Darbo tikslas – nustatyti mineralinių medžiagų kiekį skirtingų veislių galvijų ir kiaulių mėsoje bei jų koreliaciją su mėsos kokybės rodikliais. Darbo uždaviniai: 1. Tirti ir įvertinti skirtingų veislių kiaulių ir jų derinių bei skirtingų veislių galvijų ilgiausiojo nugaros raumens cheminę sudėtį ir technologines savybes. 2. Nustatyti skirtingų veislių kiaulių ir galvijų ilgiausiame nugaros raumenyje esantį mineralinių medžiagų kiekį (Na, Mg, Ca, Fe, Ni, Cu, Zn, Ba). 3. Nustatyti tirtų mineralinių medžiagų kiekio ryšį su mėsos kokybės rodikliais. Darbo naujumas. Mėsinių galvijų ir kiaulių mėsoje mineralinių medžiagų kiekio, priklausomai nuo veislės, duomenys yra labai riboti, o kai su kuriomis veislėmis tokie tyrimai išvis nevykdyti. Nustatytas svarbių žmonių sveikatingumui mineralinių medžiagų kiekis, skirtingų genotipų galvijų ir kiaulių mėsoje, šeriant ir auginant gyvulius vienodose sąlygose. Apskaičiuota mineralinių medžiagų kiekio koreliacija su mėsos kokybės rodikliais. Praktinė reikšmė. Atlikti mėsos kokybės tyrimai nustatant mikro- ir makro- elementų koncentracijas įvairių veislių galvijų ir kiaulių mėsoje ir jų ryšio nustatymas su mėsos kokybės rodikliais, yra reikšmingi vertinant mėsos maistinę vertę žmonių mityboje. Maistinių medžiagų kiekis liesoje mėsoje gali skirtis didesniu mastu nei kituose maisto produktuose, dėl gyvulio genetinių ar technologinių savybių. Tikslus nustatymas mikro ir makro elementų, auginant ir šeriant gyvulius vienodomis sąlygomis, sąlygos... [toliau žr. visą tekstą] / The aim of the research – to determine the mineral content in various breeds‘ cattle and pigs meat and its‘ correlation with meat quality indexes. Tasks of the research: 1. To analyse and estimate chemical composition and technological qualities of various different breeds‘ and derivatives‘ pigs and cattle musculus longissimus dorsi. 2. To estimate the mineral content (of Na, Mg, Ca, Fe, Ni, Cu, Zn, Ba) that various breeds‘ pigs and cattle musculus longissimus dorsi contain. 3. To estimate the connection between analysed minerals and indexes of meat quality. Originality of the research. The amount of micro- and macro-elements in cattle and pig meat various according its genotype. The material of such type research are very limited. The amount of minerals in different genotypes‘ cattle and pigs meat was determined after their feeding and keeping in standardised conditions. A correlation of minerals and meat quality indexes was estimated. Practical significance. The fulfilled meat qualitys‘ research determining the concentrations of micro- and macro- element amounts in various breeds‘ cattle and pig meat is significant while evaluating nutritional meats‘ value in human nutrition. The amount of nutrients in low-fat meat might differ from other processed food by a major extent because of animals‘ genetic and technologic characteristics. A precise estimation of micro- and macro- elements, in animals that were held and fed in standardised conditions meat, is going to determine a... [to full text]

The influence of drying parameters namely residence time before drying, drying temperature, drying time, relative humidity, and slip recipe on the drying rate of slip cast sanitary wares, predominantly lavatories and toilet closets, was studied. The drying temperatures were changed from 80 oC to 110 oC with an increment of 10 oC. The drying time was changed from 10 to 7 h with a decrease of 1 hour. Relative humidity of the environment was changed from 60 to 75 %. The percent weight loss, percent residual moisture and the percent shrinkage of the samples were determined by weighing and measuring the samples before and after the tests. The percent weight loss was within the range of 6.5 to 6.6 % after holding the as cast samples for 6 hours at ambient casting shop conditions while it was within the range of 17.96 to 18.10 % when subsequently dried for 10 hours at 110 oC in the dryer. The percent shrinkage was within the range of 2.9 - 3.0 % after holding the as cast samples 6 h at ambient laboratory conditions. No shrinkage was observed in the sample when it was subsequently dried for 10 hours at 110 oC in the dryer. Optimum moisture content of dried wares was obtained after drying for 8 hours at 100 oC in the dryer. It has been seen that the relative humidity of the dryer at the beginning of the drying should be lower than 75 %. As the non-plastic content in the recipe of the sanitary ware slip increased, drying shrinkage and residual moisture content decreased. The results of this study showed that through increasing the residence time up to 6h with a casting shop environment of approximately 30 oC and 60 % relative humidity, the drying time could be safely reduced from 10 h to 8 h with a drying temperature of 100 oC for the test plates. The same approach can be used for more complex shapes, e.g., WC closets, basins, tanks etc. in EczacibaSi Vitra plant. Once the drying time was reduced, the amount of natural gas per ware would be reduced to a certain extent. Aside from that the reduction in the drying time would increase the quantity of the drying cycles per week so that more wares could be dried. When all these observations were taken into account, this thesis study could also be utilized by other sanitary ware producing companies whose processes require slip cast drying.

