| About 72%nickel resource in the world exists as in nickel laterite ore,and nickel laterite ore will be exploited wildly in the future for its advantages of huge resource,low cost of exploration and mining,etc.The technology of atmospheric tank leaching,autoclave leaching,and column leaching for Philippines' nickel laterite ore were developed in this dissertation.The detailed process mineralogy for laterite limonite and saprolite was studied.The process mineralogy results showed that the valuable metal of nickel and cobalt were mainly existed in limonite for limonite type laterite,but it was complex for saprolite.The thermodynamics and kinetics of atmospheric leaching and autoclave leaching for nickel laterite ore were studied.The thermodynamics results showed that the decomposition of minerals was primarily impacted by temperature and acid concentration in the acid leaching process.Lower temperature and acid concentration would lead to lower nickel mineral carrier decomposition ratio.The kinetics results showed that the saprolite leaching was under chemical reaction control,while the limonite leaching was under diffusion control.The atmospheric leaching,column leaching and autoclave leaching process were studied.The extraction of nickel and cobalt were merely 55.78%and 62.32%under the conditions of 650 kg acid/t-ore,95?reaction temperature,4h residence time for limonite atmospheric tank leaching.For saprolite atmospheric tank leaching,the extraction of nickel and cobalt reached 86%and 92%under the conditions of 600 kg acid/t-ore,95 ? reaction temperature,4h residence time.The results of saprolite column leaching showed that the nickel extraction ratio reached 81%after 57 days column leaching,and the acid consumption were 512kg/t-ore.The nickel extraction ratio and acid consumption in column leaching process were closed to the atmospheric leaching process.The results of autoclave leaching for limonite showed that the nickel and cobalt extraction reached 97.28%and 96.10%under the conditions of 260 kg/t-ore acid consumption,245 ?eaction temperature,3.3-3.5 MPa autoclave pressure and 60 mins residence time.The Fe removal by SO2/O2 catalytic oxidation for pregnant solution was studied.The results showed that reaction kinetics of SO2/O2 catalytic oxidized Fe2+ were closed to first-order reaction.Higher Fe2+ concentration leaded to faster reaction rate,and it was conformed to the model of free radical catalytic oxidation mechanism.Two-stage precipitation of nickel and cobalt from the purified solution was studied.The result showed that the recovery of nickel and cobalt were 99.5%and 98.57%after two-stage precipitation. |
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