Hydrothermal precipitation

In the hydrometallurgical industry, Fe solutions are often produced as waste products and hydrothermal methods are being investigated as a possible route for their disposal by production of hematite of saleable quality (Riveros and Dutrizac, 1997). 

---

Ejaz, T. 1997. Hydrothermal precipitation of zeolite A crystals. PhD Thesis, University of London, UK. 

Other methods including hydrothermal precipitation, flame hydrolysis, thermal decomposition of Fe(CO)s and high temperature reaction of Fe " chloride with iron, are used only on a small scale to obtain specialty products (see Chap. 19). 

Robins, R.G. (1967) Hydrothermal precipitation in solutions of thorium nitrate, ferric nitrate, and aluminium nitrate. J. inorg. nud. Chem. 29 431-435... 

Metz, S. and Trefry, J.H. (1993) Field and laboratory studies of metal uptake and release by hydrothermal precipitates. Journal of Geophysical Research, 98(B6), 9661-666. 

Russell, M.J., Daniel, R.M., Hall, A.J., and Sherringham, J.A. 1994. A hydrothermically precipitated catalytic iron sulfide membrane as a first step toward life. J. Mol. Evol. 39 231-243. 

E. P. Stambaugh and J. F. Miller, "Hydrothermal Precipitation of High Quality Inorganic Oxides," in S. Somiya, ed., Proceedings of First International Symposium on Hydrothermal Eeactions, Gakujutsu Bunken Fukyu-kai (c/o Tokyo Institute of Technology), Tokyo, Japan, 1983, pp. 859—872. 

Third, the degree of crystallinity or extent of disorder should be evaluated, whether due to (a) mode or conditions of formation, for example, low temperature as opposed to hydrothermal precipitation, or (b) techniques employed to prepare the sample for Investigation, such as mechanical grinding. These factors tend to increase the solubility and make the material less stable than an ordered macroscopically crystalline sample. 

Assimilation of near-surface material that has low-temperature-induced disequilibrium is a spectre frequently raised in the discussion of U-series disequilibria in MORBs. For example, ferromanganese coatings and hydrothermal precipitates on seafloor samples sequester significant amounts of unsupported °Th, and Pa... 

Polster W. (1994) Hydrothermal precipitation and dissolution of silica Part I. Conditions in geothermal fields and sedimentary basins Part 2. Experimental evaluation of kinetics. PhD, Pennsylvania State University. 

Trefry J. H. and Metz S. (1989) Role of hydrothermal precipitates in the geochemical cycling of vanadium. Nature 342, 531-533. 

Major components of marine pelagic sediments are aluminosilicates (shale), manganese oxides, CFA, zeolites, biogenic carbonates, silica, and barite. Volcanic ash, hydrothermal precipitates, and rare continental detritus minerals at times become additional important components. The elements shown to associate with manganese... 

Hydrothermal precipitation— hydrodiermal crystallization Hydrothermal decomposition... 

One of the industrial applications of hydrothermal precipitation is ordinary alumina production. The Bayer process is shown in Figine 1.7. T... 

Seafloor hydrothermal systems that are reasonably well studied in terms of stable isotope values of fluids, hydrothermal precipitates and hydrothermal alteration are presented as case studies in this section. Ranges of sulfur isotope values from given deposits are summarized in Figure 11. It is clear that most of the mid-ocean ridge sulfides (designated S SmbS to indicate metal sulfide minerals), ) us those from Manus and Mariana back-arc spreading centers, are quite similar with ranges of about l-5%o. 

Herzig, P.M., Hannington, M.D. and Arribas, A.(jr.)., 1998. Sulfur isotopic composition of hydrothermal precipitates from the Lau back-arc implications for magmatic contributions to seafloor hydrothermal systems. Mineralium Deposita, 33 226-237. 

Hydrothermal precipitation at relatively high temperatures (400 °C) and under pressure allows the direct synthesis of a-Al203 powders by adjusting the reaction conditions, nanosized particles of corundum can be obtained (40). 

Powders synthesized by hydrothermal synthesis are crystallized phases, so that the calcination step is not required, which is different from the normal solution precipitation. The powders also have very fine particle/grain size (10-100 nm), narrow size distribution, single crystal particles, high purity, and good chemical homogeneity. However, the application of hydrothermal precipitation to synthesize transparent ceramic powders is still not very popular, which deserves further exploration. Several examples are presented as follows [188-192]. 

On the Origin of Life in the Zinc World 1. Photosynthesizing, Porous Edifices Built of Hydrothermally Precipitated Zinc Sulfide as Cradles of Life on Earth... 

Figure 9. Hydrothermal precipitation of cobalt powder c.f. text for detail precipitation conditions).

The use of hydrothermal precipitation with iron to remove oxyanions such as those of arsenic, antimony, vanadium and titanium, particularly ferric arsenate has been proposed (Swash Monhemius 1995, 1996). This disposal option is based on geochemical considerations in that these minerals are stable, for example over 60% of arsenic minerals are arsenates of which... 

---