The electronic spectra of sulfide minerals can be complex, and their features difficult to assign. Often, therefore, they are interpreted using electronic-structure models obtained from quantum-chemical calculations. The aim of this study is to provide such models for the minerals sphalerite, wurtzite, pyrite, marcasite, and chalcopyrite. All are important minerals within a mining context, either as a source for their component metals or as a gangue mineral. They are also semiconductors. Each is the structural archetype for a particular class of semiconductors, and so a knowledge of their electronic structures has wider applicability. / PhD Doctorate

Abstract Screen modelling has traditionally been based on rudimentary empirical ‘factor’ methods, or semi-empirical data-fitting techniques. Both of these methods have significant limitations in practice, and industrial screen optimization remains somewhat of a ‘black art’. This thesis introduces the concept of dimensional analysis and scale model similitude to the problem of modelling vibrating screens. This leads to a new method of modelling industrial screens. A small-scale screen can be built at a more convenient scale in the laboratory, and used to predict the performance of a large industrial scale machine. Verification of the scaling theory is based on three separate methods: 1. Firstly, the scaling theory is developed by analysing particle-level forces acting in a dry granular system. It is shown that scale-up of granular systems can be achieved using Froude scaling: that is, if the geometry and operating variables in an experiment are scaled in a pre-defined manner, the behaviour of the particles in the full-scale can be predicted from the behaviour of the particles at the smaller scale. 2. Secondly, the scaling rules are applied to a number of idealized granular systems using numerical simulations via the discrete element method (DEM). The granular systems modelled include inclined vibrating feeders and inclined vibrating screens. It is found that simulations performed at different scales yield almost identical dimensionless responses when the geometry and operating conditions are scaled according to Froude scaling rules. 3. Thirdly, the scaling rules are applied to modelling physical screening data. A dataset obtained from a larger pilot-scale screen in a thesis by R. De Pretto (1992) is reproduced at a smaller scale in this thesis using a purpose-built laboratory-scale screen. The throughput, efficiency curves and cut size are shown to be predictable at all feed rates, despite the former dataset being based on a screen with a feed sample size of around 5000 kg per test and the latter dataset obtained using a feed sample size of less than 30 kg per test. The thesis also touches on modelling the screening efficiency curves. A fully dimensionless version of the proven and familiar Whiten screen model is proposed. Scale-up and modelling of industrial screens M. M. Hilden viii Finally, some of the further possibilities of this theory are discussed briefly in a section on further work; these include further applications of the Screening Physical Model and the application of Froude scaling to the modelling of other granular systems.

