of the industry from a large number of independent mines, mills, and smelters into integrated operations run by large corporations. Thus developed the mining industry that today supplies the energy and critical materials for the great-est industrial complex the world has known.

Jan 1, 1977

By D. Saramak

"High-pressure grinding technology is considered as one of the most efficient techniques of ore comminution, especially in terms of energy consumption. HPGR devices has been utilized in many mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Even though the technology well known (introduced into mineral processing circuits in 80’s), there are still examples of ineffective operation of HPGR devices. This is a result of improper application of HPGR into individual crushing circuit. The purpose of the paper was to analyze selected effects achieved in HPGR on the course and effectiveness of beneficiation operations. Investigations were carried out for copper ore, and investigative programme was run for different values of HPGR pressing force, as well as changeable ore characteristics (content of fine size fractions, material moisture). All crushing products were then treated in flotation process, in order to determine useful mineral recovery. Results of investigations show that HPGR operating pressure influences the metal recovery in proportional way, however too extensive pressure values have relatively lower impact on increasing of the metal recovery. Particle size distribution of HPGR feed and its moisture have lower influence on recovery level than HPGR pressure, but too extensive moisture content influences the higher energy consumption of the roller press, together with less effective comminution. The second aspect raised in the paper was a possibility to control and optimize the HPGR-based circuit. There were presented the proposed approach to adjustment of HPGR operating parameters that enables the higher metal recovery.INTRODUCTION The high-pressure grinding technology, invented and developed by Professor Schoenert in 70’s (Schoenert, 1979), is currently regarded as one of the most efficient methods of hard ore comminution. Since then the technology was introduced into raw materials treatment circuits in many mining and mining-related industrial sectors, including iron and non-ferrous metal ores processing (copper, platinum, gold), as well as cement and limestone flour production. Considerable number of works concerning modeling and optimization of HPGR operation were also presented (Daniel & Morell, 2004, Tavares, 2005, Saramak, 2012, Saramak & Kleiv, 2013). Nowadays high-pressure grinding rolls devices are considered as well know technology with over 500 sold machines, according to various sources."

Jan 1, 2018

Jan 1, 1941

By P. Au, R. Kearsey, D. Y. Seo, Patnaik. P. C.

Three nickel based superalloys (7.5%Cr+5%Co+2%Mo+1%Ti+5%Al and Ni balance (wt%)) containing different amounts of W and Re were produced in the single crystal (SX) condition utilizing the Bridgman casting process. First, the effect of different levels of Re, and W on chemical microsegregation were investigated by EPMA quantitative analysis, and eutectic phase fraction analysis. Second, in order to investigate the effect of these refractory elements addition on oxidation behaviour, isothermal oxidation testing of the SX nickel based superalloys was conducted at 1000°C for 277 hours under 3 ppm moisture content of air in a thermogravimetric analyzer (TGA). All three SX nickel based superalloys revealed an excellent SX solidification structure with a common primary dendrite arm spacing of -250 µm and a large fraction of ?/?&apos; eutectic located between the secondary dendrite arms. From the average EPMA compositional results, with the exception of Ni, elements such as Cr, Co, Re, Mo, and W all tended to segregate towards the dendrite core during solidification, while Al, Ti, and Ta were present in greater quantity in the last liquid phase to solidify, which resulted in large eutectic ?/? &apos; phases to form within the interdendritic regions. As the nominal level of Re increased, microsegreagation of Re, W, Cr and Mo increased, indicating that Re had a much greater influence on partitioning behavior compared to W. Figure la shows the specific mass gain as a function of exposure time for each alloy. An alloy with 2wt% of W and Re (Alloy B) exhibited less weight gain compared to two other alloys with either higher content of W or Re (Alloy A and C). Microstructural and compositional analyses of oxidized samples were conducted using SEM and EDS. Figure lb shows the typical surface morphologies of the oxidized Alloys A and B. It is evident that more oxide nodules (indicated by arrows in the figure) were presented in Alloy A. It is speculated that the amount of these nodules was responsible for more mass gain in Alloy A compared to the two other alloys. From the examination of the longitudinal section of the oxidized samples as shown in Figure 2, for Alloy A, nodules actually penetrated deep into the material. For Alloy B, however, a relatively uniform and continuous oxide layer was developed and deeply attacked areas were not observed. It was also found that preferential oxidized regions were located at the area between the ?/?&apos; eutectic phase and the dendrite arms where the concentration of refractory elements was relatively high. Therefore, it is plausible that the oxidation kinetics of these alloys is related to the extent of microsegregation.

