Sulfur, lead, and mercury in South Africa coals: existential form of the elements, isotope, and emissions from the coal fired-power plants

Coal-fired power plants (CFPPs) are the dominant source of electricity in South Africa due to natural abundance of coal in the country. However, emission of SO2, Pb, and Hg has raised serious environmental and public health concerns. Hence, to reduce emissions and utilize coal efficiently, estimating emission trend, understanding the forms of elemental occurrence in coals, and affinities to minerals, organic matter, and pyrite, are essential. Therefore, this paper aimed to assess the forms of elemental occurrence of sulfur, and Pb and Hg affinities to ash and sulfur, in the coals via statistical correlation and their isotopic compositions. This study also estimated SO2, Pb, and Hg emissions from 1971 to 2018 from the CFPPs on levels of activity and emission factors. Based on the results, South Africa coals mostly comprise equivalent fractions of organic and pyritic sulfur. The Pb were correlated with ash (R2 = 0.393), which is an indication of the presence of bound clay mineral. However, the highest Pb208/Pb206 and the lowest Pb208/Pb206 in South Africa coals which contain high inertinite (organic matter) and low sulfur, reveal organically associated Pb. Similarly, clay minerals associated Hg appeared based on its relationship with ash (R2 = 0.450), and the remaining could be an organic matter related. As an organic matter associated element least cleanability and readily oxidizing nature, burning South Africa coals containing a substantial quantity of organic sulfur and organically bound Pb and Hg without washing will obviously result to higher emissions. The estimated for SO2, Pb, and Hg emissions were 355.84 Gg, 168.91 tons, and 4.84 tons in 1971, and increased to 1468.13 Gg, 696.89 tons, and 19.95 tons in 2018, respectively. The values approximately increased by a factor of 4.

Study on the New Technique for High-Sulfur Lead-Zinc Ore of Laos

This study presents sulfide ores with lead 0.71%, Zinc5.07% from Laos, using a grinding (grinding fineness -0.075mm, 80%). Then, the lead ores is recovered by flotation first. Second, the middling ores is returned in preferential floatation. The mixed collector is used in all flotation such as ethyl xanthogenate , butyl xanthate and SN-9.After flotation, the grade of lead concentrate is 63.63%, and a recovery is 83.26% .In addition, the grade of zinc is 56.33%,a recovery is 86.63%. It can result in obvious increase in yields of mineral processing and economic better effect in production, compared to the old technology.

Mutually reactive elements in a glass host matrix: Ag and S ion implantation in silica

Ag, S, Ag + S, and S + Ag single and double ion implantations in silica glass were performed at room temperature. The implantation energies were chosen in order to get a projected range of 40 nm. The fluences were 2 × 1016 S+ cm−2 and 5 × 1016 Ag+ cm−2. Silver interacts weakly with the host silica matrix and forms essentially metallic clusters; this weak interaction between Ag and SiO2 induces formation of silver silicate rather than silver oxide. Double ion implantations of silver and sulfur lead to chemical interaction between the two species that is critically influenced by the implantation sequence. In particular, in the Ag + S sample silver and sulfur atoms react to form crystalline core (Ag)–shell (Ag2S) nanoclusters.