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Liquid-Crystal Approaches to Organic Photovoltaics
Published in Sun Sam-Shajing, Sariciftci Niyazi Serdar, Organic Photovoltaics, 2017
Bernard Kippelen, Seunghyup Yoo, Joshua A. Haddock, Benoit Domercq, Stephen Barlow, Britt Minch, Wei Xia, Seth R. Marder, Neal R. Armstrong
Energy needs per person in the world are steadily rising as is the consumption of the fossil fuels that supply us with most of our energy. The world supplies of fossil fuels such as coal, oil, and natural gas are, however, limited and their use to produce energy causes severe environmental problems associated with the emission of carbon dioxide and other harmful greenhouse gases that contribute to global warming. Hence, there is an urgent need to develop new energy sources. Solar energy is potentially an inexpensive continuous source of energy, provided that costs of energy harvesting, storage, and transmission can be lowered to be competitive with other energy sources, the costs of which are generally rising. Research and development in photovoltaics (PV) has grown rapidly during the second half of the 20th century and was enabled by advances made in semiconducting materials. Solar conversion efficiencies well in excess of 10% can be achieved in several materials including silicon, gallium arsenide, indium phosphide, cadmium telluride, copper indium diselenide, and copper(I) sulfide. Today’s PV technology is dominated by Si, a material with low optical absorption, requiring thick high-purity layers with crystalline perfection and high-temperature processing. These limitations keep the cost of crystalline Si technologies high and prevent use on lightweight, flexible substrates. Significant efforts have recently been targeted towards producing cost-effective thin-film (1 μm) amorphous Si, CuIn1−xGaxSe2, and CdTe technologies [1]. These technologies have reached efficiencies <10% (see Figure 11.1), and are entering pilot production. However, the manufacturing, use, and disposal of these materials raise health, safety, and environmental issues.
The Direct Leaching of Nickel Sulfide Flotation Concentrates – A Historic and State-of-the-Art Review Part I: Piloted Processes and Commercial Operations
Published in Mineral Processing and Extractive Metallurgy Review, 2023
Nebeal Faris, Mark I. Pownceby, Warren J. Bruckard, Miao Chen
Despite the successful application of chloride leaching in nickel matte refining, the only chloride-based leaching process developed at scale for processing nickel sulfide concentrates is the HydroNic process developed by Outotec Oyj (Karonen, Tiihonen, and Haavanlammi 2009) and key details of the process are summarized in Table 5. HydroNic employs a two-stage leaching process to dissolve Ni, Co and Cu from base metal sulfide concentrates. In the first stage, nickel is leached from pentlandite by reaction with copper(II) chloride dissolved in a sodium chloride solution recycled from the second leach stage, with Ni and Fe being leached into solution (as their chlorides) whilst copper is precipitated as copper(I) sulfide (Cu2S). This leaching stage is non-oxidative and is a cementation process. In the second stage of leaching, the concentrate is leached under oxidative conditions using oxygen or chlorine gas as the oxidant. Iron is hydrolyzed and precipitated from solution during leaching whilst sulfide in the concentrate is oxidized to elemental sulfur and sulfate. The solution from the second leaching stage is recycled to the first stage to remove copper from solution via cementation as Cu2S. After copper removal, the solution is treated further with caustic (NaOH) and limestone to precipitate iron (as oxyhydroxide) and sulfate (as gypsum) from solution. After iron/sulfate removal, Ni and Co are precipitated from solution as a mixed hydroxide by neutralization with MgO. The patent for the HydroNic process was filed by Outotec Oyj in 2006 (Haavanlammi et al. 2006). Interestingly, another patent was filed by Outotec Oyj in the same year for a chloride leach process for treatment of nickel sulfide ore and concentrates, key differences in this process were the absence of a non-oxidative leaching step, copper(II) was precipitated from the leach liquor as atacamite (Cu2(OH)3Cl) which was returned to the leaching stage and copper recovery after nickel hydroxide precipitation in the form of cuprous hydroxide (CuOH) from which copper metal was recovered via hydrogen reduction (Krebs et al., 2006). The hydronic process has been tested on a range of nickel concentrate grades; however, it does not appear to have been implemented at an industrial scale.