Research In Disposal And Resource Utilization Of Phosphated Residue

Phosphating technology has become more and more widely used for surface treatment. Phosphated residue, which is produced by the surface disposal,is a kind of solid waste that pollute the environment badly. Many studies have been made to reclaim and utilize the phosphated residue effectively, but the characters of system, economy and utility still cannot meet practical demands. Therefore, the research on the disposal and the utilization of phosphated residue is significant. In this paper, a study has been made on searching for an effective method of using phosphated residue as resources from dissepiment electroanalysis treatment , being changed into a new kind of composite phosphate solution and composite anti corrosive pigment.(1) Dissepiment electroanalysis treatmentIn the Electroanalysis experiments, a dissepiment is devised between the pole cathode and phosphated residue solution to isolate the solution in pole cathode and phosphated residue solution. The result of experiment shows that the Mn²⁺ can be released and move into pole cathode effectively.As the electrify time goes on ,the Mn²⁺ concentration has changed unconspicuous,Seven hours is the best time of electroanalysis. The concentration grads which is brought by electromigration in electrobath also exists in stasis solution.Dissepiment electroanalysis treatment is suitable for disposing phosphated residue which has more metal element,and it needs being researched deeply.(2) Being changed into a new kind of composite phosphate solutionA new kind of composite phosphating solution has been setted up by using zinc phosphate residue. The additives and technics parameter of phosphating are influencing factors of the corrosion resistance of phosphating coat ,which has been studied by electrochemical technology, immersion test,EIS,SEM and so on. According to the result of orthogonal experiments , the optimum composition for the composite phosphating solution were determined as follows: basic phosphating solution 0.2 L/L, zinc oxide 5 g/L, sodium carbonate 9 g/L, nitric acid 12.5 mL/L, concentrated phosphoric acid 2.5 mL/L,copper sulphate 0.3 g/L, additive B 2 g/L,additive A 3 g/L,trisodium citrate dihydrate 1.5g/L.The composite phosphating solution is a light green transparent solution with pH 2～3, TA 18.0～20.0,and FA 1.0～1.5.The phosphating temperature is 60～70℃and phosphating time is 300-600s. Then it has been used in the phosphating treatment of A3 steel sample to form phosphate coating. The result of experiment shows that the phosphate coating, whose microstructure is a short-rod, has good physical properties and corrosion resistance.This technology is simple and apt to operate, which has little pollution. So this is a kind of more ideal resource utilization technology, and it has very vast of applied foreground.(3) Being changed into composite anti corrosive pigmentHow to make the transition of the wastes into composite anti-corrosive pigment has been researched. According to the result of analysing the phosphating residue composition, a technical method on producing composite anti corrosive pigment has been discovered. The results of testing experiments on composite anti-corrosive pigment shows that the density, the oil adsorption and the water-soluble materials of the product are 3.303 g/m³,27.9% and 0.151% respectively. Its particle size dissolution shows an abnormal distribution and the particles coagulate takes on the shape of bricks. The results of XRF and XRD revealed that the main ingredients of the production paint are ZnOand Fe₂O₃. The experiment of immersion test shows that the composite anti corrosive pigment has heightened the resistance of dope.