Calcium oxide, alkalizer

The presence of transition metal compounds as oxidation catalysts can cause rapid degradation of calcium carbonate-alkalized papers under humid conditions. Magnesium carbonate offers better protection than calcium carbonate. 

This test may not be carried out on paper because the slight excess of alkali cannot be added conveniently, and a deep red may be formed even in the absence of ammonium salts. However, the test can be carried out on a spot plate if calcium oxide is used as alkalizer. 

The proposed method to process these wastes [11, 13], shown schematically in Fig. 1, consists of leaching them with hot water (1), filtrating (2), treating with mineral acid to pH 3-5 (released nitrous oxides are fixed in the absorption tower), alkalization with ammonia water to pH 7-8 (4), precipitation with the soluble calcium salt to calcium molybdate (5) filtration and washing (6) of the precipitate (7) which can be processed (8) to other molybdenum compounds (9). 

Aluminum and ferrosilicon anodes are suitable for the protection of hot water tanks. The use of aluminum anodes in a hot water apparatus has additional effects, an indirect protective action on subsequent piping, since a protective film (1-1.5 mm thick) is built up by anode-formed aluminum oxide hydrates. In addition to alkalization at the cathode, a shift in the calcium carbonate (CaCOj)-CO2 equilibrium leads to partial softening of water, with CaC03 being deposited at the cathode. 

---