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Sulfate direct leaching nickel laterite nickel and cobalt, under the condition of microwave-assisted single factor in the leaching process: time and concentration of sulfuric acid leaching temperature and microwave power on nickel and cobalt leaching rate. Orthogonal factors and levels, is determined based on the test results of single factor derived optimized leaching conditions: microwave power, 600 W; concentration of sulfuric acid, 25% (v / v); leaching time, 1.5 h; temperature, 90 ℃ . Optimum leaching conditions, the effects of the kinetics of the leaching process, the results showed that the leaching process in line with the contraction of the unreacted core model. Through the the Arrhenius empirical formula, different temperature InK-1 / T diagram calculated nickel, cobalt leaching apparent activation energy of 43.0 kJ / mol and 87.7 kJ / mol, respectively. The leaching process is controlled by the internal diffusion of nickel leaching process is controlled by the surface chemical reaction, cobalt, cobalt leaching is more difficult, slower leaching rate. While increasing the rate of leaching of nickel and cobalt, which is the main content of this research. Microwave power, 600 W; sulfuric acid concentration of 25% (v / v); leaching time, 60 min; under the conditions of temperature, 90 ℃, nickel, cobalt leaching rate was 82.7% and 39.7%. Different type of oxidation and reduction additives leaching process to improve nickel, cobalt leaching rate,: (NH 4 ) 2 S 2 O 8 , Ca (ClO) 2 , H 2 C 2 O 4 , CuCl, NaNO 2 , Na 2 S 2 O 3 , effects of additives on the leaching of nickel, cobalt the impact of the rate. The results showed that in the microwave power of 600 W; sulfuric acid concentration of 25% (v / v); leaching time, 60 min; temperature under 90 ° C conditions, adding of NaNO 2 after the leaching reaction min after cobalt up to leaching balance, the leaching rate of 85.2%, 60 min, nickel up leaching balance, the leaching rate of 90.5%. Na 2 S 2 O 3 , leaching reaction 5 min under the same conditions, the cobalt up to leaching balance, the leaching rate of 70.2% , 60 min, nickel up to leaching balance, the leaching rate of 90.7%. Add the other additives H 2 the C2O 4 CuCl, (the NH 4 ) 2 S 2 O 8 Ca (ClO) 2 , nickel, cobalt leaching rates were 86.7%, 85.5%, 85%, 89.3% and 80.7%, 80.6%, 51.5%, 33.5%. The additives can greatly improve the nickel, and the rate of leaching of cobalt shorter leaching time. The direct microwave assisted sulfuric acid leaching low-grade nickel laterite limonite type, with low power consumption, leaching selectivity, high production efficiency, environmental pollution and other advantages. With the further improvement of this process in the future, will have some role in guiding the progress on China's nickel laterite processing technology as well as industrial applications.
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