Jan 1, 2004

More than in any other way, the community judges the minerals industry by its environmental performance. Minerals Council of Australia web site www.minerals.org.au/media/code Time is overtaking us. What was good enough yesterday is not good enough today. What may be acceptable today wonÆt be tomorrow. So we need to leap forward. We need to begin to move towards sustainability. Dick Zandee, Managing Director, Placer Dome Asia Pacific The competition for access to exploration and mining opportunities is intense. So is competition for the best people, capital and community support. Poor environmental performance damages a companyÆs ability to attract these. Quite simply, good environmental management is good business. Hugh M Morgan AO,Chief Executive Officer,WMC Limited. Decisions made by private industry and international corporations are increasingly determining the fate of the environment. ...Nothing could be more shortsighted than for todayÆs conservationists to neglect cooperation with business and industry as a means of moving company philosophy and public accountability ahead in favour of the environment. Dr Claude Martin,Director General,WWF International The four quotes above well illustrate the challenges faced by companies and conservationists in attempting to achieve the societal goal of sustainable development. That this aspirational goal itself is far from clearly defined, although it has been widely accepted and endorsed by governments, business and civil society, exacerbates the challenges. Sustainable development has as its central thesis the integration of environmental, social and economic policy. Its attainment by business has been described John Elkington (1998) as the pursuit of the ætriple bottom lineÆ - the achievement of social and environmental targets, in addition to the traditional economic bottom line. It is self-evident that business is both competent and comfortable defining and measuring economic performance and reporting that performance to internal and external audiences. As long as information has been prepared according to the established standards of measurement and reporting of economic performance, all audiences can have confidence in its accuracy. Business does not enjoy the same competence and comfort with regard to social and environmental performance. This is no startling condemnation of business, any more than it is a criticism of governments, non-government organisations (NGOs) or academia. It is a statement of fact that the tools to allow for credible definition and reporting against the other two components of the ætriple bottom lineÆ have yet to be fully developed and are, therefore, far from being widely accepted. Crucial to achieving sustainability is the ability to measure progress toward the goal. The task is to develop means to define appropriate performance standards and to credibly measure and report company environmental and social performance against those standards.

Jan 1, 2000

By R. E. Robbins, H. R. Brager

THIS note describes an unusual result obtained in an electron microscope investigation of cavities produced in commercial type 304 stainless steel irradiated in a thermal reactor (ETR) at 290°C to a high neutron flu-ence, 6 x loz1 n per sq cm. The analysis of the steel used is given in Table I. The unusual result is that the calculated quantity of helium gas produced by transmutation during the irradiation, 12 ppm, is less than one-tenth the amount of gas necessary to balance the surface tension of the observed cavities produced in the steel during ETR irradiation. Therefore, the cavities would be expected to behave like voids; however, they behave like "gas filled" bubbles. The maximum quantity of helium produced in the steel by B" transmutation was 8 ppm. In addition, the amount of helium formed by (n, (1) fast neutron reactions with the major alloy constituents and nitrogen was calculated to be 4 ppm based on the tabulated differential or effective fission-averaged cross sections of elements in type 304 stainless steel irradiated in typical thermal reactors.&apos;, In previous investigations concerning commercial austenitic stainless steel irradiated in a thermal reactor, the amount of helium gas calculated to be produced by transmutation has always been significantly greater than the amount calculated on the basis that the bubbles were gas filled, PPs= 2y/R. The balance of the gas was assumed to be in bubbles smaller than could be detected on the electron micrographs. Accordingly, the bubbles were attributed to helium produced from transmutation of impurity boron by thermal neutrons. These bubbles were not uniformly dispersed in the matrix but were located principally at grain boundaries, or were radially positioned around a few precipitates located in the matrix and at the grain bundaries., 4 Voids have also been observed in austenitic stainless steel irradiated at high temperature to high neutron fluences in the EBR-I1 and Dounreay Fast Reactors. The voids were uniformly distributed throughout the matrix. The amounts of helium gas produced by transmutation during these irradiations were less than one-tenth the amounts needed to balance the surface tension of the voids formed by the fast reactor irradiation. The fast reactor results are quite analogous to those reported here for the ETR irradiated steel. Electron microscope examination of the fast reactor irradiated material after a 1 hr postirradiation annealing at 900°C disclosed that essentially all the voids had been eliminated. The authors stated that the voids had developed due to the high concentration of vacancies produced during irradiatin., 6, &apos; The microstructure of the ETR irradiated material as-tested at 75O°C, Fig. 1, contained about 2 X lot5 cavities per cm3 with an average diameter of 110A. With the Van der Waals b correction and y = 1500 ergs per cm2, 300 ppm He would balance the surface tension of the observed cavities. Stereoscopic examination of the electron micrographs showed that the cavities were neither preferentially located near the grain boundaries nor highly concentrated at specific regions or precipitates. The cavities were nearly uniformly distributed throughout the matrix, on dislocations and at grain boundaries. These observations imply that the cavities were not the sole results of B&apos;O

