| This paper stands of comprehensive utilization of magnesium and nickel of serpentine with nickel. By taking the serpentine of Fujian with the concentration of nickel 0.22%, and with the concentration of magnesium oxide 37.4% as the research object, on the base of analysis of chemical elements and phase analysis, a process of treating the serpentine with nickel by leaching with strong acid was established. By systematic test to the leaching in constant pressure and pressure leaching with sulpuric acid and hydrochloric acid, a new technical route of pressure leaching with sulpuric acid and process conditons was determined; the nickel sulfide and magnesium oxide with high quality and high recovery was gotten and the comprehensive utilization of the resources of nickel and magnesium of serpentine with nickel was realized.Optimal process conditions of serpentine with nickel by leaching in constant pressure with sulfuric acid and hydrochloric acid respectively was explored by single factor test. In optimal process conditions of sulfuric acid leaching in constant pressure, the leaching recovery of nickel and magnesium only reaches 50.7% and 61.1% respectively, and the leaching recovery of both is low. In optimal process conditions of hydrochloric acid leaching in constant pressure, the leaching recovery of nickel and magnesium can reach 93.6% and 82.2% respectively, but the reaction can't be controlled easily and the hydrochloric acid losses much in high temperature.The optimal process conditions of hydrochloric acid pressure leaching are as follow:the serpentine with the particle size under 0.074mm occupies 74.5%, the acid-solid ratio is 1.25, the reaction time is 60min, the reaction temperature is 110℃, the stirring speed is 500rpm, the liquid-solid ratio is 4, and in those conditions the leaching recovery of nickel and magnesium reaches 96.1% and 85.1% respectively. The nickel sulfide and magnesium oxide was prepared in leaching solution by removing iron, sinking nickel with sulfide, sinking magnesium with hydroxide and calcining hydroxide. The concentraion of nickel reaches 6.28% and the total recovery of nickel reaches 73.6%; the concentration of magnesium oxide reaches 95% and the total recovery reaches 70.0%. The economic estimation showed that the cost of hydrochloric acid in pressure leaching is little high and it will not be a effective way to recover the nickel and magnesium from serpentine with nickel.The optimal process conditions of sulfuric acid pressure leaching are as follow:the serpentine with the particle size under 0.074mm occupies 74.5%, the acid-solid ratio is 0.6, the reaction time is 120min, the reaction temperature is between 110℃and 120℃, the stirring speed is 500rpm, the liquid-solid ratio is 4, and in those conditions the leaching recovery of nickel and magnesium reaches 96.1% and 85.1% respectively. The leaching solution was removed iron by combining carphosiderite and natrojarosite and the iron removal effieiency reaches 93.2%. Nickel was sunk with sodium sulfide with the concentration of nickel 7.8% and the total recovery of nickel can reach 81.7%. Magnesium was sunk with sodium hydroxide with the recovery 96.5% and the total recovery of magnesium can reach 75.5%. Magnesium hydroxide was calcinated at 800℃in 60min; the concentration of MgO reaches 97.1% and the main product and impurites content accords with requirements of superior product of HG/T2573-94. The results of experiments and economic estimation showed that the sulfuric acid pressure leaching treating serpentine with nikcel has some advantages such as little corrosion to equipments, low energy consumpting, recycled wastewater circulative utilization of wastewater, good quality of products et al. The sulfuric acid pressure leaching is a prospective process to recover nickel and magnesium from serpentine with nickel comprehensively... |
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