[Truncated abstract] Magnetic gradiometers are powerful tools for mineral exploration. The magnetic field contains valuable information about the mineral content of the surveyed terrain. The magnetic gradient specifies the amount of spatial variation in the direction and magnitude of the magnetic field. Surveys that measure the magnetic gradient provide vastly more information about geological targets than the magnetic field alone. This technology could have enormous benefits in terms of new discoveries and lower exploration costs. The magnetic gradient is normally calculated by subtracting the outputs of two total field magnetometers which are separated by a baseline. In 1997, a direct string magnetic gradiometer (DSMG) was developed that directly measures magnetic gradients using only a single string as its sensing element. This thesis describes research conducted to improve the sensitivity and performance of the DSMG. The main advantage of the DSMG is that only gradients can induce second harmonic vibrations in the string. Thus, the DSMG is insensitive to uniform magnetic fields that we are not interested in, such as the global magnetic field of the Earth. By using inductive electronics to measure second harmonic string vibrations, we can select to measure the magnetic gradient of nearby targets. Recent work has shown that a magnetic gradiometer with a noise floor of 0.01 nT/m/ v Hz should be sufficiently sensitive for geophysical exploration. In order to reach this goal, this thesis presents an investigation of all noise sources affecting the DSMG. ... Gas damping is negligible in high vacuum and no vibration isolation is required. This means that longer strings with low resonant frequencies can be used. Using theoretical modelling, I show that a space borne DSMG should be able to match the white noise level of SQuID based magnetic gradiometers and have a lower 1/f noise corner. Deployment in space could be the most viable application of the DSMG because of the ease of operation and enhancement of sensitivity. If the thermal noise level is reduced then other sources of noise will start to become more important. When rotated in the Earth's magnetic field, the DSMG detects a pseudo magnetic gradient despite the field being almost uniform. A possible cause is magnetically susceptible parts which are magnetically aligning with the Earth's field. I have conducted a thorough investigation of magnetic susceptible parts in the DSMG and reported the results in this thesis. In the DSMG, a pair of inductive pickup coils are used to measure the string's displacement with a root mean square accuracy of 1011 m/ v Hz. This is adequate at present but the inductive electronics may not be sensitive enough after other improvements in the DSMG are implemented. Here, I present a new capacitive displacement readout with a high sensitivity of 1013 m/ v Hz. The thesis also presents some magnetic gradient measurements in the lab and the results of a ground survey in the field. These trial measurements are used to characterise the DSMG and demonstrate its effectiveness for airborne surveying.

The role of mathematical models and simulators in describing the performance of mineral processing applications have had a large impact in optimising existing industrial plants and designing new plants over recent years. Before the development of sophisticated computer simulators, the design engineer used industrial “rules of thumb” to estimate the size and layout of plants. However, newly designed plants after commissioning, often do not meet the design product specification requirements and quite often years of “trial and error” optimisation is required. This process can be very costly especially with froth flotation processes where the complexity of the various stages of treatment makes “trial and error” optimisation very difficult to quantify and assess the benefits. Over the past 10 years, advances in the modelling of the flotation process have been conducted by many authors. The most significant flotation modelling advances in recent years have been provided by the AMIRA (Australian Mineral Industry Research Association) P9 project, whereby a new modelling methodology has been proposed. Within this methodology, the flotation response can be represented by a number of sub-processes including parameters describing the hydrodynamic, froth and ore characteristics. Although these parameters have been proposed, methods for measuring these parameters in large flotation cells are still developing, especially in the areas of the froth zone recovery and entrainment. In the light of this it was felt that the literature on froth recovery determination should be investigated to determine the most appropriate method for measuring froth recovery in large industrial flotation cells. It was found after the investigation of the literature that three techniques for measuring the froth recovery parameter stood out as potential methods for measurement within a large scale flotation cell. These were the methods decribed by Gorain et al (1998), Vera et al (1999) and Savassi et al (1997). It was decided that all three methods should be assessed on a quantitative and qualitative basis from data collected at the Mount Isa Mines (now Xstrata) Copper flotation circuit. In this assessment, all three methods were extensively trialed in a 2.8 m3 flotation cell which was operated in parallel to the main copper rougher flotation circuit. The cell could be operated at numerous operating conditions which allowed sufficient data to be collected. The conclusions from this work were that although the method proposed by Vera et al (1999) required significant amounts of data, the method appeared to be reliable in this scale of cell. The main recommendation from this work was to further test the Vera methodology in