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Systems Based on Germanium Sulfides
Published in Vasyl Tomashyk, 2 Semiconductors, 2022
According to the data of Hahn and Lorent (1958), Zn2GeS4 was obtained in this system. It crystallizes in the cubic structure of the sphalerite type with lattice parameter a = 543.6 pm and the calculated and experimental densities of 3.427 and 3.26 g⋅cm−3, respectively. This compound was obtained by the heating of 2ZnS + GeS2 mixture at 500°C–700°C, but later its existence was not confirmed (Kaldis et al. 1967; Dubrovin et al. 1989b). The ingots were annealed at 750°C and 790°C for 100 and 80 h, respectively (Dubrovin et al. 1989b). Ternary compounds in the Ge–Zn–S system were not found (Kaldis et al. 1967).
Minerals of base metals
Published in Francis P. Gudyanga, Minerals in Africa, 2020
Sphalerite (Zn, Fe)S is the major commercial source of zinc metal [715]. Other sources of zinc are smithsonite (zinc carbonate), hemimorphite (zinc silicate), wurtzite (another zinc sulphide), and sometimes hydrozincate (basic zinc carbonate). Sphalerite consists largely of zinc sulphide with variable amounts of iron. Associated with it are minerals galena PbS, pyrite FeS2 and other sulphides as well as calcite CaCO3, dolomite CaMg(CO3)2, and fluorite CaF2. As a chalcophile, zinc has low affinity for oxides and prefers to bond with sulphides.
Crystal Structure
Published in Alan Owens, Semiconductor Radiation Detectors, 2019
Zincblende. Named after the mineral zinc blende or “sphalerite”, which is the principal ore of zinc. In fact it consists largely of crystalline ZnS. The zincblende structure is the stable form of many III-V and II-VI compounds and is structurally identical to that of diamond described previously, except that alternate atoms are respectively from Group III and of Group V for III-V materials and Groups II and VI for II-VI materials (see Fig. 3.9). Among the materials that classify into this structure are virtually all of the Group III-V compounds (e.g., GaAs, InAs, InSb and InP).
Kinetic models of zinc dissolution from artificial sphalerite with different iron contents in oxygen pressure leaching
Published in Canadian Metallurgical Quarterly, 2020
L. Tian, X. Q. Yu, A. Gong, X. G. Wu, T. A. Zhang, Y. Liu, Z. F. Xu
Sphalerite, in which Zn exists predominantly in the form of ZnS or nZnS·mFeS, is extensively used as a raw material for the conventional roast-leach-electrowin (RLE) method of zinc production [1]. However, the similarity in the electrochemical properties of Zn and Fe leads to the formation of isomorphous materials in the sphalerite ore [2]. Zinc ferrite is evolved during roasting due to the interaction of Zn and Fe; thus, it is difficult to recover the Zn2+ leached from the ore [3]. Furthermore, the SO2 generated during the process is harmful to the environment. Pressure leaching is considered as a promising revolution in the metallurgical and chemical industries [4–7] because it results in reduced pollution and higher recycling ratios for Zn, S, and other metals [8–10]. Furthermore, in contrast to the conventional RLE method, iron is a catalyst in the pressure leaching process, and this contributes to the rate of reaction. But it is found that in the process of pressure leaching of sphalerite, it is not better to have more iron ions, and the increase of iron ions will produce a large amount of ferrite residue after the reaction, which is not conducive to normal industrial production [11–14].
An approach to measuring and modelling the residence time distribution of cement clinker in vertical roller mills
Published in Mineral Processing and Extractive Metallurgy, 2022
Kianoush Barani, M. R. Azadi, Rasoul Fatahi
The RTD measurement was carried out by an impulse test using zinc concentrate powder. The main zinc mineral in the concentrate was sphalerite (ZnS). Table 1 shows the chemical analysis of the concentrate. As the raw materials of the VRM are zinc free then zinc can be analysed as a tracer in the VRM product by a traditional analytical method such as atomic absorption spectrometry (AAS). The zinc powder was pelletised with cement and some water (Figure 2). The pelletised tracer was provided in such a way that its size distribution and strength was similar to the VRM feed. However, their breakage behaviour is not quite similar; this does not matter because the tracer mixed with the mill content and contaminated the feed particles, and all particles in the mill played the role of the tracer. Figure 3 shows the particle size distribution of the tracer pelletised with cement and the VRM feed. The tracer pellets are mixed with the mill content and contaminates the feed particles where all particles in the mill can play the role of tracer. The weight of the tracer pellets was sufficient that after dilution and mixing with the mill content, the Zn concentration can be detected at the VRM product. 100 kg of the pellets was injected in one stage in the feed stream of mill. The mill outlet is a duct in which the ground product sucked at high speed by an air separator. Sampling from this duct is a difficult task. To facilitate sampling, a sampler was designed and manufactured (see Figure 4). The sampler was a steel tube with the length of 1.2 m (width of the duct) and diameter of 40 mm. A hole was embedded in the duct. Every 10–20 s the sampler was entered the duct for two seconds to take one sample. During sampling, the sampler was moved perpendicular to the material flow and the entire width of the outlet duct was sampled. There was a slot (115 mm) at the end of the tube where the particles trapped and fell into the end due to the gravity. In total, 24 samples were taken, and analysed for zinc using AAS (Agilent, 240FS AA model).