| 1. |
- Ajayi, John Ade, et al.
(författare)
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Recovery efficiency study on ilesha placer gold ore by flotation using locallysourced frothers and collectors
- 2010
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Ingår i: XXV International Mineral Processing Congress. - Carlton, Vic : The Australasian Institute of Mining and Metallurgy. - 9781921522284 ; , s. 1695-1702
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Konferensbidrag (refereegranskat)abstract
- The research conducted by the defunct Nigerian Mining Corporation revealed that minable quantities of gold deposit are present over an expanse of Ilesha-Ife area. This optimism prompted several researchers to study the response of Ilesha gold ore to amalgamation and cyanidation. Unfortunately, these methods (amalgamation and cyanidation) are environmentally hazardous and the reagents are rather expensive when available. This is the thrust for this research which is aimed at studying the amenability of Ilesha placer gold ore to froth flotation which is environmentally friendly using locally-sourced reagents. The mineralogical study of the deposit was carried out and the result showed that the Ilesha placer deposit is non-refractory with fine-grained gold particles. Potassium salts of groundnut and palm kernel oils (as collectors) and their fatty acids (as frothers) were prepared and used to float gold concentrate from Ilesha placer gold ore. The following flotation parameters: pulp density, impeller speed, pulp pH, collector concentration and particle size analysis were optimised. The results obtained shows that optimum recovery of 91.8 per cent and 89.56 per cent of gold concentrates were obtained at pulp pH of 9, pulp density of 100 g/cm3, impeller velocity of 1350 rpm and mineral particle size range of -75 μm when potassium salts of groundnut and palmkernel oils were used respectively as collectors. Thus Ilesha placer gold ore is amenable to froth flotation using locally-sourced frothers and collectors.
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| 2. |
- Hulthén, Erik, 1980, et al.
(författare)
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Two Variable Real-Time Algorithm for Cone Crusher Control
- 2010
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Ingår i: XXV INTERNATIONAL MINERAL PROCESSING CONGRESS IMPC 2010. - 9781921522284 ; , s. 813-819
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Konferensbidrag (refereegranskat)abstract
- Cone crushers are used in the mineral, mining, and aggregate industry for fragmentation of rockmaterials. Control systems for cone crusher setting (CSS) are widely used to compensate for wearand to protect the crusher. With a frequency converter the eccentric speed in a cone crusher canbe adjusted in real-time. The eccentric speed of the main shaft affects the number of compressionsthe material is exposed to and thus the capacity and the particle size distribution of the product. Byapplying mass-fl ow sensors to the process, a feedback of the different product yields is obtained inevery moment.In this paper, a model and an algorithm are presented. The algorithm takes the incrementallyincreasing CSS into account and compensates for this with a successively changing eccentric speed.In order to implement the algorithm, a monitoring and control system is developed, including theonline algorithm for selection eccentric speed. The different product fl ows from the crushing plantare continuously monitored by mass fl ow meters. The fi tness function is set by the plant managementdepending on production targets and market situation. An earlier developed Finite State Machine(FSM) algorithm is also implemented and evaluated in the system.The developed algorithm has been validated and verifi ed at a crushing plant for aggregates with aproduction of around 400 kton a year. The new algorithm is shown to increase the crushing stagethroughput with 6.9 per cent. The FSM algorithm, on the other hand, increases the throughput with5.3 per cent, which is a confi rmation of the magnitude of its benefi ts demonstrated in an earlierpaper.
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| 3. |
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| 4. |
- Johansson, Robert, 1983, et al.
(författare)
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Circulating Air Classification of Manufactured Sand
- 2010
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Ingår i: XXV INTERNATIONAL MINERAL PROCESSING CONGRESS 2010 PROCEEDINGS. - 9781921522284 ; , s. 851-858
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Konferensbidrag (refereegranskat)abstract
- Due to environmental concerns, the supply and use of natural gravel has been limited by the Swedishgovernment. The Swedish concrete industry is therefore examining manufactured sand as analternative that has equal or better product quality, and which the Swedish quarry industry alreadyhas the ability to deliver. However, in order to comply with the specifi cations set by the concreteindustry, a better means of classifi cation is needed, as the proportion of fi ne particles (fi ller) smallerthan 63 - 125 μm in size must be reduced. One classifi cation technology that meets the requirementsmay be air classifi cation. This paper examines the process of circulating air classifi cation, which isnot yet commonly used in the Swedish quarry industry; suggesting that a better understanding of theprocess is needed.The circulating air classifi er in this study has two internal machine parameters that can affect theseparation point; namely, the speeds of the circulating fan and the separator fan. We study theireffect on the separation point as well as the interaction between these parameters.Full-scale parameter tests are also conducted, in which size distribution is measured before andafter the circulating air classifi cation. This study shows how the different parameters affect theseparation point and that it is possible to produce manufactured sand according to specifi cations.Computational fl uid dynamics (CFD, Fluent) is used to study the internal fl ow of the air circulatingwithin the classifi er. A single-phase study of the fl ow fi eld is conducted to support and explain thefi ndings from the full-scale tests.
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| 5. |
- Lee, Elisabeth, 1980, et al.
