TW346419B - Process for recycling collected dust in an arc furnace stainless steel factory - Google Patents

Abstract

A process for recycling collected dust in an arc furnace stainless steel factory, which comprises: (a) mixing the collected dust with water to form a slurry; (b) feeding the slurry into a flotation tank, adding a capturing agent; (c) continuously mixing the mixture while introducing air in thereby generating a large quantity of air bubbles; (d) filtering the floating mineral and the precipitated mineral thereby obtaining a refined mineral and a tail mineral; (e) feeding the refined mineral into a dissolution tank and adding water into the tank, slowly adding hydrochloric acid into the tank adjusting the pH of the mixture to 0~1, while heating the mixture to 70℃~80℃, adding a small quantity of hydrogen peroxide, after through reactions carrying out a vacuum filtration separation thereby obtaining two matters: one being a mixture solution of zinc chloride, and the other being a non acid soluble chromite refined mineral; (f) feeding the chromite refined mineral into a mixing tank, washing the mineral with water, followed by a dehydration treatment, until the pH of the mixture reaching 5~6 drying the mixture into a chromite refined mineral; (g) feeding the zinc chloride mixture solution into a dissolution tank, while under mixing heating the solution to 70℃~80℃, adding a small quantity of hydrogen peroxide, after through reactions adjusting the pH of the solution to 5.0 by using a pure alkali, carrying out a vacuum filtration separation thereby obtaining two matters: one being a mother liquid of zinc chloride, and the other being a mixture residue of ferric oxide; (h) feeding the mother liquid of zinc chloride into a dissolution tank, while under mixing adding a zinc powder, heating the mixture to 80℃~100℃, after reacting for about one hour, carrying out a vacuum filtration separation thereby obtaining two matters: one being a mother liquid of zinc chloride, and the other being a mixture residue of nickel; (I) feeding the mother liquid of zinc chloride into a dissolution tank, while under mixing slowly adding a pure alkali to adjust the pH of the mixture to 7.5~8, carrying out a vacuum filtration separation thereby obtaining two matters: one being a zinc carbonate residue, and the other being an aqueous solution of sodium chloride; (j) washing the zinc carbonate residue with water to remove the chlorine ions, after dehydration mixing the mixture with sulfuric acid to dissolve the mixture, after cooling the crystals formed being ZnSO4.7H2O, or converting the ZnSO4.7H2O into ZnSO4.1H2O by high temperature vacuum concentrating.