larger industrial flotation cells. A 100 m3 Outukumpu tank cell at the Mount Keith Nickel Concentrator was chosen for the further assessment of the Vera et al (1999) methodology and its applicability to large scale cells. This flotation cell was one of the largest flotation cells operating on a production scale at the time of the testwork. Numerous tests were conducted and data collected from this investigation showed that the Vera et al (1999) technique was applicable to this scale of flotation cell. Since the work at Mount Keith was conducted in a rougher flotation cell, it was decided to test the methodology with numerous cells of various sizes and duties at the Kambalda Nickel Concentrator. As with the previous investigation at Mount Keith, it was observed that the Vera method was able to measure froth recoveries in all cells measured at Kambalda (within typical operating ranges). However, the technique was not applicable at shallow froth depths since it does not take into account the effect of the pulp-froth interface within the froth recovery parameter estimation. The pulp froth interface and close to it is where a significant proportion of dropback occurs within the froth zone. In addition to this problem, the methodology required large numbers of samples and disturbed downstream processes which made the technique unpractical for operating industrial flotation plants. Hence, a new technique for measuring froth recovery in large flotation cells was required. For the technique to be successful on an industrial scale it required the following: • minimum disturbance on the process, • take into account the pulp froth interface within the froth recovery parameter, and • require a minimum amount of samples. To meet these needs a new technique was developed based on the Savassi et al (1997) technique and combining it with recent work by authors including Vera et al (2003). The methodology involves taking samples of the feed, concentrate and tail as per a typical flotation survey and combining them with two new samples: the air hold-up sample and the top of froth sample. With the addition of these samples, a mass balance across the pulp and froth phase could be conducted and the froth recovery parameter derived. In addition, the new method provided measurements of the pulp zone average bubble load and the amount recovered by the entrainment mechanism. The proposed method has a simple procedure which allows the technique to be used by academics and mill operators alike. The proposed froth recovery measurement technique was tested in numerous cells of various types (i.e. Wemco, Outokumpu, Dorr-Oliver etc), various sizes (up to 150 m3 in size), various duties (rougher, scavenger, cleaner, recleaner, etc) and various plants. In most cases the methodology proved to be a reliable measure of the froth recovery parameter. In addition, at the Century Zinc Operation, the methodology was compared directly with the original Vera et al (1999) technique and the results showed that there was a good comparison between the results with the off-set of the pulp-froth interface. A number of contributions to both the research and industrial areas have been provided from the outcomes of the thesis. The main contributions include: • A full assessment of the three current methods for measuring the froth recovery parameter within large flotation cells. With recommendations of developing a new technique. • The development of a froth recovery measurement technique which can be used in large cells to understand the impact of the froth zone in an individual cell, use within the AMIRA P9 modelling methodology and plant diagnostics. • The new method also allows the estimation of the average bubble load and quantifies the amount of material recovered by the entrainment mechanism which is invaluable to metallurgists in assessing the performance of a flotation circuit (plant diagnostics). Finally, the results of this thesis will provide practising metallurgists both within the research and operating fields, techniques to improve the profitability of flotation circuits worldwide. Metallurgists can quickly assess the performance of large flotation cells in terms of froth performance, bubble load and entrainment which has not been available before. In addition, the results from this thesis will also allow metallurgists to mathematically represent their plant through flotation models better and improve their understanding of their flotation circuits.

The role of mathematical models and simulators in describing the performance of mineral processing applications have had a large impact in optimising existing industrial plants and designing new plants over recent years. Before the development of sophisticated computer simulators, the design engineer used industrial “rules of thumb” to estimate the size and layout of plants. However, newly designed plants after commissioning, often do not meet the design product specification requirements and quite often years of “trial and error” optimisation is required. This process can be very costly especially with froth flotation processes where the complexity of the various stages of treatment makes “trial and error” optimisation very difficult to quantify and assess the benefits. Over the past 10 years, advances in the modelling of the flotation process have been conducted by many authors. The most significant flotation modelling advances in recent years have been provided by the AMIRA (Australian Mineral Industry Research Association) P9 project, whereby a new modelling methodology has been proposed. Within this methodology, the flotation response can be represented by a number of sub-processes including parameters describing the hydrodynamic, froth and ore characteristics. Although these parameters have been proposed, methods for measuring these