Calcined pyrites

A particularly suitable diluent is the iron oxide residue left after digestion, but calcined pyrites can also be used. A typical digestion mixture consists of ... 

Metal sulphides. Many metals (e.g., iron, copper, lead, nickel) are found as mineral ores in sulphide form (pyrites) of which iron sulphide is most common. These are concentrated by physical and chemical means to produce an ore ready for economical extraction. Some may be subject to oxidation to generate heat, deplete oxygen, and emit toxic fumes. Calcined pyrites are used in the production of sulphuric acid and sulphur dioxide. In the presence of moisture, the calcined residue or dust can generate acids. 

Siilfuric acid from iron pyrites Paint pigments roasting of metallic oxides Refractory clays calcination of refractory clay to reduce shrinkage Foundry sand removal of carbon from used foundry sand Fullers earth calcination of fuller s-earth material... 

Several important applications of fluid beds exist outside the petroleum industry. Fluid bed roasting of pyritic ores is widely used in the metallurgical industry. Calcination of lime is a commercial process. There are also fluidization processes for various nuclear processing steps. 

SULF-X [Sulfur extraction] A regenerable flue-gas desulfurization process in which the sulfur dioxide is absorbed by aqueous sodium sulfide in a bed packed with pyrite. Ferrous sulfate is produced this is removed by centrifugation and calcined with coke and fresh pyrite. Sulfur vapor is evolved and condensed, and the residue is re-used in the scrubber. Piloted in the mid-1980s. Not to be confused with Sulfex or Sulph-X. 

Plate 19.11 Use of iron oxides as paints a) Summer house of C. F. Lnne near Upsala, Sweden, painted with hematite produced by calcination of pyrite (Courtesy Mrs. D. Schwertmann). b) House of the Lenbach Art Gallery, Munich, painted with goethite (Courtesy Dr. J. Friedel). 

The same effect is produced by magnesia whitened, arsenikon transformed, cadmia calcined, sandarach unburned, pyrites whitened, and cerussa digested with sulphur. You can soften iron by mixing with it magnesia or a small portion of sulphur, or a little magnetic stone, for the magnetic stone (lodestone) has an attraction for iron. Nature charms Nature.24... 

Figure 17. Weak acid recovery plant used by Sachtleben Chemie (based on know-how of Bayer AG) a) Heat exchanger b) Evaporator c) Injection condenser d) Stirred salt maturing vessels e) Filter press f) Bunker for pyrites g) Coal silo h) Bunker i) Mixing screw unit j) Covered store for mixed filter cake k) Calcination furnace 1) Waste-heat boiler m) Cyclone n) Electrostatic precipitator o) Stirred tank p) Storage tank q) Pump r) Cooler...

Cement, dry process Cement, wet process, 44% water Limestone calcination Dolomite calcination Alumina preparation Barium sulfide preparation Ignition of inorganic pigments Iron pyrite roasting... 

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. 

After lixiviation of the sulphate, oxide, or chlorides obtained by these methods, the copper is precipitated by the process already described. If the cement copper thus obtained contains over 55 per cent, of the metal, it is refined directly, if the percentage is lower, it is first smelted with matte or calcined copper pyrites. 

Sulfur dioxide is also produced by roasting sulfidic ores. Pyrites is, for example, converted into sulfur dioxide and iron(III) oxide (calcine) according to the following equation ... 

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