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By L. Simpson

South African is a repository of significant deposits of a variety of minerals. The Citigroup confirms this assertion with an estimate of in-situ valuation of US$2.5 Trillion. The mining sector plays an important role in the South African economy. In addition to the mineral resource base South Africa has other comparative advantages. Firstly, South Africa retains major mining companies that participate globally, including Anglo American, Goldfields and De Beers. Their global involvement offers much to the local mining sector and the broader economy. Secondly, government established research councils. The Council for Geoscience (CGS) was established to manage the Geological Survey of South Africa, including the reduction of geo-scientific investment risk. The Council for Scientific and Industrial Research (CSIR) promotes industrial development, including mining technology development. Mintek undertakes mineral research from mineral examination of ores, to extraction and refining technologies and manufacture of end products. Thirdly, South African universities teach and conduct research along the mineral value chain. They have increased their minerals graduates? capacity, thus advancing knowledge and skills. Knowledge and technical progress are behind productivity growth and emergence of competitive advantage. The research and development (R&D) capabilities of industry, science councils and universities, working in unison, will enhance the competitiveness of the South African mining industry. The National System of Innovation (NSI) requires multi-disciplinary, collaborative research. Key R&D elements, including skills and expertise, funding and facilities, must be available to implement a long-term national strategy or programme. Improved international collaboration and partnerships between government, academia and industry driven human resource development (HRD), ultimately develop the critical mass for inter-generational skills requirements. This trend requires an expansion of research collaboration programmes. Decisions involving investments and collaborative actions pertaining to R&D in the sector necessitate an analysis of the South African mineral value chain R&D capability. This paper analyses the evolution of R&D capability from exploration to refining, tertiary education, science councils and industry. The political economy of the evolution of this capability is analyzed in relation to the central role that the South African government plays in creating an appropriate supporting environment and related initiatives to enhance R&D and innovation. Keywords: research and development (R&D), science councils, universities, industry, innovation policy, South Africa

Sep 1, 2012

By Jury P. Nazarov

"At present the traditional study of crystal lattices of nmerials in a topic “flota tion mineralogy ” is used up. The present investigation is development of the a sclsical approaches to t he analy sis of ideal crystal lattices and f ormation on the basic obtained results of consultation, having practical chara cter.The strategy of develop ment floatation reagents i s offered, which basic pr inciple – complementary assembling m olecules forming surface co mpounds so thatth e steric charact eristic of the “visitor "" (of a polar gro up of molecule SAS) corresponded to the st er ic requirements of the ""o wner"" (elementary cell of a mineral), or coincided inter molecular cavities). In itsh case process of for mation of surface com pounds ca n be considered(a first approximation) as a realization of a principle of the design er "" LEGO "".The approach, which basic idea consi deration actioonf reactant ions and ions of ele mentary cell as three-di mensional objects is developed. And at suchp paroach the laws of a ster eometry - laws describin g spatial effect s are applicable. Thus it is possible toconsider a miner al surface as a mat r ix - basis for formation of the requirem ents to polar group of a molleec cuollector, and or (it is possible) depressant. As a whole approach represents a generalized principle double com plementation, enveloping both power, and geometric asp ects (concept ""lock "" and “key "" - spatial conform ity. Figure 7 (left). Fragment of a crystal lat tice of ap atite. Oleic acid ions interact on ly with th e calcium cations locate d on a long axi s of an elementary c ell. Magenta colour represe nts the calciu m cations, which are n ot particip atin g in interactio n, as th e degree of screening by ions neighbours exceeds 1.Figure 2. (right)The illustration of space complementary. “Afterbuilding” an elementary cell of apatite (radical PO4) related molecules of the visitor – alkyl phosphate (polar group PO4). Cations of calcium are not shown."