parameters in large flotation cells are still developing, especially in the areas of the froth zone recovery and entrainment. In the light of this it was felt that the literature on froth recovery determination should be investigated to determine the most appropriate method for measuring froth recovery in large industrial flotation cells. It was found after the investigation of the literature that three techniques for measuring the froth recovery parameter stood out as potential methods for measurement within a large scale flotation cell. These were the methods decribed by Gorain et al (1998), Vera et al (1999) and Savassi et al (1997). It was decided that all three methods should be assessed on a quantitative and qualitative basis from data collected at the Mount Isa Mines (now Xstrata) Copper flotation circuit. In this assessment, all three methods were extensively trialed in a 2.8 m3 flotation cell which was operated in parallel to the main copper rougher flotation circuit. The cell could be operated at numerous operating conditions which allowed sufficient data to be collected. The conclusions from this work were that although the method proposed by Vera et al (1999) required significant amounts of data, the method appeared to be reliable in this scale of cell. The main recommendation from this work was to further test the Vera methodology in larger industrial flotation cells. A 100 m3 Outukumpu tank cell at the Mount Keith Nickel Concentrator was chosen for the further assessment of the Vera et al (1999) methodology and its applicability to large scale cells. This flotation cell was one of the largest flotation cells operating on a production scale at the time of the testwork. Numerous tests were conducted and data collected from this investigation showed that the Vera et al (1999) technique was applicable to this scale of flotation cell. Since the work at Mount Keith was conducted in a rougher flotation cell, it was decided to test the methodology with numerous cells of various sizes and duties at the Kambalda Nickel Concentrator. As with the previous investigation at Mount Keith, it was observed that the Vera method was able to measure froth recoveries in all cells measured at Kambalda (within typical operating ranges). However, the technique was not applicable at shallow froth depths since it does not take into account the effect of the pulp-froth interface within the froth recovery parameter estimation. The pulp froth interface and close to it is where a significant proportion of dropback occurs within the froth zone. In addition to this problem, the methodology required large numbers of samples and disturbed downstream processes which made the technique unpractical for operating industrial flotation plants. Hence, a new technique for measuring froth recovery in large flotation cells was required. For the technique to be successful on an industrial scale it required the following: • minimum disturbance on the process, • take into account the pulp froth interface within the froth recovery parameter, and • require a minimum amount of samples. To meet these needs a new technique was developed based on the Savassi et al (1997) technique and combining it with recent work by authors including Vera et al (2003). The methodology involves taking samples of the feed, concentrate and tail as per a typical flotation survey and combining them with two new samples: the air hold-up sample and the top of froth sample. With the addition of these samples, a mass balance across the pulp and froth phase could be conducted and the froth recovery parameter derived. In addition, the new method provided measurements of the pulp zone average bubble load and the amount recovered by the entrainment mechanism. The proposed method has a simple procedure which allows the technique to be used by academics and mill operators alike. The proposed froth recovery measurement technique was tested in numerous cells of various types (i.e. Wemco, Outokumpu, Dorr-Oliver etc), various sizes (up to 150 m3 in size), various duties (rougher, scavenger, cleaner, recleaner, etc) and various plants. In most cases the methodology proved to be a reliable measure of the froth recovery parameter. In addition, at the Century Zinc Operation, the methodology was compared directly with the original Vera et al (1999) technique and the results showed that there was a good comparison between the results with the off-set of the pulp-froth interface. A number of contributions to both the research and industrial areas have been provided from the outcomes of the thesis. The main contributions include: • A full assessment of the three current methods for measuring the froth recovery parameter within large flotation cells. With recommendations of developing a new technique. • The development of a froth recovery measurement technique which can be used in large cells to understand the impact of the froth zone in an individual cell, use within the AMIRA P9 modelling methodology and plant diagnostics. • The new method also allows the estimation of the average bubble load and quantifies the amount of material recovered by the entrainment mechanism which is invaluable to metallurgists in assessing the performance of a flotation circuit (plant diagnostics). Finally, the results of this thesis will provide practising metallurgists both within the research and operating fields, techniques to improve the profitability of flotation circuits worldwide. Metallurgists can quickly assess the performance of large flotation cells in terms of froth performance, bubble load and entrainment which has not been available before. In addition, the results from this thesis will also allow metallurgists to mathematically represent their plant through flotation models better and improve their understanding of their flotation circuits.

