Patent ID: 6881298

Claim:
A process for loading calcium carbonate into fibers contained in a pulp suspension, the process comprising the steps of: providing a pulp suspension comprised of fibers; providing a calcium-rich medium, said calcium-rich medium being comprised of at least one of calcium oxide and calcium hydroxide; adding controlled amounts of said calcium-rich medium to said pulp suspension and thereby forming a controllably variable calcium-treated pulp suspension; providing a plurality of reactors, each reactor being fluidly coupled to a source of a carbon-dioxide medium, said carbon-dioxide medium being one of pure carbon dioxide and a medium containing carbon dioxide; charging said calcium-treated pulp suspension and said carbon-dioxide medium into a first reactor to promote a chemical reaction to form calcium carbonate and thereby load said fibers with said calcium carbonate; controlling the chemical reaction in the first reactor by selectively adding the carbon dioxide medium in at least one location of upstream, of the first reactor, into the first reactor and downstream of the first reactor, and selectively controlling temperatures of the pulp suspension and the carbon-dioxide medium in at least one location of upstream of the first reactor, in the first reactor and downstream of the first reactor; charging a second reactor with said carbon-dioxide medium and at least one of said calcium-treated pulp suspension and fibers loaded with calcium carbonate from said first reactor; and controlling a chemical reaction in the second reactor to form calcium carbonate with different types of crystals from said calcium carbonate formed in said first reactor, and thereby loading said fibers in said second reactor with said different types of calcium carbonate crystals, including selectively adding the carbon dioxide medium in at least one location of upstream of the second reactor, into the second reactor, and downstream of the second reactor, and selectively controlling temperatures of the pulp suspension and the carbon-dioxide medium in at least one location of upstream of the second reactor, in the second reactor and downstream of the second reactor.