Abstract: Method for amperiometrically measuring the bacterial content of liquids in a bioelectrochemical cell wherein the mediator is initially oxidized in the cell, then brought into contact with a capturing system containing the bacteria of the sample, resulting in a first response at the electrodes, and finally brought into contact again with the capturing system after the bacteria present have been killed, producing a second response due to the interfering substances, which is subtracted from the first response. An apparatus is also provided for implementing this method.

Abstract: In the direct reduction of iron ore in a series of fluidized beds, for the production of carburized iron sponge briquettes for use in electric furnaces, carburization is carried out after the last fluidized bed, at a temperature of 600.degree. to 700.degree. C., by batching the reduced iron powder with a solid finely divided carbonaceous material and then briquetting the mixture, in an inert atmosphere.

Abstract: Iron ore is introduced in a series of fluidized bed reactors, with a reducing gas that is heated before each bed and cooled after each bed and thereafter washed with water so as to remove from the gas the very fine powder of solids which otherwise would build up in the reactors. The reducing gas can be divided and fed to the reactors in parallel, the gas from all the reactors being recombined and subjected to washing, addition of make-up gas, and recompression, prior to recycling in a plurality of parallel streams. Alternatively, the reducing gas can proceed from the final reactor in reverse order to the passage of iron ore through the reactors, with heating of the gas before each reactor and cooling and washing of the gas after each reactor, followed by addition of make-up and recompression prior to recycling.

Abstract: Iron ore is reduced in a multiple fluid bed reactor, the beds being vertically superposed in a tower and the ore passing by gravity downwardly from bed to bed. The lowermost and all superposed beds are fluidized by off gases from which carbon dioxide and water have been stripped; while a further portion of the fluidizing and reducing gas is provided by combusting methane with a substoichiometric quantity of oxygen and introducing the combustion products into an intermediate level of the column.

Abstract: A plate for fluid bed reactors to insure uniform distribution of the fluidizing gas, comprises a pair of spaced opposed plates having holes therethrough, the holes in one plate being staggered relative to those of the other plate. The peripheral holes are larger than the central holes. The holes in the upper plate have upper frusto-conical parts and lower cylindrical parts, while the holes in the lower plate have upper cylindrical parts and lower frusto-conical parts. The plates have central holes closed by frusto-conical plugs operable from outside the associated apparatus to discharge material from the plate.