The role of mathematical models and simulators in describing the performance of mineral processing applications have had a large impact in optimising existing industrial plants and designing new plants over recent years. Before the development of sophisticated computer simulators, the design engineer used industrial “rules of thumb” to estimate the size and layout of plants. However, newly designed plants after commissioning, often do not meet the design product specification requirements and quite often years of “trial and error” optimisation is required. This process can be very costly especially with froth flotation processes where the complexity of the various stages of treatment makes “trial and error” optimisation very difficult to quantify and assess the benefits. Over the past 10 years, advances in the modelling of the flotation process have been conducted by many authors. The most significant flotation modelling advances in recent years have been provided by the AMIRA (Australian Mineral Industry Research Association) P9 project, whereby a new modelling methodology has been proposed. Within this methodology, the flotation response can be represented by a number of sub-processes including parameters describing the hydrodynamic, froth and ore characteristics. Although these parameters have been proposed, methods for measuring these parameters in large flotation cells are still developing, especially in the areas of the froth zone recovery and entrainment. In the light of this it was felt that the literature on froth recovery determination should be investigated to determine the most appropriate method for measuring froth recovery in large industrial flotation cells. It was found after the investigation of the literature that three techniques for measuring the froth recovery parameter stood out as potential methods for measurement within a large scale flotation cell. These were the methods decribed by Gorain et al (1998), Vera et al (1999) and Savassi et al (1997). It was decided that all three methods should be assessed on a quantitative and qualitative basis from data collected at the Mount Isa Mines (now Xstrata) Copper flotation circuit. In this assessment, all three methods were extensively trialed in a 2.8 m3 flotation cell which was operated in parallel to the main copper rougher flotation circuit. The cell could be operated at numerous operating conditions which allowed sufficient data to be collected. The conclusions from this work were that although the method proposed by Vera et al (1999) required significant amounts of data, the method appeared to be reliable in this scale of cell. The main recommendation from this work was to further test the Vera methodology in larger industrial flotation cells. A 100 m3 Outukumpu tank cell at the Mount Keith Nickel Concentrator was chosen for the further assessment of the Vera et al (1999) methodology and its applicability to large scale cells. This flotation cell was one of the largest flotation cells operating on a production scale at the time of the testwork. Numerous tests were conducted and data collected from this investigation showed that the Vera et al (1999) technique was applicable to this scale of flotation cell. Since the work at Mount Keith was conducted in a rougher flotation cell, it was decided to test the methodology with numerous cells of various sizes and duties at the Kambalda Nickel Concentrator. As with the previous investigation at Mount Keith, it was observed that the Vera method was able to measure froth recoveries in all cells measured at Kambalda (within typical operating ranges). However, the technique was not applicable at shallow froth depths since it does not take into account the effect of the pulp-froth interface within the froth recovery parameter estimation. The pulp froth interface and close to it is where a significant proportion of dropback occurs within the froth zone. In addition to this problem, the methodology required large numbers of samples and disturbed downstream processes which made the technique unpractical for operating industrial flotation plants. Hence, a new technique for measuring froth recovery in large flotation cells was required. For the technique to be successful on an industrial scale it required the following: • minimum disturbance on the process, • take into account the pulp froth interface within the froth recovery parameter, and • require a minimum amount of samples. To meet these needs a new technique was developed based on the Savassi et al (1997) technique and combining it with recent work by authors including Vera et al (2003). The methodology involves taking samples of the feed, concentrate and tail as per a typical flotation survey and combining them with two new samples: the air hold-up sample and the top of froth sample. With the addition of these samples, a mass balance across the pulp and froth phase could be conducted and the froth recovery parameter derived. In addition, the new method provided measurements of the pulp zone average bubble load and the amount recovered by the entrainment mechanism. The proposed method has a simple procedure which allows the technique to be used by academics and mill operators alike. The proposed froth recovery measurement technique was tested in numerous cells of various types (i.e. Wemco, Outokumpu, Dorr-Oliver etc), various sizes (up to 150 m3 in size), various duties (rougher, scavenger, cleaner, recleaner, etc) and various plants. In most cases the methodology proved to be a reliable measure of the froth recovery parameter. In addition, at the Century Zinc Operation, the methodology was compared directly with the original Vera et al (1999) technique and the results showed that there was a good comparison between the results with the off-set of the pulp-froth interface. A number of contributions to both the research and industrial areas have been provided from the outcomes of the thesis. The main contributions include: • A full assessment of the three current methods for measuring the froth recovery parameter within large flotation cells. With recommendations of developing a new technique. • The development of a froth recovery measurement technique which can be used in large cells to understand the impact of the froth zone in an individual cell, use within the AMIRA P9 modelling methodology and plant diagnostics. • The new method also allows the estimation of the average bubble load and quantifies the amount of material recovered by the entrainment mechanism which is invaluable to metallurgists in assessing the performance of a flotation circuit (plant diagnostics). Finally, the results of this thesis will provide practising metallurgists both within the research and operating fields, techniques to improve the profitability of flotation circuits worldwide. Metallurgists can quickly assess the performance of large flotation cells in terms of froth performance, bubble load and entrainment which has not been available before. In addition, the results from this thesis will also allow metallurgists to mathematically represent their plant through flotation models better and improve their understanding of their flotation circuits.