Jan 1, 2003

By M. Bhartia

India is the 5th largest producer of steel in the world and is slated to produce more than 180 Mt by 2020. Expectedly about 50 % of this would be through the Blast furnace route and the rest through Sponge iron / DRI route. Considering that there will not be any major change in iron making technology by that time, the Blast operation would require lump ore (10-40mm) with around 64% Fe grade and sinter fines (<10mm) with 60% Fe (min) as its feed. DRI process would need calibrated ore of size 5-18 mm as the most suitable size of feed. It is also expected that of the total requirement of ore for the DRI route a significant part would be DRI pellets. In India, there is considerable debate going on regarding the technology to be adopted for the processing of iron ore and there is a lack of clear consensus. The above scenario indicates that the processing requirement of iron ore in the country would involve both washing technology as well as beneficiation technology. CDE Asia Ltd is in the forefront of iron ore processing in the country and the experience gained by the company over the last few years of functioning has led the company to believe that route to be adopted depends on the end product requirement and the starting grade of the feed. Keeping in mind the nature of the feed required for the Blast furnace & DRI operation; it is obvious that good washing technology would be highly beneficial to the iron ore industry. Depending on the grade of ore available the limits of washing will be decided and equipment for lump ore beneficiation such as jigs could be incorporated into the washing circuit. Scrubbing of ore either before washing or selectively scrubbing the lumps could be necessary. Very low grade ore and jig rejects would be required to be totally ground and beneficiated for the production of pellet feed in order to utilize the iron ore resources entirely. Another source of ore for pelletisation would be slimes generated from the washing process as well as the huge quantities already available in the tailings dams in the operating mines. Deslimimg and magnetic route of beneficiation could release at 30-40% of the Fe locked up in these tailings ponds/dams. The paper describes the concept with examples from operating plants and proposes how the adoption could be engineered through test work and proper plan of integration. Keywords: washing, beneficiation, iron ore, lumps, sinter fines, pellets, jigs, screens, evowash, nanowash, thickeners, log washers, drum scrubbers

Sep 1, 2012

By Volker Vogt, Wolfgang Sand, Eberhard Gock

"For about 20 years, the use of bacteria to control the flotation process for the production of raw material concentrates has been the subject of worldwide scientific and engineering efforts. The objective is to reduce the consumption of biologically non-degradable toxic reagents. The principle idea is to use the activity of bacteria in natural leaching processes – known since the middle of the last century – for controlling flotation processes.It was discovered that the selective activity of bacteria during the extraction of raw material concentrates by means of flotation could also be achieved with extracellular polymeric substances (EPS), excreted by bacteria. EPS, which is extracted by means of centrifuging bacterial cultures, can help to significantly reduce the use of cyanides, approximately 200,000 t/a are used for ore dressing today.The bacterium used was Acidithiobacillus ferrooxidans. In order to identify the bandwidth of the oxidation activity, 21 bacterial strains of the strain collection of the University of Hamburg were attracted to iron(II) sulfate and pyrite under defined conditions. All strains oxidized iron(II) sulfate ten times faster than pyrite.EPS has so far been derived from four strains. In general, EPS extracts are divided into a hydrophilic and a hydrophobic fraction. The hydrophilic fraction is composed of e.g. fucose, rhamnose and glucose; fatty acids such as dodecanoic acid, hexadecanoic acid, octadecanoic acid and nonadecanoic acid were found in the hydrophobic fraction. Pure mineral phases and mineral mixtures were used for the flotation tests. The outcome was reproducible results with technical flotation machines. The research results known so far are mainly based on investigations with micro flotation devices, which are usually used for the characterization of reagents and which do not allow a direct translation to the technical scale."

