Abstract: Disclosed is a process in which a phosphate layer is formed on a metal surface in preparation for the subsequent application of a vitreous enamel coating, wherein a phosphating solution is used which contains essentially nickel and/or cobalt as a layer-forming cation in amounts of 0.5 to 3 g/l as well as5 to 20 g/l phosphate (calculated as P.sub.2 O.sub.5),0.1 to 0.5 g/l molybdate (calculated as MoO.sub.3),0.2 to 2 g/l fluoride (calculated as F),1 to 10 g/l nitrate (calculated as NO.sub.3),and optionally also 0.1 to 5 g/l urea.It is particularly desirable to use essentially zinc-free phosphating solutions at temperatures preferably of 60.degree. to 70.degree. C. for 2 to 12 minutes to form a phosphate layer having a coating weight of 1.0 to 2.0 g/m.sup.2.

Abstract: Disclosed is a process of removing zinc from a phosphating process sludge wherein the phosphating process sludge is mixed with an additive adapted to form slaglike compounds of iron, calcium and/or barium with the phosphorus component of the phosphating process sludges. The mixture is reacted at temperatures of at least 800.degree. C. under reducing conditions. A previous agglomeration, particularly pelletizing, of the mixture will be of advantage. For a formation of iron compounds it will be particularly desirable to employ reaction temperatures of at least 900.degree. C., preferably of at least 1000.degree. C. and most preferably of at least 1100.degree. C. Metallurgical dusts are particularly suitable additives. For a formation of iron compounds it will be desirable to select a Fe:P molar ratio of at least 1.0 in case of a reaction temperature of .ltoreq.950.degree. C., of at least 1.5 in case of a reaction temperature of 950.degree. to 1050.degree. C., and of at least 2.

Abstract: The activating agent which is based on titanium(IV) phosphate and intended for use in the activation of metal surfaces before a zinc phosphating treatment contains one or more copper compounds and has a Ti:Cu weight ratio of 1:100 to 60:1 and optionally contains in addition at least one of the components consisting of condensed phosphate, silicate, complexing agent, water-soluble organic polymer, thickening agent, and surfactant. It is used to prepare aqueous activating baths for activating iron, steel, galvanized steel, zinc alloy-plated steel, aluminum-plated steel and aluminum before a zinc phosphating treatment, which baths contain 0.001 to 0.060 g/l Ti, 0.020 to 1.2 g/l orthophosphate (calculated as P.sub.2 O.sub.5), and 0.001 to 0.1 g/l Cu and so much alkali that the bath has a pH value of 7 to 11, preferably of 7.5 to 10.