The role of mathematical models and simulators in describing the performance of mineral processing applications have had a large impact in optimising existing industrial plants and designing new plants over recent years. Before the development of sophisticated computer simulators, the design engineer used industrial “rules of thumb” to estimate the size and layout of plants. However, newly designed plants after commissioning, often do not meet the design product specification requirements and quite often years of “trial and error” optimisation is required. This process can be very costly especially with froth flotation processes where the complexity of the various stages of treatment makes “trial and error” optimisation very difficult to quantify and assess the benefits. Over the past 10 years, advances in the modelling of the flotation process have been conducted by many authors. The most significant flotation modelling advances in recent years have been provided by the AMIRA (Australian Mineral Industry Research Association) P9 project, whereby a new modelling methodology has been proposed. Within this methodology, the flotation response can be represented by a number of sub-processes including parameters describing the hydrodynamic, froth and ore characteristics. Although these parameters have been proposed, methods for measuring these parameters in large flotation cells are still developing, especially in the areas of the froth zone recovery and entrainment. In the light of this it was felt that the literature on froth recovery determination should be investigated to determine the most appropriate method for measuring froth recovery in large industrial flotation cells. It was found after the investigation of the literature that three techniques for measuring the froth recovery parameter stood out as potential methods for measurement within a large scale flotation cell. These were the methods decribed by Gorain et al (1998), Vera et al (1999) and Savassi et al (1997). It was decided that all three methods should be assessed on a quantitative and qualitative basis from data collected at the Mount Isa Mines (now Xstrata) Copper flotation circuit. In this assessment, all three methods were extensively trialed in a 2.8 m3 flotation cell which was operated in parallel to the main copper rougher flotation circuit. The cell could be operated at numerous operating conditions which allowed sufficient data to be collected. The conclusions from this work were that although the method proposed by Vera et al (1999) required significant amounts of data, the method appeared to be reliable in this scale of cell. The main recommendation from this work was to further test the Vera methodology in larger industrial flotation cells. A 100 m3 Outukumpu tank cell at the Mount Keith Nickel Concentrator was chosen for the further assessment of the Vera et al (1999) methodology and its applicability to large scale cells. This flotation cell was one of the largest flotation cells operating on a production scale at the time of the testwork. Numerous tests were conducted and data collected from this investigation showed that the Vera et al (1999) technique was applicable to this scale of flotation cell. Since the work at Mount Keith was conducted in a rougher flotation cell, it was decided to test the methodology with numerous cells of various sizes and duties at the Kambalda Nickel Concentrator. As with the previous investigation at Mount Keith, it was observed that the Vera method was able to measure froth recoveries in all cells measured at Kambalda (within typical operating ranges). However, the technique was not applicable at shallow froth depths since it does not take into account the effect of the pulp-froth interface within the froth recovery parameter estimation. The pulp froth interface and close to it is where a significant proportion of dropback occurs within the froth zone. In addition to this problem, the methodology required large numbers of samples and disturbed downstream processes which made the technique unpractical for operating industrial flotation plants. Hence, a new technique for measuring froth recovery in large flotation cells was required. For the technique to be successful on an industrial scale it required the following: • minimum disturbance on the process, • take into account the pulp froth interface within the froth recovery parameter, and • require a minimum amount of samples. To meet these needs a new technique was developed based on the Savassi et al (1997) technique and combining it with recent work by authors including Vera et al (2003). The methodology involves taking samples of the feed, concentrate and tail as per a typical flotation survey and combining them with two new samples: the air hold-up sample and the top of froth sample. With the addition of these samples, a mass balance across the pulp and froth phase could be conducted and the froth recovery parameter derived. In addition, the new method provided