Process for treating a fibrous material suspension using combination of low-intensity and high-intensity flotation

A process for removing interfering materials from an aqueous fibrous material suspension comprising:

• subjecting the aqueous fibrous material suspension to at least two flotation processes;
• performing one of the at least two flotation processes under a low-intensity gravitational field effect as a low-intensity flotation process in a gravitational field;
• performing another of the at least two flotation processes under a high-intensity gravitational field effect as a high-intensity flotation process;
• and
• processing the material to remove fibers,
• wherein the processing is a mechanical process occurring between the at least two flotation processes.

A process for removing fibers from a material in an aqueous fibrous material suspension comprising:

• subjecting the aqueous fibrous material suspension to at least two flotation processes;
• performing one of the at least two flotation processes under a low-intensity gravitational field effect as a low-intensity flotation process;
• performing another of the at least two flotation processes under a high-intensity gravitational field effect as a high-intensity flotation process in a gravitational field;
• producing the gravitational field by centrifugal force, wherein the centrifugal force is at least a two-fold increase in the gravitational field;
• and
• processing the material to remove fibers, wherein the processing is a mechanical process occurring between the at least two flotation processes.