A green process for recovering nickel from nickeliferous laterite ores

A novel process was proposed for recovering nickel from nickeliferous laterite ores.First of all,silicon and magnesium were removed from lateritic ore by high concentration sodium hydroxide leaching and carbonation respectively,so as to enrich nickel. Then the method of ammonia carbonate leaching was adopted to recover nickel from the carbonized slag,and the remaining residue was used as a raw material for recovering iron.The effects of temperature,ammonia carbonate concentration,liquid/solid ratio and stirring speed on the recovery of nickel were examined.When the leached residue reacted with ammonia carbonate(6 mol·L- 1)in a ratio of liquid-to-solid of 5-1 at 60℃for 150 min at the stirring speed of 300 r·min- 1,approximate more than 95%nickel was recovered.During the whole process,there was no contamination produced and the chemical raw materials were recycled,thus the process was a green technology that having good social benefit.

Mineralogical Investigation and Washability Treatment of the Nickeliferous Lateritic Deposit of Nome (Albania)

The Nome nickel laterite deposit is located in the North East of Albania. The ore deposit, developed between ultramafic rocks and limestones during Early Cretaceous to Eocene, represents part of the Albanian Mirdita ophiolite zone. The lateritization of the deposit was observed mainly in three separate areas, the Has-Kukes-Lure in the North, Pogradec-Librazhd in the center and Devoll in the South. The main mineralogical components of the ore are goethite, hematite and quartz, while the secondary ones are chlorite (clinochlore, Ni-chlorite), kaolinite and lizardite. Nickel is mainly found in chlorite. The ore is characterized by the presence of spheroid particles, such as oval, pisoid, peloid and composite spheroid. According to the microscopical examination the ore is characterized in general as allotriomorphic, inequigranular and the texture is oolitic-pisolitic. For the mineral processing gravimetric and magnetic separation are used in the size fractions &#458 + 4 mm, &#454 + 1 mm, &#451 + 0.250 mm and &#450.250 + 0.063 mm. The chemical and mineralogical analyses, as well as the microscopic examination have shown that mineral processing by magnetic separation gives the most satisfactory results for the size fractions &#451 + 0.250 mm and &#450.250 + 0.063 mm.

Quality Characteristics and Washability Treatment of Nickeliferous Iron Ore of Agios Athanasios Deposit (Kastoria, Greece)

The Agios Athanasios ore deposit is located within the wider area of Ieropigi in Kastoria, Greece. The specific ore deposit is developed in form of layers between ophiolites and Tertiary molassic conglomerates. The main mineralogical components are hematite, goethite, quartz, and secondarily, garnierite, lizardite, saponite, willemzeite and sepiolite, while scarcers are chromite, calcite and nepouite. Nickel is mainly found in garnierite, willemzeite and nepouite, which in coexistence with quartz are the main components in the binder material of the ore. For the mineral processing gravimetric and magnetic separations are used in the size of fractions -8 + 4 mm, -4 + 1 mm, -1 + 0.250 mm and -0.250 + 0.063 mm. The chemical and mineralogical analysis in combination with microscopic examination showed that mineral processing by gravimetric separation gave the most satisfactory results for the size fraction -1 + 0.250 mm.

Microbial leaching of chromite overburden from Sukinda mines,Orissa,India using Aspergillus niger

Leaching of nickel and cobalt from two physical grades （S1, 125-190 μm, coarser and S3, 53-75 μm, finer） of chromite overburden was achieved by treating the overburden （2% pulp density） with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600℃ and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction （XRD）, thermogravimetry-differential thermal analysis （DT- TGA）, and field emission scanning electron microscopy （FESEM）. About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.