By Ida <sup>. Alkaline 2 - </ Sup>-glu <sup> 2 - </ Sup>-h <sub> 2 </ Sub> O System To Handle Low-grade Zinc Oxide Ore,

Nowadays,with the depletion of zinc sulphide ores which are easily upgraded by floatation,low grade zinc oxide ores difficult to be upgraded and smelt, draw more and more attentions.In this paper the alkaline Ida2-Glu2-H2O system (a mixed complexation system of iminodiacetate and sodium glutamate solution) was used to leach zinc oxide ore with low grade of zinc and high content of gangue,which can effectively prevent the unfavorable influence of alkaline gangue on zinc oxide ore.The basic contents and results were shown as follows:The pH-potentiometric method was employed to determine the protonation constants of iminodiacetic ion and glutamate ion,the successive stability constants of iminodiacetic ion and zinc ion as well as that of glutamate ion and zinc ion under the condition ofⅠ=0.1 and different temperatures of 25℃,40℃,55℃,70℃respectively.Furthermore the stability constant 1gKZnIdaGlu in the mixed complexation system of iminodiacetate and sodium glutamate are also studied by previous method.The technique conditions of oxidate zinc ore leached by alkaline Ida2-Glu2-H2O system were studied,and correspondingly optimum experimental conditions are gained as follows:when the liquid to solid ratio being 5:1,concentration of iminodiacetic acid and sodium glutamate being 0.7mol·L-1 and 0.4mol·L-1 respectively,pH value of 9,leaching time of 2h under 85℃, nearly 72.1% zinc was leached into solution from oxide ore with a low zinc grade of 7.72%,and the concentration of zinc was 9.42g·L-1 In the leaching solution.Leaching solution was purified to remove impurities with zinc power displacement.When the purification process followed the condition of 60min at ambient temperature in the presence of 3g·L-1 zinc power,the concentrations of Cd, Pb in the solution were 0.3mg·L-1 and 2mg·L-1.The technique conditions of extracting zinc form purified leaching solution were studied. Sodium zincophosphate was obtained by direct precipitation with 2ml phosphate adding into purified leaching solution under 25℃for 60min and the precipitation ratio can reach to 96.6%.If NaOH was used to adjust pH,zinc can be precipitated as oxide zinc from leaching solution.And the precipitation ratio can reach to 90.6% under the condition of 80℃,pH of 12.5 for 60 min.CaO was used to adjust pH,mother solution after zinc-precipitation can return to oxide zinc leaching process after precipitating calcium as calcium carbonate by carbon dioxide.