Jan 1, 2003

By Montaser S. EL Salmawy, Takahide Wakamatsu, Eishi Kusaka

"In conventional flotation, fluoride ions selectively would react with the aluminum site on the microcline surface and produce negative charged sites for amine to be adsorbed (Smith, 1976). According to this view, aluminum site is considered as a key feature in feldspar flotation. Generally, fluoride ion has been widely used as a modifying agent in silicate flotation. Since O'Meara's patent appeared on HF -amine reagent system to selectively float feldspar from quartz in 1942, relatively few contributions have been devoted in this issue. The reason might be that the process works very well, and accordingly there is no initiative to investigate in this area. However, due to the awareness of international community to restrict using of hazardous reagents like HF, sound engineering practice to search for alternative methods, not utilizing HF, has been launched. Inspection of literature, one can find several works dealing with this issue.In this contribution, the effect of ethoxylation of long chain alcohols on the quartz and feldspar flotation behaviors was investigated for surfactants of the octylphenol polyoxyethylene family. The tests were carried out with an average of 7.5 (Triton X 114), 9.5 (Triton X 100), 30 (Triton X305), 40 (Triton X 405) and 70 (TritonX 705) oxyethylene units. Electrokinetic and flotation studies on quartz have shown that at low pH values, quartz could be floated with polyoxyethylene octytlphenols. The possible mode of adsorption of these nonionic surfactants may be suggested to be due to hydrogen bonding between the oxygen of ether and hydrogen in the free hydroxyl groups on quartz surface. It was anticipated that the selectivity between quartz and microcline would decrease as oxyethylenic chain length increases."

Jan 1, 2003

By D. R. Nagaraj

The traditional (popular) approach to reagent development and optimization, which has become entrenched in both research and practice for many decades, is highly reductionistic, incremental and costly, does not produce robust chemical solutions, and is not sustainable. There are also several other key drivers and changes in the mineral industry that clearly warrant a new approach. In response to these, an intense effort was made at Cytec over the past fifteen years to develop a meaningful, efficient, and sustainable approach to develop new reagents and robust chemical solutions in mineral separations. This effort culminated in three important outcomes: a) development of the holistic approach, called FLOTATION MATRIX 100? process, b) novel reagents, and c) enhanced application knowledge for reagents. In this paper, the efficiency, utility and power of the holistic approach will be demonstrated with examples using both existing and new reagents in the processing of Cu-Au, Au and Cu-Mo ores.

Jan 1, 2014

By Jannie van Deventer

"Innovation in the minerals industry has been lagging behind comparable industries like oil and gas. An incremental innovation culture that tolerates long lead times between invention and adoption has been exacerbated by a research grant structure that inhibits radical idea generation. Entrepreneurs who can make the link between ore source, technology and finance will cause a shift in innovation culture and open up substantial opportunities in the minerals industry of the future. By extrapolating existing trends in technology within and outside mineral processing, a crystal ball vision of future innovation is shaped with the aim to lower energy and water demand, reduce CO2 emissions, decrease operating and capital costs, reduce environmental impact, and secure a social licence to operate. Advances in nanotechnology, advanced materials and biotechnology will impact mineral processing, but the initiative for technology transfer must come from mineral processors. Laminates of graphene oxide can offer efficient filtration and separation media, while microfluidic devices will be used for desalination, solvent extraction and analysis. Substantial progress is expected on benign lixiviants and separation agents, such as nanoscale supramolecular hosts that can serve as high-capacity, selective and recyclable ligands and sorbents, and solid aminobiphosphonate-based adsorbents. Radical ideas for the recovery of precious metals from non-assayable ores and the generation of energy above unity will be adopted in selected minerals projects. In-situ mining in which microbes generate lixiviants at mineral surfaces will simplify processing circuits. Specific ores will be subjected to microwave processing and electropulse liberation to enhance recovery. Ultrafine grinding using devices of low energy consumption will be done mainly dry, followed by dry separation. New flotation cells will remove efficiently either coarse particles or ultra-fine particles, with mineral surfaces being modified not just by new reagents but also by selective microbes. Innovation in mineral processing indeed has a bright future."

