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By Corby G. Anderson, Sheikh Abdul Rezan Sheikh Abdul Hamid, Sanjith Udayakumar, Ahmad Fauzi Mohd Noor, Teuku Andika Rama Putra

Chemical and mineralogical characterization of Malaysian monazite, a phosphate mineral, bearing rare earth elements separated from the tin tailings originated from Ipoh, Perak, Malaysia, was performed in this paper. The study aims to collect detailed information on the chemical composition, crystal phases, and microstructure of the mineral monazite concentrate that would aid to optimize the subsequent hydrometallurgical processes for high-efficient separation of thorium and other associated rare earth elements. A systematic characterization study of the concentrate was conducted using techniques such as optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). These techniques analyzed the morphological details on the surface, elemental analysis, and mineral association assessment and identified the surface functionalization groups. The bulk composition and the mineral phases in which the elements are present were studied by wavelength-dispersive X-ray fluorescence (WD-XRF) and X-ray diffraction (XRD) studies respectively. The XRF analysis confirmed the presence of Ce, La, Nd, Pr, and Y (rare earth oxides: REO’s ~ 60 wt.%) while thorium dioxide (ThO2) accounted for 7 wt.% of the total composition. Traces of Ca, K, Al, Fe, Ti, and Mn were also confirmed by SEM elemental mapping. The XRD results confirmed that the concentrate was primarily composed of monazite (Ce, La, Nd, Th (PO4)) along with minor impurity phases of quartz. Automated mineralogical analysis was used as a confirmatory tool to corroborate the preliminary evidences. Based on the particle size distribution analysis supported by SEM, the majority of monazite grains were found to be present in the size range of 170–210 μm. Strong bands of PO4 and SiO4 were observed in the IR spectra corresponding to the phospho-silicate matrix of the REE mineral.

By Corby G. Anderson, Sheikh Abdul Rezan Sheikh Abdul Hamid, Sanjith Udayakumar, Ahmad Fauzi Mohd Noor, Teuku Andika Rama Putra

Chemical and mineralogical characterization of Malaysian monazite, a phosphate mineral, bearing rare earth elements separated from the tin tailings originated from Ipoh, Perak, Malaysia, was performed in this paper. The study aims to collect detailed information on the chemical composition, crystal phases, and microstructure of the mineral monazite concentrate that would aid to optimize the subsequent hydrometallurgical processes for high-efficient separation of thorium and other associated rare earth elements. A systematic characterization study of the concentrate was conducted using techniques such as optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR). These techniques analyzed the morphological details on the surface, elemental analysis, and mineral association assessment and identified the surface functionalization groups. The bulk composition and the mineral phases in which the elements are present were studied by wavelength-dispersive X-ray fluorescence (WD-XRF) and X-ray diffraction (XRD) studies respectively. The XRF analysis confirmed the presence of Ce, La, Nd, Pr, and Y (rare earth oxides: REO’s ~ 60 wt.%) while thorium dioxide (ThO2) accounted for 7 wt.% of the total composition. Traces of Ca, K, Al, Fe, Ti, and Mn were also confirmed by SEM elemental mapping. The XRD results confirmed that the concentrate was primarily composed of monazite (Ce, La, Nd, Th (PO4)) along with minor impurity phases of quartz. Automated mineralogical analysis was used as a confirmatory tool to corroborate the preliminary evidences. Based on the particle size distribution analysis supported by SEM, the majority of monazite grains were found to be present in the size range of 170–210 μm. Strong bands of PO4 and SiO4 were observed in the IR spectra corresponding to the phospho-silicate matrix of the REE mineral.

By L. Larson

Rock samples were taken, away from zones of mineralization , from seven sections of five rhyolitic zones as define d by Spence (l967) in the Noranda area. The purpose of the investigation was to test whether there were intrinsic differences between the zones which would differentiate between non-productive zones and productive zones. For the elements sought (major elements, Cu , Pb , Zn and S) , no clear chemical difference between the zones was found. Thus, identification of a favour able zone from the over -all composition of the zone does not appear promising. Within sampled sections, there is no clear gradual compositional change up through the sections. A capping of highly siliceous massive rhyolite is present in five of the sections sampled. A layer of relatively basic material occurs near the base of individual units. The third (mine zone) and later zones contain abundant pyroclastic material, where as the non-productive zones do not.

