Abstract: A self-cleaning over door latching mechanism is provided with a locking arrangement responsive to the oven cavity temperature, which includes a locking pin moved by a snap action bimetal member mounted in thermal communication with an oven cavity wall. The bimetal member moves the locking pin to a locking position when the temperature sensed by the bimetal rises above the locking temperature. In its locked position the locking pin prevents the opening of the latch until the temperature in the oven cavity falls below the locking temperature. In its locked position the locking pin also actuates a lock switch electrically connected in parallel with a thermal limit switch. The thermal limit switch provides over temperature protection for the cavity when operating in the normal cooking modes. When actuated, the lock switch shunts the limit switch thereby enabling the temperature in the cavity to rise to the self-clean range.

Abstract: Method for the recovery of high purity Cr.sub.2 O.sub.3 from a Na.sub.2 CrO.sub.4 or Na.sub.2 Cr.sub.2 O.sub.7 solution by producing (NH.sub.4).sub.2 CrO.sub.4 by solvent extraction, evaporating the aqueous (NH.sub.4).sub.2 CrO.sub.4 and igniting the resulting solids to provide high purity Cr.sub.2 O.sub.3.

Abstract: Method for the recovery of chrome hydrate or high purity Cr.sub.2 O.sub.3 from chromium ores by roasting the ore with Na.sub.2 CO.sub.3 and CaO, water leaching the roasted mass, precipitating aluminum impurities from the leach liquor as Al(OH).sub.3 and contacting the leach liquor with sulfur and NaOH in order to reduce the chromium values in the leach liquor from valence 6 to 3 to provide a chrome hydrate precipitate. The chrome hydrate precipitate is acid repulped to provide a chrome hydrate from which sodium impurities have been removed. The chrome hydrate is dried and the resulting solids are calcined to provide a high purity Cr.sub.2 O.sub.3.