Jan 1, 2014

By O. Güven

In recent years, there is an increasing demand on manganese consumption which stems from the important role of manganese in carbon steel production. And the growing need for manganese ores makes the beneficiation of low-grade manganese ores more economical. In this study, the characterization and beneficiation studies were carried out to propose a flow sheet for typical low-grade Turkish manganese ores. For this aim, different gravity separation methods were applied. According to the mineralogical analysis, the major mineral phases are pyrolusite (MnO2) and psilomelane (MnO2) while the major gangue mineral is radiolarite. Gravity separation tests were accomplished by using jigs, shaking table, MGS (Multi Gravity Separator) and in order to obtain products with high Mn ratio, high intensity magnetic separation was also performed. As a result, different combinations of flow sheets were utilized and a concentrate assaying 56.5% Mn with 85 % recovery was obtained.

Sep 1, 2012

By Carsten Gerold

The paper is giving an overview about successful operating Loesche Vertical ? Roller ? Mills (VRM) installations and summarises the main benefits of the dry compressive Loesche grinding technologies in Airflow- and Overflow-Mode. Some of these benefits are optimised energy efficiency of the grinding - classifying - circuits, increased mineral recoveries and decreased OPEX costs, at a parallel simplification of the process route. Within this paper the process values of the Loesche VRM are compared to existing or planned conventional grinding ? classifying circuits. Further advantages discovered in pilot trials and examples for new more efficient process route alternatives are given. The paper reports about production and pilot trial experiences obtained by crushing and grinding Iron Ore, Iron Ore Concentrates, Copper Shale, Copper Matte, Copper Slag, Titanium Slag, Tin Slag, Steel and Stainless Steel Slag with Loesche VRM.

Sep 1, 2012

By Nicholas Enraght – Moony, Alvin Johns, Zhonghan Zhang, Zhang Xianhua, T. Choo

"The tungsten (WO3)-rich ores from King Island Scheelite (KIS) Mine, Australia, containing scheelite(CaWO4) were previously recovered by gravity separation and flotation of fine scheelite (1978-92) with an overall recovery of 76% when both circuits were operating. Recently extensive test work has been conducted both in China and in Australia on KIS ores, assaying from 0.50%-1.34%WO3, and tailings assaying 0.2%WO3(GZRINM 2009; 2011a; 2011b). A new approach, which aimed at improving both recovery and grade of concentrate by means of an innovative all flotation route WOF (Whole Ore Flotation), achieved excellent results: 90%-92% recovery to concentrate grade of 66%-70%WO3for the ores. The process is characterized by the use of selective reagents in flotation, including a newly developed collector for scheelite, GYWA. The WOF process also embraces the "Improved Petrov Method" in the cleaning of scheelite rougher concentrate. Earlier investigations found that the removal of sulfides by flotation prior to scheelite flotation was not necessary. It was also found that recycling of process water did not influenceresults. Two main ore types were tested as well as tailings from 2009to 2001(0.20%WO3). In addition a flow sheet using wet high gradient magnetic separation (WHGMS) in tandem with flotation was also investigated for the tailings."

Jan 1, 2014

By L. Q. Luo

SHP-F3200 wet high-intensity magnetic separator (HIMS) was successfully used to separate the complex and weakly magnetic iron ores being composed of specularite, limonite and siderite in Ji-uquan Iron and Steel (Group) Co Ltd (JISCO). It is more and more difficult to separate iron ores from gangues, such as quartz, jasperite and phyllite, as the properties of iron ores gradually become more complicated and refractory. Some technologies have been used to improve SHP-F3200 HIMS, including modifying angle of magnetic polar from 90°to 83°, cooling exciting coils by oil instead of air, adding reverse-washing device to wash off magnetic particles, adjusting the tooth-space of matrix from 5.0 mm to 3.5 mm or 2.5 mm, so as to enhance the recovery of fine iron ore particles. It is still difficult to meet the requirement for recovering more difficultly-separated iron and the demands for high-grade concentrate of iron. In this paper, after analyzing magnetic force exerting on iron ore particles within different separating sections of SHP HIMS, it is proposed to apply the flowing-film technique into the HIMS. Thus a new-type LY matrix is designed to form magnetic gradient vertically, combined with a special flowing-film feeder to improve the existing SHP HIMS. The moving pattern of magnetic particles in pulp in HIMS separation district also has been analyzed in this paper. And the test on the SHP-F700 HIMS shows, under the condition of iron ore containing 30.52% Fe, with particle size of ?0.074 mm accounting for around 75%, if applied with flow-film technique, the iron recovery will be up from 69.45% to 76.07%, by 6.62 percent, with the same grade of concentrates of iron. The calculation of iron yield of every size fraction and the tests showed that film magnetic separation (Film-MS) could promote the iron yield of each size fraction, denoting an excellent result of application of the film technique to SHP HIMS. The mechanism of the film magnetic separation technique is to convert the turbulent flow and disordered movement of dynamic mass particles in the pulp into a directional and ordered laminar flow along the surface of tooth plate so as to strengthen the separation effects.