measurements of the pulp zone average bubble load and the amount recovered by the entrainment mechanism. The proposed method has a simple procedure which allows the technique to be used by academics and mill operators alike. The proposed froth recovery measurement technique was tested in numerous cells of various types (i.e. Wemco, Outokumpu, Dorr-Oliver etc), various sizes (up to 150 m3 in size), various duties (rougher, scavenger, cleaner, recleaner, etc) and various plants. In most cases the methodology proved to be a reliable measure of the froth recovery parameter. In addition, at the Century Zinc Operation, the methodology was compared directly with the original Vera et al (1999) technique and the results showed that there was a good comparison between the results with the off-set of the pulp-froth interface. A number of contributions to both the research and industrial areas have been provided from the outcomes of the thesis. The main contributions include: • A full assessment of the three current methods for measuring the froth recovery parameter within large flotation cells. With recommendations of developing a new technique. • The development of a froth recovery measurement technique which can be used in large cells to understand the impact of the froth zone in an individual cell, use within the AMIRA P9 modelling methodology and plant diagnostics. • The new method also allows the estimation of the average bubble load and quantifies the amount of material recovered by the entrainment mechanism which is invaluable to metallurgists in assessing the performance of a flotation circuit (plant diagnostics). Finally, the results of this thesis will provide practising metallurgists both within the research and operating fields, techniques to improve the profitability of flotation circuits worldwide. Metallurgists can quickly assess the performance of large flotation cells in terms of froth performance, bubble load and entrainment which has not been available before. In addition, the results from this thesis will also allow metallurgists to mathematically represent their plant through flotation models better and improve their understanding of their flotation circuits.

[Truncated abstract] Many researchers have proposed the use of silicate rock fertilizers (SRFs) as alternatives to chemical fertilizers. However, the application of SRFs in modern agricultural practices is limited due mainly to the slow release of plant-nutrient elements from SRFs and consequently many tonnes/ha of SRFs may need to be applied. Simple and inexpensive methods of modifying the physicochemical properties of SRFs are needed to improve the agronomic effectiveness of SRFs. This thesis is focused on the evaluation of high-energy milling to produce superfine particles to improve the effectiveness of mafic (basalt and dolerite) and felsic (gneiss and K-feldspar) rocks for use as fertilizers. The ground mafic rocks are for use as Ca and Mg fertilizers and the ground felsic rocks as K fertilizers. Laboratory and glasshouse experiments were conducted with several potential SRFs. In laboratory experiments, initially milled rocks (Ø< 250 μm for basalt, dolerite, and gneiss; Ø < 150 μm for K-feldspar) were further milled with a ball mill (Spex-8000) for 10, 30, 60, 90, and 120 min under dry and wet (rock/water ratio = 1/3) conditions. To investigate possible reaction between constituents, other subsamples of initially milled basalt, dolerite, and gneiss were added to reagent grade NaCl or KCl (4.5 g rock + 0.5 g NaCl or KCl) and milled for 120 min under dry and wet conditions. Basalt and dolerite were also mixed with K-feldspar at a ratio of 1 : 1 and milled for 120 min under dry and wet conditions. For use in the glasshouse experiment, the initially milled rocks were further milled with a vertical stirred ball mill for 1 h in a dry condition. The elemental and mineralogical compositions of the SRFs were determined using XRF and XRD. Effects of milling on major physicochemical properties of milled rocks were determined, including particle size (Malvern Mastersizer), surface area (BET-N2), quantities of amorphous constituents (XRD, oxalic acid-oxalate extraction, TEM), extractable cations (1M CH3COONH4 pH 7), pHH2O, and electric conductivity. Dissolution kinetics in 0.01M acetic-citric acids (for 56 days) and soil (for 10 months) were determined. Based on the results of these laboratory experiments, a glasshouse experiment was carried out for 12 months to evaluate the effects of SRF application on growth and nutrient uptake of ryegrass grown on several soils. Milling reduced particle size, enhanced amorphism, and increased the release of structural cations from the rocks, with the effects due to dry milling being greater than for wet milling. The optimum milling times which produced maximum amounts of exchangeable cations (Na, K, Ca, and Mg) were 30 - 90 min, depending on rock type. The use of NaCl and KCl as milling additives did not enhance the properties of the SRF