A Preliminary Study Of The Recycling Of Biological Oxidation Solution In The Gold Mineral Process

Presently in the field of practical engineering, the harmless treatment of biological oxidation solution has been frequently applied in the gold mineral process, while such valuable elements with relatively high content as As、Fe have rarely been recycled. The recycling of As and Fe can not only bring benefits to the enterprises, but also can reduce the environmental pollution, which is a win-win situation in terms of economy and environment benefits. This thesis studies on gold refining biological oxidation solution of a certain Jiangxi gold deposit, and it aims to study the effectiveness of coprecipitation and alkaline leaching on the isolation of Fe and As.This thesis uses Na2S as its selective arsonium, on the other hand, we study such technological parameters as Na2S’s amount, pH, reaction time, and temperature’s influence on the separation of As and Fe. At the same time, we choose NaOH as the coprecipitation dose, studying these technological parameters’impacts, for instance, PH, temperature, stiring intensity and reaction time, on the coprecipitation of As and Fe, so as to get the appropriate processing condition. In order to guarantee the standard of effluent, we adjust coprecipitation supernate’s pH to remove the heavy metals. Under the condition of boiling and ultrasound lixiviate, we use NaOH as the lixivia to achieve the isolation of Fe and As and study the influence of such conditions as alkali concentration、the volume of alkali solute on the isolation of Fe and As. Thus we finally get the optimum technological conditions of the isolation of Fe and As.The followings are the main conclusion of this thesis:(1) With the method of sulfidization in selectively sinking As, the rate can reach at least92%under these conductions, that is to say, pH=0.8, S/As=2.50, room temperature and20minutes’reaction time. However, the residual As in the oxidation solution still live up to the discharging standard, so it needs further process. Meanwhile, the surplus sulfion makes it more difficult to dispose oxidation solution in the latter steps.(2) The optimum technological conditions of the isolation of Fe and As from the experiment of coprecipitation in the biological oxidation solution:pH is5, agitation speed is500r/min, room temperature and reaction time is30minutes. Under this condition, the content of As and Fe that we get from supernatant is less than sewage discharge standard(0.5mg/L), and attain the effective isolation of Fe and As. When we adjust coprecipitation supernate’s pH to the level of9, all of the heavy metal ions are below the sewage discharge standard.(3) When separating As and Fe in the sediment with the alkali leaching, Boil’s effect is better than ultrasound. In boiling solution with the alkali leaching, when adding2mol/L NaOH(10mL)into the0.4kg/kg sediment, the extraction ratio of As is77%, in which way the alkali consumption and the extraction ratio reach the optimum state. In using ultrasound with the alkali leaching, when adding2mol/LNaOH(12mL)into the0.48kg/kg sediment, the extraction ratio of As is81%, in this way the alkali consumption and the extraction effect reach the optimal state.(4) It costs171to186kg/m3NaOH occupying48%to separate As from Fe in the recycled biological oxidation solution with the conbinatin of coprecipitation and alkaline leaching, with a ralatively high consumption of alkali, namely,171to225yuan/m3. Eventually, we can get Fe(OH)3and NaAsO4, respectively weighing351kg/m3and148kg/m3.