Abstract: This invention relates to a process of producing magnesia from magnesium-containing carbonate ores, which comprises leaching with sulfuric acid, subsequently neutralizing the solution with magnesia, separating the undissolved impurities, crystallizing magnesium sulfate under pressure and above 150.degree. C so the crystals have from 1.5 to 4 moles of water per magnesium sulfate molecule and thermally decomposing the latter to form magnesia and SO.sub.2, recovering sulfuric acid from the sulfur dioxide produced in the decomposing steps and recycling the sulfuric acid to the leaching stage.

Abstract: Thermal decomposition of aluminum chloride hydrate in a fluidized bed reactor in which the concentration of solids diminishes from the bottom upwards, the improvement wherein most of the hydrogen chloride is removed from the hydrate by direct heat and the largely decomposed aluminum chloride is fed into a calcining reactor and from the calcining reactor to a residence time reactor fluidized at low gas velocity, recycling solids from the residence reactor to the calcining reactor in an amount to adjust the suspension density and feeding the remainder to a cooler after sufficient time in the residence reactor.

Abstract: Process for the thermal decomposition of aluminum chloride hexahydrate into anhydrous Al.sub.2 O.sub.3, comprising predrying and then decomposition in a fluidization reactor, the said fluidization being ensured by recycled gaseous HCl, and finally heating at the temperature necessary to obtain the desired crystallization state, namely anhydrous Al.sub.2 O.sub.3, the said pre-drying being carried out by the gases coming from this final heating.

Abstract: Endothermic processes are carried out in a fluidized-bed reactor which is connected to a holding reactor, solids being recirculated between the two reactors. The primary fluidized-bed reactor uses a fast-fluidized bed system in which the solids concentration decreases continuously from the bottom to the top of the reactor. After the necessary residence time in the holding reactor, solids are discharged. Solids are entrained with the gas stream from the primary reactor and are separated therefrom to be delivered to the holding reactor. The reaction is controlled by regulating the rate of recirculation of solids from the holding reactor to the fast fluidized bed reactor.

Abstract: A method of reducing a pulverized material containing iron oxides mixed with carbonaceous material wherein: (a) a circulating fluidized bed is maintained in a vertically elongated reaction zone by supplying it with suitable quantities of pulverized material containing iron oxides, pulverized solid carbonaceous material and optionally liquid carbonaceous material, and gas containing molecular oxygen and that gas and solid material leaving the reaction zone are separated, the solid material being returned to the reaction zone; (b) the pulverized material containing iron oxides, the carbonaceous material and the gas containing molecular oxygen are supplied to an intermediate section of the reaction zone; (c) the flow of carbonaceous material fed to the bed is controlled so that there is always sufficient coke in the bed to prevent interference of the fluidization caused by sticking or agglomeration; (d) gas and solid material leaving the reaction zone are extracted from the upper part of the reaction zone, the s

Abstract: Hydrogen fluoride is removed from gases by introducing the gases into a fluidized-bed reactor to form a gas-solid suspension, entraining a major part of the solids in an upward direction separating the solids entrained by the gases without prior removal of the solids from the gas-solid suspension, by means of an electrostatic precipitator.

Abstract: Gases having a high SO.sub.2 content are catalytically reacted in a contacting zone having a plurality of series-connected contacting trays. A partial stream of partly reacted gases from the contacting zone containing SO.sub.3 is admixed with the SO.sub.2 containing gas before entering the first contacting tray. The gases are subjected to interstage cooling between contacting trays. At least a portion of the partly reacted gases is passed through an absorber prior to mixing with the feed stock gas having a high SO.sub.2 content. The rate at which SO.sub.3 is absorbed is increased in dependence on the loss of catalyst activity in the contacting zones such that the conversion of SO.sub.2 to SO.sub.3 in the contacting trays remains approximately constant.

Abstract: A process for removing sulfur trioxide from gases wherein the sulfur trioxide-containing gas is treated with sulfuric acid in a Venturi absorber, the sulfur-trioxide laden sulfuric acid is passed in indirect heat exchange with a cooling fluid within the widening outlet of the absorber and the sulfur trioxide-laden sulfuric acid is separated from the gas phase.