Jan 1, 1969

By Donald R. Sadoway

"Molten salt electrolysis is a proven technology for the extraction of metals -- all· the world's primary aluminum is produced in this manner. The unique properties of molten salts also make them excellent media in which to treat a variety of forms of waste. Of special note in this regard is electrolysis in molten oxides, a concept put forward by the author, initially as a ""clean technology"" for producing primary metal. However, in the context of waste treatment, electrolysis in molten oxides is a process offering the prospect of changing the-valence of dissolved heavy metals while making pure oxygen gas as the main by-product. Laboratory tests conducted at a temperature of 1550°C on chromate sludge dissolved in an melt composed of Al2O3, SiO2; CaO, and MgO have confirmed electrochemical production of oxygen on a carbon-free anode. IntroductionMolten salt electrolysis is the electrolytic decomposition of a compound dissolved in an ionic melt. The prime example of this process can be found in the production of aluminum. The compound, alumina (Al2O3)' derived from the mineral bauxite, is dissolved in an ionic melt comprising a multicomponent solution of cryolite (Na3AlF6)' aluminum fluoride (AlF3)' and calcium fluoride (CaF2,). The products of electrolysis are molten aluminum and carbon dioxide, the latter due to the attendant consumption of the carbon anode. Primary aluminum is produced in a reactor known as the Hall cell.' Alternatively, the compound undergoing electrolytic decomposition can be derived from waste. Processing in molten salts, with their capacity to dissolve materials to very high concentrations compared to those attainable in aqueous solutions, can be rather advantageous. High solubilities lead to high limiting current densities, and this, in tum, results in high productivities: For a primer on molten salt electrolysis and a review of the basic literature in the field of molten salts the reader is directed to an earlier publication of the author (1)."

Jan 1, 1996

By Y. S. Sun, P. Gao

"In this investigation, a pilot-scale suspension magnetization roasting reactor was introduced and used to enhance magnetic properties of an iron ore. Consequently, the effects of roasting temperature, reducing gas CO flow rate and fluidizing gas N2 flow rate on the magnetization roasting performance were investigated. The results indicate that the hematite and siderite are almost completely converted into magnetite by a gas mixture of 3.5 Nm3/h CO and 2 Nm3/h N2 at roasting temperature of 520 °C. Under the optimized conditions, the magnetic iron concentrate with an iron grade of 60.18% and iron recovery of 90.17% was achieved. The XRD and Fe mineral phase analyses revealed that most of the hematite and siderite were converted to magnetite, and the magnetic properties were greatly enhanced. INTRODUCTION The steel and iron industry in China has rapidly developed in recent years requiring a large quantity of iron ores. Low-grade and complex iron ores are currently the overwhelmingly dominant mineral resource for iron in China. Therefore, China depends on imported iron ore resources heavily, resulting in an increase in the production costs of iron-making and steel-making[1-3]. Using domestic resources to produce a steady supply of high-quality iron ores is an important step toward the sustainable development of the steel and iron industry[4-5]. The iron ore from Jiuquan iron and steel company is abundant and recognized as typically complex iron ore resources in China. Magnetization roasting followed by low-intensity magnetic separation has been proven as the most feasible methods to upgrade refractory iron ore[6-10]. In present research, an innovative roasting technology, namely suspension magnetization roasting, was developed and applied to recover iron from a typical refractory iron ore. Suspension magnetization roasting technique and equipment developed by Prof. Yuexin Han’s Group at Northeastern University (NEU) is an effective way for the utilization of refractory iron ore. The advent of suspension magnetization roasting will, in China and even globally, produce a significant technological revolution in the field of iron ore beneficiation. Based on the previous works, this paper mainly described experiments on the separation and recovery of iron from a complex refractory iron ore by means of suspension magnetizing roasting and low-intensity magnetic separation processes. The purpose of the research is providing a new technology for effective utilization of refractory iron ore. Process parameters that affected the separation and recovery rate of iron were conducted and optimized, and the reaction process was analyzed by XRD and Fe mineral phase analysis."

