Extraction silicates

The aggregation of the silica species in solution continues upon dilution with water [3], With TPA, the main final products at room temperature are nanoslabs (8), counting 396 Si atoms and composed of twelve precursors (5) (Fig.l). With TPA, it was experienced that the timing of the water addition was not very critical. The yield of Silicalite-1 nanoslabs on silica basis is typically 80% [1]. With TBA, there is a violent hydrolysis and gel formation when the water is added from the beginning. To avoid this, it is preferred to add water after complete hydrolysis. The MEL nanoslabs with occluded TBA rapidly dimerize at room temperature to result in the formation of slabs with dimensions of 1.3 x 4.0 x 8.0 nm [3], The product yield on silica basis is similar to the TPA system. With TEA, the amount of extractable silicate was much smaller. 1R spectra of the extracts recorded after 24 h stirring of the solutions are shown in Fig.3. 

The degree of mesoporosity development in the Fe-Z25 series however appears to be dependent on the concentration of non-framework iron in the zeolite. As the iron loading increases from 0 to 1.1 wt.%, the mesopore surface area upon alkaline treatment progressively decreases from 195 to 115 m g (Fig. 2). Although the mesopore surface areas obtained decrease maximally a factor of 2, remarkably the silicon dissolution is 3 to 7 times lower than in the absence of iron. Similar to alkaline treatment of s-FeS, non-framework iron appears to interact with the extracted silicate species thereby avoiding its dissolution. In the presence of substantial non-framework iron species, further extraction of silicon and additional mesopore formation seems to be hindered. 

Cobalt compounds have been in use for centuries, notably as pigments ( cobalt blue ) in glass and porcelain (a double silicate of cobalt and potassium) the metal itself has been produced on an industrial scale only during the twentieth century. Cobalt is relatively uncommon but widely distributed it occurs biologically in vitamin B12 (a complex of cobalt(III) in which the cobalt is bonded octahedrally to nitrogen atoms and the carbon atom of a CN group). In its ores, it is usually in combination with sulphur or arsenic, and other metals, notably copper and silver, are often present. Extraction is carried out by a process essentially similar to that used for iron, but is complicate because of the need to remove arsenic and other metals. 

The principal ores of zinc are sphalerite (sulfide), smithsonite (carbonate), calamine (silicate), and franklinite (zine, manganese, iron oxide). One method of zinc extraction involves roasting its ores to form the oxide and reducing the oxide with coal or carbon, with subsequent distillation of the metal. 

Hydrogen fluoride Catalyst in some petroleum refining, etching glass, silicate extraction by-product in electrolytic production of aluminum Petroleum, primary metals, aluminum Strong irritant and corrosive action on all body tissue damage to citrus plants, effect on teeth and bones of cattle from eating plants... 

The usual extraction procedure is to roast the crushed ore, or vanadium residue, with NaCl or Na2C03 at 850°C. This produces sodium vanadate, NaV03, which is leached out with water. Acidification with sulfuric acid to pH 2-3 precipitates red cake , a polyvanadate which, on fusing at 700°C, gives a black, technical grade vanadium pentoxide. Reduction is then necessary to obtain the metal, but, since about 80% of vanadium produced is used as an additive to steel, it is usual to effect the reduction in an electric furnace in the presence of iron or iron ore to produce ferrovanadium, which can then be used without further refinement. Carbon was formerly used as the reductant, but it is difficult to avoid the formation of an intractable carbide, and so it has been superseded by aluminium or, more commonly, ferrosilicon (p. 330) in which case lime is also added to remove the silica as a slag of calcium silicate. If pure vanadium metal is required it can... 

Alternatively, as described in U.S. Patent 3,341,557, 6-dehydro-17-methyltestosterone may be used as the starting material. A mixture of 0.4 g of cuprous chloride, 20 ml of 4 M methylmagnesium bromide in ether and 60 ml of redistilled tetrahydrofuran was stirred and cooled in an ice bath during the addition of a mixture of 2.0 g of 6-dehydro-l 7-methyl-testosterone, 60 ml of redistilled tetrahydrofuran and 0.2 g of cuprous chloride. The ice bath was removed and stirring was continued for four hours. Ice and water were then carefully added, the solution acidified with 3N hydrochloric acid and extracted several times with ether. The combined ether extracts were washed with a brine-sodium carbonate solution, brine and then dried over anhydrous magnesium sulfate, filtered and then poured over a 75-g column of magnesium silicate (Florisil) packed wet with hexanes (Skellysolve B). The column was eluted with 250 ml of hexanes, 0.5 liter of 2% acetone, two liters of 4% acetone and 3.5 liters of 6% acetone in hexanes. 

