The Effects of Oxidative Pretreatment of Zinc-containing Dust on Contents of Iron and Manganese in Ammoniacal Leaching Solution and Product ion of Zinc Oxide

The zinc-containing dust was oxidatively pretreated with calcium hypochlorite,subsequently leached with ammonia/ammonium bicarbonate solution to obtain the ammoniacal leaching solution,and zinc oxide was produced by ammonia distillation of the ammoniacal leaching solution and subsequent calcination. The elements of iron and manganese could not be detected in ammoniacal leaching solution,and the extraction rate of zinc was 98.2% in ammoniacal leaching process. The zinc oxide content in the product is 99.5%(ω),and the contents of iron and manganese in the product were 0.002 8‰ and 0.000 84‰(ω), respectively. The analyses of the valence states of iron and manganese in the zinc-containing dust with and without pretreatment were performed by chemical analysis and XPS,and the possible oxidation mechanism of the oxidative pretreatment of the dust was discussed. It is concluded that Fe 2+-oxide and Mn 2+-oxide in the dust were oxidized to Fe 3+-oxide and/or its hydrate and Mn 4+-oxide and/or its hydrate by calcium hypochlorite during the oxidative pretreatment process,respectively.

Zinc-containing chainlike polymer {Cs_2[Zn(S_2C=C(CN)_2)_2]}_n,the second example of bridging [S_2C=C(CN)_2]

The title compound {Cs2[Zn(S2C=C(CN)2)2]}n(2),Catena-poly {dicesium [bis(l,l-dicyanoethene-2,2-dithiolato-S,S':N)-Zinc(Ⅱ)]},is the second example of bridging [S2C=C(CN)2] (hereafter referred to as i-mnt) for metal-containing polymer.It crystallizes in the non-centrosymmetric space group Ia (alt.Cc,No.9).There are two coordination modes of i-mnt in this compound:μ-η1-η1-i-mnt,bridging two Zn moieties with two S atoms and terminal i-mnt.A characteristic feature of the structure is the infinite-Zn(η2-i-mnt)(η1-η1-i-mnt)-Zn(η1-η1-i-mnt)(η2-i-mnt)-wave-like chain.Cs atoms are located between the chains to form three-dimensional network-like packing.An efficient second harmonic generation from the crystal has been observed on the irradiation with the 1064 nm output of a Nd:YAG laser.

Corrosion mechanism of magnesia-chromite refractories by ZnO-containing fayalite slags: Effect of funnel glass addition

An efficient approach for lead extraction from waste funnel glass through the lead smelting process has been proposed. To clarify the effect of funnel glass addition on the degradation of magnesia-chromite refractories by ZnO-containing fayalite slag, the corrosion behavior of magnesia-chromite refractories in lead smelting slags with different funnel glass additions from 0wt% to 40wt% was tested. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) was used to acquire the microstructural information of the worn refractory samples. Experimental results showed that the corrosion of magnesia-chromite refractory consisted predominantly of the dissolution of MgO into slag. ZnO and FeO reacted with periclase and chromite to form (Zn,Fe,Mg)O solid solution and (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel, respectively. With the addition of funnel glass, the solubility of MgO increased whereas ZnO levels remained stable, thereby resulting in a reduced Mg content and an elevated Zn and Fe content in the (Zn,Fe,Mg)O solid solution and the (Zn,Fe,Mg)(Fe,Al,Cr)2O4 spinel. Considering the stability of the (Zn,Fe,Mg)O solid solution layer and the penetration depth of the slag, the optimal funnel glass addition for lead smelting was found to be 20wt%.

Synergistic reaction behavior of pyrolysis and reduction of briquette prepared by weakly caking coal and metallurgical dust

Co-carbonization of weakly caking coal and zinc-containing dust to prepare highly reactive ferro-coke and collaboratively recover zinc powder is one of the feasible ways for steel enterprises to recycle zinc-containing dust.The pyrolysis mass loss behavior of adding blast furnace dust with different zinc contents to different ferro-coke materials was systematically studied by thermogravimetry and differential thermogravimetry analysis,and the kinetic mechanism of pyrolysis-reduction reaction of hybrid briquette was explored.The results of thermogravimetric curve analysis show that the addition of zinc oxide to the sample has no significant effect on the mass loss rate of the sample below 580℃,and the pyrolysis mass loss of zinc oxide mainly occurs between 800 and 1000℃.Kinetic analysis results show that the pyrolysis of zinc-containing samples is controlled by chemical reactions below 580℃.The reaction at 580–700℃ is controlled by the nucleation and growth model,and that above 700℃ is mainly controlled by diffusion.The results of X-ray diffraction analysis show that the pyrolysis process can effectively remove zinc oxide from ferro-coke.