ORIGINAL PAPER
Selective flocculation and recovery of chrome from plant slimes using starch and sodium oleate as flocculants
 
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1
University of the Witwatersrand
 
2
Botswana International University of Science and Technology
 
 
Submission date: 2022-05-09
 
 
Final revision date: 2022-10-12
 
 
Acceptance date: 2022-10-26
 
 
Publication date: 2022-12-20
 
 
Corresponding author
Tirivaviri Auguatine Mamvura   

Botswana International University of Science and Technology
 
 
Gospodarka Surowcami Mineralnymi – Mineral Resources Management 2022;38(4):205–230
 
KEYWORDS
TOPICS
ABSTRACT
A steady global decline in the grade of chromite ores is causing an increase in the mining of low grade and complex ores. The processing of such low grade and finely disseminated ores results in the increased production of primary and secondary slimes. Slimes have very poor recovery performance in most conventional technology and are usually disposed of into tailings storage facilities (TSF). The historic slimes in the TSFs and those arising from most chrome production processes constitute potential recoverable chrome resources. In this study, the selective flocculation of slimes from a chrome processing plant in the north west province of South Africa was conducted using raw corn starch and sodium oleate as flocculants and sodium silicate a dispersant was applied on. Limited work has been reported on the flocculation of non-synthetic chrome slimes. The results showed that a slime sample with a chrome (Cr2O3) head grade of 22.92% was upgraded to a maximum concentrate grade of 42.55% at a sodium oleate dosage of 88 g/tonslurry, a sodium silicate dosage of 44 g/tonslurry, 39.61% at a starch dosage of 106 g/tonslurry and sodium silicate dosage of 62 g/tonslurry. The corresponding recoveries using sodium oleate as a flocculent were between 80–89% and 73–79% for starch. Sodium oleate showed a better performance than starch in terms of both grade and recovery. Decantation washing tests showed that the chrome (Cr2O3) grade of the concentrate can be further increased to above 44%. These results are very encouraging as they indicate that selective flocculation can achieve satisfactory upgrade ratios and recovery when processing chrome ultrafine or slime material.
ACKNOWLEDGEMENTS
The authors would like to acknowledge the chrome processing plant in the North-West province of South Africa for providing the chrome ore slimes for this investigation. The authors would also like to acknowledge the School of Chemical and Metallurgical Engineering at the University of Witwatersrand, South Africa for the provision of the reagents, laboratory equipment and the funding for the investigation.
METADATA IN OTHER LANGUAGES:
Polish
Selektywna flokulacja i odzyskiwanie chromu ze szlamów zakładów przemysłowych przy użyciu skrobi i oleinianu sodu jako flokulantów
flokulacja selektywna, szlam chromowy, flokulant, dyspergator, odzysk, gatunek
Stały spadek jakości rud chromitowych na całym świecie powoduje wzrost wydobycia rud niskogatunkowych i wielosurowcowych. Przeróbka tak niskogatunkowych i drobnouziarnionych rud powoduje wzrost ilości szlamów pierwotnych i wtórnych. Szlam ma bardzo słabą wydajność odzysku w większości konwencjonalnych technologii i jest zwykle umieszczany w osadnikach odpadów przeróbczych (TSF – Tailings Storage Facilities). Historyczne szlamy w TSF i te powstające w większości procesów produkcji chromu stanowią potencjalne zasoby chromu do odzyskania. W pracy przeprowadzono selektywną flokulację szlamów z zakładu przetwórstwa chromu w północno-zachodniej prowincji RPA, stosując surową skrobię kukurydzianą i oleinian sodu jako flokulanty oraz krzemian sodu jako dyspergator. Odnotowano ograniczoną liczbę prac nad flokulacją niesyntetycznych szlamów chromowych. Wyniki wykazały, że próbka szlamu o zawartości chromu (Cr2O3) 22,92% została ulepszona do maksymalnego poziomu koncentratu 42,55% przy dawce oleinianu sodu 88 g/tonę szlamów i krzemianu sodu 44 g/tonę szlamów i 39,61% przy dawce skrobi 106 g/tonę szlamów i krzemianu sodu 62 g/tonę szlamów. Odpowiednie odzyski przy użyciu oleinianu sodu jako flokulanta wynosiły od 80–89% do 73–79% dla skrobi. Oleinian sodu wykazał lepsze wyniki niż skrobia zarówno pod względem jakości, jak i odzysku. Testy płukania dekantacyjnego wykazały, że odzysk chromu koncentratu (Cr2O3) można dodatkowo zwiększyć do ponad 44%. Wyniki te są bardzo zachęcające, ponieważ wskazują, że selektywna flokulacja może osiągnąć zadowalające wskaźniki poprawy i odzysku podczas przetwarzania ultradrobnego lub szlamowego materiału chromowego.
 
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