Jan 1, 2018

By A. E. Aho

"The Pacific Nickel property lies 7 miles northwest of Hope and 100 miles east of Vancouver, in the Coast Mountains of southwestern British Columbia. Nickel-copper sulphides were discovered in ultrabasic rocks on this property in 1923 and the deposits were explored by Pacific Nickel Mines until 1937, then again between 1951 and 1954 by Pacific Nickel Mines and by Newmont Mining Corporation through its subsidiary,Canadian Ore DepositsWestern Nickel. The property was studied by C. E. Cairnes (1) in 1924, by W. E. Cockfield and J. F. Walker (2) in 1933, by H. C. Horwood (3), (4) in 1936 and 1937, and by the writer in 1951 and 1952. Except for a few thousand tons for trial shipments, the property has never been mined. Indicated ore reserves now total somewhat over one million tons averaging about 1.4 per cent nickel and 0.5 per cent copper, with lesser values in precious metals and cobalt.GEOLOGIC SETTINGThe nickeliferous ultrabasic rocks form part of the core of a 15-milewide block of Late Palæozoic metamorphic rocks and Mesozoic intrusives which extend north-south between the coast batholith of British Columbia and the Chelan batholith of Washington. Margins of this block are faulted in part against less metamorphosed volcanic and sedimentary rocks largely of Jurassic and Lower Cretaceous age (Geo/. Surv., Canada, Map 737 A, 1942). Serpentinites, suggestive of deep transgressive structure, occur within the block, and also at its east margin along faults which are southern extensions of the regional Yalakom-Fraser River fault zone. Some of the other mineral deposits in the Hope area appear to be spatially related to these major faults.The mineralization at Pacific Nickel occurs almost exclusively within a stock-like mass of ultra basic rocks which mingle with, and partly cut, a larger batholithic mass of genetically related diorites and norites of late Mesozoic age (Figure 1 ). The ultra basic mass consists essentially of fresh, medium-grained hornblendic pyroxenite with peridotitic cores and with a remarkable margin of pegmatitic hornblendite. The most hornblendic rocks appear to be chiefly products of reaction and replacement of the pyroxene and olivine rocks. The mineralization consists of disseminated and massive pyrrhotite, with subordinate pentlandite and chalcopyrite, amongst fresh olivine, bronzite, and, Jess commonly, augite and hornblende. Both the ultrabasics and mineralization are cut by small hornblenditic and dioritic dykes, and by veins and alteration zones."

Jan 1, 1949

By Brinton C. Brown

This paper describes the methods and equipment developed at the Bureau&apos;s Experimental Oil-Shale mine near Rifle, Colo., for placing men in position to scale loose rock from the walls, pillars, and roofs of high stopes or rooms. The equipment developed at Rifle has application not only in oil-shale mining but in most of the country&apos;s underground limestone mines and in the exploitation of other mineral deposits mined in high stopes by room-and-pillar methods. Equipment in use at Rifle includes: 1. A boom-type scaling rig with a self-leveling platform constructed on a small "cat"-mounted crane. Men working from the platform on this machine can efficiently scale mine walls and roofs 27 feet above the floor. 2. A conventional fork-lift truck modified to provide a remotely controlled working platform from which men can scale to heights 27 feet above the mine floor. The platform on this unit is larger than on the boom-type rig and allows the men to inspect larger areas of the mine wall from a single setting of the machine. 3. A third rig, consisting essentially of a platform mounted on a tele-scoping tower, designed and built to elevate men 65 feet above the mine floor. Versatility of this machine permits men to work from the platform at heights of 5 to 65 feet. In the operating position, the unit requires a minimum clearance of 25 feet. In the nonoperating position the tower of the machine folds to an over-all height of 15 feet 10 inches to permit travel through haulageways. 4. An industrial gun, lightweight scaling bars, and mechanical scalers, which have been tried for removing loose rock from the mine walls with varying degrees of success.

