Recovery Of Nickel From Leaching Residue Of Nickel-Molybdenum Ore

Leaching residue of nickel-molybdenum ore, the waste of molybdenum extraction process from nickel-molybdenum ore, contains nickel and other valuable metals, and therefore can be used for recovering nickel. This paper describes the process of nickel recovery from leaching residue of nickel-molybdenum ore.Thermodynamic analyses suggest that nickel can be recovered using an ammonium sulfate roasting-water leaching process. Within the temperature range of this experiment, ammonium sulfate reacts not only with nickel, but also with impurities such as Fe, Ca, Zn, Al, etc.The following experimental parameters were optimized for the roasting-water leaching process by single factor experiment and orthogonal experiment:Dosage coefficient of ammonium sulfate (1.75), roasting temperature (600°C), roasting time (5h), liquid-solid ratio (10), leaching temperature (95°C), and leaching time (2h). Under optimal conditions, the extraction rate of nickel reached80%, compared with less than4%for iron.To increase the extraction rate of nickel, the effects of additives on nickel and iron leaching were investigated. Under conditions of ammonium sulfate dosage coefficient1.75, potassium sulfate dosage50%, roasting temperature550°C,roasting time3h, liquid-solid ratio10, leaching temperature95°C and leaching time1.5h, the extraction rate for nickel was elevated to98.29%, in contrast to less than2%for iron.Fluoride precipitation was adopted to eliminate calcium (Ca2+) and magnesium (Mg2+) cations, and solvent extraction was applied to remove iron, aluminum and zinc from leach liquor. Suitable conditions were defined for removing Ca2+and Mg2+:beginning pH value3.5, dosage coefficient of NaF1.5and reaction time1h. This elimination step reduced Ca2+and Mg2+levels to less than2.4mg/L and7.8mg/L respectively.Under conditions of P204concentration (v/v)30%, saponification rate of P20470%, Vo/VA0.25, extraction time7min, the concentrations of Fe3+, Al3+and Zn2+in the purified nickel solution declined to2.5mg/L5.6mg/L and1.2mg/L, respectively.Enrichment of nickel from purified nickel solution by P204extraction was studied, and proper conditions were determined (beginning pH value3.98, P204concentration (v/v)30%, Vo/VA0.2, saponification rate of P20430%and extraction time1min), under which the extraction rate of nickel was further enhanced to99.26%. Additionally, suitable conditions for the stripping process were also obtained:concentration of sulphuric acid100g/L, Vo/VA5, stripping time7min. A single-stage stripping rate of99.6%was achieved based on these conditions.