Iron sulphate, calcined

The catalyst. The catalyst was prepared by coprecipitation of iron(III)hydroxide and zinc(II)hydroxide from a nitrate solution with ammonia. After the precipitate was dried and calcined, about 0.006 weight percent of iron sulphate was impregnated on the material. In earlier studies this impregnation proved to stabilize the catalyst. The catalyst was in situ reduced in pure hydrogen at 625 K and 100 kPa. Prior to the experiments, the reduced catalyst was activated in a continuous stream of synthesis gas (20% CO 20% H2 60% He) at 550 K. 

Isobutyl vinyl ether has recently been polymerised by iron sulphate following the calcination of the initiator at 700°C. The same treatment at 750°C gives an inactive salt. Obviously, the key point about the activity of this compound has to do with some particular crystalline structure which is modified between these two temperatures. 

There are now two processes in widespread use for making titanium dioxide pigments. In the sulphate process, finely ground ilmenite is digested in sulphuric acid and the iron is reduced and separated as iron(II) sulphate. The titanium(IV) sulphate is hydrolysed by steam to a hydrous oxide, which is thoroughly washed to remove soluble impurities and finally calcined at a temperature of about 1000 °C to give the anatase form of titanium dioxide. 

The starting material for making these pigments is cadmium sulphate, which must be free from iron, nickel and copper impurities. Cadmium sulphide is precipitated from the sulphate solution by adding an alkaline solution of pure sodium sulphide under controlled conditions of pH, temperature and addition rate. The yellow product is in the cubic crystal form, which is converted into the required hexagonal form by calcination at 500-600 °C in the absence of air. 

Red, brown and black iron oxides are prepared by first heating green iron(II) sulphate crystals to remove six of the molecules of water of crystallisation (leaving FeS04.H20) and then calcining the product to the desired form of iron(III) oxide with the evolution of sulphur oxides. 

The ash is mixed with 5 to 10 per cent, of slaked lime and placed in wooden barrels with false bottoms. Hot water is poured over the mixture, and, after standing for some time, the liquid is drawn off from time to time by removing a plug near the bottom of the cask. The liquid with a sp. gr. over 1 -15 is evaporated the low sp. gr. liquor may be used for lixiviating more ash and the residue in the barrels may be used as manure. The evaporation of the densest liquor to dryness is conducted in cast-iron pots, and the residue is afterwards calcined in a reverberatory furnace to burn away the organic matter—at the same time sulphates may be converted into sulphides. The product is crude potash. The crude potash may be mixed with sawdust and re-calcined. It is then digested with twice its weight of hot water, filtered, and cooled. The less soluble impurities—mainly potassium sulphate—crystallize out, and finally the mother liquid is evaporated to dryness and calcined as before, - or the solu. may be evaporated until crystals of potassium carbonate are deposited. 

The sodium chloride and sulphate regularly found in Leblanc soda ash are not usually injurious the insoluble matter should not exceed 1 to 1J per cent. It consists principally of calcium carbonate, alumina, silica, and ferric oxide. The sulphides should not be detectable by lead paper thiosulphates are destroyed in calcining the ash sulphites are usually present and can be detected by iodine soln. and sodium hydroxide, except in the so-called caustic ash, does not usually exceed 1 per cent. The moisture in fresh ash ranges below one per cent. Owing to the mode of preparation, ash by Solvay s process is more pure than that prepared by Leblanc s process. It does not contain sodium hydroxide, sulphides, sulphites, or thiosulphates it may contain a slight excess of carbon dioxide a little sodium sulphate is always present iron, alumina, and silica are present in minute traces sodium chloride is perhaps the only... 

J. T. Way, and T. Twynam heated Thomas slag with soda, and extracted the alkali phosphate with M ater. N. A, Helouis and M. Rychonnet, L. Imperatori, and F. Jean calcined a mixture of the phosphate with sodium sulphate and carbon C. Schwarz, and M. Boblique heated the mineral with iron so as to make ferric phosphate, which was then heated with sodium sulphate and carbon. In each of these cases the alkali phosphate was leached from the mass. M. Drevermann treated the iron phosphate with sodium sulphide, C. Clemm with potassium sulphide. 

