Investigating the Hi-G Dryer System on coarse daberas slurry material

Olivier, Warren John Lloyd (2015-03)

Thesis (MScEng)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: Namdeb Diamond Corporation is constantly investigating and investing in technologies to continuously improve performance and productivity. Diamond mining operations have been taking place for more than a hundred years – ever since the first diamond was discovered in 1908. Diamonds are a scarce and finite resource. As current resources are being depleted, the Namdeb exploration team are exploring areas not previously considered feasible. One such resource is the Sendelingsdrift resource, situated about 20 km from Daberas, one of the current Namdeb operations along the Orange River. When an environmental assessment was conducted, it was discovered that the Sendelingsdrift area was environmentally sensitive in terms of constructing a slimes dam, creating difficulties for slurry processing. Thus the Derrick Hi-G Dryer Fines Recovery System was considered as a probable solution; unfortunately it was found that the slurry discharge would be too coarse for this technology. The Hi-G Dryer technology has never been tested with a coarse slurry feed. The Daberas processing plant produces slurry of -3 mm particles, which is very coarse compared to the 75 μm particles with which the Hi-G Dryer system normally operates. Testing was conducted at Daberas by directing the Daberas wet-sizing underflow as feed to the Hi-G Dryer system. The majority of the testing was done under production conditions, which proved to be very difficult. The results of the initial supplier-designed Hi-G Dryer processing system produced an oversize moisture content of 17%, which was better than that which the supplier had claimed but not as good as that which the existing Daberas degrit system produced. After studying the system parameters and optimising certain parameters, a proposed Hi-G Dryer system was recommended for coarser slurries. The new process parameters generated improved results, with an oversize moisture content of 13% – better than the Daberas dewatering system benchmark. The Hi-G screen oversize material also proved to be conveyable and was quantified with oversize yield stress test results. Overall system efficiency was improved after the recommended modifications to the design had been made and a simulation had been conducted to understand the impact of certain parameters on the overall system.

AFRIKAANSE OPSOMMING: Die Namdeb Diamantmaatskappy is voortdurend daarop ingestel om die maatskappy se prestasie en produktiwiteit te verbeter, veral deur in nuwe tegnologie te belê. Daar word sedert die eerste diamant in 1908 gevind is, diamante langs die Oranjerivier ontgin. Diamante is egter 'n skaars en beperkte hulpbron. Namate die hulpbron uitgeput word, word die Namdeb-span genoodsaak om gebiede te ondersoek wat voorheen nie as ekonomies ontginbaar beskou is nie. Die Sendelingsdriftgebied, wat sowat 20 km van Daberas, een van Namdeb se huidige ontginningsgebiede langs die Oranjerivier, geleë is, is so 'n gebied. Tydens die omgewingsevaluering is egter gevind dat die Sendelingsdriftgebied uiters omgewingsensitief is vir die oprigting van 'n slikdam. Dit het aanleiding gegee daartoe dat die Derrick Hi-G Dryer Fines Recovery System as 'n moontlike oplossing vir die probleem oorweeg is. Ongelukkig was die afvoermateriaal te grof vir die Hi-G Dryer-tegnologie. Die Hi-G Dryer-tegnologie is nog nie vantevore met growwe flodder getoets nie. Die Daberas-aanleg lewer flodder van -3 mm-partikels, wat baie growwer is as die 75 μmpartikels waarmee die Hi-G Dryer-stelsel gewoonlik werk. Die stelsel is by die Daberasaanleg getoets deur die stelsel met growwe ondervloei te voer. Die grootste gedeelte van die toetswerk moes onder produksietoestande gedoen word, wat dit baie moeilik gemaak het. Desondanks was die resultate gunstig. Die aanvanklike prosesuitleg het produkvog van 17% opgelewer, wat beter was as wat die verskaffer van die tegnologie verwag het. Dit was egter nie so goed soos die voginhoud wat die bestaande Daberas-stelsel gelewer het nie. Ná optimalisering van die stelsel het die voginhoud tot 13% verbeter – beter as die huidige Daberas-ontwateringstelsel. Die ontwaterde materiaal was ook maklik afvoerbaar. Die algehele doeltreffendheid van die stelsel het verbeter nadat die aanbevole aanpassings aan die ontwerp gemaak is en 'n simulasie gedoen is om die impak van sekere parameters op die stelsel as geheel te verstaan.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/96637
This item appears in the following collections: