Thesis (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The objective of this work was to achieve a completely automated fire assay system
for the analysis of process control samples on a flotation plant in less than 120
minutes. With this in mind, a systems engineering approach was undertaken. The
physical and chemical characteristics of the technology for each subsystem were
investigated in turn and the critical factors that influenced accuracy, precision and
analysis time were identified and optimised.
Some of the key developments achieved during this work were:
· Existing technology for the sampling, filtering, drying and grinding of flotation
plant samples were evaluated and where necessary, modified for this
application.
· The fusion system was totally re-designed with a bottom-loading configuration
called FIFA (Fast In-line Fire Assay) to make automation with a central robot
possible. With the fast fusing flux developed, a quantitative collection of the
platinum group elements with a fifteen-minute fusion was achieved compared to
an hour for the classical method.
· A robust automated separator system was developed to isolate the lead
collector from the fusion in the molten state thereby separating it quantitatively
from the slag. This allowed the automation of the entire fire assay process.
· Methods to prepare lead standards for calibration were developed. These were
used to optimise analytical protocols for the analysis of platinum group elements
in lead using a spark optical emission spectrometer. This made it possible to
accurately determine the quantities of platinum group elements in lead samples
prepared by the automated fire assay system.
· A fully automated system was developed that could meet the accuracy and
precision requirements for the analysis of tailings and feed grade samples in
concentrator slurry streams in less than one hour compared with the 24-72
hours required when using classical methods.
The new fire assay technology including flux, FIFA system, oxygen lance and
separator were all patented along with the automation vendor. This technology has
made the first fully automated fire assay system a reality. / AFRIKAANSE OPSOMMING: Die hoofoogmerk van die studie was om ‘n totale geoutomatiseerde vuuressaieering
stelsel te ontwerp vir die ontleding van prosesbeheermonsters van ‘n flotasieaanleg in
‘n bestek van 120 minute. Gedurende die ontwerp is ‘n ingeneursstelselbenadering
gebruik. Die fisiese en chemiese kenmerke van elke deel van die tegnologie is eers
afsonderlik en dan as ‘n geheel ondersoek. Die bepalende faktore wat akkuraatheid,
presisie en ontledingstyd beinvloed het was geidentifiseer en geoptimeer.
Die hoofpunte van die werk behels onder andere die volgende:
· Bestaande tegnologie vir monsterneming, filtrasie, droging en vermaling van
flotasiemonsters was ondersoek en is, waar nodig, aangepas vir die finale
stelsel.
· Die smeltingsisteem was in geheel herontwerp om monsters van onder in die
FIFA (Fast In-line Fire Assay) sisteem te laai en sodoende die outomatisering
met ‘n sentrale robot te vergemaklik. ‘n Vinnig smeltende vloeimiddel was
ontwikkel wat ‘n kwantitatiewe versameling van die platinum groep elemente
binne ‘n tydsduur van vyftien minute moontlik gemaak het, in vergelyke met die
oorspronklike duur van die klassieke smelt metode van een uur.
· ‘n Outomatiese skeier was ontwikkel waarmee die gesmelte loodversamelaar
geskei kon word van die slakfase. Met die nuwe stelsel kon die hele
vuuressaieerproses outomaties verloop.
· Metodes is ontwikkel om loodstandaarde vir kalibrasie doeleindes te berei. Die
standaarde is op hulle beurt weer gebruik om ‘n ontleding protokol daar te stel
vir die analiese van die platinum groep elemente in lood, met behulp van ‘n
vonkontlading-optiese-uitstraling-spektrometriese instrument. Ten einde was dit
moontlik om outomaties klein hoeveelhede van die platinum groep elemente in
monsters akkuraat te bepaal, na voorbereiding met behulp van die
geoutomatiseerde vuuressaieering stelsel.
· Die volle geoutimatiseerde stelsel was ontwikkel wat aan die akkurate en
noukeurige vereistes voldoen het vir die ontleding van flotasie-uitskot-envoergraad
monsters van die konsentraataanleg binne die bestek van ‘n uur.
Die nuwe vuuressaieer tegnologie, insluitend die vinnig smeltende vloeimiddel, FIFA
en skeier stelsels, asook die suurstof lanset is gepatenteer met die vervaardiger. Die
studie het gelei tot die eerste volle geoutomatiseerde vuuressaieering stelsel wat tans
gebruik word in die industrie.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/16062 |
| Date | 12 1900 |
| Creators | McIntosh, Keith Shearer |
| Contributors | Eksteen, J. J., Lorenzen, L., Koch, K. R., University of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | xxv, 269 leaves : ill. |
| Rights | University of Stellenbosch |
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