Degradation-resistant scale inhibitors

A method of reducing aluminosilicate containing scale in a Bayer process, comprising:

• identifying a Bayer process equipment surface that is subject to scale formation during the Bayer process;
• contacting the identified Bayer process equipment surface with an amount of a scale inhibiting composition effective to form a treated surface that is more resistant to scale formation upon subsequent contact with a Bayer process stream than an otherwise comparable untreated surface;
• and
• contacting the treated surface with the Bayer process stream;
• wherein the scale inhibiting composition comprises a liquor comprising an aqueous solution of one or more water-soluble salts having at least about 0.004% by weight of total dissolved salts and a silicon-containing compound,
• wherein the silicon-containing compound is resistant to degradation in alumina recovery process streams at process temperatures from about 100° C. to about 265° C.,
• wherein the silicon-containing compound is a reaction product of at least a polyamine, a first nitrogen-reactive compound and a second nitrogen-reactive compound,
• wherein:
• the first nitrogen-reactive compound comprises a —Si(OR1b)3 group and a nitrogen-reactive group, where R1b is H, optionally substituted C1-C20 alkyl, optionally substituted C6-C12 aryl, optionally substituted C7-C20 aralkyl, optionally substituted C2-C20 alkenyl, Group I metal ion, Group II metal ion, or NR2b4, each R2b being independently selected from H, optionally substituted C1-C20 alkyl, optionally substituted C6-C12 aryl, optionally substituted C7-C20 aralkyl, or optionally substituted C2-C20 alkenyl;
• the second nitrogen-reactive compound comprises a nitrogen-reactive group and does not contain a —Si(OR1b)3 group, and
• wherein the silicon-containing compound is free of β-hydroxy ether groups.