Study On Wastewater Treatment Technique Of Conghua Ta/Nb Metallurgy Plant

A large amount of industrial wastewater will be produced from Ta/Nb metallurgy process. This type of wastewater contains high contents of NH₄⁺,F^- and SO₄^2-. How to recover ammonia or ammonium salts and reduce the concentration of these polluted materials from the Ta/Nb metallurgy wastewater to realize the wastewater comprehensive treatment is significant both in theory and practical use. The aim of this research is to solve the treatment technique of the wastewater from the Conghua Ta/Nb Metallurgy Plant. Based on theory analysis and experiment investigation, the selection of the treatment methods, evaluation of treatment effects and design of treatment techniques were carried out. The following results have been obtained:(1) The best blowing conditions to take off ammoniate nitrogen from the Ta/Nb metallurgy plant wastewater have been suggested. The experiment shows the stripping efficient of ammoniate nitrogen can reach 97% with 2 hours blowing under the conditions of 10.5 -11 of pH value and 30-50°C of temperature.(2) The treatment technique of CaO precipitation-distillation- ammonia recovery was investigated. The experiment has indicated that this combination technique can effectively reduce ammoniate nitrogen concentration to less than 15mg/L by twice treatments to reach the discharge standard, and get a 70% recovery of ammonia from the wastewater.(3) The treatment technique of magnesium phosphate deposition - zeolite adsorption was investigated. The experiment has indicated the magnesium phosphate deposition has reduced the ammoniate nitrogen concentration from 12800mg/L to 200mg/L and the natural zeolite adsorption treated the residual ammoniate nitrogen to 14.7mg/L to reach the discharge standard.(4) Three kinds of combination treatment techniques for the Conghua Ta/Nb Metallurgy Plant wastewater were discussed. The technique of deposition-alkaline evaporation - biological degradation- RO membrane was suggested. This technique can reuse the ammonia from the wastewater to achieve zero discharge, and callback the investment in 3—4 years.This results can be not only applied to the wastewater treatment of the Conghua Ta/Nb Metallurgy Plant, but also provide an important reference to wastewater treatment of other types of metallurgy plants.