Method and device for loading a fibrous stock suspension

Abstract

The present invention relates to a method and a device for loading a fibrous stock suspension including a plurality of cellulose fibers with calcium carbonate. The method includes adding calcium hydroxide in liquid or dry form and / or calcium oxide into the fibrous stock suspension, adding carbon dioxide into the fibrous stock suspension, and precipitating calcium carbonate from calcium hydroxide through carbon dioxide in a pressurized vessel.

Description

BACKGROUND OF THE INVENTION [0001] This is a continuation of PCT application No. PCT / EP2005 / 008851, entitled “METHOD AND DEVICE FOR CHARGING A FIBRE MATERIAL SUSPENSION”, filed Aug. 16, 2005. [0002] 1. Field of the Invention [0003] The invention relates to a method for loading of a fibrous stock suspension with calcium carbonate. [0004] 2. Description of the Related Art [0005] Several methods for loading chemical pulp fibers with calcium carbonate are already known. A method is described in U.S. Pat. No. 6,413,365 B1 where the fibrous material is transported via a supply line together with calcium oxide and / or calcium hydroxide which are contained in said suspension. From there, the fibrous stock suspension is transported into a rotating distribution device. A reaction gas is fed in a ring shaped pattern into the fibrous stock suspension; this causes formation of calcium carbonate crystals in the fibrous suspension. The calcium carbonate crystals are distributed in the fibrous stock...

AI Technical Summary

Benefits of technology

[0010] With the method according to the current invention the currently used filler material is replaced, supplemented or activated by the filler material which is produced by the fiber loading process technology. Activation means that the already existing filler particles are superimposed by the fiber loading process or serve as a crystallization nucleus, thereby providing improved optical characteristics.

[0015] Fibrous stock produced according to the fiber loading combination process technology generally possesses a superior dewatering characteristic compared to a fibrous stock produced according to another method; the dewatering capacity is between 5 to 100 ml CSF or 0.2 to 15° SR, depending upon the required freeness. The stock or pulp produced according to the fiber loading process further possesses a lower water retention value of 2 to 25% depending upon the raw material used in the production process. This permits a more effective production of various paper grades, for example FL (FL=fiber loaded) copy and printing paper of all types, FL coating paper of all types, FL news print of all types and FL cigarette paper of all types, FL B&P paper of all types, FL kraft sack paper of all types and FL filter paper, since the water in the stock suspension can be removed faster. The stock therefore dries accordingly faster.

[0018] By utilizing the fiber loading technology in the pulper or in the batch-container, the optical characteristics of the paper suspension and the raw material can be improved by 0.5 to 30 lightness points, preferably by 1 to 25 lightness points—predominantly through masking of the contaminants such as ink particles and dirt. In addition, a conversion of non-activated fiber stock components, for example non-converted calcium hydroxide, PCC (precipitated calcium carbonate), GCC (ground calcium carbonate), lime components, etc. which are embedded in the recycled paper raw material or in the DIP-pulp occurs.

[0020] It is advantageous if the aqueous fiber raw material is diluted to a fibrous stock suspension having a consistency of between 0.1 and 20%, especially diluted to a consistency of between 2 and 18%.

[0022] It is advantageous if the calcium hydroxide or the calcium oxide is mixed into the aqueous fiber stock in a range of between 0.1 and 60% of the existing solids content of the volume of the dry fiber stock.

[0028] In this connection it is advantageous if the pressure vessel is opened by a valve or a sluice before the fiber loading reaction, or after the reaction.

Problems solved by technology

The print particles including flexo-ink cannot be removed through a floatation process, or can be removed only with great difficulty.

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