Method for producing a high-purity nanometer zinc oxide from low-grade zinc oxide ore by ammonia decarburization

摘要

Disclosed is a method for producing a nanometer zinc oxide from low-grade zinc oxide ore by ammonia decarburization. The method comprises: taking ammonia water-ammonium bicarbonate solution as a leaching agent; adding 0.3-0.5 kg sodium fluorosilicate to per cubic meter of the leaching agent; leaching low-grade zinc oxide ore with the leaching agent; and adding 50-60 kg slaked lime to per cubic meter of leached solution to carry out decarburization treatment. The obtained nanometer zinc oxide powder has purity of 99.7% or up, uniform particle size distribution (average particle size of 10-28 nm), specific surface area of 107 m2/g or up, good fluidity and good dispersity. The treatment method of the present invention is low in energy consumption and high in efficiency, and the leaching agent can be recycled. The final leached residue subject to the leaching treatment, without destruction of original mineral component phase composition, can still be used for brick making, so as to achieve dual purposes of economy and environment protection, and has a high economic value and social value.

主权项

1. A method for producing a nanometer zinc oxide from low-grade zinc oxide ore by ammonia decarburization, comprising:
the low-grade zinc oxide ore being processed by leaching, purification for impurity removal, crystallization by ammonia evaporation, drying and calcinations, comprising: taking ammonia water-ammonium bicarbonate solution as a leaching agent in said leaching step, wherein said ammonia water-ammonium bicarbonate solution includes the molar concentration c(NH3)=5.5-7 mol/L and the molar concentration c(CO32−)=0.95-1.2 mol/L, and 0.3-0.5 kg sodium fluorosilicate is added to per cubic meter of said leaching agent; adjusting zinc oxide of said leached solution to 50-60 g/L, and then performing heating to reduce ammonia from said ammonia water-ammonium bicarbonate solution and decarburize said ammonia water-ammonium bicarbonate solution by natural precipitation, via the following steps: adding 30-60 kg slaked lime to per cubic meter of said leached solution and stirring said leached solution to produce a stirred solution, heating said stirred solution to 90-98° C. until c(CO32−)≦0.3 mol/L, and c(NH3)≦3.5 mol/L, and then adding ammonium persulfate with the amount of 3-4 kg/m3 and slaked lime powder with the amount of 5-10 kg/m3 to produce a treated solution, stirring to decarburize said treated solution which is then subject to an oxidation reaction, detecting when the concentration of CO32− is ≦0.1 mol/L and removing iron and manganese from said treated solution to produce a new solution, and performing solid-liquid separation on said new solution; performing refining treatment after purification for impurity removal by adding ammonium phosphate and surfactant to said new solution after purification to produce a refined solution, wherein the amount of ammonium phosphate is 1-3 kg per cubic meter of said new solution after purification, and the amount of surfactant is 10-50 g per cubic meter of said new solution after purification.