From Dust Containing Germanium Leaching Extraction Of Germanium

It is rich in natural resource of zinc oxide and lead oxide ore in Guizhou Province, which contains a little of germanium and silver. There are 210 thousand tons of available metals only in Zhazichang Mine. A fuming process is adopt for enriching of low-grade lead-zinc oxide ore to produce germanium oxide dust which contains Zn 35-45%,Pb 22-28%,Ge 350-500g/t.That is important raw material to recover germanium. An investigation of leaching process of germanium dust and separating germanium from zinc in the solution by extraction has been made for further making use of the resourceA mass of research has been made on the technics of leaching process of germanium recent year oversea and at home. The research of kinetics of leaching germanium is correspond less. Some universities and smeltery have researched on the aspect of thermodynamics and kinetics to leaching process of coal, dust, slag and ore.The leaching process of germanium dust is studied in this work. According to the analysis chart of x-ray diffraction and chemical phase, it was found that Zinc and lead exist mostly in oxide minerals. Germanium exists mainly in germanium dioxide, less in germinate in the dust. Under acidic condition, the fraction of infusible germanium, which exists in tetragonal system, accounts for 9.88% of the total germanium. Thermodynamics analysis and kinetics research to leaching process of the dust are carried through. The technological condition to separate germanium from zinc in the lixivium by TOA and its mechanism are also carried through.This work is laboratory test. An investigation of leaching process of the dust and extracting process are carried by method of metallurgical physical chemistry. The research plan is:leaching of the dust(for separating zinc and germanium from lead and silver)——extracting of germanium by TOA(for separating germanium from zinc). Leached residue is raw material to extract lead and silver. The work studies the affect on leaching process of temperature, leaching time, stirring speed, solid to liquid ratio and acid concentration. And it also studies kinetics to leaching process of zinc oxide and germanium dioxide. Based on the experiments, the favorable conditions were reaction temperature of 363K, leaching time of 2.5h, stirring speed of 120r/min., solid to liquid ratio of 1/8, and acid concentration of 120g/L. Under these conditions, the leaching and recovery rate of germanium should be more than 87%. It should be improved by increasing the concentration of sulfuric acid and temperature. Meanwhile, Zinc was dissolved into liquor, and lead and silver stayed in the residue, which made them easily to be separated.optimum conditions of germanium extractions have been investigated from the leaching solutions of germanium dust by using a kind of extractant TOA, complexing agent C4H6O6and improving reagent C12H27O4P, in addition to kerosene as diluent and NaOH as stripping agent. The results show that this process has the following advantages:simplicity in flowsheet, good selectivity, high recovery and availability of the reagents. Through one step extraction and one step back wash extraction, germanium extraction rate is more than 97%. In the process it is hardly extraction of zinc. Separating coefficient to germanium and zinc is estimated. Stripping rate is more than 95%. It is convenient for the sake of recovering zinc and germanium.Germanium exists in state of H2GeO3 in the weak acid. Because of its small dissociation constant k1=1×10-9, k2=3.98×10-23, So there are low concentration of HGeO3- and GeO32-.germanium extracts into organic pHase in ion state. If it is extracted by TOA, germanium extraction rate is very low. When appending complexing agent C4H6O6, it can form anion with germanium which possess big dissociation degree. The reaction is as follow:3C4H6O6+H2GeO3=Ge(C4H4O6)32-+2H++3H2O Extractant TOA is first changed into amine salt. The reaction is as follow:[CH3(CH2)7]3N(O)+H2SO 4(A)=[CH3(CH 2)7]3NH 2SO 4(O)The extraction reaction is as follow:2[CH3(CH2)7]3NH2SO4+H2Ge(C4H4O6)3 ={[CH3(CH2)7]3NH}2·[Ge(C4H4O6)3](O)+2H2SO4(A)The stripping reaction is as follow:2{[CH3(CH2)7]3NH}·[Ge(C4H406)3](O)+2NaOH = Na2[Ge(C4H4O6)3](A)+2H2O(A)+2[CH3(CH2)7]3N(O)The optimum extraction conditions are TOA 30%, improving reagent 5%, diluent 65%. O/A=1/8, mass ratio of complexing agent to germanium 12-16, and at normal temperature,3-5 min.The optimum back extraction conditions are NaOH concentration 30%, O/A=2, and at normal temperature,3-5 min.The extraction compound is determined by infrared spectrum analysis and equal molar method. As a result some conclusions can be gotten. (1) TOA extracting germanium belongs to anion exchange mechanism. (2) The action of TBP is for preventing to form the third pHase in extraction process. and it is still in favor of extracting germanium. (3) The molar ratio of germanium complexing anion and extractant is 1:2. The extraction compound is{[CH3(CH2)7]3NH}2·[Ge(C4H4O6)3](O).