Process for producing aqueous polyacrylamide solutions

A process for producing an aqueous polyacrylamide solution comprising polymerizing an aqueous solution comprising at least acrylamide thereby obtaining an aqueous polyacrylamide gel and dissolving said aqueous polyacrylamide gel in water, characterized in that the process comprises at least the following steps:

• [0] hydrolyzing acrylonitrile in water in the presence of a biocatalyst capable of converting acrylonitrile to acrylamide, thereby obtaining an aqueous acrylamide solution at a location A,
• [1] preparing an aqueous monomer solution comprising at least water and 15% to 24.9% by weight—relating to the total of all components of the aqueous monomer solution—of water-soluble, monoethylenically unsaturated monomers at a location A, wherein said aqueous solution comprises at least the aqueous acrylamide solution prepared in course of step [0],
• [2] inerting and radically polymerizing the aqueous monomer solution prepared in step [1] in the presence of suitable initiators for radical polymerization under adiabatic conditions at a location A, wherein
• the polymerization is performed in a transportable polymerization unit having a volume of 5 m3 to 40 m3,
• the aqueous monomer solution has a temperature T1 from −5° C. to +5° C. before the onset of polymerization, and
• the temperature of the polymerization mixture raises in course of polymerization—due to the polymerization heat generated—to a temperature T2 from 50° C. to 70° C.,
• thereby obtaining an aqueous polyacrylamide gel having a temperature T2 which is held in the transportable polymerization unit,
• [3] transporting the transportable polymerization unit filled with the aqueous polyacrylamide gel from location A to a different location B,
• [4] removing the aqueous polyacrylamide gel from the transportable polymerization unit at the location B, and
• [5] comminuting and dissolving the aqueous polyacrylamide gel in an aqueous liquid at the location B, thereby obtaining an aqueous polyacrylamide solution.

A process for producing an aqueous polyacrylamide gel comprising polymerizing an aqueous solution comprising at least acrylamide, characterized in that the process comprises at least the following steps:

• [1] preparing an aqueous monomer solution comprising at least water and 5% to 45% by weight—relating to the total of all components of the aqueous monomer solution—of water-soluble, monoethylenically unsaturated monomers at a location A, wherein said water-soluble, monoethylenically unsaturated monomers comprise at least acrylamide,
• [2] inerting and radically polymerizing the aqueous monomer solution prepared in step [1] in the presence of suitable initiators for radical polymerization under adiabatic conditions at a location A, wherein
• the polymerization is performed in a transportable polymerization unit having a volume of 1 m3 to 40 m3,
• the aqueous monomer solution has a temperature T1 not exceeding 30° C. before the onset of polymerization, and
• the temperature of the polymerization mixture raises in course of polymerization—due to the polymerization heat generated—to a temperature T2 of at least 45° C.,
• thereby obtaining an aqueous polyacrylamide gel which is held in the transportable polymerization unit.