To recover zinc from electric arc furnace(EAF)dust,a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed.First,under the alkaline pressure leaching system,the experiment of...To recover zinc from electric arc furnace(EAF)dust,a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed.First,under the alkaline pressure leaching system,the experiment of pure zinc ferrite being reduced by iron powder was carried out.Under the optimal reduction conditions(i.e.,temperature of 260℃,NaOH concentration of 6 mol/L,liquid-to-solid ratio of 50 mL/g,and a 5-fold excess of iron powder),89%of zinc was extracted.The iron in the reduced residue exists as a magnetite phase.Subsequently,the normal pressure leaching experiment was carried out with EAF dust as raw material,and 66%zinc was leached.The main phase of zinc in normal leaching residue was determined to be zinc ferrite.Then,the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system,and 66.5%of zinc was extracted.After the two-stage leaching process,the leaching rate of zinc in EAF dust can achieve 88.7%.The alkaline pressure leaching solution can be returned as the normal pressure leaching solution,and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.展开更多
为了研究氯化钠对蔗糖粉尘的抑爆作用,采用1.2 L Hartmann测试装置对氯化钠蔗糖混合粉尘的最小点火能进行测试,研究了氯化钠浓度及粒径对蔗糖粉尘云最小点火能的影响。结果表明:添加了氯化钠后,蔗糖粉尘着火敏感度降低,最小点火能显著提...为了研究氯化钠对蔗糖粉尘的抑爆作用,采用1.2 L Hartmann测试装置对氯化钠蔗糖混合粉尘的最小点火能进行测试,研究了氯化钠浓度及粒径对蔗糖粉尘云最小点火能的影响。结果表明:添加了氯化钠后,蔗糖粉尘着火敏感度降低,最小点火能显著提升;氯化钠浓度越高,粒径越小,抑爆效果越好;粒径小于75μm的氯化钠质量分数达40%可使混合粉尘的最小点火能大于1000 mJ,粒径大于75μm的氯化钠质量分数需达到70%才能使混合粉尘的最小点火能大于1000 mJ;对不同浓度的蔗糖粉尘,燃烧被完全抑制时所需氯化钠的质量分数也不同,蔗糖粉尘浓度越高时,氯化钠对蔗糖粉尘燃烧的抑制效果越差,氯化钠在混合粉尘中所占比例需更高才能使燃烧被完全抑制;氯化钠粉末在蔗糖粉尘燃烧的过程中主要起到物理抑制作用,包括改变初始湍流、屏蔽热辐射、阻碍热传导及影响粉尘云的均匀程度。展开更多
This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO...This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.展开更多
基金Project(51504292)supported by National Natural Science Foundation of ChinaProject(2018JJ3678)supported by the Natural Science Foundation of Hunan Province,China。
文摘To recover zinc from electric arc furnace(EAF)dust,a process of primary normal pressure leaching and secondary alkaline pressure leaching is proposed.First,under the alkaline pressure leaching system,the experiment of pure zinc ferrite being reduced by iron powder was carried out.Under the optimal reduction conditions(i.e.,temperature of 260℃,NaOH concentration of 6 mol/L,liquid-to-solid ratio of 50 mL/g,and a 5-fold excess of iron powder),89%of zinc was extracted.The iron in the reduced residue exists as a magnetite phase.Subsequently,the normal pressure leaching experiment was carried out with EAF dust as raw material,and 66%zinc was leached.The main phase of zinc in normal leaching residue was determined to be zinc ferrite.Then,the normal leaching residue was reduced by iron powder under the alkaline pressure leaching system,and 66.5%of zinc was extracted.After the two-stage leaching process,the leaching rate of zinc in EAF dust can achieve 88.7%.The alkaline pressure leaching solution can be returned as the normal pressure leaching solution,and the magnetite in the alkaline pressure leaching residue can be recovered by magnetic separation.
文摘为了研究氯化钠对蔗糖粉尘的抑爆作用,采用1.2 L Hartmann测试装置对氯化钠蔗糖混合粉尘的最小点火能进行测试,研究了氯化钠浓度及粒径对蔗糖粉尘云最小点火能的影响。结果表明:添加了氯化钠后,蔗糖粉尘着火敏感度降低,最小点火能显著提升;氯化钠浓度越高,粒径越小,抑爆效果越好;粒径小于75μm的氯化钠质量分数达40%可使混合粉尘的最小点火能大于1000 mJ,粒径大于75μm的氯化钠质量分数需达到70%才能使混合粉尘的最小点火能大于1000 mJ;对不同浓度的蔗糖粉尘,燃烧被完全抑制时所需氯化钠的质量分数也不同,蔗糖粉尘浓度越高时,氯化钠对蔗糖粉尘燃烧的抑制效果越差,氯化钠在混合粉尘中所占比例需更高才能使燃烧被完全抑制;氯化钠粉末在蔗糖粉尘燃烧的过程中主要起到物理抑制作用,包括改变初始湍流、屏蔽热辐射、阻碍热传导及影响粉尘云的均匀程度。
文摘This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.
