# US 5,707,529 A · Method for controlling scale in an aqueous system using a synergistic combination > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,529 A - Document ID: US5707529A - Status: Granted - Kind: A - Application number: 08/718,840 - Filed: 1996-09-24 - Granted: 1998-01-13 - Earliest claimed: 1996-09-24 - Assignees: Calgon Corporation - Inventors: Jasbir S. Gill; Jennifer R. Parsons - Web page: https://patentgrep.com/patent/US5707529A ## CPC - C02F 5/14: containing phosphorus - C23F 11/10: using organic inhibitors - C23F 14/02: by chemical means - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) - C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25 ## Abstract A method for inhibiting the formation, deposition and adherence of scale forming salts including calcium carbonate and calcium phosphate in an aqueous system having a pH of at least 8.5 and a calcite saturation level of at least 100 times the solubility limit of calcium as calcite, including adding to the aqueous system a synergistic effective amount of a combination comprising (A) a polyether polyamino methylene phosphonate, (B) a terpolymer comprising the monomers of acrylic acid, sulfophenoxymethallyl ether and maleic acid, (C) a hydroxyphosphonoacetic acid, and (D) a phosphonocarboxylic acid copolymer. ## Claims ### Claim 1 A method of inhibiting the formation, deposition and adherence of scale forming salts, including calcium carbonate and calcium phosphate in an aqueous system having a pH of at least 8.5 and a calcite saturation level of at least 100 times the solubility limit of calcium as calcite, comprising adding to said aqueous system an effective synergistic amount of a combination of (A) an amount to establish a concentration of at least about 1.0 mg/L, of a polyether polyamino methylene phosphonate of the formula: ##STR11## where n is an integer or fractional integer which is, or on average is, from about 2 to about 12, inclusive; M is hydrogen or an alkali metal; and each R may be the same or different and is independently selected from hydrogen and methyl; (B) an amount sufficient to establish a concentration of at least about 2.0 mg/L of a terpolymer comprising the monomers of acrylic acid, sulfophenoxymethallyl ether and maleic acid, wherein said terpolymer has a weight average molecular weight in the range from about 4,000 to 10,000; (C) an amount sufficient to establish a concentration of at least about 0.20 mg/L of a hydroxyphosphonoacetic acid; and (D) an amount sufficient to establish a concentration of at least about 0.75 mg/L of a phosphonocarboxylic acid copolymer comprising the monomers of acrylic acid, (1-hydroxy-1-methylethyl) phosphinic acid monosodium salt and 2-acrylamido 2 methyl propane sulfonic acid, to inhibit calcium carbonate and calcium phosphate scale formation. ### Claim 2 (depends on 1) The method of claim 1 including wherein for said (A) polyether polyamino methylene phosphonate, M is hydrogen, each R is methyl, and n is from about 2 to 4. ### Claim 3 (depends on 2) The method of claim 2 including wherein n is about 2.6. ### Claim 4 (depends on 1) The method of claim 1 including wherein said aqueous system is a cycled up cooling tower. ### Claim 5 (depends on 1) The method of claim 1 including wherein said (B) terpolymer is about 84 weight average molecular weight percent acrylic acid, about 8 weight average molecular weight percent sulfophenoxymethallyl ether, and about 8 weight average molecular weight percent maleic acid. ### Claim 6 (depends on 1) The method of claim 1 including wherein the weight ratio of (A):(B):(C):(D) ranges from about 4:8:1:3 to about 5:10:1:4. ### Claim 7 (depends on 1) The method of claim 1 including adding said synergistic combination comprising said (A), (B), (C) and (D) to said aqueous system wherein said (A) polyether polyamino methylene phosphonate is present in a concentration of at least about 6.0 mg/L, said (B) terpolymer is present in a concentration of at least about 6.0 mg/L, said (C) hydroxyphosphonoacetic acid is present in a concentration of at least about 1.0 mg/L, and said (D) phosphonocarboxylic acid copolymer is present in a concentration of at least about 3.75 mg/L wherein said aqueous system has a calcite saturation level of at least 150 times the solubility limit of calcium as calcite. ### Claim 8 (depends on 1) The method of claim 1 including further adding a stabilizer to said aqueous system for preventing decomposition of said (A) polyether polyamino methylene phosphonate. ### Claim 9 (depends on 8) The method of claim 8 including wherein said stabilizer is monoethanolamine. ### Claim 10 (depends on 1) The method of claim 1 including further adding at least one corrosion inhibitor. ### Claim 11 (depends on 10) The method of claim 10 including wherein said corrosion inhibitor is a copper corrosion inhibitor. ### Claim 12 (depends on 11) The method of claim 11 including wherein said copper corrosion inhibitor is tolyltriazole. ### Claim 13 (depends on 10) The method of claim 10 including wherein said corrosion inhibitor is a steel corrosion inhibitor. ### Claim 14 (depends on 8) The method of claim 8 including further adding at least one corrosion inhibitor. ### Claim 15 (depends on 1) The method of claim 1 including wherein for said polyether polyamino methylene phosphonate, M is hydrogen, each R is methyl, and n is about 2.6, and further including adding a stabilizer to said aqueous system, and adding a corrosion inhibitor to said aqueous system. ### Claim 16 (depends on 15) The method of claim 15 including wherein said stabilizer is monoethanolamine. ### Claim 17 (depends on 16) The method of claim 16 including wherein said corrosion inhibitor is a copper corrosion inhibitor. ### Claim 18 (depends on 16) The method of claim 16 including wherein said copper corrosion inhibitor is tolyltriazole.