Studies On The Technology Of Ammonia Leaching-Extraction-Electrolyzing Zinc For Blast Furnace Ashes

A large amount of containing zinc dusts were produced during iron and steel production.The dusts returning to the sintering process as sintering raw material will affect the permeability of sintering material layer,at the same time zinc accumulation in the process of ironmaking,easily produces the nodules on the upper of blast furnace and reduces the service life of blast furnace.At present,there are many methods of fire technology?such as rotary hearth furnace process and rotary kiln method?of processing zinc dust in our country,but the existence of large investment,high energy consumption in these technologies greatly limit their popularization and application.Therefore,according to the selective leaching principle of hydrometallurgy,low zinc ashes treated by using ammonia leaching-extraction of leaching liquid-electrolytic zinc process was proposed,and this not only obtained the comprehensive utilization of resources,and achieved the purpose of energy conservation and emissions reduction.The leaching of ammonia-ammonium chloride solution for Blast furnace ashes containing low Zn content from a company are studied.And the test results showed that,Blast furnace ashes were leached under the conditions of 5 mol·L^-1 leaching agent of ammonia and ammonium chloride,liquid-solid ratio of 6:1,leaching time of 3 h,agitation speed of 360 r·min^-1 and leaching temperature of 35 ?,and leaching ratio of zinc was as high as 84.89%.The effects of various factors on the zinc extraction of P204 extraction solvent from containing zinc NH₃-NH₄Cl solution were investigated.And the obtained optimum conditions of zinc extraction were: the volume fraction of P204 was 25%,the diluents was sulfonated kerosene,extraction time was 40 min,extraction compared to 1/1,the initial pH was 7.5,extraction temperature was 35 ?,the mass fraction of sulfuric acid solution when back extracting was 10%.Under these extraction conditions,extraction ratio of zinc stabilized at 95.52% above.Zinc extraction ratios of 3 counter-current extraction and 3 cross-flow are 99.59% and 99.78% respectively,which was higher than zinc extraction ratio of single first-order extraction.And the obtained optimum process conditions for Zn back extraction were as follow: the mass fraction of sulfuric acid solution was 30%,water phase volume of reverse extraction was 15 mL,and extraction temperature was 35 ?.And reverse extraction was carried out under these conditions,and concentration enrichment of zinc could achieve maximum.And blast furnace ash ammonia-leaching solution choosed P204 as extractant and selected sulphuricacid system as back extraction agent which are appropriate,because P204 extraction solvent recycling use frequency was high,the back extraction effect of zinc enrichment was better.The tests of electrodeposited zinc of the back extraction water phase were carried out.And their results showed that,the effect of electrolyzing zinc was best under the conditions of current density of 800 A·m^-2,polar distance of 1.8 cm,the electrolyte pH of 1.0,electrolytic temperature of 50 ?,additive content of 0.05 g·L^-1,electrolyte initial concentration of 27.39 g·L^-1,and current efficiency was the best.