Jan 1, 1977

By E Matinde, M. Mnisi, I. C. Thobadi, W. Clark, J. D. Steenkamp

Pyrometallurgical smelters utilise tap-holes, through which liquid metal, matte and/or slag are tapped at regular intervals. However, tap-hole failures can have a devastating impact on smelters, which includes loss of equipment, human life and business interruptions. Contributing factors to tap-hole failures include poor and/or incorrect refractory material selection, including tap-hole clays. The functions of tap-hole clays in smelters include their ability to be extruded and drilled with ease at the end and beginning of a tap, and their ability to resist chemical wear due to molten metal and slag during tapping. Mintek is currently developing methods of evaluating properties of tap-hole clays with a specific focus on workability, and wear mechanisms of clays due to ferrochrome alloy and slag. Of particular interest to this study was the characterisation of various tap-hole clays. This paper evaluates the chemical and phase chemical properties of three different tap-hole clays. The bulk chemical composition of the tap-hole clays was determined by inductively coupled plasma optical emission spectroscopy, proximate analyses and combustion methods. The bulk phase compositions and specific phase chemical compositions were studied using quantitative X-ray diffraction, scanning electron microscope and electron probe microanalyses techniques. Keywords: Tap-hole clay, chemical analyses, phase chemical analyses, ferrochrome

Jan 1, 2020

By J. Hop, A. Støre, T. Foosnæs

The carbon cathode for aluminium electrolysis is also part of the container of the process. In order to understand the behaviour and possible failure of the cathode, detailed material properties under operating conditions are needed. The paper reports experimental studies of bath and sodium in filtration, graphitization with time, loss of strength due to sodium, sodium expansion as function of pressure, as well as creep due to the developed stresses. As an example, sodium and thermal expansion data are used to calculate strain-stress models of realistic cell designs, and possible design weakness can be pointed out. Keywords: carbon, cathodes, sodium expansion, strength, graphitization, creep

Jan 1, 2004

By White L. R, Boger D. V

The paper describes the surface chemistry and particle physics that control the fundamental flow properties (Theology) of mineral particle slurries. We further address, through a series of case studies, the design data that emerges from experimental studies of the flow properties of complex, high volume fraction mineral slurries. The case studies are drawn from mineral oxide concentrate processes, tailings dewatering operations and from filter cake production and management. The paper emphasises the essential links between design of process slurry handling systems and the control of the flow of such slurries by control of the pulp chemistry.

Jan 1, 1992

By James Rowland, Isaac Zlochower, Richard Mainiero, Michael Sapko

The National Institute for Occupational Safety and Health (NIOSH) carried out exploratory laboratoryscale studies to identify factors that may contribute to nitrogen oxides (NOx) production associated with non-ideal detonation of blasting agents. Explosive admixture with drill cuttings, loss of fuel oil in ammonium nitrate and fuel oil (ANFO) from wicking, ammonium nitrate dissolution with water, degree of explosive confinement, ANFO density, and critical diameter were identified as contributing factors to increased NOx production under the laboratory test conditions. Experiments were also conducted to examine the effectiveness of various additives in reducing the NOx production from ANFO, emulsion, and ANFO/emulsion blends. Aluminum powder, coal dust, urea, and excess fuel oil in ANFO formulations were tested and were found to reduce both the nitric oxide (NO) and nitrogen dioxide (NO2) production. Fumes measurements were obtained in the NIOSH underground closed chamber from the detonation of 4.5-kg (10 lbs) charges in schedule 80 seamless steel pipe and from detonations in light weight galvanized steel stove pipe. Some exploratory tests were also conducted with 0.8-kg (1.8 lbs) charges of pulverized ANFO initiated with 0.08-kg (0.18 lbs), 50/50 (Pentolite) boosters (in the NIOSH 12-ft (3.7-m) diameter steel sphere) to measure the degree of fumes production associated with post-detonation oxidation. Ammonium nitrate, emulsion and Pentolite boosters were also detonated in an oxygen-poor environment.

Jan 1, 2002

By T. H. Eyde

Several hundred natural zeolite deposits occur in Tertiary and Cretaceous age formations of the western United States. Most of the large deposits are altered vitroclastic tuffs. Many of these deposits consist of a matrix of a high purity zeolite mineral or minerals in which fragments of unaltered rock are imbedded. These deposits represent an extensive resource of zeolite minerals which can be beneficiated to a consistently uniform, high quality product. The beneficiated natural zeolite products will possess many advantages over the selectively mined, unbeneficiated natural products currently being produced. These advantages will include: uniform particle size, high purity, consistent quality, high brightness, low iron content, high attrition resistence, uniform cation exchange and adsorption capacities, and low price.

