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Estimation of particle size distributions in mineral process systems using acoustic techniques
Thesis (MEng)--Stellenbosch University, 2000.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867614134519988224 |
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| access_status_str | Open Access |
| author | Swanepoel, Francois |
| author2 | Weber, D. M. |
| author_browse | Swanepoel, Francois Weber, D. M. |
| author_facet | Weber, D. M. Swanepoel, Francois |
| author_sort | Swanepoel, Francois |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2000. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/51746 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:47:13.037Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/51746 Estimation of particle size distributions in mineral process systems using acoustic techniques Swanepoel, Francois Weber, D. M. Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Ore-dressing Particles Acoustic sensor Mineral process systems Measuring particle size Metallurgical accounting Dissertations -- Electrical engineering Thesis (MEng)--Stellenbosch University, 2000. ENGLISH ABSTRACT: A desire to increase the efficiency of the comminution process in mineral process systems has led to the need of determining the size distribution of ore particles at various stages in the system. The objective of this research is to investigate the feasibility of the use of an acoustic sensor for measuring particle size distribution. The acoustic signal generated when the particles impact on a cantilever bar is analysed using digital signal processing techniques. As rocks fall onto a metal bar, the bar vibrates. The vibrations contain information th a t is extracted to determine the size of particles tha t impacted on the bar. The bar is modelled as a linear system which is excited by impulses (impact of particles). The response of the bar is deconvolved from the acoustic signal to obtain an impulse whose amplitude is proportional to the energy of the impact. In order to improve size estimates, deconvolution is performed using a statistical model of the impulse sequence (Bernoulli-Gaussian) and then estimated using MAP estimation. Size estimates are not only a function of the mass of particles, but also on the exact position of impact on the bar. Since there is always a variation in the position of impact, size estimates are erroneous. It was found that the position of impact can be determined as to reduce variances dramatically. Due to physical sampling in space, the sensor has a bias towards larger particles. We show how this can be represented mathematically and removed. This project is mainly concerned with rocks in the +8-25mm (+0,7-22 gram) size range. AFRIKAANSE OPSOMMING: Vergruising van erts in die mineraalbedryf verg groot hoeveelhede energie. Daar is ’n behoefte gei'dentifiseer orn hierdie proses meer effektief te maak. Aangesien die effektiwiteit van ’n meul ’n funksie is van die ertsgroottes wat gemaal word, kan partikel grootte inligting aangewend word om effektiwiteit te bevorder. Die doel van hierdie tesis is om die lewensvatbaarheid van ’n akoestiese sensor vir die doel van partikelgrootte estimasie, te ondersoek. Erts partikels wat val vanaf ’n vervoerband op ’n kantelbalk, veroorsaak dat die balk vibreer. Deur hierdie vibrasies te meet en verwerk, kan inligting aangaande partikel grootte verkry word. Die stelsel word gemodelleer as ’n lineere sisteem met impulse as intree. Die geobserveerde sein is die konvolusie tussen die intree impulse en die impulsweergawe van die sisteem. Deur gebruik te maak van ’n statistiese model en MAP-estimasie, word die effek van die sisteem gedekonvuleer vanaf die geobserveerde sein om ’n benadering van die intree impuls sein te verkry. Die amplitudes van die impulse word gebruik as ’n aanduiding van partikel massa. Partikelgroottes soos benader deur die stelsel, is ’n funksie van die die posisie waar die partikel die balk tref. Deur van patroonherkenning tegnieke gebruik te maak, word die posisie van impak bepaal om sodoende grootte benaderings aan te pas en die variansie van grootte verspreidings te verminder. As gevolg van die feit dat partikels gemonster word deurdat slegs ’n klein persentasie van die hele omvang van partikels ondersoek word, onstaan daar ’n oorhelling ( “bias” ) na groter partikels. Die kans dat groter partikels die balk tref is groter as vir klein partikels. ’n Wiskundige model vir hierdie verskynsel word voorgestel en gewys hoe die die oorhelling geneutraliseer kan word. Hierdie projek het te doen met ertsgroottes +8-25mm (+0,7-22 gram). 2012-08-27T11:34:40Z 2012-08-27T11:34:40Z 2000-04 Thesis http://hdl.handle.net/10019.1/51746 en_ZA Stellenbosch University 96 p. : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Ore-dressing Particles Acoustic sensor Mineral process systems Measuring particle size Metallurgical accounting Dissertations -- Electrical engineering Swanepoel, Francois Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title | Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title_full | Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title_fullStr | Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title_full_unstemmed | Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title_short | Estimation of particle size distributions in mineral process systems using acoustic techniques |
| title_sort | estimation of particle size distributions in mineral process systems using acoustic techniques |
| topic | Ore-dressing Particles Acoustic sensor Mineral process systems Measuring particle size Metallurgical accounting Dissertations -- Electrical engineering |
| url | http://hdl.handle.net/10019.1/51746 |
| work_keys_str_mv | AT swanepoelfrancois estimationofparticlesizedistributionsinmineralprocesssystemsusingacoustictechniques |