Abstract: Fire-retardant sheet element can be composed of several fire protection glass plates (2, 3). Lateral edges (9, 10) of adjacent glass plates (2, 3) therein abut one another. Into the interspace (26) between lateral edges (9, 10) a sealing configuration (7) is installed. This comprises an addition element (22) and elastic sealing elements (23, 24). The glass plates (2, 3) comprise several glass panes (16) and interspaced fire protection layers (18). These fire protection layers (18) do not extend up to the edges (9, 10) and are sealed in the regions of the lateral edges with a barrier material (20). No additional frame elements for covering the interspace (26) and for sealing are necessary.

Abstract: Glass plates are thermally or chemically tempered to increase flexural bending strength. The tempered plates are subsequently subjected to a heat treatment in order to lower the possibility of spontaneous breakage of the glass plates. According to the method according to the invention the glass plates are tempered at least twice and again heat-treated. At least the second heat treatment takes place at higher temperatures than were used previously. The treated glass plates have increased flexural bending strength and reduced tendency to spontaneous breakage.

Abstract: The heat protection element comprises carrier elements, for example in the form of glass plates. In an interspace between, in each instance, two glass plates a protection layer comprising a cured polysilicate which is formed of alkali silicate and at least one curing agent is disposed. In the polysilicate, a molar ratio of silicon dioxide to alkali metal oxide is set to be greater than 4:1. The starting composition for the polysilicate is a free-flowable composition having a water content of up to 60 percent and capable of being introduced into the interspace between two carrier elements. After curing the composition, the high water content is retained and the polysilicate has nevertheless good inherent strength and adhesion on the carrier elements.

Abstract: A process is disclosed for the regeneration of pickling solutions which contain ZrF.sub.4 by addition of a Na compound in which a charge of the pickling solution to be regenerated is analyzed and heated. The amount of Na required for the regeneration is determined in each case and is admixed with intense stirring. Then the mixture is cooled, the precipitated NaZrF compounds are separated and a regenerated pickling solution is recovered.

Abstract: In a process of recovering oil from oil-containing minerals on a traveling grate, hot gases are passed through the bed in a retorting zone, oil is separated from the retort gases in a separating stage, solid carbon in the retorted bed is burnt in a succeeding combustion zone by means of oxygen-containing gases passed through, gases from which the oil has been removed in the separating zone are passed through the bed in a succeeding cooling zone and the heated gases are recycled to the retorting zone.

Abstract: Oil-containing materials and part of the hot burnt material which is available after the combustion of solid carbon are charged into a retorting shaft reactor and the oil-containing mineral in the mixture is heated to the retorting temperature.

Abstract: A process is disclosed for cleaning waste gases generated in an at least partially covered movable grate-type sintering line, said sintering line comprising an ignition zone, a sintering zone and a burning zone, wherein waste gases generated in the burning zone are returned to the sintering zone, passed through the sinter charge and at least those waste gases emerging from the last third of the sintering zone are scrubbed after passage through the charge.