Jan 1, 1981

By L. R. Hossner

Chemical and physical properties of surface soils and overburden materials must be evaluated prior to strip mining activities. This information can be used to assess whether subsurface overburden can be equal in quality to the existing surface soils, especially when these soils are classed as prime farm lands. In Texas, materials from the Carrizo, Calvert Bluff, Simsboro, and Hooper Formations overlie the lignite. The Carrizo Formation consists of thick clean sands with poor water and nutrient retention capabilities. These materials are least suited for placement of the surface of reclaimed land. The oxidized, medium textured overburden from the Calvert Bluff and Simsboro Formations possess adequate water and nutrient properties and are better suited for sustained plant growth. Non-oxidized Calvert Bluff and Hooper sediments generally have acceptable properties for reclamation. However, caution must be exercised in vegetating these materials since they may contain acid forming sulfide minerals.

Jan 1, 1982

By Carter NB

A statistically-designed experimental program has been used to study compositional and processing variables which influence the development of strength and reducibility of iron ore pellets. The effects of chemical composition and processing variables were investigated by indurating laboratory-made green pellets, of known composition, under approximately isothermal conditions in a pot- grate simulator. Some findings from a six- variable study are summarized in the form of contour diagrams and emphasize the importance of interactions between the variables. Production of strong, highly reducible pellets is possible over a considerable range of combinations of temperature and firing time. Abrasion index (AI) and cold compression strength (CCS) improve as both these variables increase, but reducibility (R) declines, so a compromise is required. When the lime level is too low to form enough slag for bonding, the AI and CCS may be inadequate. Larger additions of lime tend to improve AI and CCS, with only slight effects on R. Finer grinding of the balling feed (i.e. higher Blaine index) tends to improve Al and CCS without

Jan 1, 1980

By T. P. Lim, A. J. Vivyurka, N. K. Davé

Chemical and radioisotope stratification studies were carried out in an abandoned uranium tailings pile at Elliot Lake, Ontario, Canada. The tailings, with an average thickness of 7 m over an area of 16 hectares, were deposited approximately 20 years ago on a layer of black peaty material which overlays deposits of permeable glaciofluvial sands. Geohydro-chemical investigations of this tailings area have been ongoing since 1978. The radioisotope profile study was conducted on three adjacent sites. Solid core samples, collected with a split spoon sampler at various depths, were analyzed for various chemical and radioisotope constituents. The results indicated by 2 distinct zones of stratification; an upper zone, where the constituents were uniformly distributed, and a lower zone, near the peat-tailing interface, which showed increasing concentration with depth. Within the peat layer, the concentration decreased rapidly with no significant levels of contaminant penetration below the peat layers observed, though the samples were limited. The pH profile showed that the top 5 m of the tailings have been oxidized, the average soil pH in this zone was 3.4 compared to 5 .8 underneath it. The groundwater hydrology of the system was observed to be complex showing downward and lateral flow in the dry season and lateral and upward flow during the spring and periods of heavy rainfall. The results are discussed in terms of a model based on the combined segregation and settling process of the tailings fine fraction, and the geohydro-chemical interaction of the solid and liquid phases.

Jan 1, 1981

The Witwatersrand reefs provide excellent examples of chemical and structural control on gold distribution. All mined gold appears to coma from a carbon -gold association and/or Fe-S-Au association, and also from immediately above or below unconformity surfaces. A total raliance on the current syngenetic model for Witwatersrand gold does not appear to be justified from the accumulated data and may be responsible for missed opportunities during exploration: consideration of other models is suggested especially where they better fit the data. The stratabound natura of Witwatersrand gold 1& critical to mining, but is emphasized in syngenetic models to the virtual exclusion of many other important observations. By analogy with other deposit types, stratabound character is probably a poor guide to genesis.