Jan 1, 2014

By L. S. Zhou

HermesTM metal magnetic liner (MML) has been invented and manufactured by China Metallurgy and Mining General Co. (CMMC). This paper describes its mechanism, structure, magnetic field distribution, application, economic benefit and safety performance. The 10 years? service life in Benxi Steel?s Waitoushan Mine, along with 6 years? technological analysis on its application in 5500mm×8800mm (diameter × length) ball mill in Anshan Steel?s Diaojuntai mineral processing plant, has proved its advantages such as super reliability, long service life, light weight, thin thickness, low noise and short payback period. It has also demonstrated its positive effects on the grinding process such as high productivity, energy-effective performance and low consumption of grinding media. It reduces labour intensity and improves working conditions, due to its easy installation, free maintenance and the fact that it doesn?t require fastening bolts or cause slurry leakage. It is de-signed scientifically in accordance with the varieties of processing lines, mill specification, ore type and grinding media, and has been applied in different grinding processes for magnetite, hematite, gold ores, nonferrous ores and other materials. HermesTM MML has three types of products: General, Composite and Heavy-duty. They are designed to meet the requirements from customers in China and abroad. So far, more than 400 sets of MML have been applied in ball mills with diameter rang-ing from 1500mm to 5500mm. It has become highly popular in American market recently due to its safe and effective performance.

Jan 1, 2014

By Seoul National University, Ki-Ho Kim, Jong-Pyo Kim, Sung-Min Joo, Hee-Chan Cho, Hyung-Seok Kim

Aragonite was synthesized in addition of Mg2+ ion and SrCO3 seed by carbonation process, and the best condition and mechanism of the synthesis was studied by analysis of continuous pH change, ICP, XRD, and SEM. As MgCl2•6H2O addition increased, aragonite phase increased at condition of CO2 flow rate of 100 mL/min and stirring rate of 250 rpm. It was the dissolution of Mg(OH)2 that determined overall reaction time. As SrCO3 seed addition increased at 0.2 mole MgCl2•6H2O, the amount of aragonite increased and the aspect ratio was from 5 to 9. And it was thought that Mg2+ ion prohibited calcitetransformation of aragonite formed by SrCO3.

Jan 1, 2003

By ?. ?. Zimin, B. A. Kutlin, X. Baddamsuren

"The ore features of Mongolian fluorspar deposits are shown in the paper. The possibilities of the technological of ore processing on the Bor-Undur combine scheme improvement are analyzed there. Some recommendations are done for scheme development: spare output technologies, the usage large-sized ore separation, flotation by columnar flotation cells, leaching and concentrate agglomeration.New evaluation and usage of mineral sources approach was developed for Mongolian fluoride ores. The conception allows using maximally available mineral resources for getting of metallurgical and acid fluoride concentrates while mining and technological processes: mining (as well as quarrying) -storing, blending-crushing, grinding-combined processing methods-metallurgical using preparation It has been established mining and processing technological schemes should include:• spare blasting technologies providing minimum effect on fluorite crystals which follows ore selective excavation;• large-sized ore separation methods resulted in maximum recovery for these operations in respect to metallurgical fluorite concentrates;• grinding and flotation regimes providing high-quality flotation concentrates getting for their usein chemical industry;• fluorite concentrates agglomeration technologies for providing ability of their use in metallurgical and cement industriesThe results of industrial usage of jugging machines, columnar and pneumomechanical flotation machines for fluospar dressing.The technological approaches implementation in “Bor-Undur” plant maintenance within 1993-2002 years leaded to:• change plant status from just flotation one to gravitational-flotation characterized by technological process stages which are traditional for metallurgical industry and plant capacity increase from 400 to 600 thousand tones of treatment ore as well as concentrate production increase from 120 to 150-170 thousand tones including 120-140 thousand tones of acid grade concentrates with 97% CaF2 ."

