Iron continued solutions

Four precipitated iron-based catalysts were used. The first catalyst consisted of only iron. The other catalysts contained either added potassium, added silicon or both. The catalysts were designated in terms of the atomic ratios as lOOFe, 100Fe/3.6Si, 100Fe/0.71K and 100Fe/3.6Si/0.71K. The catalysts were prepared by continuous precipitation from iron (111) nitrate and concentrated ammonium hydroxide. For silica-containing catalysts, a colloidal suspension of tetraethyl ortho silicate was mixed with the iron nitrate solution prior to precipitation. Potassium was added to the catalysts in the form of potassium tertiary butoxide during the loading of the FTS reactor. 

The Ni, Co, Zn, Cu, Mn levels increased during each leach experiment. The Fe levels in solution peak and stay high for most of the first series of four experiments with variable acid addition. For the second series of four higher temperature experiments (with oxygen sparging) there was a marked decrease in the iron in solution with time due to oxidation and precipitation as hydronium jarosite. The jarosite precipitation is a favourable reaction as the acid released upon Fe precipitation continues to leach Ni and other metals. The nickel extraction rose with increased temperature of leaching. 

Add the chilled iron(ll) solution to the reaction mixture once its temperature has reached -10°C (care ).° Stir for 5 min at -10°C and then continue stirring at room temperature until two layers are formed. 

LO-CATII Process. In 1990, ARl introduced the AQUA-CAT process to remove H2S from waste water. In this process the chelated iron chelate solution was continuously added to the waste water feed and discarded with the treated water. As the iron chelate solution was lost, the economics of the process hinged on whether or not the concentration of chelated iron could be held at substoichiometric levels. It was found that the process was still effective when the concentration of chelated iron was well below a 2 I ferric ion to H2S stoichiometric ratio. This ratio was the minimum level that the LO-CAT process historically had tried to maintain. 

In a 500 ml. bolt-head flask, provided with a mechanical stirrer, place 70 ml. of oleum (20 per cent. SO3) and heat it in an oil bath to 70°. By means of a separatory funnel, supported so that the stem is just above the surface of the acid, introduce 41 g. (34 ml.) of nitrobenzene slowly and at such a rate that the temperature of the well-stirred mixture does not rise above 100-105°. When all the nitrobenzene has been introduced, continue the heating at 110-115° for 30 minutes. Remove a test portion and add it to the excess of water. If the odour of nitrobenzene is still apparent, add a further 10 ml. of fuming sulphuric acid, and heat at 110-115° for 15 minutes the reaction mixture should then be free from nitrobenzene. Allow the mixture to cool and pour it with good mechanical stirring on to 200 g. of finely-crushed ice contained in a beaker. AU the nitrobenzenesulphonic acid passes into solution if a little sulphone is present, remove this by filtration. Stir the solution mechanically and add 70 g. of sodium chloride in small portions the sodium salt of m-nitro-benzenesulphonic acid separates as a pasty mass. Continue the stirring for about 30 minutes, allow to stand overnight, filter and press the cake well. The latter will retain sufficient acid to render unnecessary the addition of acid in the subsequent reduction with iron. Spread upon filter paper to dry partially. 

Analytical Procedures. Standard methods for analysis of food-grade adipic acid are described ia the Food Chemicals Codex (see Refs, ia Table 8). Classical methods are used for assay (titration), trace metals (As, heavy metals as Pb), and total ash. Water is determined by Kad-Fisher titration of a methanol solution of the acid. Determination of color ia methanol solution (APHA, Hazen equivalent, max. 10), as well as iron and other metals, are also described elsewhere (175). Other analyses frequendy are required for resia-grade acid. For example, hydrolyzable nitrogen (NH, amides, nitriles, etc) is determined by distillation of ammonia from an alkaline solution. Reducible nitrogen (nitrates and nitroorganics) may then be determined by adding DeVarda s alloy and continuing the distillation. Hydrocarbon oil contaminants may be determined by ir analysis of halocarbon extracts of alkaline solutions of the acid. 

Tungsten with the addition of as much as 5% thoria is used for thermionic emission cathode wires and as filaments for vibration-resistant incandescent lamps. Tungsten—rhenium alloys are employed as heating elements and thermocouples. Tantalum and niobium form continuous soHd solutions with tungsten. Iron and nickel are used as ahoy agents for specialized appHcations. 

The tertiary metal phosphates are of the general formula MPO where M is B, Al, Ga, Fe, Mn, etc. The metal—oxygen bonds of these materials have considerable covalent character. The anhydrous salts are continuous three-dimensional networks analogous to the various polymorphic forms of siHca. Of limited commercial interest are the alurninum, boron, and iron phosphates. Boron phosphate [13308-51 -5] BPO, is produced by heating the reaction product of boric acid and phosphoric acid or by a dding H BO to H PO at room temperature, foUowed by crystallization from a solution containing >48% P205- Boron phosphate has limited use as a catalyst support, in ceramics, and in refractories. 

Other reactions taking place throughout the hardening period are substitution and addition reactions (29). Ferrite and sulfoferrite analogues of calcium monosulfoaluminate and ettringite form soHd solutions in which iron oxide substitutes continuously for the alumina. Reactions with the calcium sihcate hydrate result in the formation of additional substituted C—S—H gel at the expense of the crystalline aluminate, sulfate, and ferrite hydrate phases. 

The difference in stability between FeO and NiO is not as large as that between iron and copper oxides, and so the preferential oxidation of iron is not so marked in pentlandite. Furthermore, the nickel and iron monoxides form a continuous series of solid solutions, and so a small amount of nickel is always removed into die oxide phase (Table 9.2). 

The iron, now in a reduced ferrous form, is not consumed instead, it is continuously regenerated by bubbling air through the solution. The sulfur precipitates out of the solution and is removed from the reactor with a portion of the reagent. The sulfur slurry is pumped to a melter requiring a small amount of heat and then to a sulfur separator where the reagent in the vapor phase is recovered, condensed, and recycled back to the reactor. 

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. 

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