Jan 1, 1950

By Thomas Barczak

A new generation of hydraulic mine support prestressing devices has been developed. These thin-walled steel shells are machine-welded and can be inflated with water or any liquid to provide prestressing for a wide variety of roof support products ranging from Can supports to props and cable bolts. With an expansion capability of several inches, depending on the geometry and size of the unit, they can also establish roof contact eliminating the need for wooden wedges or crib blocks that are commonly employed with several standing roof support products. Capable of withstanding pressures from 1,000 to 6,000 psi, these cells are able to transfer roof loading into the support structure without rupturing. A recent development has been the addition of an inexpensive yield valve that provides control of the maximum pressure and load development on the support. This paper examines the performance capabilities of these inflatable prestressing units and the impact they have on the performance of various support systems, including an evaluation of the overall stiffness of the support system and the load control during yielding of the prestressing unit. Recommendations are made regarding the design requirements of the prestressing unit to optimize the support performance. A summary of mine applications using this technology is provided with general comments regarding their impact on ground control.

Jan 1, 2004

By S. C. Everett, I. S. Schache, P. A. Bannister, G. F. Balderson

The Pooncarie Project is located in the Murray Basin region of Australia. This region is a potential new mineral sands province. Due to the geological environment and the lithology of the deposit, these deposits have some technical challenges that need to be addressed prior to their successful development. Within the Pooncarie Project the Ginkgo deposit will be developed first. The technical challenges it presents include its geographical isolation, the requirement to remove substantial quantities of overburden as well as the processing issues raised by the highly weathered nature of the ilmenite family of minerals. Ore characterization bench scale testwork and bulk sample pilot plant programmes have been carried out and the data obtained used to design flowsheets for both the wet plant and mineral separation plant circuits with the flexibility to enable these plants to handle the variable heavy mineral assemblage. In addition to the solving of the processing challenges, technical issues such as removal of overburden for the minimum unit cost, the use of hyper saline water in the dredge pond and the provision of infrastructure, have had to be addressed. None the less, the orebodies making up the Pooncarie Project have many positive features including low slimes content, good rutile and zircon grades and the ability to recover most of the ilmenite family of minerals into acceptable TiO2pigment feedstocks. The development of the project is set to proceed with the establishment of mining operations on the Ginkgo orebody feeding a mineral separation plant at Broken Hill. The initial shipment of products is expected to occur in early 2005.

Jan 1, 2003

By Frederic Benard

THIS paper constitutes a preliminary report on experimental work done to date on the anode-furnace treatment of blister copper containing relatively high percentages of nickel. The investigation has not been completed but results obtained to date are considered of sufficient interest to warrant publication. Blister copper treated by the Ontario Refining Co. originates from the Copper Cliff smelter of The International Nickel Company of Canada, of which the former is a wholly-owned subsidiary. The blister as received contains from 0.50 to 1.50 per cent Ni, and in this respect differs from that treated by other refineries on this continent. During the anode-furnace treatment, only a portion of the nickel content is removed, and of the amount remaining in the anodes a varying percentage is found in the anode slimes. This necessitates a more extensive treatment than ordi-nary, nickel-free material. Sometimes it is necessary to repeat roasting and leaching operations several times before the nickel content is low enough to permit the slimes to proceed to the doré furnace. This, besides increasing treatment charges, causes greater selenium stack losses and involves a longer tie-up of precious-metal values. Therefore this investi-gation was undertaken with the aim of determining the factors influencing the diversion of nickel into the anode sludge. From experience it was known that by keeping the nickel content of anodes at 0.55 to 0.60 per cent maximum a relatively satisfactory slime resulted. One avenue of attack therefore was developing improved elimination in the anode-furnace treatment so that the anode content mentioned above was not exceeded. Another angle was to improve the solubility, during electrolysis, of the nickel constituent in the anodes, thus decreasing the percentage diverted to slimes. It may he mentioned here that nickel dissolving electrochemically and entering the electolyte pre-sents no difficulty from a treatment standpoint. Both of these approaches were studied and are discussed sepa-rately below.

Jan 1, 1938

The election of the following officers of the Council for the fiscal year 1919-1920, was confirmed by the Council on June 12th, 1919. President, S. E. Doane; vice-president, Wm. J. Clark; general secretary, Clarence L. Law; treasurer, L. B. Marks; directors, E. C. Crittenden, F. E. Cady, R. B. Ely. The membership of the Council for 1919-1920 will therefore be as follows: S. E. Doane, G. H. Stickney, George A. Hoadley, Wm. J. Clark, H. A. Horror, Otis L. Johnson, H. K. Morrison, Clarence L. Law, L. B. Marks, Adolph Hertz, S. C. Roger, P. S. Young, John C. D. Clark, Evan J. Edwards, James J. Kirk, E. C. Crittenden, F. E. Cady, R. B. Ely.

Jan 7, 1919