The present invention pertains to the field of pulp or paper making. More specifically the present invention relates to a method of preventing a build-up of slime or removing slime from a surface contacted with water from a pulp or paper making process. The present invention can control slime in an efficient and environmentally friendly way.

The invention relates to a method for pitch control and/or removal during bleaching of cellulosic fibres. Cellulosic fibres are obtained from a pulping process and formed into an aqueous cellulosic fibre suspension, and bleaching of the cellulosic fibre suspension is performed in a bleaching process comprising at least one acidic stage, where pH of the cellulosic fibre suspension is <6. A pitch control agent is added to the cellulosic fibre suspension before the acidic stage, wherein the pitch control agent comprises at least one cationic polymer comprising cationic functional groups which are hydrolysed at pH 9.0

The invention relates to a method for pitch control and/or removal during bleaching of cellulosic fibres. Cellulosic fibres are obtained from a pulping process and formed into an aqueous cellulosic fibre suspension, and bleaching of the cellulosic fibre suspension is performed in a bleaching process comprising at least one acidic stage, where pH of the cellulosic fibre suspension is <6. A pitch control agent is added to the cellulosic fibre suspension before the acidic stage, wherein the pitch control agent comprises at least one cationic polymer comprising cationic functional groups which are hydrolysed at pH 9.0

A method for monitoring hydrophobic particles contained in a pulp suspension, includes obtaining a sample from a pulp suspension or a filtrate of the pulp suspension. A fluorescent dye is added to the sample to stain particles in the sample. The sample is fractionated to obtain at least a first fraction and a second fraction, wherein the second fraction is a fiber fraction. The method includes for the obtained fractions, fluorescence emitted by the particles in the fractions, calculating an integral of the fluorescence measured for the fractions excluding the fiber fraction, and correlating the calculated integral of the fluorescence to the amount of acetone soluble material in the pulp suspension, and optionally measuring light scattering signal of the particles in at least first and second fractions.

A method of reducing contaminants in a pulp or papermaking process includes the steps of: providing a lignocellulosic pulp comprising lignocellulosic fibers and at least one hydrophobic contaminant; providing a cationic polymer; providing a cleaning blend comprising a vegetable oil alkyl ester and at least one surfactant; and applying the cationic polymer and the cleaning blend to the lignocellulosic pulp to reduce a content of the at least one hydrophobic contaminant in the pulp or papermaking process.

A method of reducing contaminants in a pulp or papermaking process includes the steps of: providing a lignocellulosic pulp comprising lignocellulosic fibers and at least one hydrophobic contaminant; providing a cationic polymer; providing a cleaning blend comprising a vegetable oil alkyl ester and at least one surfactant; and applying the cationic polymer and the cleaning blend to the lignocellulosic pulp to reduce a content of the at least one hydrophobic contaminant in the pulp or papermaking process.

A method includes forming an aqueous fibre suspension including cellulosic fibres from one or more raw material flows, and applying at least one chemical and/or physical control measure to the aqueous fibre suspension or at least one of its raw material flows for control of microbial activity in the aqueous fibre suspension or the raw material flow before an inlet of an intermediate residence entity. In this manner a starting ORP value for the aqueous fibre suspension is obtained. The aqueous fibre suspension is in the intermediate residence entity at least a minimum delay time. A final ORP value is measured for the aqueous fibre suspension after an outlet of the intermediate residence entity before the formation of the fibrous web. An ORP difference value between the starting ORP and final ORP values is calculated. Finally, the aqueous fibre suspension is formed into a fibrous web and dried.

A method for suppressing sedimentation of suspended substances ef the present invention is a method for suppressing sedimentation of suspended substances in water at the bottom of a tank disposed in a water system in papermaking equipment, comprising a step of blowing an oxygen-containing gas into the water, for stirring and aeration; a step of detecting a change with time in existence states of the suspended substances in the tank by the stirring and the aeration; and a control step of feeding at least one of an oxygen-containing gas and a slime control agent to the tank based on the detection result to suppress the sedimentation of the suspended substances in the tank.

A method of controlling volatile fatty acid (VFA) content in a pulp, paper, and/or board making processes is disclosed. The method may be used to provide process improvements in the form of reduced microbial contamination and odor, reduced starch degradation, optimized retention, and improved runability. The method includes treating a process flow comprising a cellulosic material comprising a starch with a VFA control agent. The VFA control agent is non-biocidal, comprises a surfactant or dispersant, a chelator or sequestrant, or a combination thereof, is capable of inhibiting amylase activity in the process flow, and is utilized in an amount sufficient to inhibit microbiological production of one or more VFA. The method optionally includes treating the process flow with a biocidal agent in combination with the VFA control agent.

A method for the production of paper products, such as paper and cardboard, by recycling cellulose-based raw materials containing starch. The method includes the steps of pulping in water cellulose-based raw materials containing starch, particularly recycled paper products, obtaining a pulped mass; adding to the pulped mass of the previous step under agitation a mineral acid in a quantity that is suitable to obtain a pH of the pulped mass not lower than 4, and obtaining a pulped mass treated with acid. The method further includes the step of subjecting the pulped mass treated with acid obtained in the second step, optionally treated with other chemical additives, in succession, to filtration, pressing and drying, and obtaining a paper product. Paper products obtainable by this method are also related.