Jan 1, 1988

Upon subduction, water is liberated from the sediments and the porous struc- ture of the oceanic crust and from de- hydration of minerals for redistribution and chemical reaction. A survey of pro- cesses which are likely to occur along the subducting plate reveals that water may well be basic in subduction induced gas generation, magma formation and ore deposition. In analogy to the industrial water gas process, reaction of water with car- bonaceous matter, in subducted sediments is likely to yield substantial volumes of hydrogen and carbon dioxide. While water and carbon dioxide appear to play a determining role in the development of differentiated magmas, hydrogen will react with metal sulfides and sulfur to form hydrogen sulfide which is essential in sulfide ore depo- sition. A survey of possible metal extrac- tion chemistry along subduction suggests a stepwise solubilization of metals from sediments and oceanic crust, and a poten tial accumulation of dissolved metals in zones of characteristic composition. The metal spectrum in ore deposits at near surface appears to reflect the com- position of the solution in the respec- tive subduction zone. A tendency for preferential solubi- lization of copper at subductidn level, from among the transition metals, an in- creasing generation of hydrogen sulfide in the sane direction and partition effects as well as sulfide precipitation characteristics lead to enrichment in copper and to its selective deposition in the direction towards the trench as observed in S. Latin America. A postscript deals with the formation of native copper.

Jan 1, 1986

Sustainable development is a critical discussion topic in the mining industry today. The topic is necessarily broad and complex, covering an entire spectrum of related areas, from geology to end-use products. The objective of this keynote address is to focus on the chemicals and chemistry aspects - especially research and technology transfer - in sustainable mineral processing. Chemicals came to play a critical role in mineral processing during the last century, and they will play an equally vital role in confronting the sustainability challenges of the 21st century, particularly in the areas of greener chemicals, water efficiency and water resource management; waste reduction and remediation; minimising environmental impact, safety and health risks (meeting and exceeding the requirements of regulations); energy efficiency; and converting mineral resources into reserves. This keynote address argues that the current research framework is no longer adequate to serve the goals of sustainable mineral processing. The problems studied are often too narrowly defined or irrelevant, while the research efforts are fragmented and the methods and approach employed are often too reductionistic to produce useful knowledge. A new framework for research is needed. This address further argues that a new framework based on a holistic or systems approach can best tackle the challenges of sustainable mineral processing. Central tenets of this approach include a recognition that, in complex systems, the behaviour of the whole system is more than the sum of the individual contributions, and that interactions occur in real time, often in subtle and complex ways. The focus is thus on the behaviour of the whole system. Indeed, a comprehensive understanding of the system through large-scale measurements should precede a study of parts or of idealised models of the complex system. The result will be a sound knowledgebase, better solutions to the challenges of sustainable development, and improved technology transfer. Developing such a framework will pose a formidable challenge, requiring significant time and effort as well as a confluence of diverse specialties and strategic collaboration. Fortunately, recent developments in the context of reagent optimisation provide us with a prototype of a holistic approach. We can also draw upon methodological innovations in the biological sciences, where the critical need for a systems approach is well recognised and significant advances have been made.

Sep 13, 2010

By Daniel C. McLean

Chemistry plays a more important role in milling operations than is generally recognized, particularly in fluid- solid separation processes. Chemical aspects are also very important insofar as plant water quality is concerned, and in the manner in which this water quality effects plant design and operation. Aside from the inherent chemical characteristics of plant water, the mineral preparation industry is becoming increasingly more dependent on the use of mining chemical reagents--relatively new to the coal industry, but items of I standard usage in complex metal recovery plants. These chemicals have many useful properties and can produce significant improvements in operations and metallurgical efficiencies when used properly and intelligently. They can produce poor results and sometimes severe losses when used improperly. Most reagents are relatively expensive on a per pound basis, hence costs can be excessive if they are used wastefully or inefficiently.

Jan 1, 1968

By Terence Makanyire, Animesh Jha

The dissolution and chemical properties of vanadium, zirconium, and niobium in rutile lattice are analyzed by comparing the octahedral site preference energies, with respect to Ti4+ ion in the solvent phase. The oxides are often present in rutile lattice and interfere in achieving the quality of pigment grade TiO2 due to favourable Gibbs energy for dissolution in the solvent rutile matrix. Binary mixtures of V2O5 { TiO2; Nb2O5 { TiO2 and ZrO2 { TiO2 with compositions of 80, 85, 90, 95 and 97 wt% TiO2 were made, pelletized and sintered at 1100 °C for 24 hours. The solidsolution mixtures were then cooled and leached in 2M NaOH for 3 hours at 60 °C. Phase and lattice parameter characterizations, and microstructural and compositional analyses were then carried out using X-ray diraction and SEM/EDX, respectively. The leachates were analysed by Atomic Absorption Spectroscopy (AAS), using which the solute dissolution model for oxides were investigated.