A mixture of iron, ferric chloride and water is added to the toluene solution. The mixture is heated to reflux and concentrated hydrochloric acid is added dropwise at a rate calculated to keep the mixture refluxing vigorously. After the hydrochloric acid Is all added, the refluxing is continued by the application of heat for several hours. A siliceous filter aid is then added to the cooled reaction mixture and the material is removed by filtration. The filter cake is washed four times, each time with 90 ml of benzene. The organic layer is then separated from the filtrate. The water layer is acidified to a pH of 2 and extracted three times with 90 ml portions of benzene. 

The combined extracts were washed with water, dried over anhydrous sodium sulfate and concentrated to approximately 35 ml. The solution was chromatographed over 130 g of Florisil anhydrous magnesium silicate. The column was developed with 260 ml portions of hexanes (Skellysolve B) containing increasing proportions of acetone. There was thus eluted 6a,9a-difluoro-11/3,17a,21 -trihydroxy-16a-methy 1-1,4-pregnadiene-3,20-dione-21 -acetate which was freed of solvent by evaporation of the eluate fractions. 

To 17 C of a culture obtained by submerged fermentation as mentioned above, siliceous earth is added and the batch is filtered. The mixture of mycelium and the siliceous earth are agi-tatedforl hour with 2.5 Cof butanol. This treatment is repeated twice. Thebutanolic extracts are combined, washed with water, evaporated to dry ness (about 10 g) and boiled with acetone (80 ml). The residue (5.41 g of yellowish powder) is distamycin. 

This reaction mixture is kept between 0°C and -i-5°C for six hours, with agitation and under an inert atmosphere, then 5 cc of a 0.2N solution of acetic acid in toluene are added. The mixture is extracted with toluene, and the extracts are washed with water and evaporated to dryness. The residue is taken up in ethyl acetate, and then the solution Is evaporated to dryness in vacuo, yielding a resin which is dissolved in methylene chloride, and the solution passed through a column of 40 g of magnesium silicate. Elution is carried out first with methylene chloride, then with methylene chloride containing 0.5% of acetone, and 0.361 g Is thus recovered of a crude product, which is dissolved in 1.5 cc of isopropyl ether then hot methanol Is added and the mixture left at 0°C for one night. 

Beryllium is extracted from the main source mineral, the alumino-silicate beryl, by conversion to the hydroxide and then through either the fluoride or the chloride to the final metal. If the fluoride is used, it is reduced to beryllium by magnesium by a Kroll-type reaction. The raw metal takes the form of pebble and contains much residual halides and magnesium. With the chloride on the other hand, the pure metal is extracted by electrolysis of a mixture of fused beryllium chloride and sodium chloride. The raw beryllium is now dendritic in character, but still contains residual chloride. 

Insoluble fluorosilicates are brought into solution by fusion with four times the bulk of fusion mixture, and extracting the melt with water. In either case, the solution is treated with a considerable excess of ammonium carbonate, warmed to 40 °C, and, after standing for 12 hours, the precipitated silicic acid is filtered off, and washed with 2 per cent ammonium carbonate solution. The filtrate contains a little silicic acid, which may be removed by shaking with a little freshly precipitated cadmium oxide. The fluoride in the filtrate is determined as described in Section 11.59. 

Pyrocystis lunula (clone T37) can be grown under light-dark cycles as well as under continuous illumination at 20 2°C, in f/2 medium (Guillard and Ryther, 1962) with 0.5% soil extract instead of silicate (Guillard, 1974). The growth is somewhat slower and harvesting may be carried out about 40 days after inoculation, at a cell density of 15,000-20,000 cells/ml. 

The eleetronic configuration of the group-IIA elements, [inert gas] ns, render them so reactive that they never occur native but are always combined with other elements. Thus, Be is found in complex silicate minerals Mg, Ca, Sr and Ba, however, occur in carbonate, sulfate or phosphate ores. Consequently, whereas the extractive metallurgy of Be is relatively complex, that for the other elements is quite straightforward. 

The principal minerals of Be arc listed in Table 1, the most abundant being beryl, the only one of commercial significance. Phcnacitc, chrysoberyl, bertrandite and barylitc arc constituents of recently discovered Be-containing deposits future extraction of Be from these ores is currently being considered. The other minerals are not found in sufficient quantities to constitute possible commercial sources of Be. The majority of the ores, including beryl, are complex silicate materials from which it is difficult to extract the metal consequently. Be extractive metallurgy is both complex and expensive. 

Clayton, RN. and Mayeda, T.K. 1963 The use ofbromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochimica et CosmochimicaActa 27 43-52. 

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