(författare)
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Validation and Simulation of Optimised Compressive Crushing
- 2010
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Ingår i: XXV INTERNATIONAL MINERAL PROCESSING CONGRESS IMPC 2010. - 9781921522284 ; , s. 943-956
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Konferensbidrag (refereegranskat)abstract
- Ores and aggregates are used in countless applications all around in the society. The frequent and escalating usage of these natural resources requires efforts aimed at not only making do with what is available, but also undertaking actions to improve the production yield and the processes involved. This strive to improve the performance and effi ciency of existing crushers and crushing processes has brought about research concerning optimisation of crushing plants as well as theoretical optimisation of crushing.Previous work shows that different applications and different materials require different compressive crushing in order to accomplish a theoretically optimal size distribution. These optimisation results, obtained by genetic evolutionary algorithms and evaluated with so called fitness functions, convey the theoretically optimal number of compressions and their corresponding compression ratios. Presented in this paper are thus some laboratory crushing tests, which are conducted in order to validate a set of previously optimised crushing sequences. More specifi cally, interparticle crushing sequences are carried out in a Piston-die testing equipment, where samples are sieved between each compression. The subsequent analysis of these results shows good correlation with model predictions, which combined with a comparative study between presented optimisation results and measured data from a real crusher indicate a signifi cant potential for improvement.However, before redesigning crushers according to what is theoretically optimal, the resulting impact as well as the effects on the outcome of a crushing plant must be examined. Crushing plant simulations using the software PlantDesigner® are consequently performed. Models of existing crushers are altered, resulting in changed particle size distributions from some of the crushers ina crushing plant. Thence, it is concluded that signifi cant gains can be made in terms of capacity, process yield and energy consumption.
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| 6. |
- Quist, Johannes, 1985, et al.
(författare)
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Application of discrete element method for simulating feeding conditions and size reduction in cone crushers
- 2010
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Ingår i: XXV International Mineral Processing Congress (IMPC) 2010 Proceedings / Brisbane, QLD, Australia / 6-10 September 2010. - 9781921522284 ; 5, s. 3337-3347
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Konferensbidrag (refereegranskat)abstract
- The objective of this paper is to simulate the effects of segregation of the feed material entering the hopper on top of a typical cone crusher. A commercially available Discrete Element Method (DEM) software has been used to simulate and demonstrate some important aspects and phenomena and problems that are common in cone crushers. The first phenomenon of interest is segregation and uneven distribution of the feed entering a cone crusher. This is a common problem in many applications and leads to decreased comminution performance, poor product quality, uneven wear of the crusher manganese liners, high stress amplitudes and premature fatigue failures. This problem has been observed in many different applications and can sometimes severely affect the crusher performance in a negative way. A range of possible solutions to address the segregated feed is studied. The internal size reduction process occurring in a cone crusher is also modelled an simulated by applying DEM. The results of the simulations show the dynamics of the crusher and the interaction of the rock material and the machine as well as the breakage and the size reduction process of the rock particles. The results from the DEM simulations of the crushing process are confirming earlier results retrieved by analytical models and simulations. The number of compressive crushing zones is confirmed to be around 10-11 in the studied crusher. The capacity of the crusher is controlled by the choke level. The two different breakage modes, inter and single particle, is clearly seen in the simulations. In addition, some new insights in the internal size reduction process are gained.
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| 7. |
- Rao, K Hanumantha, et al.
(författare)
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Flotation of phosphate gangue from magnetite fines - non-ionic surfactant as atrac collector modifier
- 2010
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Ingår i: XXV International Mineral Processing Congress. - Carlton, Vic : The Australian Institute of Mining and Metallurgy. - 9781921522284 ; , s. 1933-1943
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Konferensbidrag (refereegranskat)abstract
- Adsorption, contact angle and flotation of anionic Atrac and non-ionic ethaloxylated nonylphenol surfactant, and their mixture on apatite and magnetite were studied. The effect of calcium ions and sodium silicate on Atrac adsorption was investigated. The effect of Atrac adsorption on the contact angle data of apatite and magnetite in the presence and absence of sodium silicate was also examined. Wettability of solids depends on solids surface free energy and the surface energies of apatite and magnetite powders were calculated from polar and non-polar liquid contact angle data. A decrease in particle size increased the polar contribution to surface free energy due to unsaturated broken bonds on the surface. Atrac is seen to adsorb equally on apatite and magnetite, and the adsorption increased in the presence of calcium ions. The presence of water glass decreased the Atrac contact angle data on magnetite and also the flotation response demonstrating its role as magnetite depressant in flotation. The presence of non-ionic surfactant enhanced the Atrac flotation of apatite with no flotation of magnetite. Bench-scale flotation tests showed that 50 per cent of Atrac can be replaced with non-ionic collector without impairing the flotation results. Results also illustrate that the non-ionic adsorbs on apatite in equal amount of Atrac collector signifying 1:1 composition of anionic and non-ionic collector on apatite surface. Non-ionic head group sitting in between anionic head groups screens the electrostatic repulsion and forms compact adsorbed layer on apatite surface thereby increasing the hydrophobicity and flotation.
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| 8. |
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