Jan 1, 2014

By Mishark Nnabuchi

A heterojunction of PbS - CuS thin film has been grown on glass slides by SGT. The films were annealed for 1hr at temperature of 373K and 423K respectively. The optical properties were characterized using a UNICO UV - 2102 PC Spectrophotometer at normal incidence of light in the wavelength range of 200 - 1000nm. The minimum percentage transmittance was observed to be 34% for sample A and 25% for sample B within the same optical region. The band gap energy was determined from the spectra to be 2.05eV for sample A and 1.85eV for sample B which gave a band shift of 0.20eV. It can thus be concluded that the optical properties of the films within the VIS - UV - NIR can find application in solar thermal technology, particularly as antireflection coating, window materials and as good materials for selective solar cell fabrication.

Jan 1, 2010

By S. A. Moffatt, S. K. Kawatra, T. C. Eisele

This paper describes the decomposition of bulk samples to fine particles using alkali metal vapors. Basalt, pyrite, alumina, pyrex and quartz glass samples were exposed to sodium vapors at elevated temperatures for different time periods up to 30 hours. Examination of the particles showed that fragmentation occurred preferentially along grain boundaries. Emphasis of this paper is on the theory of the degradation mechanism and the size distribution of the particles produced.

Jan 1, 1992

By S. K. Kawatra

Many mineral oxide and multi-component oxide (basalt) specimens break down into powders upon expo-sure to sodium vapor at elevated temperatures for extended times. This paper examines several possible mechanisms of oxide breakage by sodium vapor, both experimentally and from a thermodynamic viewpoint. The oxides for which reduction by sodium was thermo-dynamically favorable all exhibited some degree of fragmentation. The oxides which were not favorable for reduction by sodium did not exhibit fragmentation, with the exception of rutile, a titanium oxide. The rutile fragmentation was caused by the reduction of iron that was in solid solution in the rutile crystal structure.

Jan 1, 1995

By John A. Cherry

Groundwater monitoring conducted at an acidic uranium-tailings impoundment in Wyoming and at one in Ontario indicate that at these unlined impoundments situated on unconfined sand aquifers, there exist well-developed plumes of contaminated groundwater. In the literature similar results are reported for three other unconfined aquifers at mill sites in Wyoming. The plumes extend for distances of several hundred to a few thousand metres from the impoundments. They have a zone of low pH beneath and adjacent to the impoundments and a larger zone of near-neutral pH that extends to the outer limits of the plume. The low-pH zones are generally small compared to the neutral-pH zones because the advance rate of the fronts of acidic tailings-derived water is slower than the average velocity of groundwater which controls the advance of the high pH zone. The retardation of the acid fronts is a result of geochemical reactions that cause hydrogen-ion consumption in a slowly-advancing neutralization zone. Within each of the plumes, the low-pH zone has high concentrations of transition metals, heavy metals and radionuclides. In the neutral-pH zones all of the metals and radionuclides occur at significantly lower concentrations and are generally at levels much below those specified in national drinking water standards. An exception at two of the Wyoming sites is uranium, which exists at levels close to the drinking water limit. A second exception is ferrous iron at the Ontario site, which occurs at high concentrations throughout most of the plume. The carbonate alkalinity at this site is much lower than at the Wyoming sites. The field data indicate that even in very permeable aquifers with a low content of silt and clay, there is normally a considerable capacity for acid-front retardation. To take advantage of this capacity to control contaminant movement in the design, operation and decommissioning of tailings impoundments, it is necessary to be able to predict the rate of acid-front movement. This predictive task has two primary components. The first is to identify the important flow paths from the tailings through the groundwater system and the second is to determine the degree of acid-front retardation that will occur as the tailings-derived water moves along these flow paths. Relative to these two tasks determination of the effects of hydrodynamic dispersion is generally of lesser importance and simple approximations that do not involve field or laboratory tests are probably adequate. In order to effectively apply the acid neutralization concept to the prediction of subsurface contaminant migration at uranium-mill tailings, improved representations of hydrogeochemical behavior of iron and aluminum in the neutralization zone and of the consumption of hydrogen ions through reactions with carbonate and aluminum-silicate minerals are required. Along with the hydrogen ions contained in the tailings water the ferrous iron represents a large potential source of acid but the extent to which ferrous iron converts to ferric iron to produce acid is problematic. Detailed hydrogeochemical evaluation of existing contaminant plumes and the performance of laboratory experiments under appropriate redox conditions ore prerequisites for the improvement of predictive models. However, the existing field and laboratory data provide a basis for preliminary predictions of contaminant migration from acidic uranium tailings impoundments.

Jan 1, 1982