Jan 1, 2003

By V. Grujic, M. Grujic, D. Salatic

"Two areas are involved in the research work of the comminution process (crushing and grinding). The first one involves the changes of the size class distribution values that are definded by the differential equations in the function of the ore property and working conditions. The second area involves the comminution of the different levels in order to optimize the working parameters and to decrease the operational costs in the grinding process.We have studied, in detail, the possibility of functioning the crusher at the maximal loading, over 4500 kN, ball mills with diameters larger than 5.0 m and semiautogenous mills with diameters larger than 10.0 m.Using the computers, we have achieved the maximal loading range of the crusher, over Fc ? 4500 kN in the crushing process. In the grinding process, using the adequate differential equations in the automation process, we have established the correlation between the pulp mass capacity in the mill, pulp dencity, ore fineness in the pulp and recirculating ore charge.With the appopriate text, equations and graphs, this paper shows the results of our several years research work in the laboratory and in the ore comminution plant of Majdanpek Copper Mine."

Jan 1, 2003

By Diana Drinkwater, Tim Napier-Munn

"This paper argues that, although specialist mineral engineering expertise is essential for the efficient design and operation of mineral processing plants, the environment in which these skills are supplied to the industry has changed forever, and not for the better. Most of the mineral engineering programmes in western universities have died or are dying. The long-service mine site mentors have gone, operations are run on a staffing shoestring so that there is no longer the time (or inclination) for considered decision-making, and the FIFO model has discouraged continuity of optimisation projects and communication between professionals. At the same time the technical challenges of designing and operating effective process plants are increasing. These trends are not going to be reversed any time soon, if ever. The ability to run efficient mineral processing operations has been materially compromised as a consequence. We propose that well-designed professional development can help to recover this situation, and it can be done easily and cheaply. The workplace is the best environment for such skills development. Professional development training should be integrated with normal duties throughout the early years of a graduate’s service (and probably beyond), and the cost should be regarded as non-discretionary expenditure for the business. If such programmes are properly resourced and managed and extended over longer time periods, there will be a measureable rise in the level of technical understanding and competence within companies and a resulting beneficial impact on resource utilisation and thus shareholder value. The paper outlines some of the approaches that we believe will work, and the benefits that we expect will accrue."

Jan 1, 2014

By Takashi Furuyama, Sukeyuki Mori, Abel Bissombolo

"In flotation practice, a good recovery of minerals largely depends on the degree to which the valuable minerals have been liberated from the associated gangue during the grinding process. Therefore, a regular measurement of the degree of liberation can provide data for the assessment of the quality of separation and predicts the effect of changes in the grinding-classifying circuit on flotation process. Generally, the standard procedure for measuring the degree of liberation requires the preparation of polished sections - a time consuming operation that also has the disadvantage of providing an overestimated number of free particles because of the stereological nature of produced samples.The present work is an alternative approach to avoid these miscalculations and establish a system of control for fluorite flotation plants. The system deals no only with the state of liberation but also the dynamic behavior of individuals particles and mineral components within the grinding-classifying and flotation circuits. It involves methods such as sieving, x-ray diffraction analysis, study of polished sections and microscopic counting of preliminarily sieved minerals particles from a fluorite processing plant, randomly dispersed on a glass slide, but not embedded in a resin mounting medium. If a complete information on the textural properties of minerals in the ore (including its mineral components distribution) can be obtained through x-ray diffraction analysis and study of polished sections, the microscopic counting is used to determinate with enough accuracy the mineral liberation, estimate the grade of fluorite ore and products, determinate the deportment and approximate recovery of individuals particles and mineral components within the investigated circuit. For a count of 100-1000 particles in each n-size range, the counting method was found to be a particularly reliable and less time consuming operation that could substitute the chemical analysis of fluorite ore for an estimate of the grade:"