Aluminium fluoride (anhydrous) [7784-18-4] M 84.0, m 250". Technical material may contain up to 15% alumina, with minor impurities such as aluminium sulphate, cryolite, silica and iron oxide. Reagent grade AIF3 (hydrated) contains only traces of impurities but its water content is very variable (may be up to 40%). It can be dried by calcining at 600-800° in a stream of dry air (some hydrolysis occurs), followed by vacuum distn at low pressure in a graphite system, heated to approximately 925° (condenser at 900") [Henry and Dreisbach JACS 81 5274 7959]. 

The other process for the conversion of cliloride of sodium into sulphate of soda, by means of sulphate of iron, consists in the calcination at a red heat, in a reverberatory furnace, of an. intimate mixture of the... 

Fixed Residue.—2 grams of the substance are calcined in a porcelain crucible, which is heated at first gently and afterwards gradually more and more intensely to bright redness, the residue being weighed. If this is in appreciable quantity, it is analysed qualitatively, especially for lead, iron, chromium, silicates and barium and calcium sulphates. 

The residue of the calcination is treated with hydrochloric acid, the solution and any insoluble residue remaining being then analysed by the ordinary methods. Tests are made especially for alumina, zinc oxide, tin oxide, lead oxide, barium sulphate and calcium carbonate, and also for oxides of chromium, iron, copper and antimony, silicates and gypsum. 

The crude oxide is dissolved in hydrochloric add. To the warm liquor finely divided calcium carbonate is added gradually, with stirring, until no further predpitate is obtained. The precipitate being removed by filtration, the solution is free from iron, arsenic, and silica. The solution is then precipitated with a solution of bleaching powder,2 added slowly with constant stirring until almost the whole of the cobalt is precipitated as black hydrated oxide. By this means practically none of the nickel is thrown down. The precipitate is washed, dried, and calcined to oxide. It is then boiled with sodium carbonate solution to convert any calcium sulphate into carbonate, and after thorough washing, is treated with very dilute hydrochloric acid to remove the calcium carbonate. Finally the oxide is washed, dried, and calcined. 

Metallic iridium is thus obtained together with oxide of iron. The whole is heated to redness with potassium hydrogen sulphate, which removes the iron and any remaining traces of rhodium. The residue is well washed with water, then with chlorine water to remove any traces of gold, and finally with hydrochloric acid to take out any silica which may have accidentally been introduced with the alkalies or have come from the vessels employed. The resulting iridium is calcined with charcoal and melted into an ingot. 

Conversion into the sulphate is effected by weathering, a slow and expensive process by calcination, for ores containing a high percentage of iron pyrites by calcination with ferrous or aluminium sulphate or by calcination with ferric sulphate as an adjunct to the weathering process. 

The formation of the chlorides is effected in the dry way by calcination with sodium chloride or in the wet way by interaction with ferrous chloride and hydrochloric acid or with ferric chloride. The wet way is only adopted if fuel is scarce, or the escape of noxious vapours into the atmosphere is not permissible. In the dry method the ore is oxidized by a preliminary roasting, and then chloridized by calcination with sodium chloride or Abraum salts in a furnace of the reverberatory or muffle type, the principal product being cupric chloride. The Dotsch modification of the wet process, worked at Rio Tinto, depends on the action of ferric-chloride solution on a mixture of the ore with sodium sulphate and ferric chloride. The liquid drawn off from the bottom of the heaps of ore contains cuprous chloride in solution as a complex salt. The copper is liberated by the action of iron, the ferrous chloride simultaneously formed being chlorinated in towers to ferric chloride, and the product employed for moistening the heaps of ore. 

Crystals of magnetic oxide have been obtained in a variety of ways, such as by calcination of sodium carbonate and ferrous chloride 1 by fusion of potassium sulphate and iron phosphate 2 by the action of hydrogen chloride upon heated ferrous oxide 3 and by ignition of ferrous fluoride with boric anhydride.4... 

Potassium Dichromate, KjCcjO, may be prepared from the sodium salt and potassium chloride, or by a direct method. In the latter ease, chrome iron ore (p. 7) is calcined in the air with calcium carbonate, and the mass extracted with water containing a little sulphuric acid. Potassium carbonate is then added, and, after filtration and addition of sulphuric acid, the potassium dichromate is separated by fractional crystallisation. An alternative method consists in heating chromite with calcium carbonate and potassium sulphate, and lixiviating the mass with water. Oxidation of chromite by means of fused potassium nitrate is sometimes convenient, especially upon a small scale. Potassium dichromate is formed by the addition of any acid to a solution of potassium chromate (see p. 4.4 ). ... 

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