Selective nickel-iron separation from atmospheric leach liquor of a lateritic nickel ore using the para-goethite method

The presence of iron in pregnant leach solutions (PLS) is a common problem, and is generally removed using jarosite, goethite, hematite or para-goethite precipitation methods. Although these methods are successfully applied, significant amounts of nickel can be lost. In this study, iron precipitation was performed on a PLS obtained from agitation leaching of a lateritic nickel ore under atmospheric conditions using the para-goethite method. The PLS contained 2.62 g/dm3 Ni, 54.28 g/dm3 Fe and 0.14 g/dm3 Co. During the precipitation tests the effect of pH, time, temperature, and metal concentration were investigated. The influence of the key points, temperature and metal concentration, on nickel loss was explained in reference to SEM and XRD analyses. Ultimately, selective nickel and iron separation was achieved with complete iron precipitation and only 1.2% Ni loss

Separation of nickel and iron from lateritic ore using a digestion – roasting – leaching – precipitation process

This paper investigates extraction of nickel and iron from a lateritic nickel ore from the Caldag region of Manisa in Turkey. The ore sample contains 1.2% Ni, 24.77% Fe and 0.062% Co. The process applied includes digestion with 40 wt-% sulfuric acid at 200 C for 60 min, roasting at 700 C for 15 min, leaching with water for 30 min at 1:5 solid/liquid ratio (by weight) and precipitation of the remaining iron at pH 3 and 60 C. In order to improve nickel and cobalt extractions using the digestion-roasting- leaching-precipitation process (DRLP), Na2SO4 addition in the roasting stage was examined. Under the optimum conditions and in the presence of Na2SO4, 86.2% Ni and 94.2% Co extractions were obtained with almost zero iron content. As a result, 2.07 g dm-3 Ni, 0.12 g dm-3 Co and 0.05 g dm-3 Fe could be achieved in the pregnant leach solution within nearly 2.5 hours

Leaching behaviour of a turkish lateritic ore in the presence of additives

This paper investigates the dissolution mechanism of a lateritic nickel ore from the Caldag Region of Manisa in Turkey. The ore sample contained 1.2% Ni, 24.8% Fe, and 0.062% Co. The optimum leaching conditions were found to be temperature 80 oC, particle size -74 μm, H2SO4 concentration 200 g/dm3, solids ratio (by weight) 10% and leaching duration 8 h. The extractions of 98.2% Ni, 98.6% Fe and Co 98.9% were obtained under these conditions. Additionally, the effects of additional substances such as NaCl, Na2S2O5, Na2SO4, and KCl were investigated in order to decrease the leaching duration. The results showed that the additives accelerated the leaching kinetics and achieved nearly the same nickel and cobalt extractions at the end of 4 h compared to the results obtained after 8 h without the additives. If the additives containing chlorine were used, it was determined that the iron extraction showed no increase, although both the nickel and cobalt extractions increased

The influence of pre-aeration on cyanide leaching of a non-refractory sulphide gold and silver ore

The leaching behaviour of a sulphide gold-silver ore was investigated in terms of a relationship between gold and silver extractions and cyanide consumption. Ninity five Au % and 88.0% Ag extractions were obtained under the determined conditions of 24 h leaching duration, -74 μm particle size, 40% solids ratio, 4 g/dm3 NaCN concentration, and 450 rpm stirring speed with NaCN consumption of 3.35 g/dm3. Since the NaCN consumption was higher than in industrial applications, Pb(NO3)2 and H2O2 additions and aeration using an air pump were tested during leaching in order to decrease the consumption. While Pb(NO3)2 addition with aeration caused a decrease in the metal extractions, the individual or combined additions of H2O2 and aeration could not provide a reduction in the cyanide consumption. Therefore, the effect of the pre-aeration followed by cyanidation was tested. Eventually, applying 4 h of pre-aeration before a shorter leaching duration of 12 h provided 92.0% Au and 90.5% Ag extractions with a reduced NaCN consumption of 2.44 g/dm3