Jan 1, 2003

By Hermann Wotruba, Lars Weitkämper

"Dry coal dressing was popular during the 1950’s and 60’s in many parts of the world. The devices mainly used were air jigs and air tables.The increase in ash and moisture content of run-of-mine coals due to the wide advanced mechanisation of mining methods during and after this period led to that pneumatic devices being unable to treat run-of mine coals with the desired efficiency. Since the 1960’s almost all new coal preparation plants have been based on wet processes that are highly efficient in terms of coal recovery and their ability to handle damp and sticky run-of-mine coals. (Frankland, 1995)However, water is becoming increasingly costly and the disposal of fine products, containing most of the water, is an environmental concern. There would be significant cost savings and a lower total energy consumption if coal could be cleaned dry. Efficient dry coal treatment would be an interesting solution in desert, arid or cold areas.In Germany one dry coal dressing plant is in operation. This is the last operating dry coal dressing plant existing in Europe. The actual technical standard of dry coal dressing has been analysed during test-work and sampling in this plant (Saar Region in Germany). The process and the advantages and disadvantages are presented. The plants problems are low efficiency in the fine fraction –6 mm and the coarse fraction +30 mm and a low overall throughput as well as the lack of an automatic process control system. The separation results in the medium size fractions between +6 and -30 mm are excellent"

Jan 1, 2003

By Stephen Gay, Dewetia Latti

"When improving a plant a mineral processing engineer would like to know the mineral composition distribution. In order to assess this distribution in particles, as compared to the corresponding distribution in particle sections, a procedure needs to be applied to the observed particle sections. Such a procedure is called a stereological correction. There exists many stereological correction procedures, but one group of such procedures is based on using those stereological equations that do not require making assumptions regarding particle shape or texture. These equations are called geometric probability equations.Davy derived a geometric probability equation to estimate the covariance of mineral composition distributions for particles from both particle sections and linear intercepts. This covariance can be used to measure the variance of the particle composition distribution of each mineral. The equation as presented by Davy requires textural information; however the equation was modified by Gay to be more directly applied to particle sections and linear intercepts. The variance obtained from applying this equation is fundamental to the binary stereological correction procedures developed by Gay and his colleagues; the covariance is fundamental to the multiphase stereological correction.Thus far, validation of both the binary and multiphase stereological correction has been achieved using numerical simulation. This paper shall present results comparing the covariance (and variance) estimates from Gay’s equation with actual three-dimensional information obtained from serially sectioning particles. This involved mounting a set of particles and continuously sectioning all particles uniformly so that the three dimensional structure of the particles could be obtained.The mineralogical data to which the equations described above were applied were derived from two individual size fractions from a hard-rock titanium deposit. The deposit contains a range of minerals and of mineral textures and the two size fractions selected were:"

Jan 1, 2003

By J. Faitli, I. Tarján

One of the basic processes of process engineering is the production of dense suspensions. The major two equipment of this task are the periodically operating propeller mixer, and the continuously operating mixer tank based on the flow principle. In the laboratory of the Department of Process Engineering at the University of Miskolc, laboratory scale experimental setups had been built of both types of mixers in the frame of the FKFP 0504/1999 signed research project, supported by the Hungarian Ministry of Education. By these experimental setups many systematical experimental series had been carried out by test materials of water as the dispersing media and sand, power plant fly ash and magnetite as the granular solids. On the basis of the literature and these experimental investigations, scale-up methods had been developed for both types of mixers for the determination of the main technical parameters of